Sheet metal processing usually refers to a processing process of cold processing of metal plates below 6mm.
Sheet metal processing can usually be divided into stamping processing and CNC sheet metal processing.
The former is suitable for mass production, while the latter is suitable for small batch production.
This post mainly analyzes and improves the influencing factors of cutting ripple in the process of sheet metal laser cutting and blanking in small batch production.
Sheet metal processing is applied in a wide range of fields, such as chassis and cabinets, home appliances, hardware products, instruments and meters, billboards, lamps and other machinery manufacturing and processing industries.
It is characterized by no need for additional tools, fast processing speed, short cycle, small surface deformation, and a variety of Machinable materials.
In recent years, due to the need to adapt to the market demand of small batch and diversity, our company began to develop the optical disk library industry in order to expand the market field.
The internal action component of the optical disk library is the core part of the whole optical disk library cabinet, which plays a vital role in the action performance of the whole mechanism.
The process dimension accuracy of the core sheet metal products inside the cabinet is required to be ± 0.1mm.
In order to ensure the processing accuracy, our company introduces the optical fiber laser stamping compound machine produced by Amada, a Japanese equipment manufacturer, for laser cutting and blanking of sheet metal products.
The processing accuracy of this equipment is ± 0.07mm/1000mm.
Despite the high accuracy of the equipment, abnormal cutting phenomena, such as cutting ripple, cutting burr and other problems, will still occur in the process of laser cutting and blanking.
Moreover, due to the particularity of the use of CD-ROM products, these abnormal products will directly affect the action performance of internal components, and the abnormal products cannot be used, which directly increases the processing cost.
Through comprehensive analysis and comparison of defective products, it is found that the cutting ripple mostly occurs on products with relatively large size, and the product defect rate is as high as about 10%, while the cutting ripple phenomenon is less for products with small size, and the product defect rate is less than 1%.
In order to reduce production losses and processing costs, it is urgent to analyze and study the laser cutting blanking process.
Cutting and blanking status
When the compound machine is used for sheet metal laser cutting and blanking, the machine clamp holds the sheet metal and moves along the X direction and Y direction.
The product processing equipment and processing area are shown in Fig. 1.
However, with the continuous processing, the local stress of the plate is released, and the strength gradually weakens, resulting in the shaking of the plate in the process of movement, resulting in laser cutting ripples, resulting in poor processed products.
The size of the cutting ripple is also related to the processing direction of the product, the initial processing position, the removal order of the product and other factors.
The bad cutting ripple phenomenon under different conditions is shown in Fig. 2 and Fig. 3.
And the stress release of large-size products will be greater after cutting from the plate. Therefore, when cutting the remaining part of the plate, the plate will move with the clamp, and the shaking will be greater, resulting in cutting ripples when cutting the remaining products.
Due to the large size of the product and the long processing time, there is a lot of processing cost and material waste.
Therefore, it is important to ensure the stability and strength of the plate during the cutting process as much as possible.
Fig. 1 processing equipment and processing area
Fig. 2 cutting ripple state 1
Fig. 3 cutting ripple state 2
Influencing factors of cutting ripple
Starting position of product processing
During cutting, the starting position of products plays an important role in the generation of cutting ripples.
The starting position of machining is usually from the end away from the clamp or from the end close to the clamp.
When the product is processed from a position far away from the clamp, as shown in Fig. 4, the plate at the clamp end can be cut at last, which can well ensure that the plate stress is not released in advance, ensure the strength of the plate, directly ensure the stability of the plate in the process of movement, and thus avoid cutting ripple.
When the product is processed from the position close to the clamp, as shown in Fig. 5, the plate stress has not been destroyed too much at the beginning of processing, so the phenomenon of cutting ripple usually does not occur.
However, with the continuous processing, when the plate close to the clamp end is continuously cut, the plate stress at the clamp end is gradually released, resulting in the plate “top heavy”, which greatly reduces the stability of the plate in the process of movement.
