US3729300A

US3729300A - Centerless grinder

Info

Publication number: US3729300A
Application number: US00087779A
Authority: US
Inventors: J Mackay; J Doran
Original assignee: Unison Corp
Current assignee: Unison Corp
Priority date: 1970-11-09
Filing date: 1970-11-09
Publication date: 1973-04-24
Anticipated expiration: 1990-04-24

Abstract

A fixture for converting a surface grinder or any machine having a grinding wheel and a support below said grinding wheel into a centerless grinder, said fixture including rotatably supported shaft means and a regulating roller mounted thereon for rotation therewith near the grinding wheel. The roller will usually rotate around an axis substantially parallel with the axis of rotation of the grinding wheel, but said roller axis may be transverse of the wheel axis. Guide means on said fixture position a workpiece between the grinding wheel and regulating roller for rotation and grinding thereby. Drive means are connected to the grinding wheel and the shaft means for effecting rotation thereof.

Description

United States Patent [1 1 Mackay et al.

[ 1 CENTERLESS GRINDER [75] Inventors: John A. Mackay, Warren; John A.

Doran, III, Hartland, both of Mich.

[73] Assignee: Unison Corporation, Madison Heights, Mich.

[221 Filed: Nov. 9, 1970 [21] App1.No.: 87,779

[52] U.S.Cl. ..51/103 R,5l/241 R [51] Int. Cl. ..B24b 5/18 [58] Field of Search ..51/103 R, 241 R [56] References Cited UNITED STATES PATENTS 1,264,129 4/1918 Reeves ..51/103 R X 1,452,508 4/1923 Hervig .l.,5l/l03 R X 1,733,091 10/1929 H01mes.. ....51/103 R X 1,733,098 10/1929 Kern 51/103 R 1,858,235 5/1932 Briney ..51/103 R X c I l 74 I I \t 1 3 [451 Apr. 24, 1-973 Primary ExaminerHarold D. Whitehead Art0rney-Wo0dhams, Blanchard, and Flynn [57] ABSTRACT A fixture for converting a surface grinder or any machine having a grinding wheel and a support below said grinding wheel into a centerless grinder, said fixture including rotatably supported shaft means and a regulating roller mounted thereon for rotation therewith near the grinding wheel. The roller will usually rotate around an axis substantially parallel with the axis of rotation of the grinding wheel, but said roller axis may be transverse of the wheel axis. Guide means on said fixture position a workpiece between the grinding wheel and regulating roller for rotation and grinding thereby. Drive means are connected to the grinding wheel and the shaft means for effecting rotation thereof.

10 Claims, 9 Drawing Figures Patented. April 24, 1973 3,729,300

3 Sheets-Sheet 1 Patented April 24, 1973 3 Sheets-Sheet 2 Patented April 24, 1973 3,729,300

3 Sheets-Sheet :3

CENTERLESS GRINDER FIELD OF THE INVENTION This invention relates in general to a machine capable of performing a centerless grinding operation and, more particularly, to a fixture capable of converting a conventional grinding machine having a grinding wheel into a centerless grinder.

BACKGROUND OF THE INVENTION The art of centerless grinding is well known and many machines have been developed for this purpose. However, there has been a long and recognized need for a fixture for quickly and easily converting a conventional surface grinder having a grinding wheel and workpiece supporting means into a centerless grinder, especially capable of handling extremely small workpieces and capable of performing an extremely accurate grinding operation.

