Bending process criterion

Preparation before bending

Check the length, width, and thickness of the material. The plate should be cleaned and the surrounding area should be deburred.

Check the condition of the press brake machine and perform necessary cleaning and maintenance.

Compare the workpiece with the drawing, and check the shape of the workpiece, the processing size, the thickness of the material, the processing technology requirements and the drawing projection method.

Selection of bending die

The lower bending mould is generally determined according to the thickness of the workpiece, and the bending groove is usually selected at 8 times of the thickness of the bending plate. Note: When bending at 90°, the minimum width of the "V" groove should not be less than 4t, otherwise it may damage the mould or cause the workpiece to be scrapped; if the hemming size is too small, a "V" groove below 4t must be used. After the obtuse angle is suitable, use a large "V" groove to fold it to 90°.

In addition to considering the thickness of the plate, the upper punch die of hydraulic press brake must also consider the avoidance problem. For deep U-shaped products, a customized gooseneck dies must be used,check following Figure 1, For other special shapes which require avoidance, the corresponding avoidance mould should also be selected

          Figure1: Gooseneck tooling                                                Figure2: Special dies

First piece bending

According to the drawings, refer to the above process requirements, program and process; conduct the first article inspection. If the drawings have tolerance requirements, they shall be inspected strictly according to the drawings. If there are no requirements on the drawings, they shall be inspected according to the following standards (see Inspection). Processing can only be carried out after the first piece has passed the inspection. The blanks and workpieces should be stored on the pallet to avoid scratches. For the first piece thatcannot be formed at one time, the operator and inspector should calculate whether the remaining unfolded size can meet the formed size. tolerance.

Batch bending

After the first piece of bending has passed the inspection, save the programs and procedures, set the required quantity, and hand it over to ordinary workers to complete this batch of job.

Process control

Surface quality control: After the workpiece is formed, there should be no obvious defects such as indentation and die mark;

For oxidized parts, electrolytic parts, aluminum-zinc-coated plates, etc., a special protective film must be placed between the lower "V" tank and the workpiece; the workpiece must not be dragged, pulled or pulled at will to avoid scratches;

Matters need attention

• Pressbrake must be shut down when replace the moulds and dies, and the machine must be shut down when leaving the equipment. The two people must coordinate their work.During the bending process, they must be sharp-eyed, the man-machine cooperation is consistent, and the energy must be concentrated. Personnel irrelevant to the operation must not stand near the machine tool.

• When loading the material, the hand should use the correct method to hold the workpiece: the thumb is above the material, and the remaining four fingers are below the material. For processing smaller workpieces, use pliers instead of hands to clamp the workpiece.

• When bending a long work piece, do not extend the head, chest, etc. into the work piece to prevent the work piece from bouncing off and hurting the body;

• When bending thicker sheets above 2.5mm and wider and longer workpieces, the bending speed should not be too fast, and the upper die and lower moulds must be slowly matched to avoid mold damage and personal safety.

• For thinner and smaller workpieces, the speed should also be slow to avoid inconsistent man-machine coordination and deformation of the workpiece; when the dead edge is pressed, the minimum angle should not be less than 40°.

• When the sample is processed, the waste material must be used for trial folding to meet the requirements of the drawing before it can be formed, and the process problems that have an impact on this processing should be recorded and reported to the relevant project engineer.

• When the bending machine is working, it is strictly forbidden to extend the hand from the bottom of the mold into the back of the machine tool on the front of the machine tool after adjusting the positioning gauge and repairing the machine tool.