US2494555A - Centerless grinding machine - Google Patents

Description

Jan, 17, 1956 G. E. HIEBER CENTERLESS GRINDING MACHINE 2 Shee'ts-Sheet 1 Filed Dec. 3, 1946 84 02 3 337 ..m.l T.

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CENTERLESS GRINDING MACHINE Filed Dec. 3, 1946 2 Sheets-Sheet 2 GEORGE E. HIEBER the work piece.

Patented .ian. l7, 1 95 ICE CENTERLESS GRINDING MACHINE George E. Hieber, Waynesboro, Pa., assignor to Landis Machine Company, Waynesboro, Pa., a corporation of Pennsylvania Application December 3, 1946, Serial N 0. 713,795

18 Claims.

This invention relates to centerless grindin machines and in particular to grinding machines of the centerless type in which the regulating or control wheel performs certain feeding and ejecting functions in addition to controlling the rotation of the work piece in the grinding throat formed between the opposed peripheral surfaces of the control and grinding wheels.

The invention is an improvement over the manually operable type of machine shown and described in the copending application of Arthur Scrivener, Serial No. 556,426, filed September 29, 1944, now Patent No. 2,427,024, issued September 9, 1947.

While the Scrivener invention is quite efiicient for many operations, the removal of a large amount of metal from the work piece is made difficult by reason of the tendency of the grinding wheel to. impart a high rotational speed to This is transmitted to the control wheel, creating a strong torque which it is dificult for the operator to control by means of the operating handle. Consequently, the use of the Scrivener invention: is restricted in respect to the amount of metal to be removed from the work piece.

Accordingly it is an object of this invention to provide means for .controllably absorbing the reactionary torqueforce transmitted from the grinding wheel to the control wheel during the grinding operation.

It is another object of the present invention to provide means for controllably absorbing the torque force transmitted to an oscillating control wheel during the grinding operation, while nullifying the controlling eiiect of said means during the return stroke of the control wheel.

A further object of the invention is to employ fluid means to facilitate the manual operation of an oscillating control wheel with uniform vide mechanism as above characterized comprising an extremelycompact-arrangement of structurally simple elements which will be highly efficient in functional operation and which will not retard the operational speed of the machine nor interefere, by virtue of its location, with the functions of other parts of the machine.

Further objects and advantages will be apparent from a consideration of the following description and the accompanying drawings which illustrate a preferred embodiment of the I invention.

In the drawings, wherein like reference characters designate corresponding parts throughout the several views:

Figure 1 is a partial front elevation of the Serial No. 571,518, filed January 5, 1945, now Patent No. 2,417,413, issued March 18, 1947. A work rest blade 24 is supported in the grinding throat by the mechanism 22. A motor driven grinding wheel 26 having thread grinding ribs on its peripheral surface is supported by the base of the machine (not shown) adjacent to work rest blade 24 to effect abrading action upon a work piece W placed on an inclined top surface 28 thereof.

Any conventional means may be used to adjust the main slide 2|] together with the work rest mechanism 22 in a direction perpendicular to the axis of the grinding wheel 26 in order to position the work rest blade 24 at the proper distance from said grinding wheel. An auxiliary slide 30 is mounted on main slide 20 and sup- 7 ports a housing 32. A control wheel 34 is supported, by means later to be described, in the housing 32. Any conventional means may be employed to adjust slide 30, housing 32 and control wheel 34 in a direction perpendicular to the axis of grinding wheel 26 in order to provide a grinding throat of the proper width between grinding wheel 26 and control wheel 34.

A control wheel spindle 35 is mounted at each end in the usual manner on suitable bearing 31 in a bore 36 in housing 32. A cap member 38, secured by screws 40 to housing 32 at the forward end of bore '36 and surrounding spindle 35, is employed to retain said spindle and its bearings in bore 36. Forwardly of cap member 38,

spindle 35 is formed with a reduced diameter tapered portion 42. Mounted upon portion 42,

'85 a wheel supporting member 44 is restrained The mechanism 22 may be similar to that shown and described inthe copending applicationof C. W. Hopkins, i

against axial movement by a cap screw 46 threadedly engaged in the forward extremity of spindle portion 42 and having a flange 48 which engages the bottom of a counterbore 58 in the forward end of the Wheel supporting member 44.

