MANUFACTURE OF SAW BLADES

• US 3,685,373 A
• Filed: 11/02/1970
• Issued: 08/22/1972
• Est. Priority Date: 11/12/1969
• Status: Expired due to Term

• Current Assignee: Cyril Leslie Norfolk
• Original Assignee: Cyril Leslie Norfolk
• Inventors: Norfolk, Cyril Leslie
• Primary Examiner(s): Stickney, Bernard
• Application Number:
  US05/086,064
• Time in Patent Office: 659 Days
• Field of Search: 76/101,112 219/121P,77
• US Class Current: 76/112
• CPC Class Codes: B23D 65/00 Making tools for sawing machines or sawing devices for use in cutting any kind of material
• CPC Class Codes: B23K 31/025 Connecting cutting edges or the like to tools; Attaching reinforcements to workpieces, e.g. wear-resisting zones to tableware

Abstract

Bimetallic blades, particularly saw blades, are made by edge welding together, by microplasma welding, two strips of steel, and converting the welded composite strip to blade form.

Claims

1. A method of manufacturing a blade utilizing microplasma welding to weld together in edge-to-edge relation a prefabricated strip of cutting tool steel and a prefabricated strip of backing steel, comprising the steps of (a) directing a plasma stream at the strips in a direction contained in the plane of the edge surfaces of the strips to be welded, and (b) shielding the plasma stream by means of a gaseous stream of a mixture of hydrogen and argon, and (c) converting the strip of cutting tool steel into a blade.

2. A method according to claim 1 wherein a stream of shielding gas is blown at the strips from the side thereof opposite to the side receiving the plasma stream to prevent oxidation at said opposite side.

3. A method according to claim 1 wherein the gaseous stream consists substantially of 15 percent by volume hydrogen and 85% by volume argon.

4. A method according to claim 1 wherein the welded strip is annealed as a step immediately after the microplasma welding step.

5. A method according to claim 1 wherein, after the microplasma welding step, the cutting edge of the blade is shaped and thereafter the whole blade is subjected to a high-temperature heat-treatment suitable for the steel of the cutting edge portion, cooled relatively slowly to a temperature below 800* C. and then tempered at a temperature of 500*-650* C. for a time sufficient to give the remainder of the blade the desired strength and resilience.

6. A method according to claim 5 wherein the tempering is carried out for 2 1/2 to 3 hours.

7. A method according to claim 5 wherein the high temperature heat treatment is carried out at 1,240*-1,280* C. for 45-60 seconds.

8. A method according to claim 1 which includes the steps of welding a strip of steel which is to form a remainder of blade portion, by microplasma arc welding, to each side of a strip of high-speed steel suitable for forming a cutting portion of a blade, and then slitting the strip of high-speed steel centrally.

9. A method according to claim 1 wherein teeth are formed on a cutting portion to form a saw blade.