US2046261A - Grinding apparatus - Google Patents

Description

Juneso,1936. y J -GREN` 2,046,261

GRINDING APPARATUS vFiled Feb. 6, 1936 Patented Juneff30, 1936 GBINDING APPARATUS Clarence J. Green, Worcester, Mass., assignee to Norton Company, Worcester, Mass., a -corporal tion of Massachusetts VApplication'February 6, 1936, Serial No. 62,661 Y As claims. (ci. 511o1) 'I'his invention relates to grinding machines, and more particularly to an apparatus for grinding a work piece of non-circular cross section.

It is an object of this invention to provide a simple and thoroughly practical grinding ap-v paratus for grinding a work piece to a non-circular shape. It is another object of this invention to provide such a grinding apparatus which is simple, rugged and compactin constructionv 1o and simple in operation and use.

It is a further object of this invention tc provide a grinding apparatus for grinding a work piece of non-circular cross section in which the work piece is oscillated toward and from the l5 grinding wheel by means of a rotatable cam. A further object of this invention is to provide a grinding'apparatus of this type with a cam for oscillating the work piece which is adjustable so as to permit varying the shape of the work piece being produced.

It is a further object of this invention to provide a piston grinding attachment for grinding an oval or elliptical surface on the periphery of a work piece, such as a piston. It is a further object o'f this invention to provide a piston grinding attachment which is portable in structure and may be readily mounted on a standard cylindrical grinding machine. Other objectsv will be in part obvious or in part pointed out hereinafter.

'I'he invention'acordingly consists in the featur s of construction, combinations of elements, e. d arrangements of parts, as will be exemplifled in thestructure to be hereinafter described, and the scope o f the application of which will be lnj dicated in the following claims.

In the accompanying drawing, in which is shown one of various possible, embodiments of the mechanical features of this invention,

attachment in 'operative position thereon;

Fig. 2 is a longitudinal vertical section through the grinding attachment;

Fig. 3 is a cross sectional view, taken approximately'on the lineV 3-,3 of Fig. 2; Fig. 4 is a fragmentary sectional view, sho ing a modification of the arrangement shown-ln Fig. 3; and

Fig. 5 is a fragmentary plan view of theattachment, as shown in Fig. 2. l

A cylindrical grinding. machine has been illustrated in` the drawing, comprising a base. l0

which` supports a longitudinally reciprocable work table Il on the usual flat and V-ways- (not Wheel. 25.

Fig. 1 is a fragmentary front elevation of a 4 grinding machine showing the improved grinding and the rack-` bar 30 so that the table Il may be shown). The longitudinally reciprocable table II is provided with a rotatable work, support, comprising a motor driven headstock I6 and a footstock l'l which serve to support the attachment I8 in operative position on the ma' 5 chine. l,

A rotatable grinding wheel 20 is supported on a rotatable wheel spindle (not shown) which is in turn supported on a wheel slide 22. The wheel slide 22 is arranged to slide transversely on the 10 l base I0 on a pair of spaced slidewaysv (not shown). The wheel slide 22 is varranged to be moved transversely relative to the Vbase l0 by means of a. suitable wheel feeding mechanism. This mechanism maybe of any wellknown type, l5 such as for example vthat shown in the prior United States Patent to Norton No. '762,838 dated June 14, 1904. This mechanism has not been shown in detail in the present case, since .it is not considered part of the present invention. For details of disclosure, reference maybe had to the above-mentioned patent. A rotatable handA wheel 25 is mounted on the front of the machine base and is operatively connected to rotate a feed screw (not shown) 'to cause the'wheel-20 and wheel slide 22 to be moved transversely to- Y ward or from the work supporting table Il, depending on the direction of rotation of the feed In the construction illustrated in the draw-.- 30

ing, the work supporting table is arranged to be reciprocated longitudinally .relative to the` base I D and the grinding wheel 20 to traverse a work piece to be ground past the operative face of the grinding wheel 20. The table il is provided with a depending rack bar 30 by whichthe table may be traversed bya manual or power traverse mechanism, such as that shown in the prior patent above referred to. 'I 'his mechanism has not been shown in detail, since it is not considered part of the presentinvention. Reference may behad toithe 'above-mentioned expired patent for details of disclosure. A gear 3| meshes with the ,A rack 30 and is mounted on a rotatable shaft 32V which 'may `be rotated manually by means of ka gear 33 mounted on the outer end of a shaft 32. A manually operable traverse wheel 36 is mounted on the outer end of 'a shaft 34 Vand is connected by a gear 35 to rotate the gear 33, the gear 3l traversed.v longitudinally when desired.

