US2962840A - Grinding apparatus - Google Patents

Description

Dec. 6, 1960 c. H. WERTH GRINDING APPARATUS Filed Sept. 19, 1957 2 Sheets-Sheet 1 INVENTOR. CARL H. WERTH ATTORNEYS FIG. 4

FIG. 2

FIG. 3

K?! (Fi Dec. 6, 1960 c. H. WERTH 2,962,840

GRINDING APPARATUS Filed Sept. 19, 1957 2 Sheets-Sheet 2 INVENTOR. CARL H. WERTH ATTORNEYS United States Patent GRINDING APPARATUS Carl H. Werth, Saginaw, Mich., assignor to Hoern &

Dilts Division of The Britain Machine Company, Saginaw, Mich., a corporation of Connecticut Filed Sept. 19, 1957, Ser. No. 684,952

11 Claims. (CI. 51-50) This invention relates to grinding apparatus of the type wherein a revolving grinding wheel is reciprocated axially in the bore of a revolving workpiece and sizing apparatus is employed to automatically retract the grinding wheel when the workpiece has been ground to size.

In my copending application, Serial No. 562,029, filed December 9, 1955, a high precision grinding machine is described which has a revolving tool which is fed radially an increment at a time into the bore of a revolving workpiece while it is making an axial pass across the surface of the workpiece, and sizing apparatus is described which operates in response to a predetermined separation of a pair of feeler arms to first automatically interrupt the radial feed of the tool at a predetermined size and thence to automatically withdraw the tool entirely when the actual finish size is reached. Some difliculty has been encountered with the sizing mechanism described in my previous application because the fine material ground off tended to work its way into the bearing on which the feeler arms were pivoted intermediate their ends and interfere with the operation of the apparatus, and also because the apparatus was not as accurate as desired even when the bearing was not clogged with grinding dust.

In production type grinding machines of the character described it is necessary in many instances that size be maintained to the ten thousandth of an inch and that the bore be absolutely concentric with its axis. The design of suitable sizing apparatus is also complicated by the fact that there is usually relatively little clearance to accommodate the feeler arms which are supported on the grinding spindle housing so that the sizing apparatus is withdrawn with the grinding wheel when the grinding operation is completed and another workpiece can be automatically indexed into position. In the prior application to which I refer feeler arms were shown which extended transversely to the axis of the grinding wheel to a point above the bore of the workpiece and these arms were provided with relatively elongated, dependent legs extending into the bore of the workpiece which had work engaging surfaces provided thereon. Because the dependent portions operated in a cantilever manner with offset forces applied to them, the feeler arms could be spread apart at their work engaging ends somewhat without affecting the relative position of the rear ends of the arms which in fact control the grinding operation.

One of the prime objects of the instant invention is to provide grinding mechanism of the type described with sizing apparatus of extreme accuracy wherein the work engaging inserts, the axis of pivot of the feeler arms, and the size interpreting surfaces are all in line so that the size interpreting surfaces are at all times in a relative position precisely correlated to the relative posirtion. of the work engaging inserts. With the inserts, axis of pivot, and size interpreting surfaces all in line there are no offset forces acting on the portions of the feeler arms which depend into the workpiece and spread of the work emaging surfaces does not cause the deflection of the depending portions as formerly. Further, with the cantilever eltect eliminated the tendency of the feeler arms (which engage the revolving workpiece) to chatter is avoided.

Another object of the invention is to provide an apparatus of the type described which does not employ means pivoting t-he feeler arms which are easily clogged by grinding dust.

A further object of the invention is to design sizing apparatus including means pivoting the feeler arms to the support which functions to urge the work engaging ends of the feeler arms toward the surface of the workpiece during the grinding operation.

Another object of the invention is to provide apparatus of reliable and practical design which is relatively economical to manufacture and assemble and promotes the low cost, precision grinding of workpieces on a quantity able, feeler arms having a true, sensitive motion free of vibration effects.

Still a further object of the invention is to design grinding apparatus with a sizing device which provides maximum access for the workholding chuck in the sense that the chuck has a maximum space available to grip the workpiece.

With the above and other objects in view the present invention consists in the combination and arrangement of parts hereinafter more fully described, illustrated in the accompanying drawings, and more particularly pointed out in the appended claims, it being understood that equivalent changes may be made in the various elements which comprise the invention without departing from the spirit thereof or the scope of the appended claims.

In the drawings:

Figure 1 is a side elevational view partly in section to show the grinding wheel and sizing apparatus in position inside the bore of a workpiece.

