US2200025A - Grinding machine - Google Patents

Description

May 7, 1940. F. A JONES 2,200,025

GRINDING MACHINE Filed Dec. 15, 1937 2 Sheets-Sheet I.

g gg y dllouuu y 0: F. A. was 2,200,025

GRINDING MACHINE Filed Dec. 15, 1937 2 Sheets-Sheet 2 gwwwp Fraizif fl Jbnes Gum/M Patented May 7, 1940 WENT other I GRINDING MACHINE -Franl-1 A. Jones, Greer, S. 0., assignor of onehalf to'R. G. Hcdgson, Greer, S. C.

Application December. 15, 1937, Serial No. 179,988

11 Claims. (01. 51-430) Myfinvention relates to a grinding machine for grinding the'end of rocker arm'co'mmonly employed for operating valves'in internal combustion engines.

An objeotof my invention is to devisea ma chine for grinding the end of -a rocker arm so that the arm will have rolling contact with the end of the valve stem, thereby avoiding sliding of the arm over the end of the valve stem and in. reducing the consequenttwear and friction. By

my invention, the end of therocker arm is provided with cam-like surface which maintains rolling contact. with the end of the valve stem and causes substantially straight line movement in. of the valve stem, thereby greatly eliminating lateralthrust on the side of the valve stem and preventing excessive Wear between the valve stem and the wall of the valve stem bushing;

While my invention is designed especially for grindingthe e-ndof a rockerarm, it will be obvious that it may be used for grinding other devices than'rocker arms. I

A further object is to" devise a work support for a grindingv machine for grinding a curved: .sn rfaoe fon the work of. relatively large radius. andrwhereinthe work isTotated'zabouta shifting.

instantaneous center of rotationwhich may be relatively close. to the grinding surface.

Two modifications of. my invention are il1ustrated in the accompanying. drawings in whichz' Figure 1 is a plan view of one arrangement of the work-supporting carriage forming my grinding machine;

Figure 2 is a side view of. Figure .1; i v

Figure 3 is an end .view of Figure 1; showing. the work supporting carriage in elevation;

Figures 4, 5 and 6 are kinematic linkage diagrams illustrating the operation of the arrangement shown in Figures 1 to 3;

Figure 7- shows a rocker arm in operative relation .to a valvestem;

Figure 8 is a fragmentary view'showing a modified formfof the invention; and

Figure 9 is a side view of Figure 3.

wheel. 2

Referring to the drawings, the worlr'supportgrinding face of wheel 2, as shown in Figure 1. A lever ii is pivotaily secured by'a pin 4a to the lever 3 near the outer end thereof and is provided with a slotted extension 4b at the free end and arranged at right angles to its main axis and extending over the base I. A stud or pin 5 has a base 5a secured thereto which in turn is adjustably mounted upon lever l as by' means of a pair of screws 5b passing through a slot in the base 5a and having threaded engagement with the lever 4. A pair of collars 5c and 5d havingopposed conical ends are mounted on pin for supporting av rocker arm ti (indicated in dotted lines). It Will be understood that collars 5c and 5d areadjustably secured onto pin 5 by suitable 'r'neans such as set screws. Apair of pins to and 4d are mounted upon lever 4 and arranged to embrace opposite sides ofthe front end of the rocker arm as shownin Figure 1 and hold the rocker arm in position against the radial face of .wheeiZ during grinding operation. Pin id is a resilient pin to hold the rocker arm against pin to but permit the rocker arm to move back in case of too severe contact with the grinding wheell A screw ic forming an adjustable stop limits the movement: of base I towards Mounted upon the base i is a bracket 1 having a longitudinal slot la formed therein; the bracket 1 being arranged in line with the angle exten sion ib on lever 4 or at right angles to the grinding surface. A link 8 is pivotally secured to'extension 4b on lever 4 by means of a pin 8a adjustably secured in the slot of the extension 46-; and' 'link 8 is also pivotally secured to the bracket "4" by'xneans of a pin lb adjustably secured in the slot la by means of a collar To and a nut 103. Link 8 is provided with a' series of holes 8b formed therein to vary the position of pivotal connection on the link.

