Views:140 Author:Site Editor Publish Time: 2020-08-04 Origin:Site
Medium and thick plates are widely used in various fields as stress parts, such as bulldozers, excavators, loaders, railway passenger cars, and other construction machinery and locomotives. Medium and heavy plates usually refer to metal plates with a thickness between 4.5 and 25mm. The forming methods of medium and heavy plates mainly include: press brake bending forming, rolling machine forming, and press tolling forming. Bending(folding ) is a widely used and abundant product line forming method for the medium and thick plates.
The difficulties of plate bending are long workpieces, high pressure, difficult forming, low efficiency, and difficult to control precision. The final result of bending is a comprehensive reflection of material parameters, process parameters, and mold parameters. Reasonable design of these parameters is the key to improving the bending performance of medium and thick plates.
The first problem facing medium and thick plate bending is the tonnage selection of the press brake bending machine, and whether the bearing capacity of the fixture and the mold meets the requirements.
The force F is applied by the press brake bending machine to drive the mutual movement between the upper and lower molds, thereby bending the plate. For bending 90° carbon steel plates, WILA gives the empirical value of the plate stress load, as shown in Table 1. When the thickness of the carbon steel is 20mm, the lower die with V=160mm can be selected. At this time, the force load of the bending machine is 150t/m.
F=force per unit length (t/m);
S= material thickness (mm);
ri= bending radius of inner corner (mm);
V= lower die opening size (mm);
B= shortest flange edge (mm) );
aluminum alloy: F×100%;
stainless steel: F×150%;
stamping and bending: F×(3~5)
The load-bearing methods of WILA heavy-duty upper hydraulic clamps include top load and shoulder load, and the maximum load is 250t/m and 800t/m respectively. The force-bearing surface of the fixture adopts CNC deep quenching hardening technology. The Rockwell hardness is 56~60HRC, and the hardening depth is up to 4mm, which has high hardness and strong wear resistance. The hydraulic clamp uses hydraulic rapid clamping, and the expansion of the hydraulic hose drives the movement of the clamping pin so that the mold is automatically seated and the bending line is automatically centered. For a bending mold with a total length of 6 meters, it only takes about 5 seconds for the hydraulic clamping to be fully clamped, and the comprehensive use efficiency is 3~6 times higher than that of the ordinary manual clamping system.