US2377310A

US2377310A - Control mechanism for honing machines

Info

Publication number: US2377310A
Application number: US465556A
Authority: US
Inventors: Harry J Caldwell; Earnest Y Seborg
Original assignee: Barnes Drill Co
Current assignee: Barnes Drill Co
Priority date: 1942-11-14
Filing date: 1942-11-14
Publication date: 1945-06-05
Anticipated expiration: 1962-06-05

Description

n 1945- H. J. QALDWELL EI'AL I CONTROL MECHANISM FOR HONING MACHINES 7 Filed-Nov. 14, 1942 4JSheetS-Sheet 1 v Ear/1 June 1945- H. J. CALDWELL ETAL 2,377,310

CONTROL MECHANISM FOR HONING MACHINES Filed Nov. 14, 1942 4 Sheets-Sheet 2 arr a we iarne zi/ ebory June 5, 1945. H'. J. CALDWELL ETAL CONTROL MECHANISM FOR HONING MACHINES 4 Sheets-Sheet 3 S L-z Filed Nov. 14, 1942 il arryy a/a we urne t ebor- MTTQ'QQY;

June 5, 1945. H. J. CALDWELL ErAL CONTROL MECHANISM FOR HONING MACHINES Filed Nov. 14, 1942 4 Sheets- Sheet 4 3 a vw v W Sqor NVEN Patented June 5, 1945 UNITED STATES PATENT oF CONTROL MECHANISM FOR HONING MACHINES Harry J. Caldwell and Earnest Y. Seborg, Rockford, lll., assignors to Barnes Drill 00... Rockford, 111., a corporation of Illinois Application November 14, 1942, Serial No. 465,556 1 9 Claims. (Cl. 51-34 The invention relates to honing or lapping machines and more particularly to improved control mechanism for such machines.

The general object of the invention is to proabrasive tool or hone. In operation, the tool andwork arerelatively rotated and simultaneously relatively reciprocated while the tool is expanded to feed the abrasive elements thereof against the surface otthe work. Under production conditions, power actuated means is ordinarily utilized to efl'ect such expansion.

Accurate regulation of the pressure with which the tool is expanded against the work is essential for eflicient operation of a honing machine.- Thus, it insufilcient pressure is applied, the cutting efliciency of the tool is greatly reduced. On the other hand, application of excessive pressure results in the abrasive elements becoming loaded with particles of the material removed from the work ,which likewise reduces the cutting action of the tool. It is apparent therefore. that the maximum operating efllciency is attained when the tool is expanded at a selected intermediate pressure which enables it to remove stock at the maximum rate without undesirable load ins.

Application of higher pressure than the normal working pressure for short intervals is ordinarily not objectionable and under some condi tions may be advantageous. Thus. it the abrasive elements of the tool become loaded, a momentary increase in pressure tends to break down the loaded surface and restore the normal cutting action or the elements. Moreover, when the tool encounters a hard spot in the work. tool pressure .may be increased substantially abovethe normal working range while the tool is re-= moving the hard material. The same considerations apply when the tool is operating on a cOnstricted area or a workpiece. Under suchconditions the increased pressure enables the tool to remove the hard spot or to enlarge the constricted area to the required dimensions, provided, or course, that the expansion of the tool is suitably restrained while it is operating on ad- 'lacentareas or the. work.

With the above in view. an important obie'ct.

of the invention is to provide shovel and eillcient control: mechanism operative automatically to regulate the action or power actuated tool-expanding means in accordance with the rate or stock removal by the tool remains uniiorm.

whether or not that rate More specifically stated, the invention aims to provide control mechanism operative to restrain the power actuated tool expanding means as long as the tool operates to. remove stock at a normal predetermined rate and to temporarily withdraw the restaining means when the rate of stock removal lags, as when the tool encounters a hard spot in the work or when the abrasive elements become loaded with material removedirom the work, thereby increasing the pressure applied to the tool until normal operation is resumed.

Another object is to provide novel'control mechanism operative to maintain the tool expansion within predetermined safe limits when operating on workpieces-of non-uniform diameter or, in other words, to restrict tool expansion to the limits dictated by the areas of smallest diameter until such areas are enlarged to their proper-size. Still another object is to'provide an improved mechanism for controlling the rate of expansionof a honing tool or the like in timed relation to the rotation of the tool and to provide forcon I venient adjustment of the same for operating on work oi various materials and sizes.

Other objects and-advantages of the invention will become apparent; from the following detailed description or the preferred embodiment illustrated in the accompanying drawings in which:

Figure 1 is a fragmentary perspective view 01' a honing machine em in he invention 8 t eatures of t Fig. 2 is a sectional view illustrating diagrammaticallythe action or a honing tool on a. work piece which has been'warped or distorted from a true cylindrical form.

Fig. 3 is a sectional view showing diasrammatically the action or a honing tool on a workpiece in which a taper has been developed by a preceding operation.

Fig. 4 is ahorizontal sectional view of the reciprocatory head of the honing machine taken along the line of l4 of Fig. 1.

Fig. 5 is e. vertical sectional view of the head taken along the line 5-5 of Fig. 4.

