US2243371A - Internal grinding machine - Google Patents

Description

' a '27,194 1. H.L.Loo

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Patented May 27, 1941 2,243,371 INTERNAL GRINDING MACHINE Harold L. Blood, Worcester,

The Heald Machine Company,

Mass., assignor to Worcester, Mass.,

a corporation of Massachusetts Application April 5,1939, Serial No. 266,163

12 Claims.

The present inventionrelates to internal or bore grinding by the so-called chuckless or centerless-method, involving support and rotation of a hollow workpiece by rolling contact with its outer peripheral surface, so that the internal grinding operation generates a bore which is truly concentric with said outer surface. More particularly, the invention resides in a machine organization of this centerless type adapted especially to the handling and internal grinding of hollow workpieces having tapered or contoured (non-cylindric) outer peripheral surfaces.

Heretofore inthe centerless internal grinding of such non-cylindrichollow workpieces, the practice as disclosed for example in Cramer Patent No. 2,176,248, dated Oct. 17, 1939, has been to engage the work, for support and rotation thereof, in much the same manner as is customary in the centerless internal grinding of cylindric Work of uniform outside diameter,-using rolls or wheels having their axes substantially parallel to the grinding wheel and workpiece axes, and using a solidly-mounted thrust-resisting member for one end of the workpiece to bear against.

Such an arrangement has definite limitations, in that it is not readily adjustable to non-cylindric work of different sizes and of varying externaltapers or contours; one object of my invention is to overcome these difliculties.

A further object of my invention is to so arrange the thrust-resisting element of the centerless workholdin'g means that it not only promotes and assures the latters drive of the workpiece, but also serves'to compensate automatically for slight variations in external dimension that may presenting a succession or group of similar externally tapered workpieces to the machine, in such manner that their bores, despite such size variations, can be maintained in substantial axial alignment with the sizing gauge which is customarily employed and incorporated in such a machine.

Other and further objects and advantages, of the present invention will hereinafter more fully appear from the following detailed description with the accompanying drawings, in which- Fig. 1 is a front elevation of a machine embodying the invention, with parts broken away.

Fig. 2 is a larger scale plan view of the worksupporin'ng and work-rotating means.

' Fig. 3 is a sectional view substantially along Fig. 4 is a sectional view substantially along Fig. 5 is a fragmentary front elevation of a part of the work-supportingstructure.

Like reference characters refer to like parts in the different figures.

As shown in Fig. 1 the machine to which my invention is applied is a conventional type of internal grinding machine having the usual reciprocatory table i on which either the grinding wheel or the work to be ground is carried, the reciprocations of the table serving in either case to produce a relative translatory movement between the grinding wheel and the workpiece. In the machine shown, the table supports and carries a workhead 2 while the wheelhead 3 is mounted on a bridge 4 which spans the guide- Ways 5, Fig. 3, provided by the machine base 6 for the movements of the table I. The grinding wheel I is carried on a spindle 8 journalled' in the wheel head and is suitably rotated at a high rate of speed. The workpiece a, see also Figs. 2, 3 and 4, is 'adapted to-be rotated in grinding position by a centerless or chuckless work-holding arrangement provided by'the work-head, as will hereinafter appear.

The reciprocations of the table I which cause the rotating grinding wheel to make the desired traverse longitudinally, through the bore of the workpiece a, and which provide for an-axial separation between the wheel and workpiece, are imparted in any well known manner, as by the use ofthe table controlling and reversing mechaacter and need not be described indetail.

nism described in detail in the Blood and Burns Patent No. 2,027,627, dated January 4, 1936. This mechanism is not a feature of the present invention and need not be here described in detail.

The crossfeed movement between the work-- piece and the grinding wheel may be obtained by a transverse movement of the wheelhead 3 on the bridge 4. This crossfeed movement may be procured by ny well known means, as for example, the fluid pressure actuated crossfeed mechanism of the Blood and Burns Patent No. 2,027,627, above referred to. It is sufficient to note that a cross slide, not shown, carrying the wheelhead is horizontally movable on the bridge and is shifted by a crossfeed screw 9 which is rotated by a rack l0 reciprocated by a suitable fluid pressure actuated means.

