US3650076A

US3650076A - Grinding machine

Info

Publication number: US3650076A
Application number: US28716A
Authority: US
Inventors: Herbert R Uhtenwoldt; William H Grotewold; Bruno E Straub
Original assignee: Heald Machine Co
Current assignee: Heald Machine Co
Priority date: 1970-04-15
Filing date: 1970-04-15
Publication date: 1972-03-21
Anticipated expiration: 1989-03-21

Abstract

This invention relates to a grinding machine and, more particularly, to apparatus for bringing about various cross-feed motions in a machine for finishing workpieces by the abrasive process.

Description

United States Patent Uhtenwoldt et a1. Mar. 21, 1972 54 GRINDING MACHINE [56] References Cited [72] inventors: Herbert R. Uhtenwoldt, Worcester; Wil- UNITED STATES PATENTS Iiam H. Grotewold, Holden Bruno E.

1 2,486,244 10/1949 Balslger et a1 ..51/l65.92 X wmeste" Mass 2,985,988 5/1961 Johnson et a]. ..51/50 R [73] Assignee: The Heald Machine Company, Worcester, 1 3,403,480 10/1968 Robillard .51/ 165.87 Mass. 3,503,158 3/1970 Robillard et a1. ..5 l/165.8

3,561,168 21971 d l 22 Filed: Apr. 15, 1970 Rbmar 5 I 165 75 [21] APPLNQ; 23 Primary Examiner-Lester M.Swing1e Att0rney-N0rman S. Blodgett [52] U.S.Cl ..5l/165.89,5l/l65.8,5l/l65.9 57 ABSTRACT [51] Int. Cl ..B24b 49/00 [58] Field of Search ..51/165.89, 165.77, [65.8, 165.81, Thls mvemlon relates to a s s machine and, more p ticularly, to apparatus for bringing about various cross-feed motions in a machine for finishing workpieces by the abrasive process.

10 Claims, 2 Drawing Figures COMPENSATION COARSE 43 i ii POSITIONING 1 1|: FINE 44 POSITIONING PATENTEDHARZI I972 SHEET 1 [IF 2 INVENTORS HERBERT R. UHTENWOLDT WILLIAM H. GROTEWOLD BRUNO ESTRAUB BY ATTORNEY PAIENIEUHARZI I972 SHEET 2 [IF 2 BASE COMPENSATION FINE POSITIONING COARSE POSITIONING GRINDING MACHINE BACKGROUND OF THE INVENTION In the art of grinding and, particularly, internal grinding, it is necessary to move the abrasive wheel relative to the workpiece through a cycle of rather complex longitudinal and transverse motions. While the longitudinal or traverse motions are relatively crude'and need not be performed with any degree of accuracy, the transverse or feed motions must be done very accurately because they determine not only the size of the finish surface but its shape and finish. Any number of methods have been used for producing these transverse motions in the past. Generally speakingflhey have all been quite complicated and expensive. Furthermore, they have been difficult to adjust and to maintain. These and other difliculties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a grinding machine having a relatively simple and inexpensive cross-feed means.

Another object of this invention is the provision of a crossfeed apparatus for a grinding machine which is rugged in construction and which is capable of a long life of useful service with a minimum of maintenance.

A further object of the present invention is the provision of a feed means which is particularly adapted to operation by means of electrical pulses, thus permitting digital control.

A still further object of the invention is the provision of a grinding machine with a cross-feed means, such that the feed slide can be moved to dress position'at any time in the cycle without disturbing the setting of the feed mechanism.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts setforth in the specification and covered by the claims appended hereto.

SUMMARY OF THE INVENTION A rod extension is mounted in the table in alignment with the rod and a slidable connection exists between the feed rod and the rod extension to permit relative axial sliding movement between them, but to cause them to rotate together. A means is mounted in the table to cause the sliding motion relative to the feed rod for grinding feed and for dress retraction movements and means is also mounted in the table and surrounding the extension to cause rotation of the extension and the rod for p roducing compensation and adjusting movements of the table.

