US1640991A - Grinding wheel - Google Patents

Description

1,640,991 1927' B. M. w. HANSON GRINDiNG WHEEL Filed Jan.22. 1925 2 Sheets-Sheet 1 i T F T gvvwzntp'p v enmbme WHEEL Fil ed Jan. 22. 1925 2 Sheets-Sheet 2 Y Patented Aug. 130, 1927. I

A UNITED. sTATEs mom I. w. msox, or muons), commcncur; man un sonv m no: a. WHITNEY, mcu'rons or sun user I. .w. mso s, m czasnn.

enmnnie wmw s application fled The present ap lication is, adivision of my application No. 640,351, filed May 21,1923. I I

This invention relates to the art of grind- 5 ing, and has particular reference to im proved grinding wheels for use in grinding grooved or threaded. members, such as screws, taps or the like, so as to give the j grooves or threads accuracy and precision. The ainrofthe present invention is to provide improved inding wheels by'means of -which threadef 'serrated or grooved memhere may be very quickly ground with extreme accuracy in all particulars so that a superior 'roduct may be more economically produced 1 I In'accordance with the present invention, the grinding wheel is provided with a plurality of concentric cuttingedges or ribs adaptedv to simultaneously grind or operate upon a plurality of grooves'or convolutions, 7

a for instance, the convolutions of a thread or threads. By the use of such a. wheel, the speed at which the grinding operations :are performed isv very greatly increased, and the wear upon the serrations ismaterially decreased so that the time consumed in maintaining the grinding wheel in condition -for accurate grinding is considerably reduced and the likelihood of errors in the work, which would be present if a grinding wheel with a single cutting edge were employed,

due to the rapid wearing down of that edge,-

is substantial y eliminated. Y

3 A further object of the invention is to provide an improved grinding 'wheel,the

serrations of which are soarranged or constructed that a cooling fluid may be passed, during the entire grinding operation, through spaces provided between the grinding Wheel and each of the ribs or the con-' vo'lutions of the thread operated upon, so that the work is prevented from becoming overheated and having its temper drawn by the heat generated during the abrasive action. A further advantage of the arrangement of the serrations on the wheel is that v the heat of the abrasive action on each con- Volution or rib on the work, since each.con-

'volution at any one instance isoperated upon on one side face only,.is relatively less than would be the case if both side faces of the convolution were simultaneously op- Kay 21, 19: sum Io. 040,351. Divided and this January .88, ms.

fat the roots of the grooves application fled Serial Io. 4,107.- 1

erated upon by the serrations. The ment of the serrations on the grind-ingfwheel, n addition to providing spaces through which the fluidmaycpa'ss so-as to maintam the work-relatively cool during operation, is also of advantage in that the serrations may be accurately trued, there be ing ample room between the serrations to accommodate truing mechanism and there being no necessity in shapin the serrations erebetwe'en.

' In accordance with one phase of the invention, the grinding edges orribs onthe grinding wheel are soarrangedand constructed that they. will grind increments from the -conv'olutions of the thread; that is to say,

they will grind the thread down to" its proper form in. stages or steps, each rib or serration performing that portion of the dutyfassign'ed to it. It is possible; by employing a stepped serrated wheel of this sort,

'to accurately true the-thread 6f the work by passing the grinding wheel but once along the work and, since a plurality of grinding edges or ribs are operating simultaneously. the time required to finally grind the thread and take out all of the im rfections and inaccuracies therein, due to h causes, will be materially reduced, so that the tap or screw can be ground at a less cost.

