US2167758A - Method and machine for honing cylindrical surfaces - Google Patents

Description

g- 1 A. M. JOHNSON ET AL 2,167,758

METHOD AND MACHINE FOR HONING CYLINDRIGAL SURFACES Filed March 18, 1938 2 Sheets-Sheet l NTOIQS M/berf 27% (70/5/290)? QM/fek &

Aug. 1, 1939. I JOHNSON ET AL 2,167,758

METHOD AND momma FOR HONING CYLINDRIGAL suamcms Filed March 18, 1938 2 Sheefs-Sheet 2 DECREASE;

START .l1 STOP SL3 20 pressure on the surface being dressed is varied in pp nd d cla ms.

Patented Aug. 1, 193a a 2,167,758

UNITED STATES PATENT OFFICE" METHOD AND MACHINE FOR 'HONHIG CY- LINDRICAL SURFACES Albert Johnson and Walter M. Fairbairn, Rockford, Ill., assignors to Barnes Drill (30., Rockford,-lll., a corporation of Illinois.

Application March 18, 1938, Serial No. 196,636

18 Claims. (Cl. 5134) The invention relates to the art of dressing The features of the invention may be emcylindrical surfaces and more particularly to an bodied in various types of machine tools and improved machine for and method of dressing are particularly suitable for-use in machines for such surfaces by a honing or lapping operation. dressing cylindrical surfaces by a honing or lap- The primary object of the invention is to imping process in which a cylindrical abrasive tool prove th efiiciency of the honing operation, to or hone is rubbed over the'surface of the work reduce the amount of power required in the inipiece by a combination of movements including tial sta'geof the operation, and to increase the relative rotation of the tool and work and relauseful life of the tools employed in carrying out tive axial reciprocation'of the tool and work.

the operation. f For purposes of illustration, the invention is to Another object of the invention is to provide a herein-disclosed embodied in a honing machine in new and improved method of honing cylindrical which the tool is rotated and reciprocated relasurfaces in which the removal of irregularities tive to a stationary work piece. It is to be underleft on the surface by a preliminary boring or stood, however, that the invention may be apgrinding operation and the dressing of the surface plied to other types of honing d pp to a true contour and smooth finish are carri d chines and is in nowise limited to the specific form out in separate steps. or environment disclosed but embraces all modi- Another object is to provide an improved methfications. adaptations and alternative construcod of honing cylindrical surfaces in which tool tions Co Within e Sp and Scope of the different stages of the honing operation. o g machines have re t y become a Another object is to provide an improved honable in which the expansion of the tool is effected ing machine embodying novel tool-actuating u cally. For many p p these mar means and controls therefor whereby the honing chines represent a distinct improvement over prior tool'may be actuated in a series of steps in each machines employing spring-expanded tools since 25 of which a different degree of pressure is apthey provide a uniform tool pressure throughplied to the surface of the work piece by the out the honing operation, whereas with aspringtool. expanded tool,.the tool pressure is at its maximum Another object is to provide an improved maat the beginning of the operation and gradually 3O chine adapted for rough and finish honing in decreases as the diameter of the work increases. 0 which the duration of the different operations is In either case, the amount of pressure that can controlled by timing means. I be applied with safety isdetermined by the abil- Another object is to provide in a machine of ity of the tool to withstand the strain imposed the above general character a novel and efliby its initial engagement with the rough surface cient arrangement of electrical and hydraulic cirof the work piece. Accordingly, when the tool is 35 cults and controls therefor by which the 'operaexpanded within safe limits of pressure at the tion of the machine may be conveniently conbeginning of the Ope i n, it s a y Operates trolled from a single central station. below its maximum efliciency after the major Still another object is to provide an improved irregularities have been removed from the sur- 40 electrical control system for controlling the operface with attendant decrease in the resistance 40 ation of a honing machine. offered to the rotation of the tool.

A further object is to provide novel means for The present invention aims to overcome the reversing the rotation of the honing tool during foregoing difficulties by providing means ofa the honing p a io novel and advantageous character whereby the Other objects and advantages of the invention pressure with which the toolis applied to the sur- 45 will become apparent from the following detailed face of. the work may be varied as required. description of the preferred embodiment illus- Thus, in honing. workwhere the surface is in a trat'ed in the accompanying drawings, in which: very rough condition, the tool may be applied to Figure l is a diagrammatic view showing the the-surfacewith a relatively light pressure for an relationshp of the variousmaohine elements and interval suflicient to remove the major virregular- 50 the associated hydraulic-actuating and control ities. In this roughing operation, the surface is means. 4 I smoothed ofi somewhat so that resistance to the Fig. 2 is a schematic diagram showing the electool is decreased substantially. Accordingly, the trical circuits and apparatus comprising'thc imnext step or finishing operation may then be 5 proved electrical control systems carried out with increased tool pressure to encontrolling the duration of the diflerent operating stagesautomatically. This means comprises suitable timing devices, preferably electricallyoperated, with appropriate control apparatus whereby each stage is terminated after a predetermined time. The timing *devices, of course,'

are adjustable so that the length of each operating stage may be varied as required for different classes of work. The operating efliciency of the tool is furthe increased by the provision of automatic means for periodically reversing the direction of rotation In the present instance, this is ac-- of the tool. complished by a reversal of the ,motor which drives the tool. Reversal of the tool tends 'to prevent loading" of the abrasive stones and equalizes wear over the entire surface thereof. .More over, when tool rotation is reversed, a different area of the abrasive stone is presented to the work, thus further increasing-the cutting efficiency of the tool. I

Control ofv the machine is effected through the medium of push'button' switches which may be grouped at a conveniently located central control station. The work of the attendant running the machine is thus materially simplified which fa- I cilitates eflicient operation.

