Plasma cutting

Mar 31, 2010 at 07:18 o\clock

Plasma cutting is an important tool in metal industry

by: sanben   Keywords: Plasma, cutting, machines

The present invention is related to a protective case for stowage of a cnc plasma cutter wherein the plasma cutter can be placed into the protective case in the same orientation as it used. The plasma cutter is securely retained within the protective case by formations on the bottom of the case and on the lid that sandwich and hold the plasma cutter therebetween to prevent its movement within the case. The protective case also has provisions for stowing an accessory box and a plug accessory and which are also securely retained to prevent movement within the protective case.

Plasma cutting is an important tool in any metal fabrication industry. Plasma cutters, or plasma torches, are a way to make clean cuts through metal, often a difficult material to work with. Plasma cutters use high temperatures to achieve these cuts with high accuracy. But plasma-cutting technology isn't as fantastic as it seems. Plasma cutters were first used during World War II. Since then, they've had improvements and upgrades but remain a very effective tool.

A protective case for stowing a plasma cutter having cables extending therefrom, the protective case comprising a base having ends, lateral sides and a bottom forming a chamber, a lid affixed to the base having an open and closed position, the lid having an inner lid surface, the base having an inner bottom surface having a formation configured to receive and securely retain a plasma cutter, the chamber providing a space for stowing cables, the inner lid surface having a formation configured to contact a plasma cutter when positioned within the protective case, wherein a plasma cutter is sandwichable between the formation formed on the inner lid surface and the formation of the inner bottom surface to hold the plasma cutter from movement within the protective case.

The roots of plasma cutting machine first appeared in the American factories that were converted into military aircraft production plants during World War II. This type of welding utilized gas with electrical currents, resulting in welds that were protected from oxidation. In the 1960s, this technique changed so that the gas pressure and flow were increased. The welding temperature became hot enough to melt through metal. This led to the plasma torch, which is how plasma cuts are performed.

The present invention relates generally to plasma cutting systems, and, more particularly, to a protective case for containing a plasma cutter.

Plasma cutting is a process in which an electric arc is used for cutting or gouging a workpiece. The plasma cutter is generally contained within a housing and provides output power to a pair of cables that extend from the plasma cutter apparatus. One of the cables has a torch that is located at the outer end of the cable and the other cable has a work clamp at its outer end that is adapted to be attached to the workpiece.

A cnc plasma cutting machine   works by forcing gas through a narrow opening and then putting an electric current through it. The gas can be oxygen, nitrogen or air, but the temperatures superheat the fuel into plasma, which is a completely different state of matter. While the plasma gas cuts into metal, another gas acts as a shielding gas to protect the cut.
Other cutting tools besides plasma cutters include high-definition plasma and lasers. Plasma is regarded as cheaper than the other two and can cut nonferrous, or noniron, metals as well as steel. In terms of speed, plasma is the fastest, and lasers are the slowest. However, laser cutting is regarded as the most accurate, able to achieve high-precision cuts. Plasma-cutting produces a bevel, which is noticeable in smaller holes, but less noticeable in thinner materials.

The plasma cutter apparatus is designed to be a portable unit, that is, the plasma cutter can be carried by a person from location to location. Basically, the new inverter based plasma cutters now achieve the portability of other industrial power tools. With such portability, however, there is an increased risk of damage to the plasma cutter manufacturer which increases the importance of protection in transport and storage.

Plasma cutting can be used by many kinds of workers in a variety of conditions. In the auto industry, plasma cutters are used to cut out parts and shapes. In heavier industries, it is used to slice through large sheets of metal. As a handheld tool, it can be useful in auto shops or by locksmiths when a bore needs to be made. Computer numerically controlled (CNC) machines allow workers to arrange shapes using a computer screen, which the plasma cutting device will then follow and automatically cut.

While there are protective cases used among highly portable power tools, such as drills, saws and the like, at the present, protective cases are not widely used with plasma cutters. Protective cases have also been used on portable welding equipment, however, these protective cases for that purpose require manipulation of the power source from a natural vertical position to a horizontal position. In addition, the weld and ground cables for such welding equipment must be detached from the power source and be deliberately arranged in a specific manner into a storage position.

With a plasma cutter supplier , the reorientation of the cutter is made more difficult by the comparative size, weight and amount of cabling that needs to be manipulated, as compared with standard power tools.

Accordingly, it would be advantageous to have a protective case that requires little, if any, cable and power source manipulation in order stow the plasma cutter therein. In addition, it would be advantageous to have a protective case that requires minimal power source and cable manipulation for stowage in the protective case, while closely matching the aspect ratio of the plasma cutter to maximize space efficiency. Because plasma cutting machines have become smaller and more affordable, artists can more easily use metal as a medium for art. Two tools that also make this possible are handheld tools and CNC machines. They allow artists to make fine, detailed cuts and lines similar to a paintbrush.

 

 

source:townhall|plasma cutting machines

Mar 31, 2010 at 05:35 o\clock

Spiral Tubeformer for the pipe industry

by: sanben   Keywords: Spiral, Tubeformer

A continuous tube T is Spiral Tubeformer by spirally-winding an extruded thermoplastic ribbon R having mating edges which are joined together to form a spiral seam and having at least one reinforcing rib 3 which, when in its spiral wrapped form, projects radially out from the tube. At predetermined lengths, the tube is cut and at the same time the outer surfaces of the tube on each side of the cut are shaped to facilitate handling and interconnecting of pipe section 1 thus formed. At least one end of the pipe has an annular groove 6 at a uniform distance from that end. This groove is formed by cutting a path through each of the radially extending reinforcing ribs intersecting its annular path. An elastomeric O-ring 8 engages the outer surface of the pipe and the axial movement of the O-ring is restrained by the walls of the groove formed by the radially extending reinforcing ribs. An apparatus 30 for cutting the tube at predetermined lengths into pipe sections while the tube is proceeding out of the spirally-winding operation also imparts to the outer surfaces the desired shape as well as cuts the groove for the elastomeric O-ring. This apparatus performs this cutting and shaping operation without interrupting the continuous forming of the tube from the spirally-wound thermoplastic ribbon.

