Heavy plate bending parts widely use in various fields, such as construction machinery and rolling stock such as bulldozers, excavators, loaders, and railway passenger cars. Generally speaking, the medium-thickness plate refers to the metal plate whose thickness is between 4.5~25mm.
At present, the forming methods of medium and heavy plates mainly include bending forming by bending machine, rolling forming by plate bending machine, and forming by press mold. Among them, bending forming is a forming method with a wider range of applications and a richer product line for medium and thick plates.
The difficulty in bending medium and thick plates is that the workpiece is long, the pressure is large, the forming is difficult, the efficiency is low, and the accuracy is difficult to control. 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.
This article will introduce in detail the efficient solution of WILA in the bending process of medium and heavy plates from several aspects such as heavy upper hydraulic clamps, heavy mechanical compensation tables, heavy bending dies and high-efficiency die stations related to the bending of medium and heavy plates program.
The first problem facing medium and heavy plate bending is the tonnage selection of the bending machine, and whether the load-bearing capacity of fixtures and molds meets the requirements. Figure 1 is a schematic diagram of conventional bending forming.
The bending machine exerts a force F to drive the mutual movement between the upper and lower dies, so as to perform the bending of the plate. For bending 90° carbon steel plates, WILA gives the empirical value of the plate stress load, as shown in the figure below. 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);
R=Bend radius of inner corner (mm);
V=Lower mold opening size (mm);
B=The shortest flange edge (mm);
Aluminum: F×50%; Aluminum alloy: F×100%; Stainless steel: F×150%;
Stamping and bending: F×(3~5)
Heavy-Duty Upper Hydraulic Clamp
For the bending of medium and heavy plates, WILA’s new-level version of the heavy-duty upper hydraulic clamp can easily handle it, the model is NSCL-HD-II-HC/UPB, and its appearance and dimensions are shown in the figure.
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. According to the tonnage table of medium and heavy plate bending, this heavy-duty clamp can fully meet the tonnage requirements for bending medium and heavy plates. The force-bearing surface of the fixture adopts CNC deep quenching hardening technology.
The Rockwell hardness is 56~60HRC, and the hardening depth is as high as 4mm, which has high hardness and strong wear resistance. The surface accuracy of this heavy-duty upper hydraulic clamp can reach ±0.01mm, and it can achieve accurate bending even when bending medium and thick plates. The hydraulic pressure is used for rapid clamping, and the movement of the clamping pin is driven by the expansion of the hydraulic hose 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. The schematic diagram of the hydraulic clamp is shown in the figure.
Heavy Machinery Compensation Workbench
For the bending of medium and thick plates, WILA’s new-level version of the heavy-duty mechanical compensation table can not only easily meet the load-bearing requirements, but also compensate for the deflection and deformation of the bending machine. Its model is NSCR-HD-II-HC-150/250- CNC/UPB, the appearance and dimensions are shown in the figure.
WILA’s heavy-duty upper hydraulic clamp has only the shoulder load, and its maximum shoulder load is 800t/m, which is completely suitable for heavy load applications in the bending of medium and thick plates. Even for heavy-duty bending of medium and thick plates, WILA mechanical compensation curves are still designed according to the parameters of the bending machine one-to-one to compensate for the entire deflection and deformation of the bending machine, and it is unique.
The mechanical compensation workbench adopts hydraulic clamping, the surface accuracy can reach ±0.01mm, the Rockwell hardness is 56~60HRC, and the hardening depth is up to 4mm. The mechanical compensation workbench adopts the universal UPB installation interface of WILA, which is easy to install and has higher accuracy. It also has its own Tx and Ty direction adjustments, which can ensure that the workbench and the backgauge remain parallel in the front and rear directions, and local angle deviations can be performed Correction.
Due to the thickness of the plate, the lower mold with a larger opening size (V24~V300) and the mold with a larger bearing capacity are generally selected for the bending of medium and thick plates. The overall dimensions of the mold are generally large, and the weight of the mold has exceeded the normal handling capacity of the operator.