Fig. 6 is a transverse vertical sectional view of the expansion control mechanism taken alon the line 8-6 of Fig. 4.

F18. 7 is a diagrammatic view showing the electrical and hydraulic circuits of the honing machine and their relationship to the mechanical elements of the machine.

1 Fig. 8 is a vertical sectional view 01 a honing machine head equipped with a modified iorm oi expansion control mechanism. I For purposes of illustration the invention has been shown as embodied in a vertical single spin-.- dle honing machine provided with pressure fluid operated hone expanding mechanism. It willbe understood, however, that the invention may be readily applied to other typesof honing machines uas well as to other machine tools having 'a comparable mode 01' operation. It will also 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 or the invention as expressed in the appended claims.

Referring to the drawings, the machine selected to illustrate the invention comprises an upright column Ill (Fig. 1) having at its upper end a forwardly projecting headframe l I. A stationary work support i2 (Figs. 1 and 7) is located directly below the headframe. Suitable guide members herein shown as cylindrical rods l3 are mounted on the face of the column in spaced; parallel relationto provide a guideway on which a head 15 may be reciprocated toward and from the work support. The head is arranged to carry an expansible and contractible honing tool IS on a tubular driver ll attached to a vertically disposed rotatably driven spindle l8. joumaled in the head.

A workpiece W, such as a metal block, havin a generally cylindrical bore B to be operated on by the tool it, is suitably clamped to the work support l2. The tool is supported in withdrawn position and guided into the work by a guide member is adjustably mounted on extensions of the guide bars I3. To traverse the tool through the bore of the work, the head it is reciprocated on its guideway. Such reciprocation of the head is effected, in the present instance, by a pressure fluid operated actuator comprising a vertically disposed cylinder 2| (Fig. 'i) mounted in the column I and having a working piston 22 connected by a rod 23 with a boss 24 rigid with the head and projecting rearwardly therefrom through a vertical slot 25 (Fig. 1) in the face of the column. Pressure fluid is supplied to the cylinder by a pump P through a system of valves and duets with associated control instrumentalities to be described hereinafter.

During its reciprocation pin the work the tool It is simultaneously rotated, such rotation being continuous in a honing operation and intermittent in a lapping operation. In the particular machine illustrated, continuous rotation is imparted to the tool by an electric motor M (Fig. 7) mounted on the column I 0. The motor is arranged to drive the tool through a train of gears 26 enclosed within the headframe II and a veras shown in Figs. and 'l. The gear is referably provided with a relatively long hub 29 which serves to maintain the driving connection with the splined shaft throughout the r p a n of the head.

the body. Springs or other suitable resilient means are arranged to yieldably urge the abrasive elements into their inner position in which the tool is contracted to minimum diameter so that it may be readily insertedin the work.

The tool is expanded by shifting the abrasive elements 86 radially outwardly ofthe tool body. This shifting is eiiected by means of cam devices of well-known construction enclosed within the tool body and operated by an actuating member 31 herein shown as a push rod extending through the tubular driver I1 and spindle l8 and operatively connected with a power driven actuator mounted in the toolhead ii. A coiled compression spring 38 encircling the push rbd and interposed between an internal shoulder formed in the spindle and a collar 39 fixed on the rod urges the rod upwardly to allow the tool to contract.

The actuator is, therefore, only required to shift An intermediateshaft 3|, journaled in the head IS with its axis substantially parallel to the axes of the splined shaft and the spindle, is arrangedto be driven by' the gear 28 through a pinion 32 fast on the intermediate shaft. .A gear 33, also rm on the intermediate shaft, mesheswith a pinion 34 keyed to the spindle. Any desired rate of rotation of the spindle and tool may be obtained by he use of gears of appropriate ratios in the gear train 24.

Honing or lapping tools used in machines of the type under consideration are what may be termed expansiblev and contractible abrasive tools.

For internal honing orlapping, the tool comprises a hollow generally cylindrical body 34 (Figs. 2, 3 and '7) on which a series of elongated abrasive elements 36 are mounted for movement radially of the rod downwardly to expand the tool.

While any suitable power driven actuator may be utilized for shifting the tool expanding rod, a pressure fluid operated actuator has been found to be particularly suitable for this purpose. In its preferred form .the actuator. includes a part movable in a predetermined direction to expand the tool. This part, as herein shown, comprises a plunger or ram having a. piston section 43 reciprocal in a cylinder bore 4 I- formed in a cylinder block 42. The cylinder block is bolted or otherwise rigidly secured to a horizontal web 43 in the head I5 with the cylinder bore substantially I in axial alinement with the tool spindle II. The

piston 40 is formed with an axial. downwardly opening bore 44 enclosing suitable anti-friction thrust bearings 45 adapted to receive the upper end of the tool expanding rod. The collar 33 on the rod provides a shoulder adapted to seat on the inner race ringof the bearing whereby the thrust of the piston maybe imparted to the rod without interfering with the rotation of the latter with the spindle. Pressure fluid is supplied to the actuator cylinder by a pump P (Fig. 7)

through a hydraulic control system to be described hereinafter.

