US3916576A

US3916576A - Grinding machine

Info

Publication number: US3916576A
Application number: US368631A
Authority: US
Inventors: Alfred T Blackburn; Herbert R Uhtenwoldt
Original assignee: Cincinnati Milacron Heald Corp
Current assignee: Cincinnati Milacron Heald Corp
Priority date: 1973-06-11
Filing date: 1973-06-11
Publication date: 1975-11-04
Anticipated expiration: 1992-11-04

Abstract

A grinding machine having a gage with a digital readout.

Description

i United States Patent Blackburn et al. Nov. 4, 1975 [5 GRINDING MACHINE 1,928,457 9/1933 Mershon 5l/165.74 x 2,010,706 8/1935 Williams.... 5l/l65.72 x [75] Inventors- Alfred Blackburn West Boylston; 3,603,044 9/1971 Price 51 /165.91 Herbert Uhte'lwoldt, Worcester 3,690,072 9/1972 Price 51/165.91 both of MBSS- 3,728,826 4/1973 Wada 51/l65.88 x

[73] Assignee: Cincinnati Milacron-Heald Corporation, Worcester, Mass. Primary Examiner-Harold D. Whitehead [22] Flled: June 1973 Attorney, Agent, or FirmNorman S. Blodgett; Gerry [21 Appl. No.: 368,631 8 [52 US. Cl. 51/165.74; 5l/l65.91 [51] Int. Cl. B24B 49/04 58] Field of Search 51/165 R, 165.72, 165.74, [57] ABSIRACT 51/165.88, 165.91, 165.93 A grinding machine having a gage with a digital read- References Cited out. UNITED STATES PATENTS 1,919,615 7/1933 Booth 51/165,91 7 Claims, 5 Drawing Figures US. Patent Nov. 4, 1975 SheetlofS 3,916,576

(Emmi FIG. I

Sheet 2 0f 5 3,916,576

U.S. Patent Nov. 4, 1975 U.S. Patent Nov. 4, 1975 Sheet 3 of5 3,916,576

US. Patent Nov. 4, 1975 Sheet 4 of5 3,916,576

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US. Patent Nov. 4, 1975 SheetS 0f5 3,916,576

FIG. 5

GRINDING MACHINE BACKGROUND OF THE INVENTION In the operation of grinding machines, particularly of the type used in the toolroom, it is necessary when finishing a surface of revolution to stop the machine and measure the size of the finished surface from time to time. This is particularly true in the situation where the operator divides the grinding operation into several parts, such as, rough grind, finish grind, and spark-out, as is sometimes necessary in order to obtain a suitable surface finish and taper, as well as removing certain out-of-round conditions. Not only does the stopping of the machine to measure the workpiece constitute a complete waste of operators time, but, under many conditions, the resulting product is not ground satisfactorily. Attempts to obtain a reading of the size of the workpiece by a gage in the workpiece during the grinding operation have been made with relatively unsatisfactory results. For one thing, the indication of size has always been difficult to read, so that, in order for the operator to make best use of a continuous sizing of a workpiece, it is necessary that the visual size indication be instantly readable. This is so that he can make changes in the cycle very quickly, as, for instance, in switching from rough grind to fine grind and from finish grind to spark-out, etc., as well as in terminating the grinding operation when final size has been reached. These and other difficulties 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 readily readable size indication.

Another object of this invention is the provision of a grinding machine having an in-process gage which reads workpiece size very accurately.

A further object of the present invention is the provision of a grinding machine having a workpiece gage which is operative under adverse conditions without detriment to the gage.

It is another object of the instant invention to provide a grinding machine having an in-process gage which is relatively simple in construction and which is capable of a long life of useful service with a minimum of maintenance.

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 set forth in the specification and covered by the claims appended hereto.