Further'objects of the invention will be in 'part obvious and in part pointed out hereinv after more in detail. 7

The invention will be better understood by the grinding ardening or other reference. to the following description in conjunction with the accompanying drawin s in which similar reference characters re er to similar parts. Figure 1 is a lan view showing one form which the grin ing wheel may take, and a general arrangement or apparatus for supporting the grinding wheel and work upon which it is to operate; v I

Fig. '2' is a diagrammatic view showin another form which the wheel ,may take, an the manner-in which it operates upon a threaded member;

Fig. 3 is a diagrammatic view showing the manner in which the serrations ofthe grinding wheel illustrated in Fig. 1 successively cut small increments from the'thread;'

Fig.4 is a similar view showing the manner in which a thread or. groove is 7 gun when the grinding wheel illustrated in Fig. 2 is employed;

Fi 5 is a view showing the manner in whic a Whitworth thread may be ground; Fi 6 is a diagrammatic view showing the relatlve positioning of a rinding wheel and work for grindin threa s of large lead;

Fig. 7 is an on view of the arrangement shown in Fig. 6, and additionally indicates the bposition of the device for truing the ing wheel; and Fig. 8 is a detail View showing an arrangement which permits of angular adjustment of the grinding wheel.

' The drawings show several forms which my improved grinding wheel may take, it

- being understood that these showings are merely by way of illustration and not to Y be construed in any way "as limitations of the scope of my invention. Quite obviously, my improved grinding devices,.the apparatus and method of truingor shaping the i same, and the method of grinding resulting from the use of my improved grinding devices inay be employed in or used in combination with machines of appropriate con- .struction or desi The machine shown in the accompanying drawings is illustrated more or less diagrammatically for that reason. 1 7

I Referring to-the drawings and, more particularly, to Fig. 1, there is provided in the apparatus a base 10 upon which is slidably mounted the" grinding device, here having the form ofa grinding wheel '11, and a carriage 12 having suitable head and tail stocks 13 and 14:, respectively, for supporting a piece of work indicated at 15. During the operation of grinding, the wheel 11 is ro' tated rapidly buthas no movement in the 'direction of its axis. At the same time, the work 15 is slowly rotated, as by means of a splined shaft 46, and is moved axially, as by means of a lead screw 51 associated with the carriage 12 and connected to the shaft 46 by change gears The relative motions in the work are so proportioned that serrations provided on the periphery of the grinding wheel follow the threads of the work 15 to grind out the 'excess'metal therefrom or'resurface the same, whereby the threads are cut down accurately to their proper size and form. The wheel 11 is mounted on a shaft 17 journalled as at 18 on a slide 19 which may be moved back .and forth in a direction perpendicular to the axis of rotation of the wheel by means of a screw 20 having'a hand wheel 21. if desired, the screw 20 may be provided with a micrometer 22 by means of which very fine accurate adjustment of the positioning of the grinding wheel may be made. A pulley 23 may also be provided on the shaft 17 to rotate the grinding wheel very rapidly.

however, that they may be otherwise-spac its periphery a plurality of serrations or cutting edges. By preference, each of these.

serratlons is in the form of a separate con tinuous concentric ring or rib' to the plane of which the axis of the wheelis perpendicular. One of the generic features of. the present invention resides in so arran ing or shaping these serrations or cutting edges of the grinding devices (whether said edges are stepped or arranged for increment grinding or not) that a cooling fluid, during the grlnding operation, may pass between the grinding wheel and each rib or convolution of the work operated upon so as to minimize the heating effect of the abrasive action on the work and thereby prevent the latter from having its temper drawn. This object may be accomplished by variously arrangin or shaping the serrations, as, for

examp e, by making the grooves 27 in the grinding wheel relatively deeper' than the actual grinding surfaces of the serrations.

wheel may be so arranged that at any given time each of the convolutions of the work is drawings, the serrations of the grinding.

wheels are shown as being spaced apart so that they occur at every other convolution on the thread of the work, it being obvious depending upon the character of the work. By preference, the serrations or cutting edges of the grinding wheel are spaced apart equal to a multiple of the distance between the successive convolutions of the screw op erated upon. When a threadofvery finev pitch is to be ground, it maybe found to be of advantage to space the serrations three jacent convolutions of the thread and the screw. As explained hereinafter more in detail in connection with the description of the truing device, the arrangement of the serrations on the grinding wheel, in addition to providing coolin fluid passages therein, permits ready an accurate truing or four times the distance between the ad-.

operated upon on' one face only;. .for in- 9 i of the grinding faces of the serrations, there 1 being ample room between the serrations to.

insert the diamond points.

