US2336145A - Method for finishing metal parts - Google Patents

Description

Dec. 7, 1943. G. D. WILD METHOD FOR FINISI'IING METAL PARTS Filed March .30,V 1942 3 Sheets-Sheet 1 Dec. 7, 1943.

G. D. WILD METHOD FOR FINISHING METAL PARTS Filed March 30, 1942 3 Sheets-Sheet 2 Dec. 7, 1943. G. D. WILD METHOD FOR FINISHING METAL PARTS 3 sheet-sheet s Filed March 30, 1942 Patented Dec. 7, 1943 UNITED STATES PATENT OFFICE METHOD FOR FINISHING METAL PARTS Glenn Donald Wild, Cleveland, Ohio, assignor of one-half to Michael Cisar, Cleveland, Ohio 13 Claims.

My invention appertains to the art of finishing metal parts. It deals primarily with the provision of a novel method, and a novel machine for carrying out such method, for effecting a final grinding or finishing treatment of metal parts which have been pre-ground or pre-machined to certain fixed general tolerances.

While my invention as described herein is presented primarily with reference to nal fmishing operations on curved surface metal parts to bring them to the finest tolerances that are required for their use, the invention is equally adapted for use in conjunction with the nishing of metal parts with straight or combined fiat and curved surfaces.

My invention has been evolved as a result of the requirements of today for increasing production of metal parts and has solved certain problems of great diiculty incurred by reason of the methods of finishing and mechanical instrumentalities heretofore available for finishing such parts to the finer tolerances that are being required at this time.

It is well known in the art to which my invention relates that the surface of metal parts produced by pre-grinding operation, bringing the part down to the closest tolerances that can be secured by using the generally known machines for the purpose desired, the actual finished surface referred to, viewed by the naked eye, can be seen to comprise fine feed lines creating projections encircling round metal parts or extending across the surface of fiat metal parts. When the metal parts are further nished, as by the previously described crude processes and as accomplished by my present invention, the said feed lines and all other projections on the surface of the metal, of any nature, are entirely removed to the point of achievement of the final finest tolerances required, and the primary object of my invention has been to devise a method,

land mechanically operated instrumentalities for performing said method whereby to greatly facilitate the bringing of the work to the ultimate required tolerances above referred to.

In the carrying out of my invention, I avail of a method involving novel technique in respect to certain consecutive grinding or finishing actions that are performed upon the work or metal parts, and I utilize especially the novel instrumentality of a resilient grinding wheel with which to obtain a peculiar function in the grinding or finishing process. The said resilient wheel is not only applied to the work by arranging and Workingthe same at special angles, or in peculiar parallel relation to the axis of the work, but the inherent resiliency of the wheel is availed of in order to effect a variable grinding action upon the work in respect to different portions of the grinding surface of the wheel. I have found in practice that the said resilient grinding element as used by me, by being operated so that the greatest pressure is applied to the Work thereby at the lead portion of the element with lessening pressure toward the trailing portion of the element, will grind the work in such a way as to reduce the forming of the so-called feed lines that I have referred to above, during initial operation of the grinding means. Eventually, furthermore, this peculiar variable pressure action of the grinding wheel or element will entirely remove the projection of the feed line and any other projections existing on the surface of the work as the latter is cut away to bring it to the required finest tolerances mentioned before.

Another important phase of my method Yand means of accomplishing the results of my invention lies in the mode of utilizing the choking effect of the ground off particles of metal during the grinding-finishing operation. In other Words, my method involves the use of the regulated or controlled choked condition of the grinding element or wheel to Vary the grinding effect produced thereby, said control being obtained through the employment of variable quantities of tallow or equivalent substance with which the grinding surface of the grinding Wheel is coated or treated, as well as by said manipulative technique as respects the degree of application of pressure of the grinding Wheel to the surface being treated or finished.

