CA1168033A - Method and apparatus for grinding button bits - Google Patents
Method and apparatus for grinding button bitsInfo
- Publication number
- CA1168033A CA1168033A CA000359748A CA359748A CA1168033A CA 1168033 A CA1168033 A CA 1168033A CA 000359748 A CA000359748 A CA 000359748A CA 359748 A CA359748 A CA 359748A CA 1168033 A CA1168033 A CA 1168033A
- Authority
- CA
- Canada
- Prior art keywords
- grinding
- disc
- button
- plate member
- button bit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B3/00—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools
- B24B3/24—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of drills
- B24B3/33—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of drills of drills for stone
Abstract
ABSTRACT
This invention relates to a method and an apparatus for restoring the shape of button bits by grinding every button.
At known technique the buttons are dressed by a hand-held grinder, which normally also is used for removing steel material of the bit about the buttons. It was, however, found impossible by this method to satisfy satisfactorily the prevailing demand for regrinding button bits. For solving this problem, according to the invention a method is proposed which is characterized in that the button in the bit to be ground is caused to rotate substantially about its own long-itudinal axis, and that thereafter grinding is carried out in two subsequent steps for removing material about the button by a first grinding wheel and for forming the button by a second grinding wheel.
This invention relates to a method and an apparatus for restoring the shape of button bits by grinding every button.
At known technique the buttons are dressed by a hand-held grinder, which normally also is used for removing steel material of the bit about the buttons. It was, however, found impossible by this method to satisfy satisfactorily the prevailing demand for regrinding button bits. For solving this problem, according to the invention a method is proposed which is characterized in that the button in the bit to be ground is caused to rotate substantially about its own long-itudinal axis, and that thereafter grinding is carried out in two subsequent steps for removing material about the button by a first grinding wheel and for forming the button by a second grinding wheel.
Description
' This invention relates to a method of grinding button bits and to an apparatus for carrying out the method.
When button bits w~re being introduced about ten years ago, the general understanding was that this type of bits had not to be reground, but could be used -to complete wear of -the buttons, whereafter the bit could be discarded. This idea has now been abandoned entirely, because experience clearly has shown that a much better drill economy is achieved by grinding the buttons and restoring their original spheric shape wi-th uniform interspaces. Hereby the demand has arisen to be able to regrind button bits, which demand latterly has grown substantially due to the ever increasing extent of using button bits instead of bits of X- and cross-type.
It was found almost impossible, however, to satisfy this demand by regr~inding button bits with known technique, at which the buttons are manually dressed by a hand-held grinder.
The method is complicated and troublesome, and it yields fully sa-tisfactory results only in a few cases, because in most cases it is not only the buttons which have to be restored to original shape, but also the lower surface of the bit body must be re~-tored which often is exposed to impact stresses and non-uniform wear. This implies that almost always steel ~ ~ ~8033 ma-terial about the button must be removed before the buttons can be dressed to the intended shape. It was tried to remove the steel material about the buttons by milling and grinding.
Milling, however, has proved tedious and, besides, requires complex machines. It was, therefore, preferred to remove the material in question by grinding with the same hand-held grinder, which is used for dressing the buttons. Grinding with such a grinder shows disadvantages, too, for example poor cutting pace, which renders also grinding a tedious method, not the least because very often the grinding wheel has to be replaced by another one, and also because there is risk that cracks will develop in the cemented carbide button,due to the great difficulties in arranging satisfactory cooling for a hand-held grinder. A further disadvantage of manual grinding is that grinding dust, which always forms at grinding, can be sucked oEf only with difficulty. Moreover, it is very difficult with a hand-held grinder to bring about the correct shape of the button. Correct shape, however, is of great importance for the penetration rate and the lifè of the button bit.
The present invention, therefore, has the object to provide for the grinding and regrinding of button bits a mechanical method, which does not involve the aforesaid diasadvantages, but renders much more rapid grinding possible, and which is less complicated than the known art in this field, which method nevertheless imparts to the but-ton the desired spherical or, more correctly, semi-spherical shape. A further ob;ect of the 7 ~ 3 3 in~ention is to produce an apparatus for carrying out the method, which apparatus is (~esigned so that it can be handled without difficulty even by semi-skilled operators.
According to the present invention, then, there is provided a method of restoring the shape of worn button bits by grinding each one of the buttons, wherein the button in the bit to be ground is caused to rotate substantially about its own longitudinal axis, and that thereafter grinding is carried out in two subseque:nt steps for removing material about the button in the first step by a first grinding wheel, and for forming the button in the second step by a second grinding wheel.
