JB/T 7981-1999 JB/T 7981-1999 Thread Sample JB/T7981-1999 Standard Download Decompression Password: www.bzxz.net

JB/T 7981--1999
This standard is revised on the basis of JB/T7981-95 "Thread Sample". This standard is consistent with the technical content of JB/T7981-95, and has only been re-edited according to relevant regulations. Appendix A of this standard is the appendix of the standard.
This standard replaces JB/T7981--1999 from the date of implementation.
This standard is proposed and managed by the National Technical Committee for Standardization of Measuring Tools and Instruments. The responsible drafting unit of this standard: Shanghai Xinyu Instrument Factory. This standard was first issued as JB2210--77 in 1977, revised to GB9055--88 in April 1988, and adjusted to JB/T7981---95 in April 1996.
1 Scope
Standard of the Machinery Industry of the People's Republic of China
Template
Screw thread template
This standard specifies the type and size, technical requirements, marking and packaging of thread templates. JB/T7981-1999
Replaces JB/T7981-95
This standard is applicable to thread templates used to test ordinary thread pitch and imperial thread pitch (teeth/inch). 2 Definitions
This standard adopts the following definitions.
2.1 Thread template
With a certain pitch and tooth shape, and meeting certain accuracy requirements, it is used as a standard for measuring similar threads as a thread standard.
3 Type and size
3.1 The type of the ring thread template is shown in Figure 1. Sample
Screw or nail
3.2 The pitch size series of complete sets of thread samples are shown in Table 1. Approved by the State Machinery Industry Bureau on May 20, 1999, protection plate
Implementation on January 1, 2000
Pitch types
Pitch size series
Sample number
JB/T7981—1999
Ordinary thread pitch
0.40,0.45,0.50,0.60,0.70.0.75,0.80,1.00.1.25,1.50,1.75,2.00,2.50,3.00.3.50,4.00.4.50,5.00,5.50.6.0020
3.3 The thickness of the thread sample is 0.5mm.
4 Technical requirements
4.1 The surface of the thread template should not have defects that affect the performance. British thread pitch
Threads/inch
28,24,22.20,19,18,16,14,12,11.10.9+8,7,6,5,4.5,4
4.2 The connection between the thread template and the protective plate should ensure that the template can be easily replaced, and the template should be able to rotate smoothly around the screw or rivet axis without sticking or loosening.
4.3 The set of thread templates should be arranged in the order of pitch size series from small to large. The thread template should be made of 45# cold-rolled strip steel or high-quality carbon steel. 4.4
The hardness of the measuring surface of the thread template should not be less than 230HV. 4.5
The surface roughness Ra value of the measuring surface of the thread sample is 1.6um. 4.6
The tooth profiles and sizes of the common thread sample and the imperial thread sample are shown in Figure 2 and Table 2 and Table 3 respectively. 4.7
Pitch p
Basic size
Limit deviation
Basic tooth profile angle
Limit deviation of tooth profile half angle α/2
+50″
Tooth crest and tooth root width
Thread working
Part length
Pitch P
Basic size
Limit deviationbzxZ.net
Pitch P| |tt||Basic tooth profile angle
JB/T7981—1999
Table 2 (end)
Limit deviation of tooth profile half angle α/2
±30°
±20°
Basic tooth profile angle
Limit deviation of basic size of number of teeth per inch
Limit deviation of tooth profile half angle α/2
|tt||Thread top and thread bottom width
Thread top and thread bottom width
±30″
±20″
Screw Thread work
Partial length
Thread work
Partial length
5. Marking and packaging
5.1 The protective plate of the complete set of thread templates shall be marked with: a) manufacturer's name or registered trademark;
JB/T7981--1999
b) product name (ordinary thread template or British 55° thread template). The basic pitch size (ordinary thread template) or the number of teeth per inch (British thread template) shall be marked on each template of the complete set of thread templates. 5.2
5.3 The thread sample packaging box should be marked with: a) manufacturer's name or registered trademark;
b) product name (ordinary thread sample or British 55° thread sample); c) standard number of this standard;
d) date of manufacture.
5.4 The thread sample should be rust-proofed and properly packaged before packaging, and should not be damaged during transportation due to poor packaging. The thread sample should be accompanied by a product certificate that has been verified to meet the requirements of this standard. The product certificate should have the standard number of this standard and the date of manufacture.
JB/T 7981: -1999
Appendix A
(Standard Appendix)
Verification Method of Thread Samples
This appendix specifies the verification method of thread samples for production and factory verification. A1 Appearance and Completeness Verification
Inspect the appearance quality visually according to 4.1. Check the pitch size series of the complete set of thread samples according to Table 1. A2 Interaction Verification
Inspect by hand that each sample can smoothly rotate around the screw or rivet axis without any jamming or loosening. Each sample should be easy to replace. A3 Hardness Verification
Inspect according to 4.5 using the Vickers hardness test.
A4 Surface Roughness Verification
Inspect by comparison using the surface roughness comparison sample according to 4.6. A5. Calibration of pitch, tooth top (tooth bottom) width and tooth profile half angle. Aim the Mi-shaped lens of the tool microscope at 0 or 180°, and then adjust the position of the inspected sample on the workbench so that the tooth top connection line coincides with the horizontal (or vertical) division line of the Mi-shaped lens. a) Pitch: Calibration should be carried out on the entire length of the threaded working part of the inspected sample. During calibration, move the longitudinal (horizontal) differential cylinder of the workbench so that the intersection of the Mi-shaped line of the Mi-shaped lens coincides with the corresponding positions on the two adjacent teeth of the inspected section. The difference between the corresponding differential cylinder indications (taking the absolute value) and the nominal length is the pitch deviation; b) Tooth top (tooth bottom) width: At least two tooth profiles should be calibrated on the inspected sample. During calibration, move the longitudinal (horizontal) differential cylinder of the workbench. Make the intersection of the M-shaped line of the M-shaped line lens coincide with the two ends of the top (bottom) of the tested tooth profile (the intersection of the two tooth side surfaces and the tooth top or tooth bottom), and the difference between the corresponding differential cylinder indications is the actual width of the tooth top (tooth bottom): c) Tooth profile half angle: At least two tooth profiles should be calibrated on the tested sample. During the calibration, adjust the angle measuring lens so that it coincides horizontally (or vertically) with any tooth side surface of the tested tooth profile contour, and the corresponding indication of the angle measuring lens is the actual value of the tooth profile half angle of the tested sample. 217
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