Plasma cutting

Jan 25, 2010 at 09:43 o\clock

Plasma and Laser Technologies Applied To Industrial Metal Cutting

by: sanben   Keywords: Plasma, cutting, machine

Plasma Cutting - a technology that grew out of plasma welding in the 1960s - emerged as a very productive way to cut sheet metal and plate in the 1980s. It had the advantages over traditional "metal against metal" cutting of producing no metal chips and giving accurate cuts, and produced a cleaner edge than oxy-fuel cutting. Early plasma cutters were large, somewhat slow and expensive and, therefore, tended to be dedicated to repeating cutting patterns in a "mass production" mode.

As with other machine tools, CNC plasma (computer numerical control) technology was applied to plasma cutting machines in the late 1980s into the 1990's, giving plasma cutting machines greater flexibility to cut diverse shapes "on demand" based on a set of instructions that were programmed into the machine's numerical control. These CNC plasma cutting machines were, however, generally limited to cutting patterns and parts in flat sheets of steel, using only two axes of motion (referred to as X Y cutting).

Industrial laser technology followed a commercialization path for industrial use similar to that of plasma, but roughly a decade later. Industrial laser cutting technology for metals has the advantages over plasma cutting of being more precise and using less energy when cutting sheet metal, however, most industrial lasers cannot cut through the greater metal thickness that plasma can. Newer lasers machines operating at higher power (6000 watts, as contrasted with early laser cutting machines' 1500 watt ratings) are approaching plasma machines in their ability to cut through thick materials, but the capital cost of such machines is much higher than that of plasma cutting machines capable of cutting thick materials like steel plate.

The majority of industrial laser cutting machines are also used to cut flat materials, using two axes of motion for the cutting head.
Starting in the late 1990s, programmable industrial robots were integrated with plasma and laser cutting to allow these metal cutting technologies to be applied to more generalized cutting of non-flat shapes. These "3D Systems" use the industrial robot to move the laser or plasma cutting head around the element to be cut, so that the cutting path may encompass the entire outer surface of the element. Many systems also grip the element to be cut in a "chuck" so that the element itself can be rotated or indexed forward or backward in concert with the movement of the cutting head. This serves to decrease overall cutting time and increase accuracy by optimizing the motion of the element with the motion of the cutting head.

Robotic 3D laser cutting systems frequently make use of this technique of moving the element to be cut, because laser systems work well with smaller thin-wall elements such as tubes. As OD and wall thickness of the pipe/tube increases, 3D laser cutting becomes less attractive due to the increased cutting time and higher capital cost of laser cutting technology.

Robotic plasma cutting is more widely used for 3D cutting of pipe, including HSS, used as structural steel elements. Vernon Tool Company was an early innovator in developing 3D plasma cutting machinery for oil/gas field and structural tube/pipe. Similar systems introduced by QuickPen, Watts Specialties and Bickle Manufacturing are capable of cutting pipe diameters up to 32 inches and making straight, angled and saddle cuts, including beveled-edge cuts needed for joining together different pipes.

The task of robotic plasma cutting of more diverse shapes, such as beams and channels, has proven to be more challenging. The large sizes and variety of shapes involved make the technique of gripping the structural steel element in a chuck impractical. This places the entire burden of cutting motion back on the robot. In order to have the cuts and features placed where they are intended on the element, the robot must be given some instruction as to the location, size and shape of the element.

Burlington Automation developed software capable of reading CAD drawings of the structural element, and combining this information with motion control and sensor feedback to arrive at a 3D plasma cutting system that in effect "sees" the structural steel element it is to cut. There are no vision systems involved, rather the robotic arm that carries the plasma torch head gently touches (probes) the element to be cut in multiple locations and combines this information along with the CAD drawing data to determine the exact contours of the element in three dimensions. With this information, the robotic plasma cutting system, which goes by the trade name PythonX is able to cut a variety of features (bolt holes, copes, notches) or marks into exact locations along the structural elements. This extends the automated 3D plasma cutting machine capability pioneered by Vernon Tool and others to the complete range of structural steel elements, thus allowing the PythonX system to replace beam drill lines, coping machines, bandsaws and plate burning centers.

