US2732668A

US2732668A - olsson

Info

Publication number: US2732668A
Authority: US
Publication date: 1956-01-31
Anticipated expiration: 1973-01-31

Description

Jan. 31, 1956 o. J. E. OLSSON METHOD AND MEANS FOR GRINDING CAMS 6 Sheets-Sheet 1 Filed Aug. 11. 1952 ,w antriav INVENTOR. ULOV J-E. OLSSON BY $1 Fig.9

Fig. 8

ATTORNEY 0. J. E. OLSSON METHOD AND MEANS FOR GRINDING CAMS Jan. 31, 1956 6 Sheets-Sheet 2 Filed Aug. 11. 1952 JNVENTOR. OLOV :15. UL SSON A T TORNE Y Jan. 31, 1956 o. J. E. OLSSON METHOD AND MEANS FOR GRINDING CAMS 6 Sheets-Sheet 3 Filed Aqg. 11, 1952 and Ki wk g INVENTOR. OLOV J. E. OLSSON ATTORNEY Jan. 31, 1956 o. J. E. OLSSON METHOD AND MEANS FOR GRINDING CAMS 6 Sheets-Sheet 4 Filed Aug. 11. 1952 Jan. 31, 1956 0. J. E. OLSSON 2,732,668

METHOD AND MEANS FOR GRINDING CAMS Filed Aug. 11, 1952 6 Sheets-Sheet 5 Fig. l0

INVENTOR. OLOV J. E. OLSSON ATTORNEY United States Patent 2,732,668 METHOD AND MEANS FOR GRINDING CAMS 010v J. E. Olsson, Dallas, Tex., assignor to Storm-Vulcan, Inc., Dallas, Tex., a corporation of Minnesota This invention relates to a method and means for grinding cams.

The camshafts of internal combustion engines are provided with two or more sets of cams, the cams of each set being of identical configuration but disposed at different radial angles about the axis of the shaft. One set of cams may operate the exhaust valves and the other set the intake or inlet valves of the engine. After prolonged use, the cams become worn due to frictional contact with thevalve stems or push rods and must be reground or refinished if the engine is to operate efiiciently. It is found that the cams, even after prolonged use and wear, have portions which are undamaged since the valve stems or push rods contact only particular portions of the cams. Each cam is, therefore, worn only along one side or perhaps only along the center and has portions which retain the original configuration or contour of the cam. It is desirable to regrind or refinish the cams to restore their original configurations. The machine for refinishing or regrinding the cams should be relatively simple in structure and operation. To this end it should preferably employ a single master cam for refinishing all the cams of each set, and it should be provided with means for producing the master cam for each set of cams from the undamaged portions of a cam which retains the original configuration of the cam.

Accordingly, one object of the invention is to provide an improved means and method for grinding cams.

Another object of the invention is to provide a means and method for the grinding of a plurality of cams dis- .posed at different radial angles along a shaft.

Still another object of the invention is to provide an improved method for restoring cams to their original configuration.

A further object of the invention is to provide a method and means for forming a master cam from the undamaged portions of a cam and employing the master cam to restore the cam to its originalconfiguration.

A still further objectof the invention is to provide 'a method and means for refinishing a plurality of cams of similar configuration disposed at different radial angles about a shaft by the use of ,a single master cam.

Briefly stated, the new and improved method for refinishing or regrindinga plurality of cams of similar configuration disposed at different radial angles about a shaft comprises forming a master cam having a shape or configuration corresponding to the undamaged portion of one of the cams which retains the original configuration of the cam and then employing the master cam to regrindorrefinish .all of .the cams to restore them to their original configuration. The machine for forming the master cam and regrinding or refinishing the cams of the shaft includes a pivotally mounted cradle which supports .a head stock and a tail stock. The camshaft having the cams which are to be reground is rotatably supported .by the head and tail stocks. A fixed cam engaging member adapted to engage the unworn surfaces of a cam as .the camshaft is revolved is employed to move a cam blank, also mounted on and between the head and tail stocks, toward and away from a grinding wheel in accordance with the original configuration of the cam to form a master cam. The master cam is then mounted on the shaft of the head stock and the cams of the camshaft are reground or refinished by the grinding wheel as the master cam causes the cradle to move pivotally as the camshaft is revolved. An indexing means is provided to rotate the camshaft with respect to the master cam so that cams of similar configuration but disposed at difierent radial angles about the axis of the shaft may be refinished by theme of a single master cam.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention and reference to the accompanying drawings thereof, wherein:

Figure 1 is a perspective view of a machine for regrinding cams, showing a camshaft mounted on the cradle with the machine operative to regrind the cams thereof,

Figure 2 is a fragmentary side view of the machine, with some parts broken away, showing the master cam blanks being ground for regrinding a camshaft mounted on the cradle;

Figure 3 is an end view of the machine showing only the top portion of the machine,

' Figure 4 is an enlarged vertical sectional view showing the manner in which the head stock shaft is mounted,

Figure 5 is a sectional view taken on the line 55 of Figure 4,

Figure 6 is a view taken on the line 66 of Figure 4 but with the indexing means and one'wall of the housing removed,

Figure 7 is a perspective view of one of the locking bars used to clamp the head stock and the tail stock on the cradle,

Figure 8 is a vertical sectional view showing the cam engaging member in operative position engaging a cam of the camshaft for grinding a master cam,

Figure 9 is a plan View of the cam engaging member and its mounting means taken on the line 9-9 of Figure 8,

Figure 10 is a vertical sectional view showing a master cam in operative position,

Figure 11 is a vertical sectional view showing the indexing means and the manner in which the camshaft is supported by the head stock,

Figure '12 is a vertical sectional view showing the master cam blanks mounted on the head stock for grind- 111g,

Figure 13 is an end view of the head stock taken on the line 13-13 of Figure 12, and

Figure 14 is a fragmentary top plan view of the shift lever used for selecting master cams.

Referring now to the drawings, the numeral 20 designates a grinding machine for grinding earns 21 on a camshaft 22 rotatably mounted on and between a work head 23 and a tail stock 24. The work head and tail stock are mounted on a cradle 25 which is mounted on the table 26 of the grinding machine for transverse pivotal movement with respect to the table in order that the camshaft may be moved pivotally and transversely of the table toward and away from the grinding wheel 27. The table 26 is pivoted at its center on a subtable 26a in the customary manner to provide for taper adjustments of the cradle. The sub-table 26a is mounted on ways 28 and 29 .of the base 30 of the machine and is movable longitudinally on the base by means of a hand wheel 31. The mounting of the table 26 is not described in detail since it may be of .any well-known commercial construction. It will be understood that the table may be moved longitudinally on the ways 28 and 29 by rotation of the hand wheel 31 in one direction or the other, and may be pivoted about its center in a horizontal plane by a taper adjustment screw 31a.