More specifically, a rotatable cam is mounted in the table for bringing about the said sliding motion-to cause relative motion between the wheelhead table and the workhead transversely of the base to bring about a grinding operationfand the cam is rotated by a stepping motor which receives feed pulses from a control apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS The character of the invention, however, may be best understood by reference toone of its structural forms, as illustrated by the accompanying drawings, in which:

FIG. 1 is a perspective view of a grinding machine embodying the principles of the present invention, and

FIG. 2 is a horizontal sectional view of the machine taken on the line IIII of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, wherein are best shown' the general features of the invention, the grinding machine, indicated generally by the reference numeral 10, is shown as being of the type known as a universal" grinding machine in that it is not only capable of automatic production work, but also is capable of being used as a toolroom machine for machining small lots of workpieces; the machine is of the type shown and described in the patent of Johnson et al., U.S. Pat. No. 2,985,988. It is provided with a base 11 on which is mounted a workhead 12 having a dressing apparatus 30 and having a rotatable chuck 13 for carrying a workpiece 14. In the preferred embodiment, the invention is shown as being set up as an internal grinding machine to finish a bore in the work piece 14. On the base is also mounted a wheelhead table 15 for carrying an abrasive wheel 20. Mounted at the front of the table is a feed box 16. Mounted on the base at the rear thereof is a control apparatus 17 connected by suitable electrical cables 23 to the feed box 16. The control apparatus is similar to that shown in the patent of Robillard U.S. Pat. No. 3,403,480 and consists of digital equipment including logic circuits and counters to provide a feed stepping motor with electrical pulses. Also mounted on the front of the control apparatus is a digi-switch readout-and-setting apparatus 18 similar to that shown in the patent application of Robillard Ser. No. 720,912, filed Apr. 12, 1968, now U.S. Pat. No. 3,561,168, dated Feb. 9, I971.

Referring now to FIG. 2, which shows the details of the cross-feed apparatus, it can be seen that the base 11 is connected to the wheelhead table 15 by a feed rod 19. For the purposes of the description which follows, the feed box 16 will be considered as part of the table, since it is fastened to its forwardly directed surface and moves with it. As is evident in the drawing, the rod 19 is mounted in the table 15 in such a way that the table can slide relative to the base 11 and relative to the rod 19 itself. The rotatable cam 21 is mounted in the table 15 for bringing about the said sliding motion. This is done to cause relative motion between the wheelhead table 15 and the workhead 12 transversely of the base to bring about a grinding operation.

The cam 21 is rotated by a stepping motor 22 which is connected by the flexible cable 23 to the control apparatus 17.

The cam engages and moves a cam follower 25 which is mounted on one end of a lever 24, the other end of which is pivotally fastened to the table 15. An intermediate portion is pivotally fastened to the feed rod 19 by means of a pivot pin 26 to produce the sliding motion. The feed rod 19 is fastened to the base 11 by a threaded connection consisting of a I threaded portion 27 of the rod threadedly engaging a nut-like element 28 fastened to'the base. A reduced cylindrical portion 29 of the rod is slidably engaged in a bore 31 formed in the element 28 and pressure fluid access is provided through a passage 32 in the base. Rotation of the feed rod 19 produces relative axial movement between the rod and the base and this serves to move the table 15 also.

A rod extension 33 is rotatably mounted in the table in alignment with the rod 19 and is connected with it by means of pegs 34. These pegs provide a slidable connection between the feed rod and the rod extension to permit relative axial sliding movement between them but to cause them to rotate together. Surrounding the extension is a one-way clutch 35 (details of 'which are not shown) which has an arm 36 extending radially selected side of thepiston 38. Pressure fluid is introduced to the front side of the piston to produce a dress retraction movement on occasion of the table 15 relative to the base 11. The

' back end of the piston is then thrown to the rear of the bore 39 It is possible to provide coarse positioning by the rotation of a plate 43 mounted at the front of the feed box 16 and having a handle 44, the rotation of the plate serving to rotate the extension 33. Similarly, for fine positioning, it is only necessary to rotate a dial knob 45 which also operates on the extension 33 and serves to rotate the feed rod 19. The fine positioning knob 45 operates through a differential gear apparatus 46 (the details of which are not shown) to rotate the extension 33 at a much slower rate than a similar rotation of the plate 43.

