US2855917A - Dressing attachment for surface grinders - Google Patents

Description

Oct. 14, 1958 A. A. BERG DRESSING ATTACHMENT FOR SURFACE GRINDERS 2 Sheets-Sheet 1 Filed April 4, 1957 Oct. 14, 1958 A. A. BERG 55,

DRESSING ATTACHMENT FOR SURFACE GRINDERS Filed April 4, 1957 2 Sheets-Sheet 2 RTHUR A. BERG United States Patent DRESSING ATTACHMENT FUR SURFACE GRINDERS Arthur A. Berg, Chicago, Ill.

Application April 4, 1957, Serial No. 650,756

6 Claims. ((11. 125-41) The improved dressing attachment comprising the present invention has been designed for use primarily in connection with surface grinders for truing a grinding wheel or disk associated therewith and having a bevelled peripheral edge which may be of V-shape cross sectional configuration or which may have a flat or cylindrical surface between adjacent oppositely bevelled portions. The invention is, however, capable of other uses and the same may, if desired, with or without modification, be employed for the dressing or truing of abrasive wheels hav- 'ing cylindrical and/or frusto conical operating surfaces and which are mounted upon arbors associated with bench grinders and a wide variety of machines other than surface grinders. Irrespective, however, of the particular use to which the invention may be put, the essential features thereof are at all times preserved.

The objects of the invention are manifold and principal among them is the provision of a dressing attachment for surface grinders and the like which is extremely simple in its design as compared with other dressing attachments designed for the same type of truing operations, which requires a minimum amount of machining in the manufacture thereof and which, therefore, may be produced at a relatively low cost.

Another important object of the invention is to provide a dressing attachment of this character which, when applied to the machine with which it is associated for grinding wheel dressing purposes, may be manipulated throughout a wide range of movements to true any or all of the angular operating surfaces on the grinding wheel or disk without necessitating removal of the work on which the grinding wheel has previously been operating from its position on the machine table or slide rest for clearance purposes, and which in most instances will not disturb the previous arbor adjustment relative to the work.

A still further object of the invention is to provide a dressing attachment for grinding wheels which, during actual application to a grinding wheel for truing purposes, may be manipulated by the thumb and forefinger of one hand, both for causing the dressing tool proper to traverse the surface on the grinding wheel undergoing truing and for advancing the tool toward the wheel.

Yet another object of the invention is to provide a dressing attachment of the character briefly outlined above which may quickly and easily be applied to a surface grinder or other grinding machine, brought to-an approximate truing position with respect to the grinding wheel I undergoing dressing, and thereafter adjusted and set for truing the bevelled edges on the opposite sides of the grinding wheel, utilizing but a single diamond point or similar truing element.

The provision of a dressing tool which is rugged and durable and which, therefore, will withstand rough usage one which is possessed of a minirrrum number of moving parts and which, therefore, is unlikely to get out of order; one which is small and compact and which, therefore,

pccupies but little space on the machine table or slide rest associated with the surface grinder with which it may be associated; one which does not require any particular degree of skill for its successful operation; and one which otherwise is well adapted to perform the services required of it are further desirable features which have been borne in mind in the production and development of the present invention.

Numerous other objects and advantages of the invention, not at this time enumerated, will become more readily apparent as the nature of the invention is better understood.

In the accompanying two sheets of drawings forming a part of this specification a preferred embodiment of the invention has been shown.

In these drawings: I

Fig. l is a fragmentary perspective view of a surface grinder in the vicinity of the table portion thereof and showing one of the improved dressing attachments constructed in accordance with the principles of the present invention operatively mounted thereon in truing relation with respect to a grinding wheel;

Fig. 2 is an enlarged top plan view of the dressing attachrnent showing the truing element thereof operatively applied to one bevelled surface on a grinding wheel;

Fig. 3 i sa plan view similar to Fig. 2 showing the truing element operatively applied to the other bevelled sur face of the grinding wheel;

Fig. 4 is a side elevational view of the structure shown in Fig. 2; j

Fig. 5 is a sectional view taken substantially along the line S5 of Fig. 4;

Fig. 6' is a sectional View taken substantially along the line 6-6 of Fig. 4;

Fig. 7 is a sectional view taken substantially along the line 77 of Fig. 4; and

Fig. 8 is a fragmentary perspective view of a portion I of the machine base.