The grinding wheel 27 is mounted to be driven in any conventional manner by a motor 32 and is movable transversely on the grinding wheel table 33 by means of the hand wheel 34 and lever 37. The grinding wheel table is movable on the ways 35 and 36 of the base 30 by means of the hand wheel 31 which moves both the tables 26 and 26a on which the cradle is mounted and the grinding wheel table 33, the hand wheel being geared to such tables so that as the tables 26 and 26a carrying the cradle are moved in one direction the grinding wheel table is moved in the opposite direction. There is a lost motion connection between the tables so that the cradle tables are moved a predetermined distance before the grinding wheel table is moved, such as is shown and described in the application of Ray Johnson for patent for Traversing Mechanism for Grinding Machine, Serial No. 584,789, filed March 26, 1945. The mounting of the grinding wheel is not shown in detail as it may be of any well-known commercial construction. It will be apparent that the grinding wheel 27 and the table 26 may be moved longitudinally on the base 30 to position the grinding wheel opposite any one of the earns 21 in order that such cam may be ground by the grinding wheel.

The cradle 25 is pivotally mounted on the table 26 by means of a plurality of upstanding legs 38 provided with pivot bearings 39. Pivot shafts 40 extend through the pivot bearings and through suitable apertures in transversely projecting ear members 41 of the cradle to pivotally secure the cradle 25 to the table 26.

A third transversely projecting ear member 42 of the cradle 25, located adjacent the left end of the cradle in Figure 2, is pivotally attached to the end of a shaft 43 which extends through a suitable aperture in said transversely projecting ear member. (See Figure 4.) A nut 44 on the threaded end of the shaft and a washer 45 cooperate with an annular flange 46 on the shaft to secure the member 42 on the shaft. The pivot shafts 40 and the shaft 43 are axially aligned.

The shaft 43 extends through an aperture in a boss 47 formed on a vertical wall 48 in the head stock housing 49. The shaft is rotatably supported in the boss by a roller bearing assembly 50 whose stationary race 51 is held between an internal annular flange 52 in the aperture of the boss and a retaining ring 53 secured to the boss by a plurality of bolts 54 which extend into threaded bores 55 in the boss. The

movable races

56 and 57 abut a lock nut 57a and the annular flange 46, respectively, and are held in proper position thereby.

A head stock bearing bracket 58 is rigidly secured to the inclined top 59 of the cradle by bolts 60 which extend through suitable aligned apertures 61 in the base portion 62 of the head stock bearing bracket. The base portion of the bracket is provided along one side with a pair of angularly disposed faces 65 and 66 which abut the side 67 and top surface 68, respectively, of the cradle top 59. Each of two substantially channel shaped clamps or locking bars 69 has a perpendicular flange 70 disposed in a longitudinal groove 71 provided on the opposite side of the head stock bearing bracket and an outwardly inclined flange 72 having an inclined face 73 which abuts the inclined side 74 of the cradle top 59. The abutting engagement of the inclined faces 73 of the locking bars and the inclined side of the cradle insures that the adjacent face 64 on the bearing bracket base portion will be drawn downwardly toward the cradle top 59 as the bolts 60, which extend through apertures 69a in the locking bars as well as through the apertures 61, are tightened to draw the locking bars toward the side 74 of the Cradle top.

The head stock bearing bracket 58 is thus rigidly mounted on the cradle 25 so that any transverse movement of the bearing bracket will necessarily result in pivotal movement of the cradle about the axis of the pivot shafts 40 and the shaft 43.

A head stock shaft 75 is rotatably mounted in the bearing bracket 58 by means of ball bearings 76 and 77. The ball bearing 77 is held in place abutting an internal annular shoulder 78 in the bracket by a retaining ring 79 secured to the bearing bracket by bolts 80 engaging in threaded bores 81 in the end of the bearing bracket. The bearing 76 is held in place abutting an internal annular flange or shoulder 82 in the bearing bracket by an annular flange 83 on a pulley 84 rigidly secured on the head stock shaft 75 by a key 84a and slot connection or a set screw or other suitable means. The function of the pulley 84 will be hereinafter described.

Also shown to be mounted on the head stock shaft 75 are a ring nut 85 threaded onto said shaft and a pair of master earns 86 and 87. The ring nut holds the pulley and bearings in place on the shaft and also provides for adjustment of the bearings. Washers 88 are disposed between the ring nut 85 and the master cam 86, between the master cams, and between the master cam 87 and a bolt 89 threaded into a threaded bore 90 in the end of the head stock shaft. A key 91 extending through aligned slots in the master cams and the head stock shaft holds the master cams rigidly on the head stock shaft for rotation therewith.

The pulley 84 is provided with an annular groove 92 in which is received the end of the tubular extension 93 of the bearing bracket which extends through an aperture 94 in the vertical wall or partition 48 of the housing. The groove 92 and the tubular extension 93 cooperate to seal off the bearing 76 and the bore of the bearing bracket.

The pulley 84 and head stock shaft 75 are driven by a pair of V-

belts

95 and 96 which connect the pulley 84 to a pulley 97 rotatably mounted on the shaft 43. The pulley 97 is limited against longitudinal displacement on the shaft 43 by means of a retaining ring 98 having a set screw 98a threaded through the ring and having its inner end disposed in a recess 99 in the shaft. Needle type roller bearings 100 may be disposed between the pulley 97 and the shaft 43 to reduce the friction therebetween. Oil seals or gaskets 101 may be disposed at each end of the central bore 102 of the pulley to seal between the shaft 43 and the pulley and prevent loss of lubricant which may be supplied to the bore through a conventional grease fitting 103.

The pulley 97 is in turn driven by a pulley 104 to which it is connected by a pair of V-belts 105 and 106. The pulley 104 is rotatably mounted on a shaft 107 and is restrained against axial displacement thereon by a retaining ring 108 having a set screw 108a threaded therethrough into a recess 109 provided in the shaft. Needle type roller bearings 110 may be disposed in the central bore 111 of the pulley 104 to reduce the friction between the pulley and the shaft. Oil seals or gaskets 112 may be disposed at each end of the central bore to seal between the shaft 107 and the pulley to prevent loss of lubricant which may be supplied to the bore of the pulley through a conventional grease fitting 113.

The shaft 107 is rigidly and eccentrically formed on a belt tightening member 114 adjustably mounted in a boss 115 formed in the outer wall 116 of the housing 49. The belt tightening member is provided with a plurality of circumferentially spaced slots 117 which are selectively engaged by the lower end 118 of a screw 119 threaded through a suitable bore in the boss 115. The slots 117 are arcuately shaped so that the screw end 118 will contact the bottom surface of the slot and will tend to move the belt tightening member inwardly into the housing as the screw is rotated into a slot, whereby the external annular flange 120 on the outer end of the tightening member is forced into engagement with the outer end of the boss. The flange is provided with a plurality of radially disposed openings 121 which provide'means for receiving a bar whereby the tightening member may be turned about its axis. Thus, the shaft 107 may be moved toward or away from the shaft 43 as the belt tightening member 114 is rotated from a position in which the screw 119 extends into one of the slots 117 to a position in which it extends into another of said slots, due to the eccentric mouning of the shaft on the belt tightening member.

