US3900970A

US3900970A - Cutter bit grinder

Info

Publication number: US3900970A
Application number: US398064A
Authority: US
Inventors: Phillip A Sollami
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-09-17
Filing date: 1973-09-17
Publication date: 1975-08-26
Anticipated expiration: 1992-08-26

Abstract

Apparatus for grinding the steel portion of a steel and carbide cutter bit includes a bit holder, a support for moving said bit holder between a loading position away from a grinding wheel and a grinding position wherein the bit is pressed against the wheel.

Description

United States Patent Sollami Aug. 26, 1975 [5 CUTTER BIT GRINDER 2,246,023 6/1941 Spurling 51/218 R [76] Inventor: Phillip A. Sollami, 438 Sherman St., 3 311 32 33:5, 5 ,1

Downers Grove, 60515 2,988,858 6/1961 Bass 51/1659 x Pettee X Appl. No.: 398,064

U.S.Cl ..51/98 BS;5l/2l5 UE',51/218R Int. Cl B24b 3/36 Field of Search 51/98 R, 98 BS, 98.5, 125, 51/1255, 215 CP, 215 UE, 218 R, 91 R, 91 BS, 224, 230, 94, 165.9, 96, 234; 269/94 References Cited UNITED STATES PATENTS 6/1939 Bower 51/234 Primary Examiner-Al Lawrence Smith Assistant ExaminerNicholas P. Godici Attorney, Agent, or Firm-Edmond T. Patnaude 5 7] ABSTRACT 7 Claims, 4 Drawing Figures CUTTER BIT GRINDER The present invention relates in general to grinding apparatus of the type employing a rotating grinding wheel and a work piece holder, and it relates more particularly to semiautomatic apparatus for grinding the steel portion of a carbide cutter bit used in the coal mining industry.

BACKGROUND OF THE INVENTION The cutter bit most commonly used in the coal mining industry consists of a carbide cutting tip held in a steel holder. Frequent sharpening of the bits is necessary, and the sharpening operation entails the grinding of both the carbide tip and the adjacent portion of the steel holder. The grinding operation is generally done by hand which is both tedious and hazardous and which results in inconsistently sharpened cutter bits. Moreover, because of the different characteristics of the carbide and the steel, the use of a single grinding wheel for removing the carbide and the steel is extremely inefficient and results in short wheel life. The use of composite wheels having adjacent portions for respectively grinding the steel and the carbide has increased wheel life but the quality of the sharpened bits has not been improved.

OBJECTS OF THE INVENTION In order to enable the sharpening of cutter bits in a safe and economical manner while producing sharpened bits of consistently high quality and shape, a principal object of the present invention is to provide semiautomatic grinding apparatus which moves a manually fed bit holder between a loading position remote from the grinding wheel and an adjustable preset grinding position where it is urged under fluid pressure for a predetermined period of time against the edge of a grinding wheel to grind the steel portion only of the bit. The carbide tip is ground in a separate operation.

Another object of the present invention is to provide a novel cutter bit holding fixture which enables the rapid, safe and facile loading of the bits by a relatively unskilled operator.

A further object of this invention is to provide semiautomatic cutting bit sharpening apparatus which can be manufactured at a sufficiently low price to be competitively marketed.

SUMMARY OF THE INVENTION The above and further objects may be realized in accordance with the present invention by providing a cutter bit holding fixture adjustably mounted on an upright member which is pivotably mounted on a base plate re ciprocably mounted for rectilinear movement in a direction parallel to the plane of the associate grinding wheel. The upright member pivots about an axis perpendicular to the plane of the wheel thereby to swing the bit holder to the side of the wheel to facilitate loading of a bit therein. The upright is pivoted by means of a fluid operated piston and cylinder, and the base plate is reciprocated by a fluid operated piston and cylinder which also pushes the bit against the grinding wheel with a predetermined force. Control means coordinates the actuation of the two cylinders and of a clamping mechanism in the bit holder to urge the bit against the grinding wheel for a predetermined time whereby successive bits are ground to substantially the same configuration.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantages and a better understanding of the invention may be had from the following detailed description taken in connection with the accompanying drawings, wherein:

FIG. 1 is an elevational view of a cutter bit grinding apparatus embodying the present invention;

