US2277985A - Hydraulically actuated hone - Google Patents

Description

M r 31,19 2, F. J. JESCHKE 1 2,211,985

HYDRAULICALLY ACTUATED HONE Filed Sept. 4. 1937 6 Sheets-Sheet 3 INVENTOR. FRAN K J. JESCHKE ATTORNEY.

March 31, 1942. JESCl-IKE 2,277,985

HYDRAULICALLY ACTUATED HON'E Filed Sept. 4, 1937 6 Sheets-'Sheet4 J 1. 3A. a2

24 g INVENTOR.

FRANK J. JESCHKE BY M ATTORNEY.

F. J. JESCHKE HYDRAULICALLY ACTUATED BONE "March 31,1942.

6 ShaetsShaet 5 F-iled- Sept. 4-, 1937 INVENTOR. FRANK J. JESCHKE Jz'y 3B.

EJ. JE$CHKE I 2,277,985. HYDRAULICALLY ACTUATED BONE 6 Sheets-Shoot 6 INVENTOR.

FRANK J. JESCHKE ATTORNEY.

- Filed Sept. 4-, 1937 m W Q Q Q Q Patented Mar. 31, 1942 UNITED STATES PATENT. OFFICE 2,277,985 HYDRAULICALLY ACTUATED HONE Frank J. Jeschke, Detroit, Mich.,

assignor, by

mesne assignments, to Micromatic Hone Corporation, Michigan Detroit, Mich., a corporation of Application September. 4, 1937, Serial No. 162,566

19 Claims.

This invention relates to apparatus for honing tool is provided with a number of abrasive stonesarranged circumferentially around the body thereof and an actuating mechanism is provided whereby the abrasive stones may be retracted to decrease the diameter of the honing head and vice versa.

It is necessary for the stones to be retracted when the tool is inserted into the bore of a workpiece, and then expanded to engage the cylinder wall. Various types of apparatus have been developed to expand and retract the stones, but all of these have required that the operator adjust each tool individually and have been cumbersome to operate.

It is therefore the principal object of the invention to provide a honing apparatus wherein the tool may be expanded and contracted easily and quickly and with a minimum number of parts.

A further object of the invention is to provide a multiple honing tool in which the various sets of abrasive members may be simultaneously expanded and retracted by a unitary control means.

Another object of the invention is to provide a honing tool which has an easily operated means for adjusting the positions of the abrasive stones and a separate quick acting means for expanding and retracting the abrasive stones.

Another object of the invention is to provide a safety mechanism in a multiple honing apparatus so that damage to the tools, resulting from non-uniform bore diameters, is entirely eliminated..

Another object of the invention is to provide automatic means for distributing the abrading pressure in a multiple honing apparatus in such manner that the bores of smaller diameter will receive a greater pressure than those of a larger diameter.

A further object is to provide a honing apparatus whereby a plurality of bores of slightly difr ferent diameters may be simultaneously honed to a common predetermined diameter in a minimum period of time.

A still further object of the invention is to provide improved fluid pressure means for actuating the stone adjusting member.

Other objects of the invention will be obvious as the description progresses.

It is to be understoodthat the following description is drawn to the preferred embodiments of the invention, and that many changes in form, construction and arrangement may be made by those skilled in the 'art without departing from the scope and spirit of the invention, as set out in the claims appended hereto.

Referring to the drawings, wherein like numerals of reference designate like elements in the following description:

Fig. 1 is a front elevation partly in section of a multiple honing apparatus embodying the present invention.

Figs. 2a and 2b, taken together, constitute an enlarged sectional view of one of the honing tools of Fig- 1. a

Figs. 3a and 3b,- taken together, constitute a partisectional view of a modified type of honing tool adapted to be individually operated.

Fig. 4 is a front elevation, partly in section, of a modification.