Referring now to the drawings in detail and in particular to Fig. l, a dressing attachment constructed in accordance with the principles of the present invention has been designated in its entirety at 10 and is shown as being operatively installed upon the magnetic bed plate 12 of a surface grinder, the latter being designated in its entirety at 14. The surface grinder 14 is purely conventional in its design and no claim is made herein to any novelty as.- sociated with the same and for this reason but little description thereof will sufiice for an understanding of the manner in which the present dressing attachment-is 'associated therewith and the adjustments of the grinder which may be necessary to bring the truing tool of the present invention into operative position with respect to a grinding wheel which forms a component part of the surface grinder and the conical surfaces .of which are .to be dressed by the attachment. Accordingly, the surface grinder 14 includes the usual movable work carriage-assembly 16 to which there is clamped at 18 the previously mentioned magnetic bed plate 12 which moves .bodil-y with the carriage. The bed plate 12 carries at its'rear edge the usual aligning bar 20. The bed plate 12, upon energization of the electromagnetic attraction devices (not shown) associated therewith, is adapted to attract thereto and firmly and fixedly .hold thereon a workpiece 22 which is to be operated upon by a grinding wheel'2'4 suitably mounted on a rotating arbor .26 and having associated therewith oppositely facing bevelled operating surfaces 24a and 24b respectively (Figs. 3 and 4). The arbor 26 is rotatably mounted in a hub-like structureZS supported on a vertically reciprocable back plate 30 which is .slida'bly disposedin vertical guideways 32 supported on a column 34 which constitutes a part of the stationary machine framework. The grinding wheel24 overliesthe carriage assembly 16 and bed plate 12 and the arbor 26 on which it is mounted is adapted to be driven through a suitable train of gearing-or other power train leading to the drive shaft of an electric motor (not shown) and which .may be appropriately mounted on the machine framework.

The grinding wheel 24 is adapted to be brought Into the horizontal cutting plane of the workpiece under the con trol of a handwheel 42 which effects the raising and lowering of the back plate 30 and consequently of the hub 28 and wheel 24. Similarly, the workpiece is adapted to be brought into the vertical cutting plane of the grinding wheel by means of a second handwheel 44 which controls the forward and backward movements of the carriage assembly 16. Lateral movement of the Carriage assembly 16 to cause the grinding wheel 24 to traverse the workpiece is effected under the control of a third hand wheel 46.

The improved dressing attachment involves in its general organization abase 50 in the form of a rectilinear block of steel which is preferably square in horizontal cross section and of-appreciable thickness so as to be capable of having formed in the upper face thereof a relatively deep circular socket 52. The base 50 supports a vertically extending pedestal 54, the lower end of which fits snugly within the socket 52 but which is rotatable therein and is capable of being clamped in any one of an infinite number of adjusted positions by means of a clamping screw 56 which passes through a threaded bore 58 (Fig. 6) formed in the base 50 and communicating with the socket 52. A cylindrical brass plug 60 is interposed between the inner end of the clamping screw 56 and is slidable in the bore, the plug receiving the thrust of the screw and thus preventing scoring or otherwise marring of the outer cylindrical surface of the pedestal 54. The pedestal 54 is of hollow cylindrical sleeve-like design and is adapted to adjustably support at selected elevations above the base 50 a guide block assembly including a guide .block proper 62 from which there extends downwardly a cylindrical shank or column 64.

The column or shank 64 is telescopically received in the open upper end of the cylindrical pedestal 54 and is slidable vertically in the pedestal. In order to lock or clamp the shank 64 in any desired position of vertical adjustment, a series of clamping screws 66, of which there may be four in number, extend radially inwardly through the cylindrical wall of a clamping collar 68 as best seen in Fig. 7, are threadedly received in radial bores 70 provided in the collar, and project into a series of bores 72 formed in the pedestal 64 near the upper end thereof and in register with the bores 70. A brass plug 76 slidably disposed in three of the bores 72 is interposed between the inner end of the adjacent clamping screw 66 and the outer surface of the shank 64 and serves to transmit the clamping effect of its respective clamping screw to the shank. One of the screws 66 is larger than the others and has a reduced end 77 which projects into a vertical keyway 78 provided in the outer surface of the shank 64 and serves to prevent angular turning movement of the shank relative to the hollow cylindrical pedestal 54 within which it is mounted.

The guide block 62 is of elongated rectilinear configuration, it being rectangular in both horizontal and vertical cross section. Formed centrally in the upper face of the block 62 is a dovetail groove or guideway 80 (Fig. 5) which extends the entire length of the block. The guide block 62 is mounted substantially centrally on the upper end of the cylindrical shank 64 by means of a pair of attachment screws 81, the heads of which are countersunk in the bottom wall of the dovetail groove 80. Mounted for longitudinal reciprocation in the dovetail groove 80 is a dressing tool holder 82 which is trapezoidal in transverse cross section and which fits snugly within the dovetail groove 80 and is capable of reciprocation therein longitudinally of the guide block 62.