The table I I may be reciprocated longitudinally by a power operated mechanism, such as,- shown in .the prior patent above referred to., This mechanism may comprise a rotatable power 55 driven shaft which is driven by means of a multiple speed drive. contained within a casing Il, details of which have not been shown in the present case since they are not considered part of the present invention. For details of this mechanism, reference may be had to the abovefrequently necessary to grind either a portion of the lpiston or the entire outer surface ofA the piston to an oval or elliptical form. It is desir. able to provide a grinding apparatus which is arranged' to oscillate the work supporting spindle toward and vfrom the grinding element so as to produce the desired oval or elliptical periphery on the piston or work piece being ground.. For a production grinding machine, such an apparatus may be built into the machine as a permanent part of the grinding machine. In repair shop work, however, it is frequently necessary for theshop to be equipped with grindingapparatus suitable for grinding the various replacement parts of the automobile to accurately fit in place of the part being replaced. For example,

when an automobile cylinder becomes worn orthe piston becomes worn, it isnecessary to replace the piston and to provide a piston which accurately its the worn cylinder. It is, therefore, desirable that the'piston grinding apparatus be provided as an attachment which may be readily applied to and utilized on a standard Y cylindrical grinding machine.

The improved piston grinding attachment fcomprises' a supporting member or'shaft 56 having conically shaped center holes 5I and 62 on `opposite ends thereof which are arranged to be supported by a headstock center 56 and a footstock center 56. 'I'he bar 56 supports a pair of spaced brackets V56 and 51. Each of these brackets is provided with cylindrical bores'which ilt upon the bar. The brackets 66 and 51 are held in a iixed position on the bar 56 by means of pins 56 and 59.V The upper ends of the brackets 66 and 51 are provided with bearings 66 and 6|, respectively, which serve to rotatably support a work spindle 62., A work holding and centering plate 64 is mounted on one end of the spindle 62 and is provided with a shoulder 65 which is adapted `to ilt within the open end od a work piece, such as a piston 66. The'shoulder 66 serves .to center the piston '66 with relation to the axis of rotation of the spindle 62 and also serves to locate the piston endwise. 'I'he piston 66 is arranged to be clamped rigidly in position on the plate' 66 -by means of a clamping mechanism comprising a pin 61 passing through the holes 66-and 66 in the piston 66. 'I'he pin 61 also passes, through a hole 16 in an enlarged head'1l Iof a clamping rod 12. 'I'he rod 12 is held against rotation by means of akey 16, fixed to the plate 64, which engages a keyway 14 in the rod 12 so that the rod is held against rotation but may Slide endwise. 'I'he rod 12 passes through a central aperture 15 within the'spindle 12 and ha: a reduced portion 16 which extends through .1 ne

" entirel length of the spindle 62. The end of the portion 16 is provided'with a screw thread 1,1 which is engaged by a manually operable nut 16. The workpiece or piston 66 is positioned on' the shoulder 66, a pin 61 is through the hole 66 of the piston and through the hole 16 in the rod 12 and then through the hole 66 on the other side of the piston. After this pin 61 has been inserted in place, the manually operable 5 knob 16 may be rotated to draw the clamping rod 12 toward the left, as viewed in Fig. 2, which serves to move the pin 61 toward the left and thereby clamp the piston 66 in rigid operating position on the plate 66.

In the grinding of pistons, sueltas those used in'the modern automobile engine, which are'in many cases made of an alumininn alloy casting, the metal expands due to temperature change. The piston expands greater on the diameter colinciding with the axis of the wrist pin and it is, therefore, desirable that at least this portion of the piston be ground to an ovalfor elliptical shape to compensate for the expansion thereof. In'thepiston grinding practice, it is also common 20 practiceto grind the entire surface of the piston to an oval or elliptical shape to compensate for the expansion of the piston due to heating to a runningtemperature so that when the piston becomes expanded due to normal temperature, the piston will fit the cylindrical surface of the cylinder.

In order to obtain the desired elliptical or oval shape on the piston, it is desirable to provide a suitable mechanism for rocing the piston 66 30 toward and from the grinding wheel 26 as the -piston is rotated so as to generate the predetermined shape thereon. Such a mechanism preferably comprises al cam carried by the work supporting spindle 62 whichv engages a follower 35 which is xed to part of the machine structure, such as the table, so that when the spindle is rotatedto rotate the piston in operative relation with the grinding wheel, the-piston will be oscillated during its rotation so that the 40 wheel will produce the desired shape on the periphery of the work piece being ground. In thepreferred form, a camming member is provided which is adjustable so that the extent of oval or elliptical surface may be varied according to the particular requirements. Such a feature is highly important in the use of such an' apparatus in a repair-shop .where automobile motors of various types are being ground so to enable the elliptical shape produced on the piston to be 50 varied as required. As illustrated in the drawing, a iixed follower member 66 is supported on the bar 56. 'I'he follower member 66 is fastened to a bracket 6| by screws 62 and 66 and the bracket'6l l is held in fixed relation on the table llby screws 66 and 66, as shown in Figs. 3 and 4. Asshown in Fig. 3, the follower member is provided with an internal cylindrical surface 65. 'I'he spindle 62 carries a camming-member 66 which is keyed'thereon by a key 61. Thecam- 60 ming member is provided with a cylindrical surface 66 which is arrangedtorldein ent with the cylindrical surface 65.

