This standard specifies the product classification, technical requirements, test methods, acceptance inspection, marking and packaging of non-metallic insert hexagonal lock nuts (hereinafter referred to as lock nuts) with thread specifications of M27, performance levels of 8 and 10, and grade B. This standard is applicable to non-metallic insert hexagonal lock nuts for scraper conveyors and scraper transfer machines in coal mines. MT/T 187.8-1991 Scraper conveyor fasteners non-metallic insert hexagonal lock nuts MT/T187.8-1991 Standard download decompression password: www.bzxz.net

Coal Industry Standard of the People's Republic of China
Fasteners for Scraper Conveyors
Non-metallic Insert Hexagonal Lock Nuts
Subject Content and Scope of Application
MT/T 187.8-91
This standard specifies the product classification, technical requirements, test methods, acceptance inspection, marking and packaging of non-metallic insert hexagonal lock nuts (hereinafter referred to as lock nuts) with thread specification M27, performance grades 8 and 10, and grade B. This standard is applicable to non-metallic insert hexagonal lock nuts for scraper conveyors and scraper transfer machines in underground coal mines. 2
Referenced standards
GB196 Basic dimensions of common threads (diameter 1 ~ 600mm) GB197 Tolerances and fits of common threads (diameter 1 ~ 355mm) GB3098.2 Mechanical properties of fasteners Nuts
GB3103.1 Tolerances of fasteners Bolts, screws and nuts GB5779.2 Surface defects of fasteners General requirements for nuts GB 90 Acceptance inspection, marking and packaging of fasteners 3 Product classification
3.1 The type and size of the product are shown in Figure 1 and Table 1. Refer to Appendix A for manufacturing drawings. 15°~30°
Approved by the Ministry of Energy of the People's Republic of China on September 20, 1991 and implemented on January 1, 1992
Thread specification D
3.2 Marking example:
MT/T 187. 8---91
Coarse pitch ordinary thread, thread specification D=27mm, performance level 8, Class B non-metallic insert hexagonal locking nut. Nut: MT27-8
3.3 Marking description
Nut MT M27-8
Performance level
Product specification
Standard code
-Product name
4 Technical requirements
4.1 Lock nuts shall comply with the provisions of this standard and be manufactured according to drawings and technical documents approved by the prescribed procedures. 4.2 The performance grade of the locking nut is 8 and 10, and it shall meet the mechanical performance requirements specified in GB3098.2. 4.3 The locking nut shall be subjected to surface galvanized passivation treatment. s
4.4 The non-metallic insert material of the locking part of the locking nut is nylon, and it is recommended to be made of nylon 66 or nylon 1010. When the bolt is screwed into the nut, nylon cutting is not allowed in the nylon insert, but excess nylon material is allowed to extrude out of the screw hole. 4.5 The locking torque of the locking nut shall refer to Appendix A and be agreed upon by the supply and demand parties. 4.6 The threaded part of the locking nut shall meet the following requirements: a.
The basic size of the thread shall be in accordance with the provisions of GB196;
The thread tolerance shall be in accordance with the provisions of GB197, and the thread tolerance is 6H; the maximum allowable value of the thread surface roughness R. is 6.3um. The marking system for the performance grade of the locking nut shall be implemented in accordance with the provisions of GB3098.2. 4.74
The surface defects of locking nuts shall comply with the provisions of GB5779.2. The tolerance of locking nuts shall comply with the provisions of GB3103.1, and the product grade is Class B. 4.9
5 Test methods
5.1 The mechanical performance test items and test methods of the product shall comply with the provisions of GB3098.2. 5.2 The locking performance test method of the product can be a torque wrench test or agreed upon by the supply and demand parties. 6 Acceptance inspection, marking and packaging
6.1 The products shall be inspected by the quality inspection department of the manufacturer. The manufacturer shall ensure that each batch of products leaving the factory meets the requirements of this standard and is accompanied by a product certificate.
6.2 The acceptance inspection, marking and packaging of the products shall comply with the provisions of GB90. 228
MT/T187.8—91
Appendix A
Manufacturing drawings and tightening torques of locking nuts (reference parts)
A1 The manufacturing drawings of locking nuts are shown in Figure A1. Locking nut mother
90°~1209www.bzxz.net
A2 The tightening torques of locking nuts are shown in Table A1. Table A1
Tightening torque, N·m
Thread specifications
Additional instructions:
First screw-in
Performance level 8
First screw-out
This standard was proposed by the China Coal Research Institute. This standard is under the jurisdiction of the Taiyuan Branch of the China Coal Research Institute. This standard was drafted by the Harbin Coal Mine Machinery Research Institute. The main drafter of this standard is Cong Peijian.
Fifth time to unscrew
First time to insert
Nylon insert
Performance grade 10
First time to unscrew
Fifth time to unscrew
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