Previous efforts to provide an extremely accurate centerless grinding machine capable of working on unusually small workpieces has been frustrated and limited by the accuracy of the shaft and bearing assembly supporting the regulating roller which cooperates with the grinding wheel to perform the centerless grinding operation. More specifically, even a very small amount of axial or radial movement of the roller supporting shaft can readily result in defective workpieces when close tolerances are required. Efforts to eliminate axial and radial play of the shaft relative to the frame structure supporting the shaft have resulted in excessively expensive structures or in a bent shaft which produces a different type of inaccuracy. That is, it has been extremely difficult, if not almost impossible, to provide a shaft which firmly engages the bearings in an axial direction, in order to prevent axial or radial movement ofthe shaft, without at the same time imposing a bending moment on the shaft. Thus, when the engaging surfaces of the nut and bearing adjacent thereto are tightly drawn together by the nut, the result has been a tendency to produce a bending moment in the shaft. More specifically, some form of external thread is required on existing shafts, for this purpose, to be engaged by a lock nut which imposes the thrust on the bearings. However, it has been impossible to furnish threads on the shaft, much less on the nut, by conventional inexpensive procedures, which threads have a central axis coaxial with the shaft.

In the course of studying the foregoing problems, it was discovered that axial and radial play could be eliminated without shaft deflection by providing an improved shaft and bearing construction wherein the shaft has two parts which are slightly axially spaced from each other in the assembled condition. These two parts are interconnected by screw means which extends substantially coaxially through one of the shaft parts and into the other shaft part. This screw means is of relatively small diameter, by comparison with the shaft diameter, so that a lack ofcoaxial relationship between its threads or the threads in the shaft means is incapable ofimposing a deflection of the shaft. Instead, the screw means will deflect. Moreover, the screw means does not directly engage the bearings, and the two parts of the shaft do not engage each other whereby a deflection of the shaft means might be caused.

The spindle of the grinding machine may be furnished with the above-described shaft and bearing assembly in order to eliminate axial movement thereof without deflection therein. However, if axial movement of the regulating roller is eliminated, then the adverse affects from the capability of the spindle to move slightly axially are nullified. That is, the regulating roller acting through the workpiece will tend to prevent axial movement of the grinding wheel. Moreover, it is common knowledge that the spindle of a grinding machine is usually supported by bearings arranged to minimize axial movement of the spindle shaft in order to adapt the grinding wheel for special grinding operations other than centerless grinding, which the grinding machine is capable of performing by means of the fixture of this invention.

Accordingly, a primary object of this invention is the provision of a fixture for converting into a centerless grinder a surface grinding machine having a rotatable grinding wheel and a workpiece support near said grinding wheel, whereby extremely small workpieces can be ground with extreme accuracy.

A further object of this invention is the provision ofa fixture, as aforesaid, capable of relatively inexpensive manufacture while maintaining extreme accuracy in performance and compactness in size so that said fixture can be quickly and easily mounted on the workpiece support ofa conventional grinding machine.

A further object of this invention is the provision of a centerless grinding machine having a regulating roller mounted upon a shaft and bearing assembly which is arranged and constructed so that axial and radial movement ofthe shaft is negligible, such being accomplished without producing undesirable deflections in the shaft and without the need for extremely accurate and costly machining operations on the parts of the fixture.

Other objects and purposes of this invention will become apparent to persons familiar with this type of equipment upon reading the following descriptive material and examining the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view ofa conventional surface grinding machine having a fixture constructed according to the present invention mounted thereon for converting same into a centerless grinding machine.

FIG. 2 is a perspective view of the fixture used for converting a surface grinder into a centerless grinder, the fixture being seen substantially from the rearward side thereof.

FIG. 3 is a rear elevational view of said fixture.

FIG. 4 is a top view of said fixture with the workpiece and pressure roller removed for illustrative purposes.

FIG. 5 is a sectional view taken along the line V-V in FIG. 3.

FIG. 6 is a fragmentary sectional view taken along the line VIVI in FIG. 4.

FIG. 7 is a fragmentary the line VllVIl in FIG. 3.

FIG. 8 schematically illustrates the coaction between the grinding wheel, the workpiece and the regulating roller when the grinding wheel is disposed directly above the regulating roller.

FIG. 9 is a schematic illustration of a further mode of operation wherein the grinding wheel is above, but axially offset from, the regulating roller.

sectional view taken along For convenience in description, the terms upper," lower, front, rear and words of similar import will have reference to the fixture of the invention and the grinding machine with which it isnormally associated as appearing in FIG. 2, which illustrates a rear view thereof. The terms inner, outer"and derivatives thereof will have reference to the geometric center of the fixture, the associated grinding machine and parts thereof.

