This standard specifies the basic requirements for position tolerance, material and hardness, appearance and surface roughness, marking and packaging of hand-held 1:50 taper pin reamers. This standard applies to hand-held 1:50 taper pin reamers and hand-held long-blade 1:50 taper pin reamers. GB/T 4248-2004 Technical conditions for hand-held 1:50 taper pin reamers GB/T4248-2004 Standard download decompression password: www.bzxz.net

ICS 25. 100. 30
National Standard of the People's Republic of China
GB/T4248-2004
Replaces GB/T4248—1984
Technical conditions for hand taper 1 : 50 pin reamersIssued on 2004-02-10
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of ChinaAdministration of Standardization of the People's Republic of China
Implementation on 2004-08-01
GB/T 4248-2004
This standard replaces GB/T 4248-1984 "Technical conditions for hand taper 1 : 50 pin reamers" from the date of its implementation. Compared with GB/T4248-1984, the main changes of this standard are as follows: the performance test part in GB/T4248-1984 is cancelled; the material part in GB/T4248-1984 is modified, and the material is changed from W18Cr4V to W6Mo5Cr4V2; the marking and packaging part in GB/T4248-1984 is modified; - surface roughness is added.
This standard is proposed by China Machinery Industry Federation. This standard is under the jurisdiction of the National Technical Committee for Tool Standardization (SAC/TC91). The drafting unit of this standard: Chengdu Tool Research Institute. The main drafters of this standard: Liu Yuling, Zha Guobing. The previous versions of the standards replaced by this standard are: GB/T 4248-1984.
1 Scope
Hand-held 1:50 taper pin reamer
Technical conditions
GB/T 4248—2004
This standard specifies the basic requirements for the position tolerance, material and hardness, appearance and surface roughness marking and packaging of hand-held 1:50 taper pin reamer. Www.bzxZ.net
This standard applies to hand-held 1:50 taper pin reamer and hand-held long-blade 1:50 taper pin reamer. Position tolerance of reamer
The position tolerance of reamer shall be in accordance with Table 1.
Radial runout of the working part to the common axis 100
Tolerance of the diameter difference of the reamer in a length of 100mm 3 Materials and hardness
3.1 Materials
>100～200
d>3～~20
Unit: mm
d>20～50
The reamer is made of W6Mo5Cr4V2 or other high-speed steel with equivalent performance. The handle of the welding reamer is made of 45 steel or other steel with equivalent performance. The reamer is also allowed to be made of 9SiCr or other alloy tool steel with equivalent performance. 3.2 Hardness
3.2.1 Hardness of the working part:
High-speed steel reamer is: 63HRC～66HRC; alloy tool steel reamer is: 62HRC65HRC. 3.2.2Hardness of the square head of the shank:
Integral reamer: diameter d<3mm not less than 40HRC; diameter d≥3mm is 40HRC～55HRC.
Welded reamer: 30HRC～45HRC.
Appearance and surface roughness
4.1Appearance
The surface of the reamer shall not have defects such as cracks, scratches, rust and grinding burns that affect the performance. 4.2Surface roughness
The surface roughness of the reamer is:
Front: Rz3.2μm;
Rear: Rz6.3μm;
Handle: Ral.6μm;;
GB/T 4248--2004
Conical land: Rz6.3um.
5 Marking and Packaging
5.1 Marking
5.1.1 The product shall be marked with (reamers with diameter d<3mm may not be marked, reamers with diameter d=3mm～6mm may only be marked with the reamer diameter and working part length):
trademark of the manufacturer or seller;
reamer diameter;
working part length;
-material code (alloy tool steel reamers do not have material marked), taper. 5.1.2 The packaging box shall be marked with:
name, address and trademark of the manufacturer or seller; product name;
reamer diameter;
working part length;
-standard number;
-material;
number of pieces;
year and month of manufacturing.
5.2 Packaging
The reamer shall be treated with rust prevention before packaging. The packaging should be firm to prevent damage during transportation.
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