1: Product introduction
1 Conventional product introduction process for precision stamping and grinding tools
1.1 Product drawing → Processing drawing → Layout drawing → Structural drawing → Assembly drawing → Mold drawing
1.2 Continuous mold layout drawings and structural drawings must be reviewed
1.3 Single punch mold layout drawings and structural drawings must be reviewed
1.3 Mold drawings must be reviewed and signed to take effect, and the drawing specifications are clear
2 Sample control process
Provide samples on site → self-inspection → quality control department inspection → test report → test report confirmation → engineering department → customer
2: Mold design
1.Mold design process
(1) Mold design flow chart
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(2) This is the basic process of mold design. Under normal circumstances, the steps of this process should be followed to plan and implement the design work. For the design of some special products, based on this process, it can be changed appropriately according to the actual situation.
2. Drawing specifications for product drawings, expansion drawings, processing (process) drawings, and strip drawings
(1) Product drawings Product drawings or products (samples) for mold opening are provided by the customer and the document control center. Because the product drawings come from various customers, the specifications are different, and there are unclear drawings, imperfect markings, confusing dimensions or testing standards, or errors caused by human negligence. Therefore, you should draw the product drawings for your own use based on the original drawings and on the premise of being loyal to the original design. For process problems in the customer's drawings, communicate with the customer's engineers in a timely manner. If the process or structural requirements are difficult to meet, you can negotiate with the other party's engineers and solve them by reducing the process requirements, changing the product structure, or adding process auxiliary means. The customer's original drawings shall not be altered and shall be kept as they are. For samples provided by customers, various methods are used to accurately measure the sample dimensions and create product drawings. Customer samples must be properly stored. The product drawings produced must have accurate data, clear requirements, complete dimensions, reasonable tolerances, and easy inspection.
(2) Processing drawings: After confirming the product drawings, start formulating the processing drawings. When formulating processing drawings, you should pay attention to the following points:
point:
A: The value of product size is divided into two situations: punching and blanking. The punching size is determined by the punch, and the blanking size is determined by the die.
B: The value of product tolerance is based on the product drawing. If the tolerance is marked on the product drawing, it shall be implemented according to the drawing. If the tolerance is not marked on the product drawing, the tolerance used by the customer shall prevail.
Refer to Figure 1-1 for the direction of tolerance values. For the size that will become larger after punching, the size of the processing drawing is 2/3 of its lower deviation. For the size that will become smaller after punching, the size of the processing drawing is 2/3 of its upper deviation. For dimensions such as hole center distance and hole edge distance that remain basically unchanged after punching, the values are based on the intermediate tolerance.
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C: Consider the deformation trend of the product during the molding process, and take some pre-remedial measures to address these deformations.
(3) Expanded view The expanded view is based on the processing drawing, and the bending lengths of each section are marked in order to facilitate inspection.
A: Expand the calculation principle. During the bending process of the sheet, the outer layer is subject to tensile stress, and the inner layer is subject to compressive stress. There is a transition layer between tension and compression that is neither tensile nor compressive - the neutral layer. The neutral layer is The length during the bending process remains the same as before bending, so the neutral layer is the basis for calculating the unfolded length of the bent piece. The neutral layer and the middle layer of the sheet thickness are different concepts. The position of the neutral layer is related to the degree of deformation. When the bending radius is large and the bending angle is small, the degree of deformation is small, and the neutral layer is located close to the center of the sheet thickness; when the bending radius becomes smaller and the bending angle increases , the degree of deformation increases, and the position of the neutral layer gradually moves toward the inside of the bending center. The distance from the neutral layer to the inside of the sheet is represented by λ.
B: Expansion calculation method Basic formula: Product expansion length = In-material + In-material + Compensation amount
a: R angle expansion. The expansion principle is based on the constant length of the neutral layer material.
R in = R in + Kt
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(4) Material strip diagram (process diagram, layout diagram)
(1) Decide whether to use a continuous mold or a single-process mold based on customer requirements, product accuracy, product output, mold life, process characteristics, etc.
(1) The classification of mold accuracy levels is determined based on product required accuracy, total mold production volume, mold production speed, etc. Precision continuous molds are divided into four grades: A, B, C, and D. Precision single-process molds are divided into three grades: A, B, and C. The grade classification standards are shown in the table below:
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(1) The arrangement method of blanking parts on the strip is called layout. Each workpiece will have multiple layout plans.
The layout methods include straight row, single row arrangement, multi-row arrangement, diagonal arrangement, opposite-to-head straight arrangement, opposite-to-head diagonal arrangement, etc.
Layout work is simple, but important. There are four principles for layout:
a: Improve material utilization. Material utilization accounts for more than 60% of the total cost of stamping parts and is a very important economic indicator. The waste generated during the blanking process is divided into two types: structural waste and process waste. When laying out samples, process waste should be minimized and material utilization should be improved.
b: It is easy and safe to operate and reduces the labor intensity of workers. For single-process molds, the material should be turned less during the punching process. When the material utilization rate is the same or similar, the strip should be as wide as possible and the feed distance should be as small as possible. layout plan.
c: Make the mold structure simple and the mold life longer.
d: The layout should ensure the quality of the punched parts. This is explained in detail in the next section.
