US3145513A

US3145513A - Steady rests

Info

Publication number: US3145513A
Application number: US244467A
Authority: US
Inventors: Gordon H Porath
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-12-13
Filing date: 1962-12-13
Publication date: 1964-08-25
Anticipated expiration: 1981-08-25
Also published as: DE1502551A1; FR1379903A; GB1064760A

Description

G. H. PQRATH Aug. 25, 1964 STEADY RESTS 5 Sheets-Sheet 1 Filed Dec. 15, 1962 INVENTOR. GORC ON 1'7. PORH 7' BY y w,

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Aug. 25, 1964 G. H. PORATH STEADY RESTS 5 Sheets-Sheet 2 Filed Dec. 15, 1962 BY 23% f d/K 4M Aug. 25, 1964 G. H. PORATH 3,145,513

STEADY RESTS Filed Dec. 15, 1962 5 Sheets-Sheet 3 I I i J 76 INVENTOR. GORDON 6'. Penn? w M A rro/e/vsrs Aug. 25, 1964 G. H. PORATH STEADY RESTS 5 Sheets-Sheet 4 Filed Dec. 13, 1962 IN VENTOR.

ATTORNEYS Aug. 25, 1964 PQRATH 3,145,513

STEADY RESTS Filed Dec. 13, 1962 5 Sheets-Sheet 5 INVENTOR 50x00 0'. POAPATH United States Patent 3,145,513 STEADY RESTS Gordon H. Porath, 6101 Concord, Detroit, Mich. Filed Dec. 13, 1962., Ser. No. 244,467 28 Claims. (Cl. 51-238) This invention relates to steady rests for rotatably supporting workpieces and particularly to steady rests for rotatably supporting engine camshafts in position for grinding.

One of the operations in the forming of engine camshafts is the grinding of the cam lobe surfaces of engine camshafts. At the present time, this is accomplished in grinding machines which rotatably support the ends of the engine camshaft and drive the engine camshaft during the grinding. Steady rests in the form of mechanical bearing supports are provided for the camshaft bearing surfaces at longitudinally spaced points along the engine camshaft for the two-fold purposes of first removing any distortion in the axis of the engine camshaft which has been formed during prior manufacturing steps and, second, holding the axis of the camshaft as stable as possible during the grinding. It is not uncommon in such engine camshafts to find that the axis of the camshaft is distorted in excess of 0.010 inch. The major disadvantage with the mechanical steady rests presently used in such machines is that they have a metal-to-metal contact with the portions of the engine camshaft and thereby tend to wear necessitating their frequent repair and replacement. In addition, any fiaw in the surfaces of the steady rests tends to mar the contacted surfaces of the engine camshaft. Moreover, the bearing surfaces are often out of round or vary in diameter thereby introducing additional inaccuracies.

It is therefore an object of this invention to provide an improved steady rest which will more effectively support the engine cam shaft and remove any distortion in the axis thereof.

It is a further object of this invention to provide such a steady rest which will support the engin cam shaft without metal-to-metal contact in both the static and rotary positions thereof.

It is a further object of this invention to provide such a steady rest which utilizes a pressurized liquid from an external source as the load supporting medium between the steady rest and the workpiece.

It is a further object of this invention to provide such a steady rest which will effectively support the workpiece at all speeds of rotation.

It is a further object of this invention to provide such a steady rest which will utilize the same liquid as is used as a coolant in the grinding operation.

It is a further object of this invention to provide a grinding machine arrangement including such steady rests wherein operation of the machine is prevented except where the workpieec is in position in the steady rest.

It is a further object of this invention to provide a grinding machine having such steady rests wherein opera tion of the machine is prevented unless liquid is flowing to the steady rests.

It is a further object of this invention to provide an adjustable steady rest which can be used for workpieces of varying diameters.

Basically, each steady rest which is associated with a machine includes an opening which is adapted to surround a portion of the workpiece such as the engine cam shaft. A plurality of pressure pockets or pads are provided around the opening and an orifice is associated with each pressure pad. Liquid under pressure is provided to each orifice. When the workpiece is placed in position in the steady rest and the liquid is supplied to the steady rest, a film of liquid flows continuously in laminar fashion at 3,145,513 Patented Aug. 25, 1964 a low velocity between the adjacent surfaces of the steady rest and the workpiece in such a manner that the liquid dissipates its pressure a short distance from the pressure pad. Any load or distortion on a workpiece causes the workpiece to tend to move toward one pad or pads so that the flow of liquid from the pad is restricted; since the liquid is being supplied continuously in each pad, the pressure in the pads increases. At the same time, the workpiece tends to move away from the opposite pad or pads opening or relieving the restriction to flow and the pressure in the pad or pads decreases. A pressure differential is thus created which moves the workpiece to its centered position relative to the steady rest. The cooperative action of a plurality of steady rests spaced longitudinally along the engine shaft removes the distortion in the engine cam shaft and maintains the axis thereof in a stable position. Because there is never any metal-to-metal contact, there is no wear either on the steady rest or the workpiece.

