US2814915A - Grinding machine with oscillating rotary work holder - Google Patents

Description

Dec. 3, 1957 s. MESSERSCHMIDT GRINDING MACHINE WITH OSCILLATING ROTARY WORK HOLDER 4-Sheets -S'heet 1 Filed Jan. 14:, 1955 INVHW'OP 6BA$TIAN ME-SSBPSCHMZ'DT Dec. 3, 1957 I GRINDING MACHINE WITH OSCILLATING ROTARY WORK HOLDER s. MESSERSCHMIDT Filed Jan. 14, 1955 4 Sheets-Sheet 2 FIG 6 Hill-Ill" JTTORA/EX 1957 s. MESSERSCHMIDT 2,814,915

GRINDING MACHINE WITH OSCILLATING ROTARY WORK HOLDER Filed Jan. 14, 1955 4 Sheets-Sheet 3 INV ENT OR SEBASTIAN MESSERSCHMIDT ATTORNEY 2,814,915 GRINDING MACHINE. WITH OSCILLATING ROTARY WORK HOLDER Filed Jan. 14, 1955 Dec. 3, 1957 s. MESSERSCHMIDT 4 Sheets-Sheet 4 MEN OR qassssns'cnmofi' SEBASTIAN ATTORNEY United States Fatent GRINDING MACHINE WITH OSCILLATING ROTARY WORK HOLDER Sebastian Messerschmidt, Schweinfurt, Germany Application January 14, 1955, Serial No. 481,925

Claims priority, application Germany February 15, 1954 8 Claims. (Cl. 51-97) The invention relates to a swivelling mechanism for machine tools, particularly grinding machines.

Hitherto rings, especially those for ball bearings, were internally ground by the plunge-cut or oscillation method.

These methods are open to a number of objections and it is the object of the invention to overcome these in the manner hereinafter described with reference to the accompanying drawings, in which:

Fig. 1 is a diagram illustrating the known oscillation method;

Fig. 2 shows the grinding track produced by the method illustrated in Fig. 1;

Fig. 3 shows the grinding track which it is desired to produce;

Fig. 4 is a diagram of a swivelling mechanism according to the invention;

Fig. 5 is a vertical section through the head of the mechanism;

Fig. 6 is a detail view showing the cam disk arrangement on the king pin;

Figure 7 shows the gearing drive to king pin 8;

Figure 8 shows the linkage interconnecting the king pin 8 and the control shaft of the gearing of Figure 5;

Figure 9 shows the worm for driving the worm gear of the gearing shown in Figure 5;

Figures 10 and 11 show the linkage interconnecting the gearing of Figure 5 to the control shaft of the chuck of Figure 12, and

Figure 12 shows the drives for the grinding wheel and for the chuck.

According to Fig. 1 the ring 1 to be ground is held in a chuck 2. The grinding wheel 3 extends into the ring 1 and is driven by a motor through the intermediary of a shaft 4. The profile of the edge of the grinding wheel 3 corresponds to the radius R of the inner surface of the ring 1 to be ground.

When grinding the ring both the grinding wheel 3 and the ring 1 rotate. To maintain the radius of the grinding wheel on the profile thereof either the grinding wheel 3 or the chuck 3 is swivelled about the centre 0 while the grinding wheel 3 and the ring 1 rotate, the range of angular displacement of the centre line I-I of the grinding wheel being located between the dot-dash lines IIII and lIIIII. The advantage of the swivelling movement is that a certain radius R of the ring 1 has to be substantially retained. This is possible because the wear of the grinding wheel during the grinding operation is in accordance with the radius R. An objection to this method is that by swinging the workpiece or the grinding wheel the grinding track on the inner surface of the ring 1 is not rectilinear but in wave-like lines as shown in Fig. 2. A ring ground in this manner is unsuitable for a ball bearing for technical reasons in the operation and running of the balls. Consequently it is endeavoured to grind the ring so that the grinding track is rectilinear as illustrated in Fig. 3.

In the case of the plunge-cut method, the swivelling movement about the point 0 is eliminated (Fig. 1).

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Consequently a rectilinear grinding track similar to that shown in Fig. 3 is obtained. This method, however, is likewise not satisfactory because it is difiicult to obtain with the desired accuracy a certain radius R in the ring.