SUMMARY OF THE INVENTION The objects and purposes of the invention, including those set forth above, have been met by providing a fixture which is utilized to convert a conventional surface grinding machine into a centerless grinding machine. The fixture includes a shaft and bearing means which supports a regulating roller beneath the grinding wheel so that the shaft of the fixture is parallel with and directly below the axis of the grinding machine spindle. The fixture includes guide means for positioning the workpiece in the space between the regulating roller and the grinding wheel. In this instance, the grinding wheel is driven by one prime mover and the roller sup porting shaft is driven by another prime mover, but a single prime mover means is contemplated.

DETAILED DESCRIPTION FIG. 1 illustrates therein a conventional surface grinding machine 11 provided with a frame 12 having a conventional horizontally extending spindle (not shown) rotatably supported thereon, which spindle is vertically movable and has a conventional grinding wheel 13 mounted thereon adjacent the forward end thereof. The frame 12 is also provided with either a single or double slide thereon, the machine 11 as illustrated being provided with a double or cross-slide arrangement which includes a bottom slide 16 slidably supported on the frame E2. The linear movement of the bottom slide 16 is controlled by a hand wheel 17. A top slide 18 is slidably supported on the bottom slide 16 and the linear movement thereof is controlled by a further hand wheel 19. The

slides

16 and 18 are mounted for slidable linear movement in directions transverse to one another and are additionally mounted for movement in directions which are parallel to and transverse to the rotational axis of the grinding wheel spindle. The above structure is conventional and thus further description thereof is not believed necessary.

According to the present invention, the surface grinding machine 11 is provided with a fixture 21 having a sine base 20 mounted on the upper table 18 in the space between the table 18 and the grinding wheel 13. Said fixture 2] is designed to convert the surface grinding machine so as to permit performance ofa centerless grinding operation on a cylindrical workpiece, such as workpiece W illustrated in FIG. 1.

The fixture 21, as illustrated in FIGS. 2 through 7, includes a pedestal 22 which is adapted to be mounted upon the sine base 20 by means of the two

cylindrical bars

23 and 23A. The bar 23 is pivotally connected to the sine base 20,- and the bar 23A is movable vertically relative to the sine base 20.

The pedestal 22 is provided with an upstanding portion 25 adjacent the front side thereof which rotatably supports a roller shaft means 24 (FIG. The shaft means 24 is disposed for rotation about a horizontal axis which is substantially'parallel with and vertically spaced below the rotational axis of the grinding wheel 13, but said shaft means can be pivoted with the pedestal 22 around the axis of bar 23.

The shaft means 24 is of two-piece construction and specifically includes a first shaft segment 27 having a regulating roller 26 nonrotatably secured upon one end thereof. The shaft segment 27 is rotatably supported by two pairs of

conventional antifriction bearings

28 and 29, which are separated by spacing

sleeves

40 and 40A and which are all disposed on one axial side of the regulating roller 26. The shaft segment 27 is also provided with a conventional retaining ring 31 secured thereto, which ring abuts the inner race of the antifriction bearing 28 for restricting axial movement of shaft segment 27 in the forward (leftward in FIG. 5) direction.

The shaft segment 27 has a tapered end (FIG. 5) of conventional configuration upon which an adapter 30 is rigidly secured by the nut 35 for mounting the roller 26 on said segment 27. The roller 26 may be fabricated from abrasive or nonabrasive materials, as desired. By furnishing a taper on shaft segment 27, the roller 26 can be quickly mounted upon the grinding wheel spindle for dressing of the roller at a much higher rotational speed, particularly where profile grinding is to be performed. This greatly reduces the time required to prepare the roller.