In the drawings:

FIG. 1 is a fragmentary plan view of a grinding machine embodying the invention.

FIG. 2 is a partly diagrammatic plan view of a modified form of grinding machine.

FIG. 3 is a side elevation of one of the steady rests shown in FIG. 1.

FIG. 4 is a sectional view taken along the line 4-4 in FIG. 3.

FIG. 5 is an end view taken in the direction of the arrow 5 in FIG. 3.

FIG. 6 is a sectional view taken along the line 66 in FIG. 5.

FIG. 7 is an enlarged fragmentary part sectional view of a portion of the steady rest shown in FIG. 5.

FIG. 8 is. a schematic hydraulic and electrical diagram for the machine embodying the invention.

FIG. 8A is a fragmetary sectional view on an enlarged scale of a typical capillary tube used in the steady rests.

FIG. 9 is a side view of a modified form of steady rest.

FIG. 10 is a fragmentary sectional view on an enlarged scale taken along the line 1010 in FIG. 9.

FIG. 11 is a fragmentary perspective view of a part of the apparatus shown in FIGS. 9 and 10.

FIG. 12 is a partly diagrammatic view showing the manner in which the steady rest shown in FIGS. 9-11 is used.

, FIG. 13 is a diagrammatic showing of the manner in which the pressure pads function in the steady rest embodying the invention.

Referring to FIG. 1, which shows a portion of a grinding machine, an engine cam shaft C having longitudinally spaced cam surfaces S which are to be ground is rotatably mounted between centers Ida and 10b of the grinding machine. Center 10:: is driven and is provided with a pin which engages an opening in the end of the camshaft to drive the camshaft. The pin is non-circular so that only a rotational force is provided on the camshaft. This is to accommodate any eccentricity between the center 10a and the opening in the camshaft. The above arrangement is conventional.

In order to support the engine camshaft intermediate its ends during grinding and to remove any distortion in the axis thereof during the grinding, steady rests 11 are mounted at spaced points along the bed 12 (FIG. 5) of the machine to support the engine camshaft C at the cylindrical bearing surfaces B.

Referring to FIGS. 1, 3-5, each steady rest 11 comprises a base 13 which has projections 14 at its ends Which receive bolts 15 which are threaded into 'T-nuts 15a riding in a T-slot 15b in the bed 12. Base 13 also includes a downwardly extending flange 16 adapted to engage the rear surface 17 of the bed 12 and a downwardly extending flange 18 extending along the front surface of the bed 12. Locking screws 19 extend through the flange 18 (FIG. into engagement with a spacer block 20 and press block 20 against the front surface 21 of the bed 12 to lock the base 13 in adjusted position on the bed 12. In this manner, each steady rest 11 can be fixed at any point longitudinally on the bed 12.

Referring to FIGS. 37, each steady rest includes a primary slide 22 which is slidably mounted on the flat upper surface of the face 13 and guided by keepers 13a. Provision is made for positively locking the horizontal position of primary slide 22. on base 13 and includes triangular locking blocks 23 having inclined faces 24 which engage an inclined wall 25 projecting downwardly from the underside of a recess 26 in the slide 22. Wall 25 is inclined or skewed with respect to the axis of movement of primary slide 22 on base 13. Each block 23 is held in adjusted position by a screw 24' threaded into the base and engaging the block 23. By moving the blocks into contact with the inclined Wall 25, the blocks are positioned to lock the wall and, in turn, the primary slide 22 in position. A lock or jam nut 2601: each screw 24' holds the blocks in adjusted position. By this arrangement, the steady rests 11 are adjusted and locked in and out horizontally of bed 12 transversely of the axis of the workpiece.