SUMMARY OF THE INVENTION In general, the invention consists of a grinding machine for finishing the surface of revolution on a workpiece, wherein the grinding machine is provided with a base on which is mounted a workhead with means for holding the workpiece and rotating it about the axis of the surface of revolution. A gage bracket is mounted on the workhead and a gagehead is mounted on the bracket. The gagehead has a finger which engages the surface of the workpiece. The gagehead is movable in a first mode relative to the bracket, due to changes in the radial distance between the surface of the workpiece and the axis. Means is operative to cause relative movement in a second mode between the gagehead and the bracket to re move the finger from the workpiece on occasion. A transducer is mounted to receive the move- 2 ment in the first mode and to convert it to digital pulses. A counter is provided having a visual readout. The counter receives the pulses from the transducer and produces a continuous algebraic summation which appears in the visual readout.

BRIEF DESCRIPTION OF THE DRAWINGS The character of the invention, however, may be best understood by reference to one 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,

FIG. 2 is a plan view of a portion of the machine,

FIG. 3 is an end elevational view of a portion of the machine viewed along the line III-III of FIG. 2,

FIG. 4 is a vertical sectional view of a portion of the machine taken on the line IVIV of FIG. 2, and

FIG. 5 is a sectional view of the machine taken on the line V-V of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, which best shows the general features of the invention, the grinding machine, indicated generally by the reference numeral 10, is shown as having a base 11 on one end of which is mounted a workhead l2 and on the other end of which is mounted a wheelhead 13. Means is provided in the well-known manner on the workhead to hold a workpiece and rotate it about the axis of a surface of revolution which is to be ground. A wheelhead is provided with a spindle on the end of which is mounted an abrasive wheel for finishing the surface of revolution. The grinding cycle takes place because means is provided for sliding the workhead 12 and the wheelhead l3 longitudinally and transversely of one another. Mounted at the rear of the base 11 is a control box 14 and on the front of the workhead is mounted a gage apparatus 15. A bracket 16 forms part of the apparatus and is bolted to a flange l7 welded to and extending forwardly from the main body of the workhead 12. A digital display 18 is also mounted on the workhead l2 and connected to the gage apparatus 15 by a cable 19.

FIG. 2 shows the manner in which the bracket 16 is provided with a longitudinal slot 21 to permit adjustment. The gage apparatus 15 is provided with a gagehead 22 which is connected to the bracket 16 for hinged movement about a vertical axis provided by a hinge shaft 23. Fastened to the inner part of the gagehead is a finger 24 having a hardened metal contact element 25 adapted to engage the surface of the workpiece 26. For the purpose of illustration, the workpiece 26 is shown as an annular element such as, the inner race of a ball bearing whose inner surface 27 is to be finished by an abrasive wheel 28.

The gagehead 22 consists of a first part 29, which carries the finger 24, and a second part 31 which is connected to the bracket 16. The first part 29 consists of two

parallel plates

32 and 33 joined by two

parallel rods

34 and 35. Extending between the plate 32 and the second part 31 of the gagehead is a flexible bellows 36, while a similar bellows extends between the plate 33 and the other side of the second part. An adjusting knob 38 overlies the hinged shaft 23 and is provided with a concentric scale 39.

A spiral spring 41 is shown attached at one end to a pin 42 on the gagehead and a pin 43 on the bracket 16. The line of action of the spring extending on one side of 3 the axis of hinge shaft 23 to provide for over-center action.

FIG. 3 shows the apparatus as it is viewed axially of the surface of revolution 27 in the workpiece 26. The apparatus is shown in a slightly inclined condition with the adjusting knob 38 extending from the upper portion of the second part 31 and the rod 35 inclined. Extending from the bottom of the apparatus is shown the coil spring 41 and the

pins

42 and 43 to which it is attached.

FIG. 4 shows the detail of the hinge, including the hinge shaft 23, which is fixed to a tongue 44 extending from the bracket 16. The second part 31 of the gagehead 22, is provided above and below the tongue 44 with

roller bearings

45 and 46 rotatably mounted on the ends of the shaft 23. Overlying the hinge shaft 23, the knob 38 is associated with a ratchet clutch 47 which assists in defining the limit of swing of the gagehead 22 relative to the bracket 16 to determine the inner position of the finger 24. One half of the clutch 47 has a radial abutment 48, while the other has an adjustable stop screw 49. The coil spring 51 keeps the two halves of the clutch together until they are lifted apart by the knob 38 and turned relative to one another to change the relative angular positions of the abutment 48 and the screw 49.