"Seamless" steel pipes are those whose manufacture does not involve welding of any kind. The process starts with a long, solid cylinder of steel known as a "billet." The billet is loaded into a special machine that uses electrical resistance to heat the billet to a malleable temperature. A pair of rollers with perpendicular axes (Figure 1) rotate the heated billet rapidly around its own axis while slowly drawing it into special instrument known as a "piercer." The piercer slowly enters the rotating billet as a near perfect Tube forming around it. To better illustrate, think of the process like a potter's wheel; when you put your finger into the top of the spinning clay, a perfectly-symmetrical hole forms around the digit. Formally, this phenomenon is known as the "Mannesmann Effect."

To get the desired wall thickness, the hollow billet enters an "elongator," which is a new set of perpendicular rollers with a specifically-shaped piercer to squeeze it into a longer, thinner tube.
The present invention relates to apparatus for simultaneously shaping the ends of lengths of pipe and severing these lengths from continuous tube being generated by a tube making machine. This tube making machine forms tube of selected diameters in virtually unlimited length by wrapping a ribbon of thermoplastic extrusion around a mandrel or series of mandrels. This extruded ribbon of thermoplastic material includes first and second edges which are abutted one against the other in a spiral in order to form a substantially imperforate pipe. These first and second edges have mating shapes to provide an interlocking function. The ribbon further includes at least one upstanding, radially extending rib which results in the Spiral Tubeformer having greater rigidity or resistance to crushing forces than would a pipe of uniform wall thickness based on equivalent material/unit length.

The hot extruded method is a variation on seamless pipe. Taking the first-stage hollowed billet, manufacturers load it into heating press known as an "extruder" (Figure 2). A long metal bar meant to set the finished pipe diameter (i.e. the "mandrel") runs from the base of the press up through the middle of the billet. The other end of the press is covered with a patterned opening known as a "die," designed to set the outer diameter of the finished pipe. Electrical resistance heats the billet and the powerful hydraulic press pushes the malleable billet up through the die, resulting in a long stretch of steel pipe.

Due to the peculiar surface profile provided to the thus fabricated pipe, and due to the fact that the pipe progresses from the pipe forming machine along its longitudinal axis while simultaneously rotating about that axis, unusual problems arise concerning forming pipe sections of predetermined lengths. In order to meet reasonable production rates, the continuous tube must be cut into pipe section without interrupting the production of the tube itself. Once severed, these pipe sections require further alteration before they can be practically used in the field. The radially extending Spiral Tube former progressing along the outside of the pipe, while having great advantage in imparting strength, complicate the interfitting of the pipe section to form a useful fluid conduit.

A long, rectangular of steel is fed into a set of parallel rollers (Figure 3). These rollers help smooth imperfections and squeeze the material into the desired final thickness. These flattened sheets then enter a blast furnace, which heats them for greater malleability. Once heated, the sheets feed into a series of parallel rollers, which gradually bend the sheets into a tight spiral. This process is formally known as "forming."

Just as the edges of the sheets touch, an automatic arc welding torch fires along the seam, melting the metal and causing them to fuse together. The "butt" qualifier is short for "butt joint"--a welding joint consisting two non-overlapping pieces with non-beveled edges.
There have been many examples in the prior art of attempts to utilize the benefits of forming imperforate conduit from a spirally-wound extruded strip of thermoplastic material.

U.S. Pat. No. 3,914,147 discloses a machine for continuously forming a spirally- formed tube from an extruded ribbon of thermoplastic material. FIG. 6 of this patent shows a device for severing the thus produced tube as it progresses from the disclosed tube forming machine . This severing system includes a scanning device which apparently senses the rate of movement of tube along its longitudinal axis. This scanning device supplies an electrical signal to a servo motor which controls the traveling speed of a sawing mechanism in order to permit the sawing mechanism to cut through the cylindrical wall of the tube.

Designed for especially thin thicknesses of steel, ERW pipes start the same as butt welded pipes, except that extreme heating before the Spiral Tubeformer usually is not necessary. Once the edges of the coiled sheet touch, the seam passes between a pair of special electrodes set just millimeters apart. The terminal of each electrode touch the pipe on either side of the seam and pass a powerful current between the touching edges. The strength of the voltage generates massive electrical resistance across the steel. However, because the metal is so thin, it cannot displace the heat quickly enough and soon reaches its melting point, causing the two sides to fuse together.

Mar 24, 2010 at 08:30 o\clock

This invention of an air plasma arc cutter

by: sanben   Keywords: CNC, plasma, cutting, machine

An air Plasma Cutting Machine includes spaced apart front and rear panels. A partition wall has its opposed two edges coupled to the front and rear panels to divide the space therebetween into upper and lower regions. An AC-to-DC voltage converter is disposed in the upper region and converts an AC voltage to a DC voltage to be applied between a torch electrode of a torch of the cutter and a workpiece. An air compressor supplies compressed air around the torch electrode and is disposed in the lower region. The air compressor has a threaded bolt which extends through the partition wall from the lower into upper regions. A nut is screwed onto the bolt in the upper region to thereby secure the air compressor to the partition wall. Shock absorbing members are disposed between the nut and the partition wall and between the air compressor and the partition wall.

There are three states of matter encountered in everyday life, and a fourth that is not as common. These exist as water, solid and gas--with the last being plasma. Almost 99 percent of all matter in the universe is plasma, however it is not as common on earth because it exists at extremely high temperatures. We are more likely to see it in the sun or in the form or l ightning. CNC Plasma cutter is also used in neon and florescent lights.

