GB/T 21471-2008Machining allowances and tolerances for steel open die forgings on hammer -- Shafts (English PDF)

Foreword

This Standard revised GB/T 15826.6-1995 Machining Allowances and Tolerances for Steel

Open Die Forgings on Hammer - Shaft without Steps, GB/T 15826.7-1995 Machining

Allowances and Tolerances for Steel Open Die Forgings on Hammer - Shaft with Steps, GB/T

15826.8-1995 Machining Allowances and Tolerances for Steel Open Die Forgings on Hammer

- Single Throw Crankshaft, and GB/T 15826.9-1995 Machining Allowances and Tolerances for

Steel Open Die Forgings on Hammer - Forging without Machining. The major revised contents

are as follows.

--- Integrate GB/T 15826.6-1995, GB/T 15826.7-1995, GB/T 15826.8-1995, and GB/T

15826.9-1995 into one standard.

--- Add table of contents and foreword.

--- Add normative references.

--- Delete the calculation examples in Section 3.4 of GB/T 15826.6-1995, and its content is

given as "Appendix A".

The Appendix A of this Standard is informative.

This Standard was proposed by China Machinery Industry Federation.

This Standard shall be under the jurisdiction of National Technical Committee on Forging of

Standardization Administration of China.

Drafting organizations of this Standard. Shanghai Hudong Forging Factory; and Pinghu

Chenren Meter Co., Ltd.

Chief drafting staffs of this Standard. Sun Changfen, and Dong Zhusheng.

The historical editions replaced by this Standard are as follows.

--- GB/T 15826.6-1995;

--- GB/T 15826.7-1995;

--- GB/T 15826.8-1995;

--- GB/T 15826.9-1995.

Machining Allowances and Tolerances for Steel Open Die

Forgings on Hammer – Shafts

1 Scope

This Standard specifies the machining allowances and tolerances of open die forgings such as

shafts without steps, shafts with steps, and single throw crankshaft, as well as the allowable

limit deviations of forging without machining.

This Standard applies to open die forgings of carbon steel and alloy steel with a carbon content

not exceeding 0.9% and a total content of other alloy components not exceeding 4%.

For open die forgings that exceed the range specified in this Standard, the allowances and

tolerances shall be determined by negotiation between the supplier and the purchaser.

2 Normative References

The provisions in following documents become the provisions of this Standard through

reference in this Standard. For dated references, the subsequent amendments (excluding

corrigendum) or revisions do not apply to this Standard, however, parties who reach an

agreement based on this Standard are encouraged to study if the latest versions of these

documents are applicable. For undated references, the latest edition of the referenced document

applies.

GB/T 21469 Machining allowances and tolerances for steel open die forgings on hammer

- General requirement

JB/T 9179.2 Machining allowance and tolerance of open die forgings on hydraulic press -

Round shaft, square shaft and rectangular cross-section

JB/T 9179.3 Machining allowance and tolerance of open die forgings on hydraulic press -

Stepped shaft

3 Shafts without Steps

4 Shafts with Steps

4.1 The ratio of the total length L of open die forging of shaft with step with the circular cross-

section to the maximum step diameter D (L/D) shall be greater than 2.5.

5 Single Throw Crankshaft

5.1 If the crank height H (or D) of single throw crankshaft and eccentric shaft open die forgings

is <=500 mm, the crank length L shall be <= 600 mm.

6 Forgings without Machining