When the processing is gradually carried out away from the clamp, the peripheral products are bound to produce cutting ripples due to the insufficient strength of the plate.
Therefore, in the process of programming, it is necessary to ensure that the products are cut from the end far away from the clamp and close to the clamp end in turn, so as to ensure the strength of the plate and avoid the generation of cutting ripples.
Fig. 4 good starting position of processing
Fig. 5 processing start position is poor
Cutting 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 cutting point will reduce the probability of cutting ripple.
At the beginning of processing, due to the good strength of the plate, the cutting point and processing direction will not have much impact on the cutting, but when the processing is close to the end, for the remaining products to be processed, the cutting point and processing direction have an important impact on whether the cutting produces ripples.
Ensure the strength of the products close to the clamp end, so as to better avoid the generation of cutting ripples.
When the cutting point is selected in the middle of the product, whether cutting clockwise or anticlockwise, the bottom of the product will be cut first, resulting in the stress release of the plate, the strength reduction, the stability reduction, and finally the local cutting ripple of the product, as shown in Fig. 6.
When the cutting point is selected at the bottom end, the product close to the clamp end is finally cut off, so that the plate stress is not released in advance, the movement is stable, and the probability of cutting ripple will be greatly reduced, as shown in Fig. 7.
Of course, whether the cutting point is at the bottom of the left side or the bottom of the right side should also be selected according to clockwise cutting or counterclockwise cutting.
Therefore, when programming, as for the selection of cutting point and processing direction, as long as it is possible to ensure that the product is finally cut off near the clamp end, and the shorter the moving distance, the more cutting ripples can be avoided to a certain extent.
Fig. 6 The position of the cutting point is poor
Fig. 7 the position of the cutting point is good
Clamp clamping position
The function of the clamp is to clamp the plate to move in the X and Y directions with the processing program, and to ensure the stability of the plate during the processing operation. Therefore, it is necessary to reasonably distribute the positions of the clamps holding the plates, so that the clamps are evenly distributed, so as to avoid the unstable shaking of the plates caused by the deflection of the clamps to one side and the generation of cutting ripples.
The comparison of clamp clamping positions is shown in Fig. 8.
Although this factor has a certain impact on the cutting ripple, it is an avoidable factor in the operation process.
Fig. 8 Clamp clamping position
Product removal sequence
In the production process, TK manipulator is sometimes used to assist in taking out the cut products, which can better save human and material resources and realize the fully automated production of the equipment.
However, when using TK manipulator to take out products, attention should be paid to controlling the taking out sequence of products to avoid cutting ripples caused by weakening of strength and shaking of materials.
If the products at both ends of the plate are taken out first, and then the products in the middle of the plate are taken out, the stress at both ends of the plate will be released, and the plate strength will be insufficient.
When the processing program reaches the middle position of the plate, the plate will inevitably shake due to insufficient strength, resulting in the cutting ripple of the products, as shown in Fig. 9, and the product defect rate is high, resulting in large processing losses.
If the products are taken out successively from the side away from the clamp, it can well ensure that the stress concentration of the plate at the processing position, the movement is stable, and the cutting ripple is avoided, as shown in Fig. 10.
Therefore, during processing and programming, it is necessary to ensure that the products taken out are carried out in sequence from the end away from the clamp, so as to ensure the strength of the plate and avoid the shaking of the plate due to insufficient strength during the movement, so as to avoid the generation of cutting ripples.
Fig. 9 poor product removal sequence
Fig. 10 good product removal sequence
The influencing factors of the above research are based on the analysis of the cutting ripple at this stage.
The generation of cutting ripple is not affected by a certain factor, but by the joint action of multiple factors, which has a certain relationship with the size, size, weight, processing speed and so on.
To avoid the generation of cutting ripples, we need to make a comprehensive consideration in the programming process, so as to reduce the possibility of cutting ripples.