The table I also carries a suitable truing or dressing tool II for the grinding wheel; the operation of this tool. is also conventional in char- 7 The illustrated machine also incorporates a well known form of gaging mechanism by which the grinding'operation on the bore of each suc-. M

threaded lug, not shown,

cessive workpiece a is automatically controlled, this gaging mechanism being substantially of the same type as that disclosed in the aforesaid Blood 2,027,627 and embodying,

suitable bracket I2, projecting upwardly from the table I for the slidable support of a gage rod I3 substantially in axial alignment with the workpiece a; it is sufficient to note for present purposes that the rod I3 carries gage members I4 and I5, slightly differing in diameter, which are urged yieldingly in the direction of the workpiece bore as the grinding operation thereon proceeds; when the workpiece bore is enlarged sufiiciently for the smaller of these gage members to enter it, there occurs automatically, as described in said Blood and Burns patent, dressing and truing of the grinding wheel by the tool II, following which the grinding operation is resumed until the larger of the gage and Burns Patent among other things, a

members can enter said bore, whereupon with the latter brought to the desired size, the grinding operation is discontinued.

The present invention provides a readily adjustable centerless or chuckless work-supporting means so arranged that the hollow work, regardless of variations in size, can be supported and rotated in substantial axial alignment with this gaging mechanism. The work-supporting and work-rotating elements are particularly adapted to workpieces having tapered or contoured external peripheries such as illustrated by the workpiece a in Figs. 1 and 2, the same representing the inner cone raceway member of a roller bearing.

having a frusto-conical outer surface with flanges at each end. For the centerless support .of such a workpiece, I provide, as shown in Figs. 2 and 3, the three adjustable elements I18, I1 and I8, adapted to engage with the frusto-conical surface of said workpiece. The element I8 is a driven rotary wheel or roll, for impanting rotation to the workpiece, and preferably engaging its outer surface substantially in opposition to the engagement of the grinding wheel I with the workpiece bore; the element I1 is arranged so as to provide, in cooperation with the element I8, 9. work-receiving throat; and the third element I8, is here shown as a pressure roll or wheel which, as hereinafter described, is held yieldably against the external tapered surface of the workpiece to retain the latter in said work-receiving throat.

The backing or regulating roll I8, Fig. 2, is mounted on the end of a spindle I80 journalled in a housing I8, and the spindle is driven from a motor 20, the pulley 2I of which is connected by a belt 22 to a-pulley 23 on the spindles I8a. The housing I! and motor 28 are mounted on a base plate 24 which is angularly adjustable on a pin 25, The pin 25 projects vertically from a slide 28 positioned beneath the base plate. This slide has guideways on the underside thereof engageable with corresponding transversely extending guides 21 on the table I. slide 28 transversely of the table is adjusted by means of a screw 28, Fig. 3, suitably held against endwise movement on the table and engaging a on the underside of the slide. The angular position of the base plate 24 is maintained, when once adjusted, by a clamping screw 28 in a lug 38 which extends upwardly from the slide and engages an arcuate surface 24' on the unders'de of the base plate.

As shown in Fig. 4, the supporting element I1 is carried by a block II in which it is vertically adjustable, being held in "adjusted position by a The position of the clamping screw 32. The block 3| is bolted to a small cross slide 33, the position of which, transversely of the table, is controlled by an adjusting screw 34,

The pressure roll I8 is journalled on a spindle I80. provided by a housing 35 mounted on a base plate 36. The latter is turnable on a pin 31 carried by a turntable 38, whose upper surface provides a support for the angular movement of said plate 38. The turntable 38 has an upwardly extending lug 38 'in which is positioned an adjustable screw 39 engageable bythe plate 38 to limit the movement of the pressure roll I8 toward the workpiece. This movement of the pressure roll against the workpiece surface is obtained by the coil spring 40 connecting the housing 35 to any suitable projection of the table I, and thus serving to yieldably draw the roll I8 against the workpiece. A handle provides for manual turning of the housing about the axis of the pin 31.

The angularity of the axis of the pressure roll I8 relative to the workpiece axis is adjusted by pivotal movement of the turntable 38 about a pin 42 carried.- by a slide 43 which is transversely adjustable on the table I. The slide 43 has an upwardly extending lug 43' having a clamping screw 45 which holds the turntable against turning movementrelative to the slide. The position of the slide 43 transversely of the table I is adjusted by means of a screw 48 held against endwise movement on the table I and engageable with a threaded portion, not shown, of the slide The above-described arrangement is readily adjustable so as to accommodate workpieces of different sizes and to hold and rotate them in axial alignment with the gaging mechanism of. the machine. This accommodation to different sizes of workpieces is obtained by operation of the screws 28 and 48 to procure inward movement or outward movement as desired of the slides 28 and 43 respectively; also by the vertical and horizontal adjustment provided for the element I'I. Additionally the elements I8 and I8 are both adjustmoveable to enable the respective axes of saidelements I8 and I8 to be brought into parallelism with those portions or elements of the workpiece surface which are engaged by the rolls or wheels I8 and I8. In this connection, it is to be noted that said wheels or rolls I8 and I8 tend to im'- part by their engagement with the tapered external workpiece surface, an endwise movement to said workpiece in one direction, for example, in the arrangement shown, to the right in Fig. 2. Heretofore, in the centerless internal grinding of hollow workpieces, this endwise tendency has been resisted by providing a solidly or rigidly mounted backing device adapted to be engaged by one end of the workpiece, saiddevice serving as a fixed stop to limit such endwise movement.

