US2411851A - Apparatus for and method of smoothing pump bores - Google Patents

Description

M. CASERTA Dec. 3, 1946.

APPARATUS FOR AND METHOD OF SMOOTHING PUMP BORES Filed April 17, 1944' 3 Sheets-Sheet l 7 ||v|r.. 02 9 3 4 b 0O 7 4 7/ a 1] a w 9 a 7%6 b 2 "-www R 1 0 u v Michele Casefla Dec. 3,1946. M. CASERTA 2,411,851

APPARATUS FOR AND METHOD OF SMOOTHING PUMP BORES Fil ed April 17, 1944 Y s Sheets-She et 2 I Michele Caserla- Dec. 3, 1946. M. CASERTA 2,411,851

v APPARATUS FOR AND METHOD OF SMOOTHING PUMP BORES v Filed April 17, 1944 3 Sheets-Sheet 3 M wks I Michele Caseria Patented Dec. 3, i946 s PATENT OFF-ICE APPARATUS FOR AND METHOD OF SMOOTHING PUDIP BORES Michele Caserta, Detroit, Mich., assignor to Thompson Products, Inc., a corporation of Ohio Application April 17, 1944, Serial No. 531,430

' 14 Claims.

-This invention relates to an apparatus for and toa method of smoothing pump and other bores without substantially altering the generated bore shape or contour.

In the construction of rotary vane pumps such as described and claimed in my co-pending application Serial No. 397,763, filed June 12, 1941, the pump bore is so contoured as to make the operationof thepump substantially non-pulsatring.v This is accomplished by forming the bore with a normal cross-sectional contour that comprises a pair of opposite circle arcs having different radii but a common axis of generation, a pairof opposite Archimedes spirals intermediate the circle arcs, and four parabolic spirals joining the ends of the circle arcs to the ends of the Archimedes spirals, all of the curves having a common axis of generation and common tangents at their points of juncture. A bore'of such a contour is rather diflicult to form and to smooth properly, since the tolerances must, be held very close indeed and owing to the non-cylindrical naturerof the bore, special tools andgrinding devices have to be employed.

. Iniaccordance with my present invention, the

boreyof a pump, or Ofa pump liner, is formed in a series of operations... In the case of a pump linen-a solid round billet is first bored to form a cylindrical bore usingsubstantially the maximum lengthof radius that can be employed and yet have the cylinder lie wholly within the desired contour of the finished .bore. Ports are next cut in the sidewall of the liner and the proper contour of the bore 'formedtherein by cam turning or grinding, orby breaching. In this opera tion, the bore is formed accurately to. the desired contour, but, to a thousandth of aninch or so under the final dimensions, just sufficient to permit thedesired amount, of smoothing in the subsequent honing operation.

In the smoothing operation, to which the pres ;ent invention more particularly relates, the

sive material carried externally by a pair of radially extensible blades mounted in an adjustable assembly within a diametral slot in the end of l a, rotatable spindle. The assembly includes means 5 provided by strips of honing stones or other abrafor forcing said blades radially outwardly and for operating said means to adjust the position of said blades until they span a diametral length equal to the diameter of the finished bore. The smoothing operation is efiected by rotating and reciprocating the-spindle carrying the blade relative to the pump liner. In a smoothing operationas carried out by a, device of my invention, the radially extensible blades oscillate as a unit in the diametral slot of the spindle end to follow the contour of the bore as initially formed in much the same way as do the slidable vanes of the rotor in the finished bore of a pump liner during the operation of the pump. Accordingly, it is possible by the use of my invention to smooth a generated pump bore having a constant. diametral dimension through its axis of generation in a very simple and efficient manner, while holding the bore to very close tolerances.

It is therefore an important object of this invention to provide an apparatus for smoothing bores of pumps, pump liners or the like where such bores are of a generated contour having a constant diametral dimension through a common axis of generation. I

It is a further important object of this invention to provide a simple and rapid method of smoothing the internal surfaces of pumps, or pump liner bores, and the like where such surfaces are formed from a plurality of curved surfaces having a common axis of generation and common tangents at their lines of juncture, but are not cylindrical.