The apparatus shown in Fig. 1 is adapted to be used on any of the well-known types of honing machines on the market. Itis particularly well adapted for use on machines of the type shown in the U. S. patent toAlbert M. Johnson No. 1,783,019, issued November 25, 1930, or that shown in the patent to John issued September 5, 1939.-

The apparatus comprises a reciprocating spindle head H), on which is rigidly mounted by means of piston rod II, a pistonlZ. A cylinder 43 surrounds said piston and is capable of reciprocating movement relative thereto. A port M is provided -for admitting fluid into the lower chamber of the cylinder l3. Another port (not shown). is provided in the rear of the cylinder and it communicates thereof.

A thrust plate I5 is rigidly mounted on the cylinder l3 and the central portion thereof forms the lower head of the cylinder. Suitable packing is provided around the piston l2 and rod II to seal the cylinder against leakage of the pressure fluid.

Guide rods l6 and i1 are rigidly mounted with respect to the spindle head l0 and reciprocate E..G. Kline, No. 2,171,799,

with the upper chamber for controlling the flow of pressure fluid into and out of the cylinder l3. It is contemplated that the regular fluid supply of the honing machine on which the apparatus is mounted will be utilized to operate the cylinder l3, but if desired, a separate fluid supply 'may be employed. It is of course necessary to provide a source of pressure fluid when the apparatus herein described is used on a honing machine of the type that is entirely mechanicallyoperated. In any case, the fluid supply may be oil, water, air or some'other suitable medium. It is contemplated, however, that oil will be employed as most of the production type honing machines now in use are oil pressure actuated.

Inasmuch as the thrust plate I5 is reciprocable relatively to the spindle head I8, and the latter .reciprocates (together with the thrust plate and its associated apparatus) during the operation of the machine, it is, of course, necessary to provide flexibl conduits for conducting the pressure fluid into and out of the cylinder l3. Any suitable flexible hose, or its equivalent, may be used.

Reference numerals 24 denote the machine pilot bushings which are rigidly mounted on the frame of the machine by means of a bracket 25. These pilot bushings are for the purpose of guiding the honing tools which will now be described.

Four honing tools are shown in Fig 1, this being the arrangement employed for honing four cylinder motor blocks. honed, a duplicate set of tools is provided for honing all eight cylinders simultaneously. It is of course obvious that six and eight cylinder blocks may be honed simply by providing a longer thrust plate to accommodate the additional honing tools, and V-12 and V-16 blocks are readily honed by providing duplicate sets for simultaneous operation.

Each honing tool comprises an abrading head 26 on which is mounted a set of abrasive stones 21 and a set of non-abrasive wiper guides 28. See Figs, 1, 2a and 2b. 'Both the stones and guides are mounted for radial movement relative to the body of the tool.

The guides 28 (see Fig. 2b) are rigidly mounted on carriers 29. Each of the carriers is pro- I vided with a series of inwardly projecting sloping surfaces which cooperate with complementary surfaces on a slidable cam member 3|. 'Each of the cam members 3| is provided witha hook 32 at its upper end which engages with a groove in the slidable collar 33. A sleeve 34 is mounted for rotation on the body of the tool and has i screw threaded engagement with the collar 33. It is readily apparent that rotation of sleeve 34 will cause axial movement of cam member 3| .thus moving the guides 28 radially of the tool by means of the interaction of cam surfaces 30. Garter springs 35 are provided for retaining the wiper guides on the tool head and for urging them radially inwardly.

Each of the abrasive stones 2'! is mounted rigidly on a metallic backing member 36 which bears on a movable plate member 31. The plate member 31 has a pair of inclined surfaces which bear on the conical surfaces 38-39 of the stone actuating member 4|];

The member 40 has a screw threaded hole in its upper end, the threads of which engage with the threads 4| formed on the lower end 42' of an actuating and adjusting shaft 42. Between the shaft 42 and the lower end 42', a loose pin connection is provided to enable the adjusting Where V-8 blocks are member 46 is provided, as shown in Figs. 1 and- 2b. The upper member 45 cooperates with a female member 41, as shown in Fig. 2a, to provide a,-.universal driving connection between the lower portion of the tool and the driving" adapter 48. The lower member 46 cooperates with a female member 49 formed integrally on the body of the tool head 26. A ball connection 58 is provided at the upper end of the tool head, and at the lower end of the driving adapter 48,

a pin 5| cooperates with a bayonet slot 52 to form a readily detachable universal connection.