OPERATION The operation of the apparatus will now be readily understood in view of the above description. The workpiece 14 is set up in the chuck 13 and the workhead l2 drives the chuck and rotates the workpiece in the usual way. The abrasive wheel 20 is advanced longitudinally of the base 11 and transversely relative to the workpiece 14 by the usual control apparatus under the regulation of the control apparatus 17. All the movements are displayed in the digi-switch apparatus 18, so that the operator always knows where the abrasive wheel is located simply by looking at the readout. In order to feed the abrasive wheel toward the surface to be finished in the workpiece, the cam 21 is rotated by the stepping motor 22. This stepping motor receives pulses from the control apparatus 17 and the pulses are counted and displayed on the apparatus 18. Rotation of the cam pivots the lever 24 about its pivoted end and operates through the pivot pin 26 to move the table rearwardly relative to the rod 19. Pressure fluid exists in the passage 41 so that the piston 38 is positioned toward the front of the bore 39 so that the pin 26 urges the lever 24 and the cam follower 25 against the cam 21. The grinding portion of the cycle is terminated in the usual way by the engagement of the wheelhead table 15 with a switch or by a suitable indication from an in-process gage, or simply by the counting of the number of pulses reaching the stepping motor and displayed in the digi-switch apparatus 18. However, this portion of the cycle is terminated, the stepping motor 22 receives negative pulses and operates in the reverse direction to rotate the cam in the direction from which it came; the lever 24 and the table 15 follow it in the forward direction. The wheel is retracted from the workpiece either for dress by the dressing apparatus 30 or for termination of the cycle by introducing oil into the passage 42 which causes the table to move forwardly until the piston 38 engages the rearward end of the bore 39. It is interesting to note that dress can take place at any time and as many times as desired during the cycle and the cam rotation is stopped until the dressing operation is completed. Thus, the wheelhead table is returned to the same cross-feed position on the cam as before the dressing cycle started. Compensation is introduced through the motor 37, but, of course, the diamond removes material from the wheel. This means that, even though the table is advanced rearwardly relative to the base 11, the wheel surface remains the same when the cam follower 25 again engages the cam 21.

In order to cause the dressing apparatus of the machine to remove a satisfactory amount of the wheel surface to renew it, it is necessary to provide a compensation movement, and this is accomplished by rotating the rod 19 so that it advances closer to the base 11. Fluid pressure is introduced into the motor 37 to reciprocate it and the angular to-and-fro motion of the arm 36 causes uni-directional rotation through the oneway clutch 35 of the extension 33. The extension, of course, is keyed to the rod 1.9 by the pins 34 and, therefore, this causes rotation of the rod. Before every dressing cycle, the operation of the compensating motor 37 will move the table and the wheel further to the rear to allow the dressing diamond to remove a substantial portion of the abrasive wheel; the effective surface of the wheel for grinding, of course, remains in the same plane in the well-known manner, this plane being dictated by the position of the dressing diamond on the dressing apparatus 30. Initial adjustment or adjustments during successive grinding cycles can be produced by use of the handle 44 rotating the plate 43 which operates directly on the extension 33, and rotates the rod 19 and produces rearward movement of the table 15 in a direct proportion. When it is desired to make fine adjustments, however, the rotation of the knob 45 operates through the differential gear apparatus 46 and produces considerably less than a full revolution of the rod 19 for a full revolution of the knob 45. This permits fine adjustit is obvious that minor changes may be made in the fonn and construction of the invention without departing from the material spirit thereof. it is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

1. A grinding machine, comprising a. a base having a workhead mounted at one end,

b. a wheelhead table mounted at the other end,

c. a feed rod extending between the table and the base and being mounted in the table for longitudinal sliding motion relative thereto, and

d. a rotatable cam mounted in the table for bringing about the said sliding motion to cause relative motion between the wheelhead table and the workhead transversely of the base to bring about a grinding operation.

2. A grinding machine as recited in claim 1, wherein the cam is rotated by a stepping motor which receives feed pulses from a control apparatus.

3. A grinding machine as recited in claim 1, wherein the cam engages and moves one end of a lever, the other end of which is pivotally fastened to the table, and wherein an intermediate portion of the lever is pivotally fastened to the feed rod to produce the sliding motion.