Preferably, fluid is supplied to the actuator at a pressure which enables it to force the abrasive elements of the tool against the work with a pressure substantially above that required for normal operation and novel control mechanism' is provided for restraining the actuator so as to maintain the required tool pressure except under abnormal conditions during which a temporary incremental increase is permitted. Since the'piston 40 of the-actuator plunger is connected directly for expanding the tool the actuator restraining or control mechanism may be associated advantageously with the plunger. To this end, the piston section 40 of the plunger is formed with an extension or piston rod 48 (,Figs. 5 and 7) projecting upwardly through an aperture in the cylinder block 42 and through a sleeve-like hearing 41 forming part of a cap member 43 rigidly The upper end of the piston rod 46 is provided with a vertically disposed slot 43 dimensioned to accommodate abutment 'means indicated generally by the reference numeral lll.- -A' hardened wear strip 5| extending transverselyacross the upper end of the slot is arranged for direct engagement Y with the abutment means as will appear presently.

The abutment means ill, as shown in Figs. 4, 6 and 6, comprises an elongated flat-bar 42 projecting through the slot 48 and supported for movement substantially perpendicular to the path of movement of the piston rod 46. Support for the bar is provided in this instance by rollers 53 and 54 disposed on opposite sides of ,.the sleeve 41 stantlally centrally of the bar 52 la e wedge mem-' ber 58 presenting an inclined control surface for engagement by the wear strip I The wedge member 58, as shown in Figs. 5 and.

6, is generally T-shaped in cross section and the bar'52 is slit longitudinally to receive the depending flange of the member. A pin 59 extending through the bar and the flange of the member supports the latter for pivotal movement aboutv an axis perpendicular to the longitudinal axis of the bar whereby the angle of inclination of the control surface may be varied as required. In the form illustrated, the pivotal point of the bar is located adjacent its rearward end and the angle of inclination is controlled by an adjusting screw 60 threaded into the forward end of the bar 52 and engaging an inclined cam surface formed on the fiange of the wedge member. A lock nut 6| threaded onto the adjusting screw-acts to hold the parts in adjusted position.

It will be evident from the foregoing that the extent of movement of the actuator plunger and, therefore, the degree of expansion of the tool l6 as well as the pressure with which it is applied to cient operation due to the restraining action of the abutment means.

The mechanism for electing the periodic shifting of the abutment means above referred to comprises spring means arranged to yieldably urge the abutment bar 52 in a direction to interpose the highest point of the inclined control surface in the path of the wear strip II and cooperating abutment shifting mechanism operative to shift the abutment bar step-by-step in the opposite direction. In order to prevent binding of the abutment bar in its bearings, the spring means acting thereon consists of two tension springs 62 arranged on opposite sides of the bar, each anchored at one end to the casing of the toolhead, as by an eyebolt II, and at the other end to a transverse rod extending through the the work will depend upon the range of movement permitted by the disposition of the control surface of the wedge member 58 with respect to the wear strip 5|. Moreover, the maximum rate at which such movementmay proceed is dependent upon the rate at which the control surface is caused to recede from the path of the wear strip.

The rate of such recession may be varied, either H by changing the angle of the wedge member or by changing the rate of advance of the bar 52 '40.

upon which the member is mounted. Accordingly, an extremely wide range of adjustment is obtainable to adapt the machine for operating on substantially any material capable of being finished 'by a honing or lapping process.

-work of any size within its capacity and upon '45 l the right.

control surface to its original restraining position advanced position, springs. 52 will draw it rear- The tool is accordingly subjected to the full pressure of the actuator when operating on the hard spot or the constricted area while the abutment means assumes control and limits expansion during the traverse of the tool over the remainder of the work.- In this way, the tool is enabled to fi nish the work to-uniform diameter .without subjecting the abrasive elements to excessive pressure at. any time. Moreover, during normal op- 'eration,-the.rate of expansion of the tool and therefore the pressure exerted by-it as the work is maintained at the level required for most efflbar 52 adjacent its forward end.

A preferred form of abutment shifting mechanism is shown in Figs. 4 to 7 of the drawings. This mechanism comprises a pawl ll pivotally supported by a pin II between a pair of spaced members 12 forming one arm of a bell crank lever 13 rockably supported on the pin which carriers the roller 52. The members 12 are positioned so as to straddle the bar 52 and a spring 15 encircling the pin H acts to yieldably hold the nose of the pawl in engagement with suitable ratchet teeth 15 cut in the upper face of the bar adjacent its rear end. The other arm of the bell crank 13 carries a follower roller I5 positioned to coact with a cam 11 fast on a camshaft ll journaled in the head l5. The cam shaft is driven in timed relation withthe rotation of the tool spindle from their:- termediate shaft ii; For this purpose a cross shaft 19. .journaled in the head, carries a gear 80 meshing with the pinion Ii fast on the cam shaft. Also fast on the cross shaft is a worm wheel 82 engageable with a worm II keyed to the intermediate shaft 3|.