The shaft means 24 also includes a second shaft segment 32 which is coaxially aligned with and disposed adjacent the other end of the shaft segment 27. The adjacent surfaces of the

shaft segments

27 and 32 are slightly spaced from one another so as to define a small clearance space 33 therebetween, and a key or pin 36 extends between the

shaft segments

27 and 32 for holding said segments against relative rotation. A screw 34 is coaxial with and interconnects the

shaft segments

27 and 32, which screw results in total elimination of axial play of the shaft means 24 by causing the stop ring 31 to abut against the inner race of the antifriction bearing 28, while at the same time causing the shoulder 39 as formed on the shaft segment 32 to abut against the inner race of the antifriction bearing 29. This construction not only eliminates axial play of the roller shaft means 24, but also prevents deflection or distortion of the shaft means 24 due to the coaxial alignment of the connecting screw 34 with the shaft segments. Moreover, since the adjacent surfaces of the

segments

27 and 32 do not touch, it is unnecessary to accurately machine these surfaces in order to avoid a shaft deflection.

The shaft means 24 is indirectly driven by a conventional motor 41, which motor is drivingly connected to a conventional gear reducer 42 mounted on the frame 22. The output shaft of the gear reducer 42 has a driving pulley 40 (FIG. 4) secured thereto, which pulley is in engagement with a driving belt 38. The shaft segment 32 has a conventional pulley 37 secured thereto, which pulley is in engagement with and driven by the belt 38. The belt 38 and the pulleys associated therewith are preferably enclosed by a conventional shield or shroud 43.

The axis of the regulating roller 26, as disclosed in FIG. 8, is disposed under the grinding wheel 13 whereby a workpiece W can be positioned between and in engagement with the peripheries of the regulating roller 26 and grinding wheel 13 for permitting centerless grinding of the workpiece W. The axis of the workpiece W (FIGS. 8 and 9) may be slightly left or right (approximately one-eighth inch) of a line connecting the axes of the wheel 13 and roller 26 in order to achieve specific results.

To effect the centerless grinding of the workpiece W, the fixture 21 is provided with guide structure for maintaining. the workpiece W in the region between and in engagement with the regulating roller and the grinding wheel. Specifically a blade support 44 (FIGS. 2 and 3) is adjustably mounted upon the upstanding portion 25 of the pedestal 22 and a'pressure roller device 46 (FIG. 2) is adapted for coaction with the workpiece when the grinding wheel 13 and regulating roller 26 are axially offset, as appearing in FIGS. 2 and 5.

The blade support 44 (FIGS. 2 and 3) is vertically slidably mounted on the portion 25 of pedestal 22 by a pair of screws 48, which extend through vertically elongated slots 49 formed in the support 44. The support 44 is guided for vertical slidingmovement relative to the portion 25 by means of a vertically extending guide or slide pin 51 (FIG. 6).

The support 44 is provided with a rotatable adjustment member 52 threadedly engaged therewith, which adjustment member 52 has its lower end disposed in abutting engagement with an upwardly facing surface or shoulder 53 formed on the pedestal 22. The upper end of adjustment member 52 is disposed in a slot 54 formed in the support 44 for permitting the adjustment member 52 to be engaged by a conventional tool for selected rotation of the adjustment member 52, which in turn causes a selected vertical movement of the support 44 relative to the pedestal 22.

The blade support 44 has a substantially horizontal blade 56 mounted on the upper surface thereof. The blade 56 is adjustably secured to the support 44 by means of screws 57, which extend through elongated slots 58 formed in the blade 56 for permitting the blade to be adjusted linearly in a horizontal direction which is substantially transverse to the rotational axis of the regulating roller 26 for permitting the beveled edge 59 of the blade 56 to be moved into engagement with the periphery of the workpiece W. i

The pressure roller device 46 includes a pressure roller 61 adapted to be disposed in rolling engagement with the periphery of the workpiece W. The pressure roller 61 is rotatably supported adjacent one end of an arm 62, which arm is releasably but firmly secured to a block 63. The block 63 is nonrotatably connected to a pivot shaft 64 which is rotatably supported on the portion 25 of pedestal 22. A torsion spring 66 (FIG. 7) is disposed in surrounding relationship to one end of the pivot shaft 64 and has the opposite ends thereof anchored to the'pivot shaft 64 and the pedestal 22 for normally urging the pivot shaft 64 to rotate in a direction (clockwise in FIG. 3) which will cause the pressure roller 61 to be resiliently urged into engagement with the workpiece W.