The steel metal of the dressing tool holder 82 and of the guide block 62 at least in the vicinity of the guideway 80 is preferably case hardened and the dimensional tolerance between the two parts is maintained at a minimum so that the holder 82 will slide freely within the guideway 80 with no appreciable misalignment of axes and with no appreciable wear between the parts.

The side portions 84 of the guide block 62, created by virtue of the provision of the dovetail grove 80 are formed with elongated slots 86 therein which slots afford a clearance for a commercial dressing tool shank 88 which projects through the two slots and through the holder 82 and carries a diamond dressing point 90 at its forward end. The shank 88, with the diamond point 90 operatively mounted therein is commercially available in an unthreaded condition and, according to the present invention, in constructing the dressing attachment 10, the shanks 88 may be purchased and the cylindrical bodies thereof threaded as shown at 92 for threaded reception in a transverse threaded bore 94 provided in the holder 82. The diameter of the shank 88 is less than the width of the slots 86 so that the shank will have freedom of movement in the slots upon reciprocation of the tool holder 82 within the dovetail groove 80. An operating knob 96 is telescopically received over the rear end of the shank 88 and is formed with a knurled surface to facilitate turning thereof for advancing or retracting the I shank and consequently the diamond dressing point 90 during grinding wheel dressing operations.

For precision setting or adjusting of the dressing attachment to produce the desired angular contour or contours ,on the grinding wheel 24, the upper surface of the base 50 in the vicinity of the rim of the socket 52 may be provided with a series of indicia 98 representing the angular adjustment of the pedestal 54 relative to the block 50 and the pedestal may have formed thereon a reference mark 100 designed for cooperation with the various indicia 98.

In the application of the dressing attachment 10 to the surface grinder 14 and its subsequent use in truing the surfaces 240: and 24b of the grinding wheel 24, the base 50 of the assembled structure 10 is first applied to the magnetic bed plate 12 with one edge thereof abutting againstthe front side of the aligning bar 20. This application of the base 50 to the bed plate 12 may be made without disturbing the position of the workpiece 22 on which the grinding wheel 24 has previously been operating. For illustrating purposes, the workpiece 22 has been shown as being in the form of a rectilinear block'of metal across the upper face of which it is desiredto produce a trough such as the one shown at 22a or to finish the side walls of such a trough which has previously been machined in the block 22.

The various grinder controls 42, 44 and 46 may be manipulated to disassociate the grinding wheel 24 on the spindle or arbor 26 from the workpiece prior to application of the dressing attachment to the grinding wheel. It will be understood that for workpieces having small height, i. e., a height which, when added linearly to the radius of the grinding wheel 24, is less than the lowermost elevation to which it is possible to bring the diamond dressing point 90, the grinding wheel arbor 26 will have to be elevated to attain the necessary positional relation between the grinding wheel and the truing point 90, the usual practice being to maintain the axis of the grinding wheel slightly above the horizontal axis of the diamond point. Where relatively tall workpieces are involved, it may be necessary to raise the level of the grinding wheel arbor 26 but, in any instance, it is only necessary to manipulate the surface grinder controls to a degree sufficient to cause the grinding wheel 24 to clear the work.- piece 22 and, if necessary, to bring the wheel to the minimum elevation of the truing point 90.

Since the plane of the grinding wheel 24 is normal to the axis of the arbor 26, and since the aligning bar 20 extends in a direction which is parallel to the plane of the grinding wheel, the indicia 98 and reference mark 100 may be employed effectively to set the desired angle of the dressing tool shank 88. In the illustrated embodiment of the invention, the bevelled surfaces 24a and 24b on the grinding wheel are disposed at a 45 angle with respect to the plane of the grinding wheel, i. e., at an angle of 90 from each other, and thus the reference mark 100 may be brought into register with one of the indicia labelled "45 and the clamping screw 56 tightened against the outer surface of the pillar 54. After the grinding wheel 24 has been brought to the desired elevation so that it will clear the workpiece 22, the vertical position of the cylindrical shank 64 of the guide block assembly is adjusted to bring the axis of the dressing tool shank 88 to a level where it slightly underlies the horizontal plane of the grinding wheel arbor 26 and the various clamping screws 66 are effectively tightened against the outer cylindrical surface of the shank 64 with the reduced end 77 of the larger screw 66 extending into the keyway 78 so that the axis of thedressing tool shank 88 will assume its proper 45 position of angularity with respect to the plane of the grinding wheel 24.

