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What is Hydraulic Press Brake?

DA58T CNC PRESS BRAKE

Hydraulic Press Brake is a machine capable of bending thin plates. Its structure mainly 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 composed of a seat shell, a coil and a cover plate. The coil is placed in a recess of the seat shell, and 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 realizing the clamping of the thin plate between the pressure plate and the base. Due to the use of electromagnetic force clamping, the pressing plate can be made into a variety of workpiece requirements, and the workpiece with side walls can be processed, and the operation is also very simple.

1. working principle

Hydraulic Press Brake

Hydraulic Press Brake includes a bracket, a worktable and a clamping plate. The worktable is placed on the bracket. The worktable consists of a base and a pressure plate. The base is connected to the clamping plate by 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 realizing the clamping of the thin plate between the pressure plate and the base. Due to the use of electromagnetic force clamping, the pressing 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.

2. Main categories

Hydraulic Press Brake is divided into manual press brakes, Hydraulic Press Brake and CNC Press Brake. Manual press brakes are divided into mechanical manual press brakes and electric manual press brakes. Hydraulic Press Brake can be divided into torsion shaft synchronization, machine-hydraulic synchronization, and electro-hydraulic synchronization according to the synchronization mode. Hydraulic Press Brake can be divided into upper movement type and lower movement type according to the movement mode.

3. Structure description

Hydraulic Press Brake is an important equipment for bending and forming workpieces in the sheet metal industry. Its role is to press steel plates into parts of various shapes according to the process requirements. As shown in the figure, it is a schematic diagram of the structure of a hydraulic sheet metal bending machine. The frame is mainly composed of left and right uprights, worktables, and beams. The left and right oil cylinders are fixed on the uprights. Movement, the lower mold is fixed on the worktable, the upper mold is installed at the lower end of the slider, the hydraulic system provides power, and the electrical system gives instructions. Under the action of the oil cylinder, the slider drives the upper mold down and the lower mold to close to achieve the folding of the sheet bend. The left and right columns, working table and slider (hereinafter referred to as the three major parts) are the key parts of the bending machine, and the total weight of the three major parts accounts for 70% to 80% of the total weight of a bending machine. Its strength and rigidity directly determine the running accuracy, service life of the machine tool, and the accuracy of the workpiece.

  1. Slider part: adopts hydraulic transmission, and the slider part is composed of the slider, oil cylinder and mechanical stopper fine-tuning structure. The left and right oil cylinders are fixed on the frame, and the piston (rod) is driven by the hydraulic pressure to move the slider up and down, 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. The minimum reading is 0.01 mm (there is a limit switch limit for the front and rear positions)
  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. The numerical control system controls the material blocking size.

4. Structural features

  1. All-steel welding structure is adopted, which has sufficient strength and rigidity;
  2. Hydraulic upper transmission, the oil cylinders at both ends of the machine tool are placed on the slider to directly drive the sliding work;
  3. The slider synchronization mechanism adopts torsion shaft to force synchronization;
  4. Adopt mechanical stop structure, stable and reliable;
  5. The slider stroke can be adjusted quickly and manually, with manual fine adjustment and counter display;
  6. Oblique wedge type deflection compensation mechanism to ensure high bending accuracy.

5. How to use Hydraulic Press Brake

Processed by ordinary Hydraulic Press Brake

Q235 sheet for a brief introduction:

  1. Turn on the power first, turn on the key switch on the control panel, and then press the oil pump to start.
  2. Stroke adjustment, the use of bending machine must pay attention to adjust the stroke, must be tested before bending. When the upper die of the bending machine descends to the bottom, there must be a gap of plate thickness. Otherwise it will cause damage to the mold and machine. The adjustment of the stroke also has electric quick adjustment and manual fine adjustment.
  3. For the selection of bending notches, generally choose notches with 8 times the width of the plate thickness. For bending a 4mm sheet, a notch of around 32 is required.
  4. The back gauge adjustment generally has electric quick adjustment and manual fine adjustment, the method is the same as the shearing machine.
  5. Press the foot switch to start bending. The bending machine is different from the shearing machine. It can be released at any time. When the foot bending machine is released, it will stop and then step on to continue down.