A control handle 67, which is threaded and fixedly secured to the block 63, extends outwardly from the block for permitting the pivot shaft 64 and arm 62 to be selectively moved around the axis of shaft 64. The lower end of control handle 67 extends through an elongated slot 68 formed in the arm 62, which slot permits the arm 62 to be selectively moved relative to the block 63 so as to selectively vary the radial spacing of the pressure roller 61 from the axis of the pivot shaft 64. The arm 62 is releasably locked relative to the block 63 by means of a lock nut 69 provided on the control handle 67.

The pressure roller 61 (FIG. 4) may be canted slightly, such as 3, so that it automatically urges axial movement of the workpiece W toward (or away from) the positioning member 74.

The fixture 21 is also provided with a workpiece positioning device 71 (FIGS. 2 and 4), which device includes an arm 72 releasably connected to the pedestal 22 by means of a, screw 73, which screw permits the arm 72 to be adjusted angularly around the axis of the screw 73 for enabling the arm to be located in a selected angular position. An elongated positioning member 74 is supported on, and extends through an opening provided adjacent the free end of, the arm 72. Said positioning member is provided with a contact element 76 adjacent the rear end thereof, which element is adapted to engage the front axial end face of the workpiece W adjacent the center thereof. The elongated positioning member 74 is slidably supported by the arm 72 and is releasably secured to said arm in a selected position by means ofa locking screw 77.

The workpiece positioning device can also be mounted the front side of the blade support 44 by means of a rod (not shown) which is inserted into the opening 78 and to which the screw 73 is then attached. In this manner the device 71 is used to engage the other end of the workpiece.

The fixture 21 is also provided with a suitable nozzle member 79, which is connected to suitable lubricant or fluid supply conduits and has a discharge end positioned adjacent the workpiece for permitting the workpiece to be sprayed with a suitable lubricant and/or coolant.

When the fixture 21 is used in the manner disclosed in FIGS. 1 and 8, namely, with the wheel 13 and oller 26 in radially opposed positions, then an infeed device 81 is useful. Specifically, a bracket 82 is mounted upon the block 63 and adjustably supports an infeed finger 83. The workpiece W is engaged by the flat end of the finger 83 on the side thereof opposite the side engaged by the blade56.

OPERATION In utilization of the fixture 21 in cooperation with 'a conventional surface grinder 11 for permitting centerless grinding of cylindrical workpieces, the fixture 21 is mounted upon the sine base 20 which is secured upon the upper movable table 18 so that the regulating roller 26 may be disposed for rotation about a horizontal axis substantially parallel with and disposed below the rotational axis of the grinding wheel 13. However, the axis of the roller 26 may be tilted with the pedestal 22 around the axis of bar 23. The regulating roller 26 and grinding wheel 13 are spaced apart a sufficient distance to permit a suitable workpiece W to be engaged therebetween in the manner illustrated either in FIG. 1 or in FIG. 2. For purposes of illustration and explanation of the present invention, the workpiece W is shown as having two portions of different diameters, the large portion W1 (FIG. 5) being disposed directly on the regulating roller 26 and the other portion W2 projecting outwardly from the regulating roller. The portion W2 may have a diameter either less than orgreater than the portion W1.