It has now been proposed to subject the inner surface of the ring first to an oscillating preliminary or rough grinding on one machine and then to a subsequent or final plunge-cut grinding on another machine. Although the advantages of both grinding methods are obtained by this subsequent grinding operation, the necessity of rechucking the workpiece represents an undesirably great loss of time. To reduce this, both oscillating and plunge-cut grinding operations were carried out on the same machine. During the dipping or plunge-cut grinding the oscillating movement must cease. Therefore an arrangement must be provided which allows the swivelling'movement to be controlled as required. Seeing that the known machine is serviced, that is the swivelling arrangement is switched on and oil, by the operator, 7

the position in which the swung part comes to a standstill relatively to the part which is not swung when the machine is stopped is dependent upon the skill of the operator. Consequently, although the necessity of rechucking the workpieces is done away with when rings are subjected to an oscillating preliminary rough grind ing and a plunge-cut final grinding on a single machine, the objection nevertheless arises that each time the swivelling device is switched off after the oscillating grinding operation, the swung part must be brought once more into its normal position. This, on the one hand, wastes time and, on the other hand, hinders production. Therefore it must be endeavoured to make the control of the grinding operation independent of the operator.

This is attained according to the invention in that the swivelling mechanism of a machine tool is equipped with an arrangement which automatically controls the starting and duration of the swinging movement.

The grinding machine disclosed includes a grinding wheel 65 and a chuck 2. The respective drives for the grinding wheel and the chuck are shown in Figure 12. The grinding wheel 65 and grinding spindle 64 are driven by motor 60 and belt and pulley gearing 61, 62, 63. The chuck is rotated by means of a motor 54 and belt and pulley gearing 56, 70, 57, 58, and shaft 59 upon which the chuck is mounted. The chuck is also given an oscillatory movement about a point 0 as indicated diagrammatically in Figure 4. This point 0, as it relates to Figure 12, lies on the axis of shaft 69 and the oscillation about this point takes place in a plane normal to the plane of the paper. The pulley 58 and the shaft 59 are included in this oscillatory movement which is permitted by a resiliently movable mounting of pulley 70. The oscillatory movement of these members is brought about by the oscillatory movement of shaft 69 on its axis caused by crank pin 7, connecting rod 5, eccentric pin 67 and eccentric 68 carried by the shaft as shown particularly in Figures 10, 11, and 12. The oscillatory movement of chuck 2, pulley 58 and shaft 59 is caused by the oscillation of a crank arm (not shown) on the end of shaft 69, the arm constituting a supporting base for the chuck, pulley and shaft. Such a supporting base is fully disclosed in applicants Serial No. 586,521 now pending before the Patent Ofilce. The radial distance of the crank pin 7 from the axis of rotation S can be changed while the crank 6, shown in Figure 4 and comprising parts 38, 43, shown in Figure 5, is turning. The crank gear is controlled by a kingpin 8. This pin carries two cam disks 9 and 10 with toe cams 11 and 12. These latter cooperate alternately with corresponding counter earns 13 and 14 on a control fork 15. The control fork 15 is connected to another fork 16 and pivotally mounted at 17. The fork 16 is provided with catch pins 18 and 19 which serve for shifting a shaft 20 by means of a sleeve 21. The shaft 20 carries at its other end a clutch member 22 which can mesh either with a bevel wheel 23 or with a bevel Wheel 24. A control member 26, which is pivoted at 27, engages the shaft 2h at 25. The control member 26 can be locked by means of a catch pin 28 cooperating with notches 29, 3t) and 31. The control member 26 has an extension 32 which cooperates with abutment 33. Another abutment 34 is adjustable by means of a screw bolt 35 and also serves for influencing the control member 26 as soon as it comes into contact with the counter abutment 34.

A worm wheel 37 is driven by a worm 36 which is in turn driven by a pulley 66 shown in Figure 9. This pulley is belt-connected to pulley 55 of motor 54. The worm wheel is connected with a hollow shaft 38 which constitutes a bearing for a spindle 39 which carries a bevel wheel 40. The spindle 39 can be screwed into and out of a slide 43 by means of a screw thread 41 engaging in a counter screw thread in the slide 43. The bevel wheel 40 meshes with the bevel wheel 23 and with the bevel wheel 24. The carriage or slide 43 carries the crank pin 7 to which the rod is connected (Fig. 4).