Other and further important objects of this inventionwill be apparent from the disclosures in-the specification and the accompanying drawingSi On the drawings:

Figure l is a side elevational view of an apparatus embodying my invention;

'Figure 2 is a fragmentary, front elevational view to illustrate the operation of the clamping mechanism for holding said pump liner in posi tion'during the honing operation;

- Figure 3 is a fragmentary, top plan View of the view of thepump liner'of Figure 5 indicating the axis of generation and the radii of the arcs and curves of which the pump bore is composed;

Figure 7 is a partly diagrammatic view of a point of its reciprocating movement and with the honing strips radially retracted prior to the start of the smoothing operation, with parts in elevation;

Figure 9 is a view similar to Figure 8 but with the honing device at the top of its strip and with the honing strips in operative position, with parts in elevation;

Figure 10 is a top plan view of the honing device;

Figure 11 is a sectional view taken substantially along the line XI-XI of Figure 9; 1

Figure 12 is a sectional view taken substantially along the line XIIXII of Figure 8 with parts in elevation; and

Figure 13 is a sectional view taken substantially along the line XIII-XIII of Figure 9.

The reference numeral Ill (Figure 1) indicates generally a platform or base from which is mounted an upstanding post H for supporting the honing apparatus of my invention. Said apparatus includes a work table I2 adjustably mounted upon said post i! and adapted to be held in adjustedposition thereon by means of a thumb screw 1%.

The work table 12 is provided on its upper face with an annular, recessed holder 53 for receiving the lower end of a pump liner I l. Said holder 13 may be integral with the work table [2 or fixedly attached thereto byany suitable means. The holder i3 is provided with a cylindrical socket I 5 for receiving the lower edgeof said pump liner It with a snug fit. Both the table 12 and'holder 13 are apertured, as indicated by the dotted line I6, to permit the honing device to project upwardly therethrough into the interior of the pump liner l4.

Also supported upon the table 12 is a clamping mechanism, indicated generally by the reference numeral 11. Said clamping mechanism I! (Figure 2) comprises a pair of upstanding plates i8 secured to said work table '5 2 in any suitable manner and having a spacer block 59 positioned therebetween. A rearwardly and upwardly inclined arm 26 is rigidly held at its lower end between said spaced plates H] by means of pins 2| and 22 extending therethrough. At the upper free end of said arm 28 there is pivotally mounted to said arm, by means of a pivot pin 23, a pair of lever arms 21 having bowed-apart end portions 24 and 25. A strip 28 extends between said end portions 25 and 25 inwardly of their extremities. A lever arm 29, having at its upper free end a handle 28, is pivotally mounted at its lower end, as by means of a pivot pin 3!, between said upstanding plat-es i8. Said arm 29 is also pivotally connected near its free end, as at 33;, to a pair of short links 33. The other'ends of said links 30 are pivotally connected as at 32 to the arms 21. The outer free ends 23 and 25 of the lever arms 21 carry members 34 and 35, respectively, that are provided with dependent clamping portions 35 and 31, respectively, adapted to overlie and engage the upper edge of a pump liner l4. Said cross strip 26 is provided with a down-- wardly extending pin 38 for reception in a recess or socket 359. There is one such pin receiving recess or socket 39 in each end of a pump liner l4 (Figure 5).

As shown in Figure 2, when the clamping and holding mechanism is in its operative position, the pin 38 extends into the pin receiving socket 39 and the pump liner engaging portions 36 and 31 are clamped over the upper edge of a pump liner I4. In this position the lever 21 is substantially horizontal and the lever 29 lies forward of the'axis of the pivot pin132, which may be considered to bathe dead center point of the mechanism. Accordingly, in its normal position,

the clamping mechanism can be thrown out of clamping engagement only by a manual pull upon the handle 28 to draw the lever arm 29 back and thus lift the arm 21. The clamping mechanism,

' in its inoperative position, is illustrated in dotted lines in Figure 2.

