JB/T 6234-1992 Stamping process guide for electric tool stamping parts
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Mechanical Industry Standard of the People's Republic of China
Stamping Process Guidelines for Electric Tool Stamping PartsWww.bzxZ.net
1 Subject Content and Scope of Application
T6234—1992
This standard specifies the equipment selection, stamping die requirements, layout and overlap, processability of stamping parts, precision of stamping parts, die installation, and safe operation of punch presses for cold stamping parts of electric tools. This standard applies to the stamping process for making stamping parts used in electric tools. 2 Materials for cold stamping parts
2.1 Mechanical properties requirements for materials for stamping parts 2.1.1 The mechanical properties of the material must not only meet the strength and rigidity requirements required for electric tool parts. It must also meet the cold stamping process requirements, and try to avoid using too thick materials. 2.1.2 Use materials with high plasticity as much as possible. Materials that are too hard will affect the service life of the mold. Highly elastic materials are extremely unfavorable to the stamping process. The rebound generated after bending will bring difficulties in forming and affect the precision of stamping parts. 2.1.3 Good plasticity of materials is the key to stamping. For bending parts with complex shapes, the materials of stretching parts should have good plasticity and cold hardness, otherwise it will be difficult to form.
2.1.4 There are high requirements for the surface state and thickness error of the material. If there are defects such as slag, rust spots, and oxide film on the surface of the material, the mold will wear faster. Excessive material thickness will bring difficulties to forming and even cause damage to the mold. 2.2 Selection of materials for cold stamping parts
2.2.1 Ferrous metal materials
2.2.1.1 Common grades of silicon steel plates for electrical use are 0R490-50; 0R255-35; 0R290-50, etc. 2.2.1.2 Common grades of ordinary carbon steel plates and high-quality carbon steel plates are Q235A (A3); 08; 08F; 20; 30; 45; 65Mn, etc. 2.2.2 Common grades of non-ferrous metal materials include H62; H68; pure copper T2; silver-copper alloy; tin bronze, etc. 2.2.3
Common insulation and non-metallic materials include phenolic laminates; epoxy phenolic glass cloth boards; mica boards; wool felt, red steel paperboard, etc. 3. Selection of presses
The following factors should be considered when selecting a press. 3.1 Tonnage of the press
3.1.1 The determination of the tonnage of the press during punching is shown in formula (1): P ≥ 1.3P,
- tonnage of the press, kN;
Wherein: P -
P, punching force, N;
3.1.2 Determination of the tonnage of the press during bending
3.1.2.1 The determination of the tonnage of the press during free bending is shown in formula (2): P ≥ 1.5P
Wherein: P - tonnage of the press, kN;
- uncorrected bending force of the material at the end of the punching stroke, N. P
3.1.2.2 Determination of press tonnage for correction bending, see formula (3): Approved by the Ministry of Machinery and Electronics Industry on June 16, 1992, and implemented on January 1, 1993
Where: P press tonnage, kN;
P: correction force, N.
JB/T6234-1992
3.1.3 Determination of press tonnage for stretching, see formula (4): Pz≥P+P
Where: P2—press tonnage, kN;
P.—pressing force, N;
—stretching force, N.
3.2 The size of the press work table must ensure that the mold can be installed correctly and the leaking workpiece or waste can pass through the table hole smoothly. (3)
3.3 The stroke of the press slide must reach the required height or depth of the stamped workpiece and be able to remove the workpiece. For bending and stretching workpieces, the working stroke must be more than twice the height of the workpiece. 3.4 The maximum closing height of the press must be greater than the closing height of the mold. 3.5 The number of stamping times per minute of the slide should be considered based on productivity and material deformation requirements. 4 Requirements for cold stamping dies
4.1 The cold stamping die should have sufficient hardness and wear resistance. The hardness of the working part of the die should reach HRC58 or above after heat treatment to ensure the required accuracy and life of the die.
4.2 The cold stamping die should have a certain strength and rigidity so that it can withstand a large stamping force during operation. 4.3 The maximum allowable value of the surface roughness parameter Ra of the working part of the cold stamping die (referring to the cutting edge, the wall of the convex and concave die holes, and the cavity) is 0.8μm to increase the service life of the die.