This invention relates to an air plasma arc cutter which cuts a workpiece by a air plasma generated by a high DC voltage, and, more particularly, to such an air plasma arc cutter with compressed air supplied from an air compressor built in the cutter.
In an air plasma arc cutter, an AC voltage is converted to a high DC voltage by an AC-to-DC voltage converter circuit. The high DC voltage is applied between a torch of the cutter and a workpiece which is an object to be cut by the cutter. The application of the DC voltage causes an arc to be generated between the torch and the workpiece. An air compressor supplies compressed air around the torch and into a gap between the torch and the workpiece. The arc ionizes the compressed air into plasma, and the workpiece is cut by the plasma.

Japanese Examined Patent Publication (KOKOKU) No. HEI 6-38985 discloses an air plasma arc cutter including an air compressor and an AC-to-DC voltage converter housed in a single casing. This can reduce the size of the cutter.
To understand where plasma cutters china in, first look at the states of matter in the world and its properties. The atom is made up of neutrons and protons in the nucleus surrounded by a cloud of electrons. When super heated, these electrons move very quickly in random patterns and are released from their bond to the nucleus. When the electrons leave their bond to the atom, they are negatively charged and leave behind positively charged nuclei known as an ions. The hotter the electrons get, the faster they move and when they collide they release vast amounts of energy.

An air plasma arc cutter according to the present invention includes front and rear panels spaced from each other. Opposed ends of a partition wall are coupled to the front and rear panels. The partition wall partitions the space defined between the front and rear panels into first and second regions. AC-to-DC voltage converting means is disposed in the first region. The voltage converting means converts an AC voltage to a DC voltage which is applied between a torch electrode of a torch of the CNC plasma cutting machine and a workpiece to be cut. Air compressor means is disposed in the second region. The air compressor means supplies compressed air around the torch electrode of the torch.

A plasma cutter uses this energy to its advantage. It has a nozzle with two passages for gas and a center negative electrode. When it is charged with electricity and held close to the metal to be cut, it creates a very hot spark. A gas such as argon flows from the closest passage surrounding the arc which is extremely hot and causes the molecules to move a an extremely accelerated rate, colliding into each other and releasing a great amount of energy. To contain the unpredictable arc within a small confine a second passage flows a shielding gas. The plasma builds to an incredible 30,000 degrees--capable of plasma cutter manufacturer . It can cut through thick sheets of metal like butter.

The air compressor means may be provided with a bolt which extends from the second region through the partition wall into the first region. A nut is screwed onto the bolt in the first region to secure the air compressor means to the partition wall. The partition wall desirably has such strength as to bear the weight of the air compressor means. A first shock absorbing member is disposed between the nut and the partition wall, and a second shock absorbing member is disposed between the air compressor means and the partition wall.

The first and second shock absorbing members may be disposed around the bolt. The first and second shock absorbing members may be ring-shaped so that the bolt can extend through the absorbing members.
Using water as an example, the first state of matter is a solid. A solid has a definite shape and is made up of neutrally charged atoms arranged in a hexagonal pattern. Ice is a good example. Liquid is the next state of matter. In this state the molecules are still bonded together but move relative to each other very slowly. Gas is the next state in which the molecules move around at a high speed independently from one another and separate, leaving the negatively charged electrons and positively charged nuclei known as ions. Plasma is formed as the last state of matter where the electrons and ions are moving so fast that when they collide with each other they produce huge amounts of energy.

 

 

source:townhall|plasma cutter

Mar 16, 2010 at 08:36 o\clock

A machine for making generally L-shaped flanges

by: sanben   Keywords: flange, forming, machine

A machine for making generally L-shaped flanges for joining sections of flat oval ductwork, said machine comprising: an input section for receiving a strip of sheet metal stock material; a cutter for cutting the sheet metal stock material into lengths corresponding to individual flanging machine ; a set of angle-forming rolls for forming each length of sheet metal stock material into an angled length of material having a generally L-shaped profile; and a set of shaping rolls for forming the angled lengths of material into flat oval flanges generally L-shaped in profile and requiring only a single joint.

Lockformer machines use a series of rolls to roll the edge of a piece of sheet metal gradually to form various types of connectors commonly used in the HVAC industry. Roll-forming machines like Lockformer are intimidating until you learn how to operate the machine properly. Learning to use a Lockformer machine requires using the piece of equipment. Making a sheet metal box will allow you to become familiar with the Lockformer Pittsburgh Lock Model 20 with the auto-guide flange attachment. Learning to use one type of Lockformer machine is all you need because all Lockformer roll-forming machines operate the same way.

In an exemplary embodiment of the invention, a connector, which may also be termed a flange assembly, for joining sections of flat oval ductwork takes the form of a pair of flat oval flanges that are generally L-shaped in profile. Each of the flange machine is made of a single piece of metal requiring only a single joint.
A corresponding method embodying the invention for joining sections of flat oval ductwork includes the steps of providing a pair of flat oval flanges generally L-shaped in profile. Each of the flanges is made of a single piece of metal requiring only a single joint. The L-shaped profile is defined by a duct-attachment leg generally parallel to the longitudinal axis of the ductwork sections to be joined, and by a flange-attachment leg extending generally radially outwardly generally perpendicularly to the longitudinal axis of the ductwork sections to be joined. The flat oval flanges are inserted into the respective ends of the ductwork sections to be joined, and the duct-attachment legs are attached to the respective ductwork sections. The flange-attachment legs of the flat oval flanges are abutted against each other, preferably with an intermediate gasket, and are then fastened to each other, preferably employing clips.

