A laser is a kind of light enhanced by stimulating radiation.
Due to their good directivity, high brightness and good monochromaticity, lasers are widely used in laser cutting, laser welding, laser engraving, laser drilling, laser marking, etc. Laser applications have also risen to the top of the most promising fields right now.
Let us now look at how laser cutting technology is used in the car industry.
Principles and Advantages of Laser Cutting
Laser cutting is the use of high power density laser beam to scan the material surface, heat the material to thousands to tens of thousands of degrees Celsius in a very short time, melt or vaporize the material, and then use high pressure gas to blow the melted or vaporized material away from the cutting seam, to achieve the purpose of cutting.
The advantages of laser cutting in car parts fabrication are as follows:
(1) High precision, with a positioning accuracy of about 0.05mm.
(2) Narrow slit where the laser beam is focused into a small spot, allowing the focal point to reach high power density.
The material is heated to vaporization and evaporates to form a whole.
With the relative linear motion of the beam and the material, the hole continuously forms a slit of very narrow width.
(3) The cutting surface should be smooth and burr-free.
(4) Fast speed, much faster than wire cutting speed.
(5) Good cutting quality, non-contact cutting; small thermal impact on the cutting edge; workpiece basically no thermal deformation; completely avoid the edge collapse formed when the material punching and shearing, cutting joints generally do not require secondary processing.
(6) There is no harm to the workpiece because the laser cutting head does not touch its surface, ensuring that it is not damaged.
(7) Regardless of the cutting material’s hardness, a laser can process steel plate, stainless steel, aluminium alloy plate, hard alloy plate, and other materials.
(8) It has good elasticity and is unaffected by the shape of the workpiece.
Tubes and various profiles can be cut, and any shape can be treated.
(9) Save the investment of tooling.
Laser processing does not need moulds; there is no mould loss, no need to repair moulds, saving the time of mould replacement, thus saving processing costs and reducing production costs.
(10) Save material, use computer programming to cut the whole board for different shapes, and improve the material utilisation rate.
(11) It has the potential to reduce the time it takes to develop new items.
New product trial production is typically limited in scale and has a shaky framework. There is no need to manufacture moulds, which reduces waste and shortens the production cycle of new products.
(12) Non-metallic materials can be cut.
As a result, using this equipment in production is highly viable. This equipment is also suitable for producing small quantities of workpieces, which provides convenience and cost savings for the pre-production and development of parts.
Laser Cutting Equipment
There are many types of laser cutting equipment.
- Two-dimensional laser cutting machine, mainly used for cutting flat workpieces.
- Three-dimensional laser cutting machines can cut workpieces in three dimensions.
- Laser cutting robots (Figure 1) can cut more complex three-dimensional workpieces.
With the development of the automotive industry, laser cutting robots are increasing, and this laser cutting machine can also cut flat workpieces and simple three-dimensional workpieces.
Therefore, the following section focuses on the laser cutting robot workstation components.
Components of the laser cutting robot workstation.
- High-precision trajectory robot achieves high precision, high speed, three-dimensional processing, and cost reduction.
- The equipment that generates a laser source is the laser generator, which includes solid-state laser generators, gas laser generators, and fiber laser generators.
- The laser generator is cooled using a cooler.
- Fiber optic cable.
- Cutting head, mainly including cavity, focusing mirror holder, focusing mirror, capacitance sensor, auxiliary gas nozzle and other parts.
- The table is used to place the workpiece to be cut and can be moved correctly and accurately according to the control program. A servo motor drives it.
- CNC control system controls the table to realize the movement of the X, Y and Z axes and controls the output power of the laser.
- The operation table is used to control the whole working process of the cutting device.
- Gas cylinder, including the working medium gas cylinder and auxiliary gas cylinder of the laser cutting machine.
- Air compressor.
- Air cooling dryer and filter.
- Auxiliary equipment, such as exhaust fans and dust collectors.
Practical Applications of Laser Cutting Robots in Automotive Manufacturing
Laser cutting robots are used in automotive parts processing as follows.
Cutting of Pipe Parts
The portion is laser cut with all of the holes on the pipe, as shown in Figure 2. (4 holes on the left side and 5 holes on the right side).