To maintain the'camming member 66 in operative engagement with'the surface 66 of the fol- 65 lower member 66, a spring 66 is connected at one end .to a stud 66 which is fixed to the follower-member 66. 'Ihe other end of the spring 69 is fastened to a stud 6I which is iixed to the supporting arm 66. lI'he spring 66 is of a suili- 70 cient'tension to maintain the .camming member 66 in operative engagement with .the follower surface during the grinding operation. When the camming member 66. is rotated. as above described, with its cylindrical surface 66 rotat- 75 aclararY to grind the desired relief on opposite sides of the piston, a pair of diametrically opposedadi justable rollers 96 and 91 are mounted onstuds 98 and 99, respectively, on the camming 86. The studs 98 and .99 are arranged melon-1 gated slots and |02 in the camming plate 86.

The studs 98 and 99 may be held in adjusted position relative to the plate 86 by means of the locking nuts |04 and |05. The elongated slots are of a suiiicient length so that the rollers may be adjusted toward the center of the camming plate 86 to a suihcient extent so that the peripheries of therollers 96 and 91 do not project beyond the periphery of the camming disk 86. In such a case, when the spindle 62 is rotated the cylindrical surface.88 of the camming member 86 rides against a portion of the cylindrical surface 85 and causes no rocking motion of the .spindle and, therefore, produces a cylindrical surface on the work piece or piston 66.

If it is desired to grind the piston or a portionthereof to an elliptical or oval shape, the studs- 98 and 99 are adjusted so that the rollers 96 and 91 projectbeyond the periphery of the camming disk 86 by an amount equal to the difference between the radii of the surface it is desired to produce on the piston being ground. That is, the

lrollers 96 and 91 project beyond the disk 86 by an amount equalto Ithe difference between a radius drawn through the long and the short axis of the oval or ellipse to be produced on the piston 66. When the rolls are adjusted to such a position, as indicated in Fig. 3, when the spindle is rotated the rollers 96 and 91 are brought into engagement with the follower surface 85 to rock the spindle 62 toward and from the operative face ofA the grinding wheel. After the camming disk 86 rotates through a partial turn, the camming disk 86 contacts with the'follower surface 85 and the roller 96 moves away from the follower surface 95. During a partial turn, following this relationshipof the parts, the camming disk rides on the fol-.- lower surface to grind a concentric portion on the lpiston until the next roller 91 engages the follower surface 85 and again rocks the spindle toward and .from the periphery 4of the grinding wheel to grind away a portion of the piston on its diametrically opposite sides. By adjusting the positions of the rollers 96 and91 relative to the axis of the supporting spindle 62, the extent of oval or ellipse produced on the finished product. may be varied. In the varrangement shown in Figs. 1 to 3 inclusive, the long axis of ltl'ieoval or ellipse produced remains constant and the short L axis of the ellipse is varied.

supporting bar 50. A sleeve i3 is formed integral with the gear I2 and isprovided with an outwardly extending aiige I|4 which is provided with an aperture I I5. The aperture ||5 is en gaged by a driving pin I I 6 carried by the rotatable driving plate l|1 on the headstock I6.

` A modied form of camming device is illustrated in Fig. 4, in which the bracket 80 vis provided with a xed follower surface |20. A camming member |2l is supported Aon a bushing |22 which is mounted on the spindle 62 and is rkeyed thereto by a key |23. The camming member |2| is arranged so that its periphery may be'adjusted togrind either a true cylindrical surface, an oval or elliptical surface.

In order to adjust the camming ring I 2|, a plurality of opposed adjusting screws |24, |25, |26, and |21 are screw threaded through the ring I2| and bear against the sleeve |22. By slacking olf on the adjusting'screws |24 and |25 and tightening the screws |26 and |21, the ring I2I may be iiexed'to an oval or elliptical shape so that when rotated by the spindle 62 in contact with the xed follower |20, it will cause a rocking movement of the spindle 62 and the work piece 66 to generate a predetermined oval or elliptical shape on the work piece. 1f desired, the

fixed follower member |20 may be replaced with a rotatable'follower roller.