At its rear end, member 44 is formed with a diametrically enlarged portion 52 provided with an external annular flange 54. The part 52 of the member 44 is fltted within one end of the central circular opening 56 of the control wheel 34 with the flange 54 in abutting contact against the adjacent side face of the wheel. An annular member 58 is telescopically fitted over the other end of the member 44 and within the opposite end of the opening 55 of the control wheel, said member having the flange 60 for abutting contaQ a against the front face of said wheel. This member 58 is connected with the part 52 of member 44 by means of the cap screws 62 having threaded connection with said part 52 and whereby the memb 4.4. and 531 are rigidly o nec against relative rotation and with their flanges 54 and 60, respectively, in tight clamping contact with h oppos te ide fac of c n o wh 3 Forwardly adjacent flange 48 of screw 45, a bushing 64 is secured in bore 50 of member 44 by it I n P 82 in exact alignment with the axis of wheel spindle 35. A short shaft 84 is mounted in bore 82 on bushing 86 and needle bearing 88. The rearward end of bore 82 is closed by the sealing member 90. To the rearward end of shaft 84 is secured a radially extending clutch dog 92 for selectively engaging one of the slots 68 in the forward, face of member 44, thus providing a driving connection between shaft84 and control wheel 34. It will be apparent that the reason for such selectivity is to bring any one of the pockets l6,

E8 or others of control wheel 34 into proper workreceiving position relative to work rest 24.

The forward end ofshaft 84 is provided with a transverse rectangular groove 94 in which is seated one end of ancperating lever 96, said lever being secured to shaft 84 by means of screws 98.

The forward surfaceof cover member 10 is provided with an arcuate T-slot I00 having its center of curvature coincidental with the axis of shaft 84. A pair of T-shapedblochs I02 are seated in T-slot [09 and are provided with tapped holes for threaded engagement-by cap screws Hi4 which retain stop lugs I06 against the forward surface of cover member [0. Thus it is evident that stop lugs [05 may be secured in any desired spaced mm WWII the ends or T-sloi connection between control wheel 34 and operat ing lever 96 exists. i

As shown in Figure 2, shaft 84 is formed as a spur pinion I34 for part of its length. -As shown in Figure 3, a cylindrical member I36 is mounted in a bore I38 which in the present case, passes diagonally through the cover member 10. Member I36 has an intermediate semi-cylindrical section provided along its fiat side with rack teeth, I40 which are in constant mesh with the pinion. I34. The upper end of bore I38 is closed by awelch plug I42 while the lower end is closed by a gasket I44 and cover plate I46 which are secured to cover member by means of screws I48. The lower end of member I36 is surrounded by a series of hydraulic packing elements I50 of leather or other suitable material. This packing I50 is retained in place by a washer I 52 and locknuts I54 which are threadedly engaged on the extremity of member I36. Thus, bore I38 and member 536 comprise a hydraulic cylinder-andpiston combination. It will be seen in Figure 3 that cover plate I46 which closes one end of the cylinder I 38, is provided with a recess I56 into which lock nuts I54 extend at the extreme downward travel of piston I36. The interior of cover member 10 isvoided as seen in Figures 2 and 3 to form a large oil reservoir i58. Near the top of reservoir I58 a passage IE8 is provided, connecting said reservoir I58 with the cylinder I38. The bottom end of cylinder I 38 is connected by a channel I62 to a passage I64 which is provided with a seat for a valve I66. Above the valve I66, passage I64 communicates with the reservoir I 58. Valve I66 is provided with a downwardly extending cylindrical portion I68 which is utilized to retain one end of a coil spring I10, the opposite end of which is held in position by a pin I12, frictionally mounted in cover plate I46. Spring I10, being held in compression between cover plate I46 and valve I66, serves to urge the valve against its seat and thereby fluid is prevented from leaving the lower end of cylinder I38 and passing through passage I64 to reservoir I58. On the other hand, a drop, in fluid pressure in the lower end of cylinder I38 will result in valve I66 being drawn downwardly away from its seat, compressing spring I10 and permitting fluid from reservoir I58 to pass through passage I64 and channel I62 into cylinder I38.

Another cylindrical opening I14 is formed in. the wall of cover member 10 and communicates with passage I64 at the outer side of valve I66. A metering valve seat member I 16, having a portion I18 of its interior threaded, is mounted in opening I 14, being retained therein by the member I88 which is threadedly engaged in the end of opening I14. Suitable packing I82 is inserted between members I16 and I80 to prevent the escape of fluid from cover 10.

A valve stem I84 is threadedly engaged with portion I18 of valve seat member I16 and has a portion I86 of reduced diameter extending coaxially within said member toward cylinder I38. A valve orifice I88 is formed at the inner end of seat member I14, while the valve stem portion. I86 terminates in a tapered needle point. This tapered portion I90 cooperates with valve oriflce= I88 to form a metered passage for the hydraulic fluid, the effective area of said passage being selectively variable by advancing or withdrawing valve stem I84. This is done by manual rotation. of a knob I92 afiixed to the protruding end of stem I84. The threaded engagement between ner, the amount of fluid leaving the lower end of cylinder I38 and hence the hydraulic resistance to downward movement of member I36 may be controlled.