According to a further aspect of the present invention, there is also providea an apparatus for restoring the shape of w~rn button bits by grin~ing each one of the buttons, the apparatus comprising a rotary table, on which the button bit can be fixed in ~ position in which the button to be ground has its longitudinal axis substantially aligned with the rotational axis of the rotary table, and two grinding wheels arranged each on a spindle in a common grinding head, the grinding head being movable and rotatable in order to move first the first grinding wheel and then the second grinding wheel to a grinding position for grinding the button bit in two subsequent steps.
' .
According to yet another aspect of the present invention, there is further provided an apparatus for grinding a worn button bit having a plurali1:y of buttons formed thereon, the apparatus comprising me~ms for rotating the button bit holding means for retaining the button bit on the rotating means in a position for grinding with the button to be ground having its longitudinal axis aligned with the rotational axis of the rota1ing means, and first and second spaced apart grinding means movably mounted proximal the button bit for actuation be-ween grinding and inoperative positions thereof, wherein the first first and second grinding means may be successively moved into the grinding positions thereof for grind:ing the button bit and successive ones of the plurality of buttons.
:' .
Embodiments o:E the present invention will now be described in greater detai:L with reference to the accompanying drawings, in which Fig. l is a perspecti~e view of an apparatus or machine according to the invention, Fig. 2 is a front view of the upper part of the machine, Fig. 3 is a section of a fixture seen obliquely from below, and Fig. 4 is a vertical section on an enlarged scale through .~.i.~
.~
. ' .
.: .
3b the grinding table of the machine.
The apparatus or machine, which is illustrated in the drawings only by way of exarlple, comprises a stand 1 in the form of a table with a suitable w~rking height and intended to be placed on a support. An edging 2 extends all about the table top 3 proper. On the upper surface of the table top a holding plate 4 is attached which carries removably a fixture 5, in which a butlon bit 7 with buttons 6 to be reground is unmovably chucked in a holder 10, which is provided with substantially V-shaped seat 9 and chucking screw 8, and which can be set in different angular positions and be locked by a locking screw 11 in every position set.
~.
-- 1 3 6~33 The holding plate 4 rests with its surface-ground lower surf-ace 12 (Fig. 4) on a driving disc 13, which is also surface ground and has a su~stantially smaller diameter than the holding plate 4, so that the latter can be moved radially in relation to the driving disc 13 within the area defined by a circum-ferential flange 14 on the lower side of the holding plate.
The driving disc 13 is connected to a vertical shaft 15, which is supported and guided in a bearing bushing or holder 18, which is attached to the lower surface of the table top by means of a support plate 17 fastened with screws in carrier beams 1~. Said bearing bushing or holder 18 extends above the table plane and is enclosed by a protective edging 19, which like the edglng 2 prevents cooling liquid and the like from running off the table top 3 other than through an outlet tnot shownj provided for this purpose.
The vertical shaft 15 connected to the driving disc 13 is driven by a motor 20, which is suspended in the stand 1 and can be an electric, pneumatic or hydraulic one, via a miter gear 21, which preferabiy shall permit speed control, a coupling 22 and a swivel coupling-23 with an inlet 26, which via a channel 24 in the swivel coupling 23 and in the shaft 15 communicates with the space between the holding plate 4 and -the driving disc 13, which is sealed against said plate by a sealing ring 25. The said inlet 26 is connected via a conduit 27 and a hand- or foot-oper-ated valve (not shown) to a generator producing overpressure and underpressure, by means of which generator (not shown) and valve ~ ~ 6~033 an overpressure or underpre~sure can be established in said space between the holding plate 4 and the driving disc 13.
The overpressure is intended to detach the holding plate 4 from the driving disc 13 and to form an air cushion therebetween, which substantially facilitates the moving of the holding plate 4 relative to the rotation centre 28 of the driving disc. The u:nderpressure, in the form of a vacuum, is intended to rigidly connect the holding plate 4 to the driving disc 13 and thereby to cause the holding plate 4 to rotate at the same speed as the driving disc 13.
The holding plate ~ being easily movable relative to the driving disc 13, the fi.xture 5 and the button bit 7 can be set rapidly in relation to the rotation centre 28 of the driving disc. In order to additionally facilitate accurate centering o the button 6 to be ground, the present machine is equipped with a centering device 29, which is supported so as to be positively adjustable in its longitudinal direction by an arm 30. Said arm is mounted without ].ateral play proper in an upright 31 attached unmovably to the stand table 1 and is foldable downward t~ a position which is determined by a stop member 32 provided in said upright 31. In this position the longitudinal axis of the centering device aligns with the rotation axis 28 of the driving disc, and its preferably concave curved lower surface 33 indicates the height position for the button to be ground, and which, thus, can be rapidly and simply adjusted to the machining position intended~
., ~ .
