US2347029A - Polishing machine - Google Patents

Description

April 18, 1944.. R. COS EY 2,347,029

V POLISHING MACHINE Filed March 23, 1942 2 Sheets-sheet 1 INVENTOR. HENRY R. COSTLEY E,E. BYCg I s ATTORNEY,-

April 18, 1944. COSTLEY I 2,347,029

POLISHING MACHINE Filed March 23, 1942 I 2 Sheets-Sheet 2 75 INVENTOR.

HENRY R CIOSTLLEY l5 ATTORNEY Patented Apr. 18, 1944 POLISHING MACHINE Henry R. Costley, Kenosha, Wis., assignor to Nash-Kelvinator Corporation, Kenosha, Wis., a corporation of Maryland Application March 23, 1942, Serial No. 435,766

9 Claims.

This invention relates to polishing machines and has particular reference to a machine for polishing a curved surface on a machine part. More particularly, the machine is designed to polish the cylindrical surface on the end of a rocker arm such as is used in an overhead valve type of internal combustion motor but the same machine may obviously be used to polish a curved surface on other types of machine parts.

It is an object of this invention to provide a polishing machine in which the abrasive material employed will not become grooved or otherwise deformed by repeated polishing operations on similar parts.

It is another object of this invention to provide a machine which will employ an abrasive covered belt in place of a solid abrasive wheel.

It is another object of this invention to provide a machine which will automatically move the work piece into contact with all portions of the abrasive surface during the polishing operation.

It is another object of this invention to provide a polishing machine to which the part to be polished may be easily and quickly attached.

It is another object of this invention to provide a machine which will successively bring all portions of a cylindrical surface into contact with an abrasive surface.

It is another object of this invention to provide a polishing machine which will successively bring all parts of a curved surface into contact with the polishing surface at a maximum pressure while at the same time polishing those portions of the surface on each side of the area of maximum pressure with successively reduced pressure.

Other objects and advantages of this invention will be apparent from a consideration of the fol.- lowing description and claims and the attached drawings, of which there are two sheets, and in which- Figure 1 represents a front elevation of the machine;

Figure 2 represents an end elevation of the machine;

Figure 3 represents a vertical sectional view taken along a plane indicated by the line 3-3 in Figure 1 and looking in the direction of the arrows and showing the work piece in place on the machine;

Figure 4 represents an enlarged diagrammatic view showing the relationship between the work piece and the various moving parts of the machine;

Figure 5 represents a plan view of the machine;

Figure 6 represents a partial sectional view taken along a plane indicated by the line 6--6 in Figure 2 and looking in the direction of the arrows; and

Figure '7 represents a sectional view taken along a plane indicated by the line 'l'! in Figure 6 and looking in the direction of the arrows.

The machine consists of a main base Ill supported upon a suitable surface I 2. The base 16 may be of any suitable construction, such as a casting, having sufiicient strength to support the various parts of the machine.

Positioned on one end of the upper surface of the main base ID are the work supporting head [4 and pulley supporting head I6. The pulley supporting head may conveniently be formed by casting as an integral part of the main base I6 and is apertured to receive a bearing 18 in which the pulley shaft 20 is rotatably mounted.

Attached to the supporting surface l2 to the rear of the polishing machine is an electric motor 22 on the shaft of which is mounted a driving wheel 24. A belt 26 is passed around the wheel 24 and the end of the pulley shaft 20. The drawings illustrate the end of the pulley shaft 26 to be slightly enlarged as at 28 to receive the belt 26 but if desired, a separate pulley wheel could be mounted on the shaft 20. The belt 26 may be made of fabric or paper or some other suitable material, the outside surface of which is coated with an abrasive material, such as emery or sand, of the desired abrasive qualities.

