US2294184A - Honing machine - Google Patents

Description

Aug. 25, 1942.

Filed Feb. 28, 1940 5 sheets-sheet 1 All@ Z5 1942 l A. M. JOHNSON 2,294,184

HONING MACHINE Filed Feb. 28, 1940 5 SheetsfSheet 2 /ber .C70/vwxyz y @fi/., fig, d

#www1-17S Aug. 25, 1942. A. M. JOHNSON 2,294,184

HONING MACHINE Filed Feb. 28, 1940 5 Sheets-Sheet 3 Aug- 25, 1942,

A. M. JOHNSN HONING MACHINE Q son CT T O )lll/11104;

Filed Feb. 28, 1940 5 Sheets-Sheet 5 A. M. JOHNSON HoNING 'MACHINE Filed Feb. 28, 1940 Aug. 25, 1942.

AMM

Patented Aug. 25, 1942 y HONIN G MACHINE Albert M. Johnson, Rockford, Ill., assignor to Barnes Drill Co., Rockford, lll., a corporation Iof Illinois Application February 28, 1940, Serial No. 321,152

Claims.

The invention relates to machines for dressing cylindrical surfaces and more particularly to im provements in honing or lapping machines.

Machines of the above general character are used extensively in dressing cylindrical work where a true and accurate contour and an extremely smooth surface finish is required. The dressing operation consists of relatively rotating and simultaneously relatively reciprocating the work and an expansible and contractible cylindrical abrasive tool or hone. When the relative rotation of the tool and work is continuous, the operation is commonly known as honing and when rotation is intermittent, it is known as lapping. 'I'he term honing as employed hereinafer is intended to embrace both methods of operation.

Honing is essentially an abrading operation and efficient action of the tool is dependent large- 1y upon the pressure with which the abrasive elements thereof are forced against the work. Optimum working pressure is determined by a number of factors of which one of the most important is the character of the surface to be dressech Thus, at the beginning of an operation, while the surface is comparatively rough, it is desirable to press the abrasive stones against the work with relatively light pressure to avoid subjecting the elements to excessive strains. As the surface irregularities are reduced, the pressure may be increased without danger of harmf ing the abrasive elements and in fact should be increased substantially to maintain the operating emciency'of the tool at a maximum.

Various mechanisms have been proposed heretofore for eifecting an intermittent positive expansion of the tool in timed relation to its reciprocation. In practice, however, these mechanisms have been unsatisfactory due largely to the extreme difficulty of properly coordinating the tool expansion with the rate at which the metal is removed from the work. Thus, if the tool is expandedl more rapidly than the surface of the work is reduced, the abrasive stones are subjected to excessive pressure as well as destructive strains which materially reduce the useful life of the elements and seriously affect the nnish produced on the work. On the other hand, if the rate of tool expansion is too slow, the

eiiiciency of the machine is greatly reduced with.

a resultant increase in production costs.

The present invention aims to overcome the difliculties heretofore encountered by providing improved tool expanding mechanism operative on the work at a rate readily adjustable to enable the tool to operate with maximum emciency throughout the honing cycle.

Another object is to provide novel means for supplying accurately regulated impulses of pressure fluid. to a pressure fluid operated tool exndingmechanism of a'honing machine of the Still another object is to provide improved means for expanding a plurality of honing tools simultaneously.

Other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiments illus` trated in the accompanying drawings in which:

Figure 1 is a perspective view of a honing machine embodying the features of the invention.

view of the reciprocatory head of the machine showing details of the spindle driving and tool expanding mechanisms.

Fig. 3 isfal transverse vertical sectionalview:

of the head shown in Fig. 2.

Fig. 4 is a side elevational view of the booster pump and associated apparatus for supplying impulses of pressure fluid to the tool expanding means, the pump being shown in section.

Fig. 5 is an end elevational view of the booster pump mechanism shown in Fig. 4. v

Fig. 6 is a vertical sectional view of a modified form of tool expanding mechanism.