The internally screw threaded sleeve 53 locks the members against accidental detachment.

The tool spindles 54 are rotated by the prime mover on the honing machine and the rotation is transmitted to the heads 26 by means of the driving adapters 48, members 45 and 46. The latter two members are interconnected by means of a key 55 (Fig. 212). A screw threaded sleeve 56 is provided to retain the key in place and the set screw 51 may be tightened to prevent accidental rotation of the sleeve.

The gear 43 meshes with idler gears 58 which, in turn, mesh with the internal gear 68 on the adjusting sleeve member 6|. The adjusting sleeve 6| is rotatable on the member 45, but is prevented from moving lengthwise relatively thereto by an annular row of balls 62 which engage companion grooves cut in members 45 and 6| respectively.

63 is a ball ratchet which prevents accidental turning of the adjusting sleeve 6|. It consists of a spring 64 which has a projection 65 hearing on the ball 63. A number of depressions 66 are cut into the body of the member 45, one of which will always be in engagement with the ball 63 thereby restraining relative rotation between members 45 and 6|.

The lower hub of gear 43 is drivingly connected to the shaft 42 by means of a pin 61.

The operation of the abrasive stone adjusting mechanism just described is as follows:

When it is desired to expand or contract the working diameter of the tool, the adjusting sleeve BI is turned by hand in the desired direction. Rotation is thus transmitted to the shaft 42 by means of internal gear 60, idler gears 68 (of which there are four in this instance), gear 43 and pin connection 61.

Shaft 42 rotates the threaded extension 4|, which is integral therewith, and the adjusting member 40 is moved upwardly or downwardly as the case may be.

If the member 40 is moved upwardly, the stones 2! are moved radially outwardly as is obvious from the drawings. It is equally obvious that downward movement of the member 48 will allow the garter springs 59 to move the stone radially inwardly.

It is thus apparent that the stones and wiper guides, respectively, of each tool may be indeendently adjusted to fit bores of diiferent diameters.

The space surrounding each pilot bushing is a reservoir for the coolant fluid which flows into bores through the ports 8|.

In addition to the above described mechanism for expanding and retracting the abrasive stones, 9. separate quick acting mechanism is provided for simultaneously expanding or retracting the stones of all of the tools by power means when it is desired to insert and withdraw the tools from the bores of the workpiece. This mechanism constitutes an important part of the invention and will now be described.

Surrounding each honing tool is a sleeve 68. These sleeves are mounted for rotation with the tools in the thrust plate I 5 by means of ball thrust bearings 69'. Suitable openings are provided in the sleeve 68 so that the operator's fingers may be inserted to manipulate the adjusting and locking sleeves 53 and 6|.

At the bottom of each sleeve 38 is an enlarged collar portion in which is cut a bayonet slot 69 which engages with the coaxial fixed pins 10.

A spring biased plunger 10' is adapted to be moved upwardly to allow the slot 69 to receive the pins 10. See Figs. 2a and 2b. The plunger then drops down under influence of the spring 1! and locks the parts against accidental relative displacement as indicated by the dotted lines.

A spool member H is slidably and rotatably mounted on the shaft 42 and is retained in place by the spring 12 and the, collar 73. Ball thrust bearings 14 and 15 are provided on each side of the spool ll so that rotation of the shaft 42 will not be interfered with.