Extending between the two

plates

32 and 33 is a glass scale 52, whose face is accurately marked with spaced parallel lines extending transversely at the scale. Mounted in the second part 31 of the gagehead is a gagehead 53, formed with a slot 54 through which this scale 52 slides. A coil spring 55 serves to bias the first part 29 relative to the second part 31.

FIG. shows the manner in which the scale 52 is mounted in the

plates

32 and 33. The markings on the scale are not shown, since they are too fine to be represented well in a drawing.

The operation of the present invention will now be readily understood in view of the above description. The grinding machine is placed in operation with the workpiece 26 rotatably carried on the workhead l2 and the abrasive wheel 28 rotating on the wheelhead 13. The workhead and the wheelhead are moved relative to one another to bring the abrasive wheel 28 into engagement with the surface 27 of the workpiece in the usual manner to provide a grinding cycle. As the grinding progresses, the distance between the axis of the surface of revolution 27 and its surface increases. The gagehead 22 is rotated about the hinge shaft 23 to bring the finger 24 with its contact element 25 into engagement with the surface 27. The condition of spring 41 is over-center of the axis of the hinge shaft 23 so as to bias the gagehead in the counterclockwise direction; as observed in FIG. 2. At the same time that the finger 24 engages the workpiece, the stop screw 49 engages the abutment 48 to limit the rotation of the gagehead relative to the bracket 16. The spring 55 pulls the first part 29 of the gagehead forwardly of the machine relative to the second part 31 of the gagehead. Motion in this direction, however, is prevented by the engagement of the finger 24 with the surface 27 of the workpiece. As the grinding operation proceeds, however, the surface 27 moves forwardly and allows the finger 24 with the first part 29 of the gagehead to move forwardly of the machine. It also moves in that direction relative to the second part 31 of the gagehead. This causes the scale 52 to move through the slot 54 in the reading head 53 and produce electrical pulses due to the photoelectric scanner built into the reading head. The pulses are passed through the cable 19 to the digital display 18 and it is possible to read the position of the surface 29 of the workpiece directly to 0.001 inch. The operator, by observing the position of the surface which is to be ground on the digital display 18, is able to make suitable changes. As soon as a finished size is reached, for instance, he will stop the driving operation and rotate the gagehead 22 in a clockwise direction (as observed in FIG. 2) thus drawing the finger 24 out of the bore in the workpiece. As soon as the gagehead is moved clockwise far enough, the spring 41 goes over-center on the other side of the axis of hinge shaft 23 and pulls the gagehead even further to an inoperative position. In that position it will be out of the way of the operator so that he can change workpieces, etc., in the machine.

In a practical embodiment of the invention, the scale 52 and the reading head 53 form a linear encoder manufactured by Dynamics Reasearch Corporation of Massachusetts under their catalog designation LMS-IOO. This particular apparatus gives up to 50 micro inches per foot in accuracy and resolutions up to 20,000 counts per inch. It is a non-contacting apparatus so that no mechanical wear exists and continued accuracy is assured. Furthermore, its speed is very high since it measures at rates up to 50 inches per second. More specifically, the resolution in micro inches is 100, the scale accuracy in micro inches per foot at 68F is 100. It uses a reading head designated by their catalog L-3 and a scale designated by their catalog 15-100. The

scale is provided with 1,250 lines per inch. Electrically it has a two-channel output with a 3.5 volt square wave. The output impedance is 210 ohms and the input power requirements are +5.5 volts DC at 250 micro amps and 5.5 volts DC at micro amps.

The reading head generates 2,500 cycles per inch and the display 18 includes a pulse logic counter designated by the catalog designation X4. The coefficient of expansion of the glass which forms the scale 52, is matched to that of steel to reduce the effect of temperature change as much as possible.