General machine structure The machine illustrated in Fig. l 'of the draw-, ings comprises generally a carriage or head} mounted on a suitable frame (not shown) for reciprocation toward and from a stationary work supporting fixture I which holds the work piece 5 to be operated on. Reciprocation of the head is effected by means of a piston 6 operatively connected with the head by a piston rod 1. The piston is operable in a cylinder 8 mounted on the frame of the machine with its axis substantially parallel to the reciprocatory path of the head.

' A high pressure pump 9 driven by an electric motor it supplies pressure fluid to the cylinder .8 through a hydraulic circuit to .be described indetail hereinafter.

Journaled in the head 3 and reciprocable therewith is a hollow spindle ,H which carries on its projecting end a cylindrical honing tool l2 of well known construction. The spindle i l is arranged to be driven by a reversible motor I! mounted on the frame of the machine. In the machine illustrated, a rotary hydraulic motor is employed, although it will be understood that an electric motor may be used if desired.

The driving connection between the motor i 3 and the spindle-ll includes a gear ll rigid withthe spindle-which meshes with a pinion l5 fast on a drive shaft I6 adaptedto reciprocate with the head. The shaft It has a splined driving connection with a beveled gear I! journaled on the frame of the machine, which gear meshes with a beveled gear l0 on the shaft of the motor l3. Pressure fluid'for operating the motor I; is

- organizations.

able the tool to continue to operate at maximum supplied by a low pressure pump [9 driven by the electric motor In. v

The honing tool I2 is preferably of the general type disclosed in the copending application of A. M; Johnson, Serial No. 174,955. It comprises generally a plurality of abrasive elements arranged in a circular series in a cylindrical frame for. radial movement into and out of engagement with the surface of the work. For dressing internal cylindrical surfaces, the abrasive elements are arranged to face outwardly, their positions being reversed for honing external cylindrical.

surfaces. With either type of tool, movement of the abrasive elements into engagement with the I spindle II, the rod "projects into the axial bore of the-spindle for engagement by a push rod 2| operatively connected with a piston 22 workin in a'cylinder .23 in the head 3. Movement of the. piston 22 toward the lower end of the cylinder is effective to shift the rod 20 axially of the tool, the rod operating through the medium of suitable cams to positively expand the tool. Movement of the piston 22 in the opposite direction withdraws the push rod from engagement with the 7 rod 20 and permits contraction of the tool by the usual spring-contracting mechanism.

Hydraulic circuits and apparatus.

The hydraulic system of the machine illustrated may be considered as comprising three separate but intimately related hydraulic circuit One circuit is concerned with the reciprocation of the tool, the second with the rotation of the tool and the third with the actuation, that is, the expansion and contraction of the. tool. Pressure fluid is supplied to the circults by the high pressure pump 9 and the low pressure pump I9, both pumps drawing fluid from a common reservoir or sump 26 to which it is returned after use. Each circuit includes suitable valves which may be of the usual and well known construction for controlling the supply of pressure fluid to the cylinder 8, the hydraulic motor l3 and the cylinder 23, respectively.

The hydraulic circuit for reciprocating the tool includes a reversing valve 21 operated under control of a pilot valve 28 to direct pressure fluid into opposite ends-of the cylinder 8 alternately. Pressure fluid issupplied to the reversing valve by the pump 9 thrcughpressure ducts 29 and 30 and an"on-and-off valve if when the latter valve is'in its on position. The valve 3| is interposed between the pressure ducts 29 and 30 and effective in its off" position to shut off the latter ductand connect the pressure duct 29 with a drain duct 32 which returns the pressure fluid to the sump 26; As herein shown, the I valve 3| is biased to the "off" position and a solenoid VSI is provided for operating it to the on position.

The reversing valve 21 has a valve plunger 34.

shiftable between two positions in well known manner under control of the pilot valve 28. u

When the valve plunger is moved to the left, the upper end-of the pressure duct is closed and pressure fluid is directed through a duct to the lower end of the cylinder a. The piston' B is accordingly moved toward the upper end of the cylinder and spent pressure fluid is ex-' hausted therefrom through a duct 36, valve 21 and the drain duct 32.