There is also mounted for adjustment upon the post ll (Figure 1) a driving mechanism, indicated generally by the reference numeral 40, which comprises an arm 4| provided with a bore 42 through which said post I I extends. A thumb screw 43 is provided for locking the arm 61 in adjusted position upon said post. A motor 44 is attached to said arm 4! at one side of the post H. Said motor has a vertical drive shaft near the lower end of which is mounted a pulley 46. Said pulley 46 is adapted to drive, by means of a belt 11, a secondpulleyJlB mounted upon the lower end ofya spindle 49 that extends through a bore 50 in the free end of said arm 4|. A second pulley 5| is mounted upon the extreme lower end of said motor shaft and is adapted to drive a disk 52 mounted upon a pin 53 from the side of the motor housing. Since the pulley 5| and disk 52 are in planes at right, angles to each other, a pair of small pulleys 54 and-55 are used to guide the driving belt 55 that extends around said pulley 5i and disk 52. Said small pulleys 54 and 55 are supported from the motorv housing by means of a branched supporting bracket 51.

The pulley B8 is mounted upon the lower end of the spindle 49 so that said spindle 49'm'ay be rotatedby the motor 44 acting through the drive pulley 46 and the drive belt 41. The hub 58 of said pulley 43 is keyed on said spindle 49 by means of a spline 59 so as to permit reciprocal movement of said spindle. 49 along its vertical axis, while the hub 58 is held against displacement vertically between the horizontal arms of a U-shaped bracket fixedly secured to said arm ll. The horizontal arms of the bracket Bil are apertured, as at 6|, to permit free passage of the spindle 49 therethrough.

A sleeve 62 is mounted upon said spindle 49 nea its upper end between'a pair of fixed collars 63 and 64; Said sleeve 62 is loose upon the spindle Mi but because-"it'is held between the collars 63 and 64 is capable of transmitting axial movement to said spindle t9. .Such axial movement is accomplished through a crank arm 65, one end 66 of which is adjustable in a slot 51 of said disk The other end of said crank arm'65 is connected by means of a pivot pin 68 to one end of a rod 55. The other end of said rod 69 is provided with an eye 10 which engages a shaft 1| journaled in the spaced dependent sidewalls 12 ofsaid table i2. A pinion 13 is fixedly mounted upon said rotatable shaft 1|, so that as the disk 52 is revolved, the crank arm 65,-acting through the rod 53, causes said pinion 13 to revolve first in one and then in the other direction Said pinion13 meshes with a rack 14 formed in the sleeve 62, whereby said sleeve 52, and consequently the spindle 49, is caused to reciprocate vertically 'whenthe motor is running...

upper end of the spindle 49sis.providedwith a diametr'alIslotl5-whichextends clear to the end of said spindle and is partially .closed by anoverlying'clisk .I6he1dthereon by means of screws 'I'Iu (Figure 10) Within said slot I is mounted the smoothing .or honing mechanism, .indicated generally by the reference numeral 11., Said mechanism 1'! comprises'a pa'ir'of members. "I8 and I9, held against'axial displacement between the bottom 86 of said slot I5 and the underside of thecover disk I6 but-bodily movable laterally within said slot I5. Each of said members I8 and '19 is longitudinallygrooved for receiving abrasive strips 8| and 82; respectively. Said strips! and 82 may suitably comprise honing stones and are replaceable when 'worntoo thin.

The members I8 and 19 are provided'along their inner edges with opposed'tapered extensions 83 and 84 (Figure 11) that serv'e' to give said members wider areas of contact with the walls ofthe slot I5 and thus prevent said members from wab-bling or becoming cocked in said slot. Each of said members I8 and I9 is further provided at longitudinally spaced points along their lengths with inwardly directed abutment portions' 85 and 85a, and 86 and 86a for a purpose thatwill later appear; Said members lsan'd I9 are also provided with transverse slots 8'! and 81a (Figures 8 and 9) for a purpose that willpresently be described. I