In accordance with one phase. of the invention, the grinding wheel is arranged'so that its serrations will successively grind increments from the successive grooves or convolutions of the work. To this end, the grinding device may have serrations or cutting edges of varying or difierent sizes or shapes or both, so that, as the inding wheel is passed longitudinally of ti: work, each cutting ed e or serration will perform but a portion.- 0 the grinding operation, the first cutting edge grinding away a small portionor port-ions. from the sides or (and) root of the thread grooves, as the case may be; the second serration taking off a little more, either from the same part, face or portion or portions of the thread convolutions, and on which a previous serration operated, or on a difierent face or portion thereof, and so on, until the thread groove is of a proper size and shape in cross section. .In the illustrated disclosures of the drawings, the grinding wheel serrations are shown as being of successively increasing diameteror hei ht, and at equal distances from the axis 0 the wheel, as being of suc-' cessively increasing width so that the successive serrations will progressively grind small increments from the sides and roots of the grooves of the threaded members, but it isto be understood that these showings are by way of exemplification only and, ifdesired,

the construction and arrangement may be such that the successive serrations will grind different portions of each thread convolution or groove, as, for example, one serration may grind one face or portion'of the thread groove and the next one will grind the other face or root thereof, and so on. If desired, the serrations may be so arranged that they will progressively grind successive increments from the root of the thread groove or from both the s ides and the bottom or root of the groove or portions thereof.

Referring more specifically to the drawings, in'Fig. 1- the serrations of the grinding I wheel are formed to grind V grooves or threads on the piece of work ortap. ,Thes'e serrations are of progressively increasing size, in the present instance the serrations being all of the same shape and of rogressively increasing diameter so thatt ey will progressively grind small portions from the sides and root of the thread'groove. It will be seen that the serration 29 is. slightly higher, i. e., of greater diameter, than the preceding one 28; the serration 30 is of slightly greater diameter than the'one 29,

and so on until thefinal serration is reached.

(in the present instance the serration '31) which is adapted to. give t e thread groove its final shape and size. It Will be noted that these'serrations are of progressively increasing width at like distances from the axis of the grinding wheel. During the operation of grinding the work, the latter is rotated and is-movedlongitudinally so that the ser-. rations of the grinding wheel follow the groove in the work; The serration 28 will rind a small V shaped increment 28 (reerring to Fi 3); the next serration 29 will grind an ad ltional increment 29'; the serration 30 will grind an increment 30'; and, finally, the .serration 31 will take an increment 31, thereby finishing the thread to exact size. and shape. 1

The grinding wheel shown in Fig. 2 and designated by the character 11" is generally similar to the grinding wheel shown in" Fig.) 1, with the exception that the serrations are truncated. These serrations, designated by the numerals 28, 29, 30' and 31", are of progressively increasing height and, preferably, their truncated edges are of substantially the same width. The serrations are of similar shape and are shown as being spaced apartso as to operate at any one'mo- .vice which may be employed to advantage for shaping the serrations of the grinding ,wheels, reference may be had to the arrange- When this wheel is ein-, v

diagrammatically illustrates the grind a Whitworth'threa'd.

ment shown in Fig. 1 and which is made the subject matter of a separate application. Each of the grinding wheels may be formed from a generally cylindrical integral member of abrasive material or may constitute a structure built up of abrasive disks, as desired. The shaping and truing of the serrations on the wheel may be done by means ofdiarnond points 35, 36 and 37 mounted on a slide 38 which maybe moved back and forth, in parallelism with the axis of the work'spindle, on the base 1.0 by means of a screw 39. having a hand wheel 40 and indexed by a micrometer or scale, as at 41.