Fig. 7 is a partially sectioned top view of the,

vertical multiple spindle honing. machine of thetype in which the tools are rotated and reciprocated relative to 'stationarily supported.' Jwork pieces, it is to be understood that it may be incorporated in other types of honing and lapping machines. `It is also to be understood that various changes and modifications may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention as expressed in the appended claims.

Fig. 2 is a fragmentary horizontal sectional@` Referring now to Fig. 1 of the drawings, the machine selected to illustrate the invention comprises generally a rigid .base II from which rises an upright frame or'column I2. Spaced parallel guide bars I3 rigidly mounted on the face of the frame constitute a guideway for a. reciprocatory head I4 which, in this instance, is equipped ywith a plurality of vertically disposed spindles I5 each adapted to carry on its lower end a honing tool I6. Such tools are well known in the art and include a series of abrasive elements or stones I'I arranged around the periphery of a cylindrical carrier for movement radially thereof. The stones are normally held in their inner or contracted position by means of annular springs I8 and are shifted outwardly or expanded by means of an adjusting rod I9 (Fig. 3) extending axially through the hollow shank 20 of the tool.

A work piece 2| to be operated on by the tools, is held in a suitable fixture 22 mounted on the front portion of. the basel II which thusl constitues the work support of the machine. The

particular `work piece illustrated comprises a conventional motor block having a plurality of parallel cylinders the surfaces vof which are to be dressed. It will be understood, of course,l

that externa1 surfaces may be dressed in a similar operation by using an appropriate form of honing tool.

, As indicated above, relative reciprocation of the tool and work is effected in the exemplary machine by reciprocating the tool support or head I4; The head reciprocating; means as herein shown, is yof the well known pressure uid operated type including a vertically disposed cylinder 26 (Figs. 1 and 8) havinga working piston 2l operatively connected with the head by a pist0n rod 28. Pressure fluid is supplied to the cylinder by a pump P preferably of the high volurne, high pressure type through a hydraulic circuit in which is interposed a reversing valve V of suitable and well known construction. A low pressure pump Ps supplies pressure uid for opf erating the valve V and other auxiliaries as will appear presently.

As herein shown, the supply of pressure fluid and 3l and an intermediatestop 32 arranged to' cooperate with an operating lever 33 operatively connected with the movable member of the pilot a helical gear .4I meshing with an elongated helical pinion 42 extending longitudinally of the head and journaled in suitable bearings 43 carried on the end walls of the head.- The pinion 42 is arranged to be driven in vwell known man-l ner by the motor M (Figs. 1 and 8) through the medium of a solenoid actuated clutch C (Fig. 8), a splined drive shaft 44 (Figs. v1 and 3) and a suitable gear 'train 45 (Fig. 3) enclosed in the head. As will be seen by reference to Fig. 3, the pinion 42 is disposed at one side of )the head. thus leaving the inner ends of the spindles unobstructed for installation of the tool expanding mechanism.

The spindles I5 as herein shown, are constructed with a particular view o f accommodating power expanded honing tools of the type hereinbefore referred to. To this end the spindles are of tubular form as shown in Fig. 3. Extendator herein shown as a cylindrical rod 5I having` its lower end abutting against the tool adjusting rod i9 and anchored at its upper end in a tubular plunger 52 sldably fitting into the upper end of the spindle. The rod is guided adjacent its lower end in a bushing 53set in a counterbore within the spindle. A coiled `compression spring54 interposed between the bushing and the lower end of the plunger 52 yieldably urges the rod and plunger upwardly or away from the tool actuating rod I9. With the actuatorin its upper position the tool is permitted to contract under the inuence of the springs I8.

Suitable power actuated means is provided for` shiftingall of the actuators simultaneously to expand the associated tools. In the preferred `form shown in Figs. 2 and/3, the tool expanding tween the side walls of the head, the-number of valve. The' stops 30 and 32 define the limits of the working stroke of the vhead while the stop 3i denes the upper limit of the withdrawal stroke in which the tool is withdrawn from ther fect the relative rotation of the tool and work required in the honing operation. Keyed to the upper end of each spindle. i5 is such webs depending upon the over-al1 length of the head.