The work support head l4 positioned on the opposite end of the main base It) may also be cast integrally with the base I0 and is provided with spaced end walls 30 and 32 projecting upwardly above the ends thereof and approximately normal to the axis of the pulleyshaft 29. .The end wall 30 is apertured to receive the bearing 34 while the end wall 32 is apertured to receive the sleeve 36 which is press fitted in the end wall and co-axially arranged with respect to the bearing 34. Positioned within the sleeve 36 are the spaced bearings 38 and 46 which, along with the bearing 34, are arranged to rotatably and slidably support the main shaft 42. It will be noted that the end of the sleeve 36 projects outwardly from the end wall 32 a shortdi'stance toward the pulley shaft 20. v

The end of the main shaft 42 projects beyond the end of the sleeve 36 and is provided with a threaded end portion as at 44 (see Figure 5) on which is threaded the base of a cylindrical collar 46. The collar is arranged to fit closely around the outer end of the sleeve 36 to prevent dust from the polishing operation from coming in contact with the bearings 38 and 4!).

Threaded on the end portion 44 of the shaft 42 outside of the collar 46 is an arm 48 which holds the collar 46 in place and which is itself held in place by means of a set screw 50 (see Figure 3) so that the arm 48 and collar 46 are secured to, and rotatable with, the shaft 42. It will be noted that the main shaft 42 is parallel to the pulley shaft 20 but is spaced above and to the right of the axis of the pulley shaft 20 by a distance which will be more particularly defined presently and which is most clearly illustrated in Figures 2 and 3. The main shaft 42 also terminates short of the plane of the end of the pulley shaft 20 (see Figures 1 and '5).

The arm 48 extends radially from the threaded end 44 of the shaft 62 and carries the stub shaft 52 which is securely fastened to the arm 48 by the nut 54. The arm 48 also has attached thereto the L-shaped handle 56 by means of which the arm 48, stub shaft 52 andzmain shaft 42 may be rotated relative to the head (4 and pulley shaft 20. The stub shaft 52 is parallel to both the main shaft 42 and pulley shaft 20 and is eccentric with respect to the main shaft in all positions of the arm 48 with respect to the pulley shaft.

The stub shaft 52 is of such a diameter as to fit freely within the aperture formed in a rocker arm 58 (see Figure 3) The aperture 51 is the opening through which the rocker arm shaft extends when the rocker arm is installed in an engine. The rocker arm 58 is provided with the usual push rod engaging portion 60 and the valve actuating portion 62 having a cylindrical surface 64 which engages the end of the valvestem in the engine. It is this surface 64 which is desired to be polished. The surface '64 is a cylindrical surface curved about an axis, indicatedat 85, other than the axis of the shaft aperture: 51. It is immaterial whether -or not the axis 85 falls within any part of the rocker arm, the position of the axis being determined by the desired position and curvature of-the surface 64.

With particular attention to Figures 3 and 4, it will be notedthat thestub shaft-52 is offset from the axis of the main shaft 42 by a distance approximately equal to the distance between the center of curVature'BE and the center ofthe aperture '51. The axis of the main shaft 42 is positioned above the axis of the pulley'shaft 1-29 by'a distance approximately equal to the length of the radius of the en'd portion '23 of the pulley shaft, plus the length of the radius of curvature .of the surface '64 on the rocker .arm, plus the thickness of the belt '25. The axis o'fthe main shaft 42 is also offset slightly to the right, as viewed in'Figure 4, from the line of ara'dius of theend 28 of-the pulley shaft 28 drawn through the point of tangency '61 between the belt 28 and pulley .28 when the .belt is running freely around the pulley. As a result, when the rocker arm is rotated around the stub shaft -52 in a clockwise direction, the center of curvature 65 .of the surface t4 will approach the axis of the main shaft 4.2 and an element of the surface 64 will approach the belt 26 along a line 66 just offset from the l'll'lB'tOf tangency between the pulley and the :beltxtoward the free part of the belt.

