Manufacturing method of austenitic stainless steel self-tapping and self-drilling screw

• US 5,205,466 A
• Filed: 07/15/1992
• Issued: 04/27/1993
• Est. Priority Date: 07/15/1992
• Status: Expired due to Term

• Current Assignee: Tzeng Chieh-Chang
• Original Assignee: Chieh-Chang Tzeng
• Inventors: Ker, Yao-Tin
• Primary Examiner(s): Ramsey, Kenneth J.
• Application Number:
  US07/913,353
• Time in Patent Office: 286 Days
• Field of Search: 470/11, 470/17, 148/529, 148/534, 148/211, 148/213, 228/176, 228/232, 228/263.15, 228/125
• US Class Current: 228/125
• CPC Class Codes: B23P 15/00 Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
• CPC Class Codes: C21D 2251/00 Treating composite or clad material
• CPC Class Codes: C21D 9/0093 for screws; for bolts
• CPC Class Codes: F16B 25/0094 the screw being assembled or manufactured from several components, e.g. a tip out of a first material welded to shaft of a second material
• CPC Class Codes: F16B 25/103 by means of a drilling screw-point, i.e. with a cutting and material removing action
• CPC Class Codes: F16B 33/008 Corrosion preventing means
• CPC Class Codes: F16B 35/00 Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws F16B33/008 takes precedence; joining sheets or plates using screws with two separate threads F16B5/0275; using screws with adjustment sleeves F16B5/0283; thread cutting screws F16B25/00

Abstract

This invention is a manufacturing method of Austenitic stainless steel self-tapping and self-drilling screw. It uses low carbon steel or low carbon alloy steel and forges or cuts it into a round rod with a shoulder, non-threaded bolt, and drilling end portion. After it is carburized and properly heat-treated, it will be welded together with an Austenitic stainless steel round rod which has a non-threaded bolt. And then the welded flush and shoulder will be cut so that a non-carburized hardened area in a proper width can be formed. Lastly it is threaded and quenched so as to manufacture a screw whose head and threaded stem joint are high corrosion-resistance and whose carburized drilling end portion has a high self-tapping and self-drilling function.

Claims

1. A method of manufacturing an austenitic stainless steel self-tapping and self-drilling screw formed from low carbon or low carbon alloy steel including the steps of:

(a) forming a low carbon or low carbon alloy steel rod having a rod shoulder section, a rod non-threaded bolt section and a rod drilling end section;

(b) carburizing and heat treating said rod to a predetermined carburization depth to provide a carburized portion of said rod;

(c) establishing an austenitic stainless steel rod having a head section and a non-threaded bolt section;

(d) welding said austenitic stainless steel non-threaded bolt section to said rod shoulder section in aligned relation thereto forming a weld flash;

(e) removing said rod shoulder section and said weld flash to provide a non-carburized section of said rod;

(f) threading said rod non-threaded bolt section and said austenitic stainless steel rod non-threaded bolt section.

2. The method of manufacturing said austenitic stainless steel self-tapping and self-drilling screw as recited in claim 1 wherein the step of forming said low carbon or low carbon alloy steel rod includes the step of:

establishing said rod shoulder section having a diameter approximately equal to or larger than the summation of an outer diameter of said rod non-threaded bolt section and twice said carburization depth, said rod shoulder section having a width approximately equal to or larger than the summation of a width of a welding heat affected zone and twice said carburization depth.

3. The method of manufacturing said austenitic stainless steel self-tapping and self-drilling screw as recited in claim 1 wherein said rod non-carburized portion has a width approximately equal to or larger than a width of a welding heat affected zone.

4. The method of manufacturing said austenitic stainless steel self-tapping and self-drilling screw as recited in claim 1 wherein said rod shoulder section is contoured into a predetermined cross-sectional geometric configuration.