Z 1 6gO33 5a The present machine further comprises two grinding wheels 34, 35~ one 34 of which is .intended to remove material about the buttons ' 1 ~ 6~33 6, and the other one 35 is intended to impart to the buttons the shape desired and a profile suitable therefor. The grind-ing wheels 34~35 are arranged exchangeably each on a spindle 36, which are located in a common grinding head generally designated by 37 and are driven in common or each separately by an electric, pneumatic or hydraulic motor 38 through a belt transmission 39, shown schematically in Fig. 3, at speeds intended for the grinding wheels 34,35.
The grinding head 37 is attached non-rotary on a bushing 40, for example a ball bushing, which is mounted movably on an axle 43 rotatably mounted in bearing holders 41,42, but not rotatable relative to said axle 43. This implies that upon rotation of the axle 43 also the bushing 40 and the grinding head 37 connected thereto are rotated. Thereby also the grind-ing wheels 34,35 can be swung by a control lever 60 connected to the grinding head from the non-operative or starting position shown in Fig. 2 to the operative position shown in Fig. 1, in which posi-tion the button 6 to be ground is set by means of the centering device 29. Between the ends of the bushing and the axle 43 bellaw-like sleeves 44, for example of rubber or the like, are arranged to prevent dust and other impurities from penetrating in bewteen the bushing 40 and axle 43~
The bearing holders 41342 are supported by an angular support 45 attached on the stand table and can be arranged for parallel shifting of the axle 43, although this is not shown in the drawing. In the drawings, one bearing holder 42 is shown to be rotatably connected to its angular support 45, while the second holder 41 is shown movable by means of a set screw 46, which is provided with a wheel, in a dovetail guide groove 47 in the associated angular support 45. By means of the set screw 46, thus, it is possible to change the pOSitiQn of the grinding wheels in relation to the rotation axis of the driving disc.
Thereby the present machine can also be adapted to a certain extent to different button diameters.
Owing to the fac-t that the grinding head can be moved and swung, each of the two spaced grinding wheels 34,35 can be moved to and from the operative or grinding position. For rendering possible a rapid and accurate setting of the respect~
ive grinding wheel in this position, a guide pin 48 is provided which is connected to the stand table 1 and by a guide roller co-operates with a substantially U-shaped guide groove 50 in a guide plate 51 connected to the grinding head 37. The legs 52,53 of said guide groove which are located in spaced rela-tionship corresponding to the distance between the centres of the spindles 36 and have a width corresponding to the guide roller 49, thereby fix the respective grinding wheels 34 and 3S
in a vertical ~lane extending -through the grinding position and,thus,guide the grinding wheel fixed in this plane while it is moving to and from the bit and the button to be ground, l.e. to and from the grinding position.
Ths grinding head 37 preferably shall be balanced so that it more or less by itself tends to set itself in the non-operative or starting position shown in Fig. 2, in which position the guide pin 48 assumes a position substantially halfway between the legs 52,53 of the guide groove. Owing to the co-operation ~ ~ 6 ~ 3 .~.
between the guide groove and the guide pin, it is, thus, simple to move one or the other of the grinding wheels 34,35 from said starting position by the;control lever 60 to grinding position and there with the grinding wheel 34 to grind off material about the centered and rotating button 6 and thereafter with the grinding wheel 35 to grind or dress the button or-j more precisely, its button end to the desired semi-spherical shape. The grinding force required is supplied by means of the control lever 60.
In Fig. 2 the grinding head 37 is shown in its starting position for a grinding operation. When the button in the bit to be ground has been centered by means of the centering device 29, so that its axis substantially coincides with the rota-tion axis 28 of the driving disc, the said hand- or foot-operated valve is actuated to connect the holding plate 4 and the driving plate with one another by underpressure and thereby to cause the holding plate 4, t-he fixture 5 and the bi-t 7 chucked therein to rotate abou-t the axis of the centered button. There-after~ and after the centering device 29 has been Eolded up, the control lever 60 is moved downward and possibly slightly to the left in Fig. 2, whereby the guide pin 48 by co-operation with the guide groove 50 moves the grinding head 37 to the left until the guide pin 48 can enter between the legs 52 of the guide groove, whereafter the grinding head 37 is swung down by the co~trol lever 60 to effect contact of the grinding wheel 34 with the bit and to remove material about the centered button 6.
Upon the downward swing of -the grinding head 37, a switch or , ~ 1~8~33 g the like (not shown) can be actuated automatically in order to effect in known manner cooling of the grinding zone by a cooling liquid ejected by a suitable nozzle (not shown).
After the necessary amount of material has been removed about the button 6, the grinding head 37 is moved up from the bit 7.