To provide an operative connection between the shaft-and the actuators, the shaft is provided with an eccentric cam element 58 extending over leach spindle. Cooperating with the cam is a. pin 59 having a head 6i) interposed in the path of the cam, the shank of the pin being rotatably supported in a bushing @I set in the upper end of the plunger 52. An antifriction bearing t2 interposed between the upper end of the plunger and the head of the pin takes up the thrust of the cam and permits the pin to remain stationary while the plunger rotates with the spindle.l This eliminates unnecessary wear on the heads 6B and cam element 58.

The cam element 58 is so formed that when the shaft is in the normal position shown in Fig. 3, each plunger occupies its uppermost position wherein the abrasive elements of the tool are contracted. When the shaft is rocked out of normal position, the cam element engages the heads 5D and forces the plungers 52 downwardly, thus expanding the tools. Upon return of the shaft to its normal position, the springs 54 return the plungers to their normal position to contract the tools.

1n the modified form shown in Fig. 6, the 0perative connection between the shaft 55 and the various tool actuators is provided by a series of pinions 63 fixed to the shaft in line with each spindle. The actuator rods (corresponding to the rods 5I hereinbefore described) are, in this instance, extendedbeyond the upper ends of the spindles and each is provided on its projecting end with a rack 64 meshing with the associated pinion 63. 'I'he rod 5I is suitably guided for axial movement and the spindle is rotatable relative to the rod. No restoring spring (such as spring 54) is required for the actuator rod as the movements of the shaft 55 in either direction are transmitted positively by the rack and pinion connections.

Any suitable means may be employed for rocking the tool actuating shaft 55 for expanding and contracting the tools. It is preferred, however, to utilize pressure fluid operated means for this purpose because oi' its compactness, reliability of operation and ease of adjustment. A preferred form of pressure fluid operated means is shown in Figs. 1 and 2 as comprising a cylinder 65 having a working piston 51, provided with a piston rod 68 terminating at its outer end in a rack 69 meshing with a pinion 'l0 fast on the outer end. of the actuator shaft 55. In the particular form illustrated, the rack is guided in a slideway 1| defined by the side walls of a generally rectangularcasing 12l rigidly secured to one end of the headv I4.

The arrangement of the cylinder and pist`on mechanism is such that the shaft 55 is in the normal position shown in Fig. 2 when the piston 61 is at `the outer end of the cylinder. In this position of the sh'aft, the actuators are withdrawn and the tools are contracted. Upon introduction of pressure fluid into the outer end of the cylinder, the piston 61 is moved forwardly, thus rocking the shaft about its axis and causing the cam 58 to shift/the actuators and thus expand the tools. The extent of this movement is determined by an adjustable stop herein sh'own as a screw 13 threaded into the end wall of the casing 12 and having its inner end disposed in the path of the rack 69. Thus, by simply turning the stop screw, the limit position of the rack and the associated tool actuating instrumentalities can be regulated with a high degree of accuracy.

In some instances, as where a plurality of tools of large diameter are employed, it may be desirable to provide two or more pressure fluid operated mechanisms for effecting tool expansion. In .such cases, the shaft 55 is conveniently con-- structed in separate sections, each' provided with cylinder and piston actuating mechanism such as that above described.

Pressure fluid may be supplied to the cylinders 66 in any suitable manner. The present invention, however, provides novel pressure fluid circuits andapparatus for this. purpose whereby expansion of the tools in to relatively light engagement with the work is effected quickly and thereafter as the honing cycle proceeds,rthe tools are expanded in incremental steps under control of suitable power actuated timing means. The arrangement'is preferably 'suchI that the pressure exerted by the tools on the work is'increased pr'ogressively as required for maximum operating efficiency.

Pressure fluid for eecting the initial expansionk of the tools may be conveniently derived from the pump Pa which supplies pressure fluid for Operating the valve V. As above explained, the pump ordinarily usedfor this purpose is of theV type adapted to supply a small volume of fluid at relatively low pressure. The pump as shown in Fig. 8, draws fluid from a sump or reservoir R and dissure -of this fluid being controlled by an adjust- Sump.

able relief valve V2 which' opens automatically when the pressure exceeds a predetermined value and returns excess fluid to the sump by way of a drain duct 11.

