US2275483A - Grinding apparatus - Google Patents

Description

. March l0, 1942. I R, B, PARKER 2,275,483

' @BINDING- APPARATUS Filed Jan. 15, 195'/ 4v sheets-sheet 1 A IY i g i i l Ml March 1o, 1942.' R, B PARKER 1 2,275,483

GRINDING'APPARATUS 120er/gaaf l mig/ Pawel? y Mal'Ch lo, 1942. R B PARKER GRINDING APPARATUS 4 Filed Jan. 15, 1937 4 sheets-sheet z Mmmm@ March 1o, 1942@ Mh l 53" l IE nth/3 Y v mmm R. B. PARKER @BINDING APPARATUS Filed Jan. l5, 1937y 4 sheets-sheet 4 Patented Mar. l0, 1942 GRINDING APPARATUS Robert B. Parker, Claremont, N. H., assigner to Sullivan Machinery Company,

Massachusetts a corporation of Application January 15, 1937, `Serial No. 120,768

Claims.

This invention relates to grinding apparatus, and more particularly, but not exclusively, has reference to an improved grinding apparatus for forming or sharpening the cutting portion of a vdetachable rock drill bit.

I'n rock drill bits of the detachable type the bits are usually discarded after one or two sharpenings. and therefore it is extremely desirable to provide a bit which is simple in design and which can be formed or sharpened with a minimum number of sharpening operations and with a minimum amount of handling. Such drill bits are usually sharpened on conventional grinding wheels simply by passing thebit manually across the grinding surface of the grinding wheel, the bit being manually supported and guided with respect to the wheel. It has been found by such manual sharpening operations that the cutting portions of the bit vary considerably, and frequently the bits were insuinciently ground, or were ground too much. resulting in a great decrease in efficiency and greatly increased cost oi drilling.

It is an object of this invention to provide an improved drill bit grinder, whereby all the objections of hand grinding are obviated, while at` the same time cost of forming or sharpening the bits is substantially reduced. Another object is to provide an improved bit grinder having an improved holder for the bit, whereby the bit may be accurately positioned with respect to the grinding wheel prior to the grinding operation, so that the cutting portions of the bit may be accurately and uniformly ground, thereby resulting in decreased bit cost and increased drilling'efliciency. Another object is to provide an 4 improved ,bit holder having improved means for positioning the bitl in either of two predetermined `grinding positions with respect to the grinding wheel. A further object is to provide an improved bit holder having improved means for moving the bit in an arcuate path with respect to the grinding wheel while the bit is at the same time moved automatically back and forth rectilinearly within the holder so that a straight grinding motion is imparted to the bit to form the parallel cutting portions of the bit. A still further object is to provide a vertically swingable holder pivotally mounted on a slide block on an axis parallel to the axis of the grinding wheel and movable bodily by the sliding block in a straight path toward and fromy the grinding wheel, the holder having a longitudinal bore in which is rotatably and reciprocably mounted a barrel for supporting the bit, the barrel rotatable into either of` two predetermined bit grinding positions with respect to the holder. A still further object is to provide a novel cam mechanism for reciprocating the barrel within the holder as the latter is swung about its pivot during the grinding operation. Yet another object is to provideY a novel device for positively and accurately locatingv the bit relative to the barrei of the holder. These and other objects and advantages of the invention will, however, hereinafter. more fully appear. y K

In the accompanying drawings there are shown for purposes of illustration one form and a modification which the invention may assume in practice.`

In these drawings Fig. l is a side elevational view of a grinding apparatus in which the illustrative form of the improved bit holder and bit locating device are embodied. l K i Fig. 2 is an enlarged rear end elevational'view of the grinding apparatus shown in Fig. 1, a portion of the frame being broken away to show details of construction.

' Fig. 3 is a fragmentary side elevational view of the grinding apparatus shown in Fig. 1 showing the different positions ofthe tool holder, a portion of the frame being shown in section to illustrate the tool holder support.

4 is a fragmentary view of the grinding wheel' showing a drill bit in operative grinding position with respect thereto.

Fig. 5 is an enlarged longitudinally extending vertical sectional view taken through the bit h'older shown in Fig. l.

Fig. 6 is a cross sectional view taken substantially on line 6 5v of Fig. 5.

Fig. 7 is a horizontal sectional View taken substantially on line 7--1 of Fig. 5.

Fig. 8 is a sectional view taken in the plane of Fig. 5, showing the blt holder barrel in partially released position with respect to `the holder oasing.