The operation of the quick expanding and retracting means is as follows:

In Fig. 1, the relationship of the parts is shown as they are when the honing operation is being carried on. The honing tools are at the top of the working stroke. 16 denotes the workpiece. Pressure has been applied to the upper chamber of cylinder I3 and the thrust plate I5 is urged upwardly therewith thereby exerting an upward force on the sleeves 68, spool H, shafts 42 and cone member 40. The nuts l8 have been adjusted so that the plate I5 will contact therewith when the requisite amount of stock has been removed from the workpiece cylinders.

When the honing operation is finished and it is desired to withdraw the tools from the bores, the fiuid pressure is reversed in cylinder l3. This causes the cylinder l3 to be moved downwardly carrying with it plate l5, which in turn,

thrusts spool 'll, shaft 42 and cone member 4|! downwardly, thereby allowing garter springs 59 to retract the stones. The wipers 28 remain in contact with the bore walls so that the tools may be guided out of the bores and into the guide bushings without damage to either. The nuts I9 limit the stroke of the parts in the downward direction.

The honing apparatus is now ready to abrade the bores of another workpiece.

When another workpiece is positioned underneath the machine, the tools are inserted into the bores thereof, and fluid pressure is again imposed on piston I 2 causing cylinder l3, plate l5, sleeve 68, shaft 42 and cone member to move upwardly until the stones engage the bore walls.

It is obvious that by means of the adjusting sleeves 6|, each tool may be individually adjusted to compensate for abrasive wear. This is an essential featureof the machine because the stones in the one or more tools may wear unequally due to higher pressures being applied thereto because of unequal stock removal requirements.

The spring 12, which is duplicated in each the smaller bore.

thus finishing the bore to the predetermined size in the same time required for finishing the larger bores.

An explanation of this function is as follows: Assume that fluid at a pressure of lbs. per square inch is introduced into the upper chamber of cylinder l3 in Fig. 1. Then, if the area of the piston is four square inches, an upward.

thrust of 400 lbs. will be exerted on the thrust plate l5. This thrust will be distributed equally among the four sleeves 68 resulting in an upward thrust of 100 lbs. being exerted on each of the sleeves 68, pins 10 and spools H, provided that the four bores of the workpiece are of exactly the same diameter. If, however, one of the bores should be of slightly smaller diameter than the others, it is obvious that the stones in the smaller bore will contact the bore wall first.

If the preloaded spring 12 was not present, the upward movement of the thrust plate would then stop and the stones in the other three bones of the apparatus would not be moved into contact with their respective bore walls. This would result in the entire thrust of the plate l5 being exerted on the adjusting shaft 42 of the tool in Such an abnormally high pressure (four times normal in this particular case) may cause breakage of the tool or damage to the bore.

To prevent this is the primary function of the preloaded spring 12. In the example being considered, the spring 12 (it being understood that one is present in each tool) is accurately preloaded to a pressure of 100 lbs. Therefore, any pressure up to 100 lbs. on the spool II will not further compress the spring and the adjusting shaft 42 will be moved upwardly the same distance in each of the tools.

However, should the pressure exerted on any one or more of the spools exceed 100 lbs., as would happen if any of the bores were undersize, the spring would be compressed by the excess pressure after contact of the stones with the bore wall until the stones in the other tools contacted their respective bore walls. This action would prevent all of the pressure of the cylinder l3 from being exerted on one tool and causing damage thereto. Under the conditions described, the pressure on the adjusting members of the tool in th smaller bore would be 100 lbs. plus the pressure exerted by the compression of the spring which, of course, would depend upon the amount of compression thereof. The pressure on the adjusting members of the other three tools would be 100 lbs. minus one-third of the excess pressure upon the spring in the smaller bore.