When the valve actuating 8116.52 of the rocker arm 58 is pressed downwardly by the machine operator, it will slightly depress the belt '28 until the line 68 on the belt ispressed against the pulley shaft 2%) and will cause the .:belt to wrap slightly around the cylindrical surface 64. By rotating the arm 48 upwardly or in a clockwise direction as viewed in Figure 3 by lifting up on the handle 56 while maintaining the end 62 of the arm 48 depressed, successive portions of the cylindrical surface 54, as indicated by the broken lines 62A, will be brought into contact with the belt 26 at the line 88. The surface 64 being a cylindrical surface, the initial contact between the surface and the belt will form a line contact parallel to the axis of the pulley shaft 28 which will broaden into a partial cylindrical surface as the belt is depressed against the pulley. Attention is again called to the fact that the distance between the axes of the main shaft 42 and the stub shaft 52 is approximately equal to the distance between the axis of the aperture 51 in the rocker arm and the center of curvature of the surface 64 indicated at 65 so that when the rocker arm is pressed against the belt, rotation of the arm 48 and stub shaft 52 will cause the rocker armto be rotated about the center of curvature 65, thus bringing all parts of the surface 64 into contact with the belt.

In order to utilize all portions of the surface of the belt 26 and to prevent grooves from being formed in the abrasive surface by continued use of one portion of the belt, mechanism is provided for automatically shifting the main-shaft 42, arm 48 and stub shaft 52 alternately to the right and left with respect to the pulley shaft '23 and belt 26. By making the stub shaft 52 longitudinally movable, it is practical to use a wider -belt26 than could otherwise be used economically. This provides a stronger and longer lasting belt. The shifting mechanism is most clearly illustrated in Figures '6 and 7 and consists of a cam member ll] which is apertured to fit rotatably around the main shaft 42 between the end walls 30 and 32 of the work supporting head 14. The cam member 10 is provided with a cam groove i2 which straddles a pin 14 secured to the head l4 by the bolt E5. The cam member 10 is also provided with an .end portion '18 of reduced diameter. The end portion 18 is provided with ratchet grooves .80 and part of the'cam member 10 is provided with ratchet grooves 81 for a purpose which will be described presently.

The cam member 10 is retained against longitudinal movement with respect to the main shaft 42 by means of a collar 82 secured to theshaft by a pin .84 and by means of .an arm 86 which is positioned around the shaft at the opposite end of the cam member and is secured to the shaft by means of a pin 88. The arm 86 is provided with an-overhanging finger .90 which extends over the end portion 18 of the cam member and carries a pawl 92 which is spring pressed into the ratchet grooves in the end portion 13. A screw 94 serves to retain a spring 536 in place behind the pawl to urge the pawl into contact with the ratchet grooves.

The head underneath the cam member 10 is apertured to receive a second pawl 98 which is urged upwardly into engagement with the ratchet grooves 81 in the cam member by aspring 4439. A screw N32 serves to retain the spring 106 and pawl 98 in position.

As will be noted in Figure 7, the ratchet grooves '8! in the main part of the cam member 10 and the grooves in the end portion T8 are formed with radiallyarranged surfaces facing in the same direction so that as the ar-m'88 and'its finger portion Stare rotated in a clockwise direction along with the main shaft*42';t'0

which they are attached, the radially arranged surface of the pawl 92 will engage the radially arranged surfaces of the ratchet grooves 88 and will carry the cam member 19 along with the arm 8'6 and main shaft 62. At the same time, the sloping surface of the pawl 98, which is stationary, will be engaged by the sloping surfaces of the ratchet grooves 8! in the main portion of the cam member and they will cam the pawl 98 into the head M against the action of the spring Iilil so as not to interfere with the rotation of the cam member. However, when the arm 86 and its finger portion 9!) are rotated in a counter-clockwise direction along with the shaft 42, the pawl 92 will be cammed outwardly by engagement of its sloping surface with the sloping surfaces of the ratchet grooves 80 and will not carry the cam member '36 along with the shaft 42. During this movement, the radially arranged surface of the pawl 98 will engage the radially arranged surface of one of the ratchet grooves 8| in the main portion of the cam member l9 and will function as a stop to prevent rotation of the cam member ill by any'friction existing between the shaft 42 and the cam member 10.

