Stamping die is a special process equipment for processing materials into parts (or semi-finished products) in stamping processing.
Classification according to nature of process: punching die, bending die, drawing die, forming die, etc.
Classification according to degree of process combination: single process die, composite die, progressive die.

 

a) forming die b) deep drawing die c) flanging die d) bulging die
Three elements of stamping production: reasonable stamping process, advanced molds, and efficient stamping equipment.

 

Defects: excessive burrs, deformation, surface scratches, inconsistent dimensions, few holes, etc.
1) Excessive burrs: too large or too small gap between punch and die; cutting edge wear; poor guiding accuracy; position of punch and die is not concentric, etc.
2) Deformation: hole spacing is too small; binder plate is not well matched with concave model surface; gap is too large, etc.
3) Surface scratches: there are phenomena such as dragging and pulling during operation; sheet is scratched during shearing process, etc.
4) Size does not match: feeding is not in place; positioning device is damaged or loose, position is shifted, etc.
5) Few holes: punch is broken; length of punch is not enough, etc.

 

Blanking, punching, and trimming products are prone to defect positions

 

Drawn products are prone to defect locations

Defects: flanging is not vertical, flanging height is inconsistent, flanging is rough, flanging is cracked, etc.
1) Flanging is not vertical: gap between punch and die is too large.
2) Inconsistent flanging height: uneven gap between punch and die; inaccurate positioning; inaccurate size of blanking parts.
3) Flanging and napping: there are scars on cutting edge; there are impurities on the surface of part; hardness of cutting edge is too low.
4) Flange cracks: Burrs are large during trimming; gap between convex and concave dies is too small; shape of flange has a sudden change.

 

Flanged products are prone to defect positions

Defects: Bending angle is unqualified, bending edge is broken, and there is a step at bending R angle, etc.
1) Bending angle is unqualified: gap between punch and die is too large, matching angle of punch and die does not match thickness of plate material.
2) Bending edge is broken: gap between punch and die is too small; bending angle is too small; punching force is too large and speed is too fast; plate material is too hard.
3) There are steps in bending R angle: bending angle of convex and concave dies is too large; outer R angle is too large; bending force is too small.

 

Bending products are prone to defect positions

1) Length of punch is not enough, cut into die according to edge of punch and replace punch with a material thickness plus 1mm;
2) Die gap is too large, cut into die to reduce gap or use a coating machine to reduce gap;
3) Punch or mold plate is not demagnetized, and punch or mold plate is demagnetized with a demagnetizer.

1) Blanking hole is small or blanking hole is offset to increase blanking hole to make blanking smooth;
2) Blanking hole has a chamfer, and blanking hole is enlarged to remove chamfer;
3) There is no taper on knife edge, line cut taper or expansion hole on reverse side reduce length of straight wall;
4) Straight wall of knife edge is too long, and reverse side is drilled to shorten straight wall of knife edge;
5) Edge of cutting edge collapses, resulting in a large edge, and blocking material re-grinds cutting edge.

1) Cutting edge collapsed, causing cutting edge to be too large and regrinding cutting edge;
2) Gap between punch and die is too large, wire is cut into block, and gap is re-adjusted;
3) Smoothness of die edge is poor, and polished edge is straight;
4) Gap between punch and die is too small, save mold again, and match gap;
5) If ejecting force is too large, pull out cap in reverse to replace spring to reduce ejecting force.

1) Positioning offset adjustment positioning;
2) There is unilateral forming, material is pulled to increase pressing force, and positioning is adjusted;
3) Design is wrong, resulting in uneven knife connection and re-cutting edge inserts;
4) Feeding is not allowed to adjust feeder;
5) If calculation of feeding step distance is wrong, recalculate step distance and reset tool position.

1) Closing height is too low, and punch cuts into knife edge part too long to adjust closing height;
2) Improper positioning of material, causing punch to cut one side, adjust positioning or feeding device breaks due to uneven force;
3) The lower mold waste blocks knife edge, causing punch to break and re-drill large blanking hole to make blanking smooth;
4) Fixed part (splint) of punch and guide part are repaired or re-wired into block to make punch move up and down smoothly (plate) offset;
5) Poor guiding of punching plate, resulting in unilateral force on punch to re-repair punching plate gap;
6) Punch edge is too short, which interferes with beating plate and replaces punch to increase length of edge;
7) Punch is not fixed well, move up and down, re-fix punch so that it cannot move up and down;
8) Edge of punch is not sharp and regrinds edge;
9) Surface of punch is strained, force is uneven when material is removed, and punch is replaced again;
10) Punch is too thin, too long, and strength is not enough to change punch type;
11) Hardness of punch is too high, and material of punch is not correct. Replace material of punch and adjust hardness of heat treatment.

1) Recalculate position of bead or bending position if bead is dislocated;
2) Bending gap is too small, extrude iron filings to readjust gap, or grind forming block, or grind forming punch;
3) Bending punch is too sharp and R angle is repaired;
4) There is too little material to connect knife edge and reconnect knife edge;
5) Bead is too narrow and regrind bead.

1) Center of germination bottom hole does not coincide with center of germination punch to determine correct center position, or move position of germination punch, or move it to position of sprouting-side high-side low or even break dynamic pre-punching hole, or adjust positioning;
2) Gap between dies is uneven, resulting in germination-side height-edge repair, low gap or even rupture;
3) Germination bottom hole does not meet requirements, resulting in germination height and recalculation of bottom hole diameter, pre-punching hole increases or decreases diameter deviation, or even ruptures.