During this movement the cooling preferably automatically is interrupted. The grinding head then is moved to the right in Fig. 2, with guidance by the guide pin 48 and guide groove 50, until the guide pin 4~ enters between the legs 53 of the guide groove, whereafter the grinding wheel 3S can be moved down against the rotating button 6 for grinding or dressing the same to its desired shape. The grinding head 37 is there-after returned to the starting position, and the holding plate 4 is released from the driving disc by effecting overpressure between the driving disc 13 and the holding plate 4. By means of the air cushion thereby formed therebetween, the holding plate 4 can be moved rapidly and simply for setting the next button to be ground in the position directly beneath the folded-down centering device 29. After locking of the holding plate with the driving disc 13 and folding up of the centering device 29, grinding of said button can commence.-In this simple and rapid, but accurate manner all buttons of the bit then can be ground.
The present invention is not restricted to the embodiment described above and shown in the drawings, but can be altered I ~ 6~3~33 and modified in many different ways within the scope of the invention idea deEined in the at-tached claims. Instead of the dovetail guide groove, for example, a through slit can be formed in the angular support, through which slit a threaded pin connected to the bearing holder 41 can extend and be locked on the lower side of the angular support by means of a sliding disk and nut.
When button bits w~re being introduced about ten years ago, the general understanding was that this type of bits had not to be reground, but could be used -to complete wear of -the buttons, whereafter the bit could be discarded. This idea has now been abandoned entirely, because experience clearly has shown that a much better drill economy is achieved by grinding the buttons and restoring their original spheric shape wi-th uniform interspaces. Hereby the demand has arisen to be able to regrind button bits, which demand latterly has grown substantially due to the ever increasing extent of using button bits instead of bits of X- and cross-type.
It was found almost impossible, however, to satisfy this demand by regr~inding button bits with known technique, at which the buttons are manually dressed by a hand-held grinder.
The method is complicated and troublesome, and it yields fully sa-tisfactory results only in a few cases, because in most cases it is not only the buttons which have to be restored to original shape, but also the lower surface of the bit body must be re~-tored which often is exposed to impact stresses and non-uniform wear. This implies that almost always steel ~ ~ ~8033 ma-terial about the button must be removed before the buttons can be dressed to the intended shape. It was tried to remove the steel material about the buttons by milling and grinding.
Milling, however, has proved tedious and, besides, requires complex machines. It was, therefore, preferred to remove the material in question by grinding with the same hand-held grinder, which is used for dressing the buttons. Grinding with such a grinder shows disadvantages, too, for example poor cutting pace, which renders also grinding a tedious method, not the least because very often the grinding wheel has to be replaced by another one, and also because there is risk that cracks will develop in the cemented carbide button,due to the great difficulties in arranging satisfactory cooling for a hand-held grinder. A further disadvantage of manual grinding is that grinding dust, which always forms at grinding, can be sucked oEf only with difficulty. Moreover, it is very difficult with a hand-held grinder to bring about the correct shape of the button. Correct shape, however, is of great importance for the penetration rate and the lifè of the button bit.
The present invention, therefore, has the object to provide for the grinding and regrinding of button bits a mechanical method, which does not involve the aforesaid diasadvantages, but renders much more rapid grinding possible, and which is less complicated than the known art in this field, which method nevertheless imparts to the but-ton the desired spherical or, more correctly, semi-spherical shape. A further ob;ect of the 7 ~ 3 3 in~ention is to produce an apparatus for carrying out the method, which apparatus is (~esigned so that it can be handled without difficulty even by semi-skilled operators.
According to the present invention, then, there is provided a method of restoring the shape of worn button bits by grinding each one of the buttons, wherein the button in the bit to be ground is caused to rotate substantially about its own longitudinal axis, and that thereafter grinding is carried out in two subseque:nt steps for removing material about the button in the first step by a first grinding wheel, and for forming the button in the second step by a second grinding wheel.
According to a further aspect of the present invention, there is also providea an apparatus for restoring the shape of w~rn button bits by grin~ing each one of the buttons, the apparatus comprising a rotary table, on which the button bit can be fixed in ~ position in which the button to be ground has its longitudinal axis substantially aligned with the rotational axis of the rotary table, and two grinding wheels arranged each on a spindle in a common grinding head, the grinding head being movable and rotatable in order to move first the first grinding wheel and then the second grinding wheel to a grinding position for grinding the button bit in two subsequent steps.
' .
According to yet another aspect of the present invention, there is further provided an apparatus for grinding a worn button bit having a plurali1:y of buttons formed thereon, the apparatus comprising me~ms for rotating the button bit holding means for retaining the button bit on the rotating means in a position for grinding with the button to be ground having its longitudinal axis aligned with the rotational axis of the rota1ing means, and first and second spaced apart grinding means movably mounted proximal the button bit for actuation be-ween grinding and inoperative positions thereof, wherein the first first and second grinding means may be successively moved into the grinding positions thereof for grind:ing the button bit and successive ones of the plurality of buttons.