Figure 2 is a top plan view thereof taken on the line 22 of Figure 1. t

Figure 3 is a top plan view of the feeler arm biasing springs only.

Figure 4 is a fragmentary side view of one of the projecting inserts.

Figure 5 is a side elevational view illustrating a modified embodiment of the invention.

Figure 6 is atop plan view on the line 55 of Figure 5.

Referring now more particularly to the accompanying drawings wherein I have shown a preferred embodiment of the invention, a letter G generally indicates grinding apparatus which, except for the sizing apparatus which will be described, will be for convenience sake assumed to be identical in all respects with the grinding machine disclosed in the aforementioned application. In that application a completely automatic machine was described in the bore in an axial direction while simultaneously'be' ing radially fed into the bore an increment at a time. When a predetermined rough size was ground, the sizing workpiece so that a new workpiece could beindexed into position. It will be assumed for the "sa-ke bf convenience of disclosure that the apparatus is operating in identically the same manner and, accordinglyflonly the sizing apparatus which is em'ployedwill be described-"in detail.

In the drawings the grinding wheel: spindle housing bears the numeral 'a'nd has aguide slotor'opening 11 as in the aforementionedapplication which accommodates the guide portion 12a'of a'bracket13'which similarly has a stop portion 14 adapted to be engaged by a bracket on the stationary housing of 'the'machine to limit the descent of the sizing apparatus into the workpiece. When the spindle housing 10 is raised tolift the grinding wheel out of the bore of a workpiece the section 10a will, of course, come into engagement with the arm 12a and will lift the sizing apparatus outof the work piece in the same manner as inmy' prior application. Journaled in the spindle housing'10 is the'sp'indle 110 on which the grinding wheel 12 is mounted and in Figure 1 the grinding wheel 12 is shown in operative position in engagement with the bore of a workpieceW which is supported in position by a revolving chuck C.

The sizing apparatus which will now be describedis designed particularly with a view to extreme accuracy and has been found in tests to be more accurate and trouble free than the sizing apparatus described in my prior filed application. It will be readily observedthat it 'is a problem in the first instance to get sizing apparatus into the workpiece at all because of the relatively small clearance between the edge 15 of the spindle housing bearing and the edge 16 of the chuck or the workpiece as the case may be. The problem has been solved by providing a pair of feeler arms 17 and 18 which extend generally in a vertically inclined plane relative to' the axis of the grinding wheel and the axis of the bore of the workpiece. These arms 17 and 18 are supported from the bracket 13 by a post 19 which is releasably secured to the bracket 13 by bolts 20 and 21. Slots 22 provided in the bracket 13 permit an angular adjustment of the posts 19 about point 20 as a pivot and, of course,'when the bolt 21 is tightened down the post 19 is securely held in a particular position of adjustment. The lower end of post 19 is angularly disposed as at 19a so that it is generally normal to the general plane of extent of feeler arms 17 and 18 as shown.

Each arm 17 and 18 has an inwardly extending section 23 (Figure 2) and resilient, spring strips of relatively thin gage are employed to flexibly secure the arms 17 and 18 to the lower end 19a of the support bar 19. These springs 24, which'are preferably formed of a spring steel, pivotally secure the arms 17 and 18 to the post 19 in the sense that they flex to permit relative separation of the ends of the feeler arms 17 and 18 about the portions 24a of each spring as a pivot. When secured in place the spring strips 24 are in an unnatural," stressed condition'which causes them to urge the work engaging ends of the arms 17 and 18 outwardly at all times into work engaging relation with the bore of the workpiece W. The normal shape of spring 24' is illustrated in Figure 3 and the springs, which are not stressed beyond their elastic limit or set when mounted in the sizing apparatus,

would return to this shape if released. Screws 25 secure the springs 24 to the post 19 and also secure caps 26 in position so that the clamping forces exerted by screws 25 are spread out over a distributed area. Similarly screws 27 secure the spring strips 24 to the inner faces of the inwardly projecting sections 23 ofthe arms 17 and 18 and caps 28 distribute the clamping forces exerted by-screws 27 over larger areas of the spring strips. The

,Figure 1.

areas of pivot 24a are enlarged sufiiciently to furnish an unrestricted pivoting action by beveling the caps 26'and 28 as at 26a and 28a.

