JB/T 9180.1-1999 JB/T 9180.1-1999 Tolerances for steel refrigeration extrusions JB/T9180.1-1999 Standard download decompression password: www.bzxz.net

JB/T 9180.1-1999
This standard adopts the relevant contents of the German Technical Standards compiled by Feldemman and the German Engineers Association (VDI) in Germany. This standard is a revision of ZBJ32006-89 "Tolerances of Steel Cold Extrusion Parts". The technical content supplements and modifications are as follows: 1) In 3.1 Classification of tolerance grades, the definition of precision tolerance is added. 2) In 3.2.1 Calculation method of shape complexity coefficient Fk of extruded parts, the outer corridor inclusion volume of preformed ring and final formed part is given a precise definition.
3) According to the definition of the outer contour inclusion volume of preformed and final formed workpiece, the calculation method of shape complexity coefficient F in cold extrusion tolerance prediction of Appendix A (suggestive appendix) is modified, and the inclusion volume of preformed ring and final formed part is marked in Figure A1 respectively.
This standard replaces ZBJ32006-89 from the date of implementation. Appendix A of this standard is a suggestive appendix.
This standard is proposed and managed by the National Technical Committee for Forging Standardization. The drafting unit of this standard is Beijing Institute of Mechanical and Electrical Engineering. The drafters of this standard are Li Chuanjin and Wang Bingyi. 230
1 Scope
Standard of the Machinery Industry of the People's Republic of China
Tolerances for Cold Extruded Steel Parts
Dimensional tolerance for cold extruded steel partsJB/T 9180.-.1999
Replaces ZBJ32006:89
This standard specifies the dimensional tolerances and usage methods of cold extruded steel solid parts, hollow parts and flange parts. This standard is applicable to cold extruded parts produced in batches by cold extrusion. This standard is not applicable to workpieces produced by cold heading, warm extrusion and hot extrusion. 2 Symbols
This standard adopts the following symbols:
--h: flange thickness or bottom thickness;
Fk: shape complexity coefficient;
L: length of the extruded part of the workpiece;
-M.M2.M.: material coefficient.
3 Technical elements
3.1 Tolerance grade
The tolerances in this standard are divided into two grades: ordinary grade and precision grade. Ordinary grade tolerance refers to the tolerance that can be achieved by general cold extrusion methods. Precision grade tolerance can be used for all dimensions of cold extrusion parts, and can also be used for local dimensions of cold extrusion parts. Precision grade tolerance is suitable for cold extrusion parts with higher technical requirements, but it requires additional manufacturing processes to achieve.
3.2 Main factors for determining tolerances
3.2.1 Extrusion shape complexity coefficient F
Extrusion shape complexity coefficient F refers to the ratio of the volume contained by the rough or preformed outer contour to the volume contained by the final formed outer contour of the workpiece, as shown in formula (1):
Wherein, the rough or preformed outer contour contained volume V,--the final formed outer contour contained volume of the workpiece. The preformed and final formed part outer contour contained volume refers to the volume of the cylinder determined by the maximum outer corridor size. For example, when the left side of Figure 1 is a rough ring and the right side is an extruded part, V. V, is calculated according to formula (2) and formula (3): V
Wherein: De, LaDi, L,, D2, L see Figure 1. Approved by the National Machinery Industry Week on June 24, 19991)
Implemented on January 1, 2000
JB/T 9180. 1-1999
The shape complexity coefficient of extrusion parts is divided into two levels: general: Fk>0.5; complex: F≤0.5. Note: For reverse extrusion parts, when F≥0.5, in theory, the larger the F, the more difficult the process, but in actual production, a more complex coefficient is basically not selected.
Inclusive volume
a) Cold extrusion rough or preformed
3.2.2 Selection of material coefficient
The material coefficient of cold extrusion is divided into three levels: MI, M2, M3 Figure 1
The material of cold extrusion is divided according to the Brinell hardness in the annealed state: M: HB≤130;
Mz: HB≥130~180;
Ma: HB>180.