In reference to the foregoing so-called control of the choking of the grinding surface of the grinding element by my method, I avail of the phenomenon that the greater the amount of application of tallow to the grinding surface of the Wheel, the less will be the degree of choking effect obtained, and vice versa. In this action, in

other Words, the choking effect may be regulated by reason of the peculiar quality of the tallow or similar material that may be used to lubricate the surface of the grinding element, and to increase or decrease, therefore, proportionate with the amount of the said material used, the ainity between the removed particles of metal ground off of the Work and the surfacelof the grinding element. l 1

A further object of my invention, in reference to the method and means employed as above` outlined, has been to utilize the resilient grinding wheel or element, in performing its grinding function, to obviate any possibility of chattering of the wheel during its application to the work, an objectionable feature of the use of hard grinding wheels. Thus, according to the practice of my invention, an advantageous result ows from the employment of the resilient grinding wheel in that in the use thereof the balance of the wheel may be quickly changed and thus a perfect balanced condition maintained in the wheel. So far as I am advised, the foregoing technique of grinding wheel choking and variable pressure effect has never heretofore been employed in the art of metal grinding, broadly speaking, andirres pective of my specific mode of utilization of these features of my invention as lhereinafter presented.

My method as above generally utilizedis susceptble of being performed by hand under cer-V tain conditions, one such method being the ernployment of the hands of the operator to support and move the work in relation to the grinding wheel with the application of appropriate body o r other pressure to effect the desired results. Also, said method is susceptible of being carried out by the use of different types of machines and will preferably be so performed because greater accuracy, as well as greater production, is possible when machine practice is resorted to. V

In the accompanying drawings I have illustrated one type of machine by which the method of my invention may be co-related manually for accomplishing the method referred to.

In the said drawings:

Figure 1 is a front elevation, somewhat diagrammatic in nature, illustrating the embodiment of my invention in a machine of the engine lathe class wherein many of the lathe parts are utilized after the manner of ordinary lathe operation.

Figure 2 is a vertical section taken approximately on the line 2-2 of Figure l, looking in the direction of the arrows.

Figure 3 is a horizontal section of a portion of the machine, taken about Von the line 3--3 of Figure 1'. Y A l Figure 4 is a top plan View of the central mechanism of the machine to show more fully the mounting of themotor cradle, grinding wheel, shaft, and carriage for the same, upon the superstructure of the machine.

Figures 5, 6, and? are diagrammatic views illustrating the angular disposition Vof the work to the grinding wheel during the first, second, and third operations or treatments of the said work, the views being front elevations.

Figures 8, 9, and are disposed at one side of Figures 5, 6 and 7, respectively, and diagrammatically illustrate the relation of the work to the grinding wheel duringv the three different operations previously referred to as illustrated by Figures 5, 6, and 7, respectively. In Figures 8, 9, and 10 the dotted line position of the work indicates the position ofthe same during one traverse of the work across the face of the grinding wheel, and the work is illustrated in full lines during another traverse thereof across the face of the grinding wheel.

Figure 11 is a greatly exaggerated view 'showing a 'fragmentary portion of the grindingwheel to illustrate its face as acting upon the work, also shown in contact with the facaand the movement of the work Ibeing in the direction of the 'assaut arrow, said view being taken looking down upon the wheel and work.

Figure 12 is a view similar to Figure 11 but viewing the parts in front elevation, the dotted lines showing the approximate formation of the pressure contact area of the work with the face of the wheel.

Figure 13 is a cross sectional view taken about on the line I3--I3 of Figure 11, the work and grinding wheel brokenaway and bringing out more clearly the resilient pressure action between the Work and wheel.

In Figures 11 and 12 the dotted lines at the pressure area between the grinding wheel face and work show approximately the gradually decreasing pressure area from the point of the leading edge to the trailing portion of the face of the wheel.

Figure 14 is a fragmentary View of a grinding wheel having a somewhat different form of grind- Ving face useful for handling of certain types of work. l

v I shall now describe generally the construction of the one embodiment of a machine illustrated in the drawings designed for the practice of the method of my invention.

