Ⅰ. Obtain the necessary information
Analyze the stamping technology of the joint construction based on relevant data, then conduct process audit and standardization audit on the workpiece.
1) Obtain drawings of product parts with specific technical requirements.
Understand the shape, size and accuracy requirements of the workpiece. Find out the size (size and location) of the critical hole, the critical surface, the analysis and determination of the datum of the workpiece.
In fact, the process requirements for stamping parts are not absolute.
Especially in the current situation of the rapid development of stamping technology, according to the actual needs and possibilities of production, the comprehensive application of various stamping technologies, the reasonable selection of stamping methods, the correct formulation of the stamping process and the selection of mold structure, so that it not only meets the technical requirements of the product but also meets the conditions of the stamping process.
2) Collect process cards for workpiece processing.
In this way, it is possible to study the interrelationship between the front and back processes, the process requirements and the assembly relationships that must be mutually assured between the processes, etc.
3) Know the production batch of the workpiece.
The production of the parts plays a decisive role in the economy of the stamping process. To this end, it is necessary to determine the mold type, structure, material and other related matters according to the production batch of parts and the quality requirements of parts. We also analyze the economics of the tooling process and the reasonableness of the production of public buildings and draw the profile of the stamping step.
4) Determine the specifications and conditions of the workpiece raw materials (such as sheet, strip, coil, scrap, etc.), understand the nature and thickness of the material, determine whether to use less and no waste for sampling according to the manufacturability of the parts and initially determine the material specifications and accuracy grade.
On the premise of meeting the requirements of serviceability and stamping performance, cheap materials should be used as much as possible.
5) Analyze and design the requirements of the fiber direction and the direction of the burr in the process.
6) Analyze the technical capabilities and equipment conditions of mold making in the mold workshop and the situation of mold standard parts that can be used.
7) Familiar with the equipment information or situation of the stamping workshop.
8) Study and absorb the above information, then initially conceive the structural scheme of the mold.
If necessary, the established product design and the process can be modified, so that the product design, process and mold design as well as manufacturing can be better integrated between the three, in order to achieve more perfect results.
Ⅱ. Determine the process plan and mold structure type
The determination of the process solution is one of the most important aspects to be carried out after the process analysis of the stamped parts.
1) Based on the shape characteristics, dimensional accuracy and surface quality requirements of the workpiece, process analysis is performed to determine its main properties and to determine the nature of the basic processes, that is, drop material, punching, bending, deep-drawing, flanging and expansion.
A list of all the single processes required for stamping can generally be determined directly from the product part drawing requirements.
2) Determine the number of processes based on process calculations.
For stretched parts, the number of deep draws should also be calculated.
The bent part, the cut part should be processed once or several times according to its shape, size and accuracy requirements.
3) According to the deformation characteristics, dimensional accuracy and ease of operation of each processing, the order of the process is determined.
For example, using punch first and then bend, or bend first and then punch, etc.
4) According to the production batch, size, precision requirements, mold manufacturing level, equipment capacity, and other factors, the single process that has been initially arranged in order to the possible combination of processes.
For example, a compound stamping process, a continuous stamping process, etc. Generally, thick, low-precision, small-volume, large-size punches are suitable for single-process production, using simple dies.
Thin material, small size and a large number of punching parts are suitable for continuous production by step-in die.
For stamping parts with high positional accuracy, it is better to use the composite die for stamping.
After determining the nature, sequence and combination of processes, the stamping process is determined, and so does the structure of the dies for each process.
Ⅲ. Perform the necessary process calculations
1) Design the materials and calculate the rough dimensions.
2) Calculate the punching pressure (including punching and cutting force, bending force, deep drawing force, turning force, expansion force, and discharge force, pushing force, crimping force, etc.), and if necessary, also calculate the punching work and power.
3) Calculate the pressure center of the mold.
4) Calculate or estimate the thickness of each major part of the mold. Such as the thickness of the concave die, the die retaining plate, the pad and the free height of the discharge rubber or spring.
5) Determine the clearance of the convex and concave molds and calculate the dimensions of the working parts of convex and concave molds.
6) For the deepening process, it is necessary to determine the method of deepening (trimming or no trimming), calculate the number of times of deepening and the size of the semi-finished product in the intermediate process.