Rotation of the cam II from the position shown in Fig. 5 through one-half of a revolutionis effective to rock the bell crank 13 in a counterclockwise direction, and through the action of the pawl ii, the abutment bar 52 is shifted one step to the left. Upon rotation of the cam through the remainder of its revolution the bell crank is rocked 'back to its normal rest pos tion by a spring-pressed pin l thus carrying the pawl to I If the abutment bar is held in the advanced position during this return movement of the pawl, the nose of the pawl will slip over the adjacent ratchet tooth and thereby condition the mechanism for advancing the bar another step in the succeeding revolution of the cam. However, if the abutment bar is not held in this wardly with the pawl upon the return movement of the latter.

In order to coordinate the positioning of the abutment bar with the operation of the actuator and thus with the expansion of the tool, engagement of the wear strip H with the control surface of the wedge member 58 is utilized to perform the holding function above referred to. In operation thebar 52, when advanced a step in the manner above explained, withdrawsthe control surface a predetermined distance from the wear strip 5|,

thus freeing the actuator plunger for limited movement at an accurately controlled or restrained rate in a direction to further expand the tool I6. If such movement occurs, a it normally will when the tool removes therequired amount of stock from the work, the plunger will advance sui'iiciently to bring the wear strip into contact with the new area of the control surface presented thereto and the wedging action resulting from the engagement of these parts will act to hold the abutment bar in advanced position while the pawl returns to pick up the adjacent ratchet tooth.

Progressive advance of the abutment bar proceeds as long as the actuator plunger continues to follow up the receding control surface of the wedge member 58. In other words, the actuator advances as long as the tool continues to remove stock from the work andito expand at the predetermined rate for which the control mechanism is adjusted. Upon failure of the tool to-perform its cutting function at the normal rate, expansion will lag and the control surface will, therefore, separate from the coacting part of the actuator when the abutment bar is advanced. In the absence of engagement between the wear strip and the control surface, the abutment bar will return with the pawl 1i upon its retraction, thus preventing the pawl from slipping into the next adjacent ratchet tooth. Accordingly, the abutment bar will simply reciprocate idly during the interval required for tool expansion to catch up. 'Under these conditions, the abutment means has no restraining eifect on the actuator plunger hence, the full pressure of the actuator is temporarily applied to the tool. When the tool eventually removes sufllclent stock to permit the desired advance of the actuator plunger, the abutment means again exercises its control function and progressive advance of the abutment means is resumed.

Coordination of tool expansion with the cutting action of the tool is particularly advantageous in honing workpieces that have become warped or in which a slight taper has been generated in a preceding operation. Thus, in honing a workpiece wr which has become warped so as to leave a slight constriction at a point X in the bore B1, as shown in exaggerated form in Fig. 2, expansion of the hone is confined within the limits dictated by the constricted section or the bore. As a result, little or no stock isremoved from the larger sections of the bore until the constricted area has been -enlarged by the action of the tool. In this way a straight, uniform bore is produced without requiring manual adjustment of the tool or other interventions by the machine attendant.

The control mechanism functions in'the same manner in honing tapered bores such as the bore Ba of the workpiece W: shown in Fig. 3. In this instance, expansion of the hone is determined by the rate of removal of stock from the smaller end of the bore until the bore becomes substantially cylindrical throughout its entire length. There may be occasions in which the pawl II will slip over the adjacent tooth while the tool is in the larger section of the bore, but such instances are infrequent and the increment of expansion permitted in any one cycle is so small that its effect is negligible. Moreover, such premature advances of the abutment means are automatically compensated for by delaying the advance in the next operating cycle. In general, the expanding increments of the tool average up so that the restricted section of the bore is finished to the desired dimensions without subjecting the adjacent areas of the work to' excessive tool actions.

Means is provided for disengaging the pawl ll from the ratchet teeth l! at the end of a honing cycle to permit full retraction of the abutment barto its starting position. This means, as herein 'shown, comprises a pawl throwout lever ll pivoted intermediate its ends on a pin 81 carried be tween extensions of the flanges 51 of the cap member. One end of the lever is positioned for engagement with a tail piece 88 projecting rearwardly from the pawl ll while the other end of the lever carries an adjustable contact screw 89 positioned 'for engagement by the top of the plunger 46 and normally held in contact therewith by a spring 90 acting on the lever. When the supply of pressure fluid is cut off fromthe actuator cylinder and the actuator plunger is raised by the action of the spring 38, the piston rod acts to rock the lever 86 in a direction to withdraw the nose of the pawl from engagement with the ratchet teeth and thus free the abutment bar for return by the springs 62.

Suitable means is also provided for enabling the attendant to withdraw the pawl from the ratchet teeth at any point in the operating cycle so that the tool may be traversed through the work in a series of polishing strokes if desired. For this purpose, the end of the lever adjacent the contact screw is connected by a link 9| with one arm of a bell crank lever 82, the other arm of the bell crank lever being connected with the armature of a solenoid SOL-l (Figs. 5 and 7). The arrangement is such that energization of the solenoid is effective to roek'the lever in a clockwise direction (as viewed in Fig. 5) and thus lift the nose of the pawl out of engagement with the ratchet teeth. Energization of the solenoid may be controlled in any suitable manner as by a push button. switch S-l (Figs. 1 and 'l) conveniently located on a switch panel at the front of the machine.

