According to the national occupation definition, mold design is: engaged in the enterprise mold digital design, including cavity mold and cold press mold, in the traditional mold design, based on the full application of digital design tools, improve the quality of mold design, shorten the mold design cycle of the personnel. 1, the composition of the template
The composition of the stamping die will be based on the type of mold and the composition and the difference, there is a smooth configuration type structure and reverse configuration type structure of the two categories. The former is the most commonly used structure, the latter structure is mainly used for drawing forming molds or with special molds.
2. Mold specifications
(1). Mold size and locking screws
The size of the template should be larger than the working area, and choose the standard template size. The position of the template locking screws is related to the type of mold and the size of the template. One of the most commonly used locking screws for single project molds are configured in the corners of the four corners, the most standard form of the work area can be widely used. Longer molds and continuous molds most often use locking screws configured in the corners and middle position.
(2). Thickness of the template
The selection of the thickness of the template is absolutely related to the structure of the mold, the type of stamping process, the processing force of the stamping process, and the precision of the stamping process, etc. The theoretical calculation determines the thickness of the mold. Based on theoretical calculations to determine the thickness of the mold is difficult, generally by experience, the design of the template thickness should be used as little as possible, with the height of the mold and clamping height to be standardized in order to facilitate the procurement and inventory management. Continuous mold of the main template has a punch fixed plate, pressure plate, concave template, etc., the structure of the design according to the precision of the stamping products, the number of production, the mold of the processing equipment and processing methods, maintenance of the mold in the following three forms: (1) the whole block, (2) yoke type, (3) inlay type.
1. Block type
The block type template is also known as a one-piece construction type, its processing shape must be closed. Integral template is mainly used for simple structure or precision molds, its processing mode to cutting-based (no heat treatment), the use of heat treatment of the template must be implemented again wire cutting or electrical discharge machining and grinding process. Template size long (continuous mold) of the occasion will use two or more pieces of one body type and use.
2. Yoke type
The center part of the yoke type template is processed into a concave groove to assemble the block. Its structure according to the application requirements, concave groove part can be formed by other templates. The advantages of this yoke type formwork structure are: the groove is easy to process, the width of the groove can be adjusted, and the processing accuracy is good, etc. However, the low rigidity is its disadvantage. But low rigidity is its disadvantage.
The yoke formwork design considerations are as follows:
(1). Yoke plate components and block parts embedded in the middle of the fit or light with the way, such as the use of strong pressure with the yoke plate will change.
(2). The yoke plate also has the function of keeping the block part, in order to bear the side pressure and surface pressure of the block part, it must have enough rigidity. And in order to make the yoke plate groove part and block parts to get close to the combination of its groove part of the corner for the escape gap processing, such as the yoke plate groove part of the corner can not be made into the escape gap processing, then the block parts must be made into the escape gap processing.
(3). The division of the block part should also consider its internal shape, the reference surface must be clarified. In order to avoid deformation during the stamping process, the shape of each block part should also be paid attention to.
(4). When the yoke plate is assembled into many pieces of block parts, the accumulated processing error of each block part makes the pitch change, and the solution is to design the middle block part in an adjustable way.
(5). The block part adopts the side-by-side combination of the mold structure, due to the block part will be subjected to side pressure when punching and cutting processing, so that the gap between the block part or cause the block part of the tilt. This phenomenon is an important cause of stamping defects such as dimensional defects and chip blockage, so adequate countermeasures must be taken.
(6). There are five fixing methods for the block parts in the yoke plate according to their size and shape: A. Fixed by locking screws, B. Fixed by keys, C. Fixed by key, D. Fixed by shoulder, E. Fixed by pressing on the upper pressure parts (such as guide plate).
3. Inserted
The template is processed in the round or square concave part, and the block part is embedded in the template, this template is called inserted structure, the cumulative machining tolerance is less, the rigidity is high, and the accuracy of the decomposition and assembly is good reproducibility. Due to the advantages of easy machining, machining accuracy determined by the working machinery, the final adjustment of the project less, the inserted template structure has become the mainstream of precision stamping die, but its disadvantage is the need for high-precision hole processing machine.