As shown'in Figure 1, the parts are in their" normal position and the rocker arm 6 is supported on the pin 5 so the face of'the front end to. or the arm is. brought into contact with one radial face of the grinding wheel 2. By swinging thelever 3 by its handle 3a in the direction indicated by arrow A, the lever 3 pivots about the. axis of pin 3b, While the left endof lever 4 is carried with lever 3 due to the pivotal connection of pin 4a. The right end of lever 4' is guided in" its movement by link 8 which is pivotally connected by pin 1b to bracket 1 and also has; pivotal connection at 8a tothe extension 4bon lever; 4. The arrangement is such that as the lever 3 is moved in the direction-A, the

end So of the rocker arm is rotated about an axis somewhere near the axis of pin 31) and at the same time is drawn away from the face of the grinding wheel 2. It will be clear that upon rotating the handle 3 in the direction of the arrow B, a similar movement of the end of the rocker arm will take place.

. fixed pivot point for lever 3, 411 indicates the pivot point for one end of lever t on lever 3, and 7b indicates the fixed pivot point for one end of link 8. The line 5 extending from line 4 represents the rocker arm which is secured to and carried by lever 4.

Figure 4 represents the linkage arrangement in its normal position, and the point 622 indicates the point of contact between the rocker arm and the grinding wheel 2. Since the right end of line 5 tends to rotate about fixed pivot lb, and the left end of line 4 tends to rotate about fixed pivot 3b, the instantaneous center of rotation of the lever 4 is represented by the point 3?) where the center line of link 8 intersects the center line of lever 3.

Figure 5 represents the arrangement where the lever 3 has been moved upward from its normal position. In this condition it will be seen that the original point of contact 6b has moved away from the face of the grinding wheel, and the instantaneous center of rotation of the lever 4 has shifted to the right and is located at the point 4e.

Figure 6 represents the arrangement where the lever 3 has been moved downwardly from its normal position, and under this condition it-will be seen that the original point of contact 61) has also moved away from the face of grinding wheel 2, and the instantaneous center of rotation of the lever 4 has shifted to the left and is, located at the point M. j

Upon an inspection of Figures 4, 5 and 6, it will be seen that the instantaneous center of rotation of the rocker arm shifts substantially parallel to the face of the grinding wheel, and while the center of rotation of the rocker arm is located very close to the face of the grinding wheel 2, nevertheless, due to the shifting of the instantaneous center of rotation, the curvature which is ground on the face of the rocker arm has an effective radius very much greater than the distance from the instantaneous center of rotation to the face of the wheel. It will thus be seen that my invention provides an arrangement by which a curvature of relatively large effective radius may be ground upon a limited surface without interference between other parts. of the Work and the grinding wheel. The desired curvature cannot be ground by using a fixed center of rotation nor by using a great radius of rotation because the edge of the wheel would cut into the web of the rocker arm.

In Figure '7 I have shown a rocker arm in operative relation with the upper end of a valve stem 9. vIn position 3A, the rocker arm is shown in its up iermost position, while at 6B the arm is shown in its mid-position, and at BC the arm is shown in its lowermost position. In order to produce rolling contact between the face of the rocker arm and the upper surface of the valve stem, it is desirable that the point of contact progress sub-' 4 stantially uniformly from a point onthe edgeof the valve stem nearest the center of oscillation of the rocker arm to a point on the opposite side of the valve stem. The line to represents the path of travel of the point of contact between the rocker arm and the upper end of the valve stemf and it will be seen that the contact shifts from left to right as the rocker arm is moved from its upper position to its lowermost position. Stated another way, the point of contact shifts to the left when the valve is raised from its mid-position and shifts to the right when the valve is depressed commodated by adjusting the position of the.

supporting pin 5 along the length of lever 4. The

position of the fixed p-ivot'lb for the link 8 may be adjusted by shifting the pivot in the slot Ia formed in bracket I, and the length of the link 8 may be adjusted by shifting the connection to different holes 8b formed in the link, and alsoby shifting the pivot 3a in the slot formed in extension 4b. It will be understood that instead of using a series of separate holes 8b in link- 8, an elongated slot may be formed in this link.