A corresponding machine embodying the invention for making generally flange forming machine for joining sections of flat oval ductwork includes an input section for receiving a strip of sheet metal stock material, and a cutter for cutting the sheet metal stock material into lengths corresponding to individual flanges being made. The machine additionally includes a set of angle-forming rolls for forming each length of sheet metal stock material into an angled length material having a generally L-shaped profile, as well as a set of shaping rolls for forming the angle lengths of material into flat oval flanges, generally L-shaped in profile and requiring only a single joint.

Set the scribe to 1/2 an inch. Mark each side of the two 12 1/2-inch pieces of sheet metal with the scribe. Cut the corners where the lines cross with a pair of aviation snips. Scribe a 1/2-inch line on one of the 14 1/4-inch sides of the 14 1/4-by-49 3/8th inch piece of sheet metal. Set the scribe to 1 1/8th inch. Mark the remaining three sides of the 49 3/8-inch long sheet metal.

Remove all the corners where the scribe lines cross. Cut the corners with the aviation snips, 1/8th of an inch on the outside of the scribe line to the point of intersection of the scribe marks. Measure over from the edge of the sheet metal on the side with the 1/2 inch notch with the tape measure. Mark the metal at 12 1/2 inches, 24 1/2 inches, and 36 1/2 inches. Rotate the sheet metal and mark the other side with the same dimensions. Notch each mark from the edge of the sheet metal down to the 1 1/8th inch scribe line.

Align the 1/2-inch scribe side of the 49 3/8-inch piece of sheet metal with the guide on auto-flange attachment and slowly push the metal into the flange former manufacturer . Repeat the process with the eight edges of the two 12 1/2-inch square pieces of sheet metal.
Bend the 49 3/8-inch long piece of sheet metal at the 12 1/2-, 24 1/2- and 36 1/2-inch marks in a sheet metal hand brake. Insert the 1/4-inch flange into the Pittsburgh seam and seat the flange with the 3/8-inch flat bar. Peen over the top of the Pittsburgh seam to lock the sheet metal together.

 

 

source:townhall|flange machine

Mar 16, 2010 at 08:26 o\clock

Plasma arc systems are widely used for cutting metallic materials

by: sanben   Keywords: plasma, cutter

 Plasma arc systems are widely used for cutting metallic materials and can be automated for automatically cutting a metallic workpiece. In general, a CNC plasma cutter arc system includes a plasma arc torch, an associated power supply, a remote high-frequency (RHF) console, a gas supply, a positioning apparatus, a cutting table, a torch height control, and an associated computerized numeric controller. FIG. 1 shows an example of a plasma arc system.

In operation, a user places a workpiece on the cutting table and mounts the plasma arc torch on the positioning apparatus to provide relative motion between the tip of the torch and the workpiece to direct the plasma arc along a processing path. The user provides a start command to the computerized numeric controller ( CNC) to initiate the cutting process. The CNC accurately directs motion of the torch and/or the cutting table to enable the workpiece to be cut to a desired pattern. The CNC is in communication with the positioning apparatus. The positioning apparatus uses signals from the CNC to direct the torch along a desired cutting path. Position information is returned from the positioning apparatus to the CNC to allow the CNC to operate interactively with the positioning apparatus to obtain an accurate cut path.

The power supply provides the electrical current necessary to generate the CNC plasma arc. The power supply has one or more dc power modules to produce a constant current for the torch. Typically, the current can be set to discreet values. The power supply has a microprocessor, which regulates essentially all plasma system functions, including start sequence, CNC interface functions, gas and cut parameters, and shut off sequences. For example, the microprocessor can ramp-up or ramp-down the electrical current. The main on and off switch of the power supply can be controlled locally or remotely by the CNC. The power supply also houses a cooling system for cooling the torch.

The gas console controls flow of plasma and shield gases to the torch. The gas console houses solenoid valves, flow meters, pressure gauges, and switches used for plasma and shield gas flow control. The flow meters are used to set the preflow rates and cut flow rates for the plasma and shield gases. The gas console also has a multi-inlet gas supply area where the required plasma and shield gases can be connected. A toggle switch can be used to select the plasma gases. The plasma and shield gases are monitored by gas pressure gages. In order to operate the gas console, all settings must be manually selected.

Plasma cutting machine   use an inert gas and electrical current to create a powerful torch that can cut through metal. The gas is blown through the machine's nozzle at high speed along with an electrical arc. The arc heats up the gas and converts it into hot plasma. The heat of the torch melts the metal as it cuts, leaving smooth, clean edges.
Portable plasma cutters are used by contractors to cut metal while working out in the field. This makes it easy for mechanical contractors or HVAC servicemen to make needed repairs on-site instead of having to bring large pieces of metal back to the shop for cutting. Many times, all that is needed is a simple trim to make two metal pieces fit together. Having the plasma cutter manufacturer right there on the site keeps the job from slowing down while waiting for the fabrication shop to make the necessary adjustments.

The plasma arc torch generally includes a torch body, an electrode mounted within the body, passages for cooling fluid and cut and shield gases, a swirl ring to control the fluid flow patterns, a nozzle with a central exit orifice, and electrical connections. A shield can also be provided around the nozzle to protect the nozzle and to provide a shield gas flow to the area proximate the plasma arc. Gases applied to the torch can be non-reactive (e.g. argon or nitrogen) or reactive (e.g. oxygen or air).

In operation, the tip of the torch is positioned proximate the workpiece by the positioning apparatus. A pilot arc is first generated between the electrode (cathode) and the nozzle (anode) by using, for example, a high frequency, high voltage signal from the RHF console. The pilot arc ionizes gas from the gas console passing through the nozzle exit orifice. As the ionized gas reduces the electrical resistance between the electrode and the workpiece, the arc transfers from the nozzle to the workpiece. The torch is operated in this transferred plasma arc mode, which is characterized by the conductive flow of ionized gas from the electrode to the workpiece, to cut the workpiece.