In order to insure an adequate supply of pressure fluid to effect quick expansion of the tools. a substantial amount of fluid under pressure is stored in an accumulator A (Fig. 8) oi' suitable and well known construction to' which the pressure duct 18 is connected. The now offpressure fluid from the accumulator to the cylinder 55 is controlled in. this instance by a direction control valve V-l having a plunger 80 yieldably held in a retracted position by a coiled compression spring 8l and adapted to be shifted to an operated position by a solenoid SOL. The plunger 80 when in normal retracted position, directs pressure fluid from the accumulator to the inner end of the cylinder 58 through a duct including a pipe I2, a header 82 (Fig. l) and a exible tube 82a. The fluid shifts the piston 61- toward the outer end of the cylinder thereby turning the shaft 5,5 in a direction to contract the tools. At the same time the outer end of the cylinder is connected with the drain 11 so that the spent pressure fluid fromI the outer end voi' the cylinder may be returned to the 'I'his connection includes a flexible tube 93, the header 82f and a pipe'83. between the header andthe valve.

To expand the tools, the valve plunger is shifted to its operated position in which it directs the pressure fluid from the accumulator to the outer end of the cylinder 66 and connects the inner end of the cylinder to the drain duct 11 for returning spent pressure fluid to the sump. The pressure fluid circuit as shown in Fig. 8 includes a chamber 84 communicating with a booster pump P-l which gradually increases the pressure of the fluid in the cylinder and therefore the pressure exerted by the tools on the work following the initial expansion of the tools by the pressure fluid supplied from the accumulator. To this end, one

duct 85 extends from the valve V-3 to the chamber while another duct 86 extends to the chamberv `h'erein shown as valves of the spring pressed ball type, are installed at the incoming and outgoing ports of the chamber 94 to prevent reverse flow of pressure fluid when the booster pump is operating I as will be explained presently.

While the booster pump P-I may be of any suitable type, it is preferred to employ a pulsatoi pump of the cylinder and piston type capable of delivering impulses of fluid at a pressure substantially'higher than the pressure of the fluid supplied from the accumulator. The preferred form of pump shown in Figs. 4 and 5 comprises a casing 9i in the form of a metal block having a transverse bore closed at one end as byr a plug 92 to form the chamber 84 previously referred to. As herein shown, the casing is removably secured by screws 93 to one end of al bracket 94 which, in turn, is secured to the side of the machine frame I2 as shown in Fig. 1.

The pump cylinder as herein shown comprises lower end into the chamber 84. Slidable within charges it under pressure to a duct 1l, the presthe cylinder is a plunger 96 having its outer end projecting above the casing and terminating in an enlarged head 91. A coiled# compression spring 98 interposed between the head 91 and the upper end of the casing urges the plunger vwardly, the fluid-is through the duct er 92 to supply a succession block 8i.

its lower end through a passage |09 with the ered at each impulse and yand thus determines outwardly so that pressure fluid supplied from the accumulator may ilow intoA the lower end of the cylinder. When the plunger is moved downforced out of the cylinder and through the check valve V- to the tool expanding cylinder 66. Reverse flow of fluid 85 is prevented by the check valve V-8.

Means is provided for reciprocating the' plungof pressure fluid impulses to the tool expanding cylinder as the honing operation proceeds. The plunger reciprocating means as shown in Figs. 4 and 5 comprises a lever 0| pivoted at one end on the bracket 94 and having its free end positioned to engage the head 91 of the plunger. Mounted intermediate the ends of the lever |0| is a follower roller |02 cooperating with a cam |03 fast on a shaft |08 journaled in a housing |05 mounted on the bracket 90. The shaft is arranged to bel driven by an electric motor M-I through the medium of speed reducing gearing of any suitable and well known type enclosed in the casing |05. The cam |02 as herein shown is formed with a single lobe |06 adapted to depress the lever |0| once in each revolution and thus shift the plunger 96 downwardly against the action of the spring 98. The cam and associated mechanism are protected by enclosure in a suitable housing 99 (Fig. l) of sheet metal or the like.

