US3468069A

US3468069A - Multiple master cams for cam grinding machines

Info

Publication number: US3468069A
Application number: US613794A
Authority: US
Inventors: John R Fries; Ralph E Price; John A Boller
Original assignee: Landis Tool Co
Current assignee: Landis Tool Co
Priority date: 1967-02-03
Filing date: 1967-02-03
Publication date: 1969-09-23
Anticipated expiration: 1986-09-23

Description

Sept. 23, 1969 J. R. FRIES ETAL MULTIPLE MASTER CAMS FOR CAM GRINDING MACHINES Filed Feb. 5, 1967 4 Sheets-Sheet 1 INVENTORS JOHN R. FRIES RALPH 5. PRICE JOHN A. BOLLER Sept. 23, 1969 J. R. FRIES ETAL MULTIPLE MASTER CAMS FOR CAM GRINDING MACHINES Filed Feb. 5, 1967 4 Sheets-Sheet 2 JOHN :2. runs RALPH 2. PRICE JOHN A. son.

BY M PM. Ma 4Z1 ar'roausvs Sept. 23, 1969 J. R. FRIES ET AL 3,468,069

MULTIPLE MASTER CAMS FOR CAM GRINDING MACHINES Filed Feb. 3. 1967 4 Sheets-Sheet 3 JOHN R. FRIES RALPH E. PRICE JOHN A. BOLLSR (P ZZ I 3 g am/U ATTORNEYS P 1969 J. R. FRIES ETAL. 3,453,069

I MULTIPLE MASTER CAMS FOR CAM GRINDING MACHINES Filed Feb. 3, 1967 4 Sheets-Sheet 4 INVENTORS JOHN R. FRIES RALPH E- PRICE JOHN A. ROLLER RNEYS United States Patent 3,468,069 MULTIPLE MASTER CAMS FOR CAM GRINDING MACHINES John R. Fries and Ralph E. Price, Wayneshoro, Pa., and John A. Boller, Thurmont, Md., assignors, by mesne assignments, to Landis Tool Company, Waynesboro, Pa., a corporation of Delaware Continuation-impart of application Ser. No. 390,916, Aug. 20, 1964. This application Feb. 3, 1967, Ser. No. 613,794

Int. Cl. B24b 7/00 US. Cl. 51-101 9 Claims ABSTRACT OF THE DISCLOSURE This subject has to do with a cam grinding machine and particularly relates to the construction of the master cam and the shifting of a cam follower relative thereto. For each cam component to be ground, the master cam has a plurality of master components so that the cam grinding machine is adapted to effect the grinding of a plurality of different cam components. The machine is not only provided with the conventional means for shifting the cam follower between master cam components in one set of master cams, but also with power means to shift the cam follower from a master cam component in one set of master cams to a master cam component in another set of master cams without in any way disassembling the drive mechanism.

This application is a continuation-in-part of our copending application Ser. No. 390,916, filed Aug. 20, 1964, and entitled Multiple Master Cams for Cam Grinding Machines; now US. Patent No. 3,303,614, issued Feb. 14, 1967.

The invention relates to machines for grinding cams, particularly the cams of automotive camshafts.

The process of manufacturing automotive camshafts involves first, models of intake and exhaust cam contours. Using these models as masters, a master camshaft is ground having a separate master cam for each cam on the product shaft.

In the grinding of the master camshaft, the model is rotated in engagement with a follower either in the form of a shoe or roller having an arcuate surface of a radius corresponding to the radius of the grinding wheel to be used to grind the product cam. In order to grind the product cam with maximum accuracy, the grinding wheel should be of constant diameter. Since this is impossible, the grinding wheel must be replaced after a certain amount of wear. For example, a full size wheel may be worn to a certain diameter. If the wheel is worn to a smaller diameter, the contour of the product cam would not be ground within specified limits.

According to the prior practice, the follower used with the model cam has an arcuate surface of a radius of a half-worn wheel. When a wheel is worn to a minimum diameter, it is replaced by a larger wheel.

In order to continue utilizing the Worn grinding wheel, we found that by providing the master cam with one or more additional sets of cam components in accordance with the smaller grinding wheel diameters, we could continue to use the same grinding wheel on the cam grinding machine and still accurately grind the desired cam shaft.

Patented Sept. 23, 1969 The additional sets of master cam components were ground for particular diameters of half worn grinding wheels. We also provided the cam grinding machine with power means for shifting the cam follower from one set of master cams to another set of master cams in accordance with the change in diameter of the grinding wheel.

We have found that our invention is not restricted to the grinding of a single cam shaft configuration utilizing different diameters of grinding wheels. By utilizing a single grinding wheel of a predetermined diameter range and providing the master cam with different sets of cam components for grinding different cam shafts, the cam grinding machine may be quickly converted from the grinding of one camshaft to a similar camshaft having different cam component designs.