Due to a large number of holes and different sizes of holes, if punching is done with moulds, the moulds are more complicated, the number of moulds is more, the investment is larger, and the frequency of mould maintenance at the later stage is also high, which will take up a lot of time and manpower to produce unqualified products and affect the quality of the parts.
There should also be special quality inspectors for inspection to prevent unqualified products from flowing out.
Adopting laser cutting technology can reduce a large amount of capital investment in tooling and bring the following benefits.
(1) Ensure the quality of the parts.
The parts are precisely cut, and this non-contact manufacturing eliminates the possibility of collapsed corners.
(2) Save the occupancy of operators and equipment.
After adjusting the program, when laser cutting is used, only one worker can complete a series of work such as picking up, loading, and unloading the parts.
If die is used to achieve this, at least 3 sets of dies, 3 operators and 3 sets of stamping equipment are needed.
(3) Save time and easy to operate.
According to practice, 400 sets of parts can be cut daily, and workers will not be too tired and efficient.
If using dies, 400 sets can be produced in a day under normal circumstances.
If there is an issue with the mould, however, fixing, installing, and debugging it will take a lot of time and work.
(4) Avoid missed and wrong cuts.
If there is a missed or wrong cut in laser cutting, the equipment will send out an alarm, and there will be no unqualified products out.
If there is a missed punch in the die, it is not easy to be detected. In this way, the outflow of non-conforming products will bring more losses.
To assure the parts’ quality, the positioning of the pieces must be precise. Hence a part positioning fixture is created (Figure 3).
The fixture is divided into three sections.
(1) The fixing plate is fixed to the workstation table with screws and pins.
The fixed positions on the workbench have screws and pins, so the fixture’s design should be combined with the dimensions of the workbench and not designed blindly.
(2) The position between the hole and the end of the part is the most crucial for the positioning device of the part. Thus the positioning is set at the end of the part, according to the usage characteristics.
(3) For the clamping device of the part, the part needs to turn over with the table because the part has cutting parts in all directions.
Four sets of clamping cylinders are required to prevent the part from falling off when the table is turned.
Generally speaking, the fixture is simple in structure, easy in operation and low in investment cost, but it can bring great benefits and can be said to be more practical.
Cutting the Profile
As shown in Figure 4, the part requires cutting two large holes and two ends.
When holes and ends are punched with a die, they are deformed.
Therefore, to ensure the quality of the part, laser cutting is used to avoid distortion of the part.
The cutting of the part holes is relatively easy to achieve, but it is more difficult to cut the ends of the profile.
The profile has a B-shaped section, and the cutting direction is 360 degrees in all directions.
As a result, the laser cutting head must be able to rotate 360 degrees, and there must be sufficient room for the cutting head to spin.
If there is not enough space in the normal direction, then small-angle cutting can be used without affecting the use of the part.
Therefore, the cutting trajectory setting of the cutting head needs to be tried continuously to ensure the quality of the part, reduce the cost of the part and improve productivity.
The laser cutting fixture for the part is shown in Figure 5.
The structure of this fixture is similar to the pipe fixture and is also divided into three parts.
(1) The fixing plate is fixed in the same way as the fixing plate of the pipe.
(2) The part placement device has two critical mounting holes.
Therefore, hole positioning is used to make the position of the part accurate.
The positioning structure uses a cylinder to drive the positioning pin, which can be moved back and forth to facilitate the pick and place of the workpiece.
(3) The component’s clamping device is identical to the pipe part. However, the clamping head differs depending on the part’s shape.
Compared to the mould in the previous two cases, the laser cutting fixture is rather simple, consisting of three parts: a mounting plate, a positioning device, and a clamping device.
Also, it shows that the application of laser cutting robots can solve many problems and bring many benefits to automotive parts manufacturing.
In summary, laser cutting has outstanding advantages in automotive processing, which adapts to the development trend of reducing cost and improving the quality of automobiles. Moreover, the application of laser processing robot workstations in the automotive industry is becoming more and more widespread, not only in laser cutting, laser welding, laser marking, laser engraving, etc. but even in non-metallic materials is very common.