- Meansare provided for forcing said members I8 and'I9 laterally apart within the slot I5. Such means include an integrally formed member 88 (Figure 12) provided witha "slot lfl9 extending laterally completely therethrough. "Said :member 88 (Figure 8) is formedwith' a wedge-shaped portion 89 at its upper end, liiav'ingupwardly' convergent outer faces 96 and90a, andat its lower end with awedge-shape'd' portion 9! havin'gialso upwardly convergent edges 92 and 92a.-' A rod 93 is provided with a lower threaded portion 94 that is adapted to be engaged in a threaded bore provided forthat purpose in'the upper end of said z'ri embertlig- Said rod 93 carries at its upper free end a'knur'led head 95 to facilitate its manual operation. At itslower end the rod 93 is provided with a portion 96 of reduced diam: eter which is freely received in a soclset formed in'a floating bridge member 9'I.' Said bridge member 91 extends through the slot'-I89 in said member 88 and theends of said bridge'member extend freely into the slots 91' and 81a insaid members wand- 19.- a I 1 With the'honing mechanism 11 in the position shown in Figure 8, that is with-the members I8 and I9 in'their' inwardly retracted state, a pump liner I4 can be slipped over theupper end of said mechanism and clamped in place upon the work table I2. The threaded shaft 93 is then manually turned to move'the honing strip carrying: members I8 and I9 outwardly into the position illustrated in Figure 9. Upon threading said shaft 93'intothe r'nember 88, said member 88 is drawn upwardlyand theaction of the 'tapered surfaces 85 and 85:1,; and 86 and 86a,

working uponthe corresponding abutments 85 and 85a and 86 and 86a causesaid'members I8 and I9 to be spread apart laterally until the surfaces of the honing strips BI and 82 are in working engagement with theinside surface of the pump liner lfll The bridge 91, into which thellower end ofthe shaft 93 extends, prevents longitudinal movement of said shaft 93 when it is being threaded 1 into or out of; the member 88 and'thus causes relative 'a'xialmovement ofthe other, throughout their 'length while being moved radially outwardly during manual operation of the rod-93.5.-.

In =1 )reparing..:appumplinerI4 for the honin operationabout to be described, a solid cylindrical billet may first be provided with an eccentric but truly cylindrical bore. I60 (Figure 7) by means of a;reamer IOI. Said bore I 00 is then re-formed to'the desired contour of the finished pump 'linergasior. instance to the contour indicatedby the dotted line I02. This may be accomplis'hed by broaching. Ports I03 and I04 are cut into the: wall of the pump liner to the size and shape desired, either beforeor after the breaching operations The pump liner I4 is also provided, prior to the honing operation, with the pin receiving recesses 39 (Figure 5) extending inwardly from each of thesend faces on thethicker side ofthe 'pump liner. These recesses 39 also serve an' alinement' purpose in the assembly of the pump-liner in a pump such as. shown in my 00-- pending application Serial No. 397,7 63, filed June 12,1941 I v v:"The bo'rei I92 .atthe start of the honing operation is slightly .undersize' as'compared with the final dimensions of the bore IDZa (Figure 6)'in the finished pump liner. "Thecontourof the bore will, in accordance with known principles, have a common axis of generation, indicated bythe let'- ter A (Figure 6'): which will be concentric with respect to the outer cylindrical surface I05 of said pump'liner. -All' of the diameters of the pump bore1'I82a passingvthrough said common axis of generation A will, of course, be of equal length. In accordancewith one method of obtaining a non-pulsating pump, the contour ofthe bore I 02a isformed by a pair of opposite circle arcspdefined at'their extremitiesby thepoints -I 06 and H11, and bythepoints I88 and,,I09, formed with unequal radiiz-R and r,-respectiv ely, Intermediate the extremities' ofsaid arcs I06--I 81' :and- I08-I 09 are a pair of Archimedes: spirals Lille-III and H2- H3, which are joined to the extremities ofthe circle arcs, by four parabolic spirals, [OB-H2, IUI-IIO,il08- -III, and I09-II3. All of these arcs and 'curveshave, a common axis of generationsA, and they also ,have common tangents at their. points; of junction. All of the diameters passing'through said common axisiof generation A, such asthe diameters I66-.A -Iil8and I0fI- ing of'non eylindrical bores, which are nevertheless formed withia common axis of. generation and'with diameters of constant length.