4. A grinding machine as recited in claim 1, wherein the feed rod is fastened to the base by a threaded connection, so that rotation of the feed rod produces relative axial movement between the rod and base.

5. A grinding machine as recited in claim 4, wherein a oneway clutch surrounds the feed rod, an arm extends radially from the exterior of the clutch, and a reciprocable fluid motor engages the outer end of the arm to produce incremental rotation of the rod to produce compensating sliding movement of the table relative to the base.

6. A grinding machine as recited in claim 1, wherein the feed rod is provided with a concentric piston which is slidable in a cylinder bore formed in the table, and wherein means is provided to introduce pressure fluid into the bore selectively on one side of the piston to produce dress retraction movement of the table relative to the base or to the other for grind- 7. A grinding machine, comprising a. a base,

b. a table mounted on the base for sliding motion thereover,

c. a feed rod extending between the table and the base and being mounted in the table for rotation and axial sliding motion relative thereto,

d. a rod extension mounted in the table in alignment with the rod,

e. a slidable connection between the feed rod and the rod extension to permit relative axial sliding movement between them but to cause them to rotate together,

f. a first means mounted in the table to cause the sliding motion relative to the feed rod for grinding feed and for dress retraction movements, and

g. a second means mounted in the table and surrounding the extension to cause rotation of the extension and the rod for producing compensation and adjusting movements of the table.

8. A grinding machine as recited in claim 7, wherein the said first means is a cam-operated lever and a fluid motor.

9. A grinding machine as recited in claim 7, wherein the said second means is a fluid motor operating on the extension through a one-way clutch concentric with the extension and a rotatable plate having an operating handle and a central knob.

the said sliding motion to cause relative motion between the wheelhead table and the workhead transversely of the base to bring about a grinding operation, and

f. means operative at any time in the grinding operation to stop the rotation of the cam and move the wheelhead table to a dress position to bring the abrasive wheel into operative engagement with the dressing apparatus.

Claims

1. A grinding machine, comprising a. a base having a workhead mounted at one end, b. a wheelhead table mounted at the other end, c. a feed rod extending between the table and the base and being mounted in the table for longitudinal sliding motion relative thereto, and d. a rotatable cam mounted in the table for bringing about the said sliding motion to cause relative motion between the wheelhead table and the workhead transversely of the base to bring about a grinding operation.

5. A grinding machine as recited in claim 4, wherein a one-way clutch surrounds the feed rod, an arm extends radially from the exterior of the clutch, and a reciprocable fluid motor engages the outer end of the arm to produce incremental rotation of the rod to produce compensating sliding movement of the table relative to the base.

6. A grinding machine as recited in claim 1, wherein the feed rod is provided with a concentric piston which is slidable in a cylinder bore formed in the table, and wherein means is provided to introduce pressure fluid into the bore selectively on one side of the piston to produce dress retraction movemeNt of the table relative to the base or to the other for grinding.

7. A grinding machine, comprising a. a base, b. a table mounted on the base for sliding motion thereover, c. a feed rod extending between the table and the base and being mounted in the table for rotation and axial sliding motion relative thereto, d. a rod extension mounted in the table in alignment with the rod, e. a slidable connection between the feed rod and the rod extension to permit relative axial sliding movement between them but to cause them to rotate together, f. a first means mounted in the table to cause the sliding motion relative to the feed rod for grinding feed and for dress retraction movements, and g. a second means mounted in the table and surrounding the extension to cause rotation of the extension and the rod for producing compensation and adjusting movements of the table.

10. A grinding machine, comprising a. a base having a workhead mounted at one end, b. a dressing apparatus associated with the workhead, c. a wheelhead table mounted at the other end and carrying an abrasive wheel, d. a feed rod extending between the table and the base and being mounted in the table for longitudinal sliding motion relative thereto, e. a rotatable cam mounted in the table for bringing about the said sliding motion to cause relative motion between the wheelhead table and the workhead transversely of the base to bring about a grinding operation, and f. means operative at any time in the grinding operation to stop the rotation of the cam and move the wheelhead table to a dress position to bring the abrasive wheel into operative engagement with the dressing apparatus.