Besides acting as a safety device to prevent breakage, the springs 12 have another very important function. As explained above, the pressure 11 the stone adjusting member in the tool honing the smaller bore will be 100 lbs. plus the'excess pressure on the spring, and the pressure on the stone adjusting members in the tools honing the other bores will be 100 lbs. minus one-third of the excess pressure on the spring in the smaller bore. This greater pressure in the stones in the smaller bore results in the diameter of that bore being enlarged at a faster rate than the diameter of the other bores. Consequently, the bores will be finished to a predetermined uniform size with the same number of honing strokes and without nec essitating any manual adjustment whatsoever of the individual tools. The advantages of this arrangement in high speed production honing is obvious and its importance can not be over-estimated.

Frequently more than one of the workpiece bores may be undersize. Once in a while, a block comes to the honing machines with all bores of a different diameter. The difference in diameter is small, in the order of two thousandths of an inch or less, but enough to cause severe strain on one or more of the tools if some safety device was not provided. With th arrangement described, all of the bores may be finished to a constant diameter automatically without any adjustment of the individual honing tools.

It is, of course, to be understood, that the illustration given above is for the purpose of illustration only. Different conditions will require different pressures, and in arrangements employing six or more honing tools, the difference in the pressures exerted on the stones in bores of different diameters will be correspondingly proportionate. The principle illustrated will apply in all cases however.

Figs. 3a and 3b illustrate a modification of the invention. This form of the invention is intended to be used in honing single cylinder workpieces or' for honing multicylinder workpieces having extreme distances between bore centers.

In Figs. 3a and 3b, the parts corresponding to similar parts in Figs. 2a and 2b bear the same reference numeral. In these figures, the manual adjusting mechanism is identical with that in the multiple honing tools and therefore the description will not be repeated.

The single automatic honing tool differs from the multiple automatic arrangement in that both the fluid pressure actuating cylinder and thrust sleeve are incorporated in the tool. and 3b, I is the cylinder which has heads IOI and 102.. I03 is a piston which is rotatably fixed to the driving adapter 48 by means of a ball thrust bearing I04. Suitable packing I05 and I05 is provided to prevent escape of fluid from the cylinder. 1

A keyway 82 is cut into the upper elongated portion of th piston I03 which cooperates with the key 83 to allow relative sliding movement between the piston I03 and cylinder I00, but prevents relative rotation therebetween.

Ports I07 and I08 communicate with the upper and lower chambers, respectively, of the cylinder. Flexible connections (notshown) are provided for connecting ports I 01 and I08 to a source of fluid pressure supply.

A tension collar I09 cooperates with member I I0 to lock the adjusting sleeve 68 to the lower cylinder head I02 for vertical movement therewith. A look nut III prevents accidental displacement of the collar I09.

The ball bearing II2 allows relative rotational movement between the lower cylinder head I02 and the sleeve 68.

The operation of the device is as follows:

In Figs. 3a and 3b the parts are shown as they are during the honing operation. The cylinder I03 is in its extrem upward position and the stones 2'! are at their limit of expansion.

When it is desired to collapse the stones, fluid 'pressure is introduced into the lower chamber of In Figs. 30/

When the honing is resumed, pressure fluid is introduced into the upper chamber of cylinders I00 which causes an upward movement of the parts relatively to the piston I03 and a corresponding upward thrust on th cone member 40, through the intermediary of shaft 42, spool II, pins I0, sleeve 68 and members I09 and I I0.

Fig. 4 shows the arrangement used when honing six cylinder workpieces. The same arrangement is used for honing straight eight blocks. It has been found that, when honing cylinder blocks with more than four cylinders in line, more sat sfactory operation results when an actuating fluid pressure is provided at each end of the thrust plate.

Inasmuch as the arrangement shown in Fig. 4 is similar to that shown in Fig. 1, a brief description thereof is believed to be sufficient.

The reciprocating driving head of the honing machine is shown at II8. At each end thereof, a piston rod II! is provided. A piston H6 is mounted on the rod and the fluid pressure cylinder H3 is mounted thereon. The thrust plate designated H5, is fixedly mounted on the cylinders as shown. II4 denotes the lower fluid port, I68 the actuating sleeve and I53 the adjusting sleeve. An adjustable cylinder stop nut I00 is provided at each side to limit upward movement of the cylinders and thrust plate. From the description given above, in connection with Fig. 1, the operation will be obvious.