-Maximum pressure exerted by the tools on the work is determined by a relief valve V6, preferably of the adjustable type capable of being set as required for the Work being done. This valve, as herein shown, comprises a plunger |01 working in a cylinder |08 formed by a bore in the The cylinder |08 communicates at pressure duct 86 and the plunger when forced upwardly by the pressure fluid introduced through the passage uncovers a port`||0 in the side wall of the cylinder to by-pass excess fiuid through a` duct to the drain 11. Movement of the valve plunger is resisted by a compression spring ||2 interposed between the upper end of the plunger and the tip of an adjusting screw I3 threaded into a plug in the upper end of the cylinder. The pressure at which the valve opens can thus be regulated by turning the adjusting screw in one direction or the other.

In order to regulate the volume.of.uid delivthus control the rate at which the pressure exerted by the tools on the work is increased, suitable means is provided for varying the stroke of the plunger 96. This means, as herein shown, comprises an adjustable stop in the form of a screw I4 threaded into an L-shaped arm ||5 integral with the bracket 96 and overhanging the'free end of the lever |0|. The lower end of the screw engages lthe lever its upper limit position. Thus, by simply turning the screw in one direction or the other the swing of the lever vand therefore the stroke-of the plunger may be varied'.

as required. This adjustment is entirely indepen'dent of the various machine operations such as reciprocation and rotation of the tool hence. the rate at which the tool pressure is increased can be easily and accurately adjusted to meet the requirements o f any particular work.

A modified form of pressure fluid operated mechanism for actuating the tool expanding and contracting shaft 55 is shown in Figs. 6, 7 and 9 as comprising a plunger ||6 having at one end a piston ||1 working in a cylinder ||8 and at its other end a rack member I I 9 meshing with a segmental pinion |20 Iast on the shaft 65. The cylinder is preferably formed in a generally rectangular metal block or casing` |2| carried on the upper end of a ilanged bracket |22 adapted to be v coiled compression spring |25 yieldably urges the valve to toolv contracting position while a solenoid SOL-I acts, when energized, to operate the valve to its alternate position and initiate expansion of the tools.

In order to control the rate of which the abras1v e.elements of the tools are fed to the work, su1table means is provided for limiting the inward movement of the plunger H6 toa ser-ies of successively executed steps of predetermined length. The limiting means as herein shown comprises a stop member'or wedge |26 (Figs. 6 and 9) positioned adjacent the inner end of the plunger. The side of the Wedge facing the plunger is formed with aseries'of stepped surfaces |2l of progressively decreasing height from left to right as viewed in Fig. 9. Thesev surfaces or steps are adapted to be presented in the path of the plunge:` ||6 by shifting of the wedge in the direction of its length. For this purpose the wedge is movably supported on spaced rollers |28 (Fig. 6) journaled on the bracket |22.

In the operation of the mechanism, the high-l est step of the wedge, that is the step atv the" extreme left end of the wedge as viewed in Fig. 9,

is initially presented for engagement by thel plunger, thus imposing a minimum limit upon' its inward movement and the consequent eX- panslon of the tool at the beginning of the honing operation. As the honing operation proceeds, the wedge isshifted gradually to,present. successive lower steps in the path of the plunger which is advanced into engagement with such steps by the continued application of pressure to the outer end of the piston ||1. 'Ihe plunger therefore advances intermittently to rock the shaft 55 and thus progressively increase the pressure exerted by the tools on the work.

While any suitable means may be utilized for withdrawing the. wedge 4in the manner above described, the invention provides a novel presbore in the block |2| at one side of the cylinder H8. Working in the cylinder |3| vis a piston |32 having a piston rod |33 projecting from the cylinder substantially parallel to the plunger H6 and connected to the wedge |26 by Va suitable linkage for transmitting movements of the piston thereto.y This linkage as herein shown includes a link |34 connecting the outer end of the piston rod with one arm of a bellv crank lever l'pivoted at |36 on the bracket |22, the other arm of the'bell crank being connected with the wedge by a link |31.