A radial opening I94 is formed in the wall of seat member I16 and provides a connection between the interior of member I16 and an annular groove I96 formed in the circumference of seat member I16. Another opening I98 is provided in the wall of reservoir I58 to connect said reservoir to groove I96 and thence to the bore of seat member I14 and through valve orifice I88 and I passage I64 to cylinder I38. Fluid is introduced into reservoir I58 and replenished from time to time as necessary through a conventional oiler 200 mounted in the top wall of reservoir I58. A

drainage opening, normally closed by threadedplug 202, is in communication with the groove I96 in member I16.

Operation At the beginning of the cycle of operation necessary to grind threads on a Word piece by means of the machine above described, the pocket 16 in control wheel 34 is positioned with its lower side below the top of work rest blade 24 and operating lever 96 is in its extreme counter-clockwise position, in contact with the upper stop lug I06. A work blank to be operated upon is placed in pocket 16 and manual rotation of operating lever 96 in a clockwise direction is begun. It

will be apparent that rotation of operating lever.

sage I64 because of check valve I66, the fluid forced from cylinder I38 must proceed through the metering valve orifice I88, opening I94, groove I96 and opening I98 into reservoir I58. As before stated, the rate of this flow and therefore the speed of descent of piston I36 can be,

precisely regulated by the advance or withdrawal of metering valve stem I84.

Rotation of control wheel 34 in a clockwise direction causes the work piece to roll upwardly upon the inclined surface 28 of work rest blade 24 and to be brought into grinding ribs on grinding wheel 26. As peripheral section of control wheel 34 is brought into contact with the work piece a strong torque is transmitted from the power driven grinding wheel through the work piece to the control wheel 34. The value of such force is dependent upon the amount of metal sought to be removed from the work piece. In case a finished thread is being ground from a solid cylindrical work blank, this force is of such severity that, without the use of the control mechanism above described,

manual rotation of the control wheel is impossible and operating lever 96 is rapidly and violently rotated to its extreme clockwise position, sometimes with force sufiicient to damage many of the machine elements.

However, since shaft 84 and pinion I34 must operate against the hydraulic resistance to move-;-;

contact with the thread I gamers:

merit ofpistonl ss', the force transmitted from grinding'wheel 2W through the work piece tocontrol wheel 3 is absorbed by the hydraulic pressure in the lower end of cyi ind'er I38, so: that the operating lever 56- may' be manually rotated with case. In this manner, it will be apparentv that the effect of any driving torque from the grinding wheel upon the "control wheel; having. a value exceeding that required tomanually osciliate the control wheel will be substantially nul-- li fiedi It should benoted that, during the grind.- ing operation, a vacuum the-upper end. of cyl:- inder E38 is prevented by the: opening i265 which permits fluidtopass freely from reservoir 58 to cylinder i 38. 1

When the rotation ct control wheel: 34 brings pocket 181 adjacent the top. of' work rest blade 24, the operating lever 96*. strikes the. lower stop lug Hi5 and the: work piece. dropsv into" pocket i=8. Operating: lever- 96 isrthen rotated counter-clockwise to return pocket 16 to loading. position. During this portion of theworkcycle, the operating level 96 may be moved with the same facility as if the-hydraulic mechanism were not used. This is the resul-t'of the partialvacuum created in the lower end of cylinder 38 by the upward movement of piston [36. As before described, fluid isthus freely drawn from reservoir 358 through the check valve and into the lower end of cylinder E38, equalizing the pressures at oppositeend's of piston I38 so that control wheel 34 is: easily returned to: its starting position.

From the above it will be seen that by means of a mechanically simple andinexpensive addition to the manually operable machine of the Scrivener patent previously mentioned, the strong torque force which would otherwise be transmitted from the grinding wheel to the control wheel may be effectively neutralized or nullined so that the machine may be safely operated under high working pressures without danger of injury to the operator or damage to the machine parts. Also the invention provides a machine of this type which may be operated with great ease and facility to obtain maximum production of accurately iii-fished work pieces;

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes WhiC'h'COIllE within the meaning and range of equivalency of the claims 55 are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a. centerless grinding machine, a power driven grinding wheel, a control wheel in periph- 6i? erally opposed relation to said grinding wheel to form a work grinding throat, drive means for said. control wheel and additional means for substantially nullifying the transmission of driving. torque exceeding a predetermined value; from' the grinding wheel through the work piece to said" control wheel.

2. A centerless grinding machine as defined in claim 1, wherein said additional means comprises a hydraulic torque neutralizer operatively con- 7 y neot'ed with the control wheel.

3. A centerless grinding machine as defined in"- claim 1, wherein said additional means comprises a hydraulic torque neutralizer operatively conmeans for variably regulating the effective re-- sponse of said neutralizer to torque forces of different' values.