As the cam member lii rotates in a single direction as explained above, the cam groove 12 will pass over the pin 14 and since the pin 14 is fixed relative to the head M, the cam member will be forced to move longitudinally along the axis of the main shaft 42 either to the right or to the left depending upon the position of the cam groove with respect to the pin. (See the position of the cam member indicated by the broken lines at WA in Figure 6.) Since the cam member 1% is held between the collar 82 and arm 83, this longitudinal movement will be imparted directly to the main shaft 42 which will thus be moved longitudinally along its axis of rotation. Movement of the shaft 52 will carry the arm 58 and stub shaft 52 longitudinally with respect to the pulley shaft 2b and belt 26 and cause the rocker arm 58 or work piece to be moved horizontally across the surface of the belt 223. The longitudinal travel of the cam groove l2 will, of course, be designed to provide for longitudinal movement of the work piece for a distance approximately equal tothe width of the belt The collar d3 which protects the bearings 38 and iii from dust may be provided with a pair of lugs 53% which project radially from the collar at angularly spaced intervals on each side of a stop pin We secured to the end wall 32. Adjustable bolts E68 may be secured in the lugs lfi l. to limit angular rotation of the arm 48 and main shaft 32 with respect to the head M. A semi-cylindrical hood l [0 may be positioned over the end walls 30 and 32 to enclose the cam mechanism and the hood may be held in place by means of cap screws I I2 threaded to the head l4.

From the above description it should be apparent that the operator of the machine will first place a rocker arm on the stub shaft 52 by passing the shaft through the aperture in the rocker arm and will rotate the rocker arm about the stub shaft until the cylindrical surface 64 is in contact with the belt 25 and the belt is pressed against the pulley shaft 26. Then by raising and lowering the handle 56, the arm 48 and stub shaft 52 may be rotated about the axis of the main shaft 32, bringing each successive portion of the surface 64! into contact with the belt 25. At each upward movement of the bandie 56, the stub shaft 52 and rocker arm will be moved longitudinally with respect to the belt 26 either to the right or to the left depending upon the position of the cam groove 12 with respect to the pin 14. (See the position of the stub shaft indicated by the broken lines at 52A in Figure 5.) As a result, the cylindrical surface 64 will be uniformly polished and all surfaces of the belt 26 will be subjected to uniform wear and will not become grooved or distorted. The machine applies a maximum polishing pressure along a line that moves progressively over the surface while at the same time applying a uniformly decreased polishing or bufl'ing pressure on each side of the line of maximum pressure.

While I have described my invention in some detail, I intend this description to be an example only and not as a limitation of my invention, to which I make the following claims:

1. A machine for polishing the cylindrical surface on the valve engaging end of a rocker arm comprising a rotatable shaft, a belt having abrasive material on the outer surface thereof and arranged to run around one end of said shaft,

,a second shaft supported for rotational and longitudinal movement parallel to but eccentric from said first shaft, an arm secured to said second shaft and extending radially therefrom, a stub shaft secured to said arm eccentrically from said second shaft and at a greater distance therefrom than the distance between the axes of said first two shafts, said stub shaft being arranged to rotatably support said rocker arm at a point removed from the center of curvature of the valve engaging surface thereof, and cam means associated with said second shaft operable to move said second shaft longitudinally in response to rotative movement thereof.

2. A machine for polishing the curved valve engaging surface of a rocker arm comprising a first shaft, a second shaft parallel to said first shaft, the axes of said shafts being spaced by a distance slightly'greater than the sum of the radius of curvature of said valve engaging surface and the radius of said first shaft, an abrasive belt arranged to run around one of said shafts, an arm carried by the other of said shafts, means carried by said arm for rotatably supporting said rocker arm upon an axis offset from and parallel to said shafts, the distance between said offset axis and the axis of said other shaft being approximately equal to the distance between said offset axis and the center of curvature of said valve engaging surface, and means for moving said arm and said other shaft longitudinally along the axis of said other shaft.

