GB/T 15054.2-2018Miniature screw threads - Part 2: Tolerances and limits of size (English PDF)

Foreword

GB/T 15054 "small thread" is divided into the following two parts.

--- Part 1. Teeth, series and basic dimensions;

--- Part 2. Tolerances and limit dimensions. This part is the second part of GB/T 15054. This part is drafted in accordance with the rules given in GB/T 1.1-2009. This part replaces GB/T 15054.4-1994 "small thread tolerance" and GB/T 15054.5-1994 "small thread limit size". Compared with GB/T 15054.4-1994 and GB/T 15054.5-1994, the main technical changes in this section are as follows:

--- Move the small thread tolerances and limit dimensions with a nominal diameter of 1mm and above to the appendix (see Appendix A, GB/T 15054.4- Chapter 3 of.1994, Chapter 3 of GB/T 15054.5-1994);

---Increase the "thread code" in the thread mark, and mark the position of the left-hand code "LH" before the tolerance band code Move to the tolerance band code (see Chapter 8, Chapter 4 of GB/T 15054.4-1994);

--- Remove the 5-level tolerance of the large diameter of the external thread (see

3.2 of GB/T 15054.4-1994);

---Remove the content of the coated thread tolerance band (see

3.4 of GB/T 15054.4-1994);

--- Remove the thread's preferred tolerance band content (see

3.5 of GB/T 15054.4-1994);

--- Increase the thread limit size of 3 tolerance zones (3G5, 3G6 and 4H6) (see Chapter 9);

--- Increase the thread inspection content (see Chapter 10 and Appendix B). This part is proposed and managed by the National Thread Standardization Technical Committee (SAC/TC108). This section drafted by: Zhejiang Changhua Auto Parts Co., Ltd., China Machine Productivity Promotion Center, Qifeng Seiko Technology Co., Ltd. the company. The main drafters of this section. Zhang Yiwei, Li Xiaobin, Chen Yuezhong, Zhang Jiansheng. The previous versions of the standards replaced by this section are.

---GB/T 195-1963;

1 Scope

GB/T 15054.2-2018 is the Chinese national standard on miniature screw threads - part 2: tolerances and limits of size, in the field of mechanical systems and components. The /T suffix marks it as a recommended standard: it is not compulsory by itself, but it becomes binding as soon as a contract, a tender or a customer specification calls it up - which in practice is how most foreign buyers meet it. It was issued on 14 May 2018 by the State Administration for Market Regulation; Standardization Administration of China, and has been in force since 1 October 2018. Classification: ICS 21.040.30, CCS J04. This page is published from the official record of the standard held by the Chinese standards administration: the identification, the dates, the classification and the issuing body are taken from there. The clause text, the tables and the numeric limits are in the document itself, which is delivered complete in English translation.

This part of GB/T 15054 specifies the tolerances, limit dimensions, marking and inspection of small threads. This section applies to general purpose small threads with a nominal diameter range of 0.3mm~1.4mm.

Note. The small thread (S) with a nominal diameter range of 1mm~1.4mm is different from the normal thread (M).

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article. Pieces. For undated references, the latest edition (including all amendments) applies to this document.

GB/T 14791 thread terminology

3 Terms and definitions

The terms and definitions defined in GB/T 14791 apply to this document.

4 Code

The following codes are applicable to this document. D internal thread basic diameter (nominal diameter) D2 internal thread basic diameter D1 internal thread basic diameter d Basic diameter of external thread (nominal diameter) D2 external thread basic diameter D3 external thread bottom diameter (on the design of the tooth) P pitch Lower deviation of EI internal thread diameter (basic deviation) Es Upper deviation of the external thread diameter (basic deviation) T tolerance TD2 internal thread diameter tolerance TD1 internal thread diameter tolerance Td external thread large diameter tolerance Td2 external thread diameter tolerance Td3 external thread bottom diameter tolerance

5 Tolerance zone position

Select the tolerance band position for each diameter according to Table 1. The tolerance band positions of the internal and external threads are shown in Figures 1 and 2, respectively.