Precision Mold Design for Stamping Bending Parts
Based on the stent bending blanking process and bending process, Comparative analysis of the process of forming three different stamping process (single processes, complex processes and continuous processes) confirm completion of the blanking, punching and a single procedure completed the bending modulus processes. On the cover of the cold bending stents， right after the cover of the mass production, quality components, and the use of structural components of the analysis, research, in line with lower performance prerequisite to the identification of stampings, Stamping method used to complete the processing components, and a brief analysis of the blank shape, size, layout, the conference board, stamping processes in nature, number and sequence determination. For the process, the center of pressure, the die size and the tolerance of the calculation, design mold. Also analyzes the mold of the main components (such as mould, punch hole punch, unloader device, punch, plate, bending plate etc) design and manufacturing, stamping equipment selection, punch-gap adjustment and establishment of a vital parts machining process. Die requirements set out a detailed list of parts, and gives a reasonable assembly. By fully utilizing modern manufacturing technology to mold traditional mechanical parts for structural improvements, design optimization, process optimization methods can greatly enhance production efficiency, the method of similar products have some reference.
KEY WORDS: stents，mold design，progressive die，punching blanking, bending
1.1 Bending Parts analysis
The bending parts is shown in Figure 1-1:
1.1.1 Analysis of stamping process of bending parts
1. Material: Q235-A steel is ordinary carbon structural steel. It has good plasticity, weldability and pressure processing properties, and is mainly used for engineering structures and mechanical parts with less stress. Comprehensive evaluation is suitable for punching processing.
2, the structure of the workpiece: The shape of the workpiece is relatively simple, and the hole margin is larger than the minimum wall thickness allowed by the convex and concave die (a=6), so a continuous stamping process can be considered.
3, size accuracy: There is no tolerance on the part drawing, which is a free tolerance. The tolerance of the workpiece size is determined according to IT14 level. Generally, the stamping can meet the dimensional accuracy requirements.
4. Conclusion: Can be punched out
The workpiece is a typical blanking piece, which is characterized in that the workpiece size is not large, and the upper and lower sides are symmetrical, the material strength is not high, and the workpiece size is not marked with an obvious angle, so it belongs to a general blanking part. The surface roughness of the cut section of the blanking part is 50Ra/mm. It needs to adopt the IT12 grade punching die to meet the precision requirements of the parts. The mold manufacturing precision is IT10.
The shape of the workpiece is trapezoidal as a whole, and is vertically symmetrical. As can be seen from the given workpiece drawing, there are four circular holes on the workpiece, the diameter of the circle is 8mm, and the radius of the two halves is 8 mm.
The shape of the part is simple and symmetrical, and it consists of an arc and a straight line. The economic accuracy that can be achieved by punching parts is IT12~IT13. Comparing the above accuracy with the dimensional tolerances indicated in the part sketch, it can be considered that the accuracy requirements of the part can be guaranteed in the blanking process. Other dimensions, production batches, etc., also meet the punching process requirements, so it is decided to use the progressive punching die for blanking punching and single-step die bending.
1.1.2 Analysis and comparison and determination of stamping process plan
Judging from the structural characteristics of the parts and the characteristics of stamping deformation, the stamping process of the parts has two kinds of punching and blanking. Depending on the possible combination of process properties, the possible stamping options for the part are:
The workpiece includes two basic processes of punching and blanking, and the following three process schemes are available:
Option 1: First blanking, then punching. Produced in a single process.
Option 2: blanking-punching composite stamping. Produced using a composite mold.
Option 3: Punching - blanking continuous stamping. Produced in continuous mode.
The scheme of the first scheme is simple, but two molds are required in two processes, and the cost is high and the production efficiency is low, which is difficult to meet the requirements of medium-volume production.
Scheme 1, the mold structure is simple, but two molds are required in two processes.
High cost and low production efficiency make it difficult to meet high-volume production requirements.
Scheme 2, only a pair of molds. The precision and production efficiency of the workpiece are high, the strength of the mold is poor, and the manufacturing is difficult. At the same time, blanking and punching require a large punching force, so that large punching equipment must be used, resulting in waste of energy.
At the same time, the strength and rigidity of each part of the mold are difficult to guarantee. And after the stamping, the finished part remains on the mold, which will affect the stamping speed when cleaning the material on the mold, and the operation is inconvenient. If the waste material is accumulated in the convex and concave mold, the bulging force on the convex and concave molds is increased, and the cutting edge is easily broken. For the sake of safety, the accumulation of waste in the convex and concave molds should be avoided.
Scheme 3, only one pair of molds, high production efficiency. The inner shape of the part structure is decomposed into a simple shape of a trace die or a female die, and the stamping is performed step by step at different stations. The mold strength and mold life are improved, the operation is convenient, and the workpiece precision can meet the requirements.
