US2729924A - Hone - Google Patents

Description

J. B. KLEIN Jan. 10, 1956 HONE 2 Sheets-Sheet 1 Filed Feb. 15, 1954 mnw crv e.

United States Patent HONE James B. Klein, Rockford, 111., assignor to Barnes Drill C0., Rockford,lll., a corporation of Illinois Application February 15, 1954, Serial No. 410,257

3 Claims. c1. 51-1843) This invention relates to honing tools in which elongated stones or sticks of abrasive are guided for radial movement in slots angularly spaced around the tool body, expansion and contraction of the stones being controlled by a conical cam shiftable axially of the tool body. The invention has more particular reference to bones of the above character in which the radial positions of the stones are maintained by friction thus avoiding the use of so-called garter springs for holding the stones.

The general object is to overcome the recognized shortcomings of stone mountings of the above character including inaccuracies in duplicating work bores due to yielding of the stone backing, limitation as to the amount of permissible Wear on the stone, and the danger of shearing oif parts of the stone as it enters the rough bores of successive workpieces.

A more detailed object is to provide for some degree of radial tilting of each stone and backing oif of the leading end as the stone enters the bore of each new workpiece.

Another object is to provide a honing tool having a friction type stone holder and a rigid backing for trans: mitting motion of the expanding cam directly to bottoms of the stones.

The invention also resides in the novel manner of applying the friction holding forces to the stones.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which l j Figure 1 is a fragmentary longitudinal section of a hone embodying the novel features of the present invention. i j

Fig. 2 is a section taken along the line 2--2 of Fig. 1.

Fig. 3 is a perspective view of one of the honing elements.

Fig. 4 is a perspective view of the friction applying device.

Fig. 5 is an enlarged fragmentary view similar to Fig. 1 showing the positions of the parts as the hone enters a new work bore.

Fig. 6 is a fragmentary side view of a modified form of the hone with parts broken away and shown in section.

Fig. 7 is a perspective view of the friction producing device of the hone shown in Fig. 6.

Figs. 8 and 9 are views similar to Figs. 6 and 7 but showing another modification.

In the drawings, the invention is shown incorporated in a honing tool comprising an annular series of honing elements 8 angularly spaced around a hollow rotatable body 10 and mounted thereon for bodilyradial movement into engagement with the wall 9 (Fig. 1) of the work bore to be honed. The body is generally cylindrical and is integral with a tubular end hub 11 coupled through the usual universal joint 12 to the end of a hollow drive l l". Projecting through the spindle is the usual axially shiftable expander rod 14 carrying twoaxially. spaced conical 1 2,729,924 Patented Jan. 10, 1956 cams 15 which are disposed within the body 10 and act on follower projections 16 extending inwardly from opposite ends of expander plates 17. The latter are disposed in radially opening recesses or slots 18 angularly spaced around the body 10 and having parallel side and end walls 19 and 21 between which the plates 17 are received snugly and thus guided accurately for bodily edgewise movement in radial planes. In view of the close fit within the end Walls of the slots, endwise shifting of the plates is prevented and their radial positions closely follow changes in the position of the adjusting rod 14. When the latter is shifted downwardly as viewed in Fig. 1, the cams press the plates 17 outwardly and bodily along the slots 18. After retraction of the rods and cams, the plates may be shifted inwardly.

In the form shown, the individual honing elements 8 each comprise an elongated bar or so-called stick 22 of bonded abrasive and of uniform rectangular cross section throughout its length. Preferably, the side surfaces of the stick are covered over substantially their entire area by thin layers .23 of nonmetallic material which wears down with the Working face 24 of the stick during honing of the bore 9. The layer 23 may comprise a strip, for example of an inch thick, of thermosetting phenolic resin such for example as that sold to the trade as Insurok T640. These strips, which are of the same width and length as the stick inthe present instance, may lie loosely against the sides of the stick or they may, if desired, be bonded to those sides so as to form with the stick a unitary assembly by well known adhesives including ordinary du Pont cement. The combined thickness of each stick and its side pieces 23 is substantially equal to the width of the body slots 18 so that the stone assembly fits closely between the slot walls 19 but is readily slidable edgewise therein.