:' .
Embodiments o:E the present invention will now be described in greater detai:L with reference to the accompanying drawings, in which Fig. l is a perspecti~e view of an apparatus or machine according to the invention, Fig. 2 is a front view of the upper part of the machine, Fig. 3 is a section of a fixture seen obliquely from below, and Fig. 4 is a vertical section on an enlarged scale through .~.i.~
.~
. ' .
.: .
3b the grinding table of the machine.
The apparatus or machine, which is illustrated in the drawings only by way of exarlple, comprises a stand 1 in the form of a table with a suitable w~rking height and intended to be placed on a support. An edging 2 extends all about the table top 3 proper. On the upper surface of the table top a holding plate 4 is attached which carries removably a fixture 5, in which a butlon bit 7 with buttons 6 to be reground is unmovably chucked in a holder 10, which is provided with substantially V-shaped seat 9 and chucking screw 8, and which can be set in different angular positions and be locked by a locking screw 11 in every position set.
~.
-- 1 3 6~33 The holding plate 4 rests with its surface-ground lower surf-ace 12 (Fig. 4) on a driving disc 13, which is also surface ground and has a su~stantially smaller diameter than the holding plate 4, so that the latter can be moved radially in relation to the driving disc 13 within the area defined by a circum-ferential flange 14 on the lower side of the holding plate.
The driving disc 13 is connected to a vertical shaft 15, which is supported and guided in a bearing bushing or holder 18, which is attached to the lower surface of the table top by means of a support plate 17 fastened with screws in carrier beams 1~. Said bearing bushing or holder 18 extends above the table plane and is enclosed by a protective edging 19, which like the edglng 2 prevents cooling liquid and the like from running off the table top 3 other than through an outlet tnot shownj provided for this purpose.
The vertical shaft 15 connected to the driving disc 13 is driven by a motor 20, which is suspended in the stand 1 and can be an electric, pneumatic or hydraulic one, via a miter gear 21, which preferabiy shall permit speed control, a coupling 22 and a swivel coupling-23 with an inlet 26, which via a channel 24 in the swivel coupling 23 and in the shaft 15 communicates with the space between the holding plate 4 and -the driving disc 13, which is sealed against said plate by a sealing ring 25. The said inlet 26 is connected via a conduit 27 and a hand- or foot-oper-ated valve (not shown) to a generator producing overpressure and underpressure, by means of which generator (not shown) and valve ~ ~ 6~033 an overpressure or underpre~sure can be established in said space between the holding plate 4 and the driving disc 13.
The overpressure is intended to detach the holding plate 4 from the driving disc 13 and to form an air cushion therebetween, which substantially facilitates the moving of the holding plate 4 relative to the rotation centre 28 of the driving disc. The u:nderpressure, in the form of a vacuum, is intended to rigidly connect the holding plate 4 to the driving disc 13 and thereby to cause the holding plate 4 to rotate at the same speed as the driving disc 13.
The holding plate ~ being easily movable relative to the driving disc 13, the fi.xture 5 and the button bit 7 can be set rapidly in relation to the rotation centre 28 of the driving disc. In order to additionally facilitate accurate centering o the button 6 to be ground, the present machine is equipped with a centering device 29, which is supported so as to be positively adjustable in its longitudinal direction by an arm 30. Said arm is mounted without ].ateral play proper in an upright 31 attached unmovably to the stand table 1 and is foldable downward t~ a position which is determined by a stop member 32 provided in said upright 31. In this position the longitudinal axis of the centering device aligns with the rotation axis 28 of the driving disc, and its preferably concave curved lower surface 33 indicates the height position for the button to be ground, and which, thus, can be rapidly and simply adjusted to the machining position intended~
., ~ .
Z 1 6gO33 5a The present machine further comprises two grinding wheels 34, 35~ one 34 of which is .intended to remove material about the buttons ' 1 ~ 6~33 6, and the other one 35 is intended to impart to the buttons the shape desired and a profile suitable therefor. The grind-ing wheels 34~35 are arranged exchangeably each on a spindle 36, which are located in a common grinding head generally designated by 37 and are driven in common or each separately by an electric, pneumatic or hydraulic motor 38 through a belt transmission 39, shown schematically in Fig. 3, at speeds intended for the grinding wheels 34,35.
