Abrasive wheel

• US 4,977,709 A
• Filed: 05/19/1989
• Issued: 12/18/1990
• Est. Priority Date: 05/19/1989
• Status: Expired due to Term

• Current Assignee: Uniroc AB
• Original Assignee: Inovac AB
• Inventors: Siden, Jan
• Primary Examiner(s): Schmidt, Frederick R.
• Assistant Examiner(s): RACHUBA, MAURINA T
• Application Number:
  US07/354,414
• Time in Patent Office: 578 Days
• Field of Search: 51/206 NF, 51/206 R, 51/373, 51/127, 51/105 EC, 51/105 R, 51/34 R, 51/34 C, 51/34 H, 51/50 R, 76/52, 76/108 A
• US Class Current: 451/541
• CPC Class Codes: B24B 19/26 for grinding workpieces with arcuate surfaces, e.g. parts of car bodies, bumpers or magnetic recording heads grinding of spherical surfaces in general B24B11/00, of optical surfaces on lenses or surfaces of similar shape on other work B24B13/00
• CPC Class Codes: B24B 3/33 of drills for stone
• CPC Class Codes: B24D 5/02 Wheels in one piece
• CPC Class Codes: B24D 7/18 Wheels of special form

Abstract

An abrasive wheel for grinding the cutting pins of a button-type drilling bit in a grinding machine of the kind provided with a rotatable holder for fixating the pins of the bit in a grinding position and for rotating thus fixated pins. The machine also includes a spindle on which the abrasive wheel can be mounted in a given position. The spindle/holder is linearly movable in a plane which extends through and is contained by the respective rotational axes of the holder and the spindle and in a direction parallel with the rotational axis of the spindle. The abrasive wheel includes circular flange parts which embrace a profiled groove therebetween. To enable cutting pins to be ground to an obtuse tip-profiled shape with the aid of such an abrasive wheel, the profiled groove, when seen in cross-section, is formed symmetrically around a line which intersects the rotational axis of the abrasive wheel at an angle whose complementary angle is equal to the angle of inclination of the spindle. The inward part of the profiled groove is widened symmetrically in relation to a predetermined transverse measurement and presents at least the same widening along the whole of it cross-section, upto the location of an outer limiting line, where the groove has a width or a breadth which is greater than the diameter of the pin for which the abrasive wheel is intended.

Claims

1. An abrasive wheel for grinding a tip of a hard metal pin of a button-studded drilling bit, to an obtusely profiled shape in an annular tapered band having an axially outer, smaller diameter and an axially inner, larger diameter, in a grinding machine having:

a rotatable holder in which the hard metal pin is disposed at a grinding position and rotated about a holder rotational axis for rotating the hard metal pin while the tip of the hard metal pin is being ground by an abrasive wheel; and

a driven spindle on which, in use, the abrasive wheel is disposed at a grinding position and rotated about a spindle rotational axis for rotating the abrasive wheel while the tip of the hard metal pin is being ground by the abrasive wheel;

at least one of the holder and spindle being linearly reversibly movable along said spindle rotational axis, in a plane containing both said rotational axes;

the spindle rotational axis being inclined from perpendicularity to the holder rotational axis, by an acute angle α

;

said abrasive wheel comprising;

a body which is rotationally symmetrical about an abrasive wheel rotational axis which, in use, coincides with said spindle rotational axis, said body including two circumferentially extending, radially outwardly projecting flange portions which sandwich between them a circumferentially extending, radially outwardly opening groove portion;

said groove portion having a surface profile which, in longitudinal cross-section of said abrasive wheel, is symmetrical about a line of symmetry which intersects said abrasive wheel rotational axis at an angle which is equal in magnitude to said angle α

;

said surface profile including a radially innermost base segment, two axially opposite radially outer segments having respective radially outer ends, and two axially opposite intermediate segments extending between axially opposite ends of said base segment and respective ones of said radially outer segments;

said surface profile being radially outwardly generally concave and flaring in width from said axially opposite ends of said base segment towards said radially outer ends of said radially outer segments;

said base segment being shorter transversally of said line of symmetry than the magnitude of said axially outer, smaller diameter of said obtusely profiled shape of said hard metal pin, and said two radially outer ends of said radially outer segments of said surface profile being located further apart transversally of said line of symmetry, than the magnitude of said axially inner, larger diameter of said obtusely profile shape of said hard metal pin.

2. A grinding machine for grinding a tip of a hard metal pin of a button-studded drilling bit, to an obtusely profiled shape in an annular tapered band having an axially outer, smaller diameter and an axially inner, larger diameter, comprising:

a rotatable holder in which the hard metal pin is disposed at a grinding position and rotated about a holder rotational axis for rotating the hard metal pin while the tip of the hard metal pin is being ground by an abrasive wheel;

an abrasive wheel; and

a driven spindle on which, in use, the abrasive wheel is disposed at a grinding position and rotated about a spindle rotational axis for rotating the abrasive wheel while the tip of the hard metal pin is being ground by the abrasive wheel;

at least one of the holder and spindle being linearly reversibly movable along said spindle rotational axis, in a plane containing both said rotational axes;

the spindle rotational axis being inclined from perpendicularity to the holder rotational axis, by an acute angle α

;

said abrasive wheel comprising;

a body which is rotationally symmetrical about an abrasive wheel rotational axis which, in use, coincides with said spindle rotational axis, said body including two circumferentially extending, radially outwardly projecting flange portions which sandwich between them a circumferentially extending, radially outwardly opening groove portion;

said groove portion having a surface profile which, in longitudinal cross-section of said abrasive wheel, is symmetrical about a line of symmetry which intersects said abrasive wheel rotational axis at an angle which is equal in magnitude to said angle α

;

said surface profile including a radially innermost base segment two axially opposite radially outer segments having respective radially outer ends, and two axially opposite intermediate segments extending between axially opposite ends of said base segment and respective ones of said radially outer segments;

said surface profile being radially outwardly generally concave and flaring in width from said axially opposite ends of said base segment towards said radially outer ends of said radially outer segments;

said base segment being shorter transversally of said line of symmetry than the magnitude of said axially outer, smaller diameter of said obtusely profiled shape of said hard metal pin, and said two radially outer ends of said radially outer segments of said surface profile being located further apart transversally of said line of symmetry, than the magnitude of said axially inner, larger diameter of said obtusely profiled shape of said hard metal pin.