When the valve plunger 34 is shifted to its alternate position, as shown in the drawings, the pressure duct 30 is connected with the duct 36 leading to the upper end of the cylindr 8. The lower end of the cylinder remains connected to the pressure fluid source but due to the greater efifective area presented by the upper end oi the piston 6, the force exerted on the upper end exceeds that on the lower end and the piston is accordingly moved downwardly. Pressure fluid exhausted'from the lower end of the cylinder is returned to the pressure system, thereby reducing the volume required to be delivered by the pump 9. A check valve Bl interposed in the duct 35 serves to equalize the weight of the reciprocating' parts. 4

The pilot valve th is actuated at each end of 'the tool stroke by suitable mechanical control means to be described hereinafter. The arrangementis such that once the machine is started reciprocation of the tool proceeds as long as the valve 3l\is held in on position by its operating solenoid VSl.

It has been found that a periodic. reversal of s the direction of rotation of the tool tends to precreases their useful life.

direction of rotation of the motor drive shaft in addition to an on-and-oif valve 39 for starting and stopping the motor. Pressure is supplied to this circuit by the low pressure pump l9 through a pressure duct 40. The valve 39 which is connected in this duct between the pump and the reversing valve is biased to the ofi position in which it shuts oif the supply of pressure fluid from the motor I3 and returns the fluid to the sump by way of the drain duct 32. A sole- -noid VS2 operatively associated with the valve 39 is effective when energized to operate the valve to the on position and thus initiate operation of the motor l3.'

.The direction in which the motor I3 turns and consequently the direction of rotation of the tool I2, is dependent upon the position of the reversing valve 38. The valve has a plunger 42 actuated by solenoids VS3 and VSI. Solenoid VS3 when energized shifts the valve plunger to one" end of the valve casing, thereby connecting the pressure duct M with aduct 45 which delivers the fluid to the motor in a manner such that the tool i2 is rotated in a clockwise direction. Spent pressure fluid from the motor is returned to the sump through aduct.. 16, mahre 3B and the'drai'nj'duct 32.

Solenoid V S4 whenenergized shifts the valve plunger 42 to the opposite end of the valve casing, thereby connectingthe pressure-duct with duct to reverse the flow of pressure fluid through the motor i 3. The direction of rotation of the motor is accordingly reversed and the tool I2 is rotated in a counterclockwise direction. Spent fluid pressure from the motor is,

returned to the sump by way of the duct 45, valve 38 and the drain duct 32.

For the reasons pointed out above, it is desirable to carry out the honing operation in different steps or stages such as rough honing and finish honing, in which tool pressure is adjusted to provide maximum cutting action without danger of injury to the tool or work. The hydraulic circuit for-expanding and contracting the tool I2 is therefore arranged with a particular view of providing an effective control of the pressure exerted by the tool on the work piece in the different stages of the operation. In the particular embodiment of the invention herein disclosed, a relatively light tool pressure is applied at the beginning of the honing operation and continued until the major irregularities of the surface have been removed. The tool pressure is then increased substantially to enable the tool to operate with maxim emciency.

The improved method increases the operating efliciency of the machine since it permits 'the rough work to be honed in a single operation. It is also advantageous in that it reduces to a minimum the strains imposed on the tool and work and materially increases the useful life of the tool.

In the illustrative embodiment of the machine, the means for controlling the pressure exerted Eli by the tool on the work is in the form of a valve so ll. which, as herein shown, is arranged for operation by a solenoid VSii. When separate sources of pressure fluid are available, the valve t? may be utilized to connect either source to the hydraulic circuit of the tool-actuating means selectively. In case only one source of pressure fluid is available, the valve fl'i may take the form of a pressure reducing or by-pass valve of any suitable'construction. Moreover, the valve l'l may be constructed for operation with more than two sources of pressure fluid or a plurality of such valves may be used to provide for actuating the tool in a greater number. of steps if desired. V

Referring to the drawings the valve ll as herein shown is a two-position valve spring biased to a position effective to connect. a duct 58 leading from the low pressure pump l9with a duct 5! extending to a reversing valve 52. The valve noid V56 andJs adapted to control the supply of pressure fluid to the cylinder 2 3-for expanding and contracting the honing tool l2. The valve is spring biased to a position in which it is eifective to direct the pressure fluid receited-via the duct 5| through a duct Stand a telescoping ex tensible connection 56 to the lower end of the cylinder 23, thus moving the piston 22 toward the upper end of the cylinder to contract the honing tool. Spent pressure fluid is exhausted from the upper endof the cylinder through a telescoping extensible connection 56, a duct 51, valve 52 and a branch 58 or the drain duct 32.

hydraulic circuit connections to the cylinder 23 thereby introducing pressure fluid into the upper end of the cylinder and exhausting thepressure fluid from the-lowerend of" the cylinder. The 75 4 Energization ofthe solenoid VSS reverses the piston 22 is thereby moved toward the lower end of the cylinder to expand the honing tool II.

in its normal unoperated position and solenoid- VS6 is energized, pressure fluid from the low pressure pump l6 will be supplied to the cylinder 23 to expand the tool with relatively light pressure. When the valve 41 is operated by the energization of the solenoid V86, pressure fluid from ths high pressure pump 9 is supplied to the cylinder 23 and the pressure'exerted on the work piece by the tool is correspondingly increased. Upon deenergization of the solenoid VS6, pressure fluid is introduced into the lower end of the cylinder 23 thereby contracting the tool, the speed of operation depending upon the position of the valve 41.. 1