Fig. 9 is a cross sectional view taken on line 9 9 of Fig. 8, showing the barrel during turning thereof between its two predetermined bit grinding positions.

Fig. l0 is a fragmentary side elevational view, showing the cam mechanism for automatically moving the bit holder y:barrel rectilinearly with respect to the holder casing during swinging of the holder.

Fig. 11 is a detail sectional view showing the chuck for detachably securing the drill bit to the holder barrel,

cating device shown in Fig. 14.

Fig. 16 is a top plan view of Fig. 15.

Figs. 17 and 18 are detail side and end viewsl showing a modied form of operating means for the bit chuck.

In the illustrative embodiment of the invention disclosed, there is shown a grinding apparatus especially designed for grinding the cutting 4portions of a drill bit, such as a detachable rock drill bit of a character similar to that disclosed in the copending application to Paul H. Nast. Ser. No, 117,175, filed Dec. 22, 1936, now matured into Patent No. 2,168,102, granted August 1, 1929.

It will be evident, however. thatthe improved grinding apparatus may be employed in general grinding work. The improved grinding apparatus comprises a base frame I having journal'ed thereon for rotation about a horizontal axis at 2 a grinding wheel 3, having any appropriate driving means. Supported on the base frame I is a slide block 4 mounted for rectilinear movement on horizontal guides 5, 5. in the form of guide rods received in parallel bores 6, 6 in the slide block a'nd extending at right angles with respect to a line parallel to the axis of rotation of the grinding wheel, in the manner disclosed.

The means for manually adjusting the slide block y along its guideways comprises an adjusting screw 1 arrangedvparallel with the guide rods and threadedly ilxed at 8 to a block 9 secured to the base frame. A rotatable nut I0 is rotatably secured to the slide block at II, and is threadedly engaged with wthe screw, the nut having a hand wheel I2 for rotating the same. .'I'his hand wheel is made hollow, so that as the nut moves along the screw inwardly from the position shown in Fig. 5, the outer portion of the screw enters the hollow portion of the hand wheel. Secured to the upper surface of the sliding block is a bracket I3 having upstanding side arms I4 in which is trunnioned on a horizontal axis at I5 a bit holder, generally designated I6, of an improved and novel design. 'I'he bit holder comprises an outer sleeve-like casing or cylindric shell I1 formed with a bore I8 and having lateral trunnions I9 pivotally supported as above described in the bracket side arms. The pivotal axis I5 of the bit holder is, in this instance arranged parallel to the grinding wheel axis, and preferably lies in a horizontal plane including the grindngwheel axis.

As shown in Fig. 5, the rotatable and reciprocablebarrel of the drill bit holder comprises a cylindrical sleeve 2i rotatably and slidably mounted in the bore I8 of the outer holder shell and arranged with itsh axis of rotation offset laterally from a vertical plane disposed midway bel tween the outer plane surfaces of the grinding wheel, as clearly shown in Fig. 2. The sleeve 2l has front and rear head members 22 and 23 secured, as-by screws. to the sleeve, and the front head 22 has a number of forwardly projecting prongs or jaws 24 (see also Figs, 11, 12 and 13) exteriorly serrated at 25 and formed with inner inclined surfaces 26 engageable with the exterior surface of a jaw expanding wedge 21. A pinv 28 rigidly fixed to the wedge and projecting .in a space between a pair of prongs or jaws prevents rotation of the wedge relative to the head. 'I'his wedge is internally threaded and constitutes a nut threadedly engaging ra screw 29 formed on an operating rod 30. This operating rod extends axially through the barrel and is journaled in a bore in the front head and in a sleeve 3| supported within the rear head. and the rod is threadedly secured at 32 withinthe hub of a hand wheel 33. The serrated prongs or Jaws of the chuck are receivable within a threadedsocket 24 oi.' the drill bit designated 35, and when the operating rod is rotated by the hand wheel the nut of the non-rotatable wedge effects inward movement of the wedge, thereby spreading the prongs or jaws of the chuck apart and causing the serrations on the prongs to grip the drill bit to hold securely the bit in grinding position on 1 rically disposed locating pins 31 selectively re' ceivable in a longitudinal locating slot 28 formed in a member 39 fixed by a screw to the outer casing of the holder. It will thus be seen that when the operator moves the holder barrel rearwardly within the bore of the outer casing from the position shown in Fig. 5 to that shown in Fig. 8, a pin is released from the slot 38, and the barrel may then be rotated through and moved axially inwardly within the holder shell bore vto bring the other pin in proper relation with respect to the slot. This arrangement is necessary, due to the particular formation of the cutting surfaces of the drill bit, so that the par- 'allel cutting portions of the bit may be brought into proper grinding relation with the grinding wheel. v