FIG. 2 is a partially sectioned view of the apparatus of FIG. 1 taken along the line 22 thereof;

FIG. 3 is a plan view of the holding fixture portion of the machine of FIG. 1 taken from the line 33 thereof; and

FIG. 4. is a sectional view taken along the line 44 of FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS Referring now to the drawings and particularly to FIGS. 1 and 2 thereof, a machine 10 for grinding the steel portions of cutter bits comprises a base plate 11 to which a pair of

brackets

12 and 13 are fixedly secured as by welding. The

brackets

12 and 13 include

flange portions

12a and 13a lying at an angle of 45 and to which a pair of channel shaped

guide rails

14 and 15 are secured. A support plate 16 is slidably connected to the

rails

14 and 15 by four roller bushings 17 threadedly mounted to the side edges of the plate 16 by studs 18. The studs 18 also lie at an angle of 45 whereby the

rails

14 and 15 prevent both vertical and lateral movement of the plate 16 relative to the base plate 11 while permitting horizontal movement thereof along an axis parallel to the plane of a grinding wheel 19. A pneumatic or hydraulic cylinder 22 is mounted between the

plates

11 and 16 by a pair of

clevices

23 and 24 for reciprocably moving the plate 16 in a horizontal direction in the

guide rails

14 and 15.

Mounted to the top of the plate 16 is a pair of

pillow blocks

25 and 26 in which a horizontal shaft 27 is journaled by suitable spherical bearings 30. An upright member or post 28 is fixedly mounted to the shaft 27 by a sleeve 29 welded to the post and press fitted onto the shaft 27. The post 18 may thus pivot in a vertical plane perpendicular to the axis of reciprocation of the plate 16. A pneumatic or hydraulic cylinder 32 is interconnected between the plate 16 and the post 28 for controlably pivoting the post 28 about the shaft 27. More particularly, the cylinder 32 is pivotably connected to a clevice bracket 33 welded to the plate 16 and the piston of the cylinder 32 is pivotably connected to a lug 34 fastened to the upright near the top thereof. The upright grinding position of the post 28 is adjustable by means of a stop bolt 35 threadly received in a lug 36 fixed to and extending from the post 28.

A mounting platform 38 is fixed to the top of the post 28 by a pair of

arms

39 and 40 and a cutter bit holding fixture 43 is adjustably supported on the plate 38 by a plurality of bolts 44 which extend through enlarged holes in a plate 45 and are threadedly received in correspondingly located tapped holes in the platform 38. As best shown in FIGS. 3 and 4, the plate 45 is part of the holding fixture 43, and a pair of guide strips 46 are adjustably mounted thereon by a plurality of bolts 47 which extend through elongated openings or slots 48 in the guide strips 46. The guides 46 and the intermediate surface of the plate 45 thus define a guide channel for receiving the shank of a cutter bit 50.

The shank portion of the cutter bit 50 is slidably received in the channel between the guide members 46, which channel is disposed at an angle of between and relative to the plane of the grinding wheel 19. By proper adjustment of the guide members 45 the carbide tip portion 51 of the bit is positioned immediately adjacent the edge 52 of the grinding wheel 19 so that the working surface 53 of the wheel 19 engages only the steel portion of the bit back of the carbide tip 51.

In order to clamp the bit 50 in the holding fixture, a lever arm 55 is pivotably mounted on a horizontal shaft 56 held between a pair of

brackets

57 and 58 bolted to the plate 45. A clamping pad 59 is connected to the forward end portion of the lever arm 55 and locked in place by a nut 62. A ball and socket connection (not shown) is provided between the stud 60 and the pad 59 to permit the flat bottom surface 63 of the pad to seat flat against the upper surface of the shank of the bit 50 lying on the plate 45-between the guide members 46. A fluid operated cylinder 66 is mounted to the rearward end portion of the lever arm 55, and a push pin 67 is threadedlyconnected to the piston thereof. When the cylinder 66 is actuated to project the piston, the pin 67 presses against the plate 45 to lift the rearward end of the lever arm 55 and press the pad 59 against the bit 50 to clamp it against the plate 45 in the guide channel. At the completion of the grinding operation the piston is retracted in the cylinder 66 and the weight of the cylinder causes the lever to pivot in a counterclockwise direction as viewed in FIG. 4 to lift the pad 59 and release the bit. A spring loaded air cylinder 70 is mounted to the plate 45 by a bracket 71 and includes a pin 72 connected to the piston for ejecting the ground bit from the holding fixture when the cylinder 70 is actuated with the pad 59 lifted off the bit.