The pulley 104 is in turn driven by a pulley 123, to which it is connected by a V-belt 123a. The pulley 123 is rigidly secured on a shaft 124 by a key 125 and slot connection, or in any other suitable manner, as by a set screw. The shaft 124 is rotatably mounted in an eccentric bearing member 126 having a bore 127 disposed off center with respect to an external annular flange 126a on the outer end of the eccentric bearing member. The shaft 124 extends axially through the eccentric bore 127 and is rotatably supported therein by ball bearings 129 which are confined between an internal annular flange 128 at the inner end of the bore and a retaining ring 130 secured to the outer end of the eccentric bearing member by bolts 131 threaded into holes in the outer end of said bearing member. A spacer sleeve 132 spaces the bearings longitudinally of the shaft.

The eccentric bearing member extends through the central bore 133 of a boss 134 of the outer end wall 116 of the housing and is secured to the wall by bolts 135 which extend through the apertures 136 in the annular flange 126.11 of the bearing member into threaded holes 137 in the boss.

An outer drive pulley 138 is rigidly mounted on the shaft 124 by means of a key 139 and slot connection or by any other suitable means, as by a set screw. A nut 140 on the threaded end 141 of the shaft 124 cooperates with the annular flange 142 on the opposite end of the shaft to hold the pulleys 123 and 138 on the shaft.

The outer drive pulley 138 is connected by a V-belt 143 to a pulley 144 on the drive shaft of a motor 145 mounted on the housing 49. Each of the pulleys 138 and 144 are provided with two complementary grooves of dilferent diameters so that the shaft 124 may be driven at two different speeds depending on which pair of complementary grooves of the pulleys are engaged by the belt 143.

The motor 145 is mounted on a plate 145a hinged at one side to the housing, and is pivotally adjustable by a screw 145b which is threaded through the plate and bears against the housing. It will be apparent that the tension of the belt 143 can be varied by rotation of the screw 145b in one direction or the other. The tension of the belt 143 and also of the belt 123a may also be varied by rotating the eccentric bearing member 126 in the boss 134, after the bolts 135 are unscrewed, either clockwise or counterclockwise, since the bore 127 of the bearing member is off center with respect to the annular flange 126:: of the bearing member. The eccentric bearing member is, of course, secured to the boss in its new adjusted position by the bolts 135.

It will thus be seen that the

pulleys

138, 123, 104, 97 and 84 constitute a speed reducing transmission connecting the drive shaft of the motor to the head stock shaft 75, and that the head stock shaft and the camshaft which is connected to it are rotated by the motor 145. It will also be seen that belt tightening means have been provided for the belts 143, 123a, 105 and 106.

The cradle 25 and the work head 23 which is fixed on the head stock shaft 75 mounted on the cradle are pivoted toward and away from the grinding wheel 27 as the head stock shaft is rotated. Such movement is effected by the engagement of one or the other of the master cams 86 and 87 with the cylindrical peripheral surface 146 of a roller member 147 rotatably mounted on a shaft 148 held in a boss 149 of the wall 48 of the housing 49 by a set screw 150 (Figure 4). The roller member is rotatably mounted on theshaft 148 on roller bearings 151 and is slidably movable longitudinally thereon by a cam shift or selector member 152, to select the master cam with which it is to be engaged.

The cam shift or selector member 152 comprises a cylindrical sleeve 153 which is slidably mounted on a shaft 154 rigidly secured in a boss 155 of the wall 48 by a set screw 156 or in any other suitable manner. The cam selector member also includes a fork 157 which extends perpendicularly from the sleeve 153 and into an annular groove 158 formed on the hub 159 of the roller member 147 so that when the selector member is moved longitudinally on its shaft 154, the roller member 147 is also moved longitudinally on its shaft 148.

The cam selector member is moved to preselected positions on its shaft by a shift handle 161 which rotates a gear 162 in mesh with a gear rack 163 integral with the cylindrical sleeve 1.53 of the cam selector member. The gear 162 is rigidly mounted on a vertical shaft 164 which extends upwardly through a bore in a boss 165 in the upper wall 175 of the housing 49. One end of the shift handle 161 is rigidly secured to the shaft 164 by a set screw 166 and a key 166a and slot connection. The other end of the shift handle is provided with an integral vertical sleeve 167 in which a catch or plunger 168 is slidably mounted. A compression spring 169 disposed between an internal flange 170 in the upper end of the bore of the vertical sleeve and the flange 171 on the plunger biases the plunger downwardly, so that the reduced lower end 173 of the plunger engages in recesses 174 formed in the upper wall of the housing. A cap 172 screwed on the upper end of the plunger and slidable on the vertical sleeve provides for lifting the end of the plunger out of the recesses 174 whereby the shift handle may be swung so that the lower end 173 of the plunger may be positioned in any one of several recesses 174 in the upper wall 175 spaced along an are about the shaft 164 to hold the cam selector fork and thereby the roller member 147 in operative position with respect to any selected one of the master cams.

it will therefore be apparent that if the cylindrical peripheral surface 146 of the roller member 147 is in contact with the master cam 86, clockwise movement of the shift handle 161, from a position in which the plunger 16% engages in one recess 174 to a position in which it engages the next recess, will cause the gear 162 to rotate and, since it is in mesh with the gear rack 163, to move the cam selector member 152 to the left, Figure 4, on its shaft 154. The roller member 147 will also be moved to the left by the fork 157 so that the cylindrical peripheral surface 146 will be in contact with the next master cam 87. The recesses 174 are so spaced that when the plunger engages in one of the recesses, the roller member will be aligned with and in position for operative engagement with a predetermined master cam. Likewise, the roller member may be shifted to a position in which it does not engage any master cam.

The head stock bearing bracket 58 and the master cams are biased toward the cylindrical peripheral surface 146 by a compression spring 176, one of whose ends bears against an upstanding lug 177 on the head stock bearing bracket and is disposed about a nipple 178 extending perpendicularly from said lug. The other end of the spring is disposed about a prong or long nipple 179 and bears against a flange 180 on a threaded rod 181 which extends through a threaded bore in the housing 49. Rotation of the threaded rod moves the flange 180 to increase or decrease the force exerted by the spring 176 against the lug 177 of the bearing bracket. A lock nut 182 on the threaded rod is employed to secure the threaded rod in any adjusted position.

It will be seen that the head stock bearing bracket is biased toward the left, Figure 5, to yieldingly press the master cam 86 against the cylindrical peripheral surface 146. As the head stock shaft 75 is rotated, the noncircular configuration of the master cam 86 will cause the head stock bearing bracket and the cradle 25 to which it is connected to pivot about the axis of the shaft 43 and the pivot shafts 40. The camshaft 22 mounted on the cradle by means of the work head 23 and the tail stock 24 will therefore move toward and away from the grindstone, as the head stock shaft 75 is rotated, in a manner determined by the configuration of the master cam.