The actual dressing operation is performed, for instance, on the bevelled surface 24a (Fig. 3) by manpulation of the knob 96 on the dressing tool shank 88, the knob being turned so as to thread the shank 88 through the threaded bore 94 in the holder 82 in one direction or the other and bring the diamond truing point 90 to the proper depth of cut for truing of the surface 24a. Thereafter, by reciprocating the holder 82 in the dovetail groove 80 from side to side, utilizing the knob 96 to effect such reciprocation, the point of the dressing tool may be caused to traverse the surface 24a and thus effect the truing operation. During such reciprocation, and without requiring the use of. two hands or removal of the thumb and forefinger from the knob 96, the dressing tool may be advanced for successive and deeper cuts across the surface 24a.

After the surface 24a has been brought to the desired degree of flatness along the slant height of the cone frustum, and it is desired to proceed with the truing of the surface 24b, the diamond point 90 may be brought to the necessary truing relationship with respect to this latter surface merely by performing a single adjustment upon the dressing attachment 10, namely, readjustment of the angularity of the pedestal 54 with respect to the base 50 so that the reference mark 100 moves into register with the other indicia 98 labelled 45 in the adjacent quadrant of the scale. This, of course, will be accomplished by loosening the clamping screw 56, making the adjustment, and thereafter tightening the screw to effectively clamp the pedestal 54 in its adjusted position. T 0 effect the above described changeover during which the pedestal and the entire asembly which it supports is swung throughout an angle of 270 relative to the base 50, it is not necessary to disturb the position of either the base or the workpiece 22 or to effect any adjustments of the operating mechanism associated with the bench grinder 14. The truing operation is carried out on the surface 24b in the manner previously described in con nection with the truing of the surface 24a.

After the grinding wheel has been brought to the desired degree of truness, both as regards the surface 24a and the surface 2%, the dressing attachment may be removed from the bed plate 12 by deenergization of the bed plate magnet or magnets and the workpiece 22 left in position. After reenergization of the bed plate magnets, the surface grinder controls 42, 44 and 46 may be manipulated in the usual manner of operation to cause the grinding Wheel 24 to resume its abrading operations on the workpiece.

The operations which are performed upon any particular grinding wheel will, of course, vary according to the specific conditions encountered, as, for example, the degree of bevel of the surfaces 24a and 24b, the width of the bevelled surfaces, the distance at which the axis of rotation of the pedestal 54 is positioned from the periphery of the grinding wheel 24, and the amount by which the axis of rotation of the pedestal is offset from the plane of the grinding wheel. In most instances, where it is possible to do so, the block 50 will be positioned on the bed plate 12 so that it lies in the plane of the grinding wheel and sufficiently remote from the periphery of the wheel that when the dressing tool holder 82 is in either of its extreme positions, the assembly may be swung in one direction or the other through an angle of 270 to bring the diamond or other dressing point to av cutting position against either surface 24a or 24b and to allow for a full stroke of the dressing point across the surface undergoing truing. In other words the effective stroke of the holder 82, as limited by the length of the slots 86, must be sufliciently long as to permit the dressing point to fully embrace both bevelled surfaces 24a and24b when in operative register therewith. The minimum length of the stroke of the holder 82 for effective wheel truing operations on a wheel having dual 45 bevelled surfaces may be expressed by the equation where L is the effective length of the stroke of the holder 82, Y is the distance on the plane of the grinding wheel at which the axis of rotation of the pedestal 54 is spaced from the periphery of the wheel, and W is the slant height of the frusto conical surfaces undergoing truing. In the manufacture of the guide block 84, the slots 86 should be machined to permit a dressing tool holder stroke which is somewhat longer than that expressed by the above equation.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit of the invention. Only insofar as the invention has been particularly pointed out in the accompanying claims is the same to be limited.

