US3334445A

US3334445A - Grinding machine

Info

Publication number: US3334445A
Application number: US406433A
Authority: US
Inventors: Walter F Green
Original assignee: Timken Roller Bearing Co
Current assignee: Timken Co
Priority date: 1964-10-26
Filing date: 1964-10-26
Publication date: 1967-08-08
Anticipated expiration: 1984-08-08
Also published as: GB1048336A; BR6571131D0

Description

Aug. 8, 196? w. F. GREEN GRINDING MACHINE 3 Sheets-Sheet 1 Filed Oct. 26, 1964 Aug. 8,1967 w. F. GREEN GRINDING MACHINE 5 Sheets-Sheet 2 Filed Oct. 26, 1964 m2 I mm c No; M W IE F m% H m Z W I w. F. GREEN 3,334,445 GRINDING MACHINE 5 Sheets-Sheet 5 Aug. 8, 1967 Filed 001;. 26, 1964 United States Patent 3,334,445 GRINDING MACHINE Walter F. Green, Canton, Ohio, assignor to The Timken Roller Bearing Company, Canton, Ohio, a corporation of Ohio Filed Oct. 26, 1964, Ser. No. 406,433 Claims. (Cl. 51-103) The present invention relates to a grinding machine, and particularly relates to the grinding of tapered rollers which are long as compared to their diameter and which have spherical or conical ends.

The present invention is an improvement on the grinder shown in Patent No. 2,478,607. The machine of Patent No. 2,478,607 has been extremely valuable in the antifriction bearing industry in the grinding of the raceways of the inner races (cones) and has resulted in these raceways being ground to much closer limits than have been economically possible for the rollers themselves. Conventionally tapered rollers are ground by either through feed or plunge cut centerless grinding machines. Limitations of these machines include lobing, slippage between the regulating wheel and the tapered roller, and runout errors of the regulating wheel shaft and the bearings. Heretofore, all efforts to grind tapered rollers by the microcentric principle of Patent No. 2,478,607 have ended in failure.

The microcentric principle makes use of a flat rotating drive plate against which the flat surface of the raceway is urged, by any one of several methods (i.e., pressure rollers, magnetic driver or pressure ring). Thus, the raceway being externally ground takes its lateral and angular position from the driver plate. The shoes, supporting the surface being ground, only need to generate the true circular cross section at one point along the length of the raceway and then all other sections along the length of the race also become round with the axis of rotation square with the driver surface.

An attempt to apply the same principle to tapered rollers whose length may be from one to four times their maximum diameter and whose ends are special or conical has not resulted in accurate work. If the grinding pressure is greater at one end or the other, the roller merely skews or rocks and the end shifts in its spherical or conical seat. Thus a circular cross section is generated only at the cross section supported in the shoes. All other sections are out of control and are oval shaped or lobed.

Previous attempts to apply similar but modified arrangements have incorporated two pairs of shoes placed laterally along the length of the roller with the grinding wheel fed radially toward the work. But since the diameter of the work at each set of shoes is reducing, swivel shoes (as indicated on FIG. 10 of Patent No. 2,478,607) are needed to maintain reasonable area of contact with the roller, but now with four swivelling shoes all contacting the frustrum of the roller, the grinding and positioning of the four shoes to accurately contact an on taper roller becomes impractical, if not impossible. Contact with only three of the four shoes with even one ten-thousandth clearance with the fourth will produce inaccurate geometry.

Accordingly, it is a principal object of the present invention to provide an apparatus of grinding tapered rollers having spherical or conical ends and whose length is from one to four times the maximum diameter to extremely close tolerances.

Another principal object of the present invention is to provide a roller grinding device utilizing axial feed through a rotating driver which has limited universal movement with respect to the feed, and utilizing fixed shoes and grinding wheel to grind the rollers to extremely close tolerance limits.

3,334,445 Patented Aug. 8, 1967 Another object of the present invention is to provide a grinder utilizing an axial feed through a rotating driver which is eccentrically positioned with respect to the tapered roller so as to provide seating pressure for the roller against prepositioned shoes which, in conjunction with a prepositioned grinder, accurately determines the final size of the roller.