However, I have discovered that for workpieces having tapered!- external peripheries, it is most desirableto resist this endwise tendency by a tain the work in constant contact with the rolls -J I8 and- I8, but also serving as a means by which slight differences in size, encountered in a run or succession of similarly-dimensioned workpieces can be compensated for, in order to maintain ings are identical a description of either support will sumce for both.

Referring to Fig. 3, the finger 41 is carried by a member 49, being held in adjusted position therein by a clamping screw 50. The member 49 is turnable about a horizontal pin 5| in a block 52 mounted on the upper side of a slide 53. The slide 53 is longitudinally adjustable on a guide member 54 mounted on the top .of the table I. A coil spring 55 (see also Fig. 1) is positioned between the member positioned in recesses 55 and 51 in the member and block respectively. .The spring thus resiliently holds the finger 41 against the end of the workpiece. An adjustable screw 58, also positioned in the member 49, limits the turning movement of the member 49 under the action of the spring when no workpiece is in position in the work-supporting structure.

A member 49, corresponding to the member 49, supports the finger .41 and this member is carried by a block 52'. A threaded rod 59 in the slide 53 has left and right hand threads thereon, as shown in Fig. 2, for engagement with threaded lugs, not shown, on the blocks 52, and 52' respectively, and thus the rod provides for simultaneous movement of the fingers 41 and 41' toward or away from each other to-adjust the spacing of said fingers to workpieces of varying size.

To provide for a longitudinal adjustment of the slidle 53 the guide member has mounted therein a screw 60 which operatively engages a threaded lug, not shown, on the slide. By this arrangement it is, possible to adjust the position of the back rest or fingers 41 and 41' longitudinally of the table as a unit to accommodate various lengths of workpieces. The threaded rod 59, as

above stated, provides for adjustment of the two fingers 41 and 41' laterally of the table to accommodate various diameters of workpieces, this lateral adjustment being independent of the longitudinal adjustment of the fingers 41 and 41.

cession of similarly-dimensioned workpieces that for example, while the workpiece a shown in Fig. 2 may have the precise external diameter for which the apparatus is adjusted. another workpiece in the same run or series may 49 and the block 52, being.

- with the periphery of a workpiece and It frequently happens in the grinding of a sucone or more of said workpieces will be slightly 'off-size;

be slightly undersize externally,and this condition under ordinary circumstances would involve a slight shifting of the axis of rotation of said off-size workpiece, so that its bore would not align exactly with the gaging mechanism. However, this difliculty is overcomein the present instance by the yieldability of the thrustresisting members 41 and 41', the latter permitting such under-size workpiece to shift endwise, under the influence of the spring-urgedroll I8 until true axial alignment of said workpiece with the gaging mechanism is secured. In other words,

tation of the work, comprising a plurality of circumferentially-spaced elements engageable backing member engageable with an end surface of the workpiece, said backing member including spaced work-engaging elements adjustable to ward or away from each other to accommodate various sizes of workpieces. 4

2. In an internal grinding machine, a centerless or chuckless means for the support and rotation of the work, comprising a plurality of circumferentially-spaced elements engageable with the periphery of a workpiece and a yieldable.

backing member engageable with an end surface of the workpiece, said backing member including spaced work-engaging elements adjustable toward or away from each other to accommodate various sizes of workpieces, said backing member being also adjustable toward and away from the spaced work-engaging elements to accommodate various lengths of workpieces.

3. In an internal grinding machine, a center'- less or chuckless means for the support and rotation of the work, comprising a plurality of circumferentially-spaced rolls engageable with the periphery of a workpiece, means for adjusting each ofsaid rolls toward or away from the other, and a backing member engageable with an end surface'of the workpiece and comprising spaced parallel elements movable toward. or away from each other to accommodate various sizes of workpieces.

4. In an internal grinding machine, a centerless or chuckless means for the support and rotation of the work, comprising a. plurality of circumferentially-spaced rolls engageable with the periphery of a workpiece, means for adjusting each of said rolls toward or'away from the other,

each of said rolls being adjustable about an axis at right angles to the roll axis toaccommodate the rolls to a workpiece having a tapering outer surface.