For some processes, such as continuous deepening of the strip, special process calculations are required.
Ⅳ. The overall design of the mold
Based on the above analysis and calculations, the general design of the mold structure is carried out (at this point, it is usually only necessary to outline the sketch) and the closing height of the mold is preliminarily calculated, the outline dimensions of the mold are outlined.
Ⅴ. Structural design of the main parts of the mold
1) Parts of the workpiece. Such as the design of the convex mold, concave mold, convex-concave mold and the choice of fixed form.
2) Position parts. There are many types of positioning devices commonly used in molds.
Such as adjustable positioning plate, fixed stopper pin, movable stopper pin and fixed side blade, etc., need to be selected and designed according to specific conditions.
In the continuous mode, it is also necessary to consider whether to use the initial stopper pin.
3) Unloading and pushing device. Such as the choice of rigidity or elasticity, the selection and calculation of springs and rubbers.
4) Guide parts. For example, choose guide column, guide sleeve guide or guide plate guide, choose middle guide column, side rear guide column or diagonal guide column, use sliding guide sleeve or ball guide sleeve with steel ball, etc.
5) Support and clamp parts and fasten parts. Such as the selection of the structure of the mold handle and the upper and lower mold base.
Ⅵ. Select stamping equipment.
The selection of stamping equipment is an important part of process design and mold design.
Reasonable selection of equipment has a major impact on the quality of the workpiece, the improvement of productivity, and safety during operation.
It also brings convenience to the design of the mold.
The choice of stamping type mainly depends on the process requirements and production volume.
The determination of stamping equipment specifications mainly depends on the process parameters and die structure size. For crank presses, the following requirements must be met the following requirements:
1) The nominal pressure of the press must be greater than the stamping process force, namely:
More precisely, it should be that the load curve of the stamping process must be under the permissible load curve of the press.
For deep-drawn parts, the deep-drawn work is also calculated.
2) The press loading height must meet the requirements of the mold closing height.
3) The stroke of the press should meet the requirements of the workpiece forming. For the press used in the drawing process, the stroke must be greater than 2 to 2.5 times the height of the workpiece in this process in order to place the blank and remove the workpiece.
4) The table size of the press must be larger than the shape of the mold base under the mold, and should leave the position of the fixed mold. Generally, each side is larger than 50 ~ 70mm. The size of the leak hole on the press table must be larger than the size of the workpiece (or scrap).
Ⅶ. Draw a general picture of the mold
The general diagrams of molds (including diagrams of parts and components) are drawn in strict accordance with drawing standards (GB/T4457~GB/T4460 and GB/T131-1993).
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 the drawing needs to form 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. Usually, half of them draw the situation before the stamping starts (when the press slider is in the upper stop position) and the rough is put in.
The other half draws the state of the punch after the punch is finished, the workpiece is formed (or separated), and the punch slider is in the lower stop position.
2) Top view.
Typically, one half draws a top view of the lower half and the other half draws a top view of the upper half.
The lower half of the top view is also sometimes fully drawn as needed.
3) Side view, elevation view and partial section view, etc. If necessary, draw a side view of the working position of the mold.
In some cases, the top right corner of the drawing is also used to draw a view of the upper part of the mold and a partial section.
4) Workpiece diagram.
The general artifact drawing is in the upper right corner. For work done by several sets of molds, it is necessary to draw a workpiece diagram for this process in addition to the workpiece diagram for the previous process.
5) Sample diagram.
For the progressive die, it is necessary to draw the layout, the sequence of the process and the stamping content of each work step.
It should also indicate the step spacing, edge value and strip size.
The layout of the die is marked with the layout method, the strip size and the size of the overlay value.
6) List the parts list, indicating the material and quantity. Any standard parts are to be selected for the specification.
7) Technical requirements and description.
Technical requirements include punching pressure, selected equipment type, overall mold tolerance and assembly, installation and commissioning, mold closing height, mold clearance and other requirements.
Ⅷ. Draw non-standard parts
All dimensions, tolerances and fits, shape and position tolerances, surface roughness, materials used and their heat treatment requirements, and other technical requirements should be indicated on the parts drawing.
Ⅸ. Filling out tooling record cards and preparing stamping process documentation
For small batch production, the process route detail table should be filled in; for large batch production, the process card should be developed for each part.