US2334938A - Cam grinding machine - Google Patents

Description

c. w. LANG 2,334,938

CAM GRINDING MACHINE Nov. 23, 1943.

Filed Ma rch 29, 1945 2 Sheets-Sheet 1 INVENTOR. ARLES WLmva 147' TORNEY Nov; 23, 1943. v c. w. LANG 2,334,938

CAM GRINDING MACHINE Filed March 29, 1945 2 Sheets-Sheet 2 INVENTORj V CHARLEJ W Ln/vs ATTOQNEY Patented Nov. 23, 1943 CAM GRINDING MACHINE Charles W. Lang, San Francisco, Calif., assignor to Enterprise Engine & Foundry Company, San Francisco, Calif., a corporation of California Application March 29, 1943, Serial No. 480,923

7 Claims.

This invention relates to machines for making duplicate cams by the grinding process from cast or roughly formed blanks, under the control of a master or template cam, on the general principle of a duplicating lathe, and the object of the invention is to provide improvements in such a machine whereby it takes the form of a very compact machine adapted for grinding rim cams.

Other objects and features of the machine will appear in the following description and accompanying drawings.

In the drawings:

Fig. 1 is a perspective view of my improved cam grinding machine with master cam and the duplicate cam being ground, shown in place.

Fig. 2 is a plan view of the machine with the work shaft driving gear assemblage omitted.

Fig. 3 is a vertical cross section of the machine taken along the line 33 of Fig. 2.

Fig. 4 is a vertical end elevation of the machine taken from the right-hand end of Fig. 2.

Fig. 5 is a perspective view showing the grinding wheel dresser in position.

Briefly described the machine comprises two spaced parallel shafts I and. 2, rotatably mounted on a supporting base 3, one shaft carrying the master or template cam 4 at one end and the blank or cam 5 to be ground, at the other end. Shaft l is the grinding wheel motor shaft and is also oscillatingly mounted to the base 3 as by brackets 6 to a pivot shaft 1 so as to be swingable toward or away from shaft 2, and carries a grinding or abrasive wheel 8 at its outer end in confronting rim relation with the cam 5 to be ground. A counterweight or spring constantly urges shaft l and its grinding wheel to swing toward shaft 2, while means is provided for controlling and limiting the approach of the grinding wheel 8 to cam 5 to grind it to the shape of template or master cam 4 through the action of a limiting roller or wheel 9 which bears upon the finished surface of the master cam 4.

Shaft I is really the extended shaft of the armature of an electric motor IE which revolves it and the grinding wheel 8 in direction of the arrow shown on the wheel, while the cam 5 to be ground is slowly revolved in the same direction by a motor ll through the intermediary of suitable worm gear reduction drive in housing 2.

While it was stated above that shaft l was oscillatingly mounted on pivot shaft 1, it is really the motor IU which is mounted on brackets 5 and these are rigidly secured to pivot shaft I, but of course the motor and its shaft 1 swing as a unit on the arc X (see Fig. 1) and they are resiliently urged to swing to the left (Fig. 4) so as to keep the grinding wheel in contact with the work cam 5, by means of a counterweight i 3 which is loosely housed Within an upward extension 3' of the base 3 and freely slidable up and down on a pair of spaced fixed guide rods 24. This weight engages a laterally extending lever or crank arm 15 which is rigidly secured at one end to the pivot shaft l and projects through an opening E6 in the side of the elevated part 3' of the base and into a hole ll in the weight where the end of it is impinged by a rounded end set screw |8 screwed through the upper portion of the weight IS. A weight is used as its pressure is uniform and not subject to the vibratory action of a spring.

The grinding wheel is of wider face than the rim cam to be ground and is trimmed to an absolutely true face parallel to shafts I and 2, and it should be about the same diameter as idler .wheel 9, for if it could be kept precisely the same diameter as wheel 9, and wheel 9 were also mounted on an extension of the motor shaft it would stop grinding when the new'cam 5 became the exact size and shape of master cam 4.

However, as the grinding wheel cannot be maintained at a definite constant diameter, a hand screw or feed adjustment is provided to vary the oscillatory relation of idler wheel 9 to the axis of the motor shaft l, and to carry this out idler wheel 9 is mounted on a separate short axle l9 projecting from the upper end 20 of a bracket 20 which is freely pivoted about pivot shaft '1 so that While it swings in the same are as does the motor 10 and grinding wheel 8 it is independent thereof, but idler wheel 9 is always kept pushed into rolling contact with the master cam 4 by means of a hand-screw 2| threaded through a lug 22 fixedly projecting from the end of the motor frame iii, and the inner end of which screw bears against the outer edge of the upper end 23 of bracket 20 so that by turning the screw 2! by means of its handle 23 the motor H1 and its grinding wheel may be forced to back off or away from the cam 5 being ground so as to be free of contact therewith, or by turning the screw in the opposite direction the Wheel may be permitted (under the action of the coun terweight H) to gradually approach the work and begin to grind it.

By this hand screw control the cam 5 may be brought down to the exact size and shape of the master cam, and by having the screw motion limited the grinding could proceed no further,

extended through the base to the motors.

but as stated, since the grinding wheel will gradually become smaller, the screw travel is made sufficient to permit grinding the work to some.- what smaller diameter than desired, and it is therefore carefully measured for correct final diameter and the grinding wheel backed off with the hand screw 2! when exactly right in size.

While the counterweight always urges the motor II] and its grinding wheel 8 toward the work, and through hand screw 2! also urges the idler wheel 9 against the master cam 4, still to prevent any possible back lash a compression spring 24 is positioned opposite the hand screw 2! reacting between bracket 29 and a lug 25 projecting from the motor frame [0.