' Mechanical controls The mechanical controls for governing the op-. erating cycle of the machine may be generally similar to those disclosed in the application of A. M. Johnson above referred to. They include generally a control rod 6 I supported on the frame of the machine for limited rotational and endwise movements. The latter movements of the control rod are utilized to operate the pilot valve 26 through the medium of an arm 62 fast on the rod which cooperates with an operating member 63 forming a part of the valve. These endwise movements are impartedto the control rod by a stop-engaging arm 64 carried on and reciprocable with the head 3. The arm 64 is positioned to engage adjustable stops carried by the control rod incident to the reciprocation of the head. Ordinarily, three stops are provided,

namely, an upper limitstop 65, a lower limit stop 66 and an intermediate stop 6'1. Stops 66 and 61 define the limits of the working stroke of the tool and are accordingly set for engage-J work. The advance of the head thus continues until the arm 64 engages the stop 66 thereby shifting the control rod and reversing thedirection of movement of the head. Upon the return movement the-arm 64 engages the intermediate stop 6!- and in this case is effective to shift the control rod and again operate the pilot valve to reverse the direction of movement of the tool. Thus, after the tool is inserted in the work, reciprocation through the working stroke is controlled automatically by the pilot valve and associated control mechanism.

To effect withdrawal of the tool from the work, the control rod 6| is rotated suillciently to move theintermediate stop 61 out of the path of the arm 64. Rotation of the rod may be effected either manually by means of ahandle 66 or automatically by a pull-out solenoid PSI. The solenoid PSI has an armature 66 operatively connected with a lever 10 having a slidable, nonrotatable-connection with the control rod. Thus, when the solenoid is energized, the rod is rotated sufficiently to move the intermediate stop 61 out of the path of the arm 64. The movement of the head therefore continues until the arm 64 engages the limit stop 66 and shifts the control rod to operate the pilot valve 26.

Means is provided for interrupting the operation of the machine automatically as an incident to the withdrawal of the tool fromthe work. As herein shown, this means comprises a limit switch LSI adapted to be opened by an operating member ll carried by the head 6. The parts are so positioned that the member engages the switch to open the same immediately following the operation of the pilot valve and before the return movement of the head is started. Thus, the pilot valve is set so that the next operating cycle will begin with an advancing movement of the head. The opening of the switch LSI interrupts certain of the control circuits to be described in more detail hereinafter.

Automatic means is also provided for initiatin! operation of the tool-actuating means to:- expand and contract the tool in proper timed relation to its insertion in or withdrawal from the work.

This control is effected through the medium of acontrol switch CSI incorporated in the electrical system of the machine so as to control the energization ofthe reversing valve solenoid V86 that when the tool has been advanced substantially entirely into the work, the member ll en: gages cam 14 to rock the shaft in a direction effective to close the switch CSI. With the shaft in this position, the cam 16 is moved into the path of the member II. However, this cam is positioned slightly above the uppermost point reached by the member II in the working stroke of the tool so that the cam is engaged only when the tool is being withdrawn from the work.

Upon such engagement, switch CSI is opened and the tool is contracted, thus avoiding any possibility of injuring the tool or work piece by attempting'to withdraw the tool while in expanded condition.

" Electrical controls The electrical control system comprises a series of electrically related circuits including relays, automatic control devices and manually operable switches for controlling the various functions of the. machine. The control is effected through the medium of valve operating solenoids VSi- -VS6 and the control rod operating solenoid PSI hereinbefore described.

Current for operating the relays and solenoids may be supplied from any suitable source. -In the preferred embodiment disclosed, the current for this purpose is obtained from a three-wire power line comprising line conductors Ll, LI

high voltage type and the circuits are arranged 7 the switch R|3 of the relay RI. 55

to connect them across the outside line conductors Li and L3.

The operation of the improved control system will be most readily understood when considered in connection with the operation of the machine. Assuming that the machine is in its normal idle condition, as shown in. Fig. l, and that the pump motor Ill is running, an operating cycle may be initiated by a momentry actuation of a normally open manually operable start switch Si (Fig. 2). This switch closes a circuit for a relay Ri. The relay upon energizing closes switches RH, Hi2 and RM, the second mentioned switch completing a circuit for the solenoid VSII which accordingly operates the valve M to on position. Pressure fluid is thus supplied to the upper end of the cylinder 8 to move thetool toward the work. As an incident to such movement, the limit switch LSl is closed, thereby completing a sealing circuit for the relay Rt by way of the relay switch RI i, a normally closed jog switch SZ anda normally closed stop switch S3. The solenoid circuit is therefore maintained closed and valve 3! is held in the on position until the relay is deenergized by opening the switch S3 or the limit switch LSi. Accordingly, the tool is reciprocated through the working stroke under control of the pilot valve 28 in the manner hereinbefore described,

When it is necessary to reciprocate the tool'or to advance it toward the work without initiating release of the switch the valve will return to off position to stop the machine.

