JB/T 9175.2-1999 JB/T 9175.2-1999 Quality of precision blanking parts JB/T9175.2-1999 Standard download decompression password: www.bzxz.net

·JB/T9175.2—1999
This standard adopts the fourth chapter “Quality of Precision Blanking Parts” of VDI3345—80 “Precision Blanking Parts” in a non-equivalent manner. This standard is a revision of JB/Z280-~87 “Quality of Precision Blanking Parts”. During the revision, the preface was added, the description of "consistency" in the original standard size tolerance was cancelled, and editorial changes were made to other contents. The main technical content has not changed. This standard replaces JB/Z280-87 from the date of implementation. Appendix A of this standard is the appendix of the standard.
This standard is proposed and managed by the National Technical Committee for Forging Standardization. The responsible drafting unit of this standard: Beijing Institute of Mechanical and Electrical Engineering. The main drafters of this standard: Li Ronghong, Tu Guangqi, Zhao Yanqi. 212
1 Scope
Machinery Industry Standard of the People's Republic of China
Quality of fine blanked parts
Quality of fine blanked parts This standard applies to the strong edge pressing precision blanking process. 2 Reference standards
JB/T 9175. 2-1999
Replaces JB/Z280-：87
The clauses contained in the following standards constitute the clauses of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T131-1993 Mechanical drawing surface roughness symbols, codes and annotations GB/T1031—1995 Surface roughness parameters and their values ​​3 Quality of precision blanking parts
The quality of precision blanking parts includes:|| tt||Dimensional tolerance;
Shear surface quality;
Folding angle;bzxz.net
Shear surface verticality;
Burr.
This standard includes the first three items, namely, dimensional tolerance, shear surface quality and collapsed angle. The last three items are determined by the designer based on the technical requirements of the parts and the characteristics of the precision blanking process. 3.1 Dimensional tolerance
The dimensional tolerance that can be achieved for precision blanking parts depends on the following factors:\-Mold manufacturing accuracy;
Cutting edge condition;
Press;||tt ||Lubricant;
· Type of workpiece material, metallographic structure and thickness, and complexity of the geometric shape of precision blanking parts. See Table 1 for the dimensional tolerances that can be achieved by precision blanking. Table 1 Achievable dimensional tolerance grades
Material thickness
Approved by the State Machinery Industry Bureau on June 24, 1999 Internal shape
Tensile strength limit to 600N/mm
Implemented from January to January 2000
Material thickness
8～10
3.2, Shear surface quality
9～10
9～10
JB/T9175.2—-1999
Table 1 (end)
Tensile strength limit to 600N/mm2
Shear surface quality of precision blanking parts, including surface roughness, surface quality rate and allowable tearing grade. The shear surface roughness that can be achieved during precision blanking depends on the following factors: surface roughness of the blanking component;
edge condition;
Lubricant:
Press:
I. Type, metallographic structure and thickness of the part material. The shear surface roughness of precision blanking parts is evaluated according to the arithmetic mean deviation Ra value of the profile in GB/T1031. The shear surface roughness that can be achieved by precision blanking parts is Ra0.20.32μm, generally Rao0.63~2.5um. The measurement position of shear surface roughness is shown in Figure 1. Measurement position: along the center of the shear surface thickness. Measurement direction: perpendicular to the shear direction.
The state of the precision blanking shear surface and the meaning of the symbols used are shown in Figure 2. Figure 2
In the figure: t——material thickness;
t.-…When there is surface peeling at the shear terminal, the minimum part of the smooth shear surface is the percentage of the material thickness; 214
JB/T 9175. 2—-1999
-When there is scaly surface peeling at the shear terminal, the minimum part of the smooth shear surface is the percentage of the material thickness; b-—maximum allowable scaly surface peeling width (the sum of all 6 shall not be greater than 10% of the relevant contour part); surface peeling depth:
burr height;
collapse angle width;
collapse angle depth;
-…maximum width at the tear;
A—surface peeling zone at the shear terminal.
Surface integrity is divided into five levels, listed in Table 2; allowable tearing is divided into four levels, listed in Table 3Table 2 Surface integrity level of precision blanking parts
Allowable tearing level of precision blanking parts
The code for the roughness of the shear surface of precision blanking parts is represented by the symbol √ or √ in GB/T131. √ is used when the shear surface is not allowed to have surface peeling and tearing: For example: \ indicates that the shear surface roughness is Ra0.63um, the surface integrity rate is level I, and there is no tearing. 50
When the shear surface is allowed to have surface peeling or tearing, the Roman numerals Ⅱ, 班, N, and V are used on the upper right horizontal line of the symbol to indicate the level of surface integrity respectively, and the Arabic numerals 1, 2, 3, and 4 are used to indicate the level of allowable tearing respectively. For example: indicates that the shear surface roughness is Ral.25μm, and the surface integrity rate is level I. 变 indicates that the shear surface roughness is Ra2.5um, and level 2 tearing is allowed. The marking of the roughness of the shear surface on the precision blanking part drawing shall be in accordance with the provisions of Chapter 3 of GB/T131--1993. An example of the marking of the quality of the shear surface of the precision blanking part is shown in Figure 3. 2
The rest 2
In actual production, it is recommended to use standard push samples as the basis for evaluating the surface integrity rate and allowable tearing of precision blanking parts; the standard samples are selected by the relevant departments from the test punching parts. 3.3 Collapse
During precision blanking, there is a collapse angle opposite to the burr side of the workpiece. Its size depends on the geometric shape, material, strength and thickness of the workpiece.
Under the conditions of given material thickness and material type, the smaller the fillet radius and angle α, the greater the width of the angle. If the fillet radius and angle are given, reducing the material thickness and increasing the strength will reduce the depth and width of the collapse angle. Figure 4 shows the standard value of the maximum collapse angle at the minimum allowable fillet, which is applicable to materials with a tensile strength below 450N/mm. For materials with a thickness of less than 4mm, a single gear ring is used, and for materials with a thickness of more than 4mm, a double gear ring is used. Example: If the part angle α is known to be 120° and the material thickness is 5mm, α==0.6mm can be obtained from Figure 4. 30°60\90°120°α
6. 4 4. 7/3. 211. 7
5.6-4.12.81.5
4. 8 3. 52. 41. 3
4. 0 -2. 9/2. 041. 1
3. 2 2. 31 . 60. 9
2. 4 +1. 71. 20. 7
1. 6 +1. 140. 80. 5 4
0. 8 -0. 540. 40. 3-
Material thickness
12.5～16
JB/T 9175. 2-1999
Appendix A
(Standard Appendix)
The dimensional tolerance grades that can be achieved for precision blanking parts in VDI3345 are the tensile strength limit of 600N/mm
9～10
10～11
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