The engine lathe type machine illustrated in the drawings comprises the bed I supported by the legs 2 and carrying a customary type of headstock 3 and tailstock 4. Upon the bed I is mounted the saddle or carriage 5 slidable to traverse the bed I in the customary manner of lathe construction and operated by a motor 6 supported on the carriage, the manner of movement of the carriage being conventional in the art. In lieu of thecustomary tool rest or support mounted upon the carriage 5, I provide a superstructure frame comprising the four corner posts I connected at the upper ends thereof by crosspieces 8 arranged transversely and longitudinally of the machine. A crosspla-te 9 is connected at its ends and thereby supported upon the longitudinal cross members 8 connecting certain of the posts or standards I of said superstructure frame. The plate 9 forms a support for the outer cradle I0 of inverted U -shape, substantially speaking, which cradle is carried from the plate 9 by the pivotal connection I I, which comprises a screw enabling vthe cradle I0 to be raised and lowered and permitting the pivotal movement of the cradle about said screw las a vertical axis. The cradle IEI is provided with laterally and downwardly extending ,arms I2 at its opposite sides, Awhich arms are pivotally connected at I3 to similar arms I4 carried lby an inner motor cradle I5 shaped generally similar to the cradle Ill and disposed between the sides of the latter. l

The cradleV I5 may be pivotally moved by reason of the pivotal connections I3 aforesaid and may be held in adjusted positions after such movement by means of a set screw IS received by -a threaded opening on a side of the inner cradle I5 zand passing through an arcuate shaped opening or slot I'I on the adjacent side of the outer cradle IIJ. The movement of the inner cradle I5 relatively to the outer cradle I0 may be eiected by a pinion shaft I8 having a handle on its outer end and protruding through an opening in the side of the cradle Ill. The pinion of said shaft is carried at the inner face of the said outer side of the cradle I9 and meshes with an arc-shaped rack I9 fixed to the adjacent outer face of the inner cradle side.V Simple turning movement of the shaft I8 and its pinion designated I8a will effect relative movement of the cradles |10 and l5,

, plate 9. v plate 9 a locking member II a is threadedly en- 'as being carried out by hand methods.

V2,336,1fl5 land their proper relative positions when reached for operation of the machine may be fixed by the set screw I6. The motor 20 carried by the inner cradle I5 is mountedk in any suitable manner therein and `the shaft 2| of said motor has re- `movably attached thereto the grinding wheel 22.

From the foregoing it will be understood that rthe motor 20 is provided with a universal mounting by reason of the provision of the pivots I3 lconnecting the arms of the cradles III and I5 and by reason of the method of pivotally supporting the outer cradle I by the pivot member I I. The pivots I3 connecting the arms I2 and I 4 of the vcradles as described are adapted to be positioned so as to intersect the horizontal plane coincident with vthe upper surface of the work being operated upon. Likewise, the grinding wheel 22 is so disposed, by reason -of its mounting upon Athe shaft 2l, that its face may operate in a vertical plane coincident with the pivotal points I3 of the cradles.

The motor cradle I0 is fixed by any suitable `means to the screw member I I the said screw l member passing through an opening in the cross- Adjacent the upper surface of the crossgaged with the screw member II whereby rota- A suit- I0 from becoming misaligned during operation of `the wheel 22 and to maintain the cradle in the desired adjustment, axially of the screw member II This adjustment may be made during the `movement of the carriage and associated parts yas required by grinding technique to be described The machine above referred to is adapted to carry out the various movements set forth in said process, When certain kinds of work are being finished, by my method.

` In connection with the operating instrumentalities above described in reference to the` superstructure of the machine carried by the carriage 5, there will be employed for supporting the shaft 23 which is the Work being operated upon, the customary centers 24 and 25. The center 24 is carried by the usual shaf-t 26 on the headstock 3 and the center 25 by the usual adjusting screw 27 Von the tailstock 4. The shaft 26 is adapted to be driven by any suitable motor and is equipped with the usual face plate 28 having the lathe dog 29 for coupling to the work to drive the same.

l The motor 20 is capable of rotating the wheel 22 at high speed, and the spindle 26 of the lathe is adapted to be rotated at a considerably slower speed to facilitate the grinding action between 4the shaft 23 and the grinding wheel 22. Under most conditions the shaft 23 is rotated in a direction opposite to the direction of rotation of the wheel 22 to most effectively produce the finish on the surface of the shaft, in accordance with the process.

Y Reference is now made to Figures 11 to 13 of the drawings showing primarily the grinding wheel 22 which, as before stated, is formed of a -resilient body preferably laminated in construction. The face of the wheel 22 is prepared with a grinding surface, and, since different wheels are -employed for certain of the separate operations to be performed by my method, said grinding surface is modified accordingly for such wheels. The contour of the face of the wheel may likewise be 'modified t0 take different forms, one of which l is illustrated in Figure lfi of the drawings, sald .contour depending upon the kind of work to be ywheel structure, it is notable that in the practice of my method there are utilized three method steps of grinding, and the grinding wheel employed for each step is differently prepared on its grinding face because of the nature of the work to be performed by each step of the process.