A secondary slide 30 is slidably mounted on an inclined face 32 of the primary slide 22 and guided by keepers 31 in order to provide for vertical adjustment of the steady rest. The slide 30 is locked in position on the surface 32 by an arrangement which includes triangular blocks 33 which engage a skewed or inclined wall 34 and are adjusted by screws 35 held in adjusted position by lock nuts 36 in a manner identical to the manner of locking of the primary slide 22 on the base 13.

A pair of separable or

partible sections

40, 41 are provided on the secondary slide 30. Section 40 forms a part of the slide 30;. The upper section 41 is hinged to the lower section 40 along the longitudinal axis of the machine parallel to the axis of the workpiece or cam shaft by a pin 42 which extends through an opening in the section 41.

Sections

40, 41 are formed with mating surfaces 44, 45 and interengaging registering grooves 47 and teeth 46. The opposed surfaces 44, 45 are formed with semi-cylindrical surfaces 48, 49 which define an opening 50 that is adapted to surround one of the bearing B of the cam shaft C.

Referring to FIGS. 4 and 8A, the surfaces 48, 49 are formed with circumferentially spaced pockets or pressure pads 51. Each pressure pad 51 comprises a recess in its corresponding surface to which liquid is supplied at a predetermined pressure. An orifice formed by a capillary tube 53 is provided for each pressure pad 51. The capillary tube 53 is set in a-set screw 54 threaded into an opening 55 that communicates with the pad 51. The end 56 of the screw includes an Allen head depression 57 for engagement by a tool. O-ring 58 provides a seal.

Hydraulic fluid under pressure from an external source is provided to the pressure pads 51 on the lower section 40 through an inlet 59 to passageway 60 and branch passages 61, 62, 63. Similarly, liquid is supplied to the pressure pads 51 of the upper section 41 through an inlet 64, drilled passageways 65, 66 and branch passages 67, 68.

Any viscous liquid, such as machine oil, may be used. However, in the cast of a grinding machine, it is preferred that the liquid comprise the same coolant that is used in grinding, such as a water soluble oil or waxed based fluid in water.

The liquid supplied to the inlets 59, 64 is at substantially predetermined constant volume-and pressure. The orifices for each pressure pad are selected in such a manner that in each particular steady rest the pressures in the pressure pads are'equal.

When a steady rest is placed in position and the

sections

40, 41 are brought into mating relation, a laminar film of liquid flows continuously at low velocity between the surfaces 48, 49 of the

sections

40, 41 and the surface of the engine cam shaft and the adjoining surfaces and the pres sure of the liquid drops to zero as it leaves the surfaces 48, 49. The number and size of the pressure pads 51 is such as to provide a force sufiicient to support the engine cam shaft and maintain its axis stable.

The size of the opening 50 defined by the surfaces 48, 49 is so adjusted relative to the surface of the engine cam shaft which is surrounded by the

sections

40, 41 that a thin film of liquid flows at all times in laminar fashion at low velocity between the surfaces and preferably sub stantially all the pressure of the liquid is dissipated by the time the liquid has passed from the pad to the periphery of the surface in question.

The space between the surfaces of opening 50 and the bearing surface B may range between two-thousandths (0.002) of an inch and one ten-thousandth (0.0001) of an inch and preferably between one-thousandth (0.001) of an inch and one ten-thousandth (0.0001) of an inch. Although it is preferred that the space be the same around the opening, any inaccuracies due to out of round condition of the bearing surface of the workpiece will be compensated for provided at least some portions define a space within the above limits.

Since each of the steady rests tends to retain the portion of the engine camshaft centered and stable relative to the steady rests, if the openings 50 of succeeding steady rests are accurately aligned, the steady rests will remove any distortion in the axis of the engine camshaft.

The provision of low velocity laminar flow of liquid between the surfaces of the

sections

40, 41 and the engine camshaft effectively eliminates any friction because there is no metal-to-metal contact. The force required to remove any distortion in the engine camshaft and the forces on the engine camshaft during the grinding are compensated for by the flow through the pressure pads thereby maintaining a stable accurate axis for the engine camshaft. Any minor surface or machining inaccuracies in the surfaces 48, 49 or the adjacent surface of the engine camshaft do not adversely affect the action and the fully compensated fiow accommodates for such surface or machining inaccuracies producing an ultra-precise, stable, smooth, vibration-free axis for the engine camshaft.