Cam mechanism is provided for moving the bit holder barrel rectilinearly back and forth within the bore of the outer casing as the latter is swung about its pivot comprising a member 40 attached to the bracket I3, and having a cam surface 4I with which a roller 42 journaled on the rear head 23 is engageable. 'Ihe surface of the cam is preferably struck on a radius from a point lying in a horizontal plane including the rotation axis oi' the wheel and the pivotal axis of the holder. Secured to the rear head 23 of the barrel is a handle 43 by means of which the holder may be swung vertically about its pivot.

. Now referring to the particular structure of the drill bit and the grinding wh'eel shape, it will be noted that formed on the cutting face of the bit are wedge-shaped converging plane surfaces 45, 45 terminating along aimed diametrically arranged cutting edges 46, 46, and arranged diametrically at the opposite sides of the alined cutting edges near the outer periphery of the bit are chopping edges 41, 41 having inclined plane surfaces 48. The surfaces of the cutting edges and the surfaces 48, in this instance, lie in the sides of dihedral angles, and the surfaces converge along lin parallel with the cutting edges. The specific bit structure does not per se enter into this invention and is clearly disclosed in the Nast application above mentioned, therefore a more detailed description thereof is considered lunnecessary. As clearly shown in Fig. 4, the

grinding wheel is shaped with relatively inclined grinding surfaces 49, 49, one of less angle than the other and shaped to conform to the shape of theplane cutting surfaces on each side of the bit.

From the foregoing, it will be evident that the cutting surfaces on the bit have their elements extend in parallelism across the bit face, and therefore it is necessary to move the blt in and out rectilinearly relative to the holder as the latter is swung vertically about its pivot, so that these plane bit surfaces are appropriately ground.

Improved means is provided for definitely and accurately locating the drill bit 35 relative to the holder barrel so that when the barrel is inserted inproper position within the holder. as is dennitely determined by the locating pin on the barrel engaging the slot on the holder, this improved locating means positively locates the bit on the barrel so that the cutting surfaces of the bit are maintained in parallelism With the barrel locating pins. This improved locating means comprises, as shown in Figs. 14, 15 and i6, a frame 50 having a circular base iii adapted to rest on a horizontal supporting surface and formed with an upstanding portion $2 to which is bolted a vertical arm 5t.' Formed integral with the base at` the opposite side'thereor from the upstanding portion 52 is a lug 5ft, and supported within this lug and the upstanding `portion are parallel horizontal abutment pns d5, These pins are spaced equally from and in parallelism with a diametric line passing through lthe center ofthe circular frame base, as shown in Fig. 16. Formed integral with the upstanding frame portion is an annulus 55 having a bore i'l arranged with its axis alined with the base center. rEhe upper portion of the vertical arm is vertically slotted at 5E. When it is desired to locate the drill bit relative to the barrel, the drill bit is iirst placed in position on the frame with the side surfaces t5, t5 of the cutting edges lili projecting between and engaglng the parallel abutment pins :in the manner shown in Fig. le, and the barrel of the bit holder is then inserted down into the bore in the annulus 5S ci the frame with the pin 3l on the barrel in registry with the vertical slot 58. The operator then operates the chucl: to connect the bit to the barrel. It will thus be seen that by means of the improved locating means, the plane surfaces of the cutting portion ofthe bit are always located in parallelism with the abutment pins 55, :EE and the pins Si' on the barrel, so that when the barrel is placed in the holder, the pin on the barrel definitely locates the barrel and bit relative to the holder and grinding wheel.

In Figs. i7 and id a modiiied form of operating' meansior the bit chuck is disclosed. n lieu of the hand wheel iii and the nut and scr w operating means for the chuck jaw expanding wedge, the operating rod lill is non-threaded and is rigidly xed to the wedge 2l' in any suitable manner. Secured to the outer end of the operating rod @u is a trunnion block 6l having pivotally mounted thereon at a cam member 63 engaging the end surfaces of the rear barrel head and provided with an operating lever tl. When the cam lever dfi is in the position shown in Fig.