The movements of the abutment bar 52 are additionally used to advantage in controlling the length of the working cycle of the machine. To this end a limit switch LSI, suitably arranged in the control circuit for terminating a working cycle as will be described presently, is mounted on the-front wall of the head l5 for actuation by the bar. The particular switch employed in the exemplary machine is of the normally open type adapted to be closed by actuation of a pivoted switch arm (Figs. 5 and '7) which is arranged to depress a push button 88 operatively associated with the switch contacts. .The switch arm is provided at its free end with a contact roller 91 engageable by the adjusting screw 60 carried on the end of the bar 52. A suitable housing 88 (Figs. 1, 4 and 5) mounted on the front wall of the head encloses the limit switch and associated parts. is conditioned upon progressive expansion of the tool to the finished diameter of the work, it will be apparent that the parts may be adjusted so as to close the limit switch and terminate the work-' The structural elements'of the machine and actuator and many of those comprising the-control mechanism are identical with elements previously described and are therefore identified by, the same reference characters. Non-identical elements are identified by the reference character of their functional counterpart with the suiiix (1 added.

Referring now to Fig. 8, it will be observed that the abutment means 50- includes a shiitable bar II. which differs from the bar 52 in that itispro- Since the advance of the abutment bar vided with rack teeth Hill on its lower surface. These teeth are engaged by a pinion IM fast on a shaft which ,replaces the roller supporting pin 58 of the structure shown inFig. 5. Shaft -58& has a gear I02 meshing with a pinion I03 fast on a shaft 189. corresponding generally to the cam shaft 78. Shaft 189.,i1'1 turn, has a gear 8 la mesh ing with a pinion 80s. on the cross shaft 19 which, as previously explained, is driven from the intermediate shaft 3i by the worm 83 and worm wheel 82.

Rollers 53 and 54 are provided, as in the previously described form, for supporting the abutment bar 528. In the present instance, however, these rollers perform their supporting function only when the actuator is operating to expand the tool and the wear strip 5! is in engagement with the control surface of the wedge member as. When the actuator plunger is in the retracted position, the abutment bar is lifted-from the rollers by plungers wt and I05 seated in recesses in the cap member t8 and urged upwardly by compression springs Hi8 and ml. The lifting of the abutment bar disengages the rack teeth I00 from the pinion we, thus freeing the bar for retraction by the springs as.

The advance of the abutment bar 529, may be utilized to terminate the working cycle of the machine by actuation of the limit switch LS;l as before explained. In this instance, however,

since the bar is positively advanced in timed relation with spindle rotation the timing of the working cycle is directly coordinatedwith such rotation of the spindle and the tool. I

The operation of the hydraulic and electrical control system and associated control instrumentalities will be readily understood by reference to 7 of the drawings. In the particular machine selected to illustrate the invention, the mechanical portion of the control system is similar to that disclosed in the Holland Ratent No. 2,255,583, granted September 9, 19411; Briefly stated, with this system of control the reciprocating movementsof the head 15 are transmitted through an endless chain I In to a rotary on oscillatory control mechanism indicated generally at HI. This mechanism is arranged to impart appropriate rocking movements to a control shaft H2 which actuates a pilot valve V-l to selectively position a reversing valve V-2 for direc in fluid from the pump P to either the upper-or lower end of the cylinder 2! as required. The valve V--2 additionally connects the opposite end of the cylinder 2 l to a drain line H3 which returns the fiuid exhausted from the cylinder to a tooth the pump and the cylinder to the drain; line 80%. As herein shown, the valve V-3 is arrangedv to be operated-by a solenoid SOL-2. A relief valve H5 controls the pressure or the fluid dellvered by the pump P. a

The machine is started in operation by closure of a push button cycle start switch S2 which completes an energizing circuit for a running relay R-l. Relay R-l, when energized closes switches a-n, a-lzsnd a-|a. The firstmentioned switch starts the motor M which drives the spindle 18. Switch Ri -I2 completesa circuit for a second running relay R-2 which, by closing a switch R-Il, starts the motor M arranged to drive the pumps P and P. Closure of switch R-IB prepares a holding circuit for the running relays.

At the beginning of an operating cycle the head it is in its upper position and the control mechanism is effective to set the valve V -2 in a position to directfiuid to the upper end of the cylinder 28. Consequently, the starting of the pump P results in the immediate movement of the toolhead id downwardly. The starting switch 8-6 is held closed until the movement of the head is suflicient to effect closure of a limit switch me which completes the holding circuit for the running relays by way of relay switches R-li and R-lt, normally closed, inching switch S-S, and normally closed stop switch 8-5. For purposes of illustration the limit switch LS2 has been shown arranged for direct actuation by the toolhead, but it will be appreciated that this switch may be actuated by the rotary control mechanism a i i if desired. In either-case, the running relays are maintained energized to continue the working cycle of the machine after the starting switch S2 is released.

