Mold repair refers to the repair work of the mold when the mold can not meet the predetermined use requirements or the parts can not meet the quality requirements. The work was done by the mold repairman. The following introduces the maintenance methods and requirements of several common faults of molds.

A, the blade collapse:

The edge collapse caused by various reasons in the use of the mold will have a certain impact on the quality of the parts. It is one of the most common repair contents in mold repair, and the repair steps of broken edge are as follows:

1. According to the situation of edge collapse, if the edge collapse is very small, it is usually necessary to polish the edge collapse with a grinder to ensure firm welding and avoid edge collapse again;

2. Weld with corresponding covered electrode. At present, we use D332 covered electrode to weld the cutting edge. Before surfacing, the repair datum must be selected, including clearance surface and non-clearance surface;

3. Smooth the gapless surface of the cutting edge (refer to the datum left in advance);

4. Draw a line on the transition piece. If there is no transition piece, the clearance surface can be roughly ground with the reference left in advance;

5. Go to the machine to repair the clearance surface, and use clay and other auxiliary research to match. Be careful in the repair process, start the press as slowly as possible, and adjust the height of the mold to open downward when necessary to avoid the phenomenon of knife edge biting;

6. The blade clearance should be reasonable. For steel plate stamping die, the clearance of single edge knife edge should be 1/20 of the thickness of sheet metal. However, in the actual operation process, as long as the burr of the cut part meets the requirements, the size of the gap can be tested by sheet metal stamping. Generally speaking, the judgment standard of burr size is that the height of burr is not greater than110 of sheet thickness;

7. Check whether the clearance surface of the knife edge is consistent with the shearing direction;

8. After the clearance is matched, smooth the clearance surface of the knife edge with an oilstone to reduce the friction between the plate and the knife edge in production and the resistance of waste falling.

B, burr:

When trimming, punching and blanking parts, it is easy to have too many burrs. The main reasons for burrs are that the gap between the cutting edges of the die is large and the gap between the cutting edges is small:

When the gap is large: the bright band of the section is very small or basically invisible, and the burr is characterized by being thick and large, which is not easy to remove;

Small gap: there are two bright bands on the section. Because of the small gap, the burr is characterized by high and thin.

Repair method when the gap is large:

1. In the process of trimming and punching, the punch is fixed and the female die is trimmed, while in the process of blanking, the female die is taken as the benchmark, that is, the female die size is unchanged and the male die is trimmed. The above difference is to ensure that the product size will not be affected before and after repair;

2. Find out the part where the gap between the die cutting edge and the workpiece is large;

3. Repair welding is carried out on this part with corresponding covered electrode (D332) to ensure the hardness of the die-cutting edge;

4. Repair the gap of the knife edge (the method is the same as the knife edge collapse).

Repair method of small gap:

1. The specific situation is adjusted according to the size of the mold gap to ensure the rationality of the gap. For trimming die, the notch should be placed in the female die, while for blanking die, the method of enlarging the male die should be adopted to ensure that the size of the part will not change before and after repair;

2. After the repair is completed, measure the perpendicularity of the clearance surface, and use the plate to test whether the blade clearance meets the reasonable requirements.

For stamping die, if burr appears after the punch or die is worn, you can find the corresponding standard parts to replace it. If there are no standard parts, they can be made by repair welding or surveying and mapping. In addition, it is pointed out that materials with poor weldability, such as alloy steel, should be welded after special treatment, such as preheating, otherwise the mold will crack.

C. take a nap:

Brush coating mainly occurs in stretching, forming and flanging.

Solution: 1 Firstly, according to the parts, find out the corresponding napping position of the die;

2. Push the corresponding position of the mold with oilstone, and pay attention to the uniform fillet size;

3. Grind the pushing position of the mold with fine sandpaper, and the sandpaper is above 400.

D, trimming and punching:

The main reason for trimming and punching the belt is that the pressing or discharging device of the die is abnormal when trimming or punching.

Solution: 1 According to the parts of the product belt, find out the parts corresponding to the mold;

2. Check whether there is any abnormality on the molded discharging plate;

3. Repair welding the corresponding parts of the blank holder;

4. Combining with the repair and welding of parts, prepare specific profiles and working parts;

5. try to rush;

6. If the inspection is not the problem of the demoulding machine, you can check whether the tool block of the mold has galling phenomenon.

E, waste cutting constantly:

Aiming at the phenomenon of continuous cutting of waste, this paper first analyzes why it doesn't stop. The main reason is that the operator did not clean up the waste in time during the production process, which led to the accumulation of waste, and finally the blade of the waste knife collapsed under the pressure of the upper trimming block. The repair method is similar to the trimming block, so I won't introduce it in detail here, but we must pay attention to the height of the trimming block during the repair process. If the trimming is too high, it will lead to the interference between the cutter block and the upper trimming cutter block, thus causing the waste cutter block to be damaged again; If it is repaired too low, it will cause waste cutting, so when repairing waste knives, not only the clearance surface of the knife block, but also the height of the knife block should be considered. Its repair is more difficult than the simple collapse of the knife edge. But as long as the datum plane is selected before repair, the repair can still be handy.

F, punching waste plugging:

Stamping waste blockage is a common failure of stamping die, probably due to the following reasons: the waste channel is not smooth, the waste channel has an inverted cone, and the waste is not cleaned in time. The following analysis is combined with pictures:

1, lower die holder 2, punching die

As shown in the above figure, the reasons for waste blockage are:

1. Surface A or B is not smooth, and machining lines appear on its surface.

2. The inverted cone appears on the surface A or B, which causes the waste passage to be large and small, thus blocking the waste.

Repair method: As long as the A surface and the B surface are smooth and equal in diameter, the waste will not be blocked.

G, deformation of flanging forming parts:

In the flanging process, the deformation of parts often occurs, which generally does not have much influence on the quality of parts in non-curved parts, but in curved parts, as long as there is a little deformation, it will bring great quality defects to the appearance and affect the quality of the whole vehicle.

Analyze the causes of deformation of parts;

1. Because the sheet metal deforms and flows in the process of forming and flanging, it will deform if the material is not pressed tightly;

2. If the pressing force is large enough, if the pressing surface is uneven and there are gaps locally, the above situation will also occur.

Solution:

1. Increase the pressure. If it is spring pressing, the air cushion can be pressed by adding a spring, usually by increasing the air cushion force;

2. If some areas are still deformed after increasing the pressure, red lead can be used to find out the specific problem point and check whether there is local depression on the pressing surface. At this time, the method of welding pressure plate can be adopted;

3. After welding, the blanking plate is matched with the lower die surface.