4.4 The cold stamping die should have a compact and reasonable structure, reliable installation, easy operation, and safe use. 4.5 The closing height of the die should be less than the maximum closing height of the punch press used. 4.6 The clearance at the cutting edge of the punching die and the clearance at the working part of the forming die should be uniform. The determination of the clearance size should fully consider the elastic recovery of the material (referring to high-precision punching parts) and the wear of the die to increase the service life of the die. 4.7
The die handle should be consistent with the diameter and depth of the slider die handle hole. The materials of the main parts of the cold stamping die are recommended to be selected according to Table 1. Table 1 Materials of main parts of the mold
Mold type
Drawing mold
5 Layout and overlap
5.1 Layout
Part name
Punches and dies with simple shapes
Punches, dies and blocks with complex shapes
Punches, dies and blocks of silicon steel sheet punching dies with low precision requirements
Punches, dies with high precision requirements, punches, dies and blocks with complex shapes Punches and dies for shallow drawing parts
Punches and dies for deep drawing parts and punches and dies with high precision requirements The economic degree of layout is expressed by the material utilization rate K, see (5): K=
Selected materials
T8A, T10A
9SiCr, Cr12, CrWMn, Cr12MoV
Cr12, Cr12MoV, GCr15, YG15
T8A, T10A
CrWMn, Cr12, Cr12MoV
T8A, T10A
Cr12, Cr12MoV, YG15
In the formula: K
Material utilization rate
Number of punchings produced on the strip
a—area of each punching, mm2
A. Strip area, mm?
JB/T62341992
The length and width of sheet or coil material have certain specifications, so the rational use of the whole piece of material must be considered when arranging. The economic use of materials is also closely related to the shape of the parts. Commonly used layout methods: straight arrangement, single row arrangement, multi-row arrangement, oblique arrangement, end-to-end straight arrangement, end-to-end oblique arrangement, no waste arrangement, etc. 5.2 Overlap
The excess material between adjacent blanking parts or the excess material between the blanking parts and the edge of the strip material in the layout is called overlap. The overlap is used to prevent the punching out of incomplete waste when the feeding is deviated. The overlap cannot be too large, which wastes raw materials, nor too small. Too small overlap is not rigid enough, and there is a disadvantage of entering the die with the punch, which is easy to damage the cutting edge. For carbon steel plates and silicon steel plates, the overlap value is recommended to be selected from Table 2. Table 2 Overlap values
Round parts and corners with r>21
Material thickness
Area between workpieces;
0.25 or less
3.0～3.5
Side a
Note: For brass and copper, the values in the table are 1.1～1.2 times. 0
Rectangular parts with side length <50
Area between workpieces:
Side a
Rectangular parts with side length I>50
Or four corners r<2t
Area between workpieces:
For non-metallic materials (red steel board, phenolic glass cloth board, mica board, wool blanket, etc.), the values in the table are 1.5～2 times. 6 Blanking parts
6.1 Processability of blanking parts
6.1.1 The shape of blanking parts should be simple, symmetrical and easy to use, with less waste blanking. 32
Side a
JB/T 6234-1992
The corners of the outer shape or inner angle of the blanking parts should avoid sharp angles and have appropriate rounded corners. The size of the rounded corners is recommended to be selected according to Table 3. Table 3 Fillet radius
90°a=90
a>90°
R≥0.25t
Note: 1 is the material thickness. When <1mm, it is calculated as 1mm. Material
6.1.3 The width of the protruding or concave part of the blanking part should not be too small, and avoid overly long cantilevers and narrow slots (Figure 1). When the blanking part is made of medium carbon steel, 6 ≥ 2t; when the blanking part is made of brass or copper, the material thickness t < 1mm is calculated as t = 1mm. When the blanking part is made of low carbon steel, 6 ≥ 1.5t:
Figure 1 Minimum width of blanking part
6.1.4 The minimum punching size of the blanking part is related to the shape of the hole, the mechanical properties of the material and the material thickness. The minimum punching size is recommended to be selected from Table 4.