Referring to Figures 5, 6, 7 and 8, the king pin or king shaft 8 referred to above is driven in the following manner: Hollow shaft 38 carrying gear 45 drives the gear train comprising gears 46, 47, 48, shaft 49, change speed gearing 50, gears 51, and worm gearing 52, 53. Worm gear 53 is mounted upon the king pin or shaft 8 which as said above carries the cam discs 9 and for coaction with members 13 and 14.

The crank drive receives its rotary movement from the rotating worm 36 which drives the hollow shaft 38 through the intermediary of the worm wheel 37, thereby imparting a rotary movement to the slide 43 and consequently to the crank pin 7. The radial movement to lengthen or shorten the crank 6 is effected during the rotation of the pin 7 by adjusting the pin with the aid of the spindle 39. Its rotary movement is initiated by actuating the control clutch 22 which is effected from the king-pin 8. If, for example, the cam 11 of the cam disk 9 comes into contact with the counter cam 13 of the control fork during the rotation of the kingpin 8, the control fork 15 moves towards the left and lifts the shaft through the intermediary of the sleeve 21, so that the clutch member 22 connects the shaft 20 with the bevel wheel 23. As a consequence the spindle 39 rotates so that the slide 43 is shifted, for example, in the direction of the arrow D. At the same time the slide 43 and with it the crank pin 7 continue to rotate. During the displacement of the slide 43 the abutment 33 comes into contact with the extension 32 of the control member 26 causing the control member 26 to swing about the pivot pin 27 until it is arrested in its middle position by the engagement of the catch pin 28 in the notch 30. If the cam 12 on the cam disk 10 comes into contact with the counter cam 14 of the crank 15, this crank is shifted towards the right, the shaft 20 being moved downwards so that the clutch member 22 engages the bevel wheel 24. This again results in a displacement of the slide 43. In this case the displacement of the slide 43 is in the direction of the arrow E. Consequently the abutment 34 contacts the counter abutment 34' so that the control member 26 will be moved in clockwise direction, the catch pin 28 being shifted out of the notch 31 and into the notch 30. As a result the clutch member 22 again assumes its middle position.

The grinding operation proceeds as follows: The motors 54 and 60 are energized by any conventional means (not shown). The grinding spindle 64 and worm 36 are driven by their respective motors, and the king pin 8 is rotated by the above described gearing so that cam 11 engages with counter cam member 13 which, by means of the linkage 15-16, moves shaft 20 upward as shown in Figure 5. This movement is effective to engage clutch member 22 with the clutch member on gear 23 thus causing a movement of crank pin 7 outwardly in a radial direction as before referred to. The above described rotary movement of the slide 43 carrying the crank pin in conjunction with the outward movement of the crank pin causes, by means of the connecting rod 5, an oscillatory movement of member 68, shaft 69, and consequently of the chuck 2, the amplitude of the oscillations increasing as the crank pin 7 moves away from its center position. A point will finally be reached in the radial travel of the crank pin at which abutment 33 contacts abutment 32, which as stated above, will cause the disengagement of the clutch members on members 22 and 23. At this point, the chuck is at its maximum amplitude of oscillation and the grinding operation proceeds at this stage until the cam 12 is rotated to such an extent that it engages counter cam 14. Such engagement causes a closing of the clutch members on member 22 and gear 24 and this in turn, due to the reversal of rotation of screw shaft 39, as referred to hereinbeforc, will bring the crank pin 7 back to its central position. When this is reached, the abutment of member 34 with member 34' will cause a movement of member 22 from clutching position and into the neutral position shown in Figure 5. Under this condition the only movement imparted to the chuck is a rotative one, and consequently, the machine is now in readiness for the finishing grinding operation which now forthwith proceeds and which will form the grinding track of the character shown in Figure 3.