FIG. 8 represents a combined hydraulic and electrical circuit for the apparatus. As shown, a pump driven by an electric motor 81 supplies liquid through a line 82 and line 83 through a filter 84 which may be of the type that has an indicator switch in the event that the liquid has particles of excessive size therein. The liquid then passes through line 85 through a one-way valve 86 to the steady rests 11 represented by blocks in FIG. 8. Since the liquid preferably is the same as the liquid coolant used in the grinding operation, it is returned through the central collecting system through a control valve 87 and filter 88 which may be of the endless fabric type and micronic filter 89 similar to filter 84 to the inlet of the pump 80.

When an operator places an engine camshaft in the machine and the

sections

40, 41 of the steady rest are closed, switches 74 are also closed. These switches 74 are shown more specifically in FIG. 1 and comprise plungers 91 that are actuated by eccentric 75. When the operator then depresses the master switch 93 (FIG. 8), power is supplied to a vent valve 94 that prevents the normal flow of fluid from line 82 through line 95 to line 95' and permits the fluid then to flow through a line 83 and 85 to the steady rests. A pressure relief valve 96 is provided in the line 95. When the pressure in the line 85 builds up to the desired pressure when the steady rest sections are fully closed, a pressure switch 97 is actuated to supply power to the motor 98 for driving the grinding machine.

By this arrangement, the switches 74 prevent the application of liquid to the steady rests until the steady rests are being closed and the pressure switch 97 prevents operation of the grinding machine until the liquid is flowing at the predetermined pressure. As a result, the machine will not operate until the pressure pads are functioning properly to form the desired support for the engine camshaft.

The manner of operation of the steady rests can be more readily understood by referring to FIG. 13 which represents the relative arrangement provided by the pressure pads 51. In the event that a force is applied to the engine camshaft by the load of the grinding wheel or if a distortion of a portion of the engine crankshaft tends to be out of alignment with the axis of the opening 50 of the steady rest when the engine camshaft is first placed in the steady rest, the pressure in the pad 51 represented by the arrow P increases because of the restricting action and the pressure in the opposed pad represented by the arrow P decreases because of the unrestricting action so that a force is applied on the engine camshaft upwardly tending to return the engine camshaft to its initial position. Because the steady rests are designed with internal supporting pressures far in excess of applied loads and because of the minute clearance dimensions, it can readily be tmderstood that the relative movements herein described are very slight. In fact, the movements are so slight that they cannot be measured.

A steady rest embodying the invention provides a very accurate control of the axis of the workpiece which is supported and since there is no wear the accuracy is maintained indefinitely. The steady rest has substantial load carrying characteristics to make it resistant to shock so that it can be used without damage for prolonged periods.

In order to insure that dirt and other cuttings from the grinding operation do not contact the surfaces of the teeth and grooves 46, 47, passages 7G 73 are provided which supply liquid under pressure to the surfaces of teeth 46 as the

sections

41, 42 are closing. A switch 74- is provided adjacent the support and is actuated by an eccentric 75 on pin 42 to initiate passage of the fluid just prior to the full closing of the

sections

41, 42.

In order to insure locking of the sections, a U-shaped yoke 76 is pivoted to a pin 77 on the fixed slide 30 and is provided with a handle 78 so that it can be readily swung to bring transversely curved surface 79 of the bight portion thereof into overlying relation with a flat incline 80 on the section 41 and thereby lock the section 41 in position. This provides a means for readily locking the

sections

40, 41 together. The interengaging teeth 46 and grooves 47 provide for absolute registration of sections 49, 41 so that the steady rest is not affected by any wear in the hinge and particularly pin 42 due to opening and closing.

In the form of the invention shown in FIGS. 9-12, a universal steady rest is provided for rotatably supporting the end of a workpiece W which is held in a chuck as shown in FIG. 12. The steady rest comprises two pivoted

sections

101, 102 which are connected and hinged to one another by a pin 103, locked and closed by a pivoted bolt 104 and nut 105. The lower section 192 is mounted on the bed of the machine and provided with a pair of adjustable radially movable pad members 1596 while the upper section 1431 is provided with one radially movable pad member 106. As shown in FIG. 10, each pad member comprises a pad body 197 which is movable radially in an opening in the section and held in locked position radially by a screw 103. Each body 107 includes an axial opening 109 into which a screw 110 is threaded. The screw 119 supports, as by silver soldering, a capillary tube 111 to provide an orifice. The lower end of the body is formed with a pressure pad 112 (FIG. 11). Liquid is supplied by a flexible tube 113 to the passage to provide liquid to the orifice and, in turn, the pressure pad 112. A second passage 114 extends axially of the body and is connected to a gauge 115 (FIG. 9).

