Stamping is one of the practical processes for mass production. In the stamping process, the mold has the most problems, it is the most important factor in the production of stamping factors. Directly affect the production efficiency and cost. Affecting the delivery cycle of the product. Mold problems are mainly concentrated in the mold damage, product quality defects and mold grinding, they have long plagued the industry production. Only the correct handling of these key points. Stamping production can be carried out smoothly.
1 die failure
Mold failure is the most prone to stamping production problems, often resulting in shutdown, affecting the production cycle. Therefore, we must find the cause of the mold failure as soon as possible, reasonable maintenance.
1.1 mold damage
Mold damage refers to the mold cracking, breaking, opening, etc., to deal with mold damage, the mold design, manufacturing technology and mold use to find the reasons.
First of all to check the mold manufacturing materials is appropriate, the corresponding thermal burial process is reasonable. In general, the heat treatment process of the mold material has a great influence on it. If the mold quenching temperature is too high, quenching methods and time unreasonable, as well as the number of tempering and temperature, elbow selection between improper, will lead to die into the stamping after production damage. Blanking hole size or depth design is not enough, easy to make the slot blocked, resulting in blanking board damage. The spring force is too small or the contours are so high that the spring is broken and the blanking plate is tilted. The punch is not properly fixed or the screw is not strong enough to cause the punch to fall or break.
When the mold is used, the parts position, direction, etc. are installed incorrectly or the bolts are not fastened. The work height adjustment is too low, the guide column lubrication is insufficient. Feeding equipment failure, press abnormalities, etc., will cause damage to the mold. If there is foreign body into the mold, parts overlap, waste blockage and other conditions are not dealt with in time to continue processing production, it is easy to damage the blanking of the blank, punch, the next template and guide column.
1.2 card model
Stamping process, once the mold is not flexible mold, or even stuck, you must immediately stop production, find out the card model, troubleshooting. Otherwise, will expand the failure, resulting in mold damage.
The main reasons for the card mold are: poor mold orientation, tilt. Or between the template foreign body, so that the template can not be flat; mold strength design is not enough or uneven force. Resulting in mold deformation, such as mold base, the hardness of the template, the thickness of the design is too small, vulnerable to external impact deformation; mold position is not allowed, the upper and lower mold positioning error tolerance. Or the accuracy of the press is too poor, so that the mold interference; punch strength is not enough, the size of the punch too close, so that the lateral force of the mold imbalance. At this time should improve the punch strength, enhance the guidance of the discharge board protection.
1.3 Mold damage and repair
Stamping production of high cost of molds, usually the cost of the total cost of the workpiece 1 / 5-1 / 4. This is because, in addition to mold manufacturing difficult, high cost Put into production after the mold repair and grinding maintenance costs are high, while the original mold cost only about 40% of the total cost of the mold. Therefore, timely maintenance of molds to prevent mold damage, can greatly reduce the stamping production of mold costs.
After the mold is damaged, there is a maintenance and scrapping option. In general. Non-natural wear failure of stamping dies, such as the destruction of non-critical parts. As well as small punch broken, punch upsetting shorter, concave mold plate cracking, punching edge crack, etc. Most of the maintenance method can be completely restored to normal state, re-put into the stamping production. but. When the key parts of the mold seriously damaged, sometimes convex, die at the same time damage. One-time repair costs more than 70% of the original cost of the die, or die life is near. The maintenance of the meaning is not, then you should consider the scrapping die: In addition to large-scale mold, the structure of a complex continuous die. When the mold repair technology is too complex, repair costs too much, the difficulty will inevitably make the maintenance cycle is too long, seriously affect the normal production of stamping, should be selected ahead of schedule scrapped, re-manufacturing mold.
Under normal circumstances, the main failure mode of the die is excessive wear. From the new mold manufacturing delivery. Until the punching parts of the burr exceeded, parts size and shape accuracy of the tolerance, and the mold can no longer repair or no repair value, the mold can only be scrapped. From the new mold put into use to scrapped. Generally have to go through several maintenance and sharpening.
2 parts quality defects
The most common quality defect of the part is the product size. Only a few products have surface quality problems.
2.1 size tolerance
Dimensional tolerance is a serious defect in stamping parts. In this regard, we must first check, check the mold design, remove the design and manufacturing reasons. If the tolerance size and material thickness, should be measured stamping material thickness and material, hardness.
Stamping production process caused by the size of the tolerance, mainly mold wear, poor positioning and deformation of the workpiece. Mold edge wear. Will cause the burr too large or cut the shape becomes larger, punching smaller, flat degree of tolerance, should sharpen or replace the mold. Poor positioning orientation, including no guidance, guide pin or other positioning device does not work, the feeder did not relax, positioning block wear to send too long, the length of the lead plate or the material gap is too large and so on. Parts in the production of deformation, there are impact deformation, such as the product of the blowing pressure is too strong or gravity drop too much deformation: the material by extrusion or injury deformation, should promptly clean up the material location or increase the discharge space : Improper deformation of the top out. For example, improper preparation of the top material, spring force is not appropriate or too long, should adjust the elastic or change the number of positions or pin; Part of the bending pieces can not allow the material overlap, to be dropped every time, when the disc strain can be used to eliminate the pressure pad; punching deformation, the main material distortion. Size increases or center asymmetry; crust extrusion deformation, is due to waste floating or fruiting on the mold surface or foreign objects such as extrusion deformation.
2.2 Surface quality is not qualified
Stamping parts of the surface quality problems, mainly burr too large. Causing the workpiece burr too large, the first is the mold edge of the wear and tear, should re-grinding mold (below), to ensure sharp edge. Followed by convex, concave mold intermittent unreasonable, the gap is too large side of the ambush for the band, the gap is too small will appear secondary shear surface, if the material hardness is too high, you should replace the material or increase the gap. When the blanket is too small or the trimming material is too small, the material is pulled into the mold gap and become burr. At this point you must increase the blanking of the side of the size or trimming margin.
3 mold sharpening
Stamping production of the mold for a reasonable grinding. Can effectively improve the life of the die, save mold costs, significantly reduce product costs.
When the die edge wear to a certain extent, the original sharp edge blunt, and will cause the punching pieces of burr is too large, size and shape accuracy decreased. Therefore, the mold must be sharpened to restore its sharp punching edge. Reduce punching burr and size and shape deviation, improve the surface quality of the forming parts. If not timely grinding mold, because the delay grinding time, making the edge has been blunt hard, too large, too thick burr of the violent friction, the formation of a vicious cycle of excessive wear, leading to several times the grinding So that the edge can be restored to sharp, greatly shorten the life of the mold. When the burrs of the parts are about to exceed the allowable burr height, the production should be stopped immediately and the molds should be sharpened. In the actual production, the scene workers used to determine the size of the burrs and determine the timing of grinding, so that the operation error. It is best to detect the burr height and thickness of the workpiece, burr distribution uniformity, punch size and shape accuracy and punching surface quality, to grasp the edge of the wear and tear, blade 121 blunt degree, so as to determine the best blade Grinding time. # p # Page title # e #
Mold grinding wear must be based on the edge of the face and the side of the actual wear and tear conditions, in addition, should also consider the material thickness, die shape structure and grinding order and other related factors. After the die has been repeatedly sharpened, the size will change, especially the use of small under the large conical concave die design of the punching die, because the die edge of the wall to pour out, sharpen the upper surface of the mold , The horizontal size will inevitably produce an increment. Therefore, before grinding should be calculated in accordance with the angle of the cone, grinding should pay attention to the size of the workpiece, to prevent the number of times due to the workpiece size increase is too large, resulting in product tolerance.