JB/T 9179.1-1999 JB/T 9179.1-1999 General requirements for machining allowances and tolerances of free forgings on hydraulic presses JB/T9179.1-1999 Standard download decompression password: www.bzxz.net

JB/T9179.1-1999
This standard is a revision of ZBJ32003.1-88 "Machining allowances and tolerances for free forgings on hydraulic presses". The original text has been edited and the main technical contents have been modified as follows: 1. The content "weight not exceeding 100 tons" has been cancelled in the scope of application. This standard replaces ZBJ32003.1--88 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Forging Standardization. The responsible drafting unit of this standard is Shanghai Heavy Machinery Plant. The main drafters of this standard are Wang Qianhe and Xie Peide. General requirements". Under revision
1 Scope
Standard of the Machinery Industry of the People's Republic of China
Machining allowances and tolerances of open die forgings on hydraulic press--General requirements
Machining allowances and tolerances of open die forgings on hydraulic press--General requirementsThis standard specifies the general requirements for machining allowances and tolerances of open die forgings on hydraulic press. JB/T9179.1-1999
Replaces ZBJ32003.1·88
This standard applies to carbon steel and alloy steel forgings for free forging and general use on hydraulic press (alloy steel: except for carbon content, the content of other alloy components shall not exceed 10%; carbon steel: carbon content shall not exceed 0.8%). The machining allowances and tolerances specified in this standard are applicable to single piece or small batch production. For forgings that exceed the range of material, size and shape specified in this standard, or have special requirements for mechanical properties, the allowances and tolerances shall be determined by negotiation between the supply and demand parties.
2 Cited standardswww.bzxz.net
The provisions contained in the following standards constitute the provisions 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. JB/T9179.2—1999 Machining allowances and tolerances of free forgings on hydraulic presses. Round shafts, square shafts and rectangular sections. JB/T9179.3-1999 Machining allowances and tolerances of free forgings on hydraulic presses. Step shafts. JB/T9179.4-1999 Machining allowances and tolerances of free forgings on hydraulic presses. Discs and punchings. JB/T9179.5-1999 Machining allowances and tolerances of free forgings on hydraulic presses. Short cylinders. JIB3/T 9179.6—1999 Machining allowance and tolerance of free forgings on hydraulic press Module category JB/T9179.7—1999 Machining allowance and tolerance of free forgings on hydraulic press Cylinder category
JB/T9179.8--1999 Machining allowance and tolerance of free forgings on hydraulic press Ring category 3 General provisions
3.1 This standard does not specify the allowance of forging mechanical properties test specimens, heat treatment allowance, hanging chucks and other special allowances. 3.2 The allowances and tolerances specified in this standard can be added to the basic dimensions marked on the part finishing drawing or on the basic dimensions marked on the part roughing drawing according to different process requirements. 3.3 When parts only need to be machined from one side, the allowance should be 1/2 of the specified value, the upper deviation remains unchanged, and the lower deviation is 1/2 of the specified value. 3.4 Forgings do not add tolerances on the second surface, and are determined according to the shape and size of the forgings in accordance with JB/T9179.2~~9179.8. The allowance is zero. 3.5 This standard stipulates that the upper and lower deviations of forgings are approximately 1/3 of the corresponding allowances. 3.6 The basic dimensions of forgings are allowed to be rounded to the end of 5 or 0. If the basic dimension ends in 1, 2, 6 and 7, round to the smaller side; if the basic dimension ends in 3, 4, 8 and 9, round to the larger side. Approved by the State Machinery Industry Bureau on June 24, 1999 360
Implementation on July 1, 2000
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