TheCNC plasma cutting machine arc system as described above has high cycle time. First, a torch operator must know some basic cutting parameters, such as the material to be cut, the thickness of the workpiece, and the plasma gas to be used. Then, the operator must review a series of tables found in books to manually set many parameters such as the power settings on the power supply or the gas flow on the gas console. Having to look up additional parameters takes time and may result in operator error as manual input can be inaccurate.

In addition, some components such as the torch height control and the power supply have their own control, which can be redundant. Furthermore, there is no feedback mechanism between the components of the plasma arc system to optimize the operation of the plasma arc system.
Artists also use small plasma cutters to create unique works from metal. The tip of the plasma cutter can make very fine incisions in the metal, allowing the artist to make intricate patterns in the metal. Metal templates can also be created with a plasma cutter and used as a stencil for other forms of art.

Plasma cutters are also finding their way into the demolition business because of their ability to cut away large sheets of metal. The power of the plasma cutter's beam allows demolition crews to remove structures and pipes far more quickly than if the metal had to be cut by hand. Disposal of the material is also more convenient when there is a plasma cutter on site. The sheets of metal can be sliced into smaller pieces that are easier to handle and to load into trucks for removal from the site.

 

 

source:townhall|plasma cutting machine

Mar 9, 2010 at 07:07 o\clock

Uses of Plasma cutting table machine

by: sanben   Keywords: Plasma, cutting, table, machine

A process and apparatus for cutting a material using a plasma are jet provides improved uniformity along the length of cut, despite variations in cutting speed. This is achieved by pulsing the arc current and dynamically varying the pulsing. By this means the momentum of the plasma arc jet can be maintained substantially constant whilst the amount of energy delivered by the plasma arc jet is controllably varied. The pulsing can be dynamically varied in dependence on one or more of the cutting speed, the angle of ejection of a stream of molten material from the cut, the size of the droplets of the ejected material, the intensity of spectral pattern of light emitted from the cnc plasma cutter   jet and material interface, and the arc voltage. The pulses can be varied by varying one or more of the pulsing frequency, the pulse duty, upper value of the pulse current, and depth of the pulses.

Plasma cutters use an inert gas and electrical current to create a powerful torch that can cut through metal. The gas is blown through the machine's nozzle at high speed along with an electrical arc. The arc heats up the gas and converts it into hot plasma. The heat of the torch melts the metal as it cuts, leaving smooth, clean edges.

In plasma arc cutting technology, the quality of a cut can be described in terms of the dimensional accuracy of the cut parts, cut angle (degree of squareness of the cut face in the direction normal to the cut), the amount of dross on the bottom of the workpiece (which will usually be metal plate), amount of spatter on the top of the workpiece and sharpness of the top and bottom edges of the cut part. Cut quality is determined, in particular, by the effectiveness of metal melting and removal from the workpiece, which depends on factors including the thermal energy delivered to the workpiece and on the momentum of the plasma jet.

The thermal energy delivered to the workpiece depends on the electrical energy of the plasma arc and on the efficiency of energy transfer to the workpiece. If it is assumed that the energy transfer efficiency is substantially constant, then the electrical energy of the plasma arc can be taken as a measure of the thermal energy delivered to the workpiece, which is the approach adopted in the following description.

The amount of electrical energy per unit length of cut is a significant process variable affecting the material melting process. This process variable is determined by the cutting speed, arc voltage, arc current and pressure of the plasma forming gas. Conventional process control for Plasma Cutting Machine relies on regulation of the cutting speed, arc voltage, arc current and plasma gas pressure around constant (optimal) set points which are chosen to ensure the best cut quality for a given plate. In general, the optimal cutting speed cannot be maintained at all times, for example, for a plasma arc cutting operation that is integrated with a manufacturing process such as welding, as in continuous pipe making, the optimal welding speed may determine the use of a non-optimal cutting speed. Also the optimal cutting speed cannot be maintained during the cutting of complex parts using profiling machines because of the finite acceleration capabilities of these machines. That is, the deceleration along the x-axis and acceleration along the y-axis of such a machine during the traversal of a 90° corner results in a decrease of the cutting speed near the corner.

Portable plasma cutter are used by contractors to cut metal while working out in the field. This makes it easy for mechanical contractors or HVAC servicemen to make needed repairs on-site instead of having to bring large pieces of metal back to the shop for cutting. Many times, all that is needed is a simple trim to make two metal pieces fit together. Having the plasma cutter manufacturer right there on the site keeps the job from slowing down while waiting for the fabrication shop to make the necessary adjustments.

Artists also use small plasma cutters to create unique works from metal. The tip of the plasma cutter can make very fine incisions in the metal, allowing the artist to make intricate patterns in the metal. Metal templates can also be created with a plasma cutter and used as a stencil for other forms of art.

The effect of variations in the cutting speed on the amount of energy per unit length of a cut is twofold. First, the amount of energy per unit length of cut increase with decreasing cutting speed for constant arc voltage, arc current and pressure in the nozzle chamber. Second, the arc voltage increases with decreasing cutting speed thus further contributing to the increase in the amount of energy per unit length of cut. Such an increase in the arc voltage is due to an effective increase in the length of the arc caused by the movement of the arc anode root down the cutting front at reduced cutting speed.

Plasma cutters are also finding their way into the demolition business because of their ability to cut away large sheets of metal. The power of the plasma cutter's beam allows demolition crews to remove structures and pipes far more quickly than if the metal had to be cut by hand. Disposal of the material is also more convenient when there is a ductwork plasma cutter on site. The sheets of metal can be sliced into smaller pieces that are easier to handle and to load into trucks for removal from the site.