While opposite ends of each stick 22 may be similarly covered by pieces of sheet plastic, it is preferred to cover the abrasive particles with a thin film 26 as by applying varnish or suitable plastic coating material.

The end surfaces 26 of each honing element are flat and disposed parallel to each other and perpendicular to the hone axis so that the abrasive edge faces 24 presented to the work will remain of equal lengths in all positions of adjustment of the expanding cams and throughout the surface life of the stone. As a result, all parts of a workpiece will be honed to the same degree in a given number of strokes of the hone irrespective of the extent of wear of the stones.

The back surfaces 22 of the stones, which are preferably coated with a thin film of shellac or other plastic material, are adapted for full contact throughout their lengths with the rigid metal backing provided by the outer edge surfaces 17 of the expander plates 17. As shown in Figs. 1 and 2, these plates are of substantial width and very rigid so that, when the follower lugs 16 at opposite ends of the plates are in contact with the expanding cams 15, all ofthe stones are supported radially by a solid unyielding backing. At the same time, the side walls 19 of the body slots provide equally rigid lateral support for the stones throughout the lengths of the latter and to all except the short edge portions beyond the outer periphery of the body 10. With such a mounting, a substantially greater part of the stone may be Worn away in service use before replacement is necessary.

While the cams 15 are retracted during and after withdrawal of the' hone from the finished workpiece, the honing elements 8 are held in their respective slots by friction Which may be exerted on any part of the stone but which is preferably applied to the ends 26 of the stones and in a novel manner such as not to interfere with the desired wide range of expansion of the stones. The endwise forces for deriving the necessary friction are produced by springs 30 acting on gripping devices in the form of projections 31- which bear against one of theflat ends 26 of the stone and urge the latter endwise to hold the other fi a d. against t e o pos t end. w l 21 ct the l t .8.- In h f r h n n h s. 1 h Project .21 3 tqmnt es. t te n f n l of shbt ahti it right angular fi r- 9 Whqse other l s te ral ith? t is iehq r cling h h t the uppe eh q h one. body which y be hd' d l y pen n hhtches. 3 6. o.

; ceive the fingers and locate. the same in longitudinalaline. ment with the stone slots.18. The ring 32 is clamped.

against a shoulder 33 of narrow radial Width the, clampinaforce being a p d. t r h a tat t t e b a 35 threaded onto'the hub, 11. The ring 32 and the fingers 'thereon are composed of resilient material so that by virtue of he e ha e fin r s f e to. fle i l h it h Sh t he es e t Clam in or e, wi l h applied to the stone substantially longitudinally of the l c Th P i of n t h 9 e amp ha h qe is I spaced inwardly from but nevertheless elose to the outer periphery of'the hone body so, as to allow for an optimum. range of outward adjustment of. the stones.

Instead f e. Sh ne fin er 29 b in far ed. n a n as in Fig. 4, they may be mounted individually on, the hone body as shown inFigs. 6 and 7. In this modificaa tion, each finger is integral with oneend of a thin plate 44 disposed in a radially opening slot 45; in the outer end of the home body 10 and clamped against the bottom of'the slot by a screw 46 extending through a longitudinal slot 47 in the bar. The plate is thus adjustable longitudinally of the slot to vary the. bending ofthe radially disposed leg of the finger and therefore the force which the offset projection 31 exerts on' the end of' the stone. in the modified form shown in Figs. 8 and 9, the projections 31 for applying endwise clamping forces to. the stones are located at the lower'or outer end of the hone and formed by the later lly offset ends of plungers 37 slidable endwise in radially opening slots 38 milled in the hone body 10 parallel to the tool axis, The plungers 37 are held in the slots by a cap 39. which. fits over the reduced end of the hone body and is held thereon by suitable means such as a pin 40 received .ina bayonet slot 41 in the cap. The end; of the latter forms abutments for coiled compression springs 42 disposed in the slots 38 and bearing at their other ends against the ends of the plungers 37. The narrow ended fingers 3.1 are. thus urged against the ends'26 of the stones 8 at points close to the outer periphery of the hone body.