Assuming first that it is desired to perform a centerless grinding operation on the workpiece portion W1, then the table 18 with the fixture 21 will be positioned so that the regulating roller 26 is disposed beneath the grinding wheel 13, whereupon the cylindrical workpiece portion Wl will be contacted on substantially diametrically opposite sides thereof by the grinding wheel 13 and the regulating roller 26, substantially as illustrated in FIG. 8. The blade 56 will be adjusted both vertically and horizontally so that the beveled edge 59 of the blade (FIG. 6) will be in tangential engagement with the periphery of the workpiece portion W1. Also, the infeed finger 83 (FIG. 8) will be adjusted into engagement with the opposite side of the workpiece. The workpiece portion W1 will thus be engaged at four points.

In this mode of operation, the pressure roller 61 and its arm 62 will normally be removed from the block 63 (FIG. 8) and replaced by infeed device 81. When in the position illustrated in FIG. 8, the grinding wheel 13 will be rotated in the direction illustrated by the arrow and will normally rotate at a much faster peripheral speed than the regulating roller so that the workpiece W will be continually rolled into engagement with the guide blade 56.

When it is desired to grind the projecting portion W2 of the workpiece, the table 18 and the fixture 21 mounted thereon will be moved frontwardly relative to the grinding wheel whereupon the grinding wheel and regulating roller will thus be axially offset from each other. When in this position, the workpiece portion W1 will be in contact with the regulating roller 26 and the blade 56, but the infeed finger 83 will be removed. The pressure roller arm 62 will be mounted in the operative position on block 63 (FIG. 2) so that the pressure roller 61 will be resiliently urged into rolling engagement with the'periphery of the workpiece portion W1. The pressure roller 61, blade 62 and regulating roller 26 thus provide a three-point support for the workpiece W, whereupon the grinding wheel 13 can then be moved downwardly into grinding engagement with the projecting portion W2 (FIG. 9) to perform a centerless grinding operation thereon, which operation will produce an accurately coaxial diameter.

The device constructed according to the present invention is thus operable for centerless grinding of members having portions disposed directly above or projecting laterally outwardly from the regulating roller, and is also adaptable for grinding members having sizes ranging from very small to relatively large diameters due to the manner in which the workpiece is disposed between the grinding wheel and the regulating roller.

Further, extremely accurate centerless grinding of the workpiece is possible with the fixture according to the present invention, even though the regulating roller. 26 is mounted adjacent one end of the shaft means 24, due to the manner in which the shaft is supported so as to be free of inherent axial play and lateral deflection, thereby permitting the centerless grinding of the workpiece with a high degree of precision.

Although particular preferred embodiments of the invention hasbeen disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of-the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a grinding machine having a grinding wheel having a first rotational axis and support means spaced from said grinding wheel, a fixture for converting said grinding machine to a centerless grinder, comprising:

base means mounted upon said support means;

shaft means having a second rotational axis, said shaft means being rotatably supported upon said base means and adapted to be positioned with said second axis substantially coplanar with said first axis;

bearing means mounted on said base means and rotatably supporting said shaft means;

said shaft means having separate, axially spaced, front and rear parts engaged by said bearing means, and threaded means coaxial with said shaft means and connecting said front and rear parts together;

a regulating roller mounted upon said shaft means near one end thereof for rotation therewith, said regulating roller being adapted for radial alignment with said grinding wheel;

drive means mounted upon said base means and connected to said shaft means near the other end thereof for rotating said shaft means; and

guide means mounted upon said base means for positioning a workpiece in engagement with said grinding wheel and said regulating roller, whereby said workpiece can be rotated and ground between said grinding wheel and said regulating roller.

2. A grinding machine according to claim 1 wherein said regulating roller is located in a position axially offset from said grinding wheel.

3. A grinding machine according to claim 1, wherein said bearing means comprises front and rear, axially spaced antifriction bearings, one of said bearings having inner race means and one of said shaft parts have a portion of enlarged diameter defining a shoulder engaged with said inner race means.