Rotation of the tool is initiated by the momentary actuation of a normally open "start switch S4 which completes a circuit for a relay R2 having normally open switches R21 and-R22. The relay vclo es a sealing circuit for itself by way of the switch R2! and a normally closed 'stopf switch S5. Switch R22 completes a circuit for the valve operating solenoid VS2 which operates the valve 39 to on position to supply pressure fluid to the spindle motor l3, as previously explained- It will be observed that the initial energizing circuit as well as the sealing circuit for the relay R2 includes Thus the relay R2 can be energized only when the relay RI is likewise energized. In other words, rotation of the tool a stationary.

After-initiation of an operating cycle in the above manner, expansion of the tool I2 is effected automatically as an incident to its being fully inserted into the work. The initial expansion at low pressure is brought about by the closure of the control switch CSI which completes a circuit for a relay R3. The relay closes its switch R3I to energize'the solenoid V86 and thereby operate the valve 52 to direct pressurefluid into the upper end of the tool-expanding cylinder 23. Since valve 41 is unoperated atthis time, pressure fluid will be supplied to the cylinder from the low pressure pump l9.

inder.

Controlswitch CSl, in addition to closing the circuit for the relay It3, also completes a circuit for initiating the ope ation of a timing device or timer TMl. The timer may be of any suitable type and as herein shown comprises a suitable motor operated by the current supplied over the circuit closed by switch 05!. Switch-actuating mechanism of well known construction driven by the motor is arranged to close a normally open switch TMIZ after the lapse of a-predetermined time interval. The timer is preferably adjustable so that the interval required to close the switch may be varied as required.

Closure of the switch TMI2 completes a circuit for energizing the solenoid VS5 which operates the valve 41 to 'cut-ofi the supply of pressure fluid from the low pressure pump l9 and to connect the high pressure pump 9 to the tool-expanding cyl- Thus the pressure exerted by the tool is increasedto enable the tool to operate with maximum efilciency throughout the remainder of the operating cycle. The expansion of the tool in the manner above described has been found to be particularly advantageous in honing work pieces having a relatively'rough surface such as that left after a boring operation. The length of the light honing operation may be adjusted so that "the major surface irregularities are removed before high pressure is applied to the work by the tool.

Thus, the machine is enabled to carry out the improved honing method with a minimum of supervision or attention from the attendant. i

The timer switch TMI2 may also be utilized to initiate the operation of a control device such as a stroke counter or timer forterminating the operating cycle of the machine at the proper time. In the particular embodiment illustrated, the control device comprises a timer TMZ-which may be similar to the timer TM] above described. The time: has a normally open switch TMZI adapted to be preset manually in well known manner, to close a predetermined time after the timer motor is started. Closure of the switch TM2I completes a circuit for a relay R4 having a normally open switch RM and a normally closed switch R42. The switch RM when closed completes a circuit for the pull-out solenoid- PSI which, as previously explained, operates the control rod 6| to move the intermediate stop 61 out of the path of the stopengaging arm of the head. The head is accordinglymoved to its extreme limit position thereby withdrawing the tool from the work and eventually stopping-the machine by opening the limit switch LSI.

The switch R42 of the relay R4 is included in the circuit for energizing the tool-expanding relay R3. Accordingly, the opening of this switch is eifective to deenergize the relay R3 and thereby interrupt the circuit of the valve solenoid VSB. The valve solenoid immediately releases the valve 52 for return to normal position whereby pressure fluid is directedinto the lower end of the cylinder 23 to Since release of the valve takes contract the tool. place during a'working stroke of thetool, the valve control switch CSI will be in closed position and.

the valve solenoid VSS will be energized so that pressure fluid from the high pressure pump 9 will be supplied to the cylinder 23. The tool will or work by attempted withdrawal while the tool is expanded is eflectually avoided.

Upon withdrawal of the tool, the switch 08! is opened incident tothe engagement of the operating member II with the cam 15 of the switch operating mechanism, thereby opening the circuit of the valve solenoid VS5 to restore the valve 41 to normal position.

Means is provided by which the. working stroke portion of the operating cycle may be increased or decreased, as desired, independently of the timer TM2. As herein shown, this means comprises an increase switch of the normally closed manually operable type interposed in the circuit of the relay R4 in series with the timer switch v'IM2l and a normally open decrease switch 81 arranged to close the circuit of the relay R4 independently of the timer switch' TMZI. Thus, when the switch S6 is actuated; closure of -the timer switch is ineffective to energize the relay R4, and accordingly reciprocation'of the tool through its working stroke continues as long as the switch is held in open position. Upon re-' lease of the switch, a circuit for the relay is completed through the timer switch and the operation of the machine is interrupted in the usual manner. Operation of the switch S1 at any time is effective to energize the relay R4 and immediately stop the machine;

A relay R5 is provided for closing the circuits of the valve operating solenoids VS3 and VS4 selectively. As explained hereinbefore, these solenoids when energized operate the reversing valve 38 to control the direction'of rotation of the honing tool l2. As herein shown, the relay R5 is provided with two. normally open switches R5| and R52 and a normally closed switch R53.