With the help of roller bearings, WILA’s patented technology E2M (Easy to Move) allows operators to move heavy bending molds conveniently, safely, and quickly, greatly saving mold replacement and machine adjustment time.
WILA can provide bending molds with various knife shapes and lower mold openings to meet customer needs, such as straight knives, gooseneck scimitars, fillet molds, and Multi-V molds. Through precise grinding of key parts, the dimensional accuracy of the mold is as high as ±0.01mm.
Through the processing of CNC deep quenching and hardening technology, the hardness of the mold can reach 56~60HRC, and the depth of the hardened layer can reach 4mm. Strict tolerance requirements and hardening treatment ensure ultra-high-precision precision bending and ultra-long service life. The commonly used heavy-duty molds are shown in the figure. BIU-038 can carry up to 225t/m and can be equipped with E2M function; OZU-HD-376 can carry up to 350t/m and can be equipped with E2M function.
For the bending of medium and thick plates with different plate thicknesses, WILA also provides Multi-V molds, which are available in two forms: automatic adjustable V port and manual adjustable V port, as shown in the figure. The V opening size of the lower mold can be arbitrarily adjusted according to the characteristics of the plate through the numerical control motor or the adjustment block, which is especially suitable for bending medium and thick plates with high resilience and high strength.
At the same time, the Multi-V mold comes with hardened rollers with a low friction coefficient, which can greatly reduce the external creases of the bending parts, and at the same time, it can reduce the bending by 10%~30% compared with the traditional lower mold force.
Efficient Mold Station
The specially designed high-efficiency mold station of the bending machine can safely store heavy bending molds. At the same time, it is equipped with the corresponding E2M roller bearing system, which can change the upper and lower molds more quickly and efficiently.
The high-efficiency mold station is composed of two parts: the mold station and the carrying arm. The carrying arm can move back and forth along the mold station. All heavy molds can be easily slid from the mold station to the carrying arm, and then installed on the bending machine, which can ensure that the mold is from storage to Safety and convenience in use.
High-Efficiency Solution For Medium And Heavy Plate Bending
The picture below shows WILA’s complete and efficient solution for medium and heavy plate bending, which is mainly composed of heavy-duty upper hydraulic fixtures for bending machines, heavy-duty mechanical compensation tables, heavy-duty bending molds, and high-efficiency mold stations. The detailed functions of each component are as follows.
A: The large gooseneck scimitar of the new height version has an additional rolling bearing, which can change the mold more safely and conveniently.
B: Heavy-duty molds (with E2M), with the help of roller bearings, allow operators to move the heavy-duty molds conveniently, safely, and quickly, which greatly saves the time for mold change and machine adjustment.
C: E2M protective end cap. This end cap has a locking structure to ensure that when the clamp is loosened and the safety button of the mold is not pressed, the mold will not slip out of the left and right sides of the clamp.
D: The heavy-duty upper hydraulic clamp NSCL-HD-II-HC/UPB adopts the universal UPB installation form to install and clamp the mold safely and quickly.
E: The heavy-duty upper hydraulic clamp can be used with all of WILA’s new-level upper molds.
F: Efficient mold station, which can safely store and replace heavy bending molds.
G: Pillars can be used to support a wider and heavier lower mold, thereby increasing the stability of the mold during the bending process.
H: The Tx adjustment function of the mechanical compensation table can make the bending center line and the back gauge achieve a higher degree of parallelism.
J: The heavy-duty machinery compensation workbench NSCR-HD-II-HC-CNCE2M-250/UPB adopts the universal UPB installation form, which can be installed and adjusted safely and quickly. It can be matched with all the lower molds of WILA’s new standard height configuration.
K: The protective end cover of the mechanical compensation worktable prevents the mold from colliding with the fixture when the mold is loaded in the horizontal direction.
L: WILA’s patented technology E2M, with a roller bearing at the bottom of the mold, allows operators to move heavy molds conveniently, safely and quickly.