3.2.3 Basic dimensions of cold extrusion
The dimensions marked on the cold extrusion drawing (the tolerance is determined according to this dimension) are shown in Figure 2. Figure 2
3.3 Method for determining tolerances
3.3.1 Tolerance of solid parts
b) Cold extruded parts
For workpieces extruded by forward extrusion, reverse extrusion or combined extrusion methods, the dimensional tolerance of the solid part can be determined by referring to Table 1 based on factors such as the shape complexity coefficient, material coefficient, basic dimensions, etc. of the extruded parts. 232
Basic size
≥fi~10
≥18~30
>30～50
>50~80
-80～100
Shape complexity coefficient Fk
3.3.2 Diameter tolerance of hollow parts
JB/T 9180. 1-1999
Diameter tolerance of solid parts
Material coefficient
Tolerance grade
Ordinary grade
Precision grade
For cold extrusions extruded by forward extrusion, reverse extrusion or combined extrusion, the inner and outer diameter tolerances of the hollow parts can be determined by referring to Table 2 based on factors such as the shape complexity coefficient, material coefficient and basic size of the extruded parts. Table 2 Hollow Parts Diameter Tolerance
Basic Size
>0～6
>6～10
>10～18
>18～30
>30~50
≥50～80
>80~100
Shape Complexity Factor Fk
Quality Factor
Inner Diameter Tolerance Grade
Ordinary Grade
Precision Grade
Outer Diameter Tolerance Grade
Ordinary Grade
Precision Grade
±0.024+0. 090 | | tt | | ±0.075 ± 0.029 ± 0.110 + 0.038 | |±0.2001±0.080/±0.230/
±0.270±0.105—0.270
±0.125±0.315±0.125
-0. 360:-+0. 145
2 0. 360/± 0. 145
3.3.3 Wall thickness tolerance of hollow parts
For cold extruded parts extruded by forward extrusion, reverse extrusion or combined extrusion, the wall thickness tolerance of the hollow part can be determined by referring to Table 3 based on factors such as wall thickness S and material coefficient.
≥0～0.6
>0. 6 ~~1. 2
>1. 2~2. 0
>2. 0～3. 5
>3. 5~6. 0
≥>10～15
3.3.4 Tolerance of flange thickness and bottom friction
JB/T 9180.1---1999
Tolerance of wall thickness of hollow parts
General grade
The tolerance of bottom thickness of cold extruded hollow parts and the tolerance of flange thickness of solid parts shall be determined by referring to Table 4. Flange thickness and bottom thickness tolerance
Ordinary grade
Tolerance grade
Precision grade
3.3.5 How to use the tolerance table
>2~10
≥10~15/≥15~25
Precision grade
≥40 50 1 2507t
The inner and outer diameter tolerances, wall thickness tolerances, bottom thickness tolerances, and flange thickness tolerances of solid and hollow parts can be determined through Tables 1, 2, 3, and 4. First, select the corresponding range according to the basic size, and then move horizontally to the right. If the shape complexity coefficient is F0.5, continue to move right along the horizontal line until the vertical line of the corresponding material coefficient column intersects. When the material coefficient is M, continue to move to the stone along the horizontal line. For material coefficients of M2 and M, use the same method to move down along the oblique line to the position of M2 and M, and continue to move to the right until the vertical column of the required size is reached, and the required tolerance value is obtained. If the shape complexity coefficient Fk>0.5, move up one grid along the oblique line, and then extend horizontally until it intersects with the vertical line of the corresponding material coefficient column, and then look up the table according to the above method, 234
JB/T 9180.1---1999
Appendix A
(Suggested Appendix)
Example of tolerance of cold extruded parts
A1 When the hollow part is made of No. 10 steel, HB110, and the material coefficient is M, its outer dimensions are shown in Figure A1. The final size tolerance is calculated according to formula (1):
Calculated according to formula (2):
×45″×45
Calculated according to formula (3):
X 91 125
×45″×75
Tolerance of outer diameter 35mm:
See Table 2. The tolerance of ordinary grade is ±0.165mm
The tolerance of precision grade is ±0.065mm
Tolerance of outer diameter 30mm:
See Table 2. The tolerance of ordinary grade is ±0.135mm
The tolerance of precision grade is ±0.055mm
Tolerance of inner diameter 20mm:
See Table 2. The tolerance of ordinary grade is ±0.090mm
The tolerance of precision grade is ±0.035mm
Tolerance for wall thickness is 5mm:
Check Table 3. Tolerance for ordinary grade is ±0.25mmbzxz.net
Tolerance for precision grade is ±0.08mm
Tolerance for bottom thickness is 10mm:
Check Table 4. Tolerance for ordinary grade is ±0.30mm
Tolerance for precision grade is ±0.12mm
X151875
/×151875
×91125/
a) Preformed parts
JB/T 9180.1—1999
Inclusive volume
b) Cold extrusion parts
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