Jan 31, 2020 Viewed: 113 Tag: sheet metal   

Laser cutting machining sheet metal

In addition to the above-mentioned applications of laser cutting processing, some miniaturized plastic molds also use laser processing to stop carving and manufacturing, and laser carving, and the production quality is also quite high.

According to the basic processing method of sheet metal parts, metal laser engraving, such as blanking, bending, stretching, forming, and welding. According to the different processing methods, the blanking can be divided into ordinary punching, several punching, shearing, blanking, laser cutting, and wind cutting. Due to different processing methods, the processing technology of blanking is also different.

Sheet metal blanking methods are mainly punching and laser cutting and bending

When the data is curved, the outer layer is stretched and the inner layer is tightened on the rounded corners. When the thickness of the data is constant, the smaller the inner r, the more severe the tension and contraction of the data; when the tensile stress of the outer fillet exceeds the limit strength of the data, cracks and breaks will occur. The design should prevent excessively small bend fillet radii.

Stretching: The fillet radius between the bottom of the tensile part and the straight wall should be greater than the thickness of the plate, that is r1≥t. In order to make the drawing stop more smoothly, r1 = (3 ~ 5) t is generally adopted. The radius of the large fillet should be less than or equal to 8 times the thickness of the plate, that is, r1≤8t. Due to the different stresses on the stretched parts, the thickness of the stretched data will change.

1. The overall size of the processed product has changed

This is due to the influence of the diameter of the laser focal spot on the incision and the width of the incision formed by the extinguished area around it.

Although under the same conditions, the same offset compensation value can be used to ensure the accuracy of the same workpiece, but the setting of the focus position must be determined by the operator's perception, and the thermal lens will also form the focus position. Changes, so it is necessary to periodically check the optimal offset compensation value.

2. There is a difference in the dimensional error in the processing direction (local)

The dimensional accuracy of the upper part of the plate is different from the dimensional accuracy. This phenomenon needs to consider two reasons. First of all, the circularity and intensity of the beam are not uniformly distributed, and the width of the cut is different along the processing direction. The solution is to stop the optical axis adjustment or clean the optical components. Secondly, heat shrinkage of the workpiece causes a situation in which the dimension of the machined shape becomes shorter in the longitudinal direction.

3. Warped changes

Although the dimensional accuracy is within the required range, warpage may occur due to reasons such as thermal deformation. It is very significant when processing aluminum, copper, stainless steel, etc. It is affected by physical properties such as linear shrinkage coefficient and heat capacity. In terms of processed shapes, the greater the aspect ratio, the greater the amount of warpage. Low-heat processing conditions and processing lines are used to up and down the processing program, but the problem has not yet been completely solved.

The residual stress of the processed plate also affects the warpage and dimensional errors, so we need to adhere to a certain configuration direction for the processing program.

4. Pitch accuracy change

When machining many holes, the accuracy of the distance between the holes will be biased. Since the holes are opened under heat shrinkage, the distance becomes smaller after cooling and shrinking. We can correct the accuracy of the shrinkage in the program or use the shape scaling function sensitively. Regardless of the situation, after the initial processing, measure the processing size and compensate for the error. When the distance accuracy does not change with the processing position, but deteriorates in the entire processing area, the reason is caused by the deterioration of the mechanical accuracy.

5. Roundness change

It is impossible to prevent the slope of the cut surface of the hole during laser processing. The diameter of the lower side is larger than the diameter of the reverse side. Generally, the roundness of the side of the reverse side is slightly smaller.

AIXI presentation

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