(1) For precision continuous molds, before determining the layout drawing, make a punch superposition drawing. The purpose of making this picture is to ensure that all waste materials are flushed out and a complete product is obtained. First of all, it is necessary to determine the raw edge surface of the product, the requirements for the direction of the product material grain, the step distance, the width of the strip, the datum plane of the product, the reasonable edge overlap and the feeding direction. The order of punches, the order of bending, the location of positioning holes and edges, etc. should be taken into consideration.
The shape of the punch should try to achieve the following points:
a: Try to avoid rectangular punches, because rectangular punches are prone to scrapping.
b: The punch should avoid excessively long cantilevers and slots. Because the cantilever will affect the strength of the punch. Slots will affect the strength of the die. Try to avoid sharp corners when punching.
c; The punch should have an anti-removal structure, and the processing technology should be taken into consideration. Grinders and wire cutting should be used as much as possible to reduce electrical discharge processing.
d: There will be an interface at the connection between the two punches. To ensure smooth blanking, try to reduce the size of the punch interface position on the product. For some products, the size, position and shape of the interface must be discussed with the customer. Discuss and formulate together.
(1) Distribute the punches and forming processes in the punch superposition diagram at appropriate positions in the mold, which is the layout diagram.
Comprehensive consideration based on drawings and process requirements. Pay attention to the following points in the layout diagram:
a: Holes with high relative position tolerance requirements or holes that determine the centerline position must be punched out in the same step.
b: If there are punching or other processes on the segment, and the position accuracy of these processes is high, it is recommended to punch or otherwise form the segment after the segment, so as to avoid affecting the size due to inaccurate expansion of the segment.
c: If there are symmetrical bends in the product, it is recommended that the symmetrical bends be formed in the same step. It can balance the force. If the curved side of the product is long, in order to balance the force, it can be designed to be a process balance bend, and the process bend will be washed away after bending.
d: Deep drawing or other processes in the product may affect the nearby dimensions during forming. These processes can be shaped in advance.
Overlap refers to the remaining material between adjacent blanking parts, or the remaining material between the blanking part and the edge of the strip. The size of the overlap is related to the size and complexity of the product. If the product is large or the curved edge is long, the overlap value should be larger.
(2) Layout line type, color, and layer settings:
Material Tape Layer MATER Layer Color No. 8 Gray Solid Line
Punching, trimming, blanking, half-cutting, tearing, etc. are layer 1. Color No. 1 red solid line
Printing, embossing, chamfering, burring, etc. 2 layers Color No. 2 yellow solid line
Bending, forming, flanging, tooth extraction, etc. 3 layers Color No. 3 yellow The inner edge of the lower fold is a dotted line
Fold upward into a solid line.
The label and description are 4 layers, color No. 4, solid line
After the layout drawings are reviewed and collectively reviewed and confirmed to be correct, the next work process will be entered.
3. Drawing of the general drawing of the mold
(1) After the layout drawing is determined, start drawing the overall mold drawing.
a: Layer settings in the overall map:
MATER Layout 4 Annotation
UP (upper mold base) UB (upper backing plate)
PH (Male Plywood) PUNCH
PPS (stop plate) PS (stripping plate)
PS_P Take off the board and insert it into the sub-DIE (lower template)
DIE_P Lower mold insertion
LB (lower plate) LP (lower mold base)
B2 (lower block) B1 (lower support plate)
b: Instructions on thread type and thread color:
Punch and insert outline outline No. 2 yellow Line cutting hole No. 1 red
Milling contour No. 40 brown
Electric discharge machining line No. 40 brown Drill processing No. 40 brown
Template shape No. 7 white
The thread color used should always be consistent. The visible part of the graph is a solid line, and the invisible part is a dotted line.
(2) Mold structure diagram
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(3) Selection of precision continuous mold structure. Determine the mold grade based on product accuracy and total production volume. take mold
Based on the grade, the mold structure is selected. The picture above shows the continuous mode structure.
(4) Mold template standards
☆ If the length of the template exceeds 500MM, it needs to be divided into boards, and a connecting buckle must be added between the two boards.
☆ According to the material thickness of the punched product and the length of the mold, appropriately increase the thickness of the upper mold base plate and the lower mold base plate
☆ After vacuum heat treatment of the stripper plate and lower template, among them, A-level precision mold manufacturing, stripping
The plate and lower formwork need to be ultra-deep processed. For B-level precision mold manufacturing, the stripper plate and lower template need to be
Cryogenic treatment.
☆ The upper and lower mold base plates need to be tapped with lifting eye screw holes, M16-M24 etc. depending on the size of the mold.
☆ There must be screw holes for installing mold safety inspection tools on the sides of the stripper plate and lower template.
☆ For large molds, the placement of the feet should take into account the convenience of mold transportation. Reserve a forklift space.