The main body portions of the feeler arms 17 and 18, from the point a to the ends of the arms remote from the grinding wheel, extend in a plane at an angle b with respect to the axis c of the-grinding wheel as shown in What may be termed the front or work engaging sections of the arms 17 and 18 comprise depending portions 17a and 18a. and laterally extending portions 17b and'lSb, which are curved outwardly'asat 17c'and 18c to accommodate the grinding wheel 12. "Diamond tipped work engaging inserts 29 are mounted on the portions 17c' and 'l8c-and carbidecam'inserts29a are fixed to portions 17c'and l8c below the-inserts 29 to protect inserts 29. Provided on inserts 29a are beveled surfaces 2% which tend to cam the feeler arms into compressed relation, when the arms are being moved down into the workpiece, and so operate to protect inserts 29.

The rear ends-of feeder arms 17 and 18 are provided with a flat surface 30 and a nozzle 31 which between them define an escape clearance d in the same manner as in my prior filed application and the nozzle 31 which has a port 32 connected'with a fluid pressure line 33 similarly leads to a pressure control system which continuously passes'air under pressure out the clearance a. Dependent on the width of clearance d the pressure inthe'system 33 is affected as described inmy prior application and the radial feed of the grinding wheel'may be interrupted or the grinding wheel and sizing apparatus may be withdrawn axially from the workpiece. An adjusting screw 34 threaded through feeler arm 17 provides the imperforatefiat surface 30 against which the stream ofair of the feeler arms be communicated to the rear ends of the arms in order to arrive'at the accurary which is required. Accordingly, it is extremely important to note that the portions 17b are of such length and the inserts 29 are so positioned that a line e drawn through the inserts 29 and nozzle 32 is perpendicular to theline' f designating the axis of pivot and preferably passes through substantially the center of the axis of pivot f. Ideally, the hardened inserts 29 will be so disposed that they are on line e which passes through the center of the pivot axis at 24a and the centers of the areas 30 and 31a as illustrated in Figure 1. This so-called in line arrangement preventsotfset forces from being applied to the front end sections 17a and 17b which would'tend-to deflect them without affecting or completely afiecting the relative position of surfaces 31a and 30.

A laterally disposed stop pin 35 is threaded ina'rm 17 adjacent the surfaces 30 and 31 and extends into the path of arm 18 so that the distancethe work engaging portions of the arms can spread is limited. 'Also, an angle plate or horn 36 which is secured to the support bar 19 by screws 37 has openings 38 of slightly larger diameter than pins 39 which limit the spread of the arms 17 and 18 and provide an additional safety factor. These stop pins 39 prevent the arms 17 and 18 from opening suificiently to set the flexible springs 24. As will be apparent the range of the sizing apparatus may typically be about a thirty-second of an inch. The openings 38 may'perrnit a movement of one-sixteenth of an inch and accordingly pin 35' is set within the range of surfaces 29b to protect the inserts 29. Pin 35 is set to limit the" spread of the arms 17 and 18 when they are outside the'workpiece so that they can spread only slightly beyond the finish size to'be ground and this permissiblespreadnor- It is believed unnecessary in this application to describe the electro-pneumatic system which connects to line 33 nor the mechanism which it actuates to interrupt the radial feed of the wheel or withdraw the wheel and sizing apparatus since these elements will be exactly as described in the foregoing application and will operate in exactly the same manner.

In operation any very slight spread of the portions 170 of the feeler arms 17 and 18 tends to close the clearance d, of course, and in so doing increase the pressure of the air in line 33. When a predetermined pressure is reached the feed of the grinding wheel 12 radially into the wall of the workpiece is halted and when a still higher pressure is reached the grinding wheel and sizing apparatus are lifted from the workpiece entirely. Actually, of course, the arms 17 and 18 pivot only very slightly and the springs 24 furnish a perfectly trouble free pivot at areas 24a which cannot be clogged with grinding dust and which are sufficiently resilient to return to original position when the arms 17 and 18 are lifted out of a finished workpiece, compressed to original position as described in the prior application referred to, and reinserted in a new workpiece. The arms 17 and 18 are continually urged outwardly and inserts 29 maintained in engagement with the bore of the workpiece by springs 24 as described previously. With the construction such that line e is normal to a line f through the axis of pivot cantilever bending of the front ends of the feeler arms forward of the springs 24 is not the problem it is with present gauges.

Because in the embodiment of Figures 1-4 the inserts 29, areas of pivot 24a, and size interpretation surfaces 30-3141 are all in line, there is no cantilever effect as formerly when the work engaging portions tended to wind up or deflect under the movement resisting pressures applied to inserts 29 without affecting the relative positions of the body portions of the feeler arms. Also this in line construction wherein an imaginary straight line down the sides of the feeler arms passes through the inserts 29, the pivotal areas 24a, and the size interpretation surfaces 30-31a tends to eliminate vibration and chatter resulting from the engagement of work engaging inserts 29 with the revolving surface on which the grinding wheel is operating. Since vibrations in cantilever constructions are proportional to the third power of the v length of the cantilever it should be clear that this result is very important to the precision of the sizing apparatus. The pressure exerted against surface 30 further creates no cantilever effect with the present design.