If the past is prologue, it might be expected that robotic 3D laser cutting technology will soon be commonly applied to the fabrication of structural steel elements, as has already been done with plasma cutting. The steel thickness limitation of laser cutting has been overcome by the evolution of more powerful laser systems. However, as a general rule, tolerances on structural steel elements are less exacting than for other manufactured steel goods (such as auto components), therefore the extra precision that laser cutting offers is typically not required for structural steel. Areas of exception may be structural elements for ships and large, highly customized fabrications for power plants. For the time being, the lower capital cost and higher cutting speeds of robotic 3D plasma cutting make it the technology of choice for generalized fabrication of structural steel elements.

 

from:wiki

Jan 25, 2010 at 09:36 o\clock

In recent years, developments in Plasma Cutting Machine

by: sanben   Keywords: Plasma, Cutting, Machine

Fabrication of dimensional (non-flat) structural steel elements has historically been performed by sequential operations involving sawing, drilling and high temperature flame cutting to remove material. Each of these operations is performed on special purpose machinery; hence the time involved in loading/unloading and transporting the structural steel elements between machines can add considerable time to the total fabrication process.

In recent years, developments in Plasma Cutting Machine and laser cutting of metals have been combined with computer motion control to accomplish the sequential operations on a single machine. This has the advantage of minimizing the non-productive loading/unloading/transport time, and can also improve dimensional accuracy of the fabricated element, due to the use of position sensors and highly accurate servo motor drives to position the cutting head or "torch" of the machine.

Structural steel is often thought of as the "skeleton" of multi-story construction, in that it provides the framework upon which floor, wall and exterior cladding systems are affixed. Individual pieces of structural steel (interchangeably called elements, sections or members) are produced in steel mills or foundries,conforming to chemical composition and geometric/dimensional specifications established by regulatory agencies and industry associations, such as the American Institute of Steel Construction.

The most common structural steel elements are beams (also known as I-beams, H-beams or girders), channels, HSS (for hollow structural shapes), angles, columns and plate. These elements are cut to required lengths and joined together, either by welding or mechanical fastening (bolting) in the manner prescribed to achieve the objectives for supporting both static and dynamic loads.

Fabrication (cutting and drilling features) of structural steel elements has always been performed using "metal against metal" techniques, and these remain the most widespread fabrication methods today. The emergence of CNC (computer numerical control) technology brought automation and greater accuracy to these techniques, resulting in families of special purpose machines dedicated to performing individual fabrication tasks.
Perhaps the most common such machine is the bandsaw. A bandsaw employs a continuously rotating band of toothed metal to saw through the structural steel and is generally used to cut through the entire cross section of the element to achieve the prescribed length.

A beam drill line (drill line) has long been considered an indispensable way to drill holes and mill slots into beams, channels and HSS elements. CNC beam drill lines are typically equipped with feed conveyors and position sensors to move the element into position for drilling, plus probing capability to determine the precise location where the hole or slot is to be cut.

For plasma cutting irregular openings or non-uniform ends on dimensional (non-plate) elements, a cutting torch is typically used. Oxy-fuel torches are the most common technology and range from simple hand-held torches to automated CNC 'coping machines' that move the torch head around the structural element in accordance with cutting instructions programmed into the machine.

Fabricating flat plate is performed on a plate processing center where the plate is laid flat on a stationary 'table' and different cutting heads traverse the plate from a gantry-style arm or "bridge." The cutting heads can include a punch, drill or torch.

 

from:wiki

Jan 19, 2010 at 02:58 o\clock

TDC Flange Forming Machine

by: sanben   Keywords: Flange, Forming, Machine

 

TDC unit is one of the two universal flange making systems 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| Flange Forming Machine

Jan 19, 2010 at 02:49 o\clock

Plasma Cutter and CNC cutting methods

by: sanben   Keywords: Plasma, Cutter

The HF Contact type typically found in budget machines uses a high-frequency, high-voltage spark to ionise the air through the torch head and initiate an arc. These require the torch to be in contact with the job material when starting, and so are not suitable for applications involving CNC cutting.