Minimum punching size
Mild steel and brass
Phenolic laminated cloth (paper) board
Shape (diameter)
Note: 1 is the material thickness. When l<1mm, it is calculated as =1mm. Square hole
Rectangle (short side)
6.1.5 The distances a and b between holes and between holes and edges of blanking parts (Figure 2) are limited by the strength of the mold and the quality of the blanking parts. Their values cannot be too small. It is advisable to take a≥2t and b≥3t. If necessary, b can be 1~1.5t, but this will reduce the service life of the mold and increase the complexity of the mold.
JB/T6234—1992
Figure 2 Hole side moment and hole spacing of blanking parts
Note: t is material thickness. When (<1mm, it is calculated as (=1mm. 6.2 Precision of blanking parts
The precision that can be achieved during blanking can be divided into two categories: economic grade and precision grade. Generally, the economic grade blanking precision is used as much as possible, which is conducive to improving the service life of the mold and reducing the manufacturing cost. 6.2.1 The precision level of the economic grade is IT13~IT14 The precision level of the precision grade is IT1G～IT11 The limit of the unindicated tolerance size is IT14～IT15 6.2.2 The limit deviation of the unindicated tolerance size The limit deviation of the oriented hole is (ten)
The limit deviation of the shaft is (one)
The length and depth are IT||tt| |6.3 Burrs of stamping parts
The size of the burrs of stamping parts is determined by measuring the burr height value, and the measurement methods include visual inspection, micrometer, optical instrument measurement, etc. The allowable burr height of stamping parts should not be greater than the value recommended in Table 5. Table 5 Burrs of stamping parts
Material thickness
0.65~0.95
Note: "Class -
For stamping parts with extra-high requirements.
Class 1 is used for stamping parts with higher requirements.
Class I - For stamping parts with general requirements.
Class N - For stamping parts with lower requirements.
7 Bending parts
Processability of bending parts
JB/T6234-1992
7.1.1 The fillet radius of the bent part should not be less than the minimum bending half radius. diameter to avoid cracks, but it should not be too large, because if the bending radius is too large, the springback will be large and the bending accuracy will be difficult to ensure.
The recommended value of the minimum bending radius is shown in Table 6.
Minimum bending radius
Hard steel (low plasticity)
Non-ferrous metals
Note: t-
is the material thickness, mm.
7.1.2 The bending length of the bent part should not be too short, and its value h>R+2t (Figure 3) R
Figure 3 The bending length of the bent part
Bending fillet radius
R≥2t
7.1.3 The bending line should not be located at the sudden change of part size to avoid tearing. If it is necessary to bend at the sudden change of width, the process holes or process grooves should be punched in advance.
7.1.4 When bending a rough part with holes, if If the hole is too close to the bending area, the hole will be deformed during bending (Figure 4). The reasonable position should be: when t≥2mm
1≥2t
Figure 4 Position of the hole in the bending part
7.1.5 Symmetrical bending, the left and right bending radii should be consistent to ensure that there is no slippage during the bending process. 7.1.6 When bending, the bending line of the workpiece should be perpendicular to the rolling wire flow direction of the sheet as much as possible. If this requirement cannot be met (such as the workpiece has two bends in different directions), the angle between the bending line and the wire flow direction should be no less than 30°. 7.2 Bending part accuracy
The accuracy of the bending part is related to many factors, such as the mechanical properties of the bending part material and the material thickness tolerance, the mold structure and mold accuracy, the number of processes and the order of processes, and the shape and size of the bending part itself. The tolerance grade of the bending part is recommended to be selected according to Table 7, and the angle tolerance of the bending part is recommended to be selected according to Table 8. 35
11 Stamping safety operation
11.1 Eliminate or reduce dangerous areas
JB/T6234—1992
11.1.1 The sharp corners of the external part that are easily touched by the operator's hands should be de-edged, rounded, grooved or made into bevels. 11.1.2 Reduce the contact area between the upper die and the lower die. 11.2 Use various protective devices to prevent both hands from entering the dangerous area of the mold. 11.3 Try to use mechanized automation devices instead of manual operations. 11.4 Use hand tools instead of hands to enter the dangerous area for operation. 12 Stamping production management
12.1 The design drawings of stamping parts should be reviewed and signed by stamping professional process technicians (technicians). 12.2 The transportation and storage of stamping parts should have appropriate workstations and equipment. 12.3 Pay attention to rust prevention during the storage of stamping parts. The production site should have relevant process documents compiled by the technical department. 12.4
There must be a complete tooling acceptance and maintenance system. Perform handover procedures and records.