Having thus described the invention what I claim as new and desire to secure by Letters Patent is:

1. In a dressing device for the abrasive wheel of a grinding machine, in combination, a base plate adapted to be fixedly secured to a portion of the machine in the vicinity of said abrasive wheel, there being an upwardy presented open socket having a cylindrical wall formed in said base plate, a pedestal having its lower end rotatably mounted in said socket, means for clamping said lower end of the pedestal within the socket in any desired position of rotational adjustment, said pedestal being in the form of a cylindrical member open at its upper end, a guide block having a depending shank telescopically received in said pedestal through the open upper end thereof and vertically adjustable therein, means for fixedly clamping said shank Within the pedestal in any desired position of vertical adjustment, said guide block being formed with a longitudinally extending guideway therein the axis of which extends horizontally, a dressing tool holder mounted for reciprocation in said guideway, a dressing tool shank projecting completely through said holder and carrying at its forward end a dressing tool proper and at its rear end a manipulating knob, and means limiting the amplitude of reciprocation of the holder within said guideway, said dressing tool shank and holder having threaded engagement with each other whereby said manipulating knob may be employed to effect manual reciprocation of the holder within the guideway as well as feeding movement of the dressing tool proper toward and away from a surface on the grinding Wheel undergoing truing.

2. In a dressing device for the abrasive wheel of a grinding machine, the combination set forth in claim 1.

7 wherein said guideway in the guide block is in the form of an upwardly facing groove having side walls and a bottom, and wherein said limiting means is in the form of a longitudinally extending slot in each side wall through which said dressing tool shank extends with the ends of a least one of said slots being positioned in the path of travel of the dressing tool shank so as to limit the extent of movement of the shank in either longitudinal direction relative to the guideway.

3. In a dressing device of the abrasive wheel of a grinding machine, the combination set forth in claim 1 wherein said guideway in the guide block is in the form of an upwardly facing dovetail groove the side walls of which straddle said dressing tool holder, said side walls being provided with longitudinally extending slots therein through which said dressing tool shank extends, the end of said slots being positioned in the path of movement of the dressing tool shank and constituting the means for limiting the amplitude of reciprocation of said holder.

4. In a dressing device for the abrasive wheel of a grinding machine, the combination set forth in claim 1 including, additionally, cooperating indicia and reference marking on said pedestal and base plate for indicating the angular position of the former with respect to the latter.

5. In a dressing device for truing oppositely bevelled abrading surfaces existing in the peripheral regions of a grinding wheel mounted on an arbor associated with a surface grinder having'a work supporting bed plate, in combination, a base plate adapted to be fixedly secured to said bed plate, a column projecting upwardly from said base plate and vertically and rotationally adjustable thereon, means for clamping said column in any desired position of adjustment, a guide block mounted on the upper end of said column and movable bodily therewith, said guide block being formed with a longitudinally extending guideway in the form of an upwardly facing groove which is coextensive with the longitudinal extent of the block, a dressing tool holder mounted for reciprocation in said guideway, a dressing tool shank projecting completely through said holder and carrying at its forward end a dressing tool proper and at its rear end a manipulating knob, the side wallsv of said groove in the guide block being formed with longitudinally extending slots through which said dressing tool shank extends, the 4 ends of said slots being positioned in the path of movement of said dressing tool shank and limiting the amplitude of reciprocation of the holder, the effective length of said slots being such as to permit the holder to reciprocate in a path the length of which is slightly in excess of the length L expressed in the equation:

where Y is the distance of the vertical axis of rotation of the column from the extreme periphery of the grinding wheel and W is the width of each bevelled surface on the grinding wheel, said equation being applicable when said column is clamped at an elevation which will maintain said dressing tool substantially in the plane of the grinding wheel arbor.

6. In a dressing attachment for truing an abrading surface on the abrasive wheel of a surface grinder of the like, in combination, a base plate adapted to be fixedly secured to a portion of the machine in the vicinity of said abrasive wheel, a column projecting upwardly from said base plate and vertically and rotationally adjustable there 011, means for clamping said column in any desired position of adjustment, a guide block mounted on the upper end of said column, said guide block being formed with an upwardly facing longitudinally extending guideway having side walls and a bottom and the axis of which extends horizontally, a dressing tool shank projecting completely through said holder and threaded therein for feeding movement and carrying at its forward end a dressing tool proper and at its rear end a manipulating knob, and means limiting the amplitude of reciprocation of the holder within said guideway, said limiting means being in the form of a longitudinally extending slot in each side wall through which slot the dressing took shank extends with the ends of at least one of the slots being positioned in the path of travel of the dressing tool shank so as to limit the extent of movement of the shank in either longitudinal direction relative to the guideway, said dressing tool shank and bolder having threaded engagement with each other whereby said manipulating knob may be employed to effect manual reciprocation of the holder within the guideway as well as feeding movement of the dressing tool proper toward and away from the bevelled surface on the grinding wheel undergoing truing.

References Cited in the file of this patent UNITED STATES PATENTS Sneva Mar. 2, 1948

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