The head stock bearing bracket may be moved to the left, Figure 6, to move the master cams and into a position in which they cannot engage the cylindrical peripheral surface 146. This is done by means of a hand wheel 183 on the end of a shaft 184 rotatably journaled in a boss 184a of the housing 49. The shaft 184 has a threaded end portion which is received in the threaded bore of a sleeve 185 whose tapered enlarged end 186 is adapted to extend into a recess in a flange 187 on the bearing bracket and to bear against the flange. The sleeve 185 extends slidably through a bore in a boss 185 of the housing 49 and is held against rotation by a key 189 secured to the sleeve by screws 189a. The key is disposed in a suitable slot in the boss, and is slidable in said slot as the screw is rotated by the hand wheel to move said sleeve.

It will thus be seen that when the hand wheel is rotated the threaded portion of the shaft 184 also rotates, causing the sleeve to move longitudinally in one direction or another on the shaft since the key 189 prevents the sleeve from rotating. If the hand wheel is rotated counterclockwise, Figure 2, the sleeve will move to the left, Figure 6, and its enlarged tapered end will engage the flange 187, further counterclockwise rotation causing the head stock bearing bracket to be pivoted to the left against the resistance of the spring 176. The bearing bracket may thus be pivoted to move and hold the master cams out of engagement with the roller member 147. This is desirable if a circular surface, such as a bearing, is to be ground on the camshaft. In addition, the shifting of the circular roller member from one position to another is facilitated if the bearing bracket is moved to disengage the master cams from the roller member.

The camshaft 22 may have a set of cams 21 of identical configuration but which are radially spaced in a predetermined manner about the longitudinal axis of the camshaft. Thus, if a single master cam, e. g., the master cam 86, is to be employed to form or refinish a set of the earns 21, the camshaft must be rotated through a predetermined angle or number of degrees after a particular cam is formed or refinished in order to properly align the next cam of the set with the master cam 36 for refinishing. The manner in which the camshaft is mounted so that it may be so rotated will now be described.

The camshaft 22 is normally rotatably supported at the work head on a spindle or center 190 whose tapered shank 191 extends into a tapered spindle receiving cavity or socket 192 in the end of the head stock shaft 75. The outer end face of the head stock shaft has a slot 193 formed therein transversely of the taper socket 192 in said shaft for a purpose which will be hereinafter described. A fixed plate 194 is rigidly and-non-rotatably mounted on the head stock shaft by a key 195 and slot connection. A set screw 196 threaded in a bore in the fixed plate engages the beveled surface 196:: of a recess in the shaft 75 to hold the plate fixed on said shaft. A lock sleeve 197 threaded on the outer end 198 of the shaft has an inner annular face 199 which abuts either or both an annular flange or abutment 200 on the shaft 75 and an annular flange or abutment 201 on the fixed plate to hold the fixed plate securely against the annular shoulder or abutment 202 on the shaft. The screw 196 engaging the wedge or beveled surface 196a on the shaft also tends to force the plate 194 tightly against the shoulder or flange 202 on said shaft. Thus, the opposite sides of the fixed plate are held between the shoulder 202 of the shaft and the annular face 199 of the lock sleeve so that axial movement of the fixed plate on the shaft is prevented.

A rotatable or indexing plate 204 is mounted on the lock sleeve and has a cylindrical projection or neck 205 which extends into an enlarged portion 206 of the central bore of the fixed plate to abut the annular flange or abutment 201 of the fixed plate. An annular external flange 207 on the outer end of the lock sleeve 197 engages an internal annular shoulder or abutment 209 in the bore of the indexing plate. The indexing plate is thus held against axial movement on the locking sleeve by the flange 207 and the annular abutment 201 of the fixed plate, but may be rotated on said lock sleeve. Recesses 210 are provided in the lock sleeve to allow a rod or spanner wrench to be inserted therein to unscrew or screw the lock sleeve on the shaft '75.

The rotatable or indexing plate 204 is provided with a plurality of indexing apertures 211 in its inner side which abuts the outer side of the fixed plate. These indexing apertures are spaced at predetermined intervals so that the indexing plate may be rotated through predetermined angles relative to the fixed plate. A plunger 212 slidably mounted in a bore 213 in the fixed plate has a reduced end or pin 214 which enters the apertures 211 to lock the rotatable plate against rotation with respect to the fixed plate. A set screw 215 threaded through the plunger has its lower end engageable in recesses 216 provided in the bore 213 in which the plunger is mounted, so that the set screw may be unscrewed to free the plunger for movement away from the rotatable indexing plate. When the pin end of the plunger is moved away from the indexing plate the rotatable indexing plate may be rotated on the lock sleeve. After the rotatable indexing plate has been rotated a predetermined number of degrees to a new position, the reduced end of the plunger is inserted in another aperture 211 in the indexing plate and the set screw is then rotated to lock the plunger in place. The indexing apertures may be provided at equally spaced angular intervals in the indexing plate to provide four, six, eight, twelve, sixteen or other positions for the indexing plate.

A face plate 218 is rigidly secured to the rotatable indexing plate by a plurality of bolts 219 which extend through the face plate into the threaded bores 220 in the rotatable plate. The face plate is provided with a removable drive bar 221 having its inner end disposed in an eccentric bore in the face plate parallel to the axis of the shaft 75 and held securely in place therein by means of a set screw 2210. The outer end of the drive bar is formed with flats 222 and extends between the

legs

223 and 224 of a disk 225 which is rigidly secured to the end of the camshaft 22 by a key 225a and slot connection. A set screw 226 may be provided in each of the lugs to hold the flat portion 222 of the drive bar in position between the legs, and to provide for fine adjustments of angular displacement of the camshaft about its longitudinal axis, if necessary or desirable. The camshaft supported on the centers and 243 of the work head and tail stock will thus be rotated with the master cams 86 and 87 which are rigidly secured on said head stock shaft.

The apertures 211 in the rotatable plate 204 are preferably spaced in a predetermined manner to enable each set of cams of the camshafts of four, six, eight, twelve or sixteen cylinder internal combustion engines to be formed or refinished by the use of a single master cam. For example, each cam of the set of cams which operates the exhaust valves of a six cylinder engine is of the same configuration as the other five exhaust carns, but is disposed around the axis of the shaft in a particular angular position with respect to the other five cams. A single master cam, such as the master cam 86, may therefore be employed to form or refinish all the cams which operate the exhaust valves, since six of the apertures 211 in the rotatsmas es able indexing plate 204 are spaced in a manner that gorresponds to the angular positioning of the exhaust valve cams. Rotation of the indexing plate with respect to the fixed plate 194, and therefore with respect to the master cam 86, to the positions predetermined by the location of these six apertures 211 will permit the master cam 86 to be used to form or refinish all six of the exhaust valve cams. It will be understood, of course, that the grinding wheel 27 must be aligned with the particular cam which is to be formed or refinished each time the rotatable plate is moved from one position to another.

