How to calculate the maintenance rate of stamping die

What are the common repair methods of 16 blanking die?

The repair process of commonly used words in blanking die is as follows:

(1) One method of grinding dull convex and concave dies is grinding with oilstone kerosene or pneumatic grinding wheel, and the other method is grinding with surface grinder.

(2) When repairing the convex-concave die with large gap, first check the gap with a block gauge of appropriate size. If the gap is not big, just sharpen the plane of the cutting edge and then trim it with an oilstone. If the gap is too large, oxygen-acetylene gas welding can be used for heating and local forging. For stamping dies, the periphery of the edge of the female die should be struck to ensure the size of the male die; for blanking dies, the male die should be struck to ensure the size of the female die. After the striking extension size is consistent, the striking can be stopped.

(3) When grinding a convex-concave die with uneven clearance, there are two situations besides natural wear:

1) The cylindrical pin is loose and loses its positioning ability, resulting in dislocation of the punch and the die and uneven clearance. The alignment of the cutting edges of the punch and the die should be restored evenly, and then the original pin hole should be hinged with 0. 1~0.2mm, and then used as a non-standard cylindrical pin.

2) The guide device is worn, the accuracy is reduced, and it can't play a guiding role, which makes the punch and die relatively offset. It is necessary to chrome-plate the surface of the guide post, and then polish it with the guide sleeve until the original fit clearance and accuracy level are restored.

(4) Replace the micro punching and blanking punch.

According to the defects of blanking parts, through quality analysis, find out the causes of defects, and finally eliminate the influence through repair and adjustment, as shown in the following table:

serial number

Quality problem

cause analysis

solution

The product section is bright and wide, with serrated burrs.

The blanking gap is too small.

Reduce the punch of blanking die or increase the concave die of blanking die to ensure a reasonable gap.

The product has rough cross section, large fillet, small bright band and elongated burr.

The blanking gap is too large.

Replace or repair the punch of the blanking die or the female die of the punching die, and ensure a reasonable gap.

three

The bright band of the product section is uneven or there is a burr with an inclined plane on one side.

Uneven blanking gap

Repair the punch or die and adjust the gap evenly.

four

After blanking, the parts are bent.

The concave die has an inverted cone or the top plate has a small contact surface with the workpiece.

Repair the concave die and adjust the top plate

five

After correction, the workpiece size is out of tolerance.

After blanking, the workpiece bends, which is common in blanking dies.

Reduce the female die of the blanking die or replace the blanking die with the ejector.

six

The inner hole deviates from the outer position.

1. The position of the plug tip is incorrect.

2. The guide pin is too small

3. Side distance is not allowed.

1. Correct the position of the plug tip.

2. Replace the guide pin

Corrected side

seven

Orifice rupture or part deformation

1. The guide pin is larger than the hole.

2. Positioning the guide pin is not allowed.

1. Calibration guide pin

2. Correct positioning errors

eight

Workpiece deformation

1. is caused by internal stress of the material.

2. The force is uneven when ejecting the parts.

1. Change the layout or normalize the material.

2. Adjust the mold to make the top plate work normally.

nine

bite

1. The gap between the guide post and the guide sleeve is too large.

2. The hole on the push block is not vertical, which makes the small punch offset.

3. The punch or guide post is not installed vertically.

4. Parallelism error accumulation

1. Repair or replace the guide post guide sleeve.

2. Repair or replace the push block

3. Reassemble to ensure verticality.

4. Re-grinding and assembly

Abnormal peeling

1. The stripper is too tightly matched with the punch, the stripper is tilted or other stripper parts are improperly installed.

2. Spring or rubber is not elastic enough

3. The punching hole of the female die is not aligned with the discharging hole of the lower die holder.

4. The female die has an inverted cone.

1. Trimming and stripping.

2. Replace the spring or rubber

Step 3 repair the leaking hole

4. Trim the concave die

18 how to analyze the trimming die according to the quality of bending parts?

The causes and adjustment methods of bending defects are as follows:

serial number

Quality problem

cause analysis

solution

The height and size of the parts are unstable.

1. The height dimension is too small.

2. The concave die fillet is asymmetrical.

1. The height dimension cannot be less than the minimum limit dimension.

2. Correct the fillet of concave die

There is a crack in the bending angle.