3. A machine for polishing the cylindrical valve engaging surface of a rocker arm having an aperture formed therein along an axis parallel to but spaced from the axis of said surface, comprising a, rotatable shaft, an abrasive belt arranged to run about said shaft, a second shaft mounted for rotational and longitudinal movement about an axis parallel to but spaced from the axis of said first shaft by a distance approximately equal to the sum of the radius of curvature of said cylindrical surface on said rockerarm and the radius of said rotatable shaft, an arm secured to said other shaft, a stub shaft carried by said arm parallel to the ams of said other shaft and spaced therefrom by a distance approximately equal to the distance between the center of curvature of said surface and the axis of the aperture in said rocker arm, said stub shaft being arranged to fit within said aperture:

in said rocker arm, and cam means associated with said other shaft and arranged to move said other shaft longitudinally in response to rotative movement of said other shaft in one direction.

4. A machine for polishing the cylindrical valve engaging surface of a rocker arm comprising a first shaft, a belt of abrasive material arranged to run around said first shaft, a second shaft mounted for rotation about an axis parallel to but spaced from the axis of said first shaft, the distance between the axes of said shafts being approximately equal to the sum of the radius of curvature of said surface plus the radius of said first shaft plus the thickness of said belt, and means carried by said second shaft for rotatably supporting said rocker arm about another axis spaced from the axis of said second shaft by a distance approximately equal to the distance between the center of curvature of said surface and the axis of rotation of said rocker arm.

5. A machine for polishing an object having a cylindrical surface comprising a pair of spaced parallel shafts, a belt of abrasive material arranged to run over one of said shafts, the distance between the axes of said shafts being approximately equal to the radius of curvature of said surface plus the radius of said one shaft plus the thickness of said belt, and means for rotatably supporting said object eccentrically with respect to the axis of said second shaft by a distance approximately equal to the distance between the center of curvature of said surface and the axis of rotation of said object.

6. A machine for polishing a curved surface on an object comprising a shaft, a belt arranged to run around said shaft, means for ro-tatably supporting said object on said machine and about an axis other than the center of curvature of said surface so that said object may be rotated about said axis to bring said surface into contact with said belt, means for rotating said last mentioned means about another axis approximately coincident with the center of curvature of said surface when said object is in contact with said belt, and means responsive to rotation of said last rotating means for moving said object transversely with respect to said belt.

7; A machine for polishing a curved surface on an object comprising a shaft, a belt arranged to run around said shaft and extending tangentially therefrom, means for rotatably supporting said object on said machine and about an axis other than the center of curvature of said surface so that said object may be rotated to bring said surface into contact with said belt along a line just past the line of tangency between said belt and said shaft, means for rotating said last mentioned means about another axis approximately coincident to the center of curvature of said surface when said object is in contact with said belt, and means responsive to rotation of said last mentioned rotating means for moving said object transversely with respect to said belt.

8. In a polishing machine, a shaft for supporting a Work piece to be polished, an abrasive member, means for rotating said shaft to bring said work piece into contact with said abrasive member, a cam member rotatable about said shaft but fixed against axial movement therealong, ratchet means secured to said shaft and arranged to engage said cam member to rotate said cam member with said shaft in one direction of rotation of said shaft, other ratchet means arranged to engage said cam, means to prevent rotation thereof during rotation of said shaft in another direction, and a fixed member engageable with said cam means to impart axial movement to said cam means and said shaft upon rotation of said cam means.

9. In a machine for polishing an object, a head, a shaft rotatably and axially movable with respect to said head, means for supporting said object On said shaft, an abrasive member positioned adjacent to said last mentioned means whereby said object can be brought into contact with said abrasive member upon rotation of said shaft, means for moving said shaft and object axially comprising a cam member, a follower member, one of said last mentioned members being fixed relative to said head and the other of said last mentioned members being rotatable about said shaft, ratchet means secured to said shaft and engageable with the other of said members for rotating said other member with said shaft during rotation of said shaft in one direction, and other ratchet means engageable with said other member and fixed relative to said head to prevent rotation of said other member upon rotation of said shaft in one direction.

HENRY R. COSTLEY.

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