JB/T 9179.7-1999 JB/T 9179.7-1999 Machining allowances and tolerances of free forgings on hydraulic presses Cylinders JB/T9179.7-1999 Standard download decompression password: www.bzxz.net

JB/T9179.7—1999
This standard is a revision of ZBJ32003.7—88 "Machining allowance and tolerance of free forgings on hydraulic presses". When revising
, the original text was edited and the main technical contents were modified as follows: 1. The determination of the increase coefficient n on the original length allowance was changed to be determined according to the length of the forging; the content of 4.4 in the general provisions was cancelled.
This standard replaces ZBJ32003.7--88 from the date of implementation. This standard was proposed by the National Forging Standardization Technical Committee and is under the jurisdiction of II. The responsible drafting unit of this standard: Shanghai Heavy Machinery Factory. The main drafters of this standard: Wang Qianhe and Xie Peide. 377
Machinery Industry Standard of the People's Republic of China
Machining allowances and tolerances of open die forgings on hydraulic press--Cylinder
Machining allowances and tolerances of open die forgings on hydraulic press--CylinderThis standard specifies the allowances and tolerances of open die forgings on hydraulic press--Cylinder. JB/T 9179. 7--1999
Replaces ZBJ32003.7-88
This standard is applicable to cylinder forgings that are finally finished through the mandrel drawing process and the part size meets the requirements of L>1.2D. 2 Allowances and Tolerances
The machining allowances and tolerances of open die forgings on hydraulic presses shall comply with the requirements of Figure 1 and Tables 1 and 2. Figure 1
Approved by the State Bureau of Machinery Industry on 1999-06-24 378
Implemented on 200001-01
Part length
16002500
2 5004 000
6 3009 000
9 000/11 000 | | tt | | 1100012000 | ±13
42±14
JB/T 9179. 7-1999
Part diameter D
36±12
1 0001250
Margin α and limit deviation
38±13
[40±13|421411±15
38-t13
44±1547+16501753-
44±15/47±16|50
47±16
50±1753±18|56±1959±20|6
3General provisionsbzxZ.net
[56±19[59±20|62±21
53 →+18
8|56±1959±2062±21
65±22
68±23
165+22
62±21
2268±237124
3.1 The length allowance and tolerance of the cylinder forging is n times the maximum outer diameter allowance, n is the increase coefficient, which can be found in Table 2. 3.2 The wall thickness of the cylinder forging shall not be less than 100mm. If it is less than this value, the wall thickness can be increased to 100mm. 4
Application example
Calculate the size of the simplified forging:
The size of the part is: D700mmd=300mm, L1500mm. It is found that the allowance and limit deviation on D are 38mm±13mm, n=3.0. The basic size of the forging is:
D,=700+38=738mm (take 740mm)
Limit deviation±13mm;
d=30038×1.5=243mm (take 245mm)
Limit deviation±19mm;
L=1500+38×3.0=1614mm (take 1615mm) Limit deviation+38mm.
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