When this template structure is adopted for continuous stamping molds, the empty station is designed to make the template have high rigidity requirements. The precautions for the construction of the insert mold plate are as follows:
(1). Embedded hole processing: the embedded hole processing of the template using vertical milling machine (or jig milling machine), integrated processing machine, jig boring machine, jig grinder, wire cutting discharge processing machine. The embedded holes of the processing standard, the use of wire cutting and electrical discharge machining machine, in order to improve its processing accuracy is to carry out two or more wire cutting processing.
(2). Fixing method of inserts: The determining factors of fixing method of inserts are the accuracy of processing without changing, the ease of assembly and disassembly, and the possibility of adjustment. There are four fixing methods for inserts as follows: A. Screw fixing, B. Shoulder fixing, C. Toe block fixing, and D. Upper part of the insert is pressed with a plate. Concave template of the embedded parts of the fixing method is also used to press into the fit, at this time should be avoided due to the processing of thermal expansion and the result of the relaxation, the use of round die set embedded parts processing irregular holes should be designed to prevent the method of rotation.
(3). Consideration of assembly and disassembly of inserts: Inserts and their holes require high machining accuracy to be assembled. In order to get even if there is a slight dimensional error can be adjusted in the assembly, it is advisable to consider the countermeasures in advance, the specific considerations for the processing of inserts are the following five items: A. There is a press into the introduction of the part, B. To adjust the insert of the press into the state and the correct position of the spacer, C. Inserts are equipped with holes in the bottom of the press out with the D. Screws should be used in the same size screws in order to facilitate the locking and unlocking, E. In order to prevent errors in the direction of the formation, it is necessary to use the same size screws. E. In order to prevent the error of cubic direction, should be designed to prevent the chamfering process.
Design
1. Unit
The mold alignment unit is also known as the mold edge parts of the alignment guide device. In order to maintain the alignment of the upper and lower molds and shorten the preparation time, according to the requirements of product precision and production volume, there are five main types of mold alignment units:
(1). No guide type: The mold is installed in the punch press to carry out the alignment operation of its edge parts directly, without using the guide device.
(2). External guide type: This device is the most standard structure, the guide device is installed in the upper die holder and the lower die holder, not through the template, generally known as the die holder type.
(3). External guide and internal guide are used together (1): This device is the most commonly used structure for continuous molds, and the internal guide is installed between the punch fixing plate and the press plate. The punch and the concave mold are aligned with the fixing pin and the outer guide. Another function of the inner guide is to prevent the press plate from tilting and to protect the small punches.
(4). External guide and internal guide are used together (2): This type of device is used in high precision, high speed and continuous molds. The internal guide runs through the punch fixing plate, the press plate and the concave mold fixing plate, etc. The internal guide itself also has a mold fixing pin, which is used for the mold. The inner guiding device itself also has the role of mold edge alignment and protection of small punches. The main role of the outer guide is to disassemble the mold and install it on the punch press to get the smooth purpose.
(5). Inner guide type: This structure does not use the outer guide, the inner guide runs through the punch fixing plate, press plate and concave die fixing plate, etc., to maintain the positional relationship of each plate correctly to protect the punch.
2. Guide pillar and guide sleeve unit
There are two types of guide pillar and guide sleeve unit for the mold guidance and accessories: (A). External guide type (mold base type or main guide), (B). Inner guide type (or auxiliary guide). In addition, to meet the requirements of precision molds, there is a high demand for the use of both external and internal guide types.
(1). Outer guide type: Generally used in molds that do not require high precision, mostly with the die base constitutes a unit of trafficking, the main role of the mold is installed in the punch press when the edge of the pieces of the alignment, almost no stamping process in the dynamic accuracy of the maintenance of the effect.
(2). Internal guide type: Due to the progress of the mold processing machine, the rapid popularization. In addition to the main role of the mold installed in the punch press, the edge of the pieces of the alignment, but also have the dynamic accuracy of the stamping process to maintain the effect.
(3). Outer guide and inner guide type: A mold uses both outer guide and inner guide devices.
3. Punch and die unit (round)
(1). Punch unit: The round punch unit is suitable to be used in conjunction with the platen guide unit according to its shape (shoulder type and flat type), length, and ease of maintenance.
(2). Concave die unit: Round concave die unit is also called concave die guide sleeve unit, its form has a whole piece type and separate type, according to the number of production, service life and products or punching chip processing, the combination of concave die unit series are: (A). Directly processed concave mold shape using template, (B). The clearance section with two oblique angles, (C). Whether or not to use a backing plate, (D). Irregular concave mold shapes must be designed to prevent rotation.
4. Pressure bolt and spring unit
(1) Pressure bolt unit: The types of pressure plate bolts are: (A). External screw type, (B). Sleeve type, (C). Internal screw type. In order to keep the clamping plate parallel to the specified position, the stopping method of the clamping bolt (shoulder contact area): (A). Die holder recess bearing surface, (B). Top surface of punch fixing plate, (C). Top surface of punch back plate.
(2) Pressure spring unit: The movable pressure plate pressure spring unit can be broadly divided into: (A). (B). With compression bolts and type
Selection of compression spring unit is best to consider the following points before deciding:
(A), to ensure that the free length of the spring and the necessary amount of compression (compression of the spring should be placed in the compression of the plate cavity).
(B) Adjustment of initial spring compression (pre-compression) or load is necessary.
(C) Consider how easy it is to set up or maintain the mold.
(D) Consider the relationship with the length of the punch or press bolt.
(E) Considering the safety (preventing the spring from flying out when it breaks).
5. Guide pin unit (positioning of bar feeding direction)
(1) Guide pin unit: The main function of the guide pin is to get the correct feeding pitch during continuous stamping process. There are two types of guide units for stamping dies: indirect type (guide pins are used separately) and direct type (guide pins are installed inside the punch).
(2) The guide pin is assembled in the same way as the punching head (mounted on the punch fixing plate). The spring is used to restrain it to the punch fixing plate.
(3) The guide pin is additionally mounted on the press plate. Since the guide pin is required to protrude from the press plate by a certain amount and to prevent it from easily taking up the processed material when the mold rises, it is necessary to pay attention to the rigidity of the press plate and the form of the guide pin.
(4), the guide pin unit has a direct type, which is installed in the punch, mainly used for the shape of the punching (downstream processing) or the lead engineering of the cutting edge processing, the location of the positioning is to use the products of the holes and the lead part of the inner diameter.
6. Guide unit
(1) In the case of profile punching (undercutting) or continuous stamping, a guide unit is used to guide the width of the material to be processed and to obtain the correct feeding pitch.
(2) The guiding device for the width direction of the material strip, the guiding methods are: (A). Fixed plate guide pin type, (B). Movable guide pin type, (C). Plate tunnel guide type (single plate), (D). Plate guide type (two-piece construction), (E). Lifting pin guided type (movable type, fixed type or both).
(3), start and stop the guide device, the form of: (1). Slider type, (2). Movable pin type and so on two kinds, the main role is the material placed in the mold of the initial starting position positioning.
(4), feeding stop device, can correctly determine the feeding pitch, mainly used for manual feeding occasions, the form of: (A). Fixed stop pin, (B). Movable stop pin, (C). Side cut stop, (D). Hook stop mechanism, (E). Automatic stop mechanism.
(5). Side-push type material guide mechanism, the material is pressed to one side during stamping process, which can prevent the snaking phenomenon caused by the difference between the width of the material strip and the width of the material guide.
(6), the embryonic material position positioning guide mechanism, the form of: (A). Fixed pin guide type (using the shape of the embryo material), (B). Fixed pin guide type (utilizing the hole of the blank), (C). Guide plate (for large parts), (D). Guide plate (one piece), (E). Guide Plate (Split Shape).
7. Lifting and jacking unit
(1), lifting pin unit: its main role is to carry out continuous stamping process will be the material bar up to the concave die (the position of the height is called the height of the feed, and to achieve the purpose of smooth feeding, the form of: (A). The lifting pin type (round, purely for lifting material) is the most common type of lifting pin unit. (B). Lifting pin type (round, with holes for guide pins), the lifting pin is equipped with holes for guide pins to prevent the deformation of the material subjected to the guide pins and to enable the guide pins to actually function. (C). Rising material and guide pin type, both with the function of material guide, continuous mold material guide most often use this form of rising material pin type. (D). Rising pin type (square) with air blow holes if required. (E). Lifting pin and guide pin type (square).
(2) Ejector unit: In automatic stamping process, it is necessary to prevent the jumping of punched products or punched chips on the surface of the concave die in order to avoid the damage of the die and the generation of defective stamped parts.
(3) Ejector unit: The main function of the ejector unit is to eject the products or scraps from the concave die every time the stamping process. Ejector unit is installed in two places: (A), reverse configuration mold fashion installed in the upper mold part, (B). Shun-configuration type molds are installed in the lower mold part.
8. Fixed pin unit
The shape and size of the fixed pin unit are designed according to the standard specifications, and the precautions to be taken when using the unit are: (A). Fixed pin holes should be through holes, can not be occasions, consider easy to use screws to remove the design method. (B). The length of the fixing pin should be moderate, not greater than the necessary length. (C). The hole for the retaining pin should have the necessary escape part. (D). When placed in the upper mold section, a mechanism should be designed to prevent it from falling. (E). In the case of press-fit and slide-fit, the hole for the retaining pin on the sliding side should be slightly larger than the retaining pin. (F). The number of retaining pins should be two, and the same size should be chosen as much as possible.
9. Pressure plate unit
Pressure plate unit is especially important to have the correct parallelism between the pressing surface and the concave mold surface and the balance of cushioning pressure.
10. Misfeed Detection Unit
When stamping with a continuous die, the die must be designed with a failure detection unit to detect if the change in feed pitch exceeds the standard and stop the press from running. The error detection unit is installed inside the mold, and according to its detection method, there are the following two installation forms: (A). (A) The detection pin is installed in the upper mold, when it deviates from the hole of the bar, it will be detected by contacting with the bar. (B). The lower mold is equipped with a detector pin that detects when a part of the bar is in contact with the detector pin.
11. Waste cut-off unit
Continuous stamping process when the strip (waste) will leave the mold one after another, there are two ways to deal with it: (A). (A). The strip will be rolled up by the coiling machine, and (B). Using the mold cutting device to refine it. The latter can be done in two ways: (A). Using a special scrap cutter (installed outside the press machine), (B). Cutting unit installed in the final process of the continuous mold.
12. Height stop unit
The main function of the height stop unit is to correctly determine the position of the dead center under the upper die, which takes the following two forms: (A). (A) The way of frequent contact during stamping process, (B) The way of contact during assembly. (B) The way of contacting only when assembling, but not when stamping. In addition, when the mold is being transported and stored, it is best to place a spacer between the upper and lower molds in order to prevent the upper and lower molds from coming into contact with each other. When accuracy is not necessary, the standard can be adjusted by screws. 1. Standard parts and specifications
The selection of standard specifications for molds should take the following matters into consideration: (A). When the content of the specification is not limited, it is better to use the highest level. (B). In principle, standard numbers are used. (C). If there is no such size in the standard parts of the mold, the closest one will be used for processing.
2. Punch design
The punch can be roughly divided into three parts according to its function: (A). (A) The cutting edge of the material to be processed (the cutting edge is irregularly shaped, square, round, etc.). (B). The part in contact with the punch fixing plate (the fixing part or shank part, whose cross-section shape can be irregular, square, round, etc.). (C). The part that connects the blade with the shank (the center part).
The design criteria for each part of the punch are (A). Cutting edge length, (B). The grinding direction of the cutting edge, (C). Punch fixing method and the shape of the shank and other aspects of the brief description.
3. Design of punch fixing plate
The thickness of the punch fixing plate is related to the size of the mold and load, generally 30~40% of the length of the punch, and the length of the punch guide should be higher than 1.5 times of the diameter of the punch
4. Design of guide pin (punch)
The diameter of the guide part of the guide pin (punch) is the gap between the guide holes of the material, its size and the protruding pressure hole. The gap between the diameter of the guide part of the pin and the hole of the material guide, its size and the amount of protruding pressure plate are designed according to the thickness of the material, and the apex shape of the pin is roughly divided into two kinds: A. Cannonball shape, B. Conical shape (push and pull shape).
(1). Cannonball shape is the most common form, and there are standardized parts available in the market.
(2). The conical shape has a certain angle, which is very suitable for high-speed stamping of small parts. The determining factors of the pushing and pulling angle are the stamping stroke, the material of the processed parts, the size of the guide hole, the processing speed, etc. When the pushing and pulling angle is large, it is easier to correct. It is easier to correct the position of the processed material when the pushing and pulling angle is large, but the length of the pushing and pulling part will become longer. Push and pull part and cylinder part of the connection should be smooth.
5. Design of concave mold
(1). Punching die design
The shape of the punching die should be designed to take into account the following key points: A. Die life and the shape of the escape angle, B. The shear angle of the die, C. The division of the die.
(A). Die life and the shape of the escape angle: This design is a very important matter, such as the design is not correct will cause damage to the punch, the clogging of the chip or floating, the occurrence of burrs and other stamping processing bad phenomena.
(B). The shear angle of concave die: In order to reduce the punching force when the shape is punched, the concave die can be designed with a shear angle, when the shear angle is large, the reduction of punching force is also large, but it is easy to cause the products to be distorted and deformed.
(C). Dividing the concave mold: The concave mold must be shaped and ground for finishing, because of its concave shape, it is not easy for the grinding tool to enter, so it must be divided.
(2). Bending die design
Bending die design, in order to prevent the occurrence of rebound and excessive bending phenomenon, U-shaped bending die shape for the combination of double R and straight part (30 degrees), preferably similar to the shape of the R. R shape should be polished after form grinding or NC discharge processing.
(3).
The design of the die
The shape of the corner part of the die and the shape of the escape angle are very important design matters, the shape and characteristics of the corner part and the escape angle are as follows: When the R angle of the die is large, it is easier to draw and process, but it also produces wrinkles on the surface of the products, and the thickness of the side wall of the products is greater than the thickness of the plate. For the occasion of drawing thick plate and ejection difficulty, the R value of concave mold should be small, about 1-2 times of the thickness of the plate. Generally, most of the drawing part of the upper cylinder and square cylinder drawing concave mold is made into a straight section, and for the purpose of preventing the occurrence of scorching, destroying the lubricating oil film, and reducing the ejector force, it is desirable to have a fleeing part (stage shape or push-out shape) designed under the straight section. Especially in the case of shrinkage processing, it is necessary to minimize this straight section.
6. Countermeasures against lateral pressure on the punch
The best ideal (i.e., zero lateral pressure) is for the punch to bear equal loads on the left and right sides of the punch during the stamping process, and when the punch bears lateral pressure, it will make the upper die and the lower die shift in the transverse direction, which will result in the part of the die gap becoming larger or smaller (uneven gap) and prevent the press from obtaining a good precision stamping process. Countermeasures against lateral pressure on the punch are as follows: (A). Change of processing direction, (B). Two rows should be used for single side processing (punching, bending, drawing, etc.), (C). Punch or concave mold equipped with side pressure block, the cutting edge of the side of the guide section (especially cut off and fracture processing).
7. Design of the backing plate
The main parts (punch, press plate, concave die) will be subjected to surface pressure after the stamping process, and it is advisable to use the backing plate (especially on the back of the punch and the concave die sleeve) when the punching force is higher than the surface pressure. The backing plate can be used in two ways: partially and fully.
Mold design software
Modern industrial development is very fast, basically the use of computer design and processing, its accuracy can be guaranteed at 0.002 ~ 0.01. Engage in mold design work has a boundless world. If you can use the computer to assist in the design, your opponents, invisible, behind you. Commonly used mold design software AUTOCAD Pro/E UG SW CImatron, mishiong and so on. Design is a key step in the production of molds, production of the initial link, control the entire process of mold production, so the design also has a great impact on the service life of the mold, design mainly from the following two aspects of the impact of the service life of the stamping die.
(1) the precision of the mold guiding mechanism. Accurate and reliable guidance, for reducing the wear and tear of mold working parts, to avoid convex, concave mold nibbling great impact, especially no gap and small gap blanking die, composite mold and multi-position progressive die is more effective. In order to improve the life of the mold, the design must be based on the nature of the process and the precision of the parts and other requirements, the correct choice of guiding form and determine the accuracy of the guiding mechanism.
(2) mold (convex, concave mold) edge geometric parameters. Convex, concave mold shape, fit clearance and fillet radius not only has a greater impact on the stamping parts forming, but also for the wear and tear of the mold and life also has a great impact. For example, the fit clearance of the die directly affects the quality of punched parts and the life of the die. Higher precision requirements, it is appropriate to choose a smaller gap value in the design; on the contrary, it is appropriate to increase the gap in order to improve the life of the mold.