4. A grinding machine according to claim 1, wherein said bearing means comprises first and second, axially spaced antifriction bearings disposed adjacent and in surrounding relationship to the front and rear parts of the shaft means, respectively, said front and rear antifriction bearings being disposed on one axial side of said regulating roller, said front and rear parts of said shaft means having opposed end faces which are disposed adjacent but spaced from one another, and said front and rear parts further each having an abutment shoulder thereon fixedly secured thereto and disposed in abutting contact with the inner race of the front and rear bearings. respectively, for preventing axial play or movement of the shaft means.

5. A centerless grinding attachment for use with a grinder having a work table and a grinding wheel disposed above the work table and mounted for rotation about a first substantially horizontal rotational axis, comprising:

base means adapted to be supported on the work table;

shaft means having a second rotational axis, said shaft means being rotatably supported on said base means and adapted to be positioned so that said second rotational axis is substantially coplanar with and spaced downwardly from the first rotational axis of the grinding wheel;

a regulation roller secured to and rotatable with said shaft means adjacent one free end thereof, said regulating roller being adapted to be disposed below and substantially radially aligned with said grinding wheel;

bearing means coacting between said base means and said shaft means for rotatably supporting said shaft means on said base means, said bearing means being entirely disposed on one axial side of said regulating roller for supporting said regulating roller in a cantilever manner;

driving means connected to said regulating roller for driving same;

first guide means including a blade adjustably mounted on said base means and disposed substantially within a plane passing between said regulating roller and said grinding wheel for engagement with a cylindrical workpiece bearing against said regulating roller;

adjustment means on said first guide means coacting with said blade and with said base means for selectively effecting vertical and horizontal movement ofsaid blade relative to said regulating roller; and

second guide means including spring-urged roller means mounted on said base means and adapted for engagement with the cylindrical workpiece in a region thereof which is angularly displaced from the engagement between said blade and said workpiece.

6. An attachment according to claim 5, wherein said shaft means has a tapered portion near said one free end and said regulating roller has a tapered bore into which said tapered portion is snugly receivable, and screw means securing said roller on said shaft means.

7. An attachment according to claim 5, wherein said spring urged roller means is disposed for engagement with the cylindrical workpiece in a region thereof located above the axis of the workpiece.

8. An attachment according to claim 7, wherein said spring-urged roller means is canted at a slight angle relative to the regulating roller so that rotation of said spring-urged roller means while engaging said workpiece effects an axial urging thereof.

9. An attachment according to claim 7, wherein said shaft means includes first and second, axially aligned and axially spaced shaft segments having adjacent faces which are spaced from each other, said regulating roller being secured to and rotatable with said first shaft segment adjacent the free end thereof, said second shaft segment being connected to and driven by said driving means, and threaded fastener means coaxially aligned with and fixedly interconnecting said first and second shaft segments.

10. A centerless grinding attachment for use with a grinder having a work table and a grinding wheel disposed above the work table and mounted for rotation about a first substantially horizontal rotational axis, comprising:

base means adapted to be supported on the work table;

drive means mounted upon said base means and connected to said shaft means near the other end thereof for rotating said shaft means;

first guide means including a blade movably mounted on said base means and disposed for engagement with a cylindrical workpiece bearing against said regulating roller, said blade engaging said workpiece in a first region thereof located between the regions where said workpiece is contracted by said grinding wheel and said regulating roller;

said first guide means including adjustment means coacting with said blade for selectively effecting movement of said blade relative to said base means and relative to said regulating roller for permitting said blade to engage said cylindrical workpiece; and

second guide means mounted on said base means and engaging said cylindrical workpiece in a second region which is angularly displaced from all of said previously mentioned regions, said second guide means including roller means engaging said workpiece at said second region, means mounting said roller means for movement thereof relative to said base means in a substantially lateral direction relative to the axis of said roller means, and spring means normally resiliently urging said roller means into engagement with said workpiece.

