The mold mainly realizes the processing of the shape of the article by changing the physical state of the molding material. The following is an introduction to the design and production skills of stamping die that I have compiled. Let's have a look.

I. Information from the waste situation

The waste is essentially the reverse image of the forming hole. That is, the same part in the opposite position. By checking the waste, it can be judged whether the gap between the upper and lower dies is correct. If the gap is too large, rough and undulating fracture surfaces and narrow bright areas will appear in the waste. The larger the gap, the larger the angle between the fracture and the bright area. If the gap is too small, the waste will show a small angle fracture and a wide bright zone.

Too large a gap forms a hole with a large curl and edge tearing, so that the thin edge of the cross section protrudes slightly. Too small a gap will form a strip with slight curl and large angle tear, resulting in a cross section more or less perpendicular to the material surface.

The ideal waste should have a reasonable collapse angle and a uniform bright area. This can keep the punching force to a minimum and form a clean round hole with few burrs. From this point of view, extending the die life by increasing the gap is at the expense of the quality of the finished hole.

Second, the choice of mold clearance

The clearance of stamping die is related to the type and thickness of stamping material. Unreasonable clearance will lead to the following problems:

(1) The gap is too large, the burr of the stamping workpiece is large, and the stamping quality is poor. If the gap is too small, although the stamping quality is better, the die wear is more serious, which greatly reduces the service life of the die and easily causes the punch to break.

(2) Too large or too small a gap may cause adhesion on the punch material, thus causing material entrainment in the stamping process. If the gap is too small, it is easy to form a vacuum between the bottom surface of the punch and the sheet metal, and the waste will rebound.

(3) Reasonable clearance can prolong the service life of the die, with good discharging effect, reduce burr and flanging, keep the plate clean, keep the aperture consistent, avoid scratching the plate, reduce polishing times, keep the plate straight and punch accurately.

Third, how to improve the service life of the mold

For users, improving the service life of the die can greatly reduce the stamping cost. The factors affecting the service life of the mould are as follows:

1, type and thickness of materials;

2, whether to choose a reasonable gap between the lower dies;

3. Mold structure;

4. Whether the materials are well lubricated during stamping;

5. Whether the mold has undergone special surface treatment;

6, such as titanium plating, titanium carbonitride;

7. Alignment of upper and lower turntables;

8. Adjust the rational use of gaskets;

9, whether the appropriate use of inclined blade mold;

10, whether the die base of the machine tool is worn;

Fourth, the problems that should be paid attention to in stamping holes with special sizes

(1) Minimum aperture impulse? Please use a special punch to punch holes in the range of 0.8 1.6.

(2) When punching a thick plate, please use a die with a larger aperture than the processing. Note: At this time, if you use a die of normal size, the thread of the punch will be damaged.

(3) The ratio of the minimum width to the length of the punch cutting edge should generally not be less than 1: 10.

(4) The relationship between the minimum size of the cutting edge part of the punch and the plate thickness. It is suggested that the minimum size of the cutting edge of the punch should be twice the thickness of the plate.

5, grinding the mold

1, the importance of mold grinding

Regular sharpening is the guarantee of stamping quality consistency. Sharpening the knife regularly can not only improve the service life of the mold, but also improve the service life of the machine. It is necessary to grasp the correct polishing opportunity.

2. The specific features of the mold that need sharpening.

There is no strict number of blows to determine whether it is necessary to polish the mold. Mainly depends on the sharpness of the cutting edge. Mainly determined by the following three factors:

(1) Check the fillet of the cutting edge. If the radius of fillet reaches R0. 1mm (the maximum R value shall not exceed 0.25mm), it needs to be sharpened.

(2) Check the punching quality to see if there are big burrs.

(3) Judging whether sharpening is needed by the noise of machine stamping. If the noise of the same pair of dies is abnormal, it means that the punch is blunt and needs sharpening.

Note: If the edge of the cutting edge is round or the back of the cutting edge is rough, grinding should also be considered.

3, grinding method

There are many ways to sharpen molds, which can be realized by special grinder or surface grinder. The grinding frequency of punch and lower die is generally 4: 1. Please adjust the mold height after grinding.

(1) Harm of incorrect grinding method: Incorrect grinding will aggravate the rapid damage of die-cutting edge, resulting in a greatly reduced number of blows per grinding.

(2) Benefits of correct sharpening method: Regular sharpening of the die can keep the quality and precision of punching stable. The cutting edge of the die will be damaged slowly, and the service life will be longer.

4, grinding rules

The following factors should be considered when grinding the mold:

(1) In the case of R 0. 1-0.25mm, the fillet of the cutting edge depends on the sharpness of the cutting edge. ..

(2) The grinding wheel surface should be cleaned.

(3) It is recommended to use loose, thick and soft grinding wheels. Such as WA46KV

(4) The grinding amount (cutting amount) shall not exceed 0.0 13mm at a time. Excessive grinding will lead to overheating of the mold surface, which is equivalent to annealing treatment, and the mold will become soft, greatly reducing the life of the mold.

