FORD WD951-2001 MECHANICAL AND PERFORMANCE REQUIREMENTS OF CASE HARDENED THREAD ROLLING SCREWS《表面硬化的滚丝螺钉的机械和性能要求》.pdf
《FORD WD951-2001 MECHANICAL AND PERFORMANCE REQUIREMENTS OF CASE HARDENED THREAD ROLLING SCREWS《表面硬化的滚丝螺钉的机械和性能要求》.pdf》由会员分享,可在线阅读,更多相关《FORD WD951-2001 MECHANICAL AND PERFORMANCE REQUIREMENTS OF CASE HARDENED THREAD ROLLING SCREWS《表面硬化的滚丝螺钉的机械和性能要求》.pdf(5页珍藏版)》请在麦多课文档分享上搜索。
1、 WORLDWIDE FASTENER STANDARD Date: 2001-01-04 WD951 MECHANICAL AND PERFORMANCE REQUIREMENTS OF CASE HARDENED THREAD ROLLING SCREWS Printed copies are uncontrolled. Page 1 of 5 Copyright 2001, Ford Global Technologies, Inc. 1. SCOPE. This standard specifies the requirements for high performance case
2、hardened and tempered thread rolling screws that have performance capabilities beyond those normally expected of other types of tapping screws. It relates to screws with basic 60oscrew thread form, metric series, intended for parts up to and including 5mm nominal thread diameter only. For parts abov
3、e 5mm, WD 952 is recommended. Clause 3.4 defines thread-forming capability in steel up to a hardness of 150 HV and thickness equal to the screw diameter. The parameters of material hardness and thread engagement may be varied by analysis of joint requirements and it is therefore recommended that spe
4、cific applications be investigated to determine joint criteria. NOTE: Lubrication approved by Ford is permitted on parts to which this specification is applied unless otherwise specified. 1.1 REFERENCES. ISO 262 - ISO general purpose metric screw threads - Selected sizes for screws, bolts and nuts.
5、ISO 898/2 - Mechanical properties of fasteners - Part 2: Nuts with specified proof load values. ISO 5954 - Cold reduced carbon steel sheet to hardness requirements. ISO 6507 - Metallic materials - Hardness test - Vickers test. WSS-M99A3-A - Embrittlement Avoidance 2. MATERIALS. Screws shall be made
6、from cold heading quality fully killed steel wire; the following chemical composition is given for guidance only. Table 1. Chemical composition Analysis Composition Limits (% by Weight) Carbon Manganese Ladle 0.18 to 0.28 0.60 to 1.75 Check 0.16 to 0.30 0.54 to 1.81 3. MECHANICAL PROPERTIES. 3.1 HEA
7、T TREATMENT. Finished screws shall be case hardened and tempered in order to meet all the mechanical and performance requirements of this standard as detailed in Table 3. The case depth shall be as given in Table 4. The core hardness shall be 370 HV maximum, and the case hardness shall be 450 HV min
8、imum. However, the main criterion for acceptance is that the screws meet all the performance tests specified in this standard. WORLDWIDE FASTENER STANDARD Date: 2001-01-04 WD951 MECHANICAL AND PERFORMANCE REQUIREMENTS OF CASE HARDENED THREAD ROLLING SCREWS Printed copies are uncontrolled. Page 2 of
9、5 Copyright 2001, Ford Global Technologies, Inc. Table 2. Mechanical properties to be determined Criteria Clause Test Reference Referee Tests Case Hardness 3.1 4.2 Core Hardness 3.1 4.1 Case Depth 3.1 and Table 4 4.3 Torsional Strength 3.2 and Table 3 4.4 * Thread Forming Capability 3.4 4.5 Drive Te
10、st 3.4 4.6 * Table 3. Mechanical and performance requirements Nominal Screw Diameter (mm) Torsional Test Torque Nm Minimum 2 0.6 2.5 1.2 3 2.2 (3.5) 3.5 4 5.2 5 10.5 Table 4. Case depth Nominal Screw Case Depth (mm) Diameter (mm) Minimum Maximum 2 and 2.5 0.04 0.12 3 and (3.5) 0.05 0.18 4 and 5 0.10
11、 0.25 WORLDWIDE FASTENER STANDARD Date: 2001-01-04 WD951 MECHANICAL AND PERFORMANCE REQUIREMENTS OF CASE HARDENED THREAD ROLLING SCREWS Printed copies are uncontrolled. Page 3 of 5 Copyright 2001, Ford Global Technologies, Inc. 3.2 TORSIONAL TEST TORQUE. Minimum torsional test torque is specified in
12、 Table 3, when tested in accordance with Clause 4.4. Failure must not occur in the clamped threads. 3.3 DUCTILITY. There shall be no fracture at the head/shank intersection when a permanent deformation of 10ois induced between the plane of the underhead bearing face and a plane normal to the axis of
13、 the screw, when tested in accordance with Clause 4.5. The test shall be regarded as satisfactory even if a crack should appear in the first thread, provided that the head does not snap off. This test does not apply to countersunk head screws. 3.4 THREAD FORMING CAPABILITY. The screw shall, without
14、permanent deformation of its own thread when viewed at 10 x magnification, form a mating thread in a test plate in accordance with Clause 4.6. The thread formed by the screw in the test plate shall be capable of accepting a fastener threaded in accordance with ISO 262 tolerance class 6g and shall re
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