The operation of this apparatus is readily apparent from the foregoing disclosure. 'I'he grinding attachment |8 is inserted in place on a cylindrical grinding machine with the bar 50 supported lon the headstock center 53 and footstock center 54 and the driving pin ||6 engaging the aperture I I5 on the driving flange H4. The camming member 86 is then adjusted to produce a form of the desired shape, that is the camming rollers 96 and 91 the desired amount from the disk 86. In. the modified form, as shown in Fig. 4, the screws- |24, |25, |26, and |21 are adjusted to flex the ring I2I t`o produce a camming surface of the desired 35 shape. A work piece, such as a piston 66,'is then in Fig. 2, to lock the piston securely in operating position. The zheadstock motor is then started to rotate the work through the driving gear II2,

It will thus be seen that there has been provided by this invention apparatus 'in which the various objectshgreinabove set forth together with many thoroughly practical advantages are successfully achieved.A As many possible embodiments may be made of the above inventionand as many changes l might be made in the embodiment above set forth,

it is to be understood that au matter herembefore 60 set forth or shown in the 'accompanying drawing is to be interpreted as illustrative andnot in a A 'limiting sense.

I claim:-

1. A grinding attachment for a grinding ma- 65 chine having arotatable grinding wheel for grind# ing non-circular objects, comprising a vpivotally mounted support, a frame on said support, a rotatable spindle on said frame, a work support on said spindle, means to rotate said spindle, means 70l including a cam to rock said support and frame to rock the work piece towardjand from the grind- 'ingmheL and means to adjust the contour of said cam to vary the extent of rocking of said support.

2. A piston grinding attachment for a cylindrl-75 are adjusted in a diametrical direction to project '45 the gear I and the gear I0 which serve to rotate cal grinding machine hav/ing a rotatable grinding wheel, ahead and footstock center, comprising a support arranged to be supported on said centers, a frame on said support, a rotatable spindle on said frame, a work support on said spindle, means to rotate 'said spindle, means including a cam to rock said support and frame to rock the work piece towardand from the grinding wheel, and means to adjust the contour ot said cam to vary the ex- Y tent of rocking of said support. Y

l3. A grinding machine comprising a rotatable grinding wheel and a rotatable work support which are movable longitudinally and transversely relative to each other, means to traverse the work support and grinding wheel longitudinally relative to each other, means to feed said work support and grinding wheel transversely relative to each other, means to rotate said work support, a pivotally mounted support for said rotatable work support, means including a cam to rock said pivotally mounted support to cause the work to approach and recede from the grinding wheel to grind a non-circular shape on the work, and means to adJust the contour of the cam to vary the extent o1' rocking movement of the work to vary the contour produced thereon.

4. A grinding machine comprising a rotatable grinding wheel and a rotatable work support which are movable longitudinally and transversely relative to each other, means to traverse the work support and grin'ding wheel longitudinally relative to each other, means to feed said work.

support and grinding wheel transversely relative to each other, means to rotate said work support, a pivotal support for said work support, means including a cam to -rock said support to cause the` wheel to approach and recede from the grinding wheel to grind a `non-circular shape on the work, and` means including a plurality of adjustable rollers carried by said cam which may be adjusted towards or' from the cam axis to vary the extent of said camming movement to vary the contour produced on the work piece.

5. A grinding machine comprising a rotatable grinding wheel and arotatable work support which are movable longitudinally and transversely` relative to each other, means to traverse the work,supp0rt`and grinding wheel longitudinally relative to 'each other, means to feed said work support and grinding wheel transversely relative to each other, means to rotate said work support, `a pivotal support i'or said work support,

- means including a cam to rock'said support to cause the wheel to approach and recede from the grinding wheel to grind a non-circular shape on the work, and means including a pair of adjustable diametrically opposite rollers carried by said cam which may be adjusted in a'diametrical directiontovarythe extent otsaidcalmningmonmenttovarytbecontourproduced ontbswork mm). Y/V

iromthegrindin'gwheeltogrindanon-cileular shape .onthe periphery ot the work piece, a plurality of adjusting screws slide transversely, a longitudinally movable table,

means to traverse said table longltudimllyrelative tosaid wheel, aheadamifootstocknaald table, andaplstongrlnding attachment therefor comprisingasupportingmunber'arrangedtobe 4 supportedbysaidheadandfootstochairame pivotally mounted on said Support, a rotatable spindleonsaidframe,aworksupportonsaid spindle, means torrofatesaid slindle, means includingacamtorocksaidsupportnnlitraineau.li astorocktheworkpietowardandi'romthe operativeface oIthegrindIngwMand-means to adjust the'contourof saidcamtofvarythe extentofrockingmovementofthenmportand therebyvarythecontain'producedouthoworkil piece. A

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