The camshaft of a six cylinder engine will also have six intake cams which operate the intake yalves. The intake valve cams are generally of different configuration than the exhaust valve cams and, therefore, a different master cam, such as the master cam 87, must be used to form or refinish the intake valve cams. Since the number of cams in each case is the same, the same six apertures 211 may be used to refinish the inlet valve cams, provided the master cam 87 is properly positioned with respect to the master cam 86. The particular master cam to be employed is selected by movement of the shaft handle 161. Furthermore, since the master cams are keyed in place on the head stock shaft 75 in proper relationship with respect to each other, as will hereinafter be further explained, at each setting of the indexing plate the intake and exhaust cams for a particular cylinder may both be reground by shifting the roller member 147 into engagement with the proper master cam.

Indicia (not shown) may be provided on the peripheries of the fixed and indexing plates to indicate the particular predetermined position of the rotatable plate with respect to the fixed plate.

In practicing the method of this invention, the master cams 86 and 87 are ground from the undamaged surfaces of cams of a camshaft whose cams are to be refinished. In this case, the drive bar 221 is removed from the face plate and the center 190 is removed from the taper socket 192 of the head stock shaft and a master cam grinding fixture or mount 227 has a shank 228 having opposed flat surfaces 228a which engage the sides of the slot 193 at the outer end of the head stock shaft. A pair or more of master cam blanks 229 and 230 are rigidly and nonrotatably mounted on a shaft or mandrel 231 of the fixture by means of a key 232 and slot connection. A look sleeve 233 on the threaded portion 234 cooperates with a spacer ring 235 and a flange 236 on the mandrel to hold the blanks against axial movement on the mandrel. The lock sleeve may be provided with apertures 233a into which a rod or spanner wrench may be inserted to rotate the lock sleeve.

An auxiliary face plate 238 is mounted on the reduced outer end portion 239 of the mandrel 231 by means of a key 240 and slot connection. The inner end of a set screw 241 threaded in a radial bore in the face plate engages a wedge or beveled surface 242 on such reduced end portion of the mandrel and urges .said face plate into engagement with the lock sleeve 233 to hold the auxiliary face plate against axial displacement on the reduced portion of the mandrel.

The auxiliary face plate is also provided with an eccentric bore 244 into which the end of the drive bar 221 may be inserted, the bar extending parallel to the axis of the mandrel and having its fiat portions 222 received between the

legs

223 and 224 of the drive disk 225 on the camshaft. A set screw 244a is threaded radially of the face plate into the bore 244 to hold the drive bar therein.

The mandrel 231 of the master cam grinding fixture terminates in a center 245 which supports one end of the camshaft, the center 243 of the tail stock supporting the other end of the camshaft.

The master cam blank which is to be ground, say the master cam blank 230, is positioned opposite the, grindstone and is moved toward and away from the grind-, stone by pivotal movement of the cradle 25 which car- 10 ties the head stock-and tail stock. As has already been explained, each cam is generally worn along one side or perhaps along the center by the valve stem or push rod; and, therefore each cam has unworn, undamaged portions which retain the original configuration of the cam. A cam engaging member 246 having hardened follower surfaces 246:; and 24612 of substantial width is carried by a support rigidly mounted on the table 26 of the grinding machine. The follower surfaces of the engaging member engage the unworn portions of the cam least damaged so that the shape of the master cam formed from the master blank 230 will have a configuration which will reproduce or refinish the cams of that set to their original configuration. Of course, the dimensions of the refinished cams will be reduced by such regrinding, but the proportions or configuration of the cams will remain the same as originally.

The cam engaging member 246 is in the form of a rectangular plate having a flat follower surface 246a at one end and a convex curved follower surface 24Gb at its other end, such curved surface being substantially equal to the periphery of the grinding wheel. The rectangular plate is adjustably mounted on a holder 247 by means of bolts 248 which extend through parallel slots 249 in the cam engaging member into threaded bores in the holder. The bolt and slot mounting of the cam engaging member permits it to be adjusted transversely toward and away from the cams of the camshaft.

The holder 247 itself is mounted on a support 251 for longitudinal movement parallel to the camshaft, being slidingly mounted on the way 250 of said support, which is rigidly secured to the table 26 by bolts 252. The holder 247 has inclined lips or

flanges

253 and 254 which telescope on the way 250, and said holder is rigidly secured to the way by bolts 255 threaded through the flange 254 to engage against the side of the Way 256.

In use, when a camshaft with worn cams is to be refinished, the camshaft is mounted on the center 245 of the master cam grinding fixture and the center 243 of the tail stock. If the camshaft has two sets of cams, two cam blanks are mounted on the mandrel of the grinding fixture. If the camshaft has three sets of cams, a third cam blank is added and the spacer ring 235 is removed. The drive bar 221 of the auxiliary face plate is disposed between the

legs

223 and 224 of the disk 225 secured on the end of the camshaft so that the camshaft will rotate with the master cam grinding fixture. The disk is keyed on the camshaft so that the key slot of the camshaft is radially aligned with the opening between the legs of the disk. Thus, the fixed plate 194, the rotatable plate 204, the master cam blanks 229 and 230, and the auxiliary face plate 238 are aligned in a predetermined manner by their key and slot connections with respect to the key slot of the camshaft. For example, as shown in the drawings, the

keys

91, 155, 232, 240 and 225a are all aligned in a straight line so that the master cams made from the cam blanks may be mounted on the shaft 75 by means of the key 91 in the same relative position with the cams of the camshaft as they were mounted on the mandrel of the grinding fixture with respect to said cams while such master cams were being ground.

Thus, the support 251 is mounted on the table 26 and the .cam engaging member 246 is adjusted to a position where it will engage the unworn portions of a cam 21 of one set of cams, say the exhaust valve cams. The hand wheel 183 is then rotated to move the tapered end 186 of the sleeve 185 to the right (Figure 6) to allow the head stock bearing bracket to move pivotally to the right and thus permit the cradle to pivot toward the cam engaging member 246, so that the cam 21 is held yieldingly against the cam engaging member by the spring 176. The grinding wheel 27 is then aligned with the cam blank 11 230 and the

motors

32 and 145 are started by actuation of their

switches

256 and 257, respectively. The head stock shaft 75 will be rotated and, since the master cam grinding fixture 227 is rigidly connected to said head stock shaft, the master cam grinding fixture and the camshaft will also be rotated. The camshaft being yieldingly biased toward the cam engaging member 246 by the spring 176 which bears against the head stock bearing bracket, the cam 21 which engages the cam engaging member will cause the whole cradle 25 and all components mounted thereon to move pivotally and transversely as the cam is rotated against the cam engaging member. As a result, the cam blank 230 is moved toward and away from the grinding wheel as the camshaft is rotated. The grinding wheel is then advanced to contact the cam blank 230 and grind it to a configuration or contour which corresponds to the original configuration of the cam 21. The configuration or contour of the master cam so ground will not, of course, necessarily be identical to that of the cam 21, due to differences in size between the master cam and the cam 21 and the large radius of the grinding wheel, and other factors.

