Button sharpening

• US 5,182,971 A
• Filed: 03/12/1992
• Issued: 02/02/1993
• Est. Priority Date: 02/14/1990
• Status: Expired due to Fees

• Current Assignee: Boast International Limited
• Original Assignee: Boast International Limited
• Inventors: Williams, David S.
• Primary Examiner(s): PARKER JR, ROSCOE
• Application Number:
  US07/849,879
• Time in Patent Office: 327 Days
• Field of Search: 76/108.2, 76/108.1, 76/108.4, 76/101.1, 76/5.1, 51/206 R, 51/288, 51/71, 51/72, 51/96, 51/97, 51/97 NC, 51/98 R
• US Class Current: 76/5.1
• CPC Class Codes: B24B 3/33 of drills for stone
• CPC Class Codes: E21B 10/52 with chisel- or button-type inserts

Abstract

A hardmetal drill bit button is restored by forming its head to a chisel shape. Various chisel shapes and a machine for the purpose are disclosed. Also disclosed are various kinds of grinding wheels for the purpose, and a method and means for simultaneously dressing the steel of the bit body.

Claims

1. A machine for restoring the buttons of a button bit, the machine comprising a grinding wheel with a V-groove at its periphery, means for locating and non-rotatably holding a button bit relative to the grinding wheel with a button which is to be restored in alignment with the periphery of the wheel, and means for causing relative movement to take place in one plane only between the button bit and the wheel such that the button is fed into the V-groove with the result that the head of the button is formed to a chisel shape.

2. A machine according to claim 1 comprising a bit holder provided at the end of a bit arm for holding the button bit in a non-rotatable manner, the bit arm being pivotable to move the button bit arcuately relative to the grinding wheel in the said one plane and without rotation of the button, to feed the relevant button into the V-groove at the periphery of the grinding wheel.

3. A machine according to claim 1 wherein said V-groove of said grinding wheel has a shape to grind the button head to a chisel shape having an included angle in the range 90°

to 130°

.

4. A machine according to claim 3 wherein said included angle is about 110°

.

5. A machine according to claim 3 wherein said V-groove has a sharp bottom, thereby to produce in the button head a chisel shape having a sharp apex.

6. A machine according to claim 3 wherein said V-groove has a rounded bottom, thereby to produce in the button head a chisel shape having a rounded apex.

7. A machine according to claim 3 wherein said V-groove has a bottom having a flat surface, thereby to produce in the button head a blunt chisel shape.

8. A machine according to claim 3 wherein said grinding wheel comprises a central section adapted to produce a chisel shape in the head of the button and outer sections between which said central section is located, said outer sections being adapted to remove material from the body of the drill bit at the same time as the chisel shape is produced in the head of the button.