The latter switch is connected in the circuit of the valve solenoid VS 4 so that when the relay R5 is in its normal deenergized condition solenoid VS4 is energized-and the valve 38 is set to effect rotation of the tool in one direction. The switch V R53 is connected in the circuit of the solenoid VS4. Upon energization of the relay R5, solenoid' VS3 is energized and solenoid VS4 is deenergized, the valve 38 being operated to the reverse position to efiect rotation of the tool in the opposite direction.

Energization of the relay R5 may be controlled either manually or automatically. To this end,

i two separate circuits are provided for the relay.

' shown in the drawings the relay is energized upon ating circuit for the timer.

These circuits are arranged to be connected up selectively by a manually operable switch S8. With the switch S8 operated to the position actuation of a normally open switch S9 and is maintainedenergized over a sealing circuit in cluding the relay switch R5I and manually operable normally'closed stop switch Sill- Operation of the latter switch is effective to interrupt the circuit of the' relay and thus bring about a reversal in the direction of rotation of the tool.

The switch S8 when operated to its alternate position connects up the second circuit for the relay R5 which circuit is arranged to be closed and opened periodically by a motor-operated timer TM3 through the medium of a switch 'I'M3I. The timermay be ofany suitable construction and as herein shown is equipped with a suitable cam 16 whichalternately closes and opens the switch TM3I to energize and deenergize the relay R5." The switch SH, closed simultaneously with the operation of the switch S8 to its. alternate position, completes the oper- During the, honing operation, coolant is supplied to the tool by a suitable pump driven by an electric motor 11. The motor is started by the jog switch S2.

, rotation of the. tool.

momentary actuation of a normally open switch 8 which completes a circuit for a relay R6. Relay R6 closes switches R61 and R82 thereby completing a sealing circuit for itself and a circuit for a motor switch solenoid MSI. The sealing circuit for the relay includes a normally closed stop switch Slleflective when actuated to open the circuit of the relay and thus stop the pump motor. Solenoid MSI when energized closes a switch MS|2 to connect the motor ll across the power line.

Brief rsum of operation TM2 are adjusted or set to provide the desired operating intervals for' low and high pressure operation. The switch S8 is also operated to connectup either the manual or automatic control devices for controlling a direction of rotation of the tool. The coolant pump motor 11 is started by momentary closure of the start switch Sl2.

The operating cycle of the machine is now initiated by momentary closure of the startQ switches SI and S4, energizing the relays RI and R2, respectively, to start reciprocation and Switch SI is, held closed until the tool head moves away from its limit position sufliciently to close the limit switch LSI. The operation oi. the machine is then continued independently of the starting switch due to the relays RI and R2 being maintained in energized condition over self-closed sealing circuits.

The tool is advanced into the work in a collapsed condition, and when fully inserted in the work is expanded incident to the closure of the control switch CSI which completes a circuit for the relay R3 and the timer TMI. Relay R3 completesa circuit for the valve solenoid VSS and the solenoid operates the valve 52 to toolexpanding position. Pressure fluid from the low pressure'pump I9 is accordingly-supplied to the upper end of the tool-expanding cylinder 22 and the tool is expanded with relatively light pres-' sure. Reciproca'tion of the tool through the working stroke continues with the tool thus expanded until the timer TMI closes the switch Closure of the latter switch completes a circuit for the solenoid VS5and a circuit for the timer TM2. Solenoid V35 shifts the 'valve 41 to direct pressure fluid from the high pressure pump into the tool-expanding cylinder, thus materially increasing the pressure exerted tool on the work.

Reciprocation of the tool through the workby the ing stroke continues until the timer TM2 closes the switch TM2I to energize the relay R4. En-

ergization of this relay brings about the energization of the pulhout solenoid PSI and the deenergization of the relay R3. Solenoid PSI rocks the control rod Bl to move the .intermediate stop 5'! out of the path of the arm so that in the next return stroke the tool head will move to its extreme limit position and open aromas 7 the limit switch LSl. Deenergization of relay Rt interrupts the circuit of the solenoid V86 which releases the valve 52, thereby directing the pres-- instead of automatically, if desired, by operation I of the switches S8, S9 and Sill.

The movement of the head to its limit position withdraws the tool from the work, operates m the pilot valve to its alternate position and opens Opening of the limit the control switch CSl. switch LSI stops the machine by opening the circult of the relay Rl, which relay in turn opens the circuit of the relay R2. These relays, as m above explained, control reciprocation and rotation of the tool respectively. With the switch CS1 open, solenoid VSE is deenergized and valve 47 is returned to normal position. Likewise, with the pilot valve 23 operated to its alternate posilo tion, reversing valve 2! is set to direct pressure fluid into the upper end of the cylinder ll. Thus the machine is conditioned for the next operating cycle.

