Die assembly technology
Die assembly technology is a comprehensive process for assembling qualified die parts into a complete mold according to design requirements. Its quality directly impacts the mold’s operating precision, service life, and the quality of the blanked parts. This technology encompasses multiple steps, including cleaning, positioning, securing, and adjusting parts. It requires adherence to strict assembly sequences and precision control requirements to ensure coordinated operation of all components. For complex dies, the assembly process also requires verification through trial molds, with dynamic adjustments optimizing assembly precision to meet mass production requirements.
Preliminary preparation for die assembly is crucial, including component inspection, cleaning, and matching. Part inspection requires checking key dimensions against the drawing, such as the punch and die edge dimensions, die parallelism, and the clearance between guide pins and guide bushings, to ensure all components meet quality standards. Cleaning removes oil, iron filings, and oxide layers from the component surfaces. Precision parts require ultrasonic cleaning to ensure the cleanliness of the assembly surfaces. Parts that require matching (such as the punch and retaining plate, and guide pins and die base) are grouped and matched to ensure the matching accuracy meets design requirements. For example, the clearance between guide pins and guide bushings must be controlled within a range of 0.01-0.03mm.
The assembly of the punch and die is the core of die assembly, and the key is to ensure uniformity of the cutting edge clearance. For simple dies, the punch and die can be fixed using a press-in method, and the clearance can be adjusted using shims: insert a copper sheet or paper of uniform thickness between the punch and die, tap the fixing plate to make the clearance uniform, and then tighten the fixing bolts. For complex dies, alignment is required using a process locator or jig boring machine, and a dial indicator is used to check the clearance at each point on the cutting edge, with the error controlled within 0.01-0.02mm. Multi-punch dies also require consistent height of each punch. This is achieved by grinding the upper surface of the punch fixing plate, with a height difference of no more than 0.01mm to avoid uneven force during stamping.
The assembly of the mold frame and auxiliary components must ensure overall rigidity and flexibility of movement. When assembling the mold frame, the guide pins and lower mold base, as well as the guide sleeves and upper mold base, are usually pressed in with an interference fit. After pressing in, the coaxiality of the guide pins and guide sleeves must be checked, and the error must not exceed 0.02mm/100mm. The assembly of positioning devices (such as stop pins and guide plates) must ensure the relative position accuracy of the positioning reference and the cutting edge. The height of the stop pins must be 0.5-1mm thicker than the sheet material, and the spacing between the guide plates must be 0.1-0.3mm wider than the sheet material. The assembly of the unloading device must ensure flexible movement, the spring compression of the elastic unloading device must be uniform, the fitting clearance between the unloading plate and the punch is 0.05-0.1mm, the rigid unloading plate must be parallel to the upper plane of the die, and the parallelism error must be ≤0.02mm/100mm.
The final step in die assembly is trial punching and adjustment, which verifies assembly quality through test punching. The same materials and equipment used in production are used during trial punching. A single-stroke test punch is performed first to check the cross-sectional quality, dimensional accuracy, and burr-free nature of the blanked part. Continuous-stroke test punching is then performed to observe smooth feeding and unloading, and any unusual die noises. If uneven clearances are detected, loosen the retaining bolts and readjust. If unloading is problematic, check the spring tension or the clearance of the unloading plate. If dimensions are out of tolerance, re-grind the cutting edge. After the trial punch passes, a life test of 500-1000 cycles is performed to ensure the die’s stability and reliability in mass production. Through scientific assembly techniques and rigorous trial punching adjustments, the die can achieve the designed precision and lifespan requirements.
