This standard stipulates the principles for the determination of the process plan for precision blanking parts, the preparation of process procedures, the calculation method of process power and the selection of equipment. JB/T 6957-1993 Precision blanking process preparation principles JB/T6957-1993 Standard download and decompression password: www.bzxz.net

Machinery Industry Standards of the People's Republic of China
Precision blanking parts
Process preparation principles
1 Subject content and scope of application
JB/T 6957— 93
This standard stipulates the principles for determining the process plan of precision blanking (hereinafter referred to as fine blanking) parts, the preparation of process procedures, the calculation method of process power and the selection of equipment.
This standard is suitable for the process of metal strong edge pressing and fine blanking. 2 Reference standards
JB/Z272 precision blanking parts structure and processability
JB/Z280 precision blanking parts quality
JB/Z306 stamping process specification preparation method
3 Necessary conditions for preparation process
3.1 The production program of fine blanking parts should generally comply with the principle that the cost of a single piece is significantly lower than that of other processing methods. 3.2 The structure and craftsmanship of fine blanking parts should comply with the regulations of JB/Z272. 3.3 Fine blanking equipment should have the functions of blanking force, blank holder force and counter pressure, and should meet the rigidity and precision requirements required for fine blanking. 4. Determination of process plan
The process plan should be determined based on the principles of technical and economic systems. 4.1 Mold structure
4.1.1 For medium and small size fine blanking parts, the movable convex mode (the mold punch is movable relative to the mold base) mold structure is preferred. 4.1.2 For large or narrow fine-blanking parts with complex shapes and asymmetrical shapes, fine-blanking parts with many inner holes and thick plate fine-blanking parts with large stamping force, fixed convex mode should be used (the mold punch is opposite (fixed to the mold base) mold structure. 4.1.3 For fine blanking composite processes with flattening, countersunk holes, bending, etc. or when the strength of the convex and concave dies is too weak due to the use of composite dies, continuous dies should be used. Multi-process single-station molds can also be used when the batch size is not large. 4.2 Equipment
4.2.1 Fine blanking presses should be used first.
4.2.2 When there is no fine blanking press or the production batch is not large, a general hydraulic press or a mechanical press with additional edge holder and back pressure system devices can also be used.
4.3 Materials
4.3.1 Use roll material or long strip material first, and try to avoid using single piece of bad material. 4.3.2 The suitable material structure should be selected according to the quality grade requirements of fine blanking parts, and spheroidizing annealing should be avoided when preparing materials. 5 Preparation of process specifications
5.1 Contents of preparation of process specifications
The preparation of process specifications for fine blanking parts is centered on the fine blanking process, including material preparation, fine blanking, deburring and other subsequent processes. All processes are Chinese. The Ministry of Machinery Industry of the People's Republic of China approved the preparation of the
181
process on 1994-07-01 on July 27, 1993. bzxz.net
5.2 Commonly used process files are:
a.
b.
c.
d.
e.||tt| |Fineblanking parts pattern;
Fineblanking part process card,
Material preparation card,
Fineblanking die installation and adjustment rules:
Fineblanking process rules.
5.3 Process specification preparation method
JB/T 6957-93
Except for fine blanking parts drawings, the preparation of process specifications shall be in accordance with the provisions of JB/Z306. 5.4 Drawing of patterns
Fine blanking part drawings are the basis for compiling the fine blanking process, designing fine blanking molds, inspection tools, and formulating subsequent processing techniques. It is also the technical document for the acceptance of fine blanking parts. The drawing of drawings should comply with the following regulations: a.
b.
.
The structural workmanship should comply with the regulations of JB/T272; the quality labeling should comply with the regulations of JB/Z280; When the punching direction, fiber direction, shear surface hardness, etc. cannot be expressed or are inconvenient to express in the drawing, text explanations can be used. 5.5 Determination of layout
5.5.1 If the fine blanking parts do not have fiber direction requirements, the layout should minimize waste while ensuring the needs of the process and the quality of the shear surface of the workpiece.
5.5.2 When there are different requirements for the quality of the shear surface of each part of the shape, the part with the highest quality requirements should be placed on the feed side during layout so that the shear deformation area of ??this part is fully affected during fine blanking. constraints, as shown in Figure 1. M | The larger the overlap, the more beneficial it is to the shear surface quality of fine blanking parts, but at the same time it reduces the material utilization rate. Figure 2 shows the range of overlap values ??required for fine blanking parts. 182
0 group's
JIB/T 6957---93
Picture 2 Edge
10mm
Material thickness:
For materials with poor plasticity or when the quality of the contour shear surface of fine blanking parts is required, the upper limit is used. 5.7 Determination of subsequent processes
5.7.1 Fine blanking parts are high-precision blanking parts, most of which can be directly assembled and used. For a few, the accuracy cannot be reached or the fine blanking structure needs to be added for artistic needs. Fine blanking parts with remaining parts or pieces need to be processed later. 5.7.2 Deburring is a necessary subsequent fine-blanking process to complete fine-blanking parts. 5.7.3 The fine-blanking parts after surface protection treatment must not be lower than the dimensional accuracy requirements and shear surface roughness requirements of the fine-blanking parts pattern. 5.7.4 Try to avoid overall heat treatment of fine-blanking parts to prevent deformation. If it is necessary to use the method of small deformation: when the shear surface of the fine blanking part has hardness requirements, it is recommended to use steel with a high degree of deformation hardening, and use large plastic deformation in the fine blanking shear zone to meet the hardness requirements. 6 Calculation of fine blanking process force and selection of equipment 6.1 Calculation of process force
6.1.1 Calculation of blanking force P according to the empirical formula (1): P, --- 0. 91tor
武Medium:
The total length of each inner and outer shear periphery of fine blanking, mm; material thickness mm
Tensile strength of the material, MP.
Oe
6.1 .2 The blank holder force P is calculated according to the empirical formula (2): P--4lho,
Formula i: L....-The outer peripheral length of the fine blanking part.mm;h--The V-shaped toothed ring of the blank holder Height, mm;
--tensile strength of material, MPa
6.1.3 Counter pressure 1 is calculated according to the empirical formula (3): P=0.2P,
6.1.4 The total pressure P. is calculated according to the empirical formula (4): P.- P, f-.--- P
(2)
(3)
where: →- Blanking force, N;
JB/T 6957---93
P-.-V-shaped tooth ring edge holding pressure, N, generally take P-(0.30.5)P2. When there is no automatic pressure relief and pressure maintaining device in the edge holder system, take P-2.
P back pressure, N.
6.2 Selection of fine blanking equipment
6.2.1 Select fine blanking equipment and adjust each process power according to the above calculation data of fine blanking process power 6.2.2 While ensuring the quality of fine blanking parts Under this condition, try to use a small blank holder force and counter pressure. 6.2.3 The nominal pressure of fine blanking equipment must be greater than the total pressure P; when using an ordinary mechanical press as fine blanking equipment, its nominal pressure must be greater than 1.3F.
Additional notes:
This standard is proposed and administered by the Beijing Mechanical and Electrical Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Beijing Mechanical and Electrical Research Institute of the Ministry of Machinery Industry. The drafter of this standard is Zhang Xiaoguang.
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