Claims

1. In a grinding machine having a grinding wheel having a first rotational axis and support means spaced from said grinding wheel, a fixture for converting said grinding machine to a centerless grinder, comprising: base means mounted upon said support means; shaft means having a second rotational axis, said shaft means being rotatably supported upon said base means and adapted to be positioned with said second axis substantially coplanar with said first axis; bearing means mounted on said base means and rotatably supporting said shaft means; said shaft means having separate, axially spaced, front and rear parts engaged by said bearing means, and threaded means coaxial with said shaft means and connecting said front and rear parts together; a regulating roller mounted upon said shaft means near one end thereof for rotation therewith, said regulating roller being adapted for radial alignment with said grinding wheel; drive means mounted upon said base means and connected to said shaft means near the other end thereof for rotating said shaft means; and guide means mounted upon said base means for positioning a workpiece in engagement with said grinding wheel and said regulating roller, whereby said workpiece can be rotated and ground between said grinding wheel and said regulating roller.

4. A grinding machine according to claim 1, wherein said bearing means comprises first and second, axially spaced antifriction bearings disposed adjacent and in surrounding relationship to the front and rear parts of the shaft means, respectively, said front and rear antifriction bearings being disposed on one axial side of said regulating roller, said front and rear parts of said shaft having opposed end faces which are disposed adjacent but spaced from one another, and said front and rear parts further each having an abutment shoulder thereon fixedly secured thereto and disposed in abutting contact with the inner race of the front and rear bearings, respectively, for preventing axial play or movement of the shaft means.

5. A centerless grinding attachment for use with a grinder having a work table and a grinding wheel disposed above the work table and mounted for rotation about a first substantially horizontal rotational axis, comprising: base means adapted to be supported on the work table; shaft means having a second rotational axis, said shaft means being rotatably supported on said base means and adapted to be positioned so that said second rotational axis is substantially coplanar with and spaced downwardly from the first rotational axis of the grinding wheel; a regulation roller secured to and rotatable with said shaft means aDjacent one free end thereof, said regulating roller being adapted to be disposed below and substantially radially aligned with said grinding wheel; bearing means coacting between said base means and said shaft means for rotatably supporting said shaft means on said base means, said bearing means being entirely disposed on one axial side of said regulating roller for supporting said regulating roller in a cantilever manner; driving means connected to said regulating roller for driving same; first guide means including a blade adjustably mounted on said base means and disposed substantially within a plane passing between said regulating roller and said grinding wheel for engagement with a cylindrical workpiece bearing against said regulating roller; adjustment means on said first guide means coacting with said blade and with said base means for selectively effecting vertical and horizontal movement of said blade relative to said regulating roller; and second guide means including spring-urged roller means mounted on said base means and adapted for engagement with the cylindrical workpiece in a region thereof which is angularly displaced from the engagement between said blade and said workpiece.

10. A centerless grinding attachment for use with a grinder having a work table and a grinding wheel disposed above the work table and mounted for rotation about a first substantially horizontal rotational axis, comprising: base means adapted to be supported on the work table; shaft means having a second rotational axis, said shaft means being rotatably supported upon said base means and adapted to be positioned with said second axis substantially coplanar with said first axis; a regulating roller mounted upon said shaft means near one end thereof for rotation therewith, said regulating roller being adapted for radial alignment with said grinding wheel; drive means mounted upon said base means and connected to said shaft means near the other end thereof for rotating said shaft means; first guide means including a blade movably mounted on said base means and disposed for engagement with a cylindrical workpiece bearing against said regulating roller, said blade engaging said workpiece in a first region thereof located between the regions where said workpiece is contracted by said grinding wheel and said regulating roller; said first guide means including adjustment means coacting with said blade for selectively effecting movement of said blade relative to said base means and relative to said regulating roller for permitting said blade to engage said cylindrical workpiece; and second guide means mounted on said base means and engaging said cylindrical workpiece in a second region which is angularly displaced from all of said pReviously mentioned regions, said second guide means including roller means engaging said workpiece at said second region, means mounting said roller means for movement thereof relative to said base means in a substantially lateral direction relative to the axis of said roller means, and spring means normally resiliently urging said roller means into engagement with said workpiece.