Analysis of influencing factors of corrugation in sheet metal laser cutting
Sheet metal processing usually refers to a processing technology that cold-works metal sheets below 6mm. Sheet metal processing can usually be divided into stamping processing and CNC sheet metal processing. The former is suitable for mass production, and the latter is suitable for small batch production. This paper mainly analyzes and improves the influencing factors of cutting ripples in the process of sheet metal laser cutting and blanking in the case of small batch production.
Sheet metal processing is applied to a wide range of fields, such as chassis cabinets, home appliances, hardware products, instruments, billboards, lamps and other machinery manufacturing and processing industries. Its characteristics are that no additional tools are required, the processing speed is fast, the cycle is short, the surface deformation is small, and the types of materials that can be processed are various. In recent years, due to the need to adapt to the market demand of small batches and diversity, our company has begun to develop the optical disc library industry in order to expand the market area. The internal action components of the CD library are the core part of the entire CD library cabinet, and play a crucial role in the performance of the entire mechanism. The process dimensional accuracy of the core sheet metal products inside the cabinet is required to be ±0.1mm. Our company introduced a fiber laser stamping compound machine produced by Japanese equipment manufacturer AMADA, which is used for laser cutting and blanking of sheet metal products. The processing accuracy of this equipment is ±0.07mm/1000mm. Although the equipment has high precision, abnormal cutting phenomena, such as cutting ripples and cutting burrs, will still occur during the laser cutting and blanking process, and due to the particularity of the use of optical disc library products, these abnormal products will directly affect the action of internal components. Performance, abnormal products cannot be used, so the processing cost is directly increased. The comprehensive analysis and comparison of defective products found that cutting ripples mostly occurred on products with relatively large sizes, and the product defect rate was as high as about 10%, while the phenomenon of cutting ripples on smaller-sized products was less, and the product defect rate was less than 1%. . In order to reduce production losses and reduce processing costs, it is urgent to analyze and study the blanking process of laser cutting.
Status of cutting and blanking
When the composite machine is used for sheet metal laser cutting and blanking, the machine tool clamps move the plate along the X and Y directions. The product processing equipment and processing area are shown in Figure 1. However, with the continuous processing, the local stress of the plate is released, and the strength is gradually weakened, which causes the plate to shake during the movement process, resulting in laser cutting ripples, resulting in poor processed products. The size of the cutting corrugation is also related to factors such as the processing direction of the product, the initial processing position, and the order of taking out the product. And the large-sized product will have a larger stress release after being cut from the plate. Therefore, when the remaining part of the plate is cut, the plate will move with the clamp, and the shaking will be greater, resulting in cutting ripples when cutting the remaining product. Due to the large size of the product and the long processing time, the processing cost and material waste are more, so as much as possible to ensure the stability and strength of the force during the cutting movement of the plate is a key issue that needs to be considered in the cutting and blanking process. .
Figure 1 Processing equipment and processing area
Figure 2 Cutting corrugated state 1
Figure 3 Cutting corrugated state 2
Influencing factors of cutting corrugation
Product processing start position
During the cutting process, the processing starting position of the product plays an important role in the generation of cutting ripples. The starting position for machining is usually to start cutting from the end away from the clamp or from the end close to the clamp. When the product is processed from a position away from the clamp, as shown in Figure 4, the plate at the clamp end can be guaranteed to be cut at the end, which can well ensure that the plate stress is not released in advance, ensure the strength of the plate, and directly ensure that the plate is in Stability during movement to avoid cutting ripples. When the product is processed from a position close to the clamp, as shown in Figure 5, the stress of the plate has not been destroyed too much at the beginning of the processing, so the phenomenon of cutting corrugations usually does not occur, but as the processing continues, When the plate near the clamp end is continuously cut, the plate stress at the clamp end is gradually released, causing the plate to be "top-heavy" and greatly reducing the stability of the plate during movement. When the processing is gradually carried out in the direction away from the clamp, the peripheral products will inevitably cause cutting ripples due to insufficient strength of the plate. Therefore, in the programming process, it is necessary to ensure that the product starts to be cut from the end away from the clamp, and approaches the clamp end in turn, which can well ensure the strength of the plate and avoid the generation of cutting ripples.