1) Punch of forming die is too sharp, which causes material to crack and R angle of forming punch is repaired, and R angle is properly repaired at knife edge;
2) Length of forming punch is not enough, resulting in failure to calculate correct length of forming punch and adjust actual length of punch to meet forming requirements;
3) Forming punch is too long, material at forming part is deformed, correct length of punch is even determined, and actual length of punch is adjusted to meet requirements until punch breaks;
4) Insufficient material at forming part causes cracking to calculate expanded material, or repair R angle, or reduce forming height;
5) Poor positioning, resulting in poor molding, adjust positioning or feeding device;
6) Forming gap is too small to cause cracking or deformation to adjust gap.

1) Mold is not adjusted in place, resulting in an angle error, resulting in a poor adjustment of closed height or a poor angle difference;
2) Insufficient elastic force causes poor angle and causes size deviation to replace spring;
3) Material does not meet requirements and angle is bad, which leads to changing material or readjusting gap deviation;
4) Material thickness deviation causes poor angle, resulting in size deviation to determine material thickness, change material or readjust gap difference;
5) Improper positioning leads to size deviation, adjust positioning to make size OK;
6) Design or processing errors cause gap repair welding and grinding between bending public pieces, eliminate gap between pieces, resulting in small bending size;
7) There is no R angle in forming process, bending height is too small under forming angle and other normal conditions;
8) Bending size on both sides is too large to add pressure ribs;
9) Dimensional instability caused by unilateral bending and pulling increases spring force and adjusts positioning;
10) Gap is unreasonable, causing poor angle and dimensional deviation to repair gap;
11) Height of folding knife is not enough, and bending punch is too short to fit into folding knife to increase height of folding knife, so that bending punch can be fitted into folding knife unit as much as possible, resulting in more bad angles;
12) Speed is too fast when bending, causing deformation at the root of bending. Adjust speed ratio control and choose a reasonable speed;
13) Structure is unreasonable, folding knife is not inserted into fixed mold plate, and groove is re-milled. When folding knife is inserted into mold plate for stamping, gap becomes larger;
14) Heat treatment hardness of forming male is not enough, resulting in collapse of pressing line or flattening of remanufactured male pressing line.

1) Improper positioning or improper feeding. Adjust positioning or feeding device;
2) Avoidance is not enough for grinding and avoiding;
3) Inner guide post is strained, resulting in poor board movement and replace inner guide post;
4) If punch is damaged or surface is not smooth, replace punch;
5) Position of ejector pin is unreasonable and position of ejector pin is re-arranged;
6) Ejecting force is not enough, or ejecting force is not enough to replace ejecting spring or ejecting spring;
7) Punch and splint are not matched smoothly; repair punch and splint to make punch fit smoothly;
8) Forming slider is not well matched, slider and guide groove are trimmed to make it fit smoothly;
9) Heat treatment of plate is uncomfortable, and after a period of stamping, it is deformed and plate is re-grinded to correct deformation;
10) Punch is too long or length of ejector pin is not enough to increase length of ejector pin or replace punch with a suitable length;
11) Punch is broken and punch is replaced;
12) Mold plate is not magnetically clouded, and workpiece goes up to bring mold plate to demagnetize.

1) Mold is not upright, resulting in tape and feeder and mold resetting mold or adjusting feeder are not on same straight line;
2) Adjust leveling machine or replace material if material belt is uneven;
3) If feeding is not smooth due to non-discharging, refer to solution of non-discharging;
4) Positioning is too tight to adjust positioning;
5) Pilot pin is too tight or straight wall is too long to adjust pilot pin;
6) Punch is not fixed well or is too long and interferes with material belt, punch with a suitable length is replaced and fixed again;
7) Ejector pin is too short, and material belt interferes with forming block. Adjust length of ejector pin to avoid interference;
8) Position of buoyant block is improperly arranged to adjust position of buoyant block.

1) Closed height of mold is improper, riveting is not in place, and closed height is adjusted;
2) Workpiece is not put in place, and positioning deviation is adjusted for positioning;
3) Before riveting, confirm sprouting hole if workpiece is defective, and refer to solution to defective sprouting hole to confirm whether riveting hole is chamfered. If there is no chamfering, add chamfering;
4) If length of riveting punch is not enough, replace it with a punch with a suitable length;
5) Confirm that riveting punch does not meet requirements and use a riveting punch that meets requirements.

1) Carefully make wrong punch when accidentally assembling;
2) Punch has no direction mark, and punch with direction is marked.

1) Don't know thickness of mold plate, knowing thickness of mold plate is too long or too short;
2) Insufficient care and experience in selecting appropriate screws.

1) Pin holes are not cleaned. Wipe pin holes and pins clean. When removing mold base, positioning pins should be removed first, and positioning pins are easy to be damaged.
2) Do not damage pin holes when mold assembly and disassembly procedures are incorrect and knock down pins.

1) When hole wall is roughened and scratched so that mold is too tight, carefully check whether pin hole is roughened, otherwise pin hole that cannot be punched out should be reamed;
2) Pin hole is offset or there is no escape hole below to add a positioning pin escape hole.

1) Did not pay attention to depth of spring hole to measure depth of spring hole, calculate compression amount of spring, re-select and cannot be pressed down;
2) Insufficient care and experience in proper spring bottom dead center.