After the cam blank 230 is ground, the grinding wheel is aligned with the cam blank 229 and the cam engaging member 246 is aligned with a cam 21 of another set of cams, say the intake valve cams, so as to contact the unworn surface of such cam. The cam blank 229 is thereupon ground into a master cam having a configuration or contour corresponding to the original configuration or contour of the inlet valve cams.

The master cam grinding fixture is then removed from the head stock, and the newly ground master cams are mounted on the head stock shaft 75 in the manner in which the master cams 86 and 87 are shown to be mounted. A door 259 mounted on a hinge 258 provides access to the interior of the housing 49 for the mounting and removal of the master cams. The center 19%) is mounted in the socket of the work head and the camshaft is mounted on the center 190 and the center 243 of the tail stock. The bar 221 is, of course, connected to the face plate 204 and engaged between the legs 223 and 224- of the drive disk 225 on the camshaft. The alignment of the keys )1, 195 and 225a insures that the master cams will be aligned in the same manner with respect to the cams of the camshaft as the cam blanks were when the master cams were ground.

The roller member 147 is then positioned by means of the shift handle 161 to place the cylindrical peripheral surface 146 in engagement with one of the master cams, the hand wheel 183 being rotated as necessary whenever the head stock bearing bracket must be moved to cause either engagement or disengagement of the cylindrical peripheral surface 146 with a master cam. The grinding wheel is next aligned with one of the cams of a set of cams, say the exhaust valve cams, having the corresponding configuration. The motors are again started and the cam is ground or refinished to its original configuration. It will be evident, of course, that the size of the cam will be somewhat smaller but the configuration will be the same. After one of the exhaust valve cams is refinished, the motors are stopped, the shift lever 161 operated to position the roller member in operative position with respect to the other or intake master cam, after which the grinding wheel is positioned opposite the corresponding intake cam on the camshaft and such intake cam reground or refinished in the same manner as the exhaust cam. After the cams for that particular position or cylinder have been refinished, the motors are stopped, the set screw 215 is unscrewed and the plunger 212 is retracted to permit the indexing plate 204 to be rotated to a position corresponding to the radial position of the next pair of cams. The plunger is advanced to lock the indexing plate to the fixed plate 194, the grinding wheel is moved 12 into alignment with the next exhaust valve cam, and this cam is then refinished.

The shift lever 161 is then moved to move the roller member 147 to place the cylindrical peripheral surface 146 in engagement with the other master cam whose configuration corresponds to that of the intake cams. The intake cam is then refinished in the same manner as was the exhaust cam. This sequence of operation is repeated until all of the valve cams are refinished.

It will be apparent that the camshaft could be provided with more than two sets of cams. In this case, an additional master cam would be provided and ground for each additional set of cams.

It will therefore be seen that a new method and a new means have been provided for making master cams from the unworn surfaces of old cams and employing these master cams for refinishing the old cams. It will also be seen that a single master cam is employed to form or refinish a plurality of cams disposed at different radial angles about a shaft, and that the use of a single master cam is made possible by the provision of an indexing plate 204, to which the camshaft is rigidly connected and which may be rotated to predetermined angular positions with respect to the master cam corresponding to the different radial angles at which the cams are disposed about the shaft.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. In a camshaft grinding machine having a grinding wheel; a longitudinally movable table; a cradle pivotally mounted on said table for transverse movement toward and away from said grinding wheel; a head stock having a spindle and a tail stock for rotatably supporting a camshaft having a plurality of cams to be ground; means for rotating said head stock spindle; means for mounting a master cam blank to be ground into a master cam on said head stock for rotation with said camshaft; a member for engaging unworn surfaces of a cam for imparting a pivotal movement to said cradle as said camshaft is revolved to cause said grinding wheel to grind said cam blank and generate a contour on said cam blank corresponding to the contour of the unworn surfaces of said cam; means for mounting said master cam on said head stock spindle in the same angular position relative to said cam previously held by said master cam blank; and a roller member for engaging said master cam for imparting a pivotal movement to said cradle as said head stock is revolved to generate a contour on said cam as it is ground corresponding to the contour of the unworn surface of-the cam.

2. A camshaft grinding machine for regrinding camshafts having a plurality of angularly offset cams having the same camming contour and having the camming surfaces thereof partly worn, said machine including: a grinding wheel; a longitudinally movable table; a cradle pivotally mounted on said table for transverse movement toward and away from said grinding wheel; a work head having a spindle and a tail stock both mounted on said cradle for rotatably supporting said camshaft; means for rotating said work head spindle; means whereby a master cam blank to be ground into a master cam may be mounted on said work head spindle for rotation with said camshaft; a member on said table for engaging unworn surfaces of one of the cams of said camshaft for imparting a pivotal movement to said cradle with respect to said grinding wheel as said camshaft is revolved whereby said grinding wheel may contact and grind said master cam blank and generate a contour on said master cam blank corresponding to the contour of the unworn surfaces of said cam; means whereby said master cam may be mounted on said work head spindle in the same angular position relative to said cam previously arnyard cam blank;a roller member mounted on a shaft adjacent said work 'spindle adapted for engaging said master cam for imparting a reciprocating pivotal movement to said cradle relative'to said grinding wheel as said work head spindle is revolved whereby said grinding wheel may engage and grind said cam to generate a contour on said cam corresponding to the contour of said unworn surfaces of the cam; and indexing means on said work head spindle whereby said camshaft'may be rotated to and secured in predetermined positions'relative to said master cam corresponding to the angularly offset positions of each of the cams about the axis of said camshaft.

3. A camshaft grinding machine for regrinding camshafts haying a plurality of sets of angularly offset earns, the cam surfaces of each set having the same contours and the surfaces of said cams being partly worn, said machine including: a grinding wheel, a longitudinally movable table; a cradle pivotally mounted on said table for transverse movement toward and away from said grinding wheel; a head stock shaft and a tail stock both mounted on said cradle for rotatably supporting said camshaft; means whereby a plurality of master cam blanks to be ground into master cams may be mounted on said head stock shaft for rotation therewith; a member carried by the table adapted for engaging unworn surfaces of a selected one of the cams of said camshafts for imparting pivotal movement to said cradle toward and from said grinding wheel as said camshaft is revolved whereby said grinding wheel may engage and grind a selected one of said master cam blanks and generate a contour on said selected one master cam blank being ground corresponding to the contour of said unworn surfaces of the selected cam, each of said master cam blanks being ground to a contour corresponding to the contours of a corresponding set of cams; means on the head stock shaft whereby said master cams may be mounted on said head stock in the same angular positions relative to said camshaft previously held by said master cam blanks; a' roller member mounted on a shaft adjacent and parallel to said head stock shaft and adapted for selectively engaging said master cams for imparting a pivotal movement to said cradle with'respect to said grinding wheel whereby said grinding wheel may engage and regrind the contour of said selected cam; and indexing means on said head stock shaft whereby said master cams may be rotated to predetermined positions relative to said camshaft corresponding to the angularly offset positions of the cams of their respective corresponding sets of cams about the axis of said camshaft.