Figure 4 The starting position for processing is good
Figure 5 Machining start position difference
Cutting entry point position and machining direction
In the process of sheet metal cutting, the cutting entry point will naturally become its return point. Choosing a reasonable entry point will reduce the probability of cutting ripples. At the beginning of processing, due to the good strength of the plate, the cutting entry point and processing direction will not have much influence on the cutting, but when the processing is nearing the end, for the remaining products to be processed, its entry point and processing direction will not have much influence. Orientation has an important effect on whether the cut produces ripples or not. It is necessary to ensure the strength of the product close to the clamp end, so as to better avoid the generation of cutting ripples. When the entry point is selected at the middle of the product, whether it is clockwise or counterclockwise cutting, the bottom of the product will be cut first, resulting in the release of sheet stress, the reduction of strength and stability, which will eventually lead to partial cutting of the product. generated, as shown in Figure 6. When the entry point is selected at the bottom end, the product is cut off at the end near the clamp, so that the stress of the plate is not released in advance, the movement is stable, and the probability of cutting ripples is greatly reduced, as shown in Figure 7. Of course, it is also necessary to select whether the entry point is at the bottom left or the bottom right according to clockwise or counterclockwise cutting. Therefore, when programming, regarding the selection of the cutting entry point and the processing direction, as long as the product is cut as close as possible to the end of the clamp and the movement distance is shorter, the generation of cutting ripples can be avoided to a certain extent.
Figure 6 Position difference of entry point
Figure 7 The position of the entry point is good
Clamp holding position
The function of the clamp is to clamp the plate to move in the X and Y directions with the processing program, and the second is to ensure the stability of the plate during processing. Therefore, it is necessary to reasonably distribute the position of the clamps to clamp the plate, so that the clamps are evenly distributed, so as to prevent the clamps from being deviated to one side, causing the plate to be unstable and shaking, resulting in the generation of cutting ripples. The comparison of the clamping positions of the clamps is shown in Figure 8. Although this factor has a certain influence on the cutting corrugation, it is an avoidable influencing factor during the operation.
Figure 8 Clamp holding position
Product take-out order
In the production process, the TK robot is sometimes used to assist in taking out the finished products, which can better save manpower and material resources and realize the fully automated production of the equipment. However, when using the TK manipulator to take out the products, it is necessary to pay attention to controlling the order of taking out the products to avoid the cutting ripples caused by the weakening of the strength of the plate and the shaking of the material. If you choose to take out the products at both ends of the plate first, and then take out the products in the middle of the plate, the stress at both ends of the plate will be released, and the strength of the plate will be insufficient. Shaking occurs, resulting in cutting corrugations of the product, as shown in Figure 9, and the product defect rate is high and the processing loss is large. If the products are taken out in sequence from the side away from the clamp, it can well ensure that the stress concentration of the sheet at the processing position, the movement is stable, and the cutting ripples are avoided, as shown in Figure 10. Therefore, during the processing and programming, it is necessary to ensure that the products to be taken out are carried out in sequence from the end away from the clamp, which can well ensure the strength of the plate and avoid the plate from shaking due to insufficient strength during the movement process, thereby avoiding the generation of cutting ripples.
Figure 9 Poor order of product removal
Figure 10 Good order of product removal
concluding remarks
The influencing factors of the above research are extended and shared based on the analysis of the current cutting ripples. The generation of cutting ripples is not caused by a certain factor, but is generated under the combined action of multiple factors, which has a certain relationship with the size, size, weight, processing speed, etc. of the product. In order to avoid the generation of cutting ripples, it is necessary to make comprehensive consideration in the programming process, so as to reduce the possibility of cutting ripples.