OPERATION The

cylinders

22, 32, 66 and 70 are operated in a controlled sequence as described below by any suitable timing mechanism such, for example, as motor driven, switch actuating cams. At the end of a grinding cycle, the pistons in all of the cylinders are in the retracted positions whereby the plate 16 is in a fully rearward position and the post 28 is tilted downwardly to the right as shown in FIG. 1 whereby the front end of the holding fixture 43 is about four to six inches from the right hand face of the wheel 19.

The operator loads a bit into the fixture by sliding it between the guides 46 along the top surface of the plate 45 until a rearwardly facing shoulder 74 on the bit abutsthe foreward end of the left hand guide member 46. This position is best illustrated in FIG. 3. Since the plate 45 lies at an angle of about 75 to the horizontal at this time, the bit will remain in the inserted position resting on the plate 45 and the right hand guide member 46. The operator then simultaneously actuates two start switches, one with each hand, to initiate a grinding cycle.

Closing of the start switches energizes the timer motor which first actuates the cylinder 66 to force the clamping pad 59 against the cutter bit to lock it in place in the fixture. The

cylinders

22 and 32 are actuated at about the same time to move the cutter bit into the grinding position directly opposite the horizontal diameter of the grinding wheel. The rate of fluid flow to the

cylinders

22 and 32 is mutually related so that the post 28 reaches its fully upright grinding position with the end of the bolt 35abutting the plate 45 before the plate .16 has moved forewardly a sufficient amount to cause the bit to engage the wheel. Continued movement of the plate 16 under the force exerted thereon by the cylinder 22 then presses the steel portion of the cutter bit against the edge of the wheel as shown in FIG. 3. The bit 50 is thus pushed at a predetermined pressure as determined by the cylinder 22 against the wheel along an axis which intersects the rotational axis of the wheel at an angle of 90 to grind away a portion of the steel directly behind and adjacent to the carbide tip 51. After a predetermined grinding time as determined by the timer,the cylinder 22 is actuated to move the plate 16 rearwardly thereby to retract the ground bit away from the wheel 19. Shortly thereafter the cylinder 22 is actuated to swing the holding fixture downwardly to the right. The

cylinders

22 and 32 simultaneously retract the respective pistons until the fixture is in loading position. The cylinder 66 is then actuated to retract the piston whereby the lever arm pivots counterclockwise to lift the pad 59 from the bit. An impulse of air is then supplied to the cylinder to sharply drive the eject pin against the rear end of the cutter bit 50 to eject it from the fixture into a suitable container located below and to the right of the wheel 19. The grinding cycle is thus completed with the holding fixture stopped in the loading position and the clamping pad elevated to permit insertion of the next bit to be ground.

A complete grinding cycle from loading to ejection lasts approximately four seconds with the actual grinding time being 1.5 to 2 seconds. Using an aluminum oxide wheel having a diameter of twelve inches rotating at a speed of 1,725 rpm and a force of between 20 and 50 lbs on the bit, a grinding period of 1.5 to 2 seconds provides sufficient steel removal for a normal cutter bit. Where the carbide tips'have been sharpened many times so that the amount of steel to be removed is near a maximum, the higher grinding force is recommended. In this respect, in normal practice the operator will group the bits to be ground so that each group can be ground without adjustment of the pressure to the cylinder 22.

While the present invention has been described in connection with particular embodiments thereof, it will be understood that those skilled in the art may make many changes and modifications without departing from the true spirit and scope thereof. Accordingly, the appended claims are intended to cover all such changes and modifications as fall within the true spirit and scope of the present invention.

Whatl claim is:

1. semiautomatic apparatus for feeding a combination steel and carbide cutter bit against a grinding wheel for grinding the steel portion of the bit, comprising a base member disposed in fixed relationship to a grinding wheel,

guide rail means mounted on said base member,

a support member slidably supported by said guide rail means for reciprocable movement toward and away from said grinding wheel,

an upright member mounted to said support member for pivotablemovement in a plane perpendicular to the direction of movement of said support member,

a bit holding fixture mounted on said upright member,

said holding fixture including a clamp for locking said bit in said fixture with the steel portion thereof opposite said grinding wheel,

fluid operated means for moving said support member along said rail means, and

drive means for pivotably moving said upright member in said plane,

whereby energizing said fluid operated means and said drive means moves a bit held in said fixture to a position opposite the edge of said grinding wheel and then urges said bit against the edge of said grinding wheel at a predetermined force.