The work shaft 2 is as stated, driven by a sep arate electric motor ll through worm gearing 01 other reduction gearing in gear box l2 so as to revolve slowly as the grinding wheel revolves at high speed against th work, however, since the idler wheel 9 is pressed against the master cam with some force it might urge shaft 2 to move ahead at such times as it was riding up to a high part of the master cam. This would be possible due to some backlash in the reduction gearing, and to prevent this a gentle tho constant brake pressure or frictional resistance is applied to the work shaft 2 by means of a brake strap 26 passing over a brake wheel or disk 2! secured to shaft 2 and provided with suitable adjustments to provide the required resistance.

Brake wheel 2! is provided with a finished hub 28 secured to shaft 2 and over which the master cam 4 fits and is held in place by a collar 29 and nut 30 on a reduced portion of shaft 2, while at the extreme end of the shaft is any desired type of detachable coupling 3| for connecting the shaft to the reduction gear output shaft connecting member 32.

Means is also provided to insure correct angular relation of the master cam and the cam being ground and prevent slippage from this position.

In the drawings this is carried out by a pair of driving pins 33 extending from the side of the brake wheel or disk 21 which enter a pair of corresponding holes drilled through the master cam. A similar construction is used at the opposite end of shaft 2 where the cam 5 being ground fits over a. hub 35 secured to the shaft and is angularly located as by one or more feather keys 36 over which it slides.

As the grinding wheel does not move axially with respect to the cam being ground as with many grinders, the wide face of the wheel must be kept true, and to do this quickly, just before sliding a new cam blank in place on hub 35 the special wheel dresser shown in Fig. 5 is placed on the hub 35 and moved back and forth longitudinally thereon while the grinding wheel is running to take off any slight irregularities. The amount of the cut may be accurately controlled by the hand screw 23. Of course the work shaft .2 will be stopped during this operation which requires but a few moments of time. The special dressing tool comprises a base portion 31 concavely curved to fit over hub 35 and provided with a keyway to slidably fit one of the feather keys 36. The cutting point 39 may be a diamond adjustably secured in a lug Mi provided on the base portion 31. A handle M facilitates manipulating the device.

Separate switches for the two motors are provided on the base 3 as shown at 52 and 43 in Fig. 1, and with the wiring (not shown) suitably Also the usual protective hood is provided over the grinding wheel as is well understood, but omitted from the drawings to more clearly show the relation of the parts.

From the above combined description and operation of the machine, its mode of operation and advantages will be easily understood by anyone skilled in the art, and while I show the grinding shaft as movable and the work shaft in fixed rotative position, this relation may be reversed while still maintaining advantages of the invention and my claims are intended to cover any such equivalents.

I claim:

1. In a rim-cam grinding machine, a rotatably mounted work shaft, means on said work shaft supporting a rim-cam blank to be ground to form, and means also supporting a master rim-cam on said work shaft in fixed angular relation to said cam blank, means for driving said work shaft, a grinding shaft provided with a grinding wheel in confronting rim relation to said cam blank, means mounting said grinding shaft for rotation and moving bodily toward and from said work shaft, an idler wheel arranged to roll against the rim of the master cam as the same is revolved with the work shaft, bearing means rotatably supporting said idler wheel and mounted for movement back and forth as the wheel is moved by the master cam, a driving motor on the grinding shaft, a hand screw arranged to react between the motor frame and said bearing means tending to force the idler wheel toward the master cam and thereby to control the separation of the grinding shaft from the work shaft, and means resiliently urging the two shafts toward one another.

2. In a rim-cam grinding machine, a hollow base plate, a work shaft and a grinding shaft rotatably mounted in parallel spaced relation above said base, the mounting of the grinding shaft including brackets secured to a pivot shaft in turn rotatably mounted upon said base whereby the grinding shaft may swing bodily toward and from said work shaft, means mounting a rimcam blank to be ground on one end of the work shaft, a grinding wheel mounted on the grinding shaft in confronting rim relation to the cam blank, an electric motor on said grinding shaft, a lever secured to and projecting laterally from said pivot shaft, a counterweight within said hollow base plate suspended from said lever urging said grinding shaft with its motor and grinding wheel to swing in direction of said work shaft,

a master rim-cam secured to said work shaft to which form the cam blank is to be ground, a bracket loosely pivoted to said pivot shaft, an idler wheel carried by the bracket arranged to roll against said master cam as it is revolved with the work shaft, and screw means extending between said grinding shaft and said bracket tending to force the idler toward said master rim-cam and back away said grinding shaft, for varying the effective distance between the grinding shaft and the work shaft,

3. In the construction as set out in claim 2 spring means reacting between said grinding shaft and said bracket urging it toward said screw means.

4. In the construction as set out in claim 2 a separate electric motor mounted on said base plate provided with speed reduction gearing detachably connected to drive said work shaft, and a brake active on said work shaft to hold same against turning in advance of its motor drive.

5. In the construction as set out in claim 2 a separate electric motor mounted on said base plate provided with speed reduction gearing detachably connected to drive said work shaft, and a brake active on said work shaft to hold same against turning in advance of its motor drive, and separate control switches for the two motors mounted on said base plate.

6. In the construction as set out in claim 2 said counterweight being slotted for reception of said lever, and movable up and down on guiding pins secured to the base plate.

7. In a structure as set out in claim 1 the means on the work shaft supporting a rim-cam blank to be ground to form, comprising a hub upon which the rim-cam blank is slidably secured and removable, and a grinding wheel dresser formed with a base adapted to slidably fit upon said hub When the cam blank is removed, said dresser adapted for manually moving back and forth along said hub when the Work shaft is still, and a grinding wheel dressing cutter mounted on said base in confronting relation to the rim of said grinding Wheel.

CHAS. W. LANG.

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