Describing the grinding wheel as prepared for the first step of my process, it is notable that I utilize for the face of the wheel a relatively coarse #320 emery. The term relatively as above used, is merely employed for purposes of comparison, because the emery is obviously fine-grained. The `said emery is applied to the face of the wheel by the use of a suitable glue or adhesive. In a similar manner the emery wheel or wheels used for the second step of my process are set up with #400 emery and the Wheel or wheels used in the third step of the process are set up with #500 grain emery.

Referring now to Figures 5 to 10 inclusive of the drawings, the method of my invention will be described as it may be performed by hand and in relation to the further preparation of the emery wheels used at each step of the process for carrying out such step.

In Figures 5 and 8 my first process step is depicted diagrammatically, and it is to be understood that the work 23 may be held in the hands of the operator and caused to be pressed against the grinding wheel 22 by manual pressure, including body pressure as may be necessary. As viewed from the front elevation of Figure 5, the work or shaft 23 is disposed ata vertical angle to the face of the Wheel 22 approximately 30 preferably, and said shaft is carried across the face of the Wheel in one direction to enable the latter to perform its grinding operation throughout the area of the surface which is being finished, In the above action the wheel causes the rotation of the work in the hands of the operator who will, by means of his hands, retard the turning ted lines in Figure 8 while the vertical angle remains substantially the same and the work is then carried in the opposite direction. In the above operation, the shaft or work 23 is pressed against the left portion of the peripheral face of the wheel 22 as the Work is carried rightward, and then, when the work is moved on the reverse stroke, it is pressed against the right peripheral portion of the face of the wheel. Now it is understood that the wheel as used in the step just described is that set up with #320 grain emery. According to my process, furthermore, as the Work 23 is carried .across the face portion of the wheel 22, see Figure 11, in the direction of the arrow, the leading edge of the resilient wheel 22 is pressed against with the greatest force and the pressure along the trailing portion of the face gradually diminishes because of the contour of 'the face, the resiliency of the wheel, and the angies at which the work is presented to the face of the wheel.

f The foregoing is also true in relationV tov the movement of the work reversely to that described and in a position reversely to that illustrated in Figure 11 and more clearly shown by the dotted 'line posi-tion ofthe work in Figure 8. In the operation as described in Figures 5, 8, andv l1 above given, it is obvious that the feed lines shown on the work in Figure 11 designated `3l] are substantially perpendicular to the surface of the work or piece 23 as defined thereon by previous action in thepre-grinding operation referred to, and when the work is presented to the face of the grinding wheel 22 as above set forth and permitted to rotateincontact therewith, the said feed lines 30 are'acted upon by the emery on :the face of the wheel 22 in a gradually decreasing amount as the pressure of the face of the wheel on the work decreases. In other words, at the point of contact of the work 23 with the wheel 22 `shown in Figure 11, the same being Vthe leading edge of the wheel, designated a, the amountI of cutting at this point by the emery on the face will be greatest in View of the fact that the greatest pressure is exerted at this point and the wheel affords the greatest resistance at the said point. From the foregoing it will be seen that the pressure diminishes as the surface contact of the sides of the wheel with the Work 23 decreases due to the angularity with which the work is presented to the wheel and to the conformation of the face of the wheel, the said pressure decreasing to a point somewhere lsubstantially beyond the center of the wheel "where it is no longer effective to perform the cutting or grinding operation, thereby becoming zero since the face of the wheel no longer contacts the work piece. This effectively prevents the formation of a trailing line or an additional feed line that would normally prevail if Vfull surface contact of the face of the wheel with the work obtained. In Figure 12 the surface contact of the wheel face is illustrated in dotted lines'ove'r the pressure area on the work or 'piece 23 as 'presented in Figure 11, and from this view it will be fully noted that the pressure area de- "creases to the zero or minimum point at the end for junction of said dotted lines, designated l), and thereafter, since there is no contact of `the face of the wheel with the work as previously set forth, there is no pressure area shown.