The operation of the machine can be interrupted at any time by opening the stop switch se to release the running relays. 'Also, the pump. motor M may be started and reciprocation of the toolhead initiated independently of the cycle starting switch by actuating the push button of the inching switch to open switch S-3 and close switch S5. Under these conditions relay R--l is not energized due to the open condition of relay switch Rl 2 and the tool spindle is therefore not rotated. However, the head IE will be reciprocated as long as the switch 8-5 is held closed,

thus providing a convenient means for adjustingthe tool and work in the initial set up of the machine. q

Upon movement of the head l5 sufliciently to enter the tool in the work, a limit switch 18-3 is closed, preferably by the rotary'control mechanism HI. Closure of that switch completes a circuit for a control relay R-3 which closes a switch R-3l to energize the solenoid SOL-2. As previously explained, this solenoid, when energized, shifts the control valve V-3 into a position to direct pressure fluid to the tool expanding cylinder it. The tool is thus expanded automatically upon its entry into the work. Tool expansion is held to a minimum at the beginning of the cycle and allowed to increase progressively at an accurthe cylinder and infanother position to connect ately controlled rate by the abutment means of the, expansion control mechanism previously descrihed.

\ ts will be seen by reference to the Holland patent, the control mechanism is so arranged that the reciprocation of the. head is normally confined within predetermined working limits until the control action is modified so as to per-' mit movement of the head beyond the upper limit of the working stroke to the fully retracted position in which it is shown in Fig. '1. Such modification-is eiiected in the present instance by closure of the limit switch LS-i to complete a circuit fora control relay R--& which, in turn, closes a switch R4l to energize a control modifying solenoid SOL-3. The solenoid operates,

valve V -2 at the upper end of the working stroke and thus permit the head to return to its upper limit position and withdraw the tool from the work.

As the head returns to its fully retracted position, limit switch LS2 is opened, thus deenergizing the running relays R-l and R-2 and stopping the machine with the tool separated from the work. Prior to its withdrawal, the tool is contracted due to the opening of the limit switch -3. If it is desired to continue the reciprocation of the tool in the working cycle independently of the limit switch 1Sl, an auxiliary switch S-B may be opened manually to prevent energization of control relay R-3. I Moreover, the relay may be energized at any. time during the working cycle of the machine by closure of a manually operable switch S--'|.

Itwill be apparent from the foregoing that the invention provides a control mechanism of novel and advantageous character. particularly suitable for honing or lapping machines. The control mechanism maintains the tool expanded at the most eflicient working pressure during normal operation and automatically effects an increase in tool pressure when the cutting action lags. Pressure increase is accurately controlled and expansion of the tool is limited to relatively small increments so that excessive expansion is eifectually prevented when the tool is operating on irregular bores. Moreover, the improved mechanism is adapted to automatically regulate the length of a working cycle of the machine and terminate the cycle when the work is finished to the desired dimensions. The control mechanism is simple in construction and is readily adustable to adaptthe machine for operating upon work of any size within the capacity of the machine and upon any material capable of being finished by honing or lapping processes.

The invention also provides novel means for timing a working cycle in accordance with the rotation of the honing tool. The mechanism utilized for this purpose additionally acts to control the rate of hone expansion so as' to insure the most efllcient operation of the machine.

We claim as our invention:

1. In a honing machine, in combination, means for supporting an expansible abrasive tool, means for supporting work' to be operated on by the tool, power actuated means for relatively rotating and simultaneousLv relatively reciprocating the tool and work supports through a working cycle, an actuator including a part movable in a predetermined direction to expand the tool into operative association with the work during the working cycle of the machine, an abutment member having a control surface engageable by said part and eflective to restrain the movement thereof in said predetermined direction, means operable periodically to shift said member so as to cause the control surface to recede from said part in incremental steps, yieldable means tending to retract said member after the shifting thereof, said member being held in shifted position by engagement of said part with the control surface when the tool has removed sufllcient stock from the work to permit a corresponding incremental advance of said part whereby the periodically operating means is conditionedto shift the member an additional step, means operative to vary the rate atwhich said member is shifted by said periodically operable means, and other means for varying-the length of the incremental receding steps of the control surface produced by the shifting of said member.

2. In a honing machine, in combination, means for supporting an expansible abrasive tool, means for supporting work to be operated on by the tool,.power actuated means for relatively rotating and simultaneously relatively reciprocating the tool and work supports through a working cycle, an actuator including a part movable in a predetermined directionto expand the tool into operative association with the work during the working cycle of the machine, an abutment member having a control surface engageable' by said part and eflective to restrain the movement thereof in said predetermined direction, mean operable periodically to shift said member so as to cause the control surface to recede from said part, in incremental steps, yieldable means tending to retract said member after the shifting .thereof, said member being held in shifted position by engagement of said part with the control surface when the tool has removed sufficient stock from the work to permit a corresponding incremental advance of said part whereby the periodically operating means is conditioned to shift the member an additional step, and means for driving said periodically operable means in timed relation to the relative rotation of the tool and work supports.