The grinding head 37 is attached non-rotary on a bushing 40, for example a ball bushing, which is mounted movably on an axle 43 rotatably mounted in bearing holders 41,42, but not rotatable relative to said axle 43. This implies that upon rotation of the axle 43 also the bushing 40 and the grinding head 37 connected thereto are rotated. Thereby also the grind-ing wheels 34,35 can be swung by a control lever 60 connected to the grinding head from the non-operative or starting position shown in Fig. 2 to the operative position shown in Fig. 1, in which posi-tion the button 6 to be ground is set by means of the centering device 29. Between the ends of the bushing and the axle 43 bellaw-like sleeves 44, for example of rubber or the like, are arranged to prevent dust and other impurities from penetrating in bewteen the bushing 40 and axle 43~
The bearing holders 41342 are supported by an angular support 45 attached on the stand table and can be arranged for parallel shifting of the axle 43, although this is not shown in the drawing. In the drawings, one bearing holder 42 is shown to be rotatably connected to its angular support 45, while the second holder 41 is shown movable by means of a set screw 46, which is provided with a wheel, in a dovetail guide groove 47 in the associated angular support 45. By means of the set screw 46, thus, it is possible to change the pOSitiQn of the grinding wheels in relation to the rotation axis of the driving disc.
Thereby the present machine can also be adapted to a certain extent to different button diameters.
Owing to the fac-t that the grinding head can be moved and swung, each of the two spaced grinding wheels 34,35 can be moved to and from the operative or grinding position. For rendering possible a rapid and accurate setting of the respect~
ive grinding wheel in this position, a guide pin 48 is provided which is connected to the stand table 1 and by a guide roller co-operates with a substantially U-shaped guide groove 50 in a guide plate 51 connected to the grinding head 37. The legs 52,53 of said guide groove which are located in spaced rela-tionship corresponding to the distance between the centres of the spindles 36 and have a width corresponding to the guide roller 49, thereby fix the respective grinding wheels 34 and 3S
in a vertical ~lane extending -through the grinding position and,thus,guide the grinding wheel fixed in this plane while it is moving to and from the bit and the button to be ground, l.e. to and from the grinding position.
Ths grinding head 37 preferably shall be balanced so that it more or less by itself tends to set itself in the non-operative or starting position shown in Fig. 2, in which position the guide pin 48 assumes a position substantially halfway between the legs 52,53 of the guide groove. Owing to the co-operation ~ ~ 6 ~ 3 .~.
between the guide groove and the guide pin, it is, thus, simple to move one or the other of the grinding wheels 34,35 from said starting position by the;control lever 60 to grinding position and there with the grinding wheel 34 to grind off material about the centered and rotating button 6 and thereafter with the grinding wheel 35 to grind or dress the button or-j more precisely, its button end to the desired semi-spherical shape. The grinding force required is supplied by means of the control lever 60.
In Fig. 2 the grinding head 37 is shown in its starting position for a grinding operation. When the button in the bit to be ground has been centered by means of the centering device 29, so that its axis substantially coincides with the rota-tion axis 28 of the driving disc, the said hand- or foot-operated valve is actuated to connect the holding plate 4 and the driving plate with one another by underpressure and thereby to cause the holding plate 4, t-he fixture 5 and the bi-t 7 chucked therein to rotate abou-t the axis of the centered button. There-after~ and after the centering device 29 has been Eolded up, the control lever 60 is moved downward and possibly slightly to the left in Fig. 2, whereby the guide pin 48 by co-operation with the guide groove 50 moves the grinding head 37 to the left until the guide pin 48 can enter between the legs 52 of the guide groove, whereafter the grinding head 37 is swung down by the co~trol lever 60 to effect contact of the grinding wheel 34 with the bit and to remove material about the centered button 6.
Upon the downward swing of -the grinding head 37, a switch or , ~ 1~8~33 g the like (not shown) can be actuated automatically in order to effect in known manner cooling of the grinding zone by a cooling liquid ejected by a suitable nozzle (not shown).
After the necessary amount of material has been removed about the button 6, the grinding head 37 is moved up from the bit 7.
During this movement the cooling preferably automatically is interrupted. The grinding head then is moved to the right in Fig. 2, with guidance by the guide pin 48 and guide groove 50, until the guide pin 4~ enters between the legs 53 of the guide groove, whereafter the grinding wheel 3S can be moved down against the rotating button 6 for grinding or dressing the same to its desired shape. The grinding head 37 is there-after returned to the starting position, and the holding plate 4 is released from the driving disc by effecting overpressure between the driving disc 13 and the holding plate 4. By means of the air cushion thereby formed therebetween, the holding plate 4 can be moved rapidly and simply for setting the next button to be ground in the position directly beneath the folded-down centering device 29. After locking of the holding plate with the driving disc 13 and folding up of the centering device 29, grinding of said button can commence.-In this simple and rapid, but accurate manner all buttons of the bit then can be ground.