In Figure 13, a view taken as previously explained on the line f3-l3 of Figure 11, the ac- -tual contact of the portion of the wheel perform-v ing the grinding operation is sho-wn in vsomewhat exaggerated manner as following the contour of the Work being operated on throughout the lcontact of Ythe face of the wheel therewith, and is seen to be a reverse curve to that of the normal contour of the vwheel periphery, and, Yas is apparent, the periphery assumes that normal contour after it has performed its lcutting yoperation and thereafter retains the proper circumferential relationship until again presented to the work for the cutting operation at the end of a Complete revolution of the wheel. This is vdue to the inherent resiliency of the wheel structure, and this resiliency vhas been availed of by me in an entirely new way for the purposeof grinding metal parts, so far as I am aware.

During the operation of the first step, asabove described, the face of the wheel :is prepared by lapplying tallow (grease stick), or an equivalent material thereto,"very freely, and the quantity ofY tallow vof free application, as above referred to, is maintained throughout the reverse move- 'Imentsof the workh'eld at the proper angles stated. The reason for freely applying the tallo'w as above described is to avoid the choking ofthe wheel face with the metal particles removed by the grinding action of the emery on the face, the tallow, practically speaking, providing a lubricant for retarding or preventing 'the adhesion of the said metal particles to the face and to the interstices between the emery grains. f

I pass now to the second stepv of my process, which is virtually a repetition of the method of presenting and moving the work across the vface 'first operation on the surface of the work. In

this second step of operation of my method the #400 grain emery wheel is employed as previ- 'ously indicated, and of course by the second step any feed lines left on the surface of the work are reduced in number and in size by the grinding yeffect produced. However, 'it is to be understood that in the second step I utilize choking of the wheel for obtaining the ner grinding action that is desired in such step. Therefore, the operator will apply the tallcw sparingly in this second step, as compared with the first step, so as to let the metal particles or nes ground olf the work partially ll into the face of the grinding wheel and the interstices between the grains for effecting the above important -second step of operation.

'Referring now to the third step of the operation of my method, Figures l and l0 of the drawings are illustrative. The work at this period of the method is -supposed know to be clean down to vthe true grain Yof the metal and therefore in this third step VI employ a #500 grain emery wheel face and the same type resilient wheel as stated with reference to the first two steps. Likewise vin this third step the tallow is so sparingly used, much more so than in the second step described, as to completely or valmost completely permit choking of the wheel and this action may be enhanced somewhat `by the employment of a little rosin or rouge. Such treatment of -rthe wheel face by the tallow with Yutmost sparing necessarily r'promotes the affinity between the face and the -metal particles Vground off the work, affording the desired adhesion to substantially fully choke the face in the manner in which this terminology is employed in this specification. According to the -operation-ofthe third step nowdiscussed, it

Vis contemplated that the work shall be carried across the face of the Wheel in a horizontal plane --substantially Yparallel with the plane of the axis movement :in opposite directions, depicted by Figure 1'0.

In the third and `last step of my method as above set forth, the 'vnal tolerance necessary-for the na'l grinding or completion of lthe Work Tis obtained andthe grinding action straightens out the cross-grains on the metal surface of the work and brings the latter to the ultimate finished condition for use, at which time it reaches the true color of the metal.

It is within the purview of my invention, dependent upon the tolerances that are required for the finished metal parts treated according to the practice above described, that I may use the practice of one or a combination of any two of the steps recited, but it is important and essential that the grinding wheel shall be resilient and shall be constructed `and treated substantially in the manner set forth.

Ihave described the iineness of the emery employed for the different grinding wheels of the different steps in the sense of relativity of the sizes of the grains employed and do not wish to be bound to the exact sizes because the grains for each step may be varied somewhat within a desired range of same most suitable for the work to be performed by that particular step.

By the practice of the method above set forth, either manual or by the performance of a machine such as hereinafter described, I have accomplished a tremendous saving of time in the finishing of metal parts of different types or kinds, and I have eliminated a great quantity of wast-age or spoilage that has heretofore been incident to the finishing of such parts to obtain the tolerances referred to herein as susceptible of being achieved, as compared with previously known methods commonly being used today.