6. Care and maintenance

Before the maintenance or wiping of the machine tool, the upper mold should be aligned with the lower mold and then put down and shut down until the work is completed. If you need to start up or other operations, you should select the mode to manual and ensure safety. The maintenance contents are as follows:

  1. Hydraulic oil circuit
    1) Check the oil level of the oil tank every week. If the hydraulic system is repaired, it should be checked. If the oil level is lower than the oil window, hydraulic oil should be added;
    2) The hydraulic oil used in this machine is ISO HM46 or MOBIL DTE25;
    3) The new machine should be changed after 2000 hours of operation. After every 4000-6000 hours of operation, the oil should be changed. Every time the oil is changed, the oil tank should be cleaned;
    4) The system oil temperature should be between 35 ° C and 60 ° C, and should not exceed 70 ° C. If the temperature is too high, the oil quality and accessories will be damaged.
  2. Filter
    1) Each time the oil is changed, the filter should be replaced or thoroughly cleaned;
    2) The machine tool has related alarms or the oil quality is not clean and other filters are abnormal, which should be replaced;
    3) The air filter on the fuel tank is inspected and cleaned every 3 months, and it is best to replace it every year.
  3. Hydraulic components
    1) Clean the hydraulic components (substrates, valves, motors, pumps, oil pipes, etc.) monthly to prevent dirt from entering the system and cannot use cleaning agents;
    2) After the new machine is used for one month, check the bends of the oil pipes for deformation. If there is any abnormality, it should be replaced. After two months of use, the joints of all accessories should be fastened. pressure.

7. Proper purchase Hydraulic Press Brake

Once the selection of the bending machine is inappropriate, the production cost will rise, and the bending machine cannot be expected to recover the cost. Therefore, there are several factors that must be weighed in the decision.

Artifact

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. Part length is very important to determine the specifications of the new machine.

Torsion

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 machine’s tonnage table from the bending machine manufacturer. The table shows the estimated tonnage required per foot length under different thicknesses and different materials.

Bending radius

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 m) opening distance to form 16 gauge mild steel, the bending radius of the part is about 0.078 inch. If the bending radius is almost as small as the thickness of the material, the bottomed die must be formed. However, the pressure required to form the bottomed die is about 4 times greater than free bending.

If the bending radius is less 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 bent excessively about 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 bottomed concave mold bending, the mold angle is generally 86 ~ 90 °. At the bottom of the stroke, there should be a gap between the male and female dies slightly larger than the thickness of the material. The forming angle is improved, because the tonnage of the bottomed die bending is larger (about 4 times of free bending), which reduces the stress that usually causes springback within the bending radius.

The embossing bending is the same as that 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.

Curvature

Bending accuracy requirements are a factor that needs to be carefully considered. It is this factor that determines whether a CNC press brake or a manual bending machine needs to be considered. If the bending accuracy requires ± 1 ° and it cannot be changed, you must focus on the CNC machine.

CNC press brake The repeatability of the slider 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 a suitable 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.

Mould

Even if there are racks full of molds, do not think that these molds are suitable for the newly bought 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.

Bending piece side length

Suppose you bend 90 ° along a 5-gauge 10-gauge low-carbon steel plate. The bending machine must probably apply an additional 7.5 tons of pressure to push the steel plate up, and the operator must be prepared for the 280 pound straight edge to fall . Manufacturing this part may require several strong workers or even a crane. Bending machine operators often need to bend long-edge parts without realizing how strenuous their work is.

8. Safe operating procedures

  1. Strictly abide by the safety operation rules of machine tool workers, and wear labor protection articles as required;
  2. Before starting, you must carefully check whether the motor, switch, line and ground are normal and firm, and check that the operating parts and buttons of the device are in the correct position;
  3. Check the coincidence and firmness of the upper and lower molds; check whether each positioning device meets the requirements of being processed;
  4. When the upper slide and each positioning axis are not at the origin, run the origin return procedure;
  5. After the equipment is started, it will run for 1 ~ 2 minutes and move on the skateboard full stroke for 2 ~ 3 times. If it finds abnormal sound or failure, it should stop immediately and eliminate the failure.
  6. When working, one person should direct the operation to make the operator closely cooperate with the feeding and suppressing personnel to ensure that the cooperating personnel are all in a safe position to send the bending signal
  7. The sheet must be compacted during bending to prevent the sheet from lifting and hurting people during bending;
  8. The power must be cut off when adjusting the plate material and pressing the mold, and the operation should be carried out after stopping the operation;
  9. When changing the opening of the variable lower die, no material is allowed to contact the lower die;
  10. When the machine tool is working, no one is allowed to stand behind the machine tool;
  11. It is strictly forbidden to fold the sheet material at one end alone;
  12. When the workpiece or mold is found to be incorrect during operation, it should be stopped and corrected. It is strictly prohibited to correct by hand during operation to prevent injury to the hand;
  13. It is forbidden to fold ultra-thick iron plates or quenched steel plates, high-grade alloy steels, square steels and sheets that exceed the performance of sheet metal bending machines to avoid damage to the machine tool
  14. Regularly check the coincidence of the upper and lower molds; whether the indication of the pressure gauge meets the regulations;
  15. Shut down immediately when an abnormality occurs, check the cause and eliminate it in time;
  16. Before shutting down, place wooden blocks on the lower molds under the cylinders on both sides to lower the upper slide onto the wooden blocks;
  17. Exit the control system program first, then cut off the power.

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