The diamond points 35 and 37 may be moved across the respective faces of the serrations, and the diamond point 36 may be advanced'b suitable screws provided with hand whee s or handles 42. The extent to which the diamond points may be moved towards the axis of the-wheel may .be determined by the scales 43. The points 35 and 37 are angularly disposed in accordance' with the .side angles of the thread to be ground, and may be adjustable. By means of the screw'20, the wheel may be brought into position adjacent the diamond points 35, 36 and 37, and thereafter the faces of the serrations are trued to the form and size desired. The diamond point 35 is arranged to cut the right hand side faces of the serrations. (Fig. 1), and the diamond point 37 cuts the face on the left hand side of each serration. The diamond point 36 may be used to rough out the serrations to the approximate depth and to truncate the serrations. To true the serrations of the grinding wheel shown in Fig. 1, the wheel is first moved b the screw 20 into operative elation': to the truing devices; the slide is indexed-to bring one of the diamond points, say the one 35, into proper relation to one, of the serrations, for instance the first one 28; and then the diamond point 35 is moved back and forth along the right hand .face of the serration 28, referring to Fig. 1.

After this face is trued, the slide 38 is in-' dexed so as to bring the diamond point into proper indexed relation to the next serration 29, and the grindingwheel is moved radially, as by turning the hand wheel 21,a very slightdistance' away from the truing device so thatthe serration 29 will be of slightly' ing one. The diamond point 35 will'now be moved backand forth to" true the right hand face of the serration 29., Thediamond point is successively indexed'to'properly operate on the right hand faces of the succeeding serrations, the wheel, each time a new serration is to be trued, being moved a slightly greater distance away from the truing device. After the right hand faces 'of all the serrations have been-true'd, the slide 38 is indexed so as to bring the diamend-point 37 into proper relation to the left hand face -of the serration 28 and after this face istrued, the diamond point is indexed so as to operate-upon the left hand face of the second serration 29, the Wheel being first moved a slight distance away from the truingdevicef The diamond point 37- is then successively indexed so as to op- .erat'e upon theleft hand faces of the re- .maining serrations All of the serrations iqw'ill n'ow be'of V shapeand of increasing diameter. "The side faces of the serrations e mgdfora portion of their depths only '-f ,=beeause ='the grooves in the grinding wheel '1 are 'auhstantially deeper than the extent to which the serrations project intothe' work during the grinding operation.

The-grinding wheel shown in Fig. 2 is truer]. in the same manner as that just degre'ater-diameter than the precedr scribed in connection with the grinding wheel shown in Fig. 1, and, additionally,

the edges of the serrations are truncated so as to form flats. These flats, in the present illustrative disclosure, are all of the same vwidth and are of progressively increasing of serrations or cutting edges aresimultaneously elfectlve, and these serratlons each perform but a relatively small part in grindqng away excess metal from the work to bring the thread to the desired size and shape, the grinding of the work may be very grinding operationof the work, a plurality quickly carried out with precision, and the grinding wheel will notwear out so rapidly as wouldbe the case Where a single cuttin serration were provided, so that repeate truing of the wheel is not required, all of which means that threaded members, perfect in all respects, may be produced in a shorter space of time with less labor and at a materially reduced cost.

that the serrations of the grinding wheel It will be seen that because of the fact grind on only one face of anyone of the 7 thread 'convolutions at any one instant, the

heating effect is considerably lessthan in the case where both sides of a thread are being; cut at the same time, so that the threads on the work will notbe so highly heated that they will. lose their temperhior hardness. The

grooves 27 provide plenty f roomfor a sup-' ply ofcooling fluid to immerse the work while grinding.