The present invention is not restricted to the embodiment described above and shown in the drawings, but can be altered I ~ 6~3~33 and modified in many different ways within the scope of the invention idea deEined in the at-tached claims. Instead of the dovetail guide groove, for example, a through slit can be formed in the angular support, through which slit a threaded pin connected to the bearing holder 41 can extend and be locked on the lower side of the angular support by means of a sliding disk and nut.
Claims (33)
1. A method of restoring the shape of worn button bits by grinding each one of the buttons, wherein the button in the bit to be ground is caused to rotate substantially about its own longitudinal axis and that thereafter grinding is carried out in two subsequent steps for removing material about the button in the first step by a first grinding wheel, and for forming the button in the second step by a second grinding wheel.
2. A method as defined in claim 1, wherein the grinding wheels are moved together to and from the button.
3. An apparatus for restoring the shape of worn button bits by grinding each one of the buttons, said apparatus comprising a rotary table, on which the button bit can be fixed in a position in which the button to be ground has its longitudinal axis substantially aligned with the rotational axis of the rotary table, and two grinding wheels arranged each on a spindle in a common grinding head, the grinding head being movable and rotatable in order to move first the first grinding wheel and then the second grinding wheel to a grinding position for grinding the button bit in two subsequent steps.
4. An apparatus as defined in claim 3, wherein the table consists of a driven driving disc and a holding plate thereon for the button bit, which holding plate is radially movable relative to the driving disc and can be locked to it by means of underpressure.
5. An apparatus as defined in claim 4, wherein the holding plate is detachable from the driving disc by means of overpressure, which also Eorms an air cushion, on which the holding plate is movable relative to the driving disc.
6. An apparatus as defined in claim 5, wherein the grinding head is connected to a bushing which is movable along an axle but not rotatably connected to said axle.
7. An apparatus as defined in claim 6, wherein said axle is adjustable relative to the rotational axis of the table for adapting the apparatus to different button diameters.
8. An apparatus as defined in claim 7, wherein the table is driven by a motor via at least one gear and a swivel coupling.
9. An apparatus as defined in claim 8, wherein the swivel coupling is connected to a device for effecting underpressure and overpressure for locking and, respectively, releasing the holding plate of the table from the driving disc thereof.
10. An apparatus for grinding a worn button bit having a plurality of buttons formed thereon, said apparatus comprising:
means for rotating said button bit;
holding means for retaining said button bit on said rotating means in a position for grinding with the button to be ground having its longitudinal axis aligned with the rotational axis of said rotating means; and first and second spaced apart grinding means movably mounted proximal said button bit for actuation between grinding and inoperative positions thereof, wherein said first and second grinding means may be successively moved into said grinding positions thereof for grinding said button bit and successive ones of said plurality of buttons,
means for rotating said button bit;
holding means for retaining said button bit on said rotating means in a position for grinding with the button to be ground having its longitudinal axis aligned with the rotational axis of said rotating means; and first and second spaced apart grinding means movably mounted proximal said button bit for actuation between grinding and inoperative positions thereof, wherein said first and second grinding means may be successively moved into said grinding positions thereof for grinding said button bit and successive ones of said plurality of buttons,
11. The apparatus of claim 10 wherein said means for rotating said button bit comprise a rotatable platform including a rotatable disc and a plate member provided thereon, said plate member being transversely movable relative to the rotational axis of said disc to facilitate adjustments to the positioning of said button bit and adapted for locking to said disc by means of negative air pressure therebetween when said button bit is positioned for grinding.
12. The apparatus of claim 11 wherein transverse movements of said plate member relative to the rotational axis of said disc are facilitated by positive air pressure forming an air cushion between said plate member and said disc.
13. The apparatus of claim 12 including conduit means communicating with the interface between said disc and said plate member for introducing said negative and positive air pressures therebetween.
14. The apparatus o- claim 13 wherein said rotat-able disc is driven by motor means via a shaft connected at one end thereof to said disc.
15. The apparatus of claim 14 wherein said conduit means extend axially through said shaft and thereafter through said disc to communicate with said interface.
16. The apparatus of claim 15 wherein swivel joint means are provided between said shaft and said motor means, said conduit means opening through said swivel joint means for connection to a source of positive and negative air pressure.
17. The apparatus of claim 15 wherein said first and second grinding means each comprise a grinding wheel provided at the end of a respective spindle, said first grinding means being adapted for grinding said button bit to remove material about the button being ground, and said second grinding means being adapted for grinding the button itself for restoring its shape.
18. The apparatus of claim 17 wherein said spindles extend from a common grinding head including means therein for rotating said grinding wheels.
19. The apparatus of claim 18 wherein said grinding head is non-rotatably connected to a rotatable axle for lateral movement along said axle, whereby said grinding head may be moved along said axle to align either of said first and second grinding means with said button bit and then pivoted to bring the aligned grinding means into said grinding position thereof for grinding purposes.