(5) When grinding, enough cooling liquid must be added.

(6) When grinding, the punch and the lower die should be fixed firmly, and special fixtures should be used.

(7) The grinding amount of the die is certain. If this value is reached, the punch will be scrapped. If you continue to use it, it is easy to cause damage to the mold and machine, which is not worth the loss.

(8) After grinding, the edges should be treated with oilstone to remove excessively sharp edges.

(9) After polishing, it should be cleaned, demagnetized and oiled.

Note: The grinding amount of the die mainly depends on the thickness of the punching sheet.

Six, punching machine should be paid attention to before use

1, store

(1) Wipe the inside and outside of the upper die sleeve with a clean rag.

(2) During storage, be careful not to leave scratches or dents on the surface.

(3) Oil for rust prevention.

2. Preparation before use

(1) Clean the upper die sleeve thoroughly before use.

(2) Check the surface for scratches and dents. If so, remove it with an oilstone.

(3) Internal and external oil.

3. Matters needing attention when installing the punch on the upper die sleeve

(1) Clean the punch and grease its long handle.

(2) Insert the punch into the bottom of the upper die sleeve on the large-station die, and do not use force. You can't use a nylon hammer. During installation, the punch cannot be fixed by screwing the bolt on the die sleeve, and the bolt can only be screwed on after the punch is correctly positioned. The content of Zhengquan Technology WeChat is really good and worthy of attention!

4. Install the upper die assembly into the turret.

If you want to prolong the service life of the die, the gap between the outer diameter of the upper die sleeve and the turret hole should be as small as possible. Therefore, please perform the following procedures carefully.

(1) Clean the inside diameter of keyway and turret hole and oil it.

(2) Adjust the keyway of the upper die guide sleeve to match the key of the turret hole.

(3) Insert the upper die sleeve straight into the tower hole, and be careful not to have any inclination. The upper die guide sleeve should slide into the turret hole by its own weight.

(4) If the upper die sleeve leans to one side, soft material tools such as nylon hammer can be used to knock gently and repeatedly until the upper die guide sleeve slides into the correct position by its own weight.

Note: Do not apply force on the outer diameter of the upper die guide sleeve, only on the top of the punch. Don't knock on the top of the upper die sleeve to avoid damaging the turret hole and shortening the service life of individual stations.

Seven, mold maintenance

If the punch is bitten by material and cannot be taken out, please check it according to the following items.

1, the punch and the lower die are sharpened again. A mold with a sharp blade can produce a beautiful cutting surface. If the cutting edge is blunt, extra punching force is needed, and the cross section of the workpiece is rough, resulting in great resistance, which leads to the punch being bitten by the material.

2. Clearance of the mold. If the gap of the die is not properly selected relative to the thickness of the plate, the punch needs a great demoulding force when it is separated from the material. If the punch is bitten by the material for this reason, please replace the lower die with a reasonable clearance. The content of Zhengquan Technology WeChat is really good and worthy of attention! !

3, the state of processing materials. When the material is dirty, or there is dirt, the dirt adheres to the die, so that the punch is bitten by the material and cannot be processed.

4. Deformed materials. The tilted material will clamp the punch after punching, so that the punch will be bitten. Warp materials should be leveled before processing.

5. Excessive use of springs. It will make spring tired. Please check the performance of the spring frequently.

Eight, come on

Oil quantity and fuel injection times depend on the conditions of processing materials. Cold-rolled steel plate, corrosion-resistant steel plate and other rust-free and scale-free materials should be oiled in the mold, and the oiling points are the guide sleeve, the oil inlet, the contact surface between the tool body and the guide sleeve, and the lower mold. Light engine oil for engine oil.

For materials with rust and scale, rust micro-powder will be sucked between the punch and the guide sleeve during processing, resulting in dirt, which makes the punch unable to slide freely in the guide sleeve. In this case, if oiled, the rust will be easier to get on. Therefore, when washing this material, it is necessary to clean the oil, decompose it once a month, remove the dirt on the punch and the lower die with gasoline (diesel oil), and then clean it before reassembly. This can ensure that the mold has good lubrication performance.

Nine, the mold often appear in the process of using problems and solutions.

Problem 1: The plate is separated from the pliers mouth.

Reason: The mold was not completely discharged.

Solution:

1. Use an inclined punch.

2. Apply lubricant to the board.

3. Adopt heavy mould

Second, the mold is seriously worn.

Reason: Unreasonable (small) mold clearance.

Solution: Increase the mold clearance.

Cause: The upper and lower die holders are not aligned.

Solution:

1. Station adjustment, centering of upper and lower dies.

2. Horizontal adjustment of turntable

Reason: The worn mold guide assembly and turret insert were not replaced in time.

Solution: replacement

Cause: The punch is overheated.

Solution:

1, add lubricant to the sheet metal.