It will be apparent from the foregoing that the a invention provides a new and improved method of honing cylindrical surfaces together with a honing machine of novel and advantageous constructionparticularlyadapted to carry out the improved method. The machine embodies suitable means by which the direction of rotation of the tool may be reversed either manually or automatically at predetermined intervals, to enable the tool to operate withmaximum elficiency. The machine likewise embodies novel means by which 5 the tool may be actuated in steps to'exert different degrees of pressure upon the work piece in different stages ofthe honing operation.

The invention also provides a control system of novel character which materially simpli- 50 fies the work of the attendant in controlling the operation of the machine. The various machine elements are under complete control of the operator at all times and capable of being started and stopped by simple actuation of push button 'con- 5 trol switches, The control system includes automatic devices by which the different stages of the working stroke cycle may be controlled without the intervention of the attendant. It likewise includes novel means for terminating the oper- 1 ,q, ating cycle of the machine subject to. instant change by the attendant whenever necessary.

We claim as our invention;

' 1. In a machine for-honing cylindrical SUI?- racesjin combination, a honing; tool havinga plul 5 rallty ofabrasive' elements arrangedin a circularseries, tool-actuating means operative to shift said elements radially to force the elements into engagement with, the surface of a cylindrical work piece. a support for said tool,,a sup- 70 port for the work piece, means for reciprocating 'port to cause the tool to-operate on the surface of the'work piece, means for rotating one of saidsupports' during said reciprocation to efgmfect relative rotation of the tool and work, hy-

"and contractible tool, hydraulically-actuated tool-actuating means to force the abrasive ele merits of the tool against the work. piece, a first and a second source of pressure fluid, the fluid supplied from said second source being at a g higher pressure-than the fluid supplied from said first source, a valve operable to connect either of said sources to said hydraulicallyoperated means selectively, and a timing device for operating said valve.

2. In a machine for honing cylindrical surfaces, in combination, a honing tool having a plurality of abrasive elements arranged in a circular series, tool-actuating means operative to shift said elements radially to force the elements into my engagement with the surface of a cylindrical work piece, a support for said tool, a support for the work piece, means for reciprocating one of said supports relative to the other support to cause the tool to operate on the surface of the w workpiece, means for rotating one of said supports during said reciprocation to eilect relative rotation of the tool and. work, hydraulicallyopenated means for operating said tool-actuating means to force the abrasive elements of the tool g5 against the work piece,a first anda second source of pressure fluid, the fluid supplied from said second source being at a higher pressure than the fluid supplied from said first source, and means for connecting either of said sources to said my hydraulically-operated means selectively.

3.-In a honing machine, in combination, an

' expansible and contraotible honing tool, means for supporting work to be operated on by the tool, means for effecting relative rotation and reciprocation of the tool and work, hydraulicallyactuated means including a cylinder and piston mechanism for expanding and contracting the tool, a low pressure fluid source and a high pressure fluid source, a valve normally effective to supply. pressure fluid from said low pressure source to said hydraulically-actuated means, means for operating said valve to supply pressure fluid from said high pressure source to said hydraulically-actuated means. a second valve operable to direct pressure fluid into opposite ends of said cylinder alternately to expand and contract the tool, and means for operating said valves.

4. In a'honing machine, in combination. an'

expansible and contractible honing tool, hydrau- Really-actuated means for expanding and co'ntracting the tool to engage and disengage the surfaceof the work being operated on, means for effecting relative rotationand reciprocation of 5 the tool and work, a source of high pressure fluid, a source oflow pressure fluid, a valve normally effective to connect said low pressure source to= said hydraulically-actuated means to expand the. tool, and meansfor' operating'said valve to connect said high pressure source to'sald hydrau-P lically actuated means whereby to increase the pressureexerted by'the tool on thework. 7 5. In a machine for dressing cylindrical surlaces by rough and finish honing operations, means for rubbing a plurality or abrasive elements over the surface -with a combined rotary and reciprocatory motion, means for forcing the elements'against thesurface with a d fferent pressure in each or said operations, anda sepa-' 7o one of said supports relative to the other sup ratejtiming device for terminating each operation.

6; Ina machine for honing cylindrical ysurfaces in combination, a cylindrical expansible means for expanding and contracting the tool, power-driven means for effecting relative rotation and reciprocation of the tool and the surface being operated on, a first timing device operative. to control said hydraulically-actuated means, and a second timing device operative 'to control said power-driven means.

7. In a honing machine, in combination, an expansible and contractible honing tool, hydraulically-actuated means for expanding and contracting the tool to engage and disengage the surface of the work being operated on, means 'and contractible honing tool, means for supporting a work piece to beoperated on by said tool, means for moving the tool into the work piece while the tool is contracted, means for expanding the tool to exert a predetermined pressure upon the work piece, means for rotating and reciprocating the tool in the workpiece to dress the surface thereof, a timing device initiated in operation upon the expansion of said tool, and means controlled by said timing device for increasing the pressure exerted by the'tool on the work piece.

9. In a machine 'for honing cylindrical surfaces, in combination, an expansible and contractible honing tool, means for supporting work to be operated on by said tool, means for effecting relative rotation and reciprocation of the tool and work, power-actuated means for expanding the tool into engagement with the surface of the work, means operative to increase the pressure exerted by the toolon the work, a timing device for controlling the operation of said pressure increasing means, a second timing device, and means controlled by said second device for interrupting the relative rotation and reciprocation of the tool and work.