The increase in the amount of energy per unit length of cut when the cutting speed reduces results in an excessive amount of molten metal which cannot be completely removed by the momentum of the plasma jet. Further, at low cutting speeds the shape of the cut front changes resulting in a change in the direction of ejection of molten metal. This leads to dross formation and possibly to corner undercut. Dross is often formed well beyond the deceleration-acceleration region of a corner which is due to the shape of the cut front. Since the cut front depends upon the diffusion of heat through the plate, there is a time dependent mechanism associated with dross formation initiated in the vicinity of the profile corner. This means that a significant part of the profile may be affected by dross formed at the bottom of the plate.

The precision of a plasma cutter is also beneficial to plumbing contractors. When pipes are cut with a standard torch, the ends can become distorted or flattened. This makes it difficult to fit the ends of two pipe sections together. The tip of a plasma cutting table manufacturer also leaves a much smoother edge than using a blade. This reduces the amount of time that must be spent grinding down the edges of the newly cut pipes.

In the prior art the amount of energy per unit length of cut has been controlled by varying the torch-to-workpiece distance. However the amount of variation in this distance that is available and its effect on the amount of energy is generally insufficient to eliminate dross formation in the vicinity of profile corners. The amount of energy per unit length of cut may also be controlled by varying the arc current in response to changes in the cutting speed, for example, by decreasing the arc current while decreasing cutting speed. This type of control of the amount of energy per unit length of cut may ensure effective metal melting, however the cut quality also depends on the effectiveness of metal removal from the workpiece, which in turn depends on the momentum of the plasma jet.

Plasma cutters
are used in manufacturing to repeatedly make the same precise cuts. The cutter is attached to a piece of computer numerically controlled (CNC) equipment, which directs the torch to make its specified cut. This has drastically reduced manufacturing costs in the HVAC industry, which relies on CNC plasma cutters to mass produce metal ductwork.

It can be shown that the momentum of a plasma arc jet emanating from the nozzle of a plasma arc cutting torch is approximately proportional to the gas pressure in the nozzle chamber and that there is a strong relationship between this pressure and arc current. Thus the pressure in the nozzle chamber, and therefore the plasma jet momentum, varies with current. The effect of this is that although the energy per unit length of cut could be controlled effectively by varying the arc current, this is at the expense of the plasma jet momentum. That is, a decrease in arc current results in a decrease in the momentum of the plasma jet and this reduces the effectiveness of metal removal by the plasma jet. Thus effective metal removal and therefore a high quality of cut around a profile cannot be maintained.

Japanese Patent No. 1884596 (Kokai 61-262464) by S Hagihara et al, discloses pulsing of the arc current to reduce the amount of dross and to enable high speed cutting. Soviet patent document SU-1632670-A, also discloses pulsing of the arc current to increase the cutting speed. However in both of these disclosures the arc pulsing parameters are fixed during cutting. Japanese Kokoku 44-29967 also discloses pulsing of the arc current, but with a cyclic variation in the amplitude of the pulses to uniformly distribute the heat of the Plasma Cutting Machines down the depth of the cutting groove to reduce narrowing and irregularities in this groove.

Although the above disclosures for pulsing the arc current give improved cut quality, the uniformity over the length of a cut, particularly when producing parts having a complex profile, is variable. Also in the above Japanese and Soviet patent documents, the current pulsing is "upwards" in the sense that the torch is operated at or near its DC rating and current pulses of increasing amplitude are imposed on this DC current such that generally the current rating of the nozzle is momentarily (i.e. for the duration of each pulse or over a lesser period) and repeatedly exceeded. This can lead to problems such as double arcing and thus a shortened lifetime for the torch consumables.

 

 

from:townhall|plasma cutting machine

Mar 9, 2010 at 06:53 o\clock

How does a Rotary Machine work?

by: sanben   Keywords: Rotary, Machine

An improved machine for forming one or more helical grooves in the walls of glass tubes in which the glass tubes are automatically transferred from one processing area of the machine to the adjacent processing area. Lifters for engaging the open ends of the glass tubes are attached to a movable carriage assembly which provides for the transfer of the tubes from one area of the machine to an adjacent area during its forward travel and provides for the grooving of the tubes during its reverse travel. A positioning mechanism insures that the lifters are properly aligned over the open ends of the tubes prior to engagement. An arrangement is also disclosed for transferring two tubes in tandem to increase the machine's processing speed.

A Rotary Machine is a small machine (a little bit smaller than an average pack of cigarettes) with two wheels and a hand crank that is designed to roll cigarettes using tobacco, though in some instances cannabis is substituted. These machines are easy to use and purchase, though they may require some practice to get the sort of cigarette a person wants. For people who prefer to smoke unfiltered tobacco, whether because it's cheaper or they prefer to make their own blend, a rolling machine can be an extremely helpful tool that will save time and tobacco.

It is known in the art that a fluorescent lamp having an envelope of noncircular cross section produces more useful light per unit of power input than a fluorescent lamp whose envelope is of circular cross section. It is further known that a noncircular cross section in the fluorescent lamp envelope can be obtained by providing grooves, and more preferably, helical grooves along the length of the outer wall of a glass tube forming the envelope. A machine for producing helical grooves in a glass tube is described in U.S. Pat. No. 3,399,984 to D. G. Trutner et al., which is assigned to the assignee of the subject application. The machine of that patent can be functionally divided into four sections which include a loading section, a preheating section, a groove forming section and an unloading section. Transfer of a glass tube from one section of the machine to the next is accomplished by axially sliding the tube along the length of the machine. While the machine is operative for its intended purpose, it has a disadvantage in that sliding of the tubes results in marks and scratches on the outer walls of the glass tubes, which adversely affect the lamp appearance and/or efficiency.

Using Rotary Machines is a fairly simple process. The machine sits on a rectangular base with two rollers on top. One roller swings out on a hinge to reveal a long channel in the base. This channel is filled with tobacco, and it should be filled evenly to ensure a cigarette with a constant, regular burn. Once all of the tobacco has been lined in the channel (care should be taken to ensure that the tobacco is dry and loose, not clumped) the second roller is swung back and locked in place. The machine is now prepped to roll a cigarette.