Since the workpiece and the hole waste can be discharged under the press table, the operation is convenient and safe, and the production efficiency is high.
At the same time, if there is no elastic (spring and rubber) unloading device on the continuous die, continuous punching can be performed on the high-speed punching machine, and the composite die is difficult. The punched holes can be used to position the pilot pins, thus ensuring the accuracy of the workpiece.
Through the analysis and comparison of the above three schemes, the stamping production of the piece adopts the third scheme.
KEY WORDS: stents，mold design，progressive die，punching blanking, bending
1.1 Bending Parts analysis
The bending parts is shown in Figure 1-1:
Figure 1-1 Parts drawing
1.1.1 Analysis of stamping process of bending parts
1. Material: Q235-A steel is ordinary carbon structural steel. It has good plasticity, weldability and pressure processing properties, and is mainly used for engineering structures and mechanical parts with less stress. Comprehensive evaluation is suitable for punching processing.
2, the structure of the workpiece: The shape of the workpiece is relatively simple, and the hole margin is larger than the minimum wall thickness allowed by the convex and concave die (a=6), so a continuous stamping process can be considered.
3, size accuracy: There is no tolerance on the part drawing, which is a free tolerance. The tolerance of the workpiece size is determined according to IT14 level. Generally, the stamping can meet the dimensional accuracy requirements.
4. Conclusion: Can be punched out
The workpiece is a typical blanking piece, which is characterized in that the workpiece size is not large, and the upper and lower sides are symmetrical, the material strength is not high, and the workpiece size is not marked with an obvious angle, so it belongs to a general blanking part. The surface roughness of the cut section of the blanking part is 50Ra/mm. It needs to adopt the IT12 grade punching die to meet the precision requirements of the parts. The mold manufacturing precision is IT10.
The shape of the workpiece is trapezoidal as a whole, and is vertically symmetrical. As can be seen from the given workpiece drawing, there are four circular holes on the workpiece, the diameter of the circle is 8mm, and the radius of the two halves is 8 mm.
The shape of the part is simple and symmetrical, and it consists of an arc and a straight line. The economic accuracy that can be achieved by punching parts is IT12~IT13. Comparing the above accuracy with the dimensional tolerances indicated in the part sketch, it can be considered that the accuracy requirements of the part can be guaranteed in the blanking process. Other dimensions, production batches, etc., also meet the punching process requirements, so it is decided to use the progressive punching die for blanking punching and single-step die bending.
1.1.2 Analysis and comparison and determination of stamping process plan
Judging from the structural characteristics of the parts and the characteristics of stamping deformation, the stamping process of the parts has two kinds of punching and blanking. Depending on the possible combination of process properties, the possible stamping options for the part are:
The workpiece includes two basic processes of punching and blanking, and the following three process schemes are available:
Option 1: First blanking, then punching. Produced in a single process.
Option 2: blanking-punching composite stamping. Produced using a composite mold.
Option 3: Punching - blanking continuous stamping. Produced in continuous mode.
The scheme of the first scheme is simple, but two molds are required in two processes, and the cost is high and the production efficiency is low, which is difficult to meet the requirements of medium-volume production.
Scheme 1, the mold structure is simple, but two molds are required in two processes.
High cost and low production efficiency make it difficult to meet high-volume production requirements.
Scheme 2, only a pair of molds. The precision and production efficiency of the workpiece are high, the strength of the mold is poor, and the manufacturing is difficult. At the same time, blanking and punching require a large punching force, so that large punching equipment must be used, resulting in waste of energy.
At the same time, the strength and rigidity of each part of the mold are difficult to guarantee. And after the stamping, the finished part remains on the mold, which will affect the stamping speed when cleaning the material on the mold, and the operation is inconvenient. If the waste material is accumulated in the convex and concave mold, the bulging force on the convex and concave molds is increased, and the cutting edge is easily broken. For the sake of safety, the accumulation of waste in the convex and concave molds should be avoided.
Scheme 3, only one pair of molds, high production efficiency. The inner shape of the part structure is decomposed into a simple shape of a trace die or a female die, and the stamping is performed step by step at different stations. The mold strength and mold life are improved, the operation is convenient, and the workpiece precision can meet the requirements.
Since the workpiece and the hole waste can be discharged under the press table, the operation is convenient and safe, and the production efficiency is high.
At the same time, if there is no elastic (spring and rubber) unloading device on the continuous die, continuous punching can be performed on the high-speed punching machine, and the composite die is difficult. The punched holes can be used to position the pilot pins, thus ensuring the accuracy of the workpiece.
Through the analysis and comparison of the above three schemes, the stamping production of the piece adopts the third scheme.