Also, the practice of my invention has been adopted andused extensively in the manufacture of metal parts required to be finished to such tolerances as have been secured according to the foregoing description, and which metal parts have been of great consequence and importance to the machines wherein they are used.

Referring to Figures 1 to 4 of the drawings and the machine therein illustrated for the practice of the method of this invention, `it will be very evident that the work or shaft 23 supported in said m-achine is disposed to turn about a predetermined axis and therefore is not susceptible of being shifted as is the work illustrated in Figures 5 to 10 of the drawings when manually supported. The design of my machine aforesaid contemplates that the grinding wheel 22 shall be operated and shall be adjusted for angular dispositions both vertically and horizontally to perform its grinding action upon the work or shaft 23. It is obvious, according tothe showing in Figure 1 that the grinding wheel 22 may be caused to take the positions of relative angularity to the work as depicted by Figures 5, 6, 8 and 9 of the drawings, and is likewise capable of having its face presented to the Work while the axis of the wheel is in a horizontal plane parallel to the axis of the work. The universal mounting of the motor cradle I5 is the means whereby the wheel 22 may be shifted along with the motor shaft to present the face of the wheel at the desired angles according to the method depicted in Figures 5 to 10 and described'above. Of course, in conjunction with said universal mounting, the tilting of the motor shaft 2| by tilting of the cradle I5 within the cradle Ill also permits of the desired adjustments of the grinding wheel 22 necessary for the practice of the method.

Since it is the adopted practice, according to the method of my invention, generally to. check the diameter of the work or the amount of metal ground off the surface of the work periodically,

it is easy for the operator o f the machine to effect the desired angular adjustments of the wheel or the adjustment illustrated in Figure 9 between the work checking operations and at the end of the traverse of the carriage 5 with the superstructure framework in which the motor is mounted.

The manner of effecting horizontal and vertical angular adjustment of the shaft and wheel in the machine described, to carry out the method previously set forth, is readily understood by reference to Figure 1.

During the traverse of the carriage 5 in a left Ward direction, the axis of the wheel 22 is tilted forwardly by means of loosening the set screw I6 and manipulation of the pinion IBa, the contact of the periphery of the wheel being thereby similar to the contact illustrated in Figure 8. This angular relationship was referred to previously as the horizontal angular adjustment, but it is apparent that in the use of the machine to carry out my process, when the wheel is adjusted, and the shaft being finished is supported for rotation on fixed centers, this change is a vertical angular change. Similarly, the vertical angular shifting of the wheel respecting the work now becomes a horizontal angular relationship accomplished by rotating the motor and wheel about the screw member I I as a pivot. The wheel thus assumes the position respecting the shaft, as shown in Figure 5. i

Traverse of the carriage 5 in a rightward direction will necessarily involve shifting of the wheel 22 respecting the shaft as illustrated in Figure 8, the shaft being then in the dotted line position in that figure.

'Ihe procedure with the grinding wheels of steps two and three, illustrated in Figures 6 and 9, and 7 and 10, respectively, will be Vcarried out in the manner previously described, the wheel being shifted and traversing the shaft or work on the machine, as contrasted with movement of the shaft and shifting of the same respecting the wheel, as set forth in the hand method.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l. The method of finishing metal parts, which includes presenting the work to the face of a resilient faced grinding wheel with the work disposed at a vertical angle to the resilient face and likewise disposed at a horizontal angle thereto, effecting a relative bodily movement of the wheel and work while the latter is so disposed and pressed against a leading edge of the face of the wheel, thereupon reversing the relative movement of the wheel and work after reversing the horizontal angle of the work respecting the wheel to maintain the work in pressure .contact with another leading edge of the face of said wheel, and causing movement of the work and wheel at different relative speeds at their contacting portions.` 1

2. The method of finishing metal parts, which includes presenting the work to the face of a resilient faced grinding wheel with the work disposed at a vertical angle to the resilient face and likewise disposed at a horizontal angle thereto, effecting a relative bodily movement of the wheel and work while the latter is so disposed, exerting a contacting pressure of the said wheel face and work such that the pressure is greatest at the leading edge of the face and diminishes toward the trailing portion of the face, thereupon revers` ing the relative movement of the wheel and work after reversing the said horizontal angle of the work, and maintaining the same character of pressure contact of the work and wheel face dur.- ingsuch reversed movement, and causing movement of the work and wheel at different speeds.