Pay attention to production safety.
Presses (punches) must be regularly inspected and maintained. Additional notes:
This standard was proposed and managed by the National Electric Tool Standardization Technical Committee. This standard was drafted by Shanghai Hitachi Electric Tools Co., Ltd. The main drafter of this standard is Huang Qiyun.2 Accuracy of bending parts
The accuracy of bending parts is related to many factors, such as the mechanical properties of the bending parts materials and the material thickness tolerance, the mold structure and mold accuracy, the number of processes and the order of processes, and the shape and size of the bending parts themselves. The tolerance grade of bending parts is recommended to be selected according to Table 7, and the angle tolerance of bending parts is recommended to be selected according to Table 8. 35
11 Safe operation of stamping
11.1 Eliminate or reduce dangerous areas
JB/T6234—1992
11.1.1 The sharp corners of the external part that are easily touched by the hands of the operator should be de-edged, rounded, grooved or made into bevels. 11.1.2 Reduce the contact area between the upper die and the lower die. 11.2 Use various protective devices to prevent both hands from entering the dangerous area of the mold. 11.3 Try to use mechanized automation devices instead of manual operations. 11.4 Use hand tools instead of hands to enter the dangerous area for operation. 12 Stamping production management
12.1 The design drawings of stamping parts should be reviewed and signed by professional stamping technicians (techniques). 12.2 There should be appropriate workstations and equipment for the transportation and storage of stamping parts. 12.3 Pay attention to rust prevention during the storage of stamping parts. The production site should have relevant process documents compiled by the technical department. 12.4
There must be a complete tooling acceptance and maintenance system. Perform handover procedures and records.
Pay attention to safety in production.
Presses (punches) must be regularly inspected and repaired. Additional notes:
This standard is proposed and managed by the National Technical Committee for Standardization of Electric Tools. This standard is drafted by Shanghai Hitachi Electric Tools Co., Ltd. The main drafter of this standard is Huang Qiyun.2 Accuracy of bending parts
The accuracy of bending parts is related to many factors, such as the mechanical properties of the bending parts materials and the material thickness tolerance, the mold structure and mold accuracy, the number of processes and the order of processes, and the shape and size of the bending parts themselves. The tolerance grade of bending parts is recommended to be selected according to Table 7, and the angle tolerance of bending parts is recommended to be selected according to Table 8. 35
11 Safe operation of stamping
11.1 Eliminate or reduce dangerous areas
JB/T6234—1992
11.1.1 The sharp corners of the external part that are easily touched by the hands of the operator should be de-edged, rounded, grooved or made into bevels. 11.1.2 Reduce the contact area between the upper die and the lower die. 11.2 Use various protective devices to prevent both hands from entering the dangerous area of the mold. 11.3 Try to use mechanized automation devices instead of manual operations. 11.4 Use hand tools instead of hands to enter the dangerous area for operation. 12 Stamping production management
12.1 The design drawings of stamping parts should be reviewed and signed by professional stamping technicians (techniques). 12.2 There should be appropriate workstations and equipment for the transportation and storage of stamping parts. 12.3 Pay attention to rust prevention during the storage of stamping parts. The production site should have relevant process documents compiled by the technical department. 12.4
There must be a complete tooling acceptance and maintenance system. Perform handover procedures and records.
Pay attention to safety in production.
Presses (punches) must be regularly inspected and repaired. Additional notes:
This standard is proposed and managed by the National Technical Committee for Standardization of Electric Tools. This standard is drafted by Shanghai Hitachi Electric Tools Co., Ltd. The main drafter of this standard is Huang Qiyun.
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