\ 18, the operating rod du is moved axially outwardly to move the wedge into its jaw expanding position. When the cam operating lever is moved into a position in alinement with the operating rod, the cam operating wedge is, of course, released. v

The mode of operation of the illustrative form of the improved grinding apparatus will be clearly apparent from the description given. When it is desired to attach a drill bit to the holder barrel, the barrel is removed from the holder casing and placed in the locating device in the manner above described, so vthat the proper position of the bit relative to the'holder is attained. The

proper angle of the bit is maintained with re.

spect to the grinding wheel 3. The operator then rotates the hand wheel i 2 to adjust the slide block toward or from the grinding wheel, so that the drill blt is properly positioned with respect to the grinding wheel. The operator then grasps the handle 43 of the holder and swings the holder vertically about its pivot, thereby swinging the bit across the grinding surfaces 49, 49 of the grinding wheel, the bit, as it swings across the grinding wheel surfaces, moving automatically in and out rectilinearly by means of the cam mechanism 4l, 42 so 'that the proper re- `lation of the bit surfaces with respect to the grinding wheel is automatically maintained. When the surfaces on the bit at one side of the bit are properly ground, the barrel is moved rearwardly to withdraw the active locating pin 3l from the locating slot 38 and the barrel is then turned through 18 to bring the other locating pin 31 into registry with the locating slot and the barrel thereafter shoved inwardly within the holder, and the grinding operation above described is then repeated to complete the grinding of the bit face.

As a result of this invention, it will be noted 'that an improved grinding apparatus is provided for a detachable rock drill bit whereby the cutting surfaces of the bit are accurately and uniformly ground. It will further be noted that an improved bit holder is provided which is of an extremely simple design and may be applied to a standard form of grinding apparatus. It will further be noted that by arranging the holder in the manner disclosed, the bit is securely held in position during the grinding operation and may be quickly adjusted into either of two predetermined grinding positions with respect to the holder simply by rotating the barrel within the holder casing. It will further be evident that by the provision of the cam mechanism, it is possible to effect grinding of parallel cutting portions of the bit by simple swinging movements of the holder, the cam mechanism automatically effecting in and out rectilinear movements of the bit as the holder is swung, thereby always maintaining the bit in proper grinding relation with respect to the grinding wheel. It will still further be evident by the provision of the improved bit locating device, the bit is definitely land accurately positioned with respect to the grinding wheel. Further, by pivotally mounting the bit holder in the manner disclosed, and moving the barrel rectilinearly in and out as the holder is swung about its pivotal mounting, it is possible to grind the-parallel planesuriaces of the bit face while the weight of the holder at the opposite sides of the pivotal axis thereof, is substantially counterbalanced, thereby greatly facilitating manipulation of the holder, and as a result speeding up the grinding process.` These and other uses andadvantages of the improved grinding apparatus will be clearly apparent to those skilled in the art.

While there are in this application specifically described one form and a modication thereof which the invention may assume in practice, it will be understood that this form and modification of the same are shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims. i

What I claim as new and desire to secure by Letters Patent is:

1. In a drill bit grinding apparatus, a frame, a

' grinding wheel journaled on said frame for rotation on a horizontal axis, a guide on said frame extending at right angles to a line parallel to f the grinding wheel axis, a slide block guided on said guide formovement toward and from the grinding wheel, a holder pivotally mounted on said slide block for swinging movement in a vertical direction about an axis parallel to the grinding wheel axis, said holder pivot axis lying extending at right angles to a line parallel to the grinding wheel axis, a slide block guided on ment, as said holder is swung, rectilinearly in an endwise direction b'ack and forth relative to said wheel and toward and from the latter, along lines lying in a plane perpendicular to the axis of rotation of said wheel, and means for always automatically moving said barrel during bit grinding rectilinearly relative to said holder during swinging of the latter. 4 6. In a drill bit grinding apparatus, the combination comprising a grinding wheel having a peripheral grinding surface, and means adapted to support a drill bit to be ground and for moving said bit with .respect to said wheel during grinding. and embodying means for maintaining the -bit axis in a plane perpendicular to the axis of rotation of said wheel during such bit movement, to cause all `the points in the surface of said bit to 'move at the instant of their formation by said wheel in lines tangential to the wheel, said bit supporting and moving means comprising a swingable holder, a barrel adapted to support the bit and mounted on said holder for movement, as said holder is swung, rectilinearly back and forth in an endwise direction relative to said wheel and toward and from the latter, along lines lying in a'plane perpendicular to the axis of rotation of said wheel, means for said guide for movement toward and from the grinding wheel, a holder pivotally mounted on said slide block for swinging movement in a vertical direction about an axis parallel to the grinding wheel axis, said holder pivot axis lying in a horizontal plane including the axis of rotation of said grinding wheel, a barrel for vsupport-,- ing a bit to be ground and mounted on said holder for movement rectilinearly back and forth relative to the-holder as the latter is swung, and means for moving said barrel rectilinearly relative to said holder during swinging of the .latter including cam mechanism comprising a cam elementon said holder and a cooperating element on said barrel.