Itwill also wide spacing of the serrations of the grinding wheel, and since the grooves in the grinding wheel may be substantially deeper than the extent towhich the serrations project into thework duringthe' grinding operation, there isiaiample room provided to insert the diamon'dpoint to true the wheel and it. is

necessary to true the side faces of the serrations for ,a portion of their depths only, all of which means that a much more precise and accurate form can be thus'more conveniently obtained.

When it is desired to'. grind a thread of large lead angle, such as is' shown in Fig. 6, the axis of the grinding wheel is inclined perpendicularly to the lead angle of thethread on the work. In this position, the

be noted that because of the serrations 55 of the wheel 56 extend substan as would be the case if'the two axes were- 'tially inthedirection of the thread angle of the work 58 instead of across the thread placed parallel. In order to thus angularly adjust the wheel so that its serrations are inclined correspondingly to the lead of the thread, the journal boxes 18 are adjustably mounted, by gibs 60 (Figs. 1 and 8), on an arcuate bracket 61 arising, from the slide 19.

The center of curvature of this bracket is "preferably about a point 62 in the center of the grinding wheel, by which is meant a point at the axis of the wheel substantially midway between itsv ends. The serrations are so shaped and trued that, at the point or line at which they engage the work, they will be of such contour and size as to properly and respectively, operate on those tions or faces of the thread as has planned. Preferably, to true the grinding wheel to cut" the thread to the proper dimensions, the truing device may be placed at the side of the wheel diametrically opposite the grinding point but this will depend on conditions. In the present illustrative disclosure,'the truing devices are moved in the plane including the axis of rotation of the work and the point 62. They move in a practical grindingplane which substantially includes the axis of the work and the line of contact between the work and wheel so that the serrations on the grinding wheel are shaped and trued to desired size and shape. It is true that with the arrangement of Figs. 6, 7 and 8, one end serration will engage the work slightly'above the point of engagement between the central serration and the work, while the other end serration will engage the work slightly below the last mentioned point, but for all practical-purposes this deviation is negligible, and the practical grinding plane may be considered as substantially including theaxis of the work and the point of contact'between the work and the several serrations or at least a mean of those points of contact. 'The apparently widely difi'erent embodiments of this inventioncould be made without depart ,bers comprising a gl vegmaterlal provi .ingfrom the scope thereof, it isintended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and notina-hmiting sense. 7

It is also to be understood that the lanuage used in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might'be said to fall therebetween.

I claim as my invention:

1. A wheel for grinding convoluted members comprising a wheel circular in crosssection and provided with circumferential serrations on its periphery conformin generally in cross section to a screw thread, adjacent ones of said serrations being spaced a distance equal to a multiple of the distance between successive vconvolutions on the work thereby providing channels between the wheel and the work 0 erated upon for the passa e of a cooling uid.

2. grinding device for grinding con! voluted members comprising a grinding- Wheel of abrasive material provided with-a plurality of circumferential serrations varying in size from one another and arranged to simultaneously grind a plurality of convolutions on the work and to successively grindincrements from each of the convolutions.-

-3. A device for grinding convoluted members comprising a grinding wheel generally circular in cross section and provided on its periphery with a plurality of separate parallel serrations having sloping side faces and of substantially the same shape and angle, said serrations being of progressively increasing diameter to cut successive 1ncrements from each convolution on the work.

, 4:. A device for grinding convoluted members comprisin a grinding wheel of abrasive material provi ed with separate parallel sercross sectional shape and angle in a plane tov whlch the axis of the wheel is angularly disposed whereby said serrations in said plane will correspond in shape and angle to the grooves in the work operated upon.

5. A device for grinding convoluted mem- (girinding wheel of abraed with a pluralityof serrations corresponding in cross section to a screw thread, said serrations being of successively increasing choid length in'a plane angularly disposed to the 'axis ofthe wheel rationshaving sloping sides and of the same and said serrations having sloping sides and being of the same'sectional shape and angle insaid glane. p ENGT W HAN SON.

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