US3739529A - Machine for the sharpening of impact rock drills with chisel cutting edges - Google Patents

Abstract

A machine for sharpening of impact rock drills having a number of radially directed chisel cutting edges around the axis of the drill crown comprising a grinding wheel with a double-conically shaped peripheral surface and a holding chuck for the drill during the sharpening operation, said grinding wheel being mounted on a horizontal shaft and the chuck being guided in a bidirectional grinding movement.

Description

United States Patent 1191 Lundberg June 19, 1973 MACHINE FOR THE SHARPENING 0F 2,275,483 3 1942 Parker 51/219 R UX IMPACT ROCK DRILLS WITH CHISEL 2,424,470 7/1947 Kronwa1l..... 51/219 R X 2,847,800 8/1958 Ingersoll 51/219 R X CUTTING EDGES 3,490,884 1/1970 Brierley 51/219 R x Inventor: Biirje Oskar Lundberg, Tyreso,

Sweden Assignee: AB Grindex, Handen, Sweden Filedr June 25, 1971 Appl. No.: 157,041

[30] Foreign Application Priority Data June 26, 1970 Sweden 8904/70 [52] US. Cl. 51/92 R, 51/219 [51] Int. Cl B24b 3/33 [58] Field of Search 51/92 R, 93, 219 R,

[56] References Cited UNITED STATES PATENTS 1,750,956 3/1930 Flanders 51/92 R Primary ExaminerDonald G. Kelly Azromey-David H. Semmes wheel with a double-comically shaped peripheral surface and a holding chuck for the drill during the sharpening operation, said grinding wheel being mounted on a horizontal shaft and the chuck being guided in a bidirectional grinding movement.

4 Claims, 2 Drawing Figures PATENIEU 9 3. 739.529

L INVENTOR BORJE OSKAR LUNDBERG g g MAM/M l5 ATTORNEY MACHINE FOR THE SHARPENING OF IMPACT ROCK DRILLS WITH CHISEL CUTTING EDGES The present invention relates to a machine for the sharpening of impact rock drills with a plurality of radially directed chisel cutting edges distributed around the axis of the drill crown, comprising a motor-driven grinding wheel formed by two frusto-conical surfaces meeting at a plane, and a chuck positioned with its axis in said plane through the grinding wheel for securely holding the drill crown or the drill shank, during the sharpening of the drill.

The object of the present invention is to provide such a sharpening machine by means of which impact rock drills of the kind defined above can be sharpened accurately, independent of the diameter of the grinding wheel which is variable according to wear.

According to the present invention, a machine for sharpening of impact rock drills having a number of radially directed chisel cutting edges distributed around the axis of a drill crown, comprises a motor-driven grinding wheel with a peripheral surface defined by two intersecting frusto-conical sections and a chuck having an axis located in the plane of the maximum perimeter of the grinding wheel for securely holding the drill crown and a drill shank during the sharpening, said grinding wheel being mounted on a shaft, which rotates but is otherwise fixed during the sharpening, and said chuck being guided on one hand for a reciprocating grinding movement in a first direction parallel with an intersection line in said plane of the grinding wheel between planes through adjacent cutting flanks of the tool, and on the other hand for a feeding movement in a second direction perpendicular to said direction and also lying in said plane of the grinding wheel.

The present invention will now be described more closely with reference to the accompanying drawings, which illustrate one embodiment of a sharpening assembly according to the present invention.

FIG. 1 shows the assembly in a side view and partly in a vertical cross section, while FIG. 2 is a view perpendicular thereto, seen in the direction of the arrows Il-ll in FIG. I.

In the embodiment illustrated on the drawings the grinding wheel is supported free-hanging on the horizontal shaft of a pneumatic motor 12. The latter is mounted on a support 14, which is built on a base plate 15.

Laterally of the sharpening assembly 10, 12 a support 16 is built on the base plate 15 having an upper support surface inclined downwardly towards the base of support 14. The support 16 carries two fixed guide rods 18 in sleeve-shaped members 17, said guide rods being located at opposite sides of an imaginary vertical plane through the maximum perimeter of the grinding wheel 10. The guide rods are parallel to said plane and with each other. On the fixed guide rods 18 two guide sleeves 19 are positioned between the fixture members 17, said guide sleeves 19 being substantially shorter than the distance between the fixture sleeves. The two guide sleeves are connected with each other to form a unit by means of a cross beam, not shown. Over the guide sleeves l9 fixed dust protection sleeves 20 are threaded, and in which reduced ends of the guide sleeves 19 are received in a piston-like manner.