As shown in Fig. 9, the cylinders A| L3 and |3| are connected at their outer and inner ends by passages |33 and |39. the ,latter being tted with a spring pressed ball check valve V-8 to permit fluid to flow in one direction only, that is from the cylinder ||8 to the cylinder |3|. This check valve is by-passed by an auxiliary Passage |40 in which is interposed a valve V-S havinga member in the form of an elongated rod |4| (Fig. 7) threaded into a plug |42 closing the end of an enlarged section |43 of the passage |40. The inner end of the member |4| ls tapered to coact with a similarly tapered seat formed at the junction of the passage |470 and the section |43 and it thus serves to determine the ow area of the passage. By reason of its threaded engagement with the plug, the valve member is readily adjustable to vary the flow of fluid from the cylinder |3|.

With the above arrangement the pistons H1 and |32 are quickly shifted to the outer ends of their respective cylinders, when the direction valve V--1 is set in its normal position to direct pressure iiuid to the inner end of the cylinder H8, the pressure fluid immediately passing into the cylinder |3| through the passage |39 and check valve V-8. Theiirst mentioned piston effects contraction of the tools and the latter advances the wedge |26 to present its highest step in the path of the plunger I 6.

Upon operation of the valve V-1 to its alternate position, pressure uid is directed into the outer ends of the cylinders ||8 and 3| to shift the pistons in the opposite direction. The piston ||1 advances rapidly until its movement is interrupted by engagement of the plunger with the highest step of the wedge |26. The piston |32 on the other hand, advances slowly since the pressure fluid -must be exhausted from the inner end of the cylinder through the restricted passage provided by the valve V-9, the valve V-8 effectively blocking the passage |39 under these conditions. Accordingly, the wedge |26 is withdrawn relatively slowly to present the successive steps in the path of the plunger ||6 which accordingly advances progressively as each succeeding step lsv-positioned in line with the plunger. The rate of plunger advance can be accurately controlled by adjusting the position of the valve member |4I. As this adjustment is entirely independent of any operation func.

tions of the machine, the rate of tool expansion, or in other words, the rate at which the pressure of the tools is increased can be closely coordinated with their metal removing action to insure maximum operating efficiency.

In placing the machine in operation, the work is secured in place on the work support and the, limit stopsl 30 and 32 are set to define the desired working stroke of the tools. Cams. |44 and |45 (Fig. 8) carried on a rocking Vcontrol rod |46 are positioned so that the latter is engaged by an arm |41 on the head when the tools have been fully inserted in the work. CamA |44 is set for engagement by the arm when the head moves beyond the upper limit of its Work stroke but before the tools are withdrawn from the work. Engagement of these cams by the arm serves to rock the shaft |46 about its axis to initiate certain control operations as will appear presently.

After the machine has been preliminarily set in the above manner, it is started by momentary action of a start switch S-I which energizes a pair of motor control relays R-I and R-2. Current is supplied to these relays and to other elements of the control system through a voltage reducing transformer TR connected toa power line L. Relay R|, when energized, closes its switch R-ll to connect the main driving motor M to the power line L. Relay R-2, when energized, closes switch R-2I to connect the booster pump motor M-I to the power line L. -The motor M drives the pumps P and Pa. The latter supplies pressure fluid to the-reversing valve V and the accumulator A.. The pump P delivers a supply of pressure iiuid to the cylinder 26 by way of a duct |46. A relief valve V2 of well known construction controls the pressure of the fluid. The pressure fluid is directed into the upper end of the cylinder by the valve V which is set in the position shown in Fig. 8 at the start of the operating cycle. 'I'he tool head and tools are accordingly moved toward the work.

'Ihe start switch is held in closed position until the head is moved out of its normal rest position at which time a holding circuit is completed for the relays R-l and )It-2 by energization of a latch relay R-3 to close a switch R3|. The energizing circuit for the latch relay is completed through a limit switch LS-l closed in response to the downward movement of the head through the usual stop bar |48 which rests upon a bracket |49 on the head when the latter is ln its rest position. The relays R-l and R-2 accordingly remain energized and continue the operation of the motors M and M-I until their holding circuit is interrupted either. by the opening of the switch R-3I or a manually operable stop switch S-2.