2. Apparatus as set forth in claim 1 wherein said fixture comprises a guide channel for receiving the shank of the bit to be ground, and said clamp includes first means for selectively clamping said bit in said channel, and

selectively operated means for ejecting said bit from said channel.

3. Apparatus as set forth in claim 2 comprising means for adjusting the position of said fixture on said upright member.

4. Apparatus as set forth in claim 2 wherein said first means comprises a support plate,

an arm pivotably supported on said support plate,

a bit engageable clamping pad carried near one end of said arm for clamping a bit against said plate, and

a fluid operated means connected near the other end of said arm for pivoting said arm to urge said clamping pad against said bit to lock it in place in said fixture.

5. Apparatus as set forth in claim 4 wherein said slectively operated means comprises a pneumatic cylinder and piston assembly.

6. In combination,

a grinding wheel mounted for rotation about a first horizontal axis,

said wheel having a generally cylindrical grinding edge and circular sides,

a fixture for holding a work piece to be ground,

support means for supporting said fixture in a grinding position opposite said grinding edge of said wheel and in a loading position below said grinding position and off to one side of said wheel,

trunnion means mounting said support means for arcuate movement about a second axis disposed below said wheel and extending horizontally,

power operated means for angularly moving said support means about said second axis to move said fixture between said grinding and loading positions, and

means for moving said support and said trunnion means in a horizontal linear direction toward and away from said wheel.

7. The combination set forth in claim 6 wherein said fixture comprises a cutter bit receiving guide channel for holding a cutter bit at an angle of between 10 and 20 relative to the plane of said grinding wheel when said fixture is in said grinding position.

Claims

1. Semiautomatic apparatus for feeding a combination steel and carbide cutter bit against a grinding wheel for grinding the steel portion of the bit, comprising a base member disposed in fixed relationship to a grinding wheel, guide rail means mounted on said base member, a support member slidably supported by said guide rail means for reciprocable movement toward and away from said grinding wheel, an upright member mounted to said support member for pivotable movement in a plane perpendicular to the direction of movement of said support member, a bit holding fixture mounted on said upright member, said holding fixture including a clamp for locking said bit in said fixture with the steel portion thereof opposite said grinding wheel, fluid operated means for moving said support member along said rail means, and drive means for pivotably moving said upright member in said plane, whereby energizing said fluid operated means and said drive means moves a bit held in said fixture to a position opposite the edge of said grinding wheel and then urges said bit against the edge of said grinding wheel at a predetermined force.

2. Apparatus as set forth in claim 1 wherein said fixture comprises a guide channel for receiving the shank of the bit to be ground, and said clamp includes first means for selectively clamping said bit in said channel, and selectively operated means for ejecting said bit from said channel.

4. Apparatus as set forth in claim 2 wherein said first means comprises a support plate, an arm pivotably supported on said support plate, a bit engageable clamping pad carried near one end of said arm for clamping a bit against said plate, and a fluid operated means connected near the other end of said arm for pivoting said arm to urge said clamping pad against said bit to lock it in place in said fixture.

6. In combination, a grinding wheel mounted for rotation about a first horizontal axis, said wheel having a generally cylindrical grindinG edge and circular sides, a fixture for holding a work piece to be ground, support means for supporting said fixture in a grinding position opposite said grinding edge of said wheel and in a loading position below said grinding position and off to one side of said wheel, trunnion means mounting said support means for arcuate movement about a second axis disposed below said wheel and extending horizontally, power operated means for angularly moving said support means about said second axis to move said fixture between said grinding and loading positions, and means for moving said support and said trunnion means in a horizontal linear direction toward and away from said wheel.

7. The combination set forth in claim 6 wherein said fixture comprises a cutter bit receiving guide channel for holding a cutter bit at an angle of between 10* and 20* relative to the plane of said grinding wheel when said fixture is in said grinding position.