3'. In a honing machine, in combination, means for supporting an expansible abrasive tool, means for supporting work to be operated on by the tool, power actuated means for relatively rotating and simultaneously relatively reciprocating the tool and work supports through a working cycle, an actuator including, a part movable in a predetermined direction to expand the tool into operative association with the work during the working cycle of the machine, an abutment mem- 40 ber having a control surface engageable by said part and effective torestrain the movement thereof in said predetermined direction, means operable periodically to shift said member so as to cause the control surface to recede from said part in incremental steps, yieldable means tending to retract said member after the shifting thereof, said member being held in shifted position by engagement of said port with the control surface when the tool has removed sufficient stock 9 from the work "to permit a corresponding incremental advance of said part whereby the periodically operating means is conditioned to shift the member an additional step, and means for adjusting the position of said control surface to regulate the length of said incremental receding steps.

4. In a honing machine, in combination, means for supporting an expan sible abrasive tool, means for. supporting work to be operated on by the tool, power actuated means for relatively rotating and simultaneously relatively reciprocating the tool and work supports through-a working cycle, an actuator. including apart movable in a predetermined direction to expand the iool into operative association with the work during the working cycle of the machine, an abutment-member havingja control surface engageable by said part and effectiveto limit the movement thereof in said predetermined direction, means operable periodically to shift said member so as to "cause the control surface to recede from said part in incremental steps. yieldable means'tending to retract said member after the shifting thereof, said member being held in shifted position by engagement of said Dartwith the control surface '75 when the tool has removed sumcient stock from the work to permit a corresponding incremental advance of said part whereby the periodically operating means is conditioned to shift the member an additional step, and control means operable manually to temporarily disable said periodically operable means and thereby interrupt the expansion of the tool by said power actuated means.

5. A honing machine having in combination, relatively reciprocable tool and work supports, a tool spindle journaled at one end in said tool support and carrying at its other end an expansible and contractible honing tool, a tool actuator extending through said spindle to said tool, said actuator being operative upon movement in one direction to effect expansion of the tool and upon movement in the other direction to efi'ect contraction of the tool, pressure fluid actuated means including a piston reciprocable within a cylinder, said piston being operatively connected with said actuator and operative to impart movement thereto in at least said one direction, a rod movable with said piston and having a transversely disposed slot positioned externally of the cylinder,

an abutment member extending through said slot,

said member presenting a control surface engageable by said rod to limit the extent of move ment of said piston in said one direction, and means for shifting said abutment member to cause the control surface to recede from engagement with said rod and thereby permit additional movement of said piston.

6. A honing machine having in combination, relatively reciprocabletool and work supports, a tool spindle journaled at one end on said tool support and carrying at its other end an expansi: ble and contractible honing tool, a tool actuator extending through said spindle to said tool, said actuator being operative upon movement in one direction to eifect expansion of the tool and upon movement in the other direction to effect contraction of the tool, pressure fluid actuated means including a piston reciprocable within a cylinder, said piston being operatively connected with said actuator and operative to impart movement thereto in at least said one direction, a rod movable with said piston and having a transversely disposed slot positioned externally of the cylinder, an abutment member extending through said slot adapted to coact with said rod to limit the movement of said piston in said one direction, and means for adjusting the position of said abutment member with respect to said rod. ,7

7. The combination with an actuator movable in one direction to effect expansion of a honing tool or the like, of an abutment member shiftable transverselyof said actuator and having a control surface disposed at an angle to the path of movement oi. the member, a contact-element carried by said actuator and engageable with 8. In a honing machine, in combination; "a rotatably supported tool spindle adapted to carry an expansible and contractible honing tool. power means for driving the spindle, a tool actuator extending through the spindle to the tool, means yieldably urging said actuator in a direction to effect contraction of the tool, means including a reciprocable plunger operative to urge the actuator in the other direction to effect expansion of the tool, abutment means shiftable relative to said plunger and having a control surface positioned to limit the extent of movement of the plunger in said other direction, said control surface being inclined at an angle to the path along which the abutment means is shiftable so as to. permit varying degrees of movement of the plunger in difierent shifted positions of the abutment means, and mechanism driven from-said spindle driving means for shifting said abutment means in timed relation to the rotation of said spindle.

'9. In a honing machine, in combination, a rotatably supported tool spindle adapted to carry an expansible and contractible honing tool, power means for driving the spindle, a tool actuator extending through the spindle to the tool, means yieldably urging said'actuator in a direction to effect contraction of the tool, means including a reciprocable plunger operative to urge the actuator in the other direction to effect expansion of the tool, a rod reciprocable with said plunger. abutment means shiftable relative to, said plunger and having a control surface positioned to limit the extent ofmovement of the plunger in said other direction, said control surface being inclined at anangle to the path along which the abutment means is shiftabl'e so as to permit varying degrees of movement of the plunger in different shifted positions of the abutment means. pawl and ratchet mechanism operative to shift said abutment means step-by-step, and means operatively connecting said mechanism with said spindle driving means. 1

10. The combination with a member movable in one direction to eflect expansionof a honing tool or the like. of abutment means shiftabletransversely of the path of said member and having an inclined control surface effective in different shifted positions of the abutment means to variably limit the extent of movement of the j member, means yieldably urging said abutment mined extent acting to hold the abutmentmeans.

said control surface to limit theextent of movement of the actuator, ratchet teeth formed on said abutment member, a periodically "reciprocated pawl disposed for cooperation with said ratchet teeth, said pawl coacting in its forward movement with one of said ratchet teeth to advance the member a predetermined distance and thereby cause the control surface to recede from return movement when said element engages the control surface whereby said pawl is conditioned "to cooperate with a succeeding ratchet tooth for further advancing said member.

in the shifted position against the action of said yieldable means whereby .to condition said periodically operable means for shifting the operative means a stepfarther from the rest position.