In Figures 8 and 9 I have shown a modified arrangement for guiding the'right-hand end of the lever 4. In this arrangement the lever 3 is pivots ed to the base I on pin3b asin Figure 1, and the lever 4 is likewise pivoted to the lever 3 in the same manner as in Figure 1, but not shown'in Figure 8 due to the fragmentary showing of thesev two levers. A gear Wheel I0 is securely mounted upon the pin 32) which is journaled in-base I and turns with the lever 3, whereby the gear wheel I0 rotates with the lever 3. A second gear wheel I I is mounted upon a shaft I la which is journaled in base plate I and extends through to the 0pposite side of the plate, gear II is arranged to mesh with gear Ifland is driven by gear Ill. The opposite end of the gear shaft I la has a key-like connection with the slot in a lever I2 which isadjustably secured to the end of shaft IIaby a nut I Iband rotates with gear II., A link I3 joints the lever I2 to the free end of lever 4 by means of pivot I2a carried by the arm I2 and the pivot I3a joining the other end of link I3 to lever 4. The pivot 12a is adjustable in theslot I3b in link I3. It will be understood that lever 4 carries pins like 5, 4c and 4d of Figure 1 for supporting a rocker arm.

The arrangement shown in Figures 3 operate generally in the same manner as the and 9 will' arrangement shown in Figures 1 to 3, in that movement of the arm 3 from its normal position in either direction will cause a rotation of the arm I2 from its normal position, and, through the action of link I3 will move the free end of the lever 4 away from the face of the grinding wheel. In other words, the arrangement is such that the rocker arm carried by the lever 4 will rotate about aninstantaneous center which shifts along: a path substantially parallel with the grindingface of the grinding wheel While my invention has-been shown and described: as particularly suited for grinding the working surface on a rocker arm, it will be understood that it maybe used for grinding other articlesif desired. Variousmodifications will be obvious-to those skilled in the art, andrny invention is restricted only. in accordance with the terms .of itheappended claims. l

What I. claimis: 1. In combination, a grinding. element having afiat grinding surface, a work carriage comprisingv asupporting base arranged for sliding movement inv a-direction. substantially at rightangles torsaidwgrinding surface, a lever pivoted to said sliding base and normally extending substantially parallel to said grinding surface, but being swingableuto. either side of saidnormal position, a link pivoted to said sliding base and normally arranged at right angles to said lever and extending. towards the pivotal axis of. said lever, a second lever pivotally supported atone end upon the first lever at a point removed from its. pivotal axis, means for guiding the free end of said second' lever in a. curved pathcomprising a connection: between the free end of said second lever and said link at a point thereon removed from its pivotal axis, and means carried by said second lever. for supporting a work-piece in contact with .said grinding surface.

, lever at a point removed from. its pivotal axis, said second lever being normally arranged so the free end thereof lies adjacent the pivot point of the first lever, a lateral extension on the free end of said second lever arranged in line with said link and having a longitudinal slot formed therein, adjustable pivot means mounted in said slot for pivotally connecting the free end of the second lever to the free end of said link, and means carried by said second lever for supporting a workpiece in contact with said grinding surface.

3. In combination, a grinding element having a fiat grinding surface, a work carriage comprising a supporting base arranged for sliding movement in a direction substantially at right angles to said grinding surface, a lever pivoted to said sliding base, a gear secured to said lever and arranged to rotate about the pivotal axis thereof, a second lever pivoted to said sliding base, a gear secured to said second lever and arranged to rotate about the pivotal axis thereof, said second gear having meshing engagement with the first gear whereby the second lever is driven by the first lever, a third lever pivotally secured at one end to said first lever, a link element pivotally secured at one end to said second lever and having its free end pivotally connected to'the free end of the third lever, and means carried by said third lever for supporting a work-piece in contact with said grinding surface.

4. A work support for a grinding machine compivoted tosaid base, a gear secured to said second lever and arranged to rotate about the pivotal axisthereof, said second gear having meshing engagement withthe first gear whereby the second lever is driven by the first lever, a third lever pivotally secured at one end to said first lever, a

link element pivotally secured at one end to said second lever and having its free end pivotally connected to the free end of the third lever, and

meanscarried by said third lever for supporting a. work piece.

