US2108354A - Blind end cylinder honing machine - Google Patents

Description

F b. 15, 1938. F, A. SWANSON 2 8,354 v BLIND END CYLINDER HONING MACHINE Filed June 8, 1955 2 Sheets-Sheet 1 NVENTOQJ QATTOIQIjEEjS Feb. 15, 1938. F, A. swANsoN BLIND END CYLINDER HONING MACHINE Filed June 8, 1935 2 Sheets-Sheet 2 NVENTOIQ/ Patented Feb. 15, 1938 PATENT -OFFlCE amass; nnmn nun crmvnna HONING moms Floyd A. Swanson,

Rockford, Ill., asslgnor to Barnes Drill (30., Rockford, 111., a corporation of Illinois Application June a, 1935, Serial No. 25,546 v This invention relates to an improved honing machine and in, particular to a machine of this character for finishing the interior walls of cy'linders having one end closed or obstructed. such.

and overruns the ends, as in an ordinary auto- 10 mobile engine block, the metal removing effect of the tool is uniform because at every stroke contact is had throughout the length of the tool identically with every part of the cylinder wall. When honing an obstructed or blind end cylinder, however, the stroking movement of the tool must be stopped short of the-obstructed end and in consequence the parts of the cylinder wall adjacent this end do not receive the benefit of treatment from the whole length of the tool as do the remaining parts of the wall. That is, the same amount of metal per unit area is not removed throughout the bore because the longitudinal movement ofthe grinding stones of the honing tool in contact with the inner end of the cylinder wall is necessarily restricted and the tool therelength of time with this part of the wall as with the'remaining parts. Correction of this condition by causing the tool to operate equally upon 30 every part of the cylinder wall is of great importance because of the requisite for uniformity in piston operated mechanisms such as airplane engines and the like. In a radial airplane engine the blind end of the cylinder is that which forms .35 the cylinder head, and the piston of such an engine must closely approach the head in order to develop the necessary compression for operation. It is clear, therefore, that in order to obtain proper results from the engine, and topre- 40 vent excessive wear on the piston, the cylinder wall .throughout'must be as nearly perfect in uniformity of diameter andfinishas possible.

An important object of the present invention, therefore, is to provide a blind end cylinderhoning machine embodying a reciprocating, rotary tool and having control means for the tool operative to compensate for the necessarily restricted stroking movement of the tool along the area adjacent the blind end of the bore so that 5 the metal removed per unit area from the bore wall will be substantially equal throughout.

Another object resides in the provision of an improved honing machine for finