1. Obtain the necessary information
According to the relevant data, the co-construction stamping process is analyzed, and the workpiece is subject to process audit and standardization audit.
1) Obtain product parts drawings indicating specific technical requirements. Understand the shape, size and accuracy requirements of the workpiece. The dimensions (size and location) of critical holes, critical surfaces, analyze and determine the datum of the workpiece.
In fact, the technological requirements of stamping parts are not absolute. Especially in the current rapid development of stamping technology, according to the actual needs and possibilities of production, comprehensive application of various stamping technologies, reasonable selection of stamping methods, correct stamping process formulation and die structure selection, so as to meet the technical requirements of the product. requirements, and meet the conditions of the stamping process.
2) Collect process cards for workpiece processing. From this, the relationship between the previous and subsequent processes and the processing technology requirements and assembly relationships that must be guaranteed to each other between the processes can be studied.
3) Understand the production batch of the workpiece. The production of parts plays a decisive role in the economy of stamping processing. For this reason, it is necessary to determine the type, structure, material and other related matters of the mold according to the production batch of the parts and the quality requirements of the parts, and then analyze the mold processing technology. The economy and the rationality of public construction production, describe the outline of the stamping process.
4) Determine the specifications and raw materials of the workpiece raw materials (such as sheets, strips, coils, scraps, etc.), understand the nature and thickness of the materials, and determine whether to take samples with little or no waste according to the craftsmanship of the parts, and make a preliminary determination Specifications and accuracy grades of materials.
On the premise of meeting the requirements of performance and stamping performance, cheap materials should be used as much as possible.
5) Analyze the design and process requirements for the fiber direction of the material and the direction of the burr.
6) Analyze the technical ability and equipment conditions of the tool (mold) workshop to manufacture molds and the conditions of the mold standard parts that can be used.
7) Familiar with the equipment information or situation of the stamping workshop.
8) Study and digest the above information, and initially conceive the structural scheme of the mold. When necessary, it is possible to propose amendments to the established product design and process, so that the product design, process and mold design and manufacturing can be better combined to achieve more perfect results.
2. Determine the process plan and mold structure type
The determination of the process plan is one of the most important links that should be carried out after the process analysis of stamping parts. it includes:
- 1) According to the shape characteristics, dimensional accuracy and surface quality requirements of the workpiece, carry out process analysis, determine its main attributes, and determine the nature of the basic process. That is, the basic processes such as blanking, punching, bending, deep drawing, flanging and bulging. List all the single and all processes required for stamping, and the general situation can be directly determined from the product part drawing requirements.
- 2) According to the process calculation, determine the number of processes. For drawn parts, the number of deep drawing should also be calculated. The bending parts and blanking parts should also be processed once or several times according to their shape, size and accuracy requirements.
- 3) According to the deformation characteristics of each processing, the requirements of dimensional accuracy and the convenience of the required operation, determine the sequence of the process arrangement. For example, punching first and then bending, or first bending and then punching, etc.
- 4) According to various factors such as production batch, size, precision requirements, mold manufacturing level, equipment capacity, etc., the single processes that have been initially arranged in sequence are combined into possible processes. Such as composite stamping process, continuous stamping process, etc. Generally, punching parts of thick material, low precision, small batch and large size should be produced in a single process, and simple die should be used; punching parts of thin material, small size and large batch should be continuously produced by progressive die; High stamping parts should be stamped with a composite die.
After determining the nature, sequence and combination of the processes, the stamping process plan is determined. That is to say, it determines the structure of each process mold.
3. Carry out the necessary process calculations
- Layout of design materials and calculation of blank size.
- Calculate the punching force (including punching force, bending force, deep drawing force, flanging force, bulging force, and unloading force, pushing force, blank holder force, etc.), and if necessary, also calculate the punching work and power .
- Calculate the pressure center of the mold.
- Calculate or estimate the thickness of each main part of the mold. Such as the thickness of the die, the punch fixing plate, the backing plate, and the free height of the unloading rubber or spring.
- Determine the gap between the convex and concave dies, and calculate the dimensions of the working parts of the convex and concave dies.
- For the deep drawing process, it is necessary to decide the method of deep drawing (edge blanking or no blank blanking), and calculate the number of times of drawing and the size of the semi-finished product in the intermediate process.
For some processes, such as continuous drawing of strips, special process calculations are required.
4. the overall design of the mold
On the basis of the above analysis and calculation, the overall design of the mold structure is carried out (generally, only the sketch is required at this time), and the closed height of the mold is preliminarily calculated, and the overall dimensions of the mold are roughly determined.
5. Structural design of the main parts of the mold
- 1) Parts of the workpiece. Such as the design of punch, die, punch and die and other structural types and the choice of fixed form.
- 2) Position the part. There are many types of positioning devices commonly used in molds. Such as adjustable positioning plate, fixed stopper pin, movable stopper pin and fixed-distance side edge, etc., need to be selected and designed according to the specific situation.In the continuous mold, it is also necessary to consider whether to use the initial stop pin.
- 3) Unloading and pushing device. Such as the choice of rigidity or elasticity, the selection and calculation of springs and rubbers, etc.
- 4) Guide parts. Such as the choice of guide post, guide sleeve guide or guide plate guide, the choice of the middle guide post, the side rear guide post or the diagonal guide post, whether to use a sliding guide sleeve or a ball guide sleeve with steel balls, etc.
- 5) Support and clamp parts and fasten parts. Such as the selection of the structure type of the mold handle, the upper and lower mold bases, etc.
6.selected stamping equipment
The selection of stamping equipment is an important part of process design and die design. Reasonable selection of equipment has a significant impact on the guarantee of workpiece quality, the improvement of productivity, and the safety of operation, and also brings convenience to the design of molds.
The selection of stamping type mainly depends on process requirements and production batch.
The determination of the specifications of the stamping equipment mainly depends on the process parameters and the size of the die structure. For crank presses, the following requirements must be met:
1) The nominal pressure of the press must be greater than the process force of the stamping. which is
More precisely, it should be that the load curve of the stamping process must be below the allowable load curve of the press.
For deep drawing parts, the drawing work should also be calculated.
2) The mold height of the press must meet the requirements of the mold closing height.
3) The stroke of the press should meet the requirements of workpiece forming. For the press used in the deep drawing process, its stroke must be greater than 2 to 2.5 times the height of the workpiece in the process, so that the blank can be put in and the workpiece can be taken out.
4) The table size of the press must be larger than the overall size of the lower die seat of the mold, and there must be a place for fixing the mold. Generally, each side is larger than 50~70mm. The size of the leak on the press table must be larger than the size of the workpiece (or scrap).
7. Draw the general drawing of the mold
The drawing of the general drawing of the mold (including the drawing of the parts and workpieces) is strictly in accordance with the drawing standards . At the same time, in actual production, combined with the working characteristics of the mold and the needs of installation and adjustment, the layout of its drawings forms a certain habit.
The general drawing of the mold includes:
- 1) Main view. Draw a cross-sectional view of the mold in the working position. In general, half of them are drawn before the stamping starts (when the punch slider is at the top dead center); the other half is drawn after the stamping is finished, the workpiece has been formed (or separated), and the punch slider is at the bottom dead center. status of the location.
- 2) Top view. Usually half of the top view is drawn, and the other half is drawn with the top view of the upper half. The bottom half of the top view is also drawn completely as needed.
- 3) Side view, bottom view and partial section, etc. If necessary, draw a side view of the working position of the mold. Sometimes the bottom view and partial section of the upper half of the mold are also drawn in the upper right corner of the pattern.
- 4) Workpiece diagram. The general workpiece picture is in the upper right corner. For the work completed by several sets of molds, in addition to drawing the workpiece map of this process, it is also necessary to draw the workpiece map of the previous process.
- 5) layout drawing. For the progressive die, it is necessary to draw the layout method, the sequence of process arrangement and the stamping content completed by each step; the step spacing, edge value and strip size should be marked. The layout drawing of the blanking die needs to indicate the layout method, strip size and edge value.
- 6) List the parts list, indicating the material and quantity. All standard parts must be selected specifications.
- 7) Technical requirements and descriptions. Technical requirements include punching force, selected equipment model, overall mold tolerance and assembly, installation and debugging, mold closing height, mold clearance and other requirements.
8. draw the parts diagram of each non-standard part
All dimensions, tolerances and fits, geometric tolerances, surface roughness, materials used and their heat treatment requirements, as well as other technical requirements should be indicated on the part drawing.
9.fill in the mold record card and write stamping process documents
For small batch production, a detailed process route table should be filled in; while in mass production, a process card and process card should be formulated for each part.