We have also found that by providing power means for shifting the cam follower from one set of master cams to another of the set of master cams, with the power shifting means supplementing the means for shifting the I cam follower from one cam component to another cam component in the same set of master cams, the conversion of the cam grinding machine for grinding different cam shafts may be accomplished without disconnecting any portion of the drive train.

In view of the foregoing, it is the object of this invention to provide a cam grinding machine with multiple sets of master cams, there being one set for each different camshaft to be ground, and with power means for shifting the cam follower from one set of master cams to another set of master cams whereby the operator of the cam grinding machine may adjust the cam grinding machine to grind different cam configurations and/ or timings.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings:

In the drawings:

FIG. 1 is a plan view of a camshaft grinding machine.

FIG. 2 is a partial plan view showing the master cam roller in engagement with one of two adjacent master cams of different sets, either of which may be used to grind a given product cam depending on the diameter of the grinding wheel.

FIG. 3 is a partial end elevation showing the device for shifting the master cam follower from one set of master cams to another set.

FIG. 4 is a hydraulic and electric circuit.

FIGS. 4A and 4B are fragmentary modified portions of the hydraulic circuit.

FIG. 5 is a diagram of apparatus for grinding a master cam for a full size grinding wheel.

FIG. 6 is a diagram of apparatus for grinding a master cam for a half-worn grinding wheel.

The invention includes a master camshift having multiple sets of master cams, each set being different from the other as to configuration and/or timing. For the purpose of illustration, two sets of master cams are described.

The individual cams of the two sets of master cams are arranged alternatively on a common shaft. When the sets of master cams are to be used in conjunction with grinding wheels of different diameters, but to grind the same camshift, one set is ground with a follower corresponding to a full size grinding wheel, and the other set is ground with a follower corresponding to a smaller diameter grinding wheel. The diameter of the follower corresponding to the large wheel will be half-way between the maximum and minimum diameter of such a wheel. The diameter of the follower corresponding to the worn wheel will be half-way between the maximum and minimum diameters of such a wheel.

A hydraulic or pneumatic piston connected to a follower through a shifter member serves to shift the roller between adjacent master cams. In one position, it will automatically and successively engage all the master cams of one set. In other positions, it will automatically and successively engage all the cams of the other sets. The signal for shifting the follower roller from one position to another may be provided by limit switches operable from the dressing tool or the wheelbase when either of these is in the position corresponding to a mean diameter grinding wheel. Such limit switches function through solenoid operated reversing valves. The change in position of the wheelbase or dressing tool to accommodate a new and larger grinding wheel is effective through said limit switches to reset the follower roller to the set of master cams corresponding to the larger grinding wheel.

The circuit for operating the roller shifting mechanism includes a contact whereby the roller may be shifted only when the carriage is in one end position or any other time when the shifting does not interfere with the grinding operation. For example, the roller should not be shifted at any time during the grinding of a camshaft. On the other hand, if it is considered necessary to shift the roller before all the cams on the shaft have been ground, control means may be provided for retracting the master cam before the roller can be shifted.

Numeral includes the bed of a grinding machine. Work carriage 11 has a headstock 12 at one end and a footstock 13 at the other end. Headstock 12 and footstock 13 have

centers

14 and 15 respectively for rotatably supporting camshaft W.

Master camshaft is rotatably mounted in bearings 22 and 23 in headstock 12 in axial alignment with center 14.

The means for rotating master camshaft 20 and camshaft W consists of a motor 21 operable through a suitable 'belt drive.

Master camshaft 20 has two sets of contours A and B, arranged alternately on said master camshaft. Contours A are for use with a full size grinding wheel. Contours B are used when grinding wheel 30 has worn to a predetermined smaller diameter.

In FIG. 5, master camshaft 20 is mounted for rotation in axial alignment with model cam 61 which is the same size as the produce cam on camshaft W. Master cam contours A and B are ground by means of grinding wheel 60 of substantially the same diameter as follower 25 which is to engage cam contours A and B. For grinding contours A and B, follower roller 62 engaging model cam 61 may have a radius half-way between that of the full size grinding wheel and the minimum diameter wheel which can be used with contours A and B.

In FIG. 6, grinding wheel 60 is shown in engagement with one of the master cam contours B. Follower roller 63 engaging model cam 61, in this case, has a radius equal to the mean radius of a half-worn grinding wheel.

Master cam follower 25 is rotatably and slidably mounted on shaft 26 in a manner disclosed in US. Patent 1,993,854, granted Mar. 12, 1935 and U.Sl. Patent 2,323,- 189, granted Ian. 29, 1943.

The means for shifting master camshaft 20 toward and from operative engagement with follower 25 consists of a piston and cylinder (not shown) in housing 27, but well known in this type of machine.