Having thus described the invention, that which is desired to be secured by Letters Patent is set forth in the following claims:

1. In a honing machine, a plurality of honing tools having abrasive stones movably mounted thereon, a reciprocable support for said tools, a thrust plate mounted on said support and capable of movement relative thereto, means on said support formoving said thrust plate relative thereto for expanding and retracting said stones.

2. In a honing machine, a plurality of honing tools having abrasive stones movably mounted thereon, a reciprocable support for said tools, a

thrust plate mounted on said support and capable of movement relative thereto, means on said support for moving said thrust plate relative thereto for expanding and retracting said stones, and adjustable means for limiting the extent of said movement.

3. Apparatus for simultaneously honing a plurality of cylindrical bores comprising a reciprocable support, a thrust plate mounted on said support, means for moving said thrust plate relatively to said support, a plurality of honing tools mounted on said thrust plate for rotating move- 7 said last means whereby said plate is moved relativelyto said tively to said support, a plurality of honing tools operatively associated with said thrust plate for rotating movement relatively thereto, each of said tools being provided with an expansible abrading head and an actuating member therefor, a sleeve connecting each actuating member with said thrust plate whereby movement of said thrust plate relatively to said support efiects an expansion of each of said abrading heads, and means for limiting the expansion of said heads.

In an apparatus for simultaneously honing a plurality of cylindrical bores, in combination, a set of honing tools, means for inserting said tools into said bores, fluid pressure means for simultaneously expanding said tools to engage the walls of said bores, and safety means in each of the tools of the set, said means allowing any tool to expand less than the maximum expansion of any of the other tools of the set while pr0- viding greater pressure thereto.

6. In an apparatus for simultaneously honing a plurality of cylindrical bores, in'combination, a set of honing tools, means for inserting said tools into said bores, fluid pressure means for simultaneously expanding said tools to engage the walls of said bores, and safety means in.

each of the tools of the set, said means allowing any tool to expand less than the maximum expansion of any of the other tools of the set while providing greater pressure thereto, said last means comprising a coil spring.

7. In an apparatus for simultaneously honing a plurality of cylindrical bores of slightly different diameters, a reciprocable support, a thrust plate mounted on said support, a plurality of honing tools carried by said support and opersupport.

10. In a cylinder hone of the type provided with a plurality of expansible abrading members, a honing tool having an expansible abrading head, a driving member for said tool, a piston rotatably mounted in said driving member but fixed against axial movement relative thereto, a cylinder surrounding said piston, said cylinder being capable of axial movement relative to said piston but fixed againstrotation relative thereto, and means joining said cylinder to said tool whereby movement of said cylinder produces the expansion of said head.

11. In a cylinder hone of the type provided with a plurality of expansible abrading members,

a driving member, a piston rotatably mounted in said driving member but fixed against axial atively associated with said thrust plate, eachof said tools being provided with a plurality of abrasive members, means for moving said thrust plate for applying grinding pressure 'to said abrading members, and means for automatically distributing said pressure in such manner that the abrading members in the bores of smaller diameter receive the greater amount of the applied pressure.

8. In an apparatus for simultaneously honing a plurality of cylindrical bores of. slightly diiferent diameters, a reciprocable support, a thrust plate mounted on said support, a plurality of honing tools carried by said support and oper-- atively .associated with said thrust plate and rotatable relatively thereto, each of said tools being provided with a plurality of abrasive members, means for moving said thrustplate for applying grinding pressure to said abrading members, and means for automatically distributing said pressure in such manner that-the abrading members in the bores of'smaller diameter receive the greater amount of the applied pressure,

of said tools.