5. In a machine tool, the combination'with a reciprocable gage adapted to enter the bore of a workpiece, of a work-supporting structure for supporting and rotating a workpiece in alinement with said gage, said structure comprising spaced rolls engageable with the periphery of the work-' piece and adjustable separately toward and away from the axis of the gage to accommodate different sizes of workpieces with each workpiece supported in precise alinement with the gage, a backing member engageable with an end surface of the workpiece to limit the endwise movement relative to the rolls, said backing membercomprising spaced elements adjustable toward and away from each other for accommodating different sizes of workpieces. g

6. In apparatus 01' the class described, centerless means for the support and rotation of ana yieldable nular workpieces having non-cylindrical outer surfaces during a machining operation on the bore thereof, said means comprising a plurality of spaced elements, at least one of which is a positive driven roll, all of said elements being engageable with the periphery of a workpiece in portions where the elements of the outer surface of the workpiece are convergent, the portions of the elements engageable with the workpiece corresponding in contour to the non-cylindrical portion of the workpiece surface, one of said elements being resiliently urged toward the others to assure an engagement between each of said elements and the workpiece, and a yieldable backing member engageable with an end surface of the workpiece away from which the elements are convergent, said backing member urging the workpiece endwise relative to the spaced elements until a flange on the workpiece engages with at least one of. said elements.

7. In apparatus of the class described, centerless means for the support and rotation of annular workpieces having non-cylindrical outer surfaces during a machining operation on the bore thereof, said means comprising a plurality of spaced rolls engageable with the periphery of a workpiece, a support cooperating with said rolls and also engageable with'the workpiece periphery, said rolls and support engaging the workpiece in a portion where the elements of the outer surface thereof are convergent, one of said rolls being resiliently urged toward the support and the other roll to assure an engagement between each of said rolls andthe workpiece and to hold .the workpiece against the support, the

portions of the rolls and the support which are engageable with theworkpiece corresponding in contour to the surface of the workpiece engaged thereby, and a yieldable backing member engageable with an end surface of the workpiece away from which the elements of the outer surface thereof are convergent, said backing member limiting the endwise movement of the workpiece resulting from the action of the rolls thereon.

8. In an internal grinding machine, a centerless or chuckless means for the support and rotation of hollow workpieces, each with a tapered external surface, said means including a plurality of circumferentially-spacedl rotary members for engagement with said tapered workpiece surface, means for gaging each workpiece bore during the grinding operation thereon, said rotary members being radially adjustable relative to said gaging -means to enable various sizes of workpieces to be supported and rotated thereby in substantial alignment with said gaging means, and means for resisting endwise movement of. the workpiece by said rotary members, said last-named means being spring-pressed against one end of the workpiece, whereby any workpiece varying slightly from the external size for which the rotary members are adjusted, may shift endwise in said centerless or chuckless means to maintain its alignment with saidgaging means.

9. In an internal grinding machine, a centerless or chuckless means for the support and rotation ofhollow workpieces each having a tapered external surface, said means including a plurality of cireumferentially-spaced rotary members for endwise movement thereof by said rotary members, and cooperating with said spring-pressed rotary member to procure such endwise shifting of a slightly oversize or undersize workpiece as will establish its axial alignment with said gaging means.

10. In an internal grinding machine, a centerless or chuckless means for the support and rotation of hollow workpieces having tapered external surfaces, said means including a plurality of cir- .cumferentially-spaced rotary members for engagement with the tapered workpiece surface, the axes of said members being substantially parallel with surface elements of said workpiece, a gaging device for the workpiece bore during the grinding operation thereon, means for adjusting said rotary members to the size and degree of taper of. a succession of similarly-dimensioned workpieces, to hold and rotate the latter in substantial alignment with said gaging device, and

yieldiable means for opposing endwise movement of such workpieces within said centerless or chuckless means, whereby the external taper of each workpiece allows any slightly undersize or oversize workpiece, by shifting endwise in said centerless or chuckless means, to maintain its axial alignment with said gaging device.

11. In an internal grinding machine, a centerless or chuckless means for the support and rotation of the work, said means including a plurality of circumferentially-spaced rolls engageable with the periphery of a workpiece, means for adjusting said rolls toward and away from each other, to

accommodate them to various sizes of workfor operation on the bore of a workpiece when the latter is supported and rotated by said rolls, and means engageable with an end surface of said workpiece for yieldably resisting the latters endwise movement by said rolls, said means maintaining said tapered surface in frictional contact with said rolls.

' HAROLD L. BLOOD.

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