5. In a machinefor grinding rocker arms, the combination of a grinding element having-a flat grinding surface, a work carriage comprising a supporting base, a lever pivoted to said base on an axis parallel with said grinding surface, said lever normally extending substantially parallel to said grinding surface but being swingable to either side of said normal position, a link pivoted toasaid base and normally arranged. at right angles to said lever. and extending towards the prising in combination-a work carriage comprispivotal axis of the lever, the pivotal axes of said lever and said link being located in a plane sub-" stantially at right angles to said grinding surface,

a second lever pivotally supported at one. end:

uponthe first lever at a point removed from its pivotal axis, a connection between the free end of said second lever and said link at apoint thereon removed from its pivotal axis, a pin supported upon said second lever at a point removed from the pivotal points thereof, and means for sup porting a rocker arm on said pin with the face of the rocker arm in position to engage said grinding surface.

6. In combination, a grinding element having a fiat grinding surface, a work carriage comprising a supporting base, a lever pivoted to said base and normally extending substantially parallel to said grinding surface, a link pivoted to said base and normally arranged at right angles to said lever and extending towards the pivotal axis of said lever, a second lever pivotally supported at one end upon the first lever at a point removed from its pivotal axis, said second lever being normally arranged so the free end thereof lies adjacent the pivot point of the first lever, a lateral extension 'on the free end of said second lever arranged in line with said link and having a longitudinal slot formed therein, adjustable pivot means mounted in said slot for pivotally connecting the free end of the second lever to the free end of said link, and means carried by said second lever for supporting a work-piece in contact With said grinding surface.

7. In combination, a grinding element having a fiat grinding surface, a work supporting base, a lever pivoted to said base on an axis parallel to said grinding surface and located near the plane of said grinding surface, a second lever pivoted to said base on an axis parallel to the pivotal axis of the first lever and arranged at right angles to said grinding surface with respect the pivotal points thereof and in a positionto engage said grinding surface.

, 8. In combination, a grinding element having a fiat grinding surface, a work carriage comprising a supporting base arranged for sliding movement in a direction at substantially right angles to said grinding surface, a lever pivoted to said sliding base on an axis parallel to said grinding surface, said lever being normally arranged substantially parallel to said grinding surface but being swingable to either side of said normal positin, a second lever pivoted at one end to said first lever at a point removed from its pivotal axis, means carried by the second lever for supporting a work-piece in contact with the grinding surface, and means for guiding the free end of said second lever whereby the work-piece is drawn away from the grinding surface when said first lever is moved in either direction from said normal position.

9. A work support for a grinding machine comprising in combination, a base, a lever pivoted to said base, said lever having a normal position but being swingable to either side of said position, a second lever pivotally supported at one end to said first lever at a point removed from the pivotal axis of the first lever, the free end of said second lever normally extending back towards the pivotal axis of the first lever, a link element pivotally secured to said base at a point substantially at right angles to the first lever from its pivotal axis, and a pivotal connection between the free end of said link and the free end of said second lever, and means carried by said second lever for supporting a work-piece.

10. In combination, a grinding element having a fiat grinding surface, a work carriage comprising a supporting base, a lever pivoted to said base and normally extending substantially parallel to said grinding surface, but being swingable to either side of said normal position, a link pivguiding the free end of said second lever in a curved path comprising a connection between the free end of said second lever and said link at a point thereon removed from its pivotal axis, and

means carried by said second lever for supporting.

a work-piece in contact with said grinding sur-' face.

11. In cdmbination, a grinding element having a flat grinding surface, a work carriage comprising a supporting base, a lever pivoted to said base on an axis parallel to said grinding surface, said lever being normally arranged substantially parallel to said grinding surface but being swingable to either side of said normal position, a second lever pivoted at one end to said first lever at a point removed from its pivotal axis, means carried by the second lever for supporting a workpiece in contact with the grinding surface, and

means for guiding the free end of said second lever whereby the work-piece is drawn away from the grinding surface when said first lever is moved in either direction from said normal position.

FRANK A. JONES.

Images