In Figures 5 and 6 I have shown very similar sizing apparatus which is adapted to the gauging of relatively inaccessible outer diameters. In the case illustrated, it is desired to grind the portion 40 of the workpiece W which is rendered dilficult because of the portion 41 of the workpiece. A chuck (not shown) similarly revolves the workpiece W in the same manner as previously described. The arms 17 and 18 are connected to the posts 19 as described previously and the difference is in the shape of the work engaging ends of the feeler arms 17' and 18' which instead of extending substantially lineally to the surface of the workpiece substantially directly in line with them have laterally extending curved portions 42 which cross over to engage the opposite surface of the workpiece. Also, the portions 42 do not include any vertically dependent sections but rather depend at an angle as indicated in Figure 5. The effect of this design is to provide a scissors construction with the springs 24 operating in the same manner to urge the inserts 29' into engagement with the peripheral wall of the workpiece at all times. The sizing apparatus similarly, of course, includes a nozzle 31 and an adjusting screw 34 defining the clearance d, the nozzle being connected to line 33 as before. Also the springs 24' are secured to the arms 17' and 18' and support bar 19' in exactly the same manher as before and the stop pin 35 is provided. It will be seen that inserts 29', portions 24a of the springs 24 and size interpretation surfaces 30 and 31a, are all in line as previously on the imaginary line e which is again drawn to illustrate this relationship. In order to avoid the portion 41 of the workpiece W the arms 17' and 18' are presented to the surface 40 at an inclined angle b' relative to the axis of the grinding wheel 12 or axis of the portion 40. The operation of the sizing apparatus described in Figures 5 and 6 is, of course, identical with the operation of that described in Figures 1-3 and no further discription is believed necessary.

It should be apparent that I have perfected sizing apparatus which is ideally suited to the grinding operation described and is so accurate that tolerances of less than a ten thousandth of an inch may be held if desired. In both embodiments the springs 24 and 24' provide virtually frictionless hinges which will permit operation of the system with low pressures in the neighborhood of 2 to 3 p.s.i. if desired. It is to be understood that various of the operating parts may be replaced by equivalent elements and in all cases the drawings and descriptive matter are to be regarded as illustrative of the invention rather than as limiting the same in any way.

I claim:

1. Grinding apparatus comprising; a grinding head carrying a reciprocable grinding wheel for reciprocating travel relative to workpiece arranged in generally axially parallel disposition with said wheel; a support post on said grinding head, a pair of generally parallelly arranged feeler arms having work engaging surfaces in embracing relationship with the wheel when the wheel and arms are in engagement with the diameter of a workpiece; spring strip means extending in the general plane of the arms toward the workpiece connected between said arms and post, said means being deformed out of normal shape to urge said work engaging surfaces into engagement with the diameter of a workpiece; and means on said arms for actuating a machine control in response to the relative position of the work engaging surfaces.

2. Work sizing apparatus operative in response to a predetermined diameter of a workpiece to automatically control a grinding operation comprising; a pair of generally parallelly arranged feeler arms; a support, spring strip means extending in the general plane of the arms toward the workpiece connected to said arms at one end and said support at the other mounting said arms intermediate their ends for relative separation and return of their ends, said strip means being normally shaped to hold work engaging surfaces on said arms in engagement with the workpiece; and means on said arms for actuating a machine control in response to a predetermined relative position of the work engaging surfaces.

3. Work sizing apparatus operative in response to a predetermined diameter of a workpiece to control a grinding operation comprising; a pair of feeler arms pivotally connected intermediate their ends; said feeler arms at one end being adapted to engage the bore of a workpiece and carrying at a point remote from said end means for actuating a machine control in response to the relative position of the work engaging ends; the feeler arms except at their work engaging ends extending substantially in a general plane of extent and at their work engaging ends having portions depending angularly out of the said plane of extent to extend from above the workpiece into the bore thereof and portions extending laterally therefrom to dispose the work engaging points in the said general plane of extent in the line of the axis of pivot thereof.

