JB/T 9989.2-1999 This standard is a revision of ZB J41 003.2-87 "Thread Tolerances of Trapezoidal Thread Taps". During the revision, only editorial changes were made according to relevant regulations, and the technical content remained unchanged. This standard is part of the JB/T 9989 "Trapezoidal Thread Taps" series of standards. This series of standards includes the following three parts: JB/T 9989.1: Types and dimensions JB/T 9989.2: Thread tolerances JB/T 9989.3: Technical conditions This standard specifies the thread profile of trapezoidal thread taps and the limit deviations of their basic dimensions, and gives several explanations of the thread tolerances of trapezoidal thread taps in Appendix A (Standard Appendix). . This standard applies to trapezoidal thread taps (hereinafter referred to as taps) used for machining ordinary trapezoidal threads (according to JB/T 5796.1~5796.4-1986 "Trapezoidal threads"). The type tolerance zone of a tap is determined by the upper and lower deviations relative to the basic tooth profile. Tap threads are divided into three types: H7, H8, and H9. This standard was first published on July 1, 2009. JB/T 9989.2-1999 Trapezoidal thread taps Part 2: Thread tolerances JB/T9989.2-1999 Standard download decompression password: www.bzxz.net

ICS25.100.50
Machinery Industry Standard of the People's Republic of China
JB/T9989.1-9989.3-1999
Trapezoidal thread taps
1999-05-20 Issued
National Bureau of Machinery Industry
2000-01-01 Implementation
JB/T9989.2-1999
This standard is a revision of ZBJ410032-87 Trapezoidal thread taps (relative tolerances). When it is revised, only editorial modifications are made according to relevant regulations, and the technical content remains unchanged. This standard is part of the BT9989 "Trapezoidal thread taps" series of standards, which includes the following three parts BT9989.1-1999 Trapezoidal thread chain Part 1: Type and size BT9989.2-1999 Trapezoidal screw thread cans Part 2: Thread specifications BT9989.3-1999 Trapezoidal thread taps Part 3: Technical specifications This standard replaces 20J41003.2.-87 Appendix A of this standard.
This standard is proposed by the Enterprise Standardization Technical Committee and the responsible unit is: Ministry of Tools Research Institute. The main drafters of this standard are: Jiang Tigui, Wang Shangxiao, Lu Weiwei, Lan San, Wei Jianhua, Xia, ■Scope
Machinery Industry Standard of the People's Republic of China
Trapezoidal thread taps
Part 2: Thread tolerances
189589.2-1999
Generation J4.2-7
This standard specifies the limit deviation of the thread shape and basic size of trapezoidal thread taps, and gives some explanations on the thread tolerances of trapezoidal thread taps in the appendix (Appendix to the standard). This standard applies to trapezoidal thread (hereinafter referred to as thread chain) used for trapezoidal thread (conforming to GB/T57961-5796.41986 thread). The thread tolerance zone is determined by the upper deviation and deviation relative to the basic tooth type. The thread tolerance zone is divided into three types: H7, H8 and H9.
2 Available standards
The text contained in the following standards is quoted in this standard. The texts of the previous standard are not all valid when this standard is published. All standards will be revised. The use of this standard can help all parties to discuss the possibility of using the latest version of the following standard: GR/T5796.1.198G GR5796.2—19R Trapezoidal thread diameter and spacing series ≤796.3—1986 Trapezoidal thread basic size BT5796.41986 Trapezoidal thread tolerances 3 Thread tooth type and size limit deviations 3. The thread tooth type is as shown in the figure, and the size limit deviation is given in Table 1. ... 4
10-333
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JB/T9989.2—1999
Middle diameter 4, tolerance zone
+240, +320
240: +30D
+2 including 4
: +285
+3551+249
Li's belt
Measurement H7
Number of teeth,
± 15±2D
± 26f
"The diameter of the thread is the minimum diameter of the thread gland, and the final diameter should not exceed the minimum diameter of the nut. The diameter, pitch diameter, minor diameter or main size of the thread pin and the size of the trapezoidal internal thread are the same. Tooth half angle
± 15s
+ + 15 + 2Www.bzxZ.net
±25110
3.2 The tolerance of the pitch diameter of multi-thread trapezoidal thread is based on the tolerance of the pitch diameter of the single-thread thread and multiplied by a coefficient according to the number of threads. The coefficients for different numbers of threads are given in Table 2.
Mosquito thread
Tap pitch diameter
JBrr9989.2—199y
Appendix A
Appendix to the standard!
About tap twisting tolerance A1.1 The values ​​of the wire mean diameter tolerance T, lower deviation and upper deviation are calculated according to the formula (& grade + diameter tolerance). The figure shows the relationship between the wire mean diameter tolerance T, lower deviation and upper deviation. The wire mean diameter tolerance T, lower deviation and upper deviation are calculated according to the formula (& grade + diameter tolerance). The wire mean diameter tolerance T, lower deviation and upper deviation are calculated according to the figure (A1). A1.2
The thread of the original tooth type is in the (,-, position
A1.3 The processing model diagram suitable for the thread is given in Table A2. Table A2
Thread tolerance band
Applicable internal thread tolerance band
Due to the factors that affect the tapping diameter, such as the properties of the tapping material, machine tool conditions, final assembly card, cutting speed, cold cutting wave type, etc. Therefore, the internal thread tolerance band that can be processed by the various tolerance band taps listed in Table A2 can only be used as a reference for the design of these pins. The user can select the most appropriate thread pin within the range listed in this standard according to production experience or through experiments under certain conditions.
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