3. In a drill bit locating means, a frame having parallel abutments and a locating slot, a bit holder adapted to carry a bit having spaced cutting surfaces, and means for locating said bit relative to saidv holder and said holder relative to said frame with said bit surfaces engaging said` abutments including a pin carried by said holder and receivable in said frame slot for locating said pin in parallelism with said parallel abutments.

4. In a drillbit locating means, a frame having parallel abutment pins, a bit holder adapted to carry a bit having relatively inclined cutting surfaces, and means for locating said bit relative to said holder with said bit surfaces engaging ysaid abutment pins including a pin carried by said holder and a slot on said frame for receiving said last mentioned pin for positioning the latter in parallelism with said abutment pins.

5. In a drill bit grinding apparatus, the combination comprising a grinding wheel having a peripheral grinding surface, and means adapted to support a drill bit to beground and forI moving the drin bit with respect to the grinding wheel periphery during grinding, and embodying means for maintaining the bit axis in a plane perpendicular to the axis of rotation of said always automatically moving said barrel during bit grinding rectilinearly relative to said holder during swinging of the latter. and means whereby said barrel may be rotated into either of two predetermined blt supporting positions with respect to said holder.

'7. In a drill bit grinding apparatus, the combination comprising a grinding wheel having a peripheral grinding surface, and means adapted to support a drill bit to be ground and for moving'said bit with respect to said wheel during grinding, and embodying means for maintaining the bit axis in a plane perpendicular te the axis of rotation of said wheel during such bit movement, to cause all the points in the surface of the bit to move at the instant of their formation by said wheel in lines tangential to said wheel, said bit supporting and moving means comprising a swingable holder, a barrel adapted to support the drill bit and mounted on said lholder for movement, as said holder is swung,

4bination comprising a grindingwheel having a peripheral grinding surface, and means adapted to support a drill bit to be ground and for moving said bit with respect to said `wheel during grinding, and embodyingmeans for maintaining the bit axis in a plane perpendicular to the axis of rotation of said wheel during such bit movement, to cause al1 the points in the surface of the bit to move at the instant of their formation by said Wheel in lines tangential to said wheel, said bit supporting and moving means comprising a swingable holder mounted for pivotal movement about an axis parallel to the axis of rotation of said wheel, a barrel adapted to support the drill blt and mounted on said holder for movement, as said holder is swung, rectilinearly back and forth in an endwisedirection relative to said wheel and toward and from the latter, along lines lying in a planef 1o. In a drill bit grinding apparatus, the combination comprising a grinding wheel having `a s peripheral grinding surface. and means adapted said barrel rectilinearly relative to said holder during swinging o! the latter.

. 9. In a bit grinding apparatus, the combination comprising a rotatable grinding wheelhaving a peripheral grinding surface. and means' adapted to support a bit and for moving the bit relative to said grinding wheel during grinding, and embodying means for maintaining thc bit axis in a plane perpendicular to the axis of rotation of said wheel, said bit supporting and moving means including means for supporting the bit for arcuate movement relative to said wheel surface, and also including means i'or simultaneously moving the bit in a direction normal with respect to such arcuate movement to move the bit relative to said wheel periphery in such al path that each point in the bit which contacts with a given circle in the wheel periphery during bit grinding lies in a straight line to support a drill bit to be ground and for movling the drill bit relative to said wheel during grinding to cause all the points in the surface oi' the bit to traverse the peripheral grinding wheel surface along lines tangential to said wleel,

said bit supporting and moving means including a holder swingable about an axis parallel with the axis of rotation of said grinding wheel. a barrel adapted to support the drill bit to be ground and guided on said holder for rectilinear movement back and forth in an endwise .direction relative to said holder and toward and from the grinding wheel along lines lying in a plane perpendicular to the axis of rotation of said wheel, and means for always automatically moving said barrel during bit grinding rectilinearly relative to said holder during swinging of the latter about its pivotal axis to cause all the points in the surface oi' the bit to traverse said peripheral grinding wheel surface along l lines tangential to 'thewheeL perpendicular to a linel parallel to the bit axis.

ROBERT B. PARKER..

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