In practice, the workpiece is initially positioned with the aid of a micrometer indication. The steady rest is then brought in position. The fluid flow is initiated and the bodies 107 are adjusted radially inwardly and out-. wardly until the pressures indicated by the gauges are equal. This will indicate that the workpiece W is being held centrally. When the pressures have been made equal, the workpiece W is rotated by hand and the adjustment of the screws 168 is continued until there is no change in pressure as the workpiece W is rotated. At the same time, the micrometer indicator is used to check alignment with the center of the chuck. In this manner, the end of the workpiece is adjusted so that it will be thereafter supported in a stable, frictionless manner during rotation thereof by the chuck 118 (FIG. 12).

In the form of the invention shown diagrammatically in FIG. 2, four steady rests are provided. The centers 10a, 10b are eliminated, the entire weight of the camshaft being supported by the steady rests and the pin serving to rotate the camshaft at the proper speed for being worked on. Only limit stops 116, 117 are provided to prevent axial movement of the workpiece but do not support any load. By this modified arrangement, in addition to the advantages heretofore mentioned, inaccuracies due to the hearings in the tailstock and headstock which would be introduced by the centers are entirely eliminated. In addition, any error due to misalignment of the centerdrilled on the ends of the workpiece with respect to the center of the bearings B is entirely eliminated. Finally, the camshaft is supported during grinding in the identical manner that it will be used in the engine, that is, at the bearings thus further increasing the accuracy of the grinding of the camshaft.

. I claim: a

1. In a grinding machinefor grinding the surfaces of an engine camshaft or the like, the combination comprismg a grinding machine,

a plurality of steady rests positioned on said machine for supporting the engine camshaft at longitudinally spaced points during grinding, 1

each ,said steady rest having a cylindrical opening adapted to receive and surround a portion of said engine camshaft,

said steady rest having a plurality of circumferentially spaced pressure pads about said opening,

an orifice associated with each pressure pad,

and means for supplying liquid under pressure to each said orifice,

the pressure of liquid in the being equal,

such that when an engine camshaft is placed in position with the opening surrounding said portions of the cam shaft, a pressurized film of liquid flows continuously through the pressure pads between the surfaces defining the opening and the surfaces of theportions of the engine camshaft surrounded thereby so that forces are applied to the engine camshaft to remove any axial distortion therein and maintain the axis of the engine camshaft in a stable position relative to the steady rest.

2. The combination set forth in claim 1 wherein said liquid comprises the grinding coolant,

means for collecting said coolant the steady rest,

and means for filtering the coolant after it is collected and before it is returned to the steady rest.

3. The combination set forth in claim 1 wherein the orfice of each said pressure pad is positioned in its corresponding steady rest.

4. The combination set forth in claim 1 wherein each said steady rest comprises separable sections which are partible to facilitate the insertion of the engine camshaft.

5. The combination set forth in claim 1 wherein each said steady rest includes means for adjusting said steady pads of each steady rest and returning it to J rest vertically and horizontally relative to the grinding machine.

6. In a grinding machine for grinding the surfaces of an engine camshaft or the like, the combination comprising a grinding machine,

a plurality of steady rests mounted at longitudinally spaced points on said machine for supporting the intermediate longitudinally spaced portions of the engine camshaft,

each said steady rest comprising separable sections which are adapted to part and receive the engine camshaft,

each said section having a surface cooperating to form a cylindrical opening for receiving and surrounding a portion of the camshft,

said surfaces of said sections being formed with circumferentially spaced pressure pads,

an orifice in said corresponding sections associated with each pressure pad,

means for supplying liquid under pressure to each said orifice,

the pressure of liquid in the pads of each said steady rest being equal,

such that a pressurized film of liquid flows continuously between the surfaces of each said steady rest and the corresponding portion of the engine camshaft so that forces are applied to the engine cam shaft tending to hold the engine camshaft in a stable position relative to its steady rest and removing any distortion of the engine camshaft.

7. The combination set forth in claim 6 including means for locking said separable sections in closed position.

8. The combination set forth in claim 6 wherein said separable sections are mounted on a base,

said base being adjustable horizontally of the machine.

9. The combination set forth in claim 8 including a support on said base,

said partible sections being mounted on said support,

said support being adjustable vertically relative to said base.