3. rhe method of finishing metal parts, which includes pressing the Work against the face of a resilient faced grinding wheel with greatest pressure at the leading edge of such face and gradually4 diminishing away from said leading edge toward the trailing portion ofthe wheel face, causing relative bodily movement of'said wheel and work in one direction, then reversing the direction of relative bodily movement of the work and face while maintaining the same character of diminishing pressure of the wheel and work from the leading edge of the wheel face, and causing different speeds of movement of the wheel and work at their contacting portions during the said opposite bodily movements.

e. The method claimed in claim 3, wherein the work is disposed at a horizontal angle to the wheel face during relative bodily movement in one direction, and ata reversed horizontal angle when the relative bodily movement is performed in the opposite direction.

5. The method of nishing metal parts, which includes applying tallow freely to the face of a resilient grinding wheel to avoid choking, pressing the work against the face of the resilient faced grinding Wheel with greatest pressure at the leading edge Vof such face and gradually diminishing away from said leading edge toward the trailing portion of the wheel face, causing relative bodily movement of said wheel and workY in one direction, then reversing the direction of relative bodily movement of the work and face while maintaining the same character of diminishing pressure ofthe wheel and work from the leading edge ofthe wheel face, and causing different speeds of movement of the wheel and work at their contacting portions during the said opposite bodily movements.

6. The method of finishing metal parts, which includes applying tallow sparingly to the face of a resilient grinding wheel to regulate its action by partial choking, pressing the work against the face of the resilient faced grinding wheel with greatest pressure at the leading edge of such face and gradually diminishing away from said leading i' edge toward the trailing portion of the wheel face, causing relative bodily movement of said wheel and work vin one direction, then reversing the direction of relative bodily movement of the work and face while maintaining the same character of diminishing pressure of the wheel and work from the leading edge of thewheel face, and causing different speeds of movement of the wheel and work at their contacting portions during the said opposite bodily movements.

'7. The method of finishing metal parts, which includes applying tallovir so sparingly to the face of a resilient grinding wheel that the face will be choked by metal particles ground from the work, pressing the work against the face of a resilient faced grinding wheel with greatest pressure atV the .leading edge of such face and gradually diminishing away from said leading edge toward thetrailing portion of the wheel face,l causing relative bodily movement of said wheel and work in one direction, then reversing the direction of relative bodily movement of the work and face while maintaining the same character of diminishing pressure of the wheel and work from the leading vedge of lthe wheel face, and causing different speeds of movement of the wheel and Work at their contacting portions during the said opposite bodily movements.

8. The method of nishing metal parts which includes as a first step of operation, presenting the work to the face of a resilient faced grinding wheel with the work disposed at a vertical angle to the resilient face and likewise disposed at a horizontal angle thereto, effecting a relative bodily movement of the wheel and work while the latter is so disposed and pressed against a leading edge of the face of the Wheel, a second step of operation reversing the relative movement of the wheel and work after reversing the horizontal and vertical angles of the work respecting the wheel to maintain the work in pressure contact with another leading edge of the face of said wheel, and causing movement of the work and, wheel at different relative speeds at their contacting portions during said steps.

9. The method of finishing metal parts which comprises, a rst step of operation of presenting the work to the face of a resilient faced grinding wheel with the work disposed at a vertical angle to the resilient face and likewise disposed at a horizontal angle thereto, eiecting a relative bodily movement of the wheel and work while the latter is so disposed and pressed against a leading edge of the face of the wheel, a second step of reversing the relative movement of the wheel and work after reversing the horizontal and vertical angles of the work respecting the wheel to maintain the work in pressine contact with another leading edge ofthe face of said wheel, and a third step of operation comprising presenting the Work to the face of the wheel with the work disposed in 'a horizontal plane parallel with the axis of the wheel, and at a horizontal angle with respect to said face, effecting a relative bodily movement oi the wheel and work while the latter is so disposed and pressed against a leading edge of the, face of the wheel, thereupon reversing the relative movement of the wheel and Work after reversing the horizontal angle of the work respecting the wheel, to maintain the work in pres sure contact with another leading edge of the face of said wheel, and causing movement of the Work and wheel at diiferent relative speeds at their contacting portions during said steps.