4. Work sizing apparatus operative in response to a predetermined diameter of a workpiece to control a grinding operation comprising; a pair of feeler arms extending generally in a plane at a relatively great acute inclined angle to the vertical having spaced apart work engaging portions at one end for engaging the bore of a workpiece; means mounting said arms which permits the work engaging portions of said arms to separate one from the other; means for actuating a machine control in response to the relative position of the work engaging portions provided on said arms; the feeler arms near their work engaging ends having portions depending from the general vertically inclined plane of extent of the arms at an obtuse angle relative thereto to extend down to the surface of the workpiece to bemeasured, and portions extending laterally from said depending portions on which the work engaging portions are disposed in the general plane of extent of the arms.

5. Grinding apparatus comprising; a grinding head carryingan axially reciprocable grinding wheel for reciprocating travel in the bore of a workpiece arranged in generally axial disposition with said wheel; a support post on said grinding head; a pair of feeler arms extending generally toward the grinding wheel in a plane at a relatively great acute angle relative to the axis of the grinding wheel; work engaging surfaces on the ends of said arms adjacent the grinding wheel; means pivotally connecting said arms to said support post so that their ends are relatively separable; means on said arms for actuating the grinding wheel operated in response to the relative separation of the work engaging surfaces; said ends of the feeler arms adjacent the grinding wheel including portions extending from the remaining portions of the arms generally parallel to the axis of the grinding wheel; and portions thence extending generally transversely to the axis of the grinding wheel on which the work engaging surfaces are provided disposing the work engaging surfaces in the general plane of extent of the said remaining portions of the feeler arms.

6. The combination defined in claim in which said means pivotally connecting the arms to said support post comprises a pair of flexible resilient strips joining each of said arms to opposite faces of said post and prestressed to urge said arms into work engaging relation.

7. The combination defined in claim 5 in which said means on said arms operated in response to the relative separation of said work engaging surfaces comprise a nozzle at the outer end of one of said feeler arms, a fluid pressure system in communication with said nozzle, and a surface on the other arm opposite said nozzle defining an escape clearance between said nozzle and surface whose width varies the pressure of the fluid in said system.

8. Grinding apparatus comprising; a grinding head carrying an axially reciprocable rotary grinding wheel for reciprocating travel in the bore of a workpiece adapted to be arranged ingenerally axially parallel disposition with said wheel; a support post on said grinding head; a pair of generally parallel feeler arms extending toward the grinding wheel at an acute angle relative'to the axis of the wheel; said arms having curved work engaging front ends partially surrounding said wheel when the wheel and arms are disposed in a workpiece; the front ends including portions adapted to depend into the bore of a workpiece from above and portions extending laterally therefrom; work engaging inserts projecting outwardly from said latter portions adapted to extend into engagement with the workpiece; oppositely disposed sections having flat surfaces parallel to the plane of extent of the arms on each arm; thin gauge, spring steel strips on opposite sides of said post connected at one end to the said surfaces of said sections and at the other end to opposite sides of said post to pivotally mount said arms for relative separation and return of the ends of the arms; a nozzle in the rear end of one arm connected to a fluid pressure control system extending out of the inner surface thereof; and an adjusting member in the other arm having a fiat surface opposite the nozzle to define a regulated escape clearance therebetween which varies with the relative position of the work engaging inserts to vary the pressure of the fluid in the said system; the inserts, spring strips, and nozzle and member surfaces being all bisected by an imaginary line drawn on the side of one of the feeler arms as described in the specification.

9. The combination defined in claim 8 in which a stop screw extends through one feeler arm toward the inner surface of the other arm.

10. The combination defined in claim 8 in which cam ming inserts extend from the portions from which said work engaging inserts extend below said work engaging inserts, but extend a slightly less distance.

11. The combination defined in claim 8 in which a horn mounted on said post has spaced openings therein; and pins depending from said arms and of less diameter than said openings extend into said openings.

References Cited in the file of this patent UNITED STATES PATENTS 987,942 Bariquand Mar. 28, 1911 1,225,858 Raule May 15, 1917 2,779,140 Saives -Jan. 29, 1957 OTHER REFERENCES Bigelow, Tooling and Production magazine, May 1956, pages 89-92, vol. 22, No. 2 (page 91, Fig. 3,'relied on).

UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,'962 84O December 6, 1960 Carl H. Werth It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the grant lines 2 and l2 and in the heading to the printed specification lines 3 and 4, for "Hoern 81 Dilts Division of The Britain Machine Company", each occurrence, read Hoern 81 Dilts Division of The New Britain Machine Company Signed and sealed this 2nd day of May 1961.

( SEAL) Attest:

ERNEST W. SWIDER DAVID Lo LADD Attesting Officer Commissioner of Patents

Images