Some of the advantages of the present invention will be readily understood from the reading of the above material. Certainly it assists in producing a drastic reduction in machine set-up time. It makes it possible, particularly in a toolroom grinding machine, to main-, tain accuracies in bores and spherical diameters to 1 to 10 thousands of an inch. The operator refers directly to the read-out display while grinding, so that the operation is faster and thus liable to error. It is possible for semi-skilled operators to exploit the full potential of the grinding machine and achieve the same standards of speed and accuracy as previously obtained only by skilled machinists. Since the size of the workpiece is continuously displayed, the operator is able to rough grind, finish grind, and spark-out without having to stop the machine to measure the bore.

It is obvious that minor changes may be made in the form 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 1. A grinding machine for finishing a surface of revolution on a workpiece, comprising a. a base,

b. a workhead mounted on the base and having means for holding the workpiece and rotating it about the axis of the said surface of revolution, 0. a gage bracket mounted on the workhead,

agagehead mounted on the bracket and having a finger to engage the said surface of the workpiece, the gagehead being movable in a first mode relative to the bracket due to changes in the radial distance between the surface of the workpiece and the said axis, the gagehead being mounted on the bracket for pivotal movement about a transverse axis with an over-center spring which is operative between the head and bracket to hold them either in a first position in which the finger engages the workpiece or in a second position in which the finger is removed from the workpiece a substantial distance, e. means operative to cause relative movement in a second mode between the gagehead and bracket to remove the finger from the workpiece, f. a transducer mounted to receive the movement in the first mode and convert it to digital pulses, and a counter having a visual readout, the counter receiving the pulses from the transducer and producing a continuous algebraic summation which appears in the visual readout.

2. A grinding machine as recited in claim 1, wherein the gagehead consists of a first part which carries the 6 finger and a second part that is carried on the bracket, the first and second parts being mounted for relative sliding movement in the said first mode.

3. A grinding machine as recited in claim 2, wherein a pair of parallel rods extend from one of the parts of the gagehead through bores formed in the other part to provide for the said relative sliding movement.

4. A grinding machine as recited in claim 2, wherein the transducer has two elements adapted to be moved relative to each other, one of the elements being fixed to the first part of the gagehead and the other element being fixed to the second part.

5. A grinding machine as recited in claim 4, wherein one of the elements of the transducer is an accuratelyruled elongated glass scale and the other element is a reading head having photoelectric means to generate pulses as the scale moves by it.

6. A grinding machine as recited in claim 5, wherein the reading head has a slot through which the scale is guided during the said relative movement.

7. A grinding machine as recited in claim 5, wherein a bellows extends from one end of the scale to a facing side of the head and another bellows extends from the other end of the scale to another facing side of the head, so that no foreign matter can gain access to the operative surfaces of the scale and head

Claims

1. A grinding machine for finishing a surface of revolution on a workpiece, comprising a. a base, b. a workhead mounted on the base and having means for holding the workpiece and rotating it about the axis of the said surface of revolution, c. a gage bracket mounted on the workhead, d. a gagehead mounted on the bracket and having a finger to engage the said surface of the workpiece, the gagehead being movable in a first mode relative to the bracket due to changes in the radial distance between the surface of the workpiece and the said axis, the gagehead being mounted on the bracket for pivotal movement about a transverse axis with an over-center spring which is operative between the head and bracket to hold them either in a first position in which the finger engages the workpiece or in a second position in which the finger is removed from the workpiece a substantial distance, e. means operative to cause relative movement in a second mode between the gagehead and bracket to remove the finger from the workpiece, f. a transducer mounted to receive the movement in the first mode and convert it to digital pulses, and g. a counter having a visual readout, the counter receiving the pulses from the transducer and producing a continuous algebraic summation which appears in the visual readout.

2. A grinding machine as recited in claim 1, wherein the gagehead consists of a first part which carries the finger and a second part that is carried on the bracket, the first and second parts being mounted for relative sliding movement in the said first mode.

5. A grinding machine as recited in claim 4, wherein one of the elements of the transducer is an accurately-ruled elongated glass scale and the other element is a reading head having photoelectric means to generate pulses as the scale moves by it.

7. A grinding machine as recited in claim 5, wherein a bellows extends from one end of the scale to a facing side of the head and another bellows extends from the other end of the scale to another facing side of the head, so that no foreign matter can gain access to the operative surfaces of the scale and head.