☆ For molds with templates smaller than 300MM, the outer guide pillar should be 28MM in diameter. Template size is greater than 300MM
For the mold, select the outer guide pillar assembly according to the actual situation.
☆ For molds with outer guide posts, when placing the outer guide posts, consideration must be given to preventing foolproofing when closing the mold. Mold without outer guide pillar
Tools, also adjust the position of the inner guide pillar appropriately to avoid backlash when closing the mold.
☆ On all templates, reference holes for process processing must be left. Specifically, when rough machining, at the appropriate position of the template, fine
Ream a hole with a diameter of 6MM for subsequent processing as a positioning reference.
☆ Determine the size and quantity of template fixing screws. Refer to the table below:
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4. Molding step structure design
After the mold structure and assembly drawings are completed, the structural design of the molding step begins. That is, draw the mold structure of the molding steps in detail
structure, while verifying the rationality and reliability of the forming steps.
(1) The structural design of the molding step must first consider the rebound of the product after molding. Rebound takes the form of bending
There are two aspects: the radius increases and the angle of the bending part increases. Factors that affect springback include mechanical properties of materials, relative bending
The influence of bending radius, bending angle, bending method, mold gap, workpiece shape and non-deformation zone, etc.
Various factors influence each other during bending.
Springback is calculated as follows:
When R≤5, depending on the material thickness and material, the following table is provided as a reference for the springback amount.
Depending on the hardness of the material, the greater the hardness, the larger the value will be.
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When R≥5, the rebound angle is calculated as follows:
(2) Structural design of commonly used bending forming steps
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The above scheme shown on the right is a reference scheme and is not generally used.
5. Stamping materials and mold standard parts
(1) The following are the brands and basic data of commonly used metal materials
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Note: 1. The minimum value of the initial gap is equivalent to the nominal value of the gap.
The maximum value of the initial gap is a value increased by taking into account the manufacturing tolerances of the punch and the die.
(3) Selection of standard parts
The purchasing department is responsible for purchasing the mold standard parts used in our precision molds. The design engineer is responsible for the procurement of standard parts
Purchase order. For the model number of standard parts, please refer to the standard part model number of Panqi Company.
5. Specifications for drawing and issuing mold drawings
(1) Drawing of mold drawing
a: After the overall drawing and molding step structure design are completed, draw template drawings, mold parts drawings, and standard parts drawings.
b: The drawing of mold drawings must strictly comply with the regulations of layer, line type, and line color.
c: The template drawing must carefully indicate the template material, template thickness, heat treatment process and required hardness, and template accuracy requirements.
and other technical requirements.
d: The parts drawing must carefully indicate the part material, part size, number of parts, part heat treatment process and required hardness.
Information such as degree, part processing method and so on.
e: If the outsourced mold parts are standard parts, write the purchase application form according to the standard part model. If it is not a standard part, please provide the details.
Parts drawings shall be provided to the supplier.
f: All drawings must be clear, clear in size, accurate in expression, and neatly arranged.
g: Mold drawings use a unified frame.
Specifications for issuing mold drawings
a: All mold drawings can be issued only after being reviewed and signed by superiors.
b: A complete set of mold drawings including template drawings, parts drawings, standard parts drawings, layout drawings, assembly diagrams, and assembly drawings.
Together with schematic diagrams and product drawings, the entire set of drawings is generally issued together. If the mold manufacturing cycle is short, you can place the
Send sample pictures. Mold material ordering orders and mold standard parts ordering orders are issued with the mold drawings or in advance.
three. Mold process control
1. Follow-up of mold manufacturing process
After the mold drawings are issued to the mold manufacturing department, designers should follow up on the mold manufacturing progress at any time. Keep abreast of various situations that occur during the processing process, identify problems, and coordinate with the manufacturing department to solve them in a timely manner.
2. Mold assembly technical requirements
a: During assembly, it should be ensured that the gap between the convex and concave molds is uniform and the matching gap meets the design requirements.
b: The joint surfaces between the inserts, the template and the inserts are close to each other.
c: The height of the die blade for blanking and punching must be manufactured according to the design requirements to ensure that the leakage hole is unobstructed.
d: All movable parts of the die should move smoothly without stagnation. When the slider and wedge move on the fixed sliding surface, their minimum contact area should be no less than two-quarters of their area.
e: The screws and pins used for fastening must not be loose, and ensure that the end faces of the screws and pins do not protrude from the plane of the upper and lower molds
f: The depth of the counterbore of each unloading screw should be consistent.
g: The length of each unloading screw and ejector rod should be consistent
h: The verticality of the punch must be within the allowable range of the gap between the punch and the die
j: The assembly of the punch mold must comply with the mold assembly drawing and technical conditions.
Four. Formulation of product process documents
After the mold manufacturing is completed, product process documents are formulated. Product process documents guide production
first-hand information. Want to pack
Contains the following information: product model, material size, production auxiliary materials, production process, product gross weight, production equipment
And equipment model, inspection requirements, packaging specifications, etc.
For the formulation of specific process files, please refer to the process file formulation standards.
five. appendix
1. Density of commonly used materials
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2. Stamping oil selection table
