This standard specifies the dimensions and marking examples of Morse taper shank long-edge machine reamers. This standard includes three tables: - recommended diameters and corresponding dimensions in millimeters; - recommended diameters and corresponding dimensions in inches; - dimensions divided by diameter in millimeters and inches. In addition, the length and cutting part diameter tolerances are also specified. This standard applies to high-speed steel Morse taper shank long-edge machine reamers with diameters greater than 6mm to 85mm. GB/T 4243-2004 Morse taper shank long-edge machine reamers GB/T4243-2004 Standard download decompression password: www.bzxz.net

ICS 25. 100. 30
National Standard of the People's Republic of China
GB/T4243—2004
Replaces GB/T4243—1984
Long fluted machine reamers, Morse tape shanks
Long fluted machine reamers, Morse tape shanks(ISO236-2:1976,MOD)
Issued on 2004-02-10
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Administration of Standardization of the People's Republic of China
Implementation on 2004-08-01
This standard modifies and adopts ISO236-2:1976 "Long fluted machine reamers, Morse tape shanks" (English version). Compared with ISO236-2:1976, this standard has the following technical differences and editorial modifications: In the normative references of GB/T 4243-2004, ISO236-1 "Hand Reamers" and ISO521 "Machine Reamers with Straight Shanks and Morse Taper Shanks" are deleted; ISO296 is replaced by GB/T1443 "Self-clamping Tapers for Machine Tool and Tool Shanks"; GB/T4246 "Special Tolerances for Reamers" is added; marking examples are added; the symbol "," is used instead of the comma "," used as a decimal point; "this standard" is used instead of "this international standard"; the foreword of the international standard is deleted; normative Appendix A (diameter tolerances of reamer for machining H7, H8, and H9 grade holes) is added; - Change 1 to L and 1 to l in Figures and Tables 1, 2, 3, and 4 of ISO236-2. This standard replaces GB/T4243-1984 "Taper Shank Long Edge Machine Reamer" from the date of implementation. Compared with GB/T4243-1984, this standard has the following changes: the standard reamer diameter tolerance m6 is added; the imperial size is added;
Chapter 3 Interchangeability is added;
The chapters and clauses of GB/T4243-1984 are adjusted according to ISO236-2; the reference dimensions and surface roughness markings in the GB/T4243-1984 drawings are cancelled (the surface roughness is included in the technical conditions standard);
The reference dimensions in the GB/T4243-1984 table: l1, a, f and number of teeth are cancelled;
The reference dimensions in the GB/T4243-1984 table: l1, a, f and number of teeth are cancelled according to ISO236 -2 The diameter range in the table of GB/T4243-1984 has been adjusted; the table in GB/T4243-1984 has been adjusted according to ISO236-2 to: Table 1 Length tolerance, Table 2 Recommended diameter and corresponding size (metric), Table 3 Recommended diameter and corresponding size (imperial) and Table 4 Sizes divided by diameter; - The tolerance of the diameter d of the machine reamer for machining H7, H8 and H9 grade precision holes in the table of GB/T4243-1984 is listed in Appendix A; the marking example has been modified;
Appendix A (diameter tolerance of reamer for machining H7, H8 and H9 grade holes) has been added. Appendix A of this standard is a normative appendix.
This standard was proposed by the China Machinery Industry Federation and 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: Fan Jin and Xu Gang. The previous versions of the standards replaced by this standard are: -GB/T4243-1984.
1 Scope
Morse taper shank long-edge machine reamer
This standard specifies the dimensions and marking examples of Morse taper shank long-edge machine reamer. This standard includes three tables:
Recommended diameters and corresponding dimensions in millimeters; recommended diameters and corresponding dimensions in inches; GB/T4243-2004
Dimensions in millimeters and inches divided by diameter. In addition, the length and cutting part diameter tolerances are also specified. This standard applies to high-speed steel Morse taper shank long-edge machine reamers with diameters greater than 6mm to 85mm. 2 Normative references
The clauses in the following documents become the clauses of this standard through reference in this standard. For any dated referenced documents, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For any undated referenced document, the latest version shall apply to this standard. GB/T1443 Self-clamping cone for machine tools and tool handles (GB/T1443-1996, eqvISO296:1991) GB/T4246 Special tolerances for reamers (GB/T4246-2004, ISO522:1975, IDT) 3 Interchangeability
When compiling the various dimension tables, consideration was given to ensuring that the dimensions expressed in millimeters and inches are as equal as possible. Therefore, the diameter range is further subdivided into a series of size segments. The limit values ​​of the metric diameter size segments are taken from the preferred number series and directly converted into imperial values. The metric and imperial lengths in the same diameter segment remain the same. However, the recommended diameters are different in the two measurement units, and the recommended diameter numbers are also different in the same diameter segment. 4 Tolerances
4.1 Cutting section
The diameter d is measured immediately after the cutting cone. For standard reamers, the tolerance of diameter d is m6. The diameter tolerance of reamers for machining holes with specific tolerances is designed according to GB/T4246. Appendix A of this standard gives the diameter tolerance of reamers for machining holes with H7, H8 and H9 grades.
4.2 Length tolerance
The length tolerance of reamer is in accordance with Table 1.
Table 1 Length tolerance
Total length L, cutting edge lengthbzxz.net
GB/T 4243—2004
For reamers with special tolerances, the length and shank size can be selected from adjacent larger or smaller segments, but the tolerance is in accordance with the provisions of Table 1.
Example:
For a special tolerance Morse taper shank long-edge machine reamer with a diameter of 15 mm, the length L can be 187 mm, l is 87 mm and a No. 2 Morse taper shank: or the length L can be 156 mm, l is 76 mm and a No. 1 Morse taper shank (see Table 4). 5 Dimensions
Morse taper shank
Morse taper shank long-edge machine reamer
Table 2 Recommended diameters and corresponding dimensions
Unit: mm
Morse taper shank number
（42）
（44)
Table 2 (continued)
Note: Dimensions in brackets should not be used as much as possible. Morse taper shank shall comply with the provisions of GB/T1443: L
Table 3 Recommended diameter and corresponding size
（13/52）
(15/%2）
GB/T4243—2004
Unit: mm
Morse taper shank number
Unit: inch
Morse taper shank number
GB/T 4243—2004
（1%.）
（1%)
(1%)
(1%)
(1%)
(1%)
Table 3 (continued)
Note: The dimensions in brackets should not be used as much as possible. Morse taper shank shall comply with the provisions of GB/T1443. L
11%.
Dimensions divided by diameter
Diameter range d
Length dimension
Unit is inch
Morse taper shank number
Taper shank number
Diameter range d
Note: Morse taper shank shall comply with the provisions of GB/T1443. Marking example
Table 4 (continued)
Length dimension
The Morse taper shank long-edge machine reamer with diameter d=10mm and tolerance m6 is: Long-edge machine reamer 10GB/T4243—2004The Morse taper shank long-edge machine reamer with diameter d=10mm for machining H8 grade precision holes is: 10H8GB/T4243—2004
Long-edge machine reamer
GB/T4243—2004
Taper shank number
GB/T4243—2004
Appendix A
(Normative appendix)
Table A.1 Tolerance of tool diameter for machining H7, H8 and H9 grade holes
Unit: mm
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