During honing of a work bore 9 with a tool of the above character, pressure isapplied continuously on the plunger 14 with the result that the active outer faces 24 of the stones 8 are urged against the bore wall. When the latter has been finished to the desired size, the plunger is retracted thereby releasing the pressure on the stones which, upon withdrawal of the hone from the. work bore,

remain in positions shown in full in Fig, and corresponding to the size of the finished; bore. The diameter of the hone is then somewhat more than that of the rough bore in the next workpiece to be honed. This condition has been a source of considerable difiiculty in prior hones having friction held stones which are frequently broken or sheared off by the edge 50 oftheworkpiece when the ends of the stones come into abutment with the work as V the bone enters-the bore of the next workpiece.

In accordance with one aspect of the present invention, the foregoing difficulty is eliminated through a novel correlation in the size of each honing element 8; and, its mountslightly shorter, preferably about .010 to .020 of an inch than the lengthof the stone slot18, that is, the distance between the opposed end walls 21 of the slot. With the stone urged by its spring 30, in the form shown in Figs. 1 and 5, against the lower end wall 21 of the slot 18, a clearance 52 equal to the difference in the stone and slot lengths and shown on an exaggerated scale in Fig. 5 will be left between the end wall 21 and the opposed flat end 26 of the stone. This clearance, even though it is small, is nevertheless sufiicient, considering the substantial length of the stone, to permit the stone to. tilt in its slot from the normal position shown in full in Fig. 5 to the position shown in phantom. Of course, such tilting may occur only when the cams 15 v are retracted and out'of engagement with the follower lugs 16 as will be the case when the hone is being inserted into the bore of the new workpiece.

The lower or outer end of each stone is tilted inwardly n. h ne oma lly upo e agemen of. h projecting corner 5 1 with the edge of the bore. That is to say h h s on n unt r h d 5 s h hone a to nte he b r f ne rk e n up ar directed but inwardly inclined force is exerted on the corner 51 of the stone. The inwardly'directed component of this force shifts the lower endiof the stone edgewise into the slot 18 as permitted by the clearance 52 which allows the stone to fulcrum on the end of the finger 31 by endwise shifting of the stone against the action of its spring 30 far enough to avoid interference by the lower wall 21.

of the stone slot. The stone in turn exerts a more truly radial force on the expansion plate 17 then in contact therewith and the plate is shifted bodily inwardly amount sufficient to permit the stone corner 51 to slip past the work edge 50 and fully enter the bore 9.

Once the ends of'the stones have been thus shifted inwardly, the edge 50- ofthe work acts as a cam progressively alongthe active faces of the stones so as to tilt the stones reversely until the entire length of each stone has been ing to permit some tilting ofthe stone. in a radial plane 1 and a resultant retraction of the stone into its slot- 18 when the corner 51 (Fig. 5.) of its leading end; encounters the edge 50 atthe end of the borein each succeeding workpiece to be: honed. Usually, this edgel is beveled slightly in prior boringoperations-on the-workpiece. Such I radial tilting is achieved by the making of the overall length of each. stone between the parallel end-' faces 26 pressed inwardly andout of" the way. During such entry of the hone into the bore of the new workpiece, the'plunger 14 remains retracted, the expansion plates 11 being out of contact with the cams'15. By virtue ofthe clearances 52, the stones will shift endwise in their slots 18- when the friction exerted on the active faces 24 during the honing operation issufficient to overcome the force of the springs'30. Such shifting is not however detrimental in view of its short length and because the stones are at the time backedrigidly by the expansionplates. The latter,it'will be noted; are held by the slot walls 21 against endwise shifting so that; the slight endwise shifting of the stones in successive strokes of the hone is not accompaniedby any change in the effective diameter of the hone which is controlled accurately by the posit-ion of the adjusting plunger14; V