The invention described herein is an improvement of the helical grooving machine described in U.S. Pat. No. 3,399,984, and includes an apparatus for automatically transferring a glass tube from one processing area of the machine to an adjacent processing area without the necessity of sliding the tube. The transferring apparatus is formed by an engaging and lifting mechanism mounted on a transfer assembly. More specifically, the transfer assembly includes pairs of lifters that are separated by a distance approximately equivalent to the length of the Spiral Tubeformer to be transferred, and are mounted on parallel shafts. The shafts are actuated simultaneously to enable the lifters to engage the open ends of the tubes and lift them from the surface of the machine.

The machine should be cranked a few times just to loosen up the tobacco in the groove. Then, a single cigarette paper should be fed into the rollers, the ungummed side going in first. The machine should be cranked carefully, and the rolling paper will be fed slowly down into the channel. As the cranks turn, the paper will be rolled around the tobacco in the groove. Once the cranking is complete, the second wheel should be swung out again. In the channel, if the user was careful and the machine worked properly, there should be a round cigarette with all of the tobacco rolled inside.

In operation of the machine of the subject invention, an actuator on the carriage assembly causes engagement of the lifters with the open ends of the glass tubes and lifting of the tubes from the surface of the machine. The carriage assembly moves longitudinally of the machine and transfers the tubes from one processing area from the machine to the adjacent processing area. The lifters are then disengaged from the open ends of the glass tubes, causing the tubes to be lowered onto the upper working surface of the machine.

The present invention also provides a novel type of rotatable lifter that performs the dual function of engaging the open ends of the Square Duct and lifting the tubes from the surface of the machine. In addition, another embodiment of the invention is disclosed wherein a first mechanism engages the open ends of the tubes, and a second mechanism lifts the engaged tubes from the working surface of the machine. The present invention also includes a positioning mechanism that insures that the carriage assembly is properly aligned over the open ends of the glass tubes in order that the lifters may properly engage the tubes.

Another embodiment of the present invention also provides a tube engagement and lifting mechanism that permits increased production of grooved glass tubes by doubling the number of tubes that can be processed in any one area of the machine.

It is therefore an object of the present invention to provide a novel apparatus for transferring a glass tube longitudinally of a helical grooving machine.

It is a further object to provide novel lifters that engage the open ends of the glass tubes and lift the tubes from the surface of the machine in one operation.

Another object is to provide apparatus for transferring glass tubes longitudinally of a grooving machine by first engaging the open ends of the glass tubes and then lifting the engagement mechanism and carrying the tubes to an adjacent processing area of the machine.

An additional object is to increase productivity of a glass tube grooving machine by simultaneous longitudinal transfer of a plurality of Spiral Tubeformer positioned in tandem relationship in one processing area of the machine.

A further object is to provide apparatus for the simultaneous longitudinal transfer of a plurality of glass tubes aligned substantially in parallel across the width of a grooving machine from one processing area of the machine to the adjacent processing area.

Another object is to provide a transfer mechanism for a glass tube processing machine that automatically positions the lifters which are attached to the carriage assembly that shifts the tubes for engagement with the glass tubes.

 

 

from:townhall|tube forming machine

Mar 2, 2010 at 07:40 o\clock

The useful of flanging machine

by: sanben   Keywords: flanging, machine

The manufacture of steel buildings rafters and columns begins with the Plasma cutting machine . The Plasma Table cuts the web, the center of the rafter or column (like the center of the letter “H”). The web moves to a holding station waiting to move by automated conveyor to the station where the web will be tack-welded to the flange

The flanging machine cuts flanges into specified lengths determined by the pre-engineered metal buildings specifications from steel bar stock. After cutting, the flanges move to a holding station waiting to move by automated conveyor to the station where the flanges will be tack-welded to the web prior to going through the automatic welding machine.

Certified welders tack-weld flanges and webs in place to form rafters and columns. The tacked rafters and columns move by conveyor to the PHI machine. At the PHI machine, an automatic welding process fuses the web and flange materials, permanently welding the flanges to the web. A Welding Inspector checks all welds to ensure that strict AISC standards are met.

We're pretty much done with major coding on Liquid (click the image for the full-sized UI), and are going to address porting tomorrow. The Windows version is essentially done, for all intents and purposes. So what is it? A through-zero flanger, that's what. If you know what a through-zero flanger is, skip the next paragraph; otherwise, read and learn.

A normal flange machine like you'd find in a guitar pedal (and most software versions) mixes a dry signal with a signal that has been delayed a tiny bit. You can recreate this with almost any delay that has very short times. The more feedback you add, the more your signal sounds like a Cylon. Pretty simple, right? A through-zero flanger is a totally different animal. With through-zero flanging, the "flanged" signal can go just as far _before_ the dry signal as it can _after_. This is the effect that Phil Spector and George Martin are talking about when they describe using two tape decks to create artificial double-tracking (ADT) effects for vocals. They're not talking about the jet-plane whoosh of Eddie's guitar on "And The Cradle Will Rock." The two effects actually have not a whole lot to do with each other.