Grinding wheel 30 is rotatably mounted on a wheel support (not shown) for movement toward and from camshaft W.

The means for shifting follower 25 from one set of master cam contours to another is a piston slidably mounted in cylinder 41 and having a slot 42 for receiving follower 25. Cylinder 41 is mounted on and forms a part of bracket 45 which connects follower 25 with the roller indexing device shown in said mentioned US. patents.

The means for shifting the follower 25 from one master cam to another in a set of master cams is also disclosed in the above mentioned Patents 1,993,854 and 2,323,189 and includes a chain 46 which is fixedly secured to the bracket 45 for automatically shifting the bracket 45 and the cam follower 25 carried thereby as there is a relative shifting of the cam shaft being ground with respect to the grinding wheel.

Operation Follower 25 is normally in engagement with the set of cam contours A.

When grinding wheel 30 has been reduced by wear and dressing to a smaller diameter, cam 55 on dressing device 56 closes limit switch contact 12LS1 in a circuit to the follower shift right relay 16CR.

This circuit also includes normally opened contacts 15CR1 and 16CR1 in parallel and normally closed contact 17CR1.

Follower 25 cannot be shifted while in engagement with master camshaft 20.

Limit switch 6LS is closed when master cam contours A and follower 25 are separated, to complete a circuit to energize relay 15CR. Thus, the relays for shifting follower 25 cannot function unless said follower 25 and master cam are separated.

Contact 15CR1 completes a circuit through limit switch contact 121.81 and normally closed contact 17CR1 to energize relay R.

Contact 16CR1 in parallel with contact 15CR1 is a holding contact.

Contacts 16CR3 and 16CR4 complete a circuit to energize valve solenoid 7, shifting valve 50 to the right. In this position, valve 50 cuts off the supply of fluid under pressure to the left end of valve 70 and connects it with exhaust.

Fluid under pressure is then directed through valve 51 to the right hand end of valve 70, shifting said valve to the left and directing fluid under pressure to the left hand end of piston 40 to shift follower 25 to the right to operative relation with the master cam contours B.

When grinding wheel 30 is worn to its minimum limit it is replaced by a new full size wheel.

Dressing device 56 and cam 55 are reset in accordance with the diameter of the full size wheel. Resetting cam 55 closes contact 12LS2 and opens contact 12LS1.

Closing contact 12LS2 completes a circuit from contact 15CR2 through normally closed contact 16CR2 to energize relay 17CR.

Normally closed contact 17CR1 opens to deenergize relay 16CR.

Contact 17CR2 is a holding contact.

Contacts 17CR3 and 17CR4 close to complete a circuit to energize solenoid 8.

Solenoid 8 shifts valve 51 to the right, cutting 01? the supply of fluid under pressure to the right hand end of valve 70, permitting said valve to be shifted to the right. In this position, valve 70 directs fluid under pressure to the right hand end of cylinder 41, shifting piston 40 and follower 25 to the left.

It will be readily apparent from the foregoing that a master camshaft having multiple sets of master cams to be utilized in accordance with the diameter of a grinding wheel to grind a single camshaft will be particularly adapted to long run operations. On the other hand, it will be readily apparent that the same principle can be utilized in relatively short run operations to grind camshafts having diflerent cam shapes without replacing the master cam. The same power means may be utilized to shift from one set of master cams to another so as to readily adapt the cam grinding machine to grind different cam shapes.

When the master camshaft has only two sets of master cams thereon, the same hydraulic system may be utilized for positioning the follower 25. However, a manual switching mechanism should be provided for selectively engaging the follower 25 with the desired set of master cams. As is best illustrated in FIGURE 4, this switching mechanism may assume the simple form of a selector switch SS. The selector switch SS will be of a conventional type having a neutral open position which is the Auto position of the electrical system and two operative positions \A and B.

The central movable contact of the selector switch SS is connected to the lead L1 through contact CR3 and when the selector switch SS is in the A position, a circuit is completed through the normally closed contact 17CR1 to energize the circuit relay 16CR irrespective of the closing of the switch contact 12LS1. The energization of the relay 16CR will result in the opening of the normally closed contact 16CR2 so as to open the circuit to the circuit relay 17CR irrespective of the condition of the switch contact 12LS2. As desribed above, the energization of the circuit relay 16CR will result in the energization of the solenoid 7 and the operation of the hydraulic system to move the piston 40 and the cam follower 25 to the right-hand position of FIGURE 4.

When the selector switch SS is moved to the B position, the circuit relay 17CR will be energized with the resultant energization of the solenoid 8 and the operation of the hydraulic system to shift the piston 40 and the follower 25 to the left-hand position thereof.