10. The combination set forth in claim 8 wherein said base is provided with an inclined plane,

said support being mounted on said inclined plane and movable relative thereto,

means for locking saidsupport in adjusted position on said inclined plane,

thereby providing vertical adjustment of said support relative to said base.

11. The combination set forth in claim 6 wherein said sections. of said steady rest are hinged about an axis parallel to the longitudinal axis of the grinding machine.

12. In a grinding machine for grinding the surfaces of an engine camshaft or the like, the combination comprismg a grinding machine,

a plurality of steady rests positioned on said machine for supporting the engine camshaft at longitudinally spaced points during grinding,

means engaging and driving the camshaft,

each said steady rest having a cylindrical opening adapted to receive and surround a portion of said engine camshaft,

each said steady rest comprising partible sections which are partible to facilitate the insertion of the engine camshaft,

an orifice associated with each pressure pad,

means for supplying liquid under pressure to each said orifice,

the pressure of liquid in the pads of each steady rest being equal,

such that when an engine camshaft is placed in position k with the bearing opening surrounding the portions of the camshaft, a pressurized film of liquid flows continuously between the surfaces defining the opening and the surfaces of the engine camshaft surrounded thereby through the pressure pads so that forces are applied to the engine camshaft to remove any axial distortion therein and maintain the axis of the engine camshaft in a stable position relative to the steady rest,

and means responsive to the how of pressurized fluid to the orifices of the steady rest for controlling the operation of the drive means for driving the engine camshaft.

13. In a grinding machine for grinding the surfaces of an engine camshaft or the like, the combination comprising a grinding machine,

a plurality of steady rest positioned on said machine for supporting the engine camshaft at longitudinally spaced points during grinding,

each said steady rest having a bearing opening adapted to receive and surround a portion of said engine camshaft,

an orifice associated with each pressure pad,

means for supplying liquid under pressure to each said orifice,

the pressure of liquid in the pads of each steady rest being equal,

such that when an engine camshaft is placed in position with the bearing opening surrounding the portions of the camshaft a pressurized film of liquid flows continuously between the surfaces defining the opening and the surfaces of the engine camshaft surrounded thereby through the pressure pads so that forces are applied to the engine camshaft to remove any axial distortion therein and maintain the axis of the engine camshaft in a stable position relative to the steady rest,

and means responsive to the positioning of the engine camshaft in the steady rests for controlling the flow of liquid to the steady rests.

14. The combination set forth in claim 13 including means for engaging and driving the camshaft,

a switch responsive to the flow of pressure in the hydraulic circuit of the steady rests and electrically conneoted to the drive mechanism for the grinding machine whereby the grinding machine will only be energized when liquid is flowing to the steady rests at the proper support pressure.

15. In a machine for rotatably supporting a workpiece,

the combination comprising a machine,

a plurality of steady rests positioned on said machine for supporting the workpiece at longitudinally spaced points,

each said steady rest having an opening adapted to re ceive and surround a portion of said workpiece,

an orifice associated with each pressure pad,

means for supplying liquid under pressure to each said orifice,

the pressure of liquid in the pads of each steady rest being equal,

such that when said workpiece is placed in position with the opening surrounding said portions of the workpiece, a pressurized film of liquid flows continuously through the pressure pads between the surfaces de fining the opening and the surfaces of the engine camshaft surrounded thereby so that forces are applied to the engine camshaft to remove any axial distortion therein and maintain the axis of the engine camshaft in a stable position relative to the steady rest.

16. The combination set forth in claim wherein the orifiw of each said pressure pad is positioned in its corresponding steady rest in close proximity to said part.

17. The combination set forth in claim 15 wherein each said steady rest includes means adjusting said steady rest vertically and horizontally relative to the machine.

18. The combination set forth in claim 15 including means for locking said separable sections in closed position.

19. The combination set forth in claim 15 wherein said separable sections are mounted on a base,

said base being adjustable horizontally of the machine.

20. The combination set forth in claim 19 including a support on said base,

said partible sections being mounted on said support,

said support being vertically adjustable relative to said base.

21. The combination set forth in claim 20 wherein said base is provided with an inclined plane,

said support being mounted on said inclined plane and movable relative thereto,

means for locking said support in adjusted position on said inclined plane,

thereby providing the vertical adjustment of said support relative to said base. 22. The combination set forth in claim 15 wherein said sections of said steady rest are hinged about an axis parallel to the longitudinal axis of the grinding machine. 23. The combination set forth in claim 15 including means responsive to the positioning of the engine camshaft in the steady rests for controlling the flow of liquid to the steady rests.