As the head continues its downward movement,

the intermediate stop 32 passes the pilot valve actuator 33 without operating the valve and when the tools have been fully entered in the work, the arm |41 engages the cam- |45 to rockA the control rod E46 and close a switch CS to energize a control relay R-4. This relay closes a switch R-4I to energize the clutch C and thus initiate rotation of the tools. A circuit is completed at the same time for an electrical timer T of any suitable and well known type which has previously been set to determine the with the work so that the major surface irregularities may be removed without subjecting the tools to excessive strains. As the honing operation proceeds the booster pump P| supplies successive impulses of pressure uid to the cylinder 66 to progressively increase the pressure exerted by the tools on the work so that they may function at maximum efiiciency throughout the honing cycle.

During the honing cycle the tools are traversed repeatedly from one end of the work to the other under control of the limit stops 30 and 32 which in well known manner actuate the pilot valve V-I to shift the direction valve V between its alternate positions. At the end of the honing cycle as determined by the timer T, the latter closes its switch TS to complete an energizing'circuit for a control relay R-5. This relay closes switch R-SI to energize a pull-out solenoid PS which in well known manner rocks the control rod 29 about its longitudinal axis to move the intermediate stop 32 toa position in which it is ineffective to engage the pilot valve actuating arm 33. The next upward stroke of the head therefore is'continued beyond the upper limit of the working stroke until the head reaches its limit position as determined by the upper limit stop 3l. When desired, the length of the operating cycle may be increased by actuation of a, manually operable push button switch S-3 connected in series with the timing switch TS. A cycle may be terminated at any time, of course, independently of the timer by closing a manually operable switch S-L Before the tools are withdrawn from the work the" arm It? engages the cam It@ and rocks the control rod |66 to open the switch CS and thus deenergize relay R-i. This relay, by opening switch R-i deenergizes the clutch C to interrupt the rotation of the tools and by opening switch 12b-d2 deenergizes solenoid SOL to return the valve V- to its normal position. 'I'he valve directs pressure iluid from the accumulator into lthe inner end of the cylinder 66, thus quickly contracting the tools.

'As the head approaches its upper limit position, limit switch LS-i is opened to interrupt the circuit for thelatch relay R-3 and this relay opens the 'holding switch R-l to deenergize the motor control relays R-l and R-Z. The machine is therefore brought to a complete stop with the various control elements in the position Ishown in Fig. 8 and in readiness for the start of the next operating cycle.

It will be apparent from the foregoing that the invention provides a honing machine of novel and advantageous character. The machine em-V -bodies novel means for expanding a plurality of honing tools simultaneously together with actuating means eiective to progressively increase the pressure exerted by the tools on the work as the honing operation progresses. 'I he tool expandingmeans is readily adjustable so that tool pressure may be accurately coordinated with the metal removing actions of the tools and thus enable the tools to operate at maximum efciency at all times. U

I claim as my invention: 1. A honing machine having, in combination,

a reciprocatory head, a plurality of hollow tool l tending transversely across the same adjacent the inner ends of the spindle, means providing an operative connection between the shaft and each of the actuator members effective when the shaft is rocked in one direction to expand the tools, a rack slidably mounted in the head for movement transversely of said shaft, a pinion fast on said shaft meshing with said rack, and power operated means for driving said rack.A

2. A honing machine having, in combination, a reciprocatoryv head, a plurality of tool spindles each journaled at one end in said head and adapted to carry on the other end an expansible and contractible honing tool, an vactuator for each tool including a member extending into the head, spring means yieldably holding the ac.

tuators in a withdrawn position to permit the tools to contract, means for shifting the actuators simultaneously to an operated position to expand the tools, `said shifting means including a shaft journaled in the head and extending transversely across the same above the tool spindles, means providing an operative connectionbetween said shaft and each of said actuators, a

pinion fast on said shaft, a plunger supported adapted to carry on the other end an expansible and contractible honingv tool, an actuator for each tool including a member extending into the head, means yieldably holding the actuators in a withdrawn position to permit the tools to centract, means for shifting the actuators simultaneously to an operated position to expand the tools, said shifting means including a shaft journaled in the head and extending transversely across the same above the tool spindles, cam means on said shaft engaging each -of said actuators, a pinion fast on said shaft, a rack coop,- erating with said pinion, and power operated means for driving said rack.