The crank pin 7 in moving from the middle point S, has moved outwards the length of the crank 6, then reversed and run back to S. As, during this time, the pin '7 rotates, an oscillating movement is maintained until the crank pin 7 is in the position S. In this position. although it rotates, it does not in any way influence the connecting rod 5 or chuck 2. Consequently the finish grinding of the ring I is carried out when the crank pin 7 is in this position. By this means it is possible with the aid of suitable cam disks on the kingpin 3 to carry out the grinding operation swinging the chuck relatively to the grinding wheel and a subsequent finish grinding operation without any swinging movement, the angle of swing being determined by the abutment 34 which can be adjusted by means of the screw bolt 35.

I claim:

1. In an internal surface grinding machine having a tool holder a grinding tool held thereby and a chuck oscillatable the one relatively to the other for grinding internal surfaces, such as the internal surfaces of the rings for ball bearings, a driving and control apparatus for controlling the commencement, the amplitude, and the duration of the oscillating movement of said chuck comprising a king pin, a rotary crank having an axis of rotation, a crank pin having a pin axis and carried by said crank to be automatically adjustable thereon from a predetermined radial position with respect to said axis of rotation to a radial position of coaxial alignment of said axis of rotation and of said pin axis where the radial position is zero and vice versa, control means for oper-- atively connecting said king pin with said rotary crank to automatically adjust the radial position of said crank pin between said predetermined radial position to said zero radial position thereof in dependence on the rotation of said kingpin, and a connecting rod connecting said crank pin with said chuck to effect said oscillating movement and control the amplitude thereof dependent on said radial position from a maximum thereof corresponding to said predetermined radial position to zero corresponding to said zero radial position to eifect finishing in said latter position.

2. In an internal surface grinding machine, the combination according to claim 1, wherein said crank pin carries a rotary slide, and wherein said control means includes means for shifting said slide in the radial direction of said crank.

3. In an internal surface grinding machine, the combination according to claim 1, wherein said crank pin carries a rotary slide, and wherein said control means includes means for shifting said rotary slide in the radial direction of said crank, said last-mentioned means including a spindle operatively connected with said slide and selectively operable means for stopping said spindle and selectively rotating the same in both directions.

4. In an internal surface grinding machine, the combination as set forth in claim 1, further comprising a rotary slide mounted on said crank pin, a spindle operatively connected with said crank pin to shift said slide in the radial direction of said crank, and driving means cooperating with said slide including transmission elements and a coupling member selectively engageable with either of said transmission elements to impart rotary movement to said slide in opposite directions.

5. In an internal surface grinding machine, the combination according to claim 1, further comprising a rotary slide carried by said crank pin, a spindle operatively connected with said rotary slide, drive means including a clutch and transmission elements for drivingly connecting said spindle with said slide to impart to the latter a rotary movement in one or the other direction of rotation, a locking element for locking said clutch in the disengaged position thereof and in each engaged position, a shiftable shaft operatively connected with said locking element, and cam disk means operatively connected with said shiftable shaft to control the position of said clutch.

6. In an internal surface grinding machine, the combination according to claim 1, further comprising a rotary slide carried by said crank pin, a spindle operatively connected with said rotary slide, drive means including a clutch and transmission elements for selectively rotating said spindle in opposite directions, a locking mechanism for looking said clutch in the disengaged position and in each position of engagement with one of said transmission elements, a shiftable shaft operatively connected with said locking mechanism, and cam disk means operatively connected with said vshiftable shaft to control the position of said clutch.

7. In an internal surface grinding machine, the combination as set forth in claim 1, further comprising a rotary slide carried by said crank pin, a spindle cooperating with said rotary slide to shift said slide in the radial direction of said crank, driving means including a clutch and transmission elements operatively connected with said slide to impart rotary movement thereto in opposite directions, and locking means for locking said clutch in the disengaged position and in each position of engagement including a control member opposite said slide having an extension limiting the swinging movement of said control member, an abutment, and counterabutments cooperating with said abutment to disengage said clutch at the two extreme positions of the length of said crank.

8. In an internal surface grinding machine, the combi nation according to claim 7, wherein said abutment is adjustable to determine the maximum length of said crank.

References Cited in the file of this patent UNITED STATES PATENTS 857,791 Clark June 25, 1907 1,923,762 Stevens Aug. 22, 1933 1,927,552 Long Sept. 19, 1933 2,168,843 Lockhart Aug. 8, 1939 2,176,154 Shannon Oct. 17, 1939

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