4. A camshaft grinding machine including a transversely movable grinding wheel; a longitudinally movable table; a cradle pivotally mounted on said table for transverse movement toward and away from said grinding wheel; a head stock and a tail stock on said cradle adapted for rotatably supporting a camshaft having a plurality of sets of cams to be ground; cams of each set having similar contours and being ofiset angularly around the axis of the camshaft; a plurality of master cams on said head stock, each of said master cams having a contour corresponding to the contour of the cams of a corresponding set of cams; a roller member mounted adjacent said master cams and adapted for selectively engaging said master cams and imparting a pivotal movement to said cradle relative to said grinding wheel whereby said grinding wheel may engage and grind a predetermined contour on a cam being ground deter mined by the contour of the master cam engaged by said roller member; means on said head stock for rotating said master cams to predetermined positions relative to said camshaft corresponding to the angularly offset positions of the cams of their respective corresponding sets of cams about'the axis of said camshaft; said roller member being rotatably and slidably mounted on a shaft disposed parallel to said "head stock shaft; and means for sliding said roller member on said shaft to any selected position of a plurality of predetermined positions to engage a selected master cam.

5. A cam grinding machine comprising: a grinding wheel; a longitudinally movable table; a cradle pivot ally mounted on said table for movement toward and away from said grinding wheel; a tail stock and a head stock having a spindle on said cradle for rotatably supporting a camshaft having a plurality of cams offset angularly around the axis of the camshaft; said head stock including a head stock shaft; a fixed plate rigidly mounted on said head stock shaft; a rotatable indexing plate mounted on said shaft; means on said fixed plate and indexing plate for selectively rigidly securing said indexing plate to said fixed plate in any one of a plurality of predetermined positions at difierent radial angles about the axis of said head stock shaft corresponding to the angularly offset positions of said cams about the axis of the camshaft; means for rigidly connecting said indexing plate to said camshaft; a plurality of master cams on said head stock shaft; a roller member for selectively engaging said master cams and imparting a pivotal movement to said cradle as said head stock spindle is revolved to generate a contour on the cam being ground determined by the contour of the master cam engaged by said roller member; said roller member being rotatable and slidably mounted on a shaft disposed parallel to said head stock shaft; and means for sliding said roller member to any selected position of a plurality of predetermined positions to engage a selected master cam.

6. A cam grinding machine comprising: a grinding wheel; a longitudinally movable table; a cradle pivotally mounted on said table for movement toward and away from said grinding wheel; a tail stock and a head stock on said cradle for rotatably supporting a camshaft having a plurality of cams offset angularly from each other around the axis of the camshaft; said head stock including a head stock shaft; means for rotating said head stock shaft; a fixed plate rigidly mounted on said head stock shaft; a rotatable indexing plate mounted on said shaft; means on said fixed plate and said indexing plate for selectively rigidly securing said indexing plate to said fixed plate in any one of a plurality of predetermined positions at different radial angles about the axis of said head stock shaft corresponding to the positions of said cams about the axis of the camshaft; means rigidly connecting said indexing plate to said camshaft; means whereby a master cam blank may be mounted on said head stock shaft in alignment with said camshaft for rotation therewith; a follower member on the table adapted for engaging unworn surfaces of a cam on said camshaft as said camshaft is rotated to cause said cradle to reciprocate said master cam blank with respect to said grinding wheel whereby said grinding wheel may engage and grind said master cam blank to generate a contour on said master cam blank determined by the contour of the unworn surfaces of said cam; a roller member mounted on a shaft adjacent said head stock shaft; means whereby the master cam thus formed may be mounted on said head stock shaft in a position to be engaged by said roller member whereby a pivotal movement toward and away from said grinding wheel may be imparted to said cradle as said head stock shaft is rotated whereby said grinding wheel may engage and regrind the contour of the cams of said camshaft to a contour determined by the contour of said master cam and corresponding to the contour of the unworn surfaces of the original cam.

7. The method of refinishing a cam having portions of the camming surface damaged and other portions undamaged comprising: moving a master cam blank relatively toward and away from a grinding wheel in accordance with the undamaged portions of the camming surface of said cam, said undamaged portions of said camming surface controlling the movement of the master cam blank toward and away from said grinding wheel; contacting said master cam blank with the grinding wheel whereby said grinding wheel grinds said master cam blank to form a master cam having a contour corresponding to the contour of the undamaged surfaces of the cam; then bringing the camming surface of the cam into grinding contact with said grinding wheel and moving said cam toward and away from said grinding wheel in accordance with the configuration of the master cam previously ground from the undamaged portions of the camming surface of said cam; and grinding the camming surface of said cam to remove the damaged portions of said surface.

8. The method of refinishing a set of cams on a camshaft, said cams all having the same configuration but being disposed at different radial angles about the axis of said camshaft, said cams having portions of their camming surfaces damaged and other portions undamaged, which method comprises: moving a master cam blank relatively toward and away from a grinding wheel in accordance with the undamaged portions of the camming surface of one of said cams, said undamaged portions of said camming surface controlling the movement of the master cam blank toward and away from said grinding wheel; contacting said master cam blank with the grinding wheel whereby said grinding wheel grinds said master cam blank to form a master cam having a contour corresponding to the contour of the undamaged surfaces of said cam; then bringing the camming surface of the cam into grinding contact with said grinding wheel and moving said cam toward and away from said grinding wheel in accordance with the configuration of the master cam previously ground from the undamaged portions of the camming surface of said cam; grinding the camming surface of said cam to remove the damaged portions of said surface; indexing each of said cams angularly about the axis of the shaft to a proper position with respect to said master cam to be ground; and grinding each cam surface so positioned.

9. The method of refinishing a plurality of sets of cams of different configurations disposed at different radial angles about the axis of a shaft, said cams having portions of their camming surfaces damaged and other portions undamaged, which method comprises: moving a master cam blank relatively toward and away from a grinding wheel in accordance with the undamaged portions of the camming surface of a selected cam of one of the sets, said undamaged portions of said camming surface controlling the movement of the master cam blank toward and away from said grinding wheel; contacting said master cam blank with the grinding wheel whereby said grinding wheel grinds said master cam blank to form a master cam having a contour corresponding to the contour of the undamaged surfaces of said selected cam; then bringing the camming surface of said selected cam into grinding contact with said grinding wheel and moving said selected cam toward and away from said grinding wheel in accordance with the configuration of the master cam previously ground from the undamaged portion of the camming surface of said selected cam; and grinding the camming surface of said cam to remove the damaged portions of said surface; rotating said camshaft a predetermined degree corresponding to the different radial angles of each of the cams of said selected set about the axis of said camshaft after each said selected cam is refinished to position a successive cam in proper position with respect to said master cam and said grinding wheel for regrinding the camming surface of said cam; and repeating the operations of grinding a master cam and then grinding the camming surfaces of the cams of each successive set of cams.