The operationnot my honing device will now be described:

A pump liner-I4 is inserted over the upper end of the spindle 49 carrying the honing device with thehoning strips 8i and 82 in retracted position, as'illustrat'edin Figure-8; The pump liner I4 fits snuglyin-totheirecess I5 of the holder I3; The

clamping- J mechanism 1 I1 i :then moved into clampingposition-, as illustrated in full lines in 7 Figure 2, the liner [4 having previously been turned until the centering and aligning pin 38 can be inserted into the socket or recess 39. The lever 29 is then thrown over beyond the dead center to clamp the pump liner l4 securely in the holder l3.

Next, the rod 93 is manually turned to draw upwardly the blade spreading mechanism 11 and thus force the honing strips 8| and82 outwardly into firm working engagement with the interior surface of the bore |02a.

The motor 44 is next started up to begin the honing operation. During the operation a cooling fluid, such as kerosene, may be run over the entire honing mechanism. The skirt |2| protects the driving mechanism from the kerosene. The length of the reciprocating stroke of the spindle 49 should previously have been adjusted, by adjustment of the eccentric pin 66 in the slot 61, so that at the extreme positions of the spindle in its stroke, the honing strips 8| and 82 always span the full length of the pump liner |4, that is, at the lowermost position of the spindle, the upper ends of the honing strips 8| and 82 (Figure 8) do not pass below the upper end of the pump liner l4, while at the extreme uppermost point of travel of the spindle 49, the lower ends of said honing strips 8| and 82 still lie below the bottom edge of the pump liner M. This provision is importantif a straight Walled bore, rather than a bell mouth bore, is to be obtained. The amount of the reciprocation of the honing strips 8| and 82 is preferably such as not to bring the ends of said strips within the cut-out wall portions forming the ports I03 and I04, since there would then be a tendency for the ends of the strips, if coming within said cut-out portions, to catch on the.

edges of th port openings and eitherbe damaged or wear away said edges unevenly,

In usual practice, the amount of abrasion of the wall of said bore I02 effected by the'honing operation is of the order of 0.001 inch and is not intended to accomplish other than a, sufficient smoothing operation to make possible a smooth sliding fit between the bore and the vanes of the rotor when the pump is assembled in an operating condition.

As the spindle reciprocates, it is also rotated by the drive including the pulleys 46 and 48 and the driving belt 41. in the neighborhood of 400 R; P. M., but slower or faster rates of revolution can be employed depending upon the type of work being done. As the spindle rotates, the entire blade carrying mechanism H oscillates as a unitlaterally in a series of diametral planes, the honing strips 8| and 82 remaining in fixed spaced relationship relative to each other. The movement of the assembly is similar to that of .the vanes of a rotor in the operation of a vane type pump. During such displacement along their diameters, the members 18 and 79 slide Within the slot with their upper edges confined by the closure J6. and with their lower edges resting against the lower .wall 80 of said slot 15. As previously explained,

the extended contact surface areas provided by the extensions 83 and 84 between said members 18 and I9 and the lateral walls of said slot 15 Y tend to prevent wabbling or cocking of the members within the slot.

During the honing operation, it maybe desirable to adjust the honing strips 8| and .82 outwardly into closer pressure relationship with the surface of the bore undergoing the smoothing operation. This can be accomplished without stop- The rate of rotation is suitably ping the motor 44 by merely grasping the knurled end 95 and giving the rod 93 a twist. With a fair amount of experience, an operator can easily determine to what extent to adjust the diametral span of the abrasive strips 8| and 82, and adjustments are made whenever necessary during the operation of the device without interrupting rotation ofthe spindle. Ordinarily, the honing operation requires avery brief period.

The necessity for the smoothing operation arises from the fact that the bore cannot be perfectly formed in the first instance by broaching or the like. Also, there is usually some distortion due to the heat treatment step that follows broaching.

