This standard specifies the machining allowances and tolerances of free forgings of the smooth shaft type with round, square, hexagonal, octagonal and rectangular (B/H≤5) cross sections. This standard applies to free forgings of the smooth shaft type with part size L＞2.5D (or A, B, S). GB/T 15826.6-1995 Machining allowances and tolerances of free forgings of steel on hammers, smooth shaft type GB/T15826.6-1995 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Machining allowances and tolerancesforsteel opendieforgings on hammer-Shaft without steps
Machining allowances and tolerancesforsteel opendieforgings on hammer-Shaft without steps
Subject content and scope of application
GB/T 15826.6—1995
This standard specifies the machining allowances and tolerances for open die forgings of circular, square, hexagonal, octagonal and rectangular (B/H≤5) cross sections.
This standard is applicable to open die forgings of part size L>2.5D (or A, B, S). 2 Allowances and tolerances
The machining allowances and tolerances for open die forgings of open shaft shall comply with the provisions of Figure 1 and Table 1. 0.50
Approved by the State Bureau of Technical Supervision on December 13, 199560
Implementation on August 1, 1996
Part size
DA, S, B, H.
GB/T 15826.6--1995
Machining allowance and tolerance of optical axis forgingsPart length L
Allowance a and limit deviation
Forging precision grade F
1677
Forging precision grade E
Note: For the allowance of rectangular section H, use H instead of H to look up in the table, H-B+H—General explanation
When the ratio of the two sides of the optical axis of a rectangular section B/H ≥ 2.5, the allowance a of H increases by 20%. 3.1wwW.bzxz.Net
When the part size 1/D (or I/B)>20, the allowance a is increased by 30%. 1600
23±10
3.3The rest shall comply with the provisions of GB/T15826.1 "General requirements for machining allowances and tolerances of steel free forgings on hammers". 3.4For the optical axis of a rectangular section, the larger side B and length L are used to find α in Table 1 to determine the allowances of L and B. The allowance α of H is determined by looking up the length L and the calculated value H.
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Example: Calculate the forging size of a rectangular cross-section optical axis: Assume that the part size is B=200mm, H=100mm, L=3500mm, and the forging accuracy grade is F. Look up the table: Based on B and L, we get a=18±8mm
Calculate: The allowance and limit deviation of length 1 is 2a=36±16mm The allowance and limit deviation of width B is a=18±8mm Calculate: H,B+H_200+100
=150mm
Look up the table: Based on H, and L, we get α=17±7mm
The forging size obtained is:
GB/T 15826.6—1995
B.=(200+18)±8=218±8mm
H=(100+17)±7117±7mm
Lo（3500+36)±163536±16mm
Additional remarks;
This standard is proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Forging Standardization. This standard was drafted by the Shanghai Mechanical and Electrical Industry Administration and other units. The main drafters of this standard are Dong Zhusheng, Pan Baimao, Lv Xiancheng, Zhang Bingji, and Xie Huazhen. From the date of implementation of this series of standards, the original JB4289--81 "Machining allowances and tolerances of steel free forgings on hammers" standard will be invalid. 241
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