10. The method of refinishing a cam having portions 0f the camming surface damaged and other portions undamaged comprising: mounting the cam and a master cam blank in longitudinal axial alignment with each other for rotation about their common axes; controlling relative movement of the master cam blank with respect to a grinding wheel by rotation of the blank and the cam about their axes with the undamaged camming surface of the cam in engagement with a non-shifting follower means; grinding the master cam blank to form a master cam having a contour corresponding to the contour of the undamaged surface of the cam; then controlling relative movement of the cam with respect to said grinding wheel by rotation of the cam and the master carn thus formed with the master cam in engagement with a second follower; and with said grinding wheel contacting and regrinding the camming surface of the cam to remove the damaged portions of said surface.

11. The method of refinishing the camming surfaces of a camshaft having a plurality of cams thereon each angularly offset with respect to the other cams, and said cams having portions of their camming surfaces damaged and other portions undamaged, which method comprises: mounting the camshaft and a master cam blank in longitudinal axial alignment with each other for rotation about their common axes; controlling relative movement of the master cam blank toward and away from a grinding wheel by rotating the blank and the camshaft upon their axes with the undamaged camming surfaces of a selected one of the cams of said camshaft in engagement with a non-shifting follower means; grinding the master cam blank to form a master cam having a contour corresponding to the contour of the undamaged surface of said selected cam; then contacing said one of the cams with the grinding wheel and controlling relative movement of the cam toward and away from said grinding wheel by rotation of the cam and the master cam previously formed with the master cam in engagement with a second follower; regrinding the camming surface of said cam to remove the damaged portion of said surface; and successively rotating said camshaft to predetermined angularly displaced positions relative to said master cam corresponding to the angularly offset position of successive ones of the cams on said camshaft about the axis of said camshaft to successively position such successive ones of said cams on said camshaft in contact with said grinding wheel; and successively grinding each of said other cam surfaces to remove the damaged portions of said surfaces.

12. The method of refinishing a camshaft having a plurality of sets of angularly offset cams thereon, said cams having portions of their camming surface damaged and other portions undamaged, said method comprising: mounting the camshaft and a plurality of master cam blanks corresponding in number to the number of sets of cams on said camshaft in longitudinal axial alignment with each other for rotation about their common longitudinal axes; contacting a first one of the master cam blan s with a grinding wheel; controlling relative movement of the selected master cam blank toward and away from said grinding wheel by rotation of the master cam blanks and camshaft about their axes with the undamaged camming surface of one of the cams of a first one of the sets of cams in engagement with a non-shifting follower means; grinding said first master cam blank to form a first master cam having a contour corresponding to the contour of the undamaged surface of said one of the cams of said first set of cams; positioning a second master cam blank in contact with said grinding wheel; controlling relative movement of said second master cam blank toward and away from said grinding wheel by rotating said master cam blanks and the camshaft about their axes with the undamaged camming surface of one of the cams of a second set of cams in engagement with a non-shifting follower means; grinding the second master cam blank to form a second master cam having a contour corresponding to the contour of the undamaged surface of said one of the cams of said second set of cams; repeating the shifting and grinding operations to correspond to the number of sets of cams and the number of master cam blanks to form a master cam for each set of cams on said camshaft; positioning said grinding wheel in po sition to contact one of the cams of said first set of cams; controlling relative movement of said one of the cams of said first set of cams with respect to said grinding wheel by rotation of the camshaft and the first master cam about their longitudinal axis with said first master cam in engagement with a second follower; regrinding the camming surface of said one of the cams of said first set of cams to remove the damaged portions of said surface; rotating said camshaft on its longitudinal axis with respect to said first master cam to a predetermined position relative to said master cam corresponding to the angularly offset position of each of the cams of said first set of cams, and successively grinding the camming surface of each cam of said first set of cams to remove the damaged portions of said surfaces; shifting the second follower to engage the second master cam and shifting the grinding wheel to engage one of the cams of the second set of cams on said camshaft; controlling relative movement of said one of the cams of said second set of cams with respect to said grinding wheel by rotation of the camshaft and the second master cam on their longitudinal axis with the second master cam in engagement with the second follower; regrinding the camming surface of said one cam of said second set of cams to remove the damaged portions of said surface; rotating said camshaft to predetermined positions relative to said second master cam corresponding to the angularly offset positions of each cam of said second set of cams about the axis of said camshaft, and successively grinding the camming surfaces of each of said second set of cams; and repeating the operations for each additional set of cams and for each additional master cam.

13. A camshaft grinding machine for regrinding camshafts having cams with partly worn areas on the camming surface thereof, said machine including: a grinding wheel; a longitudinally movable table; a cradle pivotally mounted on said table for transverse movement toward and away from said grinding wheel; a work head having a spindle and a tail stock both mounted on said cradle for rotatably supporting said camshaft having a cam to be reground; means for rotating said work head spindle; means whereby a master cam blank to be ground into a master cam may be mounted on said work head spindle for rotation with said camshaft; a member on said table for engaging unworn surfaces of one of the cams of said shaft for imparting a pivotal movement to said cradle as said camshaft is revolved to cause said grinding wheel to grind said cam blank and generate a contour on said cam blank corresponding to the contour of the unworn surfaces of said cams; means whereby said master cam may be mounted on said work head spindle in the same angular position relative to said cam previously held by said master cam blank; and a roller member mounted on a shaft adjacent said work head spindle for engaging said master cam when so mounted on the work head spindle for imparting a reciprocating pivotal movement of said cradle with respect to said grinding Wheel as said work head spindle is revolved whereby said grinding wheel may engage and grind said cam to generate a contour on said cam corresponding to the contour of the unworn surface of the cam.

14. A device of the character set forth in claim 13 including: mean adjustably yieldably biasing said work head spindle toward said roller member.

15. A device of the character set forth in claim 2 including: means adjustably yieldably biasing said work head spindle toward said roller member.

16. A device of the character set forth in claim 3 including: means adjustably yieldably biasing said head stock shaft toward said roller member.

17. A device of the character set forth in claim 3 wherein: the roller member is slidable on its shaft, and means is provided for adjusting the position of said roller member on its shaft, whereby said roller may be selectively'engaged with any one of said plurality of master cam blanks which may be carried by said head stock shaft References Cited in the file of this patent UNITED STATES PATENTS 535,127 Balzer Mar. 5, 1895 1,000,516 Hanson et al Aug. 15, 1911 1,156,323 Shearer Oct. 12, 1915 1,791,479 Silven Feb. 3, 1931 1,922,520 Bath Aug. 15, 1933 2,557,043 Wright et al June 12, 1951 2,561,981 Green July 24, 1951 2,641,874 Kirby June 16, 1953 FOREIGN PATENTS 236,959 Great Britain Sept. 9, 1926 518,923 Great Britain Mar. 12, 1940