It is important to note that the method herein described does not control the shape of the bore other than to insure constant diametral length, but is effectiveonly in giving to the bore a smooth finish without substantially altering the generated bore shape, and in making sure that all diameters through'the axis of generation A will have exactly the same length. This insures that the pump vanes will have exactly the same end clearance in all positions of the vanes within the bore.

If desired, the work table I2 can be swung very slightly one way or the other to cause the abrasive strips 8| and 82 to bear more heavily when riding across the ports I03 and I04, thus giving more clearance at those points and closer clearance in the pumping zones between ports, when the liner is assembled and the pump is in operation.

In order to permit the honing strips to be changed without taking the closure disc 16 off and lifting the mechanism 1'! out of the slot 15, the rim of the annular holder l3 (Figure 3) is cut away at opposite sides as at I20, to the lower edge of the liner. The strips 8| and 82 can thus be removed laterally and changed with a minimum of effort. v

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

What I claim is: I

1. Apparatus for honing the internal surface of a hollow article, the bore of which has been formed with joined dissimilar surfaces of generation having a common axis of generation and diameters of constant length, said apparatus comprising a rotatable and reciprocable member having a diametrally extending slot, radially adjustable blades slidably positioned for movement in said slot and having strips of honing material projecting outwardly therefrom, means for adjusting said blades tobring said honing material into working contact with said internal surface and hold said blades after adjustment in rigidly fixed spaced relationship, and means for rotating and reciprocating said member within said bore to effect the honing of said surface to smooth the same without materially altering the curvatures of said surfaces of generation, said blades being freely oscillatable in said slot during said honing operation to permit said honing material to follow the contour of said internal surface.

2. Apparatus for honing the internal surface of a hollow article, the bore of which has been formed with joined dissimilar surfaces of generation having a common axis of generation with all of the diameters of said bore, passing through said axis of constant length, said apparatuscomwardly therefrom, means for adjusting said blades to bring said honing material into working-contact with said internal surface including means for holding said honing-material in adjusted extended'position'with the desired contact pressure against said surface, and means for rotating and reciprocating said member-within said bore to effect the honing of said surface to smooth the same, said'blades and blade adjusting and holding means being freely oscillatable in said slot to permit said honing material to follow the contour of said internalsurface withoutmaterially altering the curvatures of said surfaces of generation;

3. Apparatus for honing the internal surface of a hollow article, the bore of which has been formed with joined dissimilar surfaces of generation having a common axis of generation and constant diametral dimensions, said apparatus comprising an adjustable supporting fixture for holding said article with the bore thereof unobstructed, arotatable and reciprocable member having a diametrally extending slot, an assembly slidably positioned in said slot and having strips of honing material projecting outwardly therefrom, means associated with said assembly for extending said blades to bring said honing material into working contact with said internal surface, and means for rotating and reciprocating said member within said bore to effect the honing of said surface to smooth the same, said assembly being freely oscillatable in said slot to permit said honing material to follow the contour of said internal surface without materially altering the curvatures of said surfaces of generation.

4. In an apparatus of the class described, a member having a diametral sl'ot, radially opposed blades insa dslot carrying outwardly projecting honing surfaces, tapered rigid elements between said blades and in contact therewith for moving said blades into radially extended positions, and an adjusting member cooperating with said tapered elements to effect such radial extens on of said blades and said tapered elements, said blades being oscillatable as a unit in said slot along a diametral plane without change in diametral length.

5. In an apparatus of the class described, a member having a diametral slot, radially opposed blades in said slot carrying outwardly projecting honing surfaces, means associated with said blades for moving said blades into radially extended positions and providing a rigid backing for said blades, and an adjusting member cooperating with said means to effect such radial extension of said blades, said blades and said rigid backing means being oscillatable in said slot along a diametral plane without change in diametral length.

6. In an apparatus of the classdescribed, a member having a diametral slot, radially opposed blades in said slot carrying outwardly projecting honing surfaces, tapered elements between said blades for moving said blades into radially extended positions and providing a rigid backing for said blades, and a manually operable threaded adjusting member cooperating with said tapered elements to effect such radial extension of said blades, said blades and tapered elements being oscillatable as a unit in said slot along a diametral plane without change in diametral length.