20. The apparatus of claim 19 including guide means for guiding the lateral and pivotal movements of said guiding head.
21. The apparatus of claim 19 wherein said axle is pivotable about one end thereof in a plane substantially parallel to the plane of said rotating means for movement of said grinding head towards, and away from the rotational axis of said rotating means, thereby facilitating the grinding of buttons having different diameters.
22. The apparatus of claim 21 wherein said plate member is substantially circular in shape and includes a peripheral flange extending axially in the direction of said disc to limit the scope of transverse movement of said plate member relative to the rotational axis of said disc.
23. The apparatus of claim 22 wherein said disc is sealed against said plate member by means of a sealing ring extending about the peripheral edge of said disc adjacent to said plate member.
24. The apparatus of claims 21, 22 or 23 wherein the mutually adjacent surfaces of said disc and plate member are ground for a close fit therebetween.
25. The apparatus of claim 21 wherein said holding means comprise a chuck adapted for connection to said plate member, said chuck being further adapted to securely hold said button bit and to permit adjustments to the attitude thereof to align the longitudinal axis of the button to be ground with said rotational axis of said rotating means.
26. In an apparatus for grinding worn button bits having at least one button formed thereon, said apparatus including a rotatable platform and means for holding said button bit thereon in a position for grinding, the improve-ment wherein said rotatable platform comprises a rotatable disc and a plate member for supporting said holding means provided on said disc, said plate member being transversely movable relative to the rotational axis of said disc to facilitate adjustments to the positioning of said button bit and adapted for locking to said disc by means of negative air pressure therebetween when said button bit is positioned for grinding.
27. The apparatus of claim 26 wherein -transverse movements of said plate member relative to the rotational axis of said disc are facilitated by positive air pressure forming an air cushion between said plate member and said disc.
28. The apparatus of claim 27 including conduit means communicating with the interface between said disc and said plate member for introducing said negative and positive air pressures therebetween.
29. The apparatus of claim 28 wherein said disc is driven by motor means via a shaft connected at one end thereof to said disc, said conduit means extending axially through said shaft and through said disc to communicate with said interface.
30. The apparatus of claim 29 including swivel joint means provided between said shaft and said motor means, said conduit means opening through said swivel joint means for connection to a source of positive and negative air pressure.
31. The apparatus of claim 30 wherein said plate member is substantially circular in shape and includes a peripheral flange extending axially in the direction of said disc to limit the scope of transverse movement of said plate member relative to the rotational axis of said disc.
32. The apparatus of claim 31 wherein said rotatable disc is sealed against said plate member by means of a sealing ring extending about the peripheral edge of said disc adjacent to said plate member.
33. The apparatus of claims 30, 31 or 32 wherein the mutually adjacent surfaces of said disc and plate member are ground for a close fit therebetween.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7907575A SE428541B (en) | 1979-09-12 | 1979-09-12 | Arrangement for restoring the shape of worn boring bits by grinding |
| SE7907575-0 | 1979-09-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1168033A true CA1168033A (en) | 1984-05-29 |
Family
ID=20338814
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000359748A Expired CA1168033A (en) | 1979-09-12 | 1980-09-03 | Method and apparatus for grinding button bits |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1168033A (en) |
| SE (1) | SE428541B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004080651A1 (en) * | 2003-03-10 | 2004-09-23 | Atlas Copco Secoroc Ab | A grinding machine. |
| WO2008133581A1 (en) * | 2007-04-25 | 2008-11-06 | Atlas Copco Secoroc Ab | Method and arrangement for grinding button drill bits, and an abrasive wheel for carrying out the method |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4858388A (en) * | 1986-07-25 | 1989-08-22 | Bice Keith C | Restoration or drill buttons |
| GB2381768B (en) | 2000-07-10 | 2004-02-25 | Cme Blasting & Mining Equip | Improved grinding apparatus |
| SE527994C2 (en) * | 2004-12-15 | 2006-08-01 | Atlas Copco Secoroc Ab | Adjusting arrangement for a grinding machine for grinding pin drill bits |
-
1979
- 1979-09-12 SE SE7907575A patent/SE428541B/en not_active IP Right Cessation
-
1980
- 1980-09-03 CA CA000359748A patent/CA1168033A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004080651A1 (en) * | 2003-03-10 | 2004-09-23 | Atlas Copco Secoroc Ab | A grinding machine. |
| WO2008133581A1 (en) * | 2007-04-25 | 2008-11-06 | Atlas Copco Secoroc Ab | Method and arrangement for grinding button drill bits, and an abrasive wheel for carrying out the method |
Also Published As
| Publication number | Publication date |
|---|---|
| SE428541B (en) | 1983-07-11 |
| SE7907575L (en) | 1981-03-13 |
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