When the stones in the hone above described] are new, the. major portions are disposed inwardly beyond the points ofengagement between the fingers 31 and the end surfaces 26 As the stones wear away andare adjusted outwardly, the fingers 31 engage the stone ends at points spaced progressively inwardly toward the inner edges of the stones. Such outward adjustment may continue until about per cent of the stone depth has been worn away, the inner edges of the stones then being disposed close to fingers 31. As a result of this combinedwith the-rigid lateral support provided all the way to the periphery of the hone body, a substantially greater part of the stone is usable than with the stone mountings heretofore used. Moreover, the danger of parts ofthe stones being broken by the initial contact with each new workpiece is ef-. fectually avoided by the provision for tilting. ofeach stone in itsjslo t as described above. I claim as my, invention: I 1 e 1. A bone having, in combination, a hollow rotary od .mean .1 a d qd d hi ss hh a ed Par l el Slots a i t la l spaced. he ear hnd, and ha n Pa al el e d walls, rigid'expansion plates one extending substantially the full length of each slot and fitting snugly between said end walls thereof, a cam reciprocable along the body to engage said plates for shifting the same outwardly in said slots and to permit inward retraction of the plates, elongated abrasive elements each having fiat parallel ends and one guided in each of said slots for bodily edgewise adjustment with the bottom of the element backed by one of said plates, a plurality of gripping devices mounted on said body and engaging the respective elements at points spaced from the active faces of the elements, and resilient means urging said devices against the respective elements and having suiiicient strength to create between each element and the body enough friction to retain the radial position of the element when said cam is retracted, each of said elements being sufficiently shorter than the spacing between said slot end walls to provide enough clearance for tilting of the element in the plane of the slot and into said body as the hone encounters and enters the end of a work bore slightly smaller than the prevailing diameter of the hone.

2. A hone having, in combination, a hollow rotary body, means on said body defining elongated parallel slots angularly spaced therearound and having parallel end walls, expansion plates one extending substantially the full length of each slot and fitting snugly between said end walls thereof, a cam reciprocable along the body to engage said plates for shifting the same outwardly in said slots and to permit inward retraction of the plates, elongated abrasive elements each having parallel side and end surfaces and one guided in each of said slots for bodily edgewise adjustment with the bottom of the element contacting and backed by one of said plates, a plurality of gripping devices mounted on said body and engaging one of said surfaces of the respective elements at points spaced inwardly from the active faces of the elements, and resilient means urging said devices toward the respective element surfaces engaged thereby and each element against the opposite slot wall and having suflicient strength to create between such opposite Wall and the element enough friction to retain the radial position of the element when said cam is retracted.

3. A hone having, in combination, a hollow rotary body, means on said body defining elongated parallel slots angularly spaced therearo-und and having parallel end walls, rigid expansion plates one extending substantially the full length of each slot and fitting snugly between said end walls thereof, a cam reciprocable along the body to engage said plates for shifting the same outwardly in said slots and to permit inward retraction of the plates, elongated abrasive elements each having flat parallel ends and one guided in each of said slots for bodily edgewise adjustment with the bottom of the element backed by the one of said plates in the slot, a plurality of gripping devices mounted on said body and engaging the respective elements at points spaced from the active faces of the elements, and resilient means urging said devices against the respective elements and having sufiicient strength to create between each element and the body enough friction to retain the radial position of the element when said cam is retracted.

References Cited in the file of this patent UNITED STATES PATENTS 1,499,556 Sargent July 1, 1924 1,601,813 Emerson Oct. 5, 1926 2,265,377 Kline Dec. 9, 1941

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