2. Ensure the lubrication between the punch and the lower die.

3. Use multiple sets of molds with the same specifications and sizes in the same program.

Cause: Improper grinding method leads to die annealing, which leads to increased wear.

Solution:

1, using soft abrasive grinding wheel.

2, often clean the grinding wheel

3, a small number of knives.

4. Sufficient coolant

Reason: small step distance

Solution:

1, increase the step.

2, the use of bridge step punch.

Problem 3: Adhesion of perforated tape and perforation

Reason: Unreasonable (small) mold clearance.

Solution: Increase the mold clearance.

Cause: The cutting edge of the punch is blunt.

Solution: Sharpen in time

Cause: Poor lubrication.

Solution: Improve the lubrication conditions.

Question 4: Scrap rebound

Cause: Lower die problem

Solution:

1, use bulletproof material to lower the mold.

2. For small diameter holes, the clearance is reduced by 10%.

3. When the diameter is greater than 50.00 mm, the gap is enlarged.

4. Scratches were added on the cutting edge side of female die.

Reason: punching in.

Solution:

1, increase the depth of the mold.

2. Install the discharging polyurethane ejector pin.

3. Use an inclined cutting edge

Question 5. Unloading difficulty

Reason: Unreasonable (small) mold clearance.

Solution: Increase the mold clearance.

Cause: The punch is worn.

Solution: Sharpen in time

Cause: Spring fatigue

Solution: Replace the spring.

Cause: Punching adhesion

Solution: Remove the adhesion.

Question 6. Stamping noise

Cause: It is difficult to discharge.

Solution:

1, which increases the clearance of the lower die and ensures good lubrication.

2, increase the intensity of unloading

3. Use the unloading plate with soft surface.

Cause: There is something wrong with the plate support on the workbench and in the turret.

Solution:

1, using spherical support mold.

2. Reduce the working size

3, increase the working thickness

4. Plate thickness

5. Punching holes with oblique edges.

X. Matters needing attention in using special molding tools

1, different types of machines have different slider strokes, so attention should be paid to the adjustment of the closing height of the molding die.

2. It is necessary to ensure sufficient molding, so it needs to be carefully adjusted, and the adjustment amount at a time cannot exceed 0.15 mm.. If the adjustment amount is too large, it is easy to cause damage to the machine and mold.

3. During stretch forming, please choose a light spring assembly to prevent the sheet from tearing, otherwise it will be difficult to discharge due to uneven deformation. The content of Zhengquan Technology WeChat is really good and worthy of attention! !

4. Install a spherical supporting die around the forming die to prevent the plate from tilting.

5. The molding position should be as far away from the fixture as possible.

6, forming processing is best placed at the end of the processing program to achieve.

7. Make sure the plate is well lubricated.

8. Pay attention to the problem of making way for special molding tools when ordering. If the distance between the two molding tools is relatively close, please be sure to communicate with our salesman.

9. Because the molding tool needs a long discharging time, it must be processed at a low speed, preferably with a delay.

XI。 Matters needing attention in using rectangular cutter

1, the step distance should be as large as possible, accounting for more than 80% of the whole tool length.

2. It is best to realize skipping through programming.

3. It is suggested to choose the inclined cutting edge die.

Twelve. How to punch holes without exceeding the nominal force of the machine?

In the production process, it is necessary to drill a circular hole with a diameter larger than 1 14.3 mm, and such a large hole will exceed the upper limit of the nominal force of the machine, especially for materials with high shear strength. This problem can be solved by making a few big holes. Cutting along the circumference of a big circle with a small mold can reduce the punching force by half or more, which may be achieved by most of the molds you already have.

Thirteen, a simple way to make a big round hole

The mold of this convex lens can be made into the radius you need. If the aperture exceeds the nominal force of the punch, we recommend scheme (a). Punch a circle with this mold. If the aperture can be punched within the nominal force range of the punch, a radial die and a convex lens die can punch the required hole within four times without rotating the die (B).

Fourteen, finally forming downward.

When selecting the forming die, the downward forming operation should be avoided, because it will occupy too much vertical space and lead to the extra process of flattening or bending the plate. The downward forming may also be caught by the lower die and then pulled out of the turret. However, if downward molding is the only process choice, it should be regarded as the last treatment process of the plate.

Fifteen, to prevent material deformation

If a large number of holes need to be punched in the plate, and the plate cannot be kept flat, the reason may be the accumulation of stamping stress. During drilling, the material around the hole is pulled down, which increases the tensile stress on the upper surface of the plate and the compressive stress on the lower surface of the plate. The result is not obvious when the number of holes is small, but with the increase of the number of holes, the tensile stress and compressive stress also increase exponentially until the plate is deformed. The content of Zhengquan Technology WeChat is really good and worthy of attention! !

One way to eliminate this deformation is to drill a hole every other hole, and then go back to drill the rest. Although this produces the same stress on the plate, it collapses the accumulation of tensile stress/compressive stress produced by stamping one after another in the same direction. This also makes the first batch of holes share part of the deformation effect of the second batch of holes.

;