Views: 160 Author: Site Editor Publish Time: 2020-07-09 Origin: Site
According to the synchronization mode, hydraulic bending machine can be divided into: torsion shaft synchronization, machine-hydraulic synchronization, and electro-hydraulic synchronization. According to the movement mode, it can be divided into: upward movement type and downward movement type.
The bending machine includes a bracket, a worktable and a clamping plate. The worktable is placed on the bracket. The worktable is composed of a base and a pressing plate. The base is connected to the clamping plate through a hinge. The base is composed of a seat shell, a coil and a cover plate. In the recess of the seat shell, the top of the recess is covered with a cover plate.
When in use, the coil is energized by a wire, and after being energized, a gravitational force is generated to the pressure plate, thereby achieving clamping of the thin plate between the pressure plate and the base. Due to the use of electromagnetic force clamping, the pressure plate can be made into a variety of workpiece requirements, and the workpiece with side walls can be processed. The bending machine can change the bending machine mold to meet the needs of various workpieces!
The bending machine is divided into manual bending machine, hydraulic bending machine and CNC bending machine. Manual press brakes are divided into mechanical manual press brakes and electric manual press brakes. Hydraulic press brakes can be divided into torsion shaft synchronization, machine-hydraulic synchronization, and electro-hydraulic synchronization according to the synchronization mode. The hydraulic bending machine can be divided into upper movement type and lower movement type according to the movement mode.
1. Slider part: It adopts hydraulic transmission, and the slider part is composed of slider, oil cylinder and mechanical stopper fine-tuning structure. The left and right oil cylinders are fixed on the frame, and the piston (rod) drives the slider to move up and down through hydraulic pressure, and the mechanical stop is controlled by the numerical control system to adjust the value;
2. Part of the working table: it is operated by the button box, which causes the motor to drive the stopper to move forward and backward, and the moving distance is controlled by the numerical control system. Its minimum reading is 0.01 mm (both front and rear positions have limit of travel switch);
3. Synchronization system: This machine is a mechanical synchronization mechanism composed of torsion shaft, swing arm, joint bearing, etc. It has simple structure, stable and reliable performance, and high synchronization accuracy. The mechanical stop is adjusted by the motor, and the numerical control system controls the value;
4. Material blocking mechanism: the material blocking is driven by a motor, and the two screw rods are driven to move synchronously through the chain operation, and the numerical control system controls the material blocking size.
Once the selection of the bending machine is inappropriate, the production cost will rise, and the bending machine can not be expected to recover the cost. Therefore, there are several factors that must be weighed in the decision.
The first important thing worth considering is the parts you want to produce. The point is to buy a machine that can complete the processing task with the shortest work table and the smallest tonnage.
Carefully consider the material grade and maximum processing thickness and length. If most of the work is low carbon steel with a thickness of 16 gauge and a maximum length of 10 feet (3.048 meters), the free bending force need not be greater than 50 tons. However, if you are engaged in a large number of bottomed die forming, perhaps a 160-ton machine tool should be considered.
Assuming that the thickest material is 1/4 inch, 200 tons of free bending at 10 feet is required, and at least 600 tons for bottomed die bending (corrected bending). If most of the work pieces are 5 feet or shorter, the tonnage is almost halved, which greatly reduces the purchase cost. The length of the parts is very important to determine the specifications of the new machine.
Under the same load, the deflection of the 10-foot machine table and slider is four times that of the 5-foot machine. This means that shorter machines require fewer shim adjustments to produce qualified parts. Reducing shim adjustments also shortens preparation time.
Material grade is also a key factor. Compared with low carbon steel, the load required for stainless steel is usually increased by about 50%, while most brands of soft aluminum are reduced by about 50%. You can always obtain the tonnage table of the machine from the bending machine manufacturer. The table shows the estimated tonnage required per foot length under different thicknesses and different materials.
When using free bending, the bending radius is 0.156 times the opening distance of the die. In the free bending process, the opening distance of the die should be 8 times the thickness of the metal material. For example, when using a 1/2 inch (0.0127 meter) opening pitch to form 16 gauge mild steel, the part's bending radius is about 0.078 inch. If the bending radius is as small as the material thickness,
Bottom die forming is required. However, the pressure required to form the bottomed die is about 4 times greater than free bending.
If the bending radius is smaller than the thickness of the material, a punch with a radius at the front end smaller than the thickness of the material must be used, and resort to the imprint bending method. In this way, 10 times the pressure of free bending is required.
As far as free bending is concerned, the punch and die are processed at 85° or less (smaller is better). When using this set of molds, pay attention to the gap between the punch and the die at the bottom of the stroke, and enough to compensate for the springback and keep the material from bending excessively around 90°.
Generally, the springback angle of a free bending die on a new bending machine is ≤2°, and the bending radius is equal to 0.156 times the opening distance of the die.
For bending of bottomed concave molds, the mold angle is generally 86 ~ 90°. At the bottom of the stroke, there should be a gap between the male and female molds slightly larger than the thickness of the material. The forming angle is improved because the tonnage of the bottomed die is larger (about 4 times that of free bending), which reduces the stress that usually causes springback within the bending radius.
The embossing bending is the same as the bending of the bottomed concave mold, except that the front end of the punch is processed to the required bending radius, and the gap between the convex and concave molds at the bottom of the stroke is less than the material thickness. Due to the application of sufficient pressure (about 10 times of free bending) to force the front end of the punch to contact the material, springback is basically avoided.
In order to select the lowest tonnage specification, it is best to plan for a bending radius greater than the thickness of the material, and use the free bending method as much as possible. When the bending radius is large, it often does not affect the quality of the finished part and its future use.
The bending accuracy requirement is a factor that needs to be carefully considered. It is this factor that determines whether a CNC bending machine or a manual bending machine needs to be considered. If the bending accuracy requires ±1° and cannot be changed, it is necessary to focus on the CNC machine.
The repeatability of the slider of the CNC bending machine is ±0.0004 inches, and the precise angle of forming must adopt such precision and good mold. The repeatability of the slider of the manual bending machine is ±0.002 inches, and the deviation of ±2~3° will generally occur under the condition of using the appropriate mold. In addition, the CNC bending machine is ready for rapid mold loading, which is an undoubted reason to consider when it is necessary to bend many small batch parts.
Even if there are racks full of molds, do not assume that these molds are suitable for the newly purchased machine. The wear of each mold must be checked by measuring the length from the front end of the punch to the shoulder and the length between the shoulder of the die.
For conventional molds, the deviation per foot should be around ±0.001 inches, and the total length deviation should not be greater than ±0.005 inches. As for the precision grinding mold, the accuracy per foot should be ±0.0004 inches, and the total accuracy should not be greater than ±0.002 inches. It is best to use fine grinding dies for CNC bending machines and conventional dies for manual bending machines.
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