The Pilot Arc type uses a two cycle approach to producing plasma, avoiding the need for initial contact. First, a high-voltage, low current circuit is used to initialize a very small high-intensity spark within the torch body, thereby generating a small pocket of plasma gas. This is referred to as the pilot arc. The pilot arc has a return electrical path built into the torch head. The pilot arc will maintain itself until it is brought into proximity of the workpiece where it ignites the main plasma cutting arc. Plasma arcs are extremely hot and are in the range of 15,000 degrees Celsius.

Plasma is an effective means of cutting thin and thick materials alike. Hand-held torches can usually cut up to 2 in (48 mm) thick steel plate, and stronger computer-controlled torches can pierce and cut steel up to 12 inches (300 mm) thick. Formerly, plasma cutters could only work on conductive materials; however, new technologies allow the plasma ignition arc to be enclosed within the nozzle, thus allowing the cutter to be used for non-conductive workpieces such as glass and plastics.

Since plasma cutting machine produce a very hot and very localized "cone" to cut with, they are extremely useful for cutting sheet metal in curved or angled shapes.
Analog plasma cutters, typically requiring more than 2 kilowatts, use a heavy mains-frequency transformer. Inverter plasma cutters rectify the mains supply to DC, which is fed into a high-frequency transistor inverter between 10kHz to about 200kHz. Higher switching frequencies give greater effiencies in the transformer, allowing its size and weight to be reduced.

The transistors used were initially MOSFETs, but are now increasingly using IGBTs. With paralleled MOSFETs, if one of the transistors activates prematurely it can lead to a cascading failure of one quarter of the inverter. A later invention, IGBTs, are not as subject to this failure mode. IGBTs can be generally found in high current machines where it is not possible to parallel sufficient MOSFET transistors.

The switch mode topology is referred to as a dual transistor off-line forward converter. Although lighter and more powerful, some inverter plasma cutters , especially those without power factor correction, cannot be run from a generator (that means manufacturer of the inverter unit forbids doing so; it is only valid for small, light portable generators). However newer models have internal circuitry that allow units without power factor correction to run on light power generators.
Plasma cutters have also been used in CNC (computer numerically controlled) machinery. Manufacturers build CNC cutting tables, some with the cutter built in to the table. The idea behind CNC tables is to allow a computer to control the torch head making clean sharp cuts. Modern CNC plasma equipment is capable of multi-axis cutting of thick material, allowing opportunities for complex welding seams on CNC welding equipment that is not possible otherwise. For thinner material cutting, plasma cutting is being progressively replaced by laser cutting, due mainly to the laser cutter's superior hole-cutting abilities.

A specialized use of CNC Plasma Cutters has been in the HVAC industry. Software will process information on ductwork and create flat patterns to be cut on the cutting table by the plasma torch. This technology has enormously increased productivity within the industry since its introduction in the early 1980s.

In recent years there has been even more development in the area of CNC Plasma Cutting Machinery . Traditionally the machines' cutting tables was horizontal but now due to further research and development Vertical CNC Plasma Cutting Machines are available. This advancement provides a machine with a small footprint, increased flexibility, optimum safety, faster operation, energy efficiency, ergonomic and more environmentally friendly.

Plasma torches were once quite expensive. For this reason they were usually only found in professional welding shops and very well-stocked private garages and shops. However, modern plasma torches are becoming cheaper, and now are within the price range of many hobbyists. Older units may be very heavy, but still portable, while some newer ones with inverter technology weigh only a little, yet equal or exceed the capacities of older ones.

 

from:SBKJ|Plasma Cutting Machine

Jan 12, 2010 at 06:42 o\clock

Tube forming for building

by: sanben   Keywords: tube, former

In structural engineering, the tube is the name given to the systems where in order to resist lateral loads (wind, seismic, etc.) a building is designed to act like a three-dimensional hollow tube, hence the name, cantilevered perpendicular to the ground. The system was introduced by Fazlur Rahman Khan while at Skidmore, Owings and Merrill's (SOM) Chicago office. The first example of the tube’s use is the 43-story Khan-designed DeWitt-Chestnut Apartment Building in Chicago, Illinois, completed in 1963.

