Mould repair refers to the repair of the die when the die can not meet the predetermined use requirements or the parts can not meet the quality requirements. This work is done by the die repairman. The repairing methods and requirements for common faults of several dies are described below.
A. Blade breaking:
The blade collapse caused by various reasons in the use of Shandong moulds will have a certain impact on the quality of the parts. It is one of the most common repairing contents in die repairing. The steps of repairing tool edge collapse are as follows:
1. According to the situation of the avalanche, if the avalanche is very small, the avalanche should be grinded by a grinding wheel to ensure that the welding is firm and the avalanche is not easy to occur again. 2. The corresponding electrode is used for welding. At present, D332 electrode is used for surfacing the edge. Before surfacing, it is necessary to select the repair datum surface, including gap surface and non-gap surface; 3. smoothing the non-gap surface of the edge (refer to the datum left beforehand); 4. marking the transition part, if there is no transition part, rough grinding the gap surface with the datum left beforehand; 5. repairing the gap surface with the help of clay and other auxiliary grinding. In the process of repair, care must be taken to start the press as slowly as possible, and adjust the height of the die downward when necessary, so as to avoid the phenomenon of knife-edge gnawing; 6. Knife-edge clearance should be reasonable, for the steel plate stamping die, one-sided knife-edge clearance takes one-twentieth of the thickness of the sheet metal. But in the actual operation process, we can use the method of plate punching to check the gap size, as long as the burr of the cut part meets the requirements. Generally, the criterion for determining the burr size is that the burr height is not more than 1/10 of the thickness of the sheet metal; 7. Whether the gap surface of the cutting edge is consistent with the direction of the cutting; 8. When the gap is matched, the gap surface of the cutting edge is pushed smooth by oil stone. Slip to reduce friction between plate and knife edge and resistance of waste falling in production.
When trimming, punching and blanking, the burr of parts is too large. The main reasons for burr are large clearance of die edge and small clearance of blade edge.
When the clearance is large, the bright band of the section is very small or basically invisible, and the burr is characterized by thick and large burr, which is difficult to remove; when the clearance is small, there are two bright bands in the section. Because of the small clearance, the burr is characterized by high and thin burr.
Repair methods for large clearance:
1. In trimming and piercing process, the punch is fixed and the die is trimmed, while in blanking process, the die is used as the reference, that is, the die size is unchanged, and the punch is trimmed. The above differences are to ensure that the size of the product is not affected before and after repair; 2. Find out the parts with large clearance at the edge of the die; 3. Repair the parts with corresponding welding rods (D332) to ensure the hardness of the die edge; 4. Repair the clearance of the tool edge (the method is the same as the method of tool edge collapse).
Repair method for gap hour:
1. Specific conditions are adjusted according to the size of die clearance to ensure that the clearance is reasonable. For trimming punching die, the gap is placed in the concave die, while for blanking die, the method of enlarging the punch should be adopted to ensure that the dimension of the part remains unchanged before and after repair. 2. After repair, the vertical of the gap surface should be measured, and whether the clearance of the cutting edge of the plate can meet the reasonable requirements.
For punching die, if the punch or die is worn out after burring, the corresponding standard parts can be replaced. If there is no standard parts, it can be manufactured by repair welding or surveying. In addition, it is especially pointed out that for the materials with poor welding performance such as alloy steel, special treatment should be carried out before welding, such as preheating, otherwise the die will crack.
Drawing mainly occurs in drawing, forming and flanging processes.
Solutions: 1. Find out the corresponding position of the die according to the parts; 2. Push the corresponding position of the die with the oil stone, and pay attention to the size of the rounded corners; 3. Polish the pushing part of the die with fine sand paper, and the sand paper is over 400.
D. trimming and punching tapes:
The main reasons for edge trimming and punching strip material are: abnormal pressure or discharge device of die during edge trimming or punching.
Solutions: 1. Find out the corresponding parts of the die according to the parts of the strip; 2. Check whether there is abnormality in the die press-unload plate; 3. Repair welding the corresponding parts of the press-unload plate; 4. Combine the parts to repair the welding parts, and make the specific surface and process parts; 5. Trial punching; 6. If the inspection is not the problem of the die press-unload plate, check whether the knife block of the die has the brushing phenomenon. 。