Views: 46 Author: Durmapress Publish Time: 2020-08-06 Origin: Durmapress
What are the applications of CNC press brakes in the sheet metal bending process in the production of special vehicles?
Today, I will mainly talk about some applications of sheet metal bending technology in the production of special vehicles.
Review elements of bending process
In order to standardize the application of the bending process in production, strict and detailed special vehicle bending design process evaluation standards have been formulated, and the product design is closely cooperated to optimize the parts in the early design stage, such as the r-bending angle Radius, r1—one-time bending angle radius, α—bending angle angle, t—sheet thickness, V—bending opening width, L—bending linear length, W—minimum reserved length for second bending, a —Bending length, b—the length of the middle section of the secondary bending, T—100 ton Hydraulic (CNC) Press Brake tonnage, R—box bending corner radius and other related standards have made relevant regulations, which effectively solves the irrationality of related designs And the change cycle, to the greatest extent to ensure the manufacturability of the product.
Selection of bending tools
The upper die of the 100 ton Hydraulic Press Brake is mainly divided into three categories: straight knife, scimitar, and sharp knife.
(1) Considering the structure of the product comprehensively, we have equipped with two types of upper molds, scimitar and straight knife. The straight knife of 10' x 100 Ton Press Brake is mainly used for smaller bending parts on the car body, and the scimitar is used for complex structures and more than twice. Bending parts that interfere with the tool can meet the bending needs of special equipment.
(2) The lower mold adopts a V-shaped groove, and we basically use V=6 times the material thickness to determine the width of the V port. The process should be based on the actual product output and production frequency to arrange the V ports of the V-shaped grooves in a reasonable manner, so that the number of mold changes on the same equipment can be minimized during production, production efficiency, and mold replacement costs are reduced; Put the most commonly used V=9mm V port on the main working surface of the lower mold. At the same time, you can also place several spare common V ports on the secondary working surface to make reasonable use of the lower mold to maximize the service life of the mold.
Special mold maintenance
The maintenance of special vehicle bending molds is based on the special needs of the Press Brake 100 Ton . The maintenance requirements are higher than those of ordinary products. The maintenance cycle, maintenance items, and replacement cycle must be strictly regulated. The long-term production of bending tools will inevitably produce irreversible Wear and tear, causing quality problems such as the bending opening, angle, straightness and external surface indentation of the workpiece. The actual experience of working face grinding is generally not more than 3 times. Considering the production cost, the preventive maintenance thinking should be adopted in the production. Parts or other factors reduce the consumption of molds to a minimum. The more common requirements we adopt mainly include: tool status check, part process check, pay attention to the quality of part section cutting, and reduce foreign matter damage to the tool.
Measures to ensure the dimensions of bending parts
The current common structure of special vehicles is a frame structure plus a skin structure. The car body is mainly composed of laser cutting parts, bending parts, and stamping parts. The subsequent welding methods are also different according to the material and protection needs. Therefore, the frame size must be strictly guaranteed at the initial stage of manufacture, and the diagonal error shall not be greater than 4mm. This also puts forward higher dimensional accuracy requirements for the outer surface car body bending parts. The angle, flange size, straightness, and outer surface quality of the corresponding bending parts must also be strictly controlled.
During the bending process of special material sheet metal, we often encounter springback problems due to the special properties of the sheet metal, and plastic deformation and elastic deformation exist at the same time. At the end of bending, springback occurs due to the recovery of elastic deformation. The springback phenomenon directly affects the dimensional accuracy of the workpiece and must be controlled. The technological measures taken for this are: angle compensation method, if the bending angle of the workpiece is 90°, the opening angle of the lower groove (V-shaped) of the press brake can be 78°, or the angle can be compensated during programming according to actual data; also The pressurizing time increase correction method can be used to perform pressurization correction at the end of the bending, to extend the contact time of the upper die, workpiece, and lower groove of the press brake, so as to increase the degree of plastic deformation at the fillet of the lower groove, so that the fiber in the tension and compression zone The rebound trends resist each other, thereby reducing rebound. At the same time, it is recommended to record and verify each round of data during the formulation of any kind of process parameters, which is conducive to the stability of the later production process
Related to the bending problem of the bending parts, you can adjust the inner and outer directions of the shearing surface of the sheet. The workpiece is deburred before bending, and the broken part can be polished with a manual grinder after bending. For different workpieces, the process should be refined, the assembly size relationship should be understood, and the bending sequence should be set correctly.
At the same time, in order to ensure the size of the bending parts, the main positioning method we use is to use the edge positioning of the numerical control block and the positioning hole positioning. The two positioning methods have their own advantages and disadvantages: the production efficiency of side positioning is fast, and it can be pushed continuously, but the side positioning depends on the accuracy of cutting or blanking. Once the sheet has beveled edges or other poor cutting, it will directly affect To the bending accuracy; and the hole positioning reduces the dependence on the sheet material, and the positioning holes are artificially added to the workpiece, but different types of bending molds need to be debugged multiple times, which appears to be in the production of multiple varieties and small batches low efficiency. Therefore, for different bending parts, we must confirm the functions of the corresponding parts of the size in actual production, so as to determine whether it is continuous pushing or turning bending. The corresponding guaranteed accuracy produced by these two bending methods is also different. of. In addition, all special equipment bending parts are inspected according to process requirements.