The system can be constructed using steel, concrete, or composite construction (the discrete use of both steel and concrete). It can be used for office, apartment, and mixed-use buildings. Most buildings in excess of 40 stories constructed in the United States from the period after World War II to the 1990s were of this structural type. It is slowly being overtaken by the use of core-supported type structures.
The tube system concept is based on the idea that a building can be designed to resist lateral loads by designing it as a hollow cantilever perpendicular to the ground. In the simplest incarnation of the tube, the perimeter of the exterior consists of closely spaced columns that are tied together with deep spandrel beams through moment connections. This assembly of columns and beams forms a rigid frame that amounts to a dense and strong structural wall along the exterior of the building.

This exterior framing is designed sufficiently strong to resist all lateral loads on the building, thereby allowing the interior of the building to be simply framed for gravity loads. Interior columns are comparatively few and located at the core. The distance between the exterior and the core frames is spanned with beams or trusses and intentionally left column-free. This maximizes the effectiveness of the perimeter tube by transferring some of the gravity loads within the structure to it and increases its ability to resist overturning due to lateral loads.

 

 

 

 
 

 

The module technique gives the customer the possibility to choose
between a number of options, allowing him to create a machine a number of options, allowing him to create a machine for his specific needs.
The frequency controlled main drive ensures a smooth acceleration and an almost noiseless operation.
 The outstanding patented flying slitter cuts the tubes to lengthwithout noise or hot sparks as known from the saws and provides smooth tube ends without deburring.
The design and options fulfill the needs in HVAC to produce in mild steel, galvanized steel, stainless steel or aluminum
 The corrugation unit allows a reduction in material costs and makes the bigger diameter tubes more rigid.
 
Main Technical Date:

 

Diameter range
80 – 1600mm
Thickness of strip
0.4 -1.3mm Glvanized steel
0.8mm Sinless steel
0.4-1.2mm Auminum
 
Strip Width
standard 137mm up to 1mm
thickness, 140mm above. Other widths on request.
Lockseam
Outside tube, on the inside on request.
Production speed
Max. 60 meters/min. depending on material
Cutting system
The pqtented flying slitter
Net weight
2900kg
Gross weight
3200kg
Machine dimension
3000mm*1950mm*1700mm,
Package dimension
3050mm*2000mm*1800mm
Options
Automatic length control system, controlled corrugation unit.METU flange slitter Saw blade cutter
 
 
 

 

Jan 5, 2010 at 09:39 o\clock

Square Duct is mainly used for air duct

by: sanben   Keywords: Square, Duct

Square Duct is mainly used for air duct,and it has several obvious advantages against previous rectangular duct:
First,it can increase the strength, because every bite there is strengthening rib.
Second,High efficiency, feed speed of 38 meters per minute is impossible for rectangular duct production;
Third,Reduce consumption and save energy:It is of vortex shape when the air pass from the duct,using the sprial duct can reduce resistance.Morever,cleaning is very convenient because there are professional cleaning tools and no dirt corners on the inner wall of the Spiral Tubeformer with outside corrugations and outside lock seam.
So it can not only save material, to be very economical, but also can improve the air flow.

There are two distinguishing  products of SBKJ:
One is flying shear type sprial tubeformer,model:SBTF- 1602 tube machine.What are the advantages of it?
First,as use of the stable forming dies,there is no size bias in the operation.The other advantage is that there are hardly scratches on the surface, so the it can satisfy the high requirements of places like airport and clean room.
Another product SBTF-1500D  tube former with a big technology breakthrough.It increases a roll-type cutting shear on the basis of our previous product SBTF-1500 pipe machinery.The advantage is:
no need of forming dies
can produce pipe between diameter 80mm and 1500mm with the change of one metal band
the breakthrough is the roll-type cutting shear,no noise and no scratche 

 

 

 

The module technique gives the customer the possibility to choose
between a number of options, allowing him to create a machine a number of options, allowing him to create a machine for his specific needs.
The frequency controlled main drive ensures a smooth acceleration and an almost noiseless operation.
 The outstanding patented flying slitter cuts the tubes to lengthwithout noise or hot sparks as known from the saws and provides smooth tube ends without deburring.
The design and options fulfill the needs in HVAC to produce in mild steel, galvanized steel, stainless steel or aluminum
 The corrugation unit allows a reduction in material costs and makes the bigger diameter tubes more rigid.

 

from:sbkj