I. Main components, functions, and safety requirements of the die.
The punch and die in the working area generally refer to the working parts that directly form the blank. They are key components of the die. The punch and die are not only precise and complex but also need to meet the following requirements:
(1) The punch and die should have sufficient strength and will not crack or break during stamping.
(2) The material and heat treatment should have appropriate requirements to prevent brittle cracking caused by excessive hardness.
1. Positioning parts: Positioning parts determine the installation position of the blank, including locating pins (plates), stop pins (plates), pilot pins, stock guides, side cutters, side pressure plates, etc. When designing positioning parts, ease of operation should be considered, and there should be no over-positioning and the position should be easy to observe. It is best to use front push positioning, outer contour positioning, pilot pin positioning, etc.
2. Blank holder, stripper, and ejector: Blank holder, stripper plate, etc.
The blank holder can apply blank holder force to the drawing blank, effectively preventing the blank from arching and wrinkling under tangential pressure. The blank holder plate is used to prevent the blank from moving and rebounding. The stripper and stripper plate are used to facilitate stripping and cleaning of scrap. Their supporting devices are springs, rubber, and air cushion push rods, which can move up and down. The ejector must have sufficient ejection force and its action must have a certain limit. The stripping device should be processed to the working position as much as possible in enclosed areas or milled slots. The exposed stripper plate should have protective plates around it to prevent fingers from reaching in and foreign objects from entering, and the exposed surfaces should be chamfered.
3. Guide components: Guide pillars and guide bushings are one of the most widely used guide components. Their function is to ensure precise clearance between the punch and die during punching. Therefore, the clearance between the guide pillar and guide bushing should be smaller than the die clearance. The guide pillar is set at the lower die position to ensure that the upper end of the guide pillar is at least 5-10 mm above the top of the upper die plate. The guide pillar should be located away from the die block and blank holder plate so that the operator's arm does not need to pass through the guide pillar to feed the material.
4. Support and clamping parts: These include the upper and lower die plates, die sets, punch and die retainers, backing plates, limiters, etc. The upper and lower die plates are the basic components of the stamping die, and other components are individually installed and fixed. The plane dimensions of the die plate, especially the front and rear directions, should meet the requirements; too large or too small is not conducive to use.
Some dies (blanking, punching, etc.) need to install backing plates under the die set to facilitate the production of parts. In this case, it is best to connect the backing plate and the die plate with screws, and the thickness of the two backing plates should be absolutely equal. The spacing between the backing plates should be based on the capacity of the parts. Do not make it too large to avoid damaging the die plate.
5. Fasteners include screws, nuts, springs, dowel pins, washers, etc., and standard parts are typically used. Stamping dies contain a large number of standard parts. During design and selection, ensure that fasteners and elastic components are pushed out to avoid exposing fasteners on the surface at operational positions, preventing contact and obstruction during operation.
II. Safety Key Points in Die Design
In terms of structure, feeding, positioning, discharging, and scrap removal should be facilitated as much as possible. When processing small parts, operators' fingers, wrists, or other body parts must be prohibited from entering the die. For large part processing, when operators must handle the die, the die's range should be minimized, the dwell time of body parts within the die should be shortened as much as possible, the hazardous area of the die should be clearly defined, and necessary protective measures and equipment should be provided.
During use, all components of the die should have sufficient strength and rigidity to prevent damage or deformation. Fasteners should incorporate anti-loosening measures to avoid accidental injury to operators.
During processing, there should be no phenomena such as scrap or workpiece ejection that could distract operators or even cause injury. Additionally, to avoid burrs on stamped parts cutting hands, operators should not have excessive movement ranges when operating the press, to prevent losing a stable body position. During work, there should not be too many or overly difficult movements. During handling, strong noise and vibration should be avoided as much as possible. The die frame design should indicate the die weight on the general assembly drawing to facilitate installation and ensure safety. Parts weighing over 20 kg should have loading and unloading measures to reduce labor intensity. Die loading and unloading components should be convenient and safe, avoiding potential hand pinching or cutting. The die should be easy to disassemble and reassemble. In summary, even very minor die issues can affect die safety; only by analyzing the specific problems of each task can safety precautions in die design be proposed.
The above content related to stamping die design involves multiple aspects, not only meeting customer processing requirements but also considering performance and processing characteristics. Of course, safety is also an important factor that cannot be ignored. I hope the above content is helpful to readers.