High performance thread forming screw

A technology for locking screws and screws, applied in the directions of screws, threaded fasteners, connecting components, etc., can solve the problems of high process cost and time-consuming

Inactive Publication Date: 2009-08-05
ACUMENT INTPROP LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

These structures / methods require additional operations, hardware and time, resulting in a more costly and time-consuming process

Method used

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  • High performance thread forming screw
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Embodiment Construction

[0015] While the invention can be employed in various forms of embodiments, one embodiment has been shown and described in detail herein, it being understood that the description is illustrative of the principles of the invention and is not intended to limit the invention as described herein. and describe the range.

[0016] One aspect of the invention relates to a fastener, such as a self-tapping screw, at least a portion of which has a surface hardness of HRC56. Another aspect relates to a method of hardfacing a fastener such as a self-tapping screw such that at least a portion thereof has a surface hardness of HRC56. While the method can be used with many screws, US Patent No. 3935,785 discloses a screw to which methods according to embodiments of the present invention can be used and is hereby incorporated by reference in its entirety.

[0017] as in this application figure 1 As shown in the aforementioned patent, the screw 10 includes a head 12 and a threaded shank 14 e...

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Abstract

The invention provides a thread forming screw and a method for forming the same. A thread forming screw having a minimum surface hardness of HRC 56. The screw can form threads in a workpiece having a surface hardness which exceeds HRC 23. A method of surface hardening a screw includes carbon enriching the screw to at least a 0.48% carbon level, and then quenching the screw. Then, the screw is tempered such that the surface hardness does not exceed the core hardness by more than 3 Rockwell C points, and both the surface and core are at a Rockwell C33-C39 hardness. Subsequently, the point is induction hardened, and the screw is quenched again. The screw is again tempered such that the lead threads and the first 3-4 full threads are at a Rockwell C56 minimum hardness, preferably to a depth of at least 0.008 inches, and the core of the fastener is at Rockwell C33-C39 hardness. Finally, a finish is applied.

Description

technical field [0001] The present invention relates generally to a self-tapping screw and a method of forming the same, and more particularly to a fastener, such as a self-tapping screw, at least a portion of which has an HRC56 (Rockwell hardness class C) and relates to a method of forming such self-tapping locking screws. Background technique [0002] It is now proposed in the industry that self-tapping locking screws can be cold-extruded to form threads in workpieces with a Rockwell hardness of C23 and below. Likewise, self-tapping screws are now hard enough to form threads in such workpieces. However, there are still some applications where it is desired that self-tapping screws can form threads in workpieces with a hardness exceeding HRC23. For example, after forming a high strength low alloy (HSLA) material, such as by punching a hole in the material, the hardness near the hole can reach and exceed Rockwell C40. [0003] Conventional self-tapping screws are not hard...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F16B25/00
Inventor 大卫·R·普莱斯加里·沙特克
Owner ACUMENT INTPROP LLC
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