9. In an apparatus for simultaneously grinding a plurality of cylindrical bores, a reciprocable support, a thrust plate mounted on said support by means of at least one fluid pressure cylinder and piston, a plurality of rotatable grinding tools, each of said tools being provided with a plurality of expansible and retractible abrading members and an actuating member so positioned that axial movement of comprising a coil spring in each said actuating member will expand said abrading members, a sleeve connecting each of said actu-.- ating members with said plate, and means for introducing fluid pressure into said cylinder movement relative thereto, a cylinder surrounding .said piston, said cylinder being capable of axial movement relative to said piston but flxed against rotation relative thereto and means cooperating with said cylinder for expanding said abrading members.

12. In a cylinder hone of the type provided with a plurality of expansible abrading members, a honing tool having an expansible abrading member, a driving member for said tool, a piston rotatably mounted in said driving member but fixed against axial movement relative thereto, a cylinder surrounding said piston, said cylinder beingcapable of axial movement relative to said piston but fixed against rotation relative thereto and means cooperating with said cylinder and tool for expanding said abrading members, said means comprising a sleeve arranged coaxially with said driving member.

13. In a cylinder hone of the type provided with ,a plurality of expansible abrading members, a honing tool having an expansible abrading member, a driving member for said tool, a piston rotatably mounted in said driving member but fixed against axial movement relative theretofa cylinder surrounding said piston, said cylinder being capable of axial movement relative to said piston but fixed against rotation relative thereto and means cooperating with said cylinder and tool for expanding said abrading members, said means comprising a sleeve ar=- ranged coaxially with said driving member and adapted to rotate in unison therewith.

14. In a cylinder grinding tool of the type I provided with an. expansible abrading head in combination, a driving member rotatable with said head, an actuating member for expanding said head, said member being coaxial withsaid tool, an actuating sleeve coaxial with said tool, means connecting said member and sleeve, and

power means in said tool for moving said sleeve axially relative to said driving member.

15. Apparatus for faces, comprising in combination, a reciprocable support, a plurality of grinding tools rotatably mounted on said support, a thrust plate, a thrust sleeve arranged coaxially relative to each of said tools' and rotatably mounted in said thrust plate, a fluid pressure cylinder rigidly mounted in each end of said thrust plate, a piston in said cylinder,

a piston rod rigidly connected to said piston and i to said support whereby said thrust plate and its associated apparatus maybe reciprocated relatively to said support.

16..In a honing apparatus provided with a plurality of honing tools adapted to be simultaneously reciprocated and rotated to abrade the grinding cylindrical ,sur-

bores of a workpiece, a reciprocable support for said tools, means for simultaneously expanding and contracting the abrading heads of said tools comprising a. thrust plate'reciprocably mounted on said'support by means of at least one fluid pressure cylinder and piston.

17. A honing apparatus comprising a reciprocable support, a plurality of honing tools -rotatably mounted in said support, each or said tools being provided with a plurality of expansible and retractible abrasive stones, a thrust plate reciprocably mounted on said support, means connecting said plate to said stones, and means for positively actuating said plate.

18. A honing apparatus comprising a reciprocable support, a plurality of honing tools rofor axial movement toward and from said cylinders, a plurality of spindles rotatably mounted in said gear box, each of said spindles being in axial alignment with one of said cylinders, means disposed in said gear box for simultaneously rotating said spindles, a honing head secured to the outer end of each of said spindles for rotation and reciprocation therewith, an

operating member. mounted within each of said 1 heads, said operating members being movable" axially relative to said head, a cam face on each of said operating members, a plurality of honing stones extending from each of said cam faces toward the adjacent cylinder wall, a shaft extending axially from each of said'operating members, a plate mounted to reciprocate with said gear box, said plate being disposed between said box and said heads, and said plate being permitted a limited axial movement relative to said honing heads, means connecting said plate and said shafts so that movement of said plate in one direction from said honing heads will simultaneously move all of said operating members axially sufficiently to move all of said stones radially a predetermined distance irrespective of the size of said cylinders.

FRANK J. JESCHKE.

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