After the shifting of the piston 40 and the follower 25 has been completed, valve 70 will be centered, blocking both ends of the cylinder 41 so that the piston 40 will be locked in place. If desired, a suitable timing relay could be incorporated in the selector switch SS to automatically accomplish this.

When the master camshaft is provided with more than two sets of master cams, means must be provided for placing the piston 40 and the follower 25 in intermediate positions. In FIGURE 4A there is illustrated a modified portion of the hydraulic system which will permit this. It is to be noted that the cylinder 41 is of an extended length whereby in the illustrated form four piston positions may be obtained. The piston 40 is provided with a piston rod 43 which has formed therein a plurality of notches 47 in which a spring loaded ball detent 48 is seatable to accurately position the piston 40. It is to be understood that when the selector switch SS is properly positioned, fluid will be admitted to the cylinder 41 in the proper direction to effect the shifting of the piston 40. By watching the movement of the piston rod 43 and moving the selector switch SS to its auto or olf position when the ball detent 48 is positioned in the correct notch, the follower 25 may be readily aligned with the selected set of master cams. It is to be understood that the piston 40 will be locked in a selected position as described above.

In FIGURE 4B there is illustrated a portion of a hydraulic system which may be manually actuated to effect the positioning of the piston 40 and the follower 25. A normally closed valve 80 is coupled between the two lines leading to the cylinder 41 for the purpose of bypassing valve 70 to permit manual shifting of the piston 40. When the valve 80 is opened, the piston 40, roller 25 and piston rod 43 may be manually shifted. In order to facilitate the shifting of the piston rod 43 and the accurate positioning thereof, the piston rod 43 may be provided with a rack portion 71 which is meshed with a pinion 72. The pinion 72 may have a suitable lever 73 attached thereto for effecting the rotation thereof and the accurate positioning of the piston rod 43. It is to be understood that other types of actuators may be utilized in place of the rack and pinion drive.

It is to be understood that after the piston 40 has been manually positioned to accurately position the follower 25 relative to the master camshaft, the valve is again closed and the piston 40 and follower 25 are hydraulically locked in the selected position.

It will be apparent from the foregoing that the follower 25 may be selectively aligned with different master cam sets, each of which corresponds to a different product camshaft. It will also be apparent that the cam follower 25 may be shifted to the desired positions in alignment with predetermined sets of master cams without in any way disconnecting the drive mechanism for the follower 25 which is utilized to automatically shift the cam follower 25 as a grinding operation on a multiple lobe carnshaft proceeds.

Although only a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the disclosed camshaft grinding machine without departing from the spirit and scope of the invention, as defined in the appended claims.

We claim:

1. In a camshaft grinding machine,

(a) a base,

(b) a grinding wheel support on said base,

(c) a grinding wheel rotatablymounted on said wheel support,

(d) a work support comprising,

(e) a carriage slidably mounted on said base,

-.(f) a headstockand a footstock on said carriage for rotatably supporting a camshaft,

(g) a master camshaft in said headstock having multiple sets of master cams with corresponding individual master cams of the different sets being adjacent to one another,

(h) a master cam follower,

(i) first means for shifting said follower along said master camshaft from one master cam to the next in the same set of master cams,

(j) and second means for shifting said follower from one set of master cams to another.

2. In a camshaft grinding machine according to claim 1 wherein (a) said second means for shifting said follower are power means.

3. In a camshaft grinding machine according to claim 1 wherein (a) said second means for shifting said follower includes a piston and cylinder.

4. In a camshaft grinding machine according to claim 1 wherein (a) said first means for shifting said follower includes a bracket,

(b) and said second means for shifting said follower are carried by said bracket.

5. In .a camshaft grinding machine according to claim 4 wherein (a) said second means for shifting said follower includes a piston and cylinder.

6. In a camshaft grinding machine according to claim 1 wherein (a) said first means for shifting said follower includes a bracket,

(b) and said second means for shifting said follower includes a cylinder carried by said bracket and a piston movable in said cylinder under power,

(0) and said follower being connected to said piston.

7. In a camshaft grinding machine according to claim 1 wherein (a) said second means for shifting said follower is operable independent of said first means for shifting said follower.

8. In a camshaft grinding machine according to claim 1 wherein (a) said second means for shifting said follower is operable to shift said follower relative to said first means.

7 8 9. In a cam grinding machine, References Cited (a) multiple sets of master cams with the individual UNITED STATES PATENTS master cams of each set arranged alternately, (b) a master cam follower for said sets of master cams, 1,993,854 3/1935 Ott 51101 (c) and power means to change the position of said 5 2523389 6/1943 Balslger master cam follower from the master cams of one $303,614 2/1967 Fngs set to the adjacent master calms of another set, thus I positioning said follower for all other master cams LESTER SWINGLE Primary Exammer in said other set.