24. In a machine for rotatably supporting a workpiece, the combination comprising a machine, a steady rest positioned on said machine for supporting the workpiece at a point along its length,

said steady rest having a cylindrical opening adapted to receive and surround a portion of said workpiece.

an orifice associated with each pressure pad,

means for supplying liquid under pressure to each said the pressure of liquid in the pads of each steady rest being equal,

such that when said workpiece is placed in position with the opening surrounding said portion of said workpiece a pressurized film of liquid flows continuously through the pressure pads between the surfaces defining the opening and the surface of said workpiece surrounded thereby so that forces are applied to the workpiece to maintain the axis of said workpiece in a stable position relative to the steady rest.

25. In a machine for rotatably supporting a workpiece, the combination comprising a machine,

a steady rest mounted on said machine for rotatably supporting a portion of the workpiece,

said steady rest comprising separable sections which are adapted to part and receive the workpiece, said section supporting radially movable bodies having surfaces cooperating to define portions of a cylinder for receiving and surrounding a portion of the worlo piece, the surfaces of said bodies being formed with circum ferentially spaced pressure pads,

an orifice in the corresponding body associated with each pressure pad,

means for supplying liquid under pressure to each said the pressure of liquid in the pads of each said steady rest being equal,

such that a pressurized film of liquid flows continuously between the surfaces of said steady rest and the corresponding portion of the workpiece so that forces are applied to the workpiece tending to hold the worlo piece in a stable position relative to its steady rest.

26. The combination set forth in claim 25 wherein said sections of said steady rest are hinged about an axis parallel to the longitudinal axis of the grinding machine.

27. The combination set forth in claim 25 including a pressure gauge mounted on each said body and communicating with the pressure pad of said body.

28. In a grinding machine for grinding the surfaces of an engine camshaft or the like, the combination compris mg a grinding machine,

a steady rest positioned on said machine for supporting the engine camshaft during grinding,

said steady rest having a cylindrical opening adapted to receive and surround a portion of said engine cam shaft,

an orifice associated with each pressure pad,

and means for supplying liquid under pressure to each said orifice,

the pressure of liquid in the pads of said steady rest being equal,

such that when an engine camshaft is placed in position with the opening surrounding said portions of the camshaft, a pressurized film of liquid flows continuously through the pressure pads between the surfaces defining the opening and the surfaces of the portions of the engine camshaft surrounded thereby so that forces are applied to the engine camshaft to remove any axial distortion therein and maintain the axis of the engine camshaft in a stable position relative to the steady rest.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. IN A GRINDING MACHINE FOR GRINDING THE SURFACES OF AN ENGINE CAMSHAFT OR THE LIKE, THE COMBINATION COMPRISING A GRINDER MACHINE, A PLURALITY OF STEADY RESTS POSITIONED ON SAID MACHINE FOR SUPPORTING THE ENGINE CAMSHAFT AT LONGITUDINALLY SPACED POINTS DURING GRINDING, EACH SAID STEADY REST HAVING A CYLINDRICAL OPENING ADAPTED TO RECEIVE AND SURROUND A PORTION OF SAID ENGINE CAMSHAFT, SAID STEADY REST HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED PRESSURE PADS ABOUT SAID OPENING, AN ORIFICE ASSOCIATED WITH EACH PRESSURE PAD, AND MEANS FOR SUPPLYING LIQUID UNDER PRESSURE TO EACH SAID ORIFICE, THE PRESSURE OF LIQUID IN THE PADS OF EACH STEADY REST BEING EQUAL, SUCH THAT WHEN AN ENGINE CAMSHAFT IS PLACED IN POSITION WITH THE OPENING SURROUNDING SAID PORTIONS OF THE CAM SHAFT, A PRESSURIZED FILM OF LIQUID FLOWS CONTINUOUSLY THROUGH THE PRESSURE PADS BETWEEN THE SURFACES DEFINING THE OPENING AND THE SURFACES OF THE PORTIONS OF THE ENGINE CAMSHAFT SURROUNDED THEREBY SO THAT FORCES ARE APPLIED TO THE ENGINE CAMSHAFT TO REMOVE ANY AXIAL DISTORTION THEREIN AND MAINTAIN THE AXIS OF THE ENGINE CAMSHAFT IN A STABLE POSITION RELATIVE TO THE STEADY REST.