 

 

 

 

TDC unit is one of the two universal flange making machines in the world. It can save time and material drastically with its wel-seal, strong and durable joint structure. So it is specially suitable for producing a duct with a large sectional area. Today many famous buildings in the world utilize this kind of structure in the ventilation system such as the American Kennedy Space Center, Guangzhou CITIC Plaza etc. The unit consists of a feeding frame, main tube forming machine and a shearing unit, which includes grinder and hydraulic shearing unit. The hydraulic shearing unit makes fixed cutting available with very little burr, and may be operated automatically with a maximum work speed of 6 m/min. It is divided into four types: T-20、T-30、T-35、T-40 with their corresponding duct corner T-20DC、T-30DC and T-40DC.TDC made by SBKJ may match and produce all the ducts in the DW144 standard, and has passed the HVAC PW/TMI(1987) pressure test, which is a speciality test for the intensity and sealed condition of a duct.
Main Technical Date:

 

Type
Rolls Shape
Edge wide
Capacity
Motor
Weight
Dimension
SBTDC-20A
88mm
0.8mm
3kw
2000kg
2800×600×1150mm
SBTDC-30A
120mm
1.0mm
3kw
2200kg
3000×600×1150mm
SBTDC-35A
131mm
1.0mm
3kw
3000kg
3200×600×1200mm
SBTDC-40A
141mm
1.2mm
4kw
3000kg
3200×600×1200mm
 
Type
Rolls Shape
Edge wide
Capacity
Motor
Weight
Dimension
SBTDC-20B
 
86.5mm
0.8mm
3kw
2000kg
2800×600×1150mm
SBTDC-30B
118mm
1.0mm
3kw
2200kg
3000×600×1150mm
SBTDC-40B
176mm
1.2mm
4kw
3000kg
3200×600×1200mm
 
Type
Name
Capacity
Size
Shape
T-20DC
Duct comer
2.5mm
a=95mm
 
T-30DC
Duct comer
3mm
a=105mm
 
T-40DC
Duct comer
3.5mm
a=123mm
 
LT-30
Duct comer
3mm
a=105mm
 
T-35DC
Duct comer
3mm
a=106mm
 
BC-10
Duct clip
5mm
 
 

 

 

from:sbkj|flanging machine

Mar 2, 2010 at 07:26 o\clock

Proliferation of cnc plasma cutter

by: sanben   Keywords: cnc, plasma, cutter

MIT fit gears to the various handwheel inputs and drove them with roller chains connected to motors, one for each of the machine's three axes (X, Y, and Z). The associated controller consisted of five refrigerator-sized cabinets that, together, were almost as large as the mill they were connected to. Three of the cabinets contained the motor controllers, one controller for each motor, the other two the digital reading system.

Unlike Parsons's original punch card design, the cnc plasma cutter   design used standard 7-track punch tape for input. Three of the tracks were used to control the different axes of the machine, while the other four encoded various control information. The tape was read in a cabinet that also housed six relay-based hardware registers, two for each axis. With every read operation the previously read point was copied into the "starting point" register, and the newly read one into the "ending point". The tape was read continually and the number in the register increased until a "stop" instruction, four holes in a line, was encountered.

The final cabinet held a clock that sent pulses through the registers, compared them, and generated output pulses that interpolated between the points. For instance, if the points were far apart the output would have pulses with every clock cycle, whereas closely spaced points would only generate pulses after multiple clock cycles. The pulses are sent into a summing register in the motor controllers, counting up by the number of pulses every time they were received. The summing registers were connected to a digital to analog convertor that output increasing power to the motors as the count in the registers increased.

The registers were decremented by encoders attached to the motors and the mill itself, which would reduce the count by one for every one degree of rotation. Once the second point was reached the pulses from the clock would stop, and the motors would eventually drive the mill to the encoded position. Each 1 degree rotation of the controls produced a 0.0005 inch movement of the Plasma Cutting Machine .. The programmer could control the speed of the cut by selecting points that were closer together for slow movements, or further apart for rapid ones.

The system was publicly demonstrated in September 1952, appearing in that month's Scientific American. MIT's system was an outstanding success by any technical measure, quickly making any complex cut with extremely high accuracy that could not easily be duplicated by hand. However, the system was terribly complex, including 250 vacuum tubes, 175 relays and numerous moving parts, reducing its reliability in a production setting. It was also very expensive, the total bill presented to the Air Force was $360,000.14, $2,641,727.63 in 2005 dollars. Between 1952 and 1956 the system was used to mill a number of one-off designs for various aviation firms, in order to study their potential economic impact.

The Air Force funding for the project ran out in 1953, but development was picked up by the Giddings and Lewis Machine Tool Co. In 1955 many of the MIT team left to form Concord Controls, a commercial CNC plasma company with Giddings' backing, producing the Numericord controller. Numericord was similar to the MIT design, but replaced the punch tape with a magnetic tape reader that General Electric was working on. The tape contained a number of signals of different phases, which directly encoded the angle of the various controls. The tape was played at a constant speed in the controller, which set its half of the selsyn to the encoded angles while the remote side was attached to the machine controls. Designs were still encoded on paper tape, but the tapes were transferred to a reader/writer that converted them into magnetic form. The magtapes could then be used on any of the machines on the floor, where the controllers were greatly reduced in complexity. Developed to produce highly accurate dies for an aircraft skinning press, the Numericord "NC5" went into operation at G&L's plant at Fond du Lac, WI in 1955.

Monarch Machine Tool also developed an NC-controlled lathe, starting in 1952. They demonstrated their machine at the 1955 Chicago Machine Tool Show, along with a number of other vendors with punch card or paper tape machines that were either fully developed or in prototype form. These included Kearney & Trecker’s Milwaukee-Matic II that could change its plasma cutting machines tool under NC control.

A Boeing report noted that "numerical control has proved it can reduce costs, reduce lead times, improve quality, reduce tooling and increase productivity.” In spite of these developments, and glowing reviews from the few users, uptake of NC was relatively slow. As Parsons later noted:

    The NC concept was so strange to manufacturers, and so slow to catch on, that the US Army itself finally had to build 120 NC machines and lease them to various manufacturers to begin popularizing its use.

In 1958 the MIT published its report on the economics of CNC plasma cutter . They concluded that the tools were competitive with human operators, but simply moved the time from the machining to the creation of the tapes. In Forces of Production Noble claims that this was the whole point as far as the Air Force was concerned; moving the process off of the highly unionized factory floor and into the un-unionized white collar design office.

 

 

from:wiki