On each of the guide sleeves 19 a guide rod 22 is securely mounted in a laterally extending fixture sleeve 21, the axis of said guide rod 22 being arranged at a right angle with the axis of the corresponding fixed guide rod 18 and being located in a plane, which is perpendicular to the base plate 15. On each of guide rods 22 one of two axially movable guide sleeves 23 is provided, whch are rigidly connected with each other by means of a cross beam, not shown. Said cross beam carries a chuck 24 in a vertical plane through the grind ing wheel, the chuck being pneumatically operated, for clamping the drill shank 25 in a horizontal position in the imaginary vertical plane containing the maximum perimeter of the grinding wheel. In the case of a machine for the sharpening of drills with three cutting edges the jaws of the chuck 24 are conveniently formed so that they hold the hexagonal drill steel in defined rotational positions, whereby a correct orientation of the cutting edges during the sharpening is secured. Dust protection sleeves 26 are fixedly supported by the fixture sleeves 21, and the lower ends of guide sleeves 23 fit telescopically at their lower ends into sleeves 26.

For the displacement of the drill chuck 24 and hence of the drill shank 25 reciprocally in a direction parallel to the axes guide rods 22, a pneumatic cylinder 27 is provided, and for the displacement of the chuck in a direction towards and away from the grinding wheel 10 in a direction parallel to the axes of the fixed guide rods 18, a feed screw with a hand wheel 28 is provided. The

' amount of feed can be read on a rotable scale ring 29,

which is lockable in a desirable z-ero position relative a scale line on the hand wheel 28.

On modern impact rock drills with hard metal cutting edges, for which the grinding wheel of the present in vention is primarily intended, the cutting edges have flat flank surfaces, which are joined in a common edge. The planes through mutually adjacent flank surfaces associated with two mutually adjacent cutting edges intersect each other along a straight line, which forms an acute angle a with the axis of the drill head or the drill shank. The reciprocal movement relative the grinding wheel must evidently be performed in a straight line, which is parallel with the intersection line between the planes through the cutting flanks, which intersect each other. This means that the guide rods 22 must form the angle -a with the axis of the drill head or the drill shank. In the sharpening machine shown on the drawings the chuck 24 is adapted to hold the drill shank in a position parallel with the base plate of the frame, and hence guide rods 18 must be inclined by the angle a to the base plate.

The angle B between the straight generatrices of the conical peripheral surfaces of the grinding wheel intersecting each other must be equal to the angle between two mutually adjacent flat cutting flanks belonging to adjacent cutting edges. On drills with four cutting edges the angle B amounts to approximately 132 and on drills with three cutting edges to approximately 147.

The grinding wheel 10 abuts linearily towards the two cutting flanks along a straight line located in a radial plane. The linear abutment between the grinding wheel and the cutting edge flanks of the drill causes the torque on the grinding wheel to be at a minimum, whereby the grinding wheelmotor 12 can be made small and light.

The grinding wheel 10 is enclosed in a protective hood 30, which at its lower portion is formed to a trough, from which grinding powder and cooling liquid is removed through the pipe 31. The grinding wheel is caused to rotate in the direction of the arrow 32, which means that the wheel in the grinding zone has a movement directed from the hard metal cutting edges of the tool towards its body or shank, which is made of steel Thus the movement of the grinding wheel in this zone has a component which is directed inwardly away from the cutting edge of the tool.

I claim:

1. A machine for sharpening of impact rock drills having a number of radially directed chisel cutting edges distributed around the axis of a drill crown, comprising:

A. a motor-driven grinding wheel having a peripheral surface defined by two intersecting frusto-conical sections;

B. a chuck having an axis located in the plane of the maximum perimeter of the grinding wheel for securely holding the drill crown and a drill shank during the sharpening;

C. a shaft mounting said grinding wheel with said shaft being rotatable but otherwise fixed during the sharpening;

D. means for guiding said chuck on one hand for a reciprocating grinding movement in a first direction parallel with an intersection line in said plane of the grinding wheel between planes through adjacent cutting flanks of the tool, and on the other hand for a feeding movement in a second direction perpendicular to said direction and also lying in said plane of the grinding wheel;

B. said guide means for said chuck including:

i. a base plate;

ii. a guide for the feeding movement of the chuck in said first direction being inclined at an acute angle towards said base plate, such that the axis of the chuck and hence the axis of a drill shank secured in the chuck are parallel with the base plate.