1. The bending inner radius is too small.

2. The grain direction of the material is parallel to the bending line.

3. The burr of the blank faces outward.

4. Metal plasticity is poor

1. Increase the bending radius of the punch

2. Change the blanking layout

3. Burrs in parts are changed to rounded corners.

4. Annealing or using soft materials

three

The outer surface of the workpiece is serrated.

1. The fillet radius of the concave die is too small.

2. The concave surface is rough and the gap is small.

1. Increase the fillet radius of the mold.

2. Correct the gap between male and female dies.

four

Extrusion thinning of curved surface

1. The fillet of the concave die is too small.

2. The gap between male and female dies is too small.

1. Increase the fillet radius of the mold.

2. Correct the gap between male and female dies.

five

The bottom of the concave part is uneven.

There is no ejector in the female die.

Add injector or calibration.

six

The end face of the workpiece is convex or uneven.

When bending, the outer surface of the material is stretched along the circumferential direction to produce shrinkage deformation, and the inner surface is compressed along the circumferential direction to produce elongation deformation, so the bending end surface appears bulging phenomenon along the bending direction.

1. In the final stage of stamping, the punch should have enough pressure.

2. Make the radius of the concave die fillet correspond to the outer fillet of the workpiece.

3. Improve the perfection of the process

seven

Bending leads to hole deformation.

When elastic bending is used and the hole is used for positioning, the outer side of the bending arm is pulled due to the friction between the surface of the female die and the outer surface of the workpiece, so that the positioning hole is deformed.

1. V-bend is adopted.

2. Increase the pressure of the pusher.

3. Add pits on the ejector plate to increase friction and prevent the parts from slipping when bending.

eight

After bending, the accuracy of the position and size of the hole cannot be guaranteed.

1. The expanded size of the part is incorrect.

2. The reason of material springback

3. Unstable positioning

1. Accurate calculation of blank size

2. Add correction program or improve the forming structure of bending die.

3. Change the processing mode or increase the process orientation.

nine

After bending, the axes of the two holes facing each other do not coincide.

The springback of the material changes the bending angle and shifts the center line.

1. Add the calibration process.

2. Improve the bending die structure to reduce material springback.

The bending line is not parallel to the center lines of the two holes.

When the bending height is less than the minimum bending limit height, the bending part will protrude.

1. Increase the height dimension of the bending part.

2. Improve the bending process.

1 1

The cut portion is bent downward.

Because cutting makes the two straight edges open to the left and right, the bottom of the workpiece is deflected.

1. Improve the part structure.

2. Increase the machining allowance at the incision connecting the incision, and then cut off the machining allowance after bending.

After bending, it is deformed in the width direction, and the bent part appears bow deflection in the width direction.

Torsion and deflection are caused by inconsistent stretching and contraction in the width direction of parts.

1. Increase bending pressure

2. Add a calibration program

3. Make sure that the texture direction of the material has a certain angle with the bending direction.

19 how to analyze the trimming die according to the quality of drawing parts?

The causes and adjustment methods of defects in stretched parts are as follows:

serial number

Quality problem

cause analysis

solution

The flange is wrinkled and the wall of the part is broken.

If the blank holder force is too small, the flange part will wrinkle, and the material cannot enter the cavity of the female die and crack.

Increase blank holder force

The flange plane wall is cracked.

Excessive radial tensile stress on materials will lead to dangerous section cracking.

Reduce blank holder force; Increasing the fillet radius of the concave die; Add lubricants or increase the plasticity of materials.

three

The edge of the product is serrated.

There is a burr at the edge of the burr.

Trimming the cutting edge of blank blanking die

four

The edge heights of the parts are inconsistent.

1. The blank center is inconsistent with the punch center, or the material thickness is uneven.

2. The fillet radius of the concave die and the die gap are uneven.

1. Adjust positioning

2. Evenly gap and trim the fillet radius of the die.

five

The dangerous section is obviously thinner.

The radius of die fillet is too small, the blank holder force is too large, and the radial tensile stress of material leads to the necking of dangerous section.

Enlarge the radius and clearance of the die fillet, and apply proper lubricant on the blank.

six

The bottom of the part is pulled off

The fillet radius of the die is too small, and the material is in a cutting state.

Enlarging fillet radius of concave die

seven

Part edge wrinkling

The radius of the die fillet is too large, and the material blank holder that has left the blank holder but has not crossed the die fillet in the unfinished stage of drawing process cannot be pressed down, and it is continuously pulled into the die to form edge wrinkles after wrinkling.

Reduce the radius of concave die fillet or adopt arc blank holder.

eight

The bottom of the product is sunken or bent.