'7. In an apparatus of the class described, a.

T cylindrical member having" 'a' slot extending diametrally therethrough,a pair of radially opposed blades mounted in said slot for movement therein along a diametral plane, honing strips carried by said blades and projecting outwardly therefrom, tapered elements for engaging internal faces of said blades, adjusting meansassociated with said tapered'elements for moving said blades radially outwardly uniformly of their lengths, said-adjusting means including an'ex- .tension' projecting beyond an end of said cylindrical' member and manually operable during rotation of said cylindrical member, said honing strips, tapered'elements and adjusting means constituting a unit of rigidly fixed diametral length for any given adjustment and said-unit being movable in said slot, and means forrota'ting said cylindrical member to cause said honing strips to smooth an internal bore with which said strips may be adjusted into contact.

8. In an apparatus of the class descr bed, a rotatable and reciprocable shaft having an open ended slot extending through the axis thereof, a closure member for the end of said slot and an assembly retained by said closure member and freely oscillatable in said slot as a unit of fixed diametral length during operation of said shaft including outwardly projecting parallel strips of abrasive material for the smoothing of internal surfaces.

9. In an apparatus of the class described, a rotatable and reciprocable member having a slot extending through the axis thereof and an assembly freely oscillatable in said slot during operation of said member including outwardly projecting strips of abrasive material for the smoothing of internal surfaces, said assembly also including tapered elements associated with said strips for moving the same into outwardly projecting position and means for actuating said tapered elements during operation of said member.

10. In an apparatus of the class described, a

rotatable and reciprocable member having a slot eration of said member including outwardly projecting strips of abrasive material for the smoothing of internal surfaces, said assembly also including tapered elements associated with said strips for moving the same into outwardly projecting position and means for actuating said tapered elements during operation of said member, said means including a floating bridge and a manually operable member coacting therewith to cause said tapered elements to force said strips outwardly.

11. The method of smoothing an internal non- .cylindrical surface composed of a plurality of dissimilar surfaces of generation having a constantdiametral length through the common axis of generation of said surfaces, said method comprising adjusting a pair only of honing surfaces radially outwardly into working contact with said internal surface, said honing surfaces being maintained in parallelism in all positions to the common axis of generation and being oscillated -without relative movement therebetween in planes passing through said common'axis of generation and rotating and reciprocating said honing surfaces relative to said internal bore surface.

12. The method of smoothing an internal surface the contour of which is composed of a plurality of dissimilar surfaces all having a common axis of generation and the diameters of which passing through said common axis are all of con- 'stan-t length, said method comprising adjusting a pair only of honing surfaces radially outwardly into pressure relationship with said internal surface throughout the length thereof, holding said honing surfaces in relatively fixed spaced parallel relationship to the common axis of generation but freely oscillatable in all diametral planes .passing through said common axis of generation and rotating and reciprocating said honing surfaces relative to said internal surface While maintaining said honing surfaces at all times parallel to each other and in abrading relationship to said internal surface to smooth the same.

13. In an apparatus of the class described, a rotatable and reciprocable shaft having an axially elongated slot extending transversely therethrough, and an assembly confined within the axial length of said slot but freely oscillatable as a unit of fixed diametral length in said slot trans- .versely of said shaftduring operation thereof,

said assembly including a pair of diametrally op- .posed, outwardly projecting, narrow strips of abrasive material for the smoothing of internal surfaces.

14. In an apparatus for finishing a generated bore the cross section of which is characterized by the diameters through its center of generation being all of the same length, a member rotatable about the axis of generation of said bore and axially reciprocal along said axis, said member being provided with a slot in a plane passing through said axis, and an assembly in said slot oscillatable therein as a'unit, said assembly including a pair of opposed parallel abrasive strips to contact the wall of said bore and including means to positively spread said abrasive. strips While keeping the same parallel to said axis.

MICHELE CASERTA.

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