2. A machine for sharpening of impact rock drills having a number of radially directed chisel cutting edges distributed around the axis of a drill crown, comprising:

A. a motor-driven grinding wheel having a peripheral surface defined by two intersecting frusto-conical sections;

B. a chuck having an axis located in the plane of the maximum perimeter of the grinding wheel for securely holding the drill crown and a drill shank during the sharpening;

C. a shaft mounting said grinding wheel with said shaft being rotatable but otherwise fixed during the sharpening;

D. means for guiding said chuck on one hand for a reciprocating grinding movement in a first direction parallel with an intersection line in said plane of the grinding wheel between planes through adjacent cutting flanks of the tool, and on the other hand for a feeding movement in a second direction perpendicular to said direction and also lying in said plane of the grinding wheel;

E. said guide means for said chuck including:

i. a base plate;

ii. two parallel fixed guide rods inclined towards said base plate;

iii. two guide sleeves slidable respectively on said two fixed guide rods;

iv. two movable guide rods respectively carried by said two guide sleeves and perpendicular to the plane through said fixed guide rods; and

v. two further guide sleeves slidable along said movable guide rods and joined together as a unit and supporting said chuck.

3. A sharpening machine as claimed in claim 1, including a rotatably mounted feed screw having a hand wheel for causing feeding movement in said first direction, and a scale ring rotatably supported and adjustable to a desirable angular position, and a scale line on said hand wheel cooperating with said scale ring.

4. A sharpening machine as claimed in claim 1 for the sharpening of drills with three cutting edges, said chuck having jaws shaped for fixedly securing a hexagonal drill steel in correct grinding position.

Claims (4)

1. A machine for sharpening of impact rock drills having a number of radially directed chisel cutting edges distributed around the axis of a drill crown, comprising: A. a motor-driven grinding wheel having a peripheral surface defined by two intersecting frusto-conical sections; B. a chuck having an axis located in the plane of the maximum perimeter of the grinding wheel for securely holding the drill crown and a drill shank during the sharpening; C. a shaft mounting said grinding wheel with said shaft being rotatable but otherwise fixed during the sharpening; D. means for guiding said chuck on one hand for a reciprocating grinding movement in a first direction parallel with an intersection line in said plane of the grinding wheel between planes through adjacent cutting flanks of the tool, and on the other hand for a feeding movement in a second direction perpendicular to said direction and also lying in said plane of the grinding wheel; E. said guide means for said chuck including: i. a base plate; ii. a guide for the feeding movement of the chuck in said first direction being inclined at an acute angle towards said base plate, such that the axis of the chuck and hence the axis of a drill shank secured in the chuck are parallel with the base plate.

2. A machine for sharpening of impact rock drills having a number of radially directed chisel cutting edges distributed around the axis of a drill crown, comprising: A. a motor-driven grinding wheel having a peripheral surface defined by two intersecting frusto-conical sections; B. a chuck having an axis located in the plane of the maximum perimeter of the grinding wheel for securely holding the drill crown and a drill shank during the sharpening; C. a shaft mounting said grinding wheel with said shaft being rotatable but otherwise fixed during the sharpening; D. means for guiding said chuck on one hand for a reciprocating grinding movement in a first direction parallel with an intersection line in said plane of the grinding wheel between planes through adjacent cutting flanks of the tool, and on the other hand for a feeding movement in a second direction perpendicular to said direction and also lying in said plane of the grinding wheel; E. said guide means for said chuck including: i. a base plate; ii. two parallel fixed guide rods inclined towards said base plate; iii. two guide sleeves slidable respectively on said two fixed guide rods; iv. two movable guide rods respectively carried by said two guide sleeves and perpendicular to the plane through said fixed guide rods; and v. two further guide sleeves slidable along said movable guide rods and joined together as a unit and supporting said chuck.

3. A sharpening machine as claimed in claim 1, including a rotatably mounted feed screw having a hand wheel for causing feeding movement in said first direction, and a scale ring rotatably supported and adjustable to a desirable angular position, and a scale line on said hand wheel cooperating with said scale ring.

4. A sharpening machine as claimed in claim 1 for the sharpening of drills with three cutting edges, said chuck having jaws shaped for fixedly securing a hexagonal drill steel in correct grinding position.

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