Still another object of the present invention is to provide a roller structure wherein rollers can be finished ground in the grinder and removed therefrom without scoring or scratching the polished roller surface.

These and other objects and advantages will become apparent hereinafter.

In the drawings wherein like numbers refer to like parts wherever they occur:

FIG. 1 is a fragmentary foreshortened plan view of the present invention;

FIG. 2 is a fragmentary elevational view partly in section of the invention;

FIG. 3 is a fragmentary diagrammatic view of an indicating device of the invention;

FIG. 4 is a sectional view of a driver mechanism;

FIG. 5 is an end elevational view of the driver shown in FIG. 4.

FIG. 6 is a fragmentary view partly in section of a back-up mechanism; and

FIG. 7 is an enlarged fragmentary view partly in section of the grinding mechanism.

The present invention comprises a tapered roller grinding machine including fixed shoes to determine the final diameters at the ends of the rollers, a grinding wheel, and a rotating driver which is free to wobble with respect to the end of the roller and which is rotatably driven and axially fed to move the roller through the grinding machine. The present invention further comprises the method and apparatus hereinafter described and claimed.

FIGS. 1 and 2 show a roller grinding machine 10 which comprises a stand 11 upon which is mounted a base 12 and a grinding wheel 13. The base 12 mounts four shoes 14 which are provided with carbide inserts 15 of predetermined inner diameters and which are adjustable, through the screw and slot mechanisms 16, toward and away from the center line of the object to be ground (illustrated as a tapered roller 17). The roller 17 is positioned in the carbide inserts 15 which are mounted in the shoes 14 and positioned in pairs at the large and small ends of the roller 17.

The shoes 14 can either be solid, integral with the base 12, or, as shown, adjustable so that the carbide inserts 15 may be reground.

The sets of shoe inserts 15 are ground to predetermined diameters which correspond to the final. diameter of the small and large ends of the roller 17. These diameters are constant and determine the size of the final ground roller 17 The grinding wheel 13 is positioned on an angle with respect to the centerline of the roller 17 corresponding to the taper of the roller 17.

An unloading mechanism comprising an arm 18 positioned beneath the roller 17 between the shoes 14 and pivotally attached at its other end 19 also is provided on the base 12. A handle 20 is used to pivot the unloading arm 18 toward and away from the shoes 14. Thus the ground roller 17 can be laterally removed from the shoes 14 without sliding the roller along the shoes 14 and possibly scoring or scratching the polished roller 17.

The drive mechanism for the roller 17 is generally indicated by the number 21 and is mounted on a movable slide 22 which is axially moved by a hand wheel 23 through a suitable screw mechanism 24. Rotation of the hand wheel 23 moves the drive mechanism 21 toward and away from the grinding wheel 13. The drive mechanism 21 comprises a spindle adapter or drive member 25,

having spaced arms 25a extending outwardly from the centerline thereof, and adapted to be connected to a drive pulley shaft driven by a chain and sprocket drive 26 from the output shaft of a drive motor 27, a coupling ring 28 connected to the spindle adapter 25 at the periphery of the arms 25a and to a driver 29 at the periphery of outwardly extending arms 2% by screws 31). The points of connection of the ring 215 to the arms 25a and 2% are spaced around the ring 28 and are separate from each other, The coupling ring 28 is flexible enough to allow some pivoting movement between the adapter 25 and the driver 29, and also is stiff enough to transmit the rotary motion of the spindle adapter 25 to the driver 29.

The spindle adapter 25 also is connected to the driver 29 through a steel ball 31 at the centerline of the adapter 25 and the driver 29. This type of universal connection allows the driver 29 to wobble with respect to the centerline of the adapter 25, and to compensate for any 011- squareness of the spherical or conical large end of the roller 17. A nose 32 is positioned on the leading edge of the driver 29 and has teeth 33 on its leading edge. The nose 32 is of a plastic, such as nylon, and connects to the large end of the roller 17 so that the roller 17 is rotated as the driver 29 is rotated Furthermore, since the driver 29 is axially movable toward and away from the grinding wheel 13 by means of the hand wheel 23, it thus advances the roller 29 along the grinding area between the shoes 14 and the grinding wheel 23.

At the small end of the roller 17 is a back-up device 34 which includes a fixed outer housing 35 mounted on the base 12 and a slidable inner housing 36 which is keyed to the outer housing at 37 and is connected to an air cylinder 38 which is pressurized to act against the small end of the roller 17 with a constant pressure through a connecting hub 39. The hub 39 is rotatable with respect to the inner housing 36, through a series of antifriction tapered roller bearings 40. The centerline of the back-up hub 39 is aligned with the centerline of the driver 29, and these are eccentric with respect to the cenerline of the roller 17 as may be seen clearly in FIG. 7. The center line of the driver 2) and the back-up hub 39 (indicated by the intersection of the lines A in FIG. 7) is above and to the right of the centerline of the roller 17 (indicated by the intersection of the lines B in FIG. 7) to urge the roller 17 downwardly and against the shoes 14.

Operation In operation, a finish ground roller is inserted into the shoes 14 and positioned to fit snugly. An air orifice 41 mounted in a bracket (shown in FIG. 3) operates a control dial 42 which then is adjusted until the needle in the dial is at the zero position. The orifice 41, in effect, measures a constant diameter over the small end shoes 14, and once the orifice 41 is set, the position of the roller 17 snugly against the shoes 14 is maintained by keeping the needle on the dial 42 at zero while grinding. As the grinding wheel 13 removes stock from the outside diameter of the roller 17, the roller 17 can be advanced along the shoes 14 and the wheel 13 by means of the hand wheel 23 to maintain the roller diameter measured by the orifice 41.

In other words, by maintaining the roller 17 tightly against the fixed shoes 14 (which are located near the small and large ends of the roller 17 and have fixed diameters) the roller 17 is ground to a predetermined diameter at those circular cross sections adjacent to the shoes 14. As the grinding wheel 13 extends past the shoes 14 and covers the entire length of the roller 17, the roller 17 is precision ground over its entire length on a taper corresponding to the angular adjustment of the wheel 13 with the centerline of the roller 17 T determine the amount of stock removed from the roller 17, the amount of advance of the roller 17 is measured by an air orifice 13. The amount of stock to be removed from the roller 17 is predetermined, and a gage contact is set with the roller 17 in grinding position to indicate stock removal on the gage dial 4d.

To start the grinding, the grinding wheel 13 is advanced toward the roller 17 (which is connected to the driver nose 32 and driven by the motor 27 until a light spark is obtained. The wheel 13 then is locked into position, and the hand wheel 23 is rotated to advance the slide 22 and the rotating roller 17 through the grinding area. As the roller 17 is advanced, the diameters at the fixed shoes 14 are maintained constant.

When the roller 17 has reached finished size (determined by the reading on the size dial 44) the grinding wheel 13 is retracted and the roller 17 continues spinning until the small end back-up 34 is removed from contact with the roller 17. The ejection arm 18, then is actuated to remove the roller 17 laterally from the grinding area, so that the roller 17 does not have to be slid along the shoes 14, which may cause scoring or scratching of the roller 17.

Using the present apparatus and method, three of the conventional steps in grinding rollers are eliminated, as well as producing a roller to much closer tolerances with much less waste than heretofore possible.

This invention is intended to cover all changes and modifications of the examples of the invention herein chosen for purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention.

What is claimed is:

1. A grinding machine for tapered workpieces comprising a base, lengthwise spaced pairs of shoes defining a grinding area, said pairs of shoes having workpiece contact contour of different predetermined diameters corresponding to the final diameters of the ends of the workpieces, a grinding wheel positioned across the grinding area from the shoes at an angle corresponding to the finished taper of the workpieces, and drive mechanism for rotating and axially moving in the grinding area the object to be ground including a rotatable and axially movable drive member having means for being attached to one end of the object to be ground.

2. The structure of claim 1 wherein the drive mechanism includes a rotating drive means, means for imparting the rotation of the drive means to the drive member, means for axially moving the drive member, a second member for engaging the object to be ground, a flexible ring connected to the drive member and to the second member at spaced separate points on their peripheries, and a universal connecting means connecting the drive member to the second member on their centerlines.

3. The structure of claim 1 including a back-up structure for engaging the second end of the object to be ground, said back-up structure including a rotatable member and means for urging the rotatable member against the other end of the object to be ground.

4-. The structure of claim 3 wherein the centerline of the drive member and the rotatable member of the backup structure is offset from the centerline of the object to be ground to urge the object to be ground against the shoes 5. The structure of claim 1 wherein the shoes have carbide inserts for engaging the object to be ground.

6. The structure of claim 1 wherein the shoes are adjustable toward and away from the object to be ground.

7. The structure of claim 1 including unloading mechanism for removing the object to be ground from the grinder after it is ground, said mechanism including an arm having one end underlying the object during grinding and pivoted at its other end so that the ground object is lifted from the shoes when the arm is moved about the pivot.

8. A grinding machine for a tapered workpiece having a spherical or conical end and relatively long in relation to the diameter comprising a base, two longitudinally spaced pairs of shoes defining a grinding area through which objects to be ground are moved, said shoes having carbide inserts with contact contour of predetermined diameter positioned adjacent to each end of the grinding area, a grindnig wheel positioned along the grinding area across from the shoes in angular relation to the centerline of the objects to be ground, drive mechanism for rotating and axially moving the object to be ground including rotating drive means, means for imparting rotation from the drive means to a drive spindle having a socket at its centerline, means for axially moving the drive spindle while it is rotating, workpiece engaging means having a socket at its centerline, outwardly extending arms on the workpiece engaging means, a flexible ring positioned between the drive spindle and the work piece engaging means, means connecting the flexible ring to the ends of the arms at spaced separate locations around the ring, and a ball positioned in said sockets,

said ball and socket and ring engagement providing limited universal movement between the drive spindle and the workpiece engaging means, and a back-up structure for engaging the second end of the object to be ground, said back-up structure including a rotatable member and means for urging the rotatable member against the said second end of the object to be ground, the centerline of the drive spindle and the rotatable member of the backup structure being offset from the centerline of the object to be ground to urge the object to be ground against the shoes.

9. The structure of claim {5 wherein the shoes are adjustable toward and away from the object to be ground.

10. The structure of claim 8 including unloading mechanism for removing the object to be ground from the grinding machine after it is ground, said mechanism including an arm having one end underlying the object during grinding and pivoted at its other end so that the ground object is lifted from the shoes when the arm is moved about the pivot.

References Cited UNITED STATES PATENTS 1,096,189 5/1914 Norton 51-289 1,342,375 6/1920 Dunham W 51-103 1,611,135 12/1926 Sanford 51103 X 1,676,620 7/1928 Norton 51103 1,722,386 7/1929 Norton 51-103 2,059,895 11/1936 Norton et al. M 51103 2,478,607 8/1949 Theler et al. 51--103 2,772,526 12/1956 Boyd 51236 LESTER M. SWINGLE, Primary Examiner.

Claims

1. A GRINDING MACHINE FOR TAPERED WORKPIECES COMPRISING A BASE, LENGTHWISE SPACED PAIRS OF SHOES DEFINING A GRINDING AREA, SAID PAIRS OF SHOES HAVING WORKPIECE CONTACT CONTPUR OF DIFFERENT PREDETERMINED DIAMETERS CORRESPONDING TO THE FINAL DIAMETERS OF THE ENDS OF THE WORK PIECES, A GRINDING WHEEL POSITIONED ACROSS THE GRINDING AREA FROM THE SHOES AT AN ANGLE CORRESPONDING TO THE FINISHED TAPERED OF THE WORKPIECES, AND DRIVE MECHANISM FOR ROTATING AND AXIALLY MOVING IN THE GRINDING AREA THE OBJECT TO BE GROUND INCLUDING A ROTATABLE AND AXIALLY MOVABLE DRIVE MEMBER HAVING MEANS FOR BEING ATTACHED TO ONE END OF THE OBJECT TO BE GROUND.