4. A honing machine having, in combination, a reciprocatory head, a plurality of hollonP tool spindles-each journaled at one end in said head and adapted to carry on the other end an expansible and contractible honing tool, a tool actuator extending from each tool through itsassociatedspindle and into the head, means yieldably holding the actuators in a withdrawn position to permit the tools to' contract, means for shifting the actuators simultaneously to an operated position to expand the tools, said shifting means v and adapted to carry on the other end an expansible and contractible honing tool, la tool actuator extending from each tool through its associated spindle and into the head, means yieldably holding the actuators in a withdrawn position to vpermit the tools to contract, means for shifting the actuators simultaneously to an operated position to expand the tools, said shifting means including a shaft journaled in the head and extending transversely across the same above the tool spindles, a rachet member fast on the provjecting end of each actuator, pinions on said shaft engaging said rack members, and powe actuated means for rocking the shaft. v

6. A honing machine having, in combination, a

support for an expansible and contractible honing tool, a support for work to be operated on by the tool, means for effecting relative rotation and simultaneous relative reciprocation of the tool and work, pressure fluid actuated means for expanding the tool into operative engagement with the work, a source of fluid maintained substantially at a predetermined pressure, means operative to direct pressure luid from said source to said tool expanding means to expand the tool into engagement with the work, and means perative to supply successive impulses of uid at a. higher pressure to said tool expanding means to progressively increase the pressure exerted by the tool on the work.

7. A honing machine having, in combination, a Support for an expansible and contractible honing tool, a support for work to be'operated on by the tool, means for eecting relative rotation and simultaneous relative reciprocation of the tool and work, pressure fluid actuated means for expanding the tool, a pressure fluid accumulator, means for connecting said accumulator to said tool expanding means to rapidly expand the tool into operative engagement with the work, said tool exerting a predetermined pressure on the work, and other means for delivering successive impulses of fluid to said tool expanding means' at a higher pressure than the fluid supplied from said accumulator to progressively increase the pressure exerted by the tool on the work.

8. A honing machinehaving, in combination, a support for an expansible and contractible honing tool, a support for work to `be operated on by the tool, means for effecting relative rotation and simultaneous relative reciprocation of the tool and work, pressure uid actuated means for expanding the tool,` a pressure fluid accumulator, a pump for delivering fluid to said accumulator at a predetermined pressure, means for connecting said accumulator to said tool expanding means to effect rapid expansion of the tool into operative engagement with the work, and a. booster pump interposed between the accumulator and said tool expanding means operative to effect a gradual increase in the pressure exerted by the tool on the work.

9. A honing machine having, in combination, a support for an expansible and contractible honing tool, a support for work to be operated on by the tool, means for effecting relative rotation and simultaneous relative reciprocation of the tool and work, a cylinder and piston mechanism for,

expanding the tool, a pressure fluid pump adapted to deliver a substantial volume of fluid at 'relatively low pressure, a second pressure fluid pump adapted to deliver a succession of impulses of pressure fluid at a substantially higher pressure, t

a pressure fluid Yline extending from said rst pump to said second pump, a second pressure fluid line extending from the second pump to the cylinder of said mechanism, and valve means interposed between said lines effective to permit pressure fluid to pass from said i'lrst pump to the cylinder to initially expand the tool into engagement with the work, said second pump acting thereafter to supply the pressure fluid to the cylinder in a succession of impulses effective to gradually increase the pressure exerted by the tool on the work.

10. A honing machine having, in combination, a support for an expansible and contractible honing tool, a support for work to be operated on by the tool, power actuated means for effecting relative rotation and simultaneous relative reciprocation of the tool and work, pressure fluid actuated means for expanding and contracting the tool, a source of pressure fluid, a pump, means for supplying pressure uid from said source to said actuating means and said pump, said actuating means operating initially to expand the tool against the work, and means connecting said pump with said actuating means to deliver successive impulses of pressure fluid from the pump to the actuating means for further expanding the tool lin incremental steps.

ALBERT M. JOHNSON.

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