10. In a machine for honing cylindrical surfaces, in combination, an expansible and con-' tractible honing tool, means for supporting a work piece to be operated on by said'tool, means for moving the tool into operative relation to the work piece while the tool is contracted, means for expanding the tool to exert a predetermined pressure upon the work piece, means for rotating and reciprocating the tool relative to the work piece to dress the surface thereof, a flrst timing device and a second timing device, means controlled by said first timing device for increasing the pressure exerted by the toolon the work piece, and means controlled by said second timing device for contracting the tool and for effecting withdrawal of the tool from the work.

1. Ina honing machine, in combination, a-

and means controlled by said device for reversing the direction of rotation of said support.

'.12. In a honing machine, in combination, a support for a honing tool, a support for work to be operated on by said tool, power-actuated means for reciprocating one support relative to the other support, power-actuated means for rotating one of said supports, power-actuated means for expanding and contracting the tool, electrical control means for said power-actuated means, circuits for the electrical control means of said flrst and second power-actuated means, manually operable switches for opening and closing said circuits to start and stop rotation and reciprocation of said supports, a circuit for the control means of said third power-actuated means, and a switch for opening and closing said last circuit operable by the reciprocating support. 13. In a honing machine, in combination; a honing tool having a plurality of abrasive elements arranged in circular series, tool-actuating mechanism operative to shift the abrasive elements radially to force them into operative engagement with the surface of a cylindrical work piece, a support for the tool, a support for thework piece, means for reciprocating one of said supports relative to the other support to traverse the tool axially of the work piece, means for rotating one of said supports during said reciprocation to effect relative rotation of the tool and work, pressure fluid means for operating said tool-actuating mechanism to. force the abrasive elements of the tool against the surface of the work piece, a valve controlling the supply of pressure fluid to said pressure fluid means to vary the pressure exerted by the abrasive elements on the work piece, and means for operating said valve to cause the tool to exert a relatively light pressure in the initial stage of the honing operation and a substantially higher pressure at a succeeding stage of the honing operation.

14. In a honing machine, in combination, a honing tool having a plurality of abrasive elements arranged in circular series, tool-actuating mechanism operative to shift the abrasive ele- .ments radially to force them into operative engagement with the surface of a cylindrical work piece, a support for the tool, a support for the work piece, means for reciprocating one of said supports relative to the other support to traverse the tool axially of the work piece, means for rotating oneof said supports during said reciprocation to effect relative rotation of the tool and work, pressure fluid means for operating said tool-actuating mechanism to force the abrasive elements of the tool against thesurf-ace of the work piece, a valve for controlling the pressure of the fluid supplied to said'fluid operated means and operable to vary the pressure exerted by the abrasive elements on the work pieceaand means for automatically operating said valve during the honing operation. 1 1

a 15. In a honing machine, in combination, an expansible abrasive tool, means for supporting work to be operated on by said tool; means for effecting relative rotation of the tool and work, means for effecting relative reciprocation of-the tool and work through a definite working cycle,

, power-actuated means for expanding the tool to exert a predetermined pressure on the work upon initiation of said working cycle,-and means operable automaticallya predetermined time after the initiation of the working cycle for modifying the action of said power-actuated means-to change the pressureexerted by the tool on the work.

v 16. A'method of .honing cylindrical work-to exact dimensions and with a true contour and smooth surface flnish which comprises effect- ;ng relative rotation and reciprocation of an expansible abrasive tool and the work for a ,deflnite interval, expanding the tool against the surface of the work with a relatively light pressure during an initial portion or said interval suflicient to remove the major surface irregularities from the work, and substantially increasing the pressure of the tool against the work for the remainder of the interval, the increased pressure being such as to enable the tool to the work to the desired dimension.

17. In a honing machine, in combination, a honing tool, a support for said tool,'a support for work'to be operated on by said tool, means for eifecting relative reciprocation 01 said supports to traverse the tool over the surface of the work, power-actuated means for rotating one oi! said supports to'eifect .a relative rotation of the tool and work, and means automatically operativeat predetermined intervals for reversing the direction of rotation, of said one support without in-' .terrupting the'relati-ve reciprocation of the supports.

18. In a honing machine, in combination, a

support for a honing tool, a support for work to be operated on by the tool, power-actuated means for initially movingone support relative to the other support to operatively associate the tool and work and for'subsequently eflecting relative reciprocation or the supports through a working cycle in which the tool is repeatedly traversed over the work, power-actuated means for rotating on 0! said supports during the working cycle, control a mechanism for said power-actuated means including manually operable means eiiective to initiate the operation of the poweractuated means, means for continuing the operation of said power-actuated means independently of said manually operable means, an electrically driven timing device, means for automatically initating the operation of said device after the tool and work are brought into operative association, and means controlled by said device for stopping said power-actuated means to terminate the working 20 OYOIE.

. ALBERT M. JOHNSON.

WALTER M. FAIRBAIRN.

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