10. The method of finishing metal parts, which includes presenting the work to the face of a resilient faced grinding wheel with the work disposed at a vertical angle to the resilient face and likewise disposed at Ia horizontal angle thereto, applying tallow freely to the face of the wheel, effecting a relative bodily movement of the wheel and work while the latter is so disposed and pressed against a leading edge of the face 0f the wheel, thereupon reversing the relative movement of the wheel and work after reversing the horizontal and vertical angles of the work respecting the wheel to maintain the work in pressure contact with another leading edgerof the face of said Wheel, applying tallow to the face of the wheel in such measure as to effect regulated partial choking of the wheel face, and causing movement of the work and wheel at different relative speeds at their contacting portions.

11. The method of nishing metal parts, which comprises a iirst step of operation including presenting the work to the face of a resilient faced grinding wheel with the work disposed at a vertical angle to the resilient face and likewise disposed at a horizontal angle thereto, applying tallow freely to the face of the wheel and effecting a relative bodily movement of the wheel and work while the latter s so disposed and pressed against a leading edge of the face of the wheel, a second step including reversing the relative movementl of the wheel and work after reversing the horizontal and Vertical angles of the work respecting the wheel to maintain the work in pressure contact with another leading edge of the face of said wheel, and applying tallow to the face of the wheel in such measure as to effect regulated partial choking of the face, and a third step of operation including presenting the Work to the face of the wheel with the work disposed in a horizontal plane parallel with the axis of the wheel, effecting a relative bodily movement of the wheel and work while the latter is so disposed and pressed against a leading edge of the face of the wheel, thereupon reversing the relative movement of the wheel and work after reversing the horizontal angle of the work respecting the Wheel, to maintain the work in pressure contact with another leading edge of the face of said wheel, applying tallow to the wheel face during the third step so sparingly as to permit full choking of said face in its grinding action, and causing movement of the work and wheel at different relative speeds at their contacting portions during all of said steps.

12. The method of nishing metal parts which includes as a rst step of operation, including presenting the Work to the face of a resilient faced grinding wheel with the work disposed at a vertical angle to the resilient face and like- Wise disposed at a horizontal angle thereto, said wheel having a relatively coarse abrasive on the face thereof, effecting a relative bodily movement of the wheel and work while the latter is so disposed and pressed against a leading edge of the face of the wheel, a second step of operation of reversing the relative movement of the wheel and work after reversing the horizon-j tal and vertical angles of the work respecting the Wheel to maintain the work in pressure contact with another leading edge of the face of said wheel, said wheel face having a relatively iiner abrasive thereon than in said rst step, effecting a relative bodily movement of the wheel and work while the latter is so disposed and pressed against a leading edge of the face of the wheel, and causing movement of the Work and Wheel at dilerent relative speeds at their contacting portions during said steps.

13. The method of iinishing metal parts which comprises, a rst step of operation of presenting the Work to the face of a resilient faced grinding wheel with the work disposed at a vertical angle to the resilient face and likewise disposed at a horizontal angle thereto, said wheel having a relatively coarse abrasive on the face Y thereof, effecting a relative bodily movement of the wheel and work while the latter is so disposed and pressed against a leading edge of the face of the wheel, a second step of reversing the relative movement of the wheel and Work after reversing the horizontal and vertical angles of the work respecting the Wheel to maintain the work in pressure contact with another leading edge of the face of said Wheel, said wheel face having a relatively finer abrasive thereon than in said rst step, and a third step of operation comprising presenting the work to the face of the Wheel with the Work disposed in a horizontal plane parallel with the axis of the wheel and at a horizontal angle with respect to said face, said wheel face having a ner abrasive thereon than those used in previous steps of operation, eiecting a relative bodily movement of the wheel and work while the latter is so disposed and pressed against a leading edge of the face of the wheel, thereupon reversing the relative movement of the wheel and work after reversing the horizontal angle of the work respecting the wheel, to maintain the work in pressure contact with another leading edge of the face of said wheel, and causing movement of the work and Wheel at different relative speeds at their contacting portions during said steps.

GLENN DONALD WILD.

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