11. The combination with a member movable v in one direction to eifect expansion of a honing tool or the'like, of abutment means shiftable transversely of the path of said member having,

aninclined control surface engageable by the member tovariably limit the extent of movement thereof in different shifted positions of the abutment means, means operative to advance: the -abutment means stepby-step in a direction advancing step, said member upon completion of its incremental movement acting to'hold the abutment means in advanced position against the action of said other means whereby to condition said mechanism for advancing the abutment means another step.

12. The combination with an actuator movable in one direction to eifect expansion of a honin tool or the like, of an abutment member shiftable transversely of said actuator and having a control surface disposed at an angle to the path of movement of the member, a contact element carried by said actuator and engageable with said control surface to limit the extent of movement of the actuator, pawl and ratchet mechanism operable periodically to advance said member through a step effective to cause said control surface to recede ,a predetermined distance from said contact element, and means tending to retract said mem,

ber'after each step, said member being'held-in advanced position between steps only when the actuator is advanced sumciently to effect the re engagement of said element with the control surface.

13. 'Actuating mechanism for honing tools and the like comprising, in combination, a part movable in one direction to eflect expansion of the tool. power actuated means adapted to urge said part in said one direction, a member having a control surface positioned for coaction with said part to limit the extent of movement thereof,

- means operative to shift said member and present successive areas of said surface for coaction with said part, said surface being inclined at an angle to the pathv of the member so as to permit a progressive advance of-said part in response to the movements of said member, and means operative to adjust the angle of said surface with respect to the path of the member.

14. Actuating mechanism for honing tools and the like comprising, in combination, a reciprocatory plunger, shiftable abutment means for limiting the movements of said plunger in one direction, said abutment means including an inclined control surface effective to permit movement of the plunger through varying distances in the different shifted positions of the abutment means, and means for adjusting the angle of inclination of said control surface to determine the extent of movement of the plunger in said different shifted positions of the abutment means.

15. The combination with means for relatively rotating andsimultaneouslyrelatively reciprocating a power expanded honing tool and a workpiece, of control means operative to interrupt such relative rotation and reciprocation upon removal of a predetermined amount of stock from the workpiece, said control means includinga mem-'- ber movable through a distance proportional to the degree of expansion of the tool,.a second member having a control surface positioned for engagement by said first member, means for intermittently shifting said second member to cause the control surface to recede from the first member in incremental steps,-said first member acting to hold the second member in shifted position by engagement with said control surface between successive shifts of the second member, and a controller actuated in response to the movement of said second member to a selected limit position.

16. In a honing machine. in combination, means for supporting an expansible abrasive tool,'means for supporting work to be operated on by the tool, power actuated means for relatively rotating and simultaneously relatively reciprocating the tool and work supports through a working cycle, an actuator including a part movable in a predetermined direction to expand the tool into operative association with the work during the working cycle, an abutment member having a control surface engageable by said part and effective to limit the movement thereof in said predetermined direction, means operable periodically to shift said member so as to cause the control surface to recede from said part in incremental steps, yieldable means tending to retract said member after the shifting thereof, said member being held in shifted position by ens sement of said part with the control surface when the tool has removed sufficient stock from the work to permit a corresponding incremental advance of said part whereby the periodically operating means is conditioned to shift the member an additional step. and means actuated by said member upon being shifted through a predetermined number of steps for interrupting the working cycle. 17. The combination with an actuator movable in one direction to effect expansion of a honing tool or the like, an abutment member having an inclined control surface positioned to block the movement of the actuator in said one direction, means for shifting said member to cause the control surface to recede from the actuator, said shifting means including a driven pinion, rack teeth on said member adapted for coaction with said pinion, and means acting on said member to hold the rack teeth out of engagement with said pinion, said last mentioned means being yieldable to permit movement of the member for effecting engagement between the rack teeth and the pinion in response to the initial movement of the actuator in said one direction.

18. In a honing machine, in combination, a rotatable spindle adapted to support an expansible honing tool, power actuatedmeans for driving means normally acting to hold said rack teeth out of engagement with the pinion, said holding means yielding to permit engagement between the rack teeth and pinion in, response to movement of the actuator member in said one direction.

19. The combination with a movable actuating member for effecting the expansion of a honing tool or the like, of power actuated means for moving said member, a shiftable abutment member adapted to variably limit the extent of movement of said actuating member by said power actuated means said abutment member coacting with said actuating member to permit progressive incremental advances of the latter as said abutment member is shifted step-by-step away from a normal'rest position, and periodically operat- HARRY J. CALDWELL. EARNEST Y. SEBORG.