1. The die has no air outlet or the air outlet is too small to be blocked.

2. The contact surface between the ejector pin and the workpiece is too small and the ejector pin is too long.

1. Drill and enlarge air holes.

2. Dressing sprayer

nine

The side wall of a cone or hemisphere is wrinkled.

At the beginning of stretching, most of the materials are suspended, and the BHF is too small. Too large radius of die fillet or too much lubricating oil will reduce the radial tensile stress and increase the tangential tensile stress, which will make the material unstable and wrinkle.

Increase BHF or use drawbead; Reduce the fillet radius of the mold or thicken the material.

Corner fracture of rectangular piece

The radius of the die fillet is too small, the gap is too small or the corner of the workpiece is deformed.

Increase the radius and gap of the die fillet or increase the drawing times (including the intermediate annealing process)

1 1

The upper part of the corner of the rectangular piece is torn off.

There is too much material or burr in the corner of the blank.

Reduce the corner material of the blank or polish the corner burr.

The bottom of the product is uneven.

The blank is uneven, the contact surface between the ejector pin and the workpiece is too small, and the elasticity of the buffer is too small.

Leveling blank and trimming ejection device

The straight wall of the rectangular block is uneven.

The corner gap is too small, and the extrusion of excess material to the side wall is unstable and wrinkled.

Increase the corner clearance and reduce the straight wall clearance.

Part wall roughening

There are burrs on the working plane or fillet radius of the die, and impurities or lubricating oil on the surface of the blank, which causes the surface of the workpiece to be strained.

It is necessary to polish the working surface or fillet of the mold, clean the blank and use clean lubricating oil.

The corners of the rectangular piece are folded inward and partially wrinkled.

The blank holder force at the corner of the material is too small, and pulling it into the cavity of the female die after wrinkling will cause local wrinkling.

Increase blank holder force or increase corner blank area.

The shoulder of the step part is broken.

When the shoulder is formed, the material has excessive tensile stress in the direction of the generatrix.

Enlarge the fillet of die mouth and shoulder or improve lubrication conditions, and choose materials with good plasticity.

How to trim the mould according to the quality analysis of the hole-turning parts?

The causes and adjustment methods of defects in hole-turning parts are as follows:

serial number

Quality problem

cause analysis

solution

The hole wall of the part is not straight.

The gap between the punch and the die is too large or uneven.

Trim or replace punch and die or adjust die gap.

After turning over the hole, the hole is uneven.

1. The gap between punch and die is too small or uneven.

2. The fillet radius of the concave die is uneven.

1. Adjust the mold gap.

2. Trim the fillet of the concave die

three

Fracture of workpiece orifice

1. The gap between the punch and the die is too large.

2. Blank is too hard

3. The stamping part has burrs.

4. The flange of throttle hole is too high.

1. Adjust the reasonable clearance of the mold.

2. Replace the material or anneal the blank.

3. Adjust the die gap or change the feeding direction.

4. Change the process to reduce the flanging height

2 1 how to analyze the trimming die according to the quality of flange parts?

The causes and adjustment methods of flanging parts defects are as follows:

serial number

Quality problem

cause analysis

solution

Flanging is not straight

The gap between the punch and the die is too large or uneven.

Trim or replace punch and die or adjust die gap.

Uneven edge

1. The gap between punch and die is too small or uneven;

2. The fillet radius of the concave die is uneven.

3. Slab deviation

1. Adjust the mold gap.

2. Trim the fillet of the concave die

3. Correct the locating piece

three

There are wrinkles on the edge.

1. The gap between the punch and the die is too large.

2. The shape of the blank outline is abrupt.

1. Trim or replace punch and die.

2. Change the blank shape into a smooth transition.

four

External edge rupture

1. The gap between the punch and the die is too small.

2. The radius of fillet is too small

3. Blank is too hard

1. Adjust the mold gap.

2. Increase fillet radius

3. Replace the material or anneal the blank.

How to trim the continuous die according to the quality analysis of stamping parts?

According to the quality analysis of stamping parts, the method of trimming the continuous die and eliminating the defects of stamping parts is shown in the following table:

serial number

disadvantage?

solution

Punched parts are stuck on the stripper.

Install elastic stripper nails on stripper plate.

Stamping waste sticks to the end face of the punch.

Take various measures to prevent waste from adhering.

three

hoop

Cemented Carbide for Working Parts of Mould

four

impression