4 In acen-terless grinding machine, a power driven grinding wheel, an oscillatable control wheel in peripherally opposedrelation to said grinding wheel toform a grinding throat, means for manually operating said control wheel, and means operatively connected with said last named means, responsive only to: oscillation of the control' wheel in grinding direction, to substantially nullify the transmission of driving torque exceeding a predetermined value from the grinding wheel through the work piece to said control wheel;

5. A centerlessgrinding machine. as defined in claim 4, together with means for variably regulating the responsive action of said. torque nullifying means in proportionate ratio to torque g, forces of difierentvalues.

6; In a centerless grinding machine, a power driven: grinding wheel an oscillatable control wheel in peripherally opposed relation to said grinding wheel to: form a grinding throat, means for manually operating said control wheel, a relatively movable member operatively connected with said manual control wheel operating means, and means hydraulically-- controlling movement of said member in the manual oscillation of said control wheel in: grinding direction, to nullify thedriving efi'ect upon the control'wheel of torque force transmitted from the grinding wheel, having a value exceeding the manual torque force required to oscillate the. control wheel.

7. A centerless grinding machineas defined in claim 6, wherein said hydraulic control means includes means operative in the reverse oscillation of the control wheel to render said hydraulic control" means ineffective. to influence movement of said member.

8. A center-"less grinding machine as defined in claim 6, wherein said hydraulic control means includes a manually adjustable valve operable to variably control hydraulic resistance to movement of said member in proportionate ratio to the values of excessive torque forces.

9. In a centerless grinding machine, a power driven grinding wheel, anoscillatable control wheel in peripherally opposed relation to said grinding wheel to form a grinding throat, means for manually oscillating said control wheel, a cylinder, a reciprocable member in said cylinder operatively connected with said manual control wheel operating means, a reversoir for hydraulic medium and passages connecting opposite ends of the cylinder with said reservoir, and flow controlling valve means between one end of the cylinder and the reservoir producing hydraulic resi'stanceto movement or said member in response totorque forces on the control wheel exceeding the value of the manual torque force required to oscillate said wheel in work grinding direction.

10. A oenterless grinding machine as defined in claim 9, wherein said valve means includes a spring seated check valve preventing fluid flow from said cylinder end into the reservoir, a bypass aroundsaid valve, and a metering valve in said by-pass for variably regulating resistance of the hydraulic mediumto movement of said reci'procable member.

11. In a centerless grinding machine, a work control'wheel' selectively operable by power driven ormanu-ally operative means; said latter means comprising a rotatable and axially movable shaft,

nected with the control Wheel, together With independently operable means for rotating and axially shifting said shaft, means for releasably establishing a driving connection between said shaft and the control wheel by axially shifting said shaft, an energizing unit for the power driven means, and means operable by said shaft to effectively actuate said energizing unit in the axial movement of said shaft to disconnect the same from the control wheel.

12. A centerless grinding machine as defined in claim 11, wherein said energizing um't comprises a normally open electric switch, and said actuating means comprises a member fixed to the shaft directly actuating and holding said switch in circuit closing position.

13. A centerless grinding machine as defined in claim 11, wherein said last named means is fixed to one end of said shaft and a manually operable lever for rotating said shaft is fixed to the opposite end thereof.

14. A centerless grinding machine as defined in claim 11, wherein the means for axially shifting said shaft comprises a manually operable member mounted to rotate upon an axis normal to the shaft axis and having means coacting with means on said shaft to impart axial movement thereto while permitting free rotation of said shaft.

15. A centerless grinding machine as defined in claim 11, wherein the means for axially shifting said shaft comprises a manually operable member mounted to rotate about an axis normal to the shaft axis, said member having an eccentrically oifset stud projecting from one end thereof and coacting with spaced annular parts on said shaft upon rotation of said member to axially shift the shaft in each direction.

10 16. In a centerless grinding machine, a power driven grinding wheel, a control wheel peripherally opposed to said grinding wheel to form a work grinding throat, and a hydraulic torque 5 neutralizing unit operatively connected to said control wheel to substantially nullify the transmission of driving torque exceeding a predetermined value from the grinding wheel through the workpiece to the control wheel.

17. The combination defined in claim 16, together with means for variably regulating the responsive action of said torque neutralizing unit in proportionate ratio to torque forces of different values.

18. The combination defined in claim 16, wherein said torque neutralizing unit includes means automatically operative to render said unit functionally inactive upon rotation of the control wheel relative to the grinding wheel when theg0 latter wheel is not in grinding contact with a work piece.

GEORGE E. HIEBER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 30 1,938,757 Einstein et al. Dec. 12, 1933 2,091,655 Scrivener Aug. 31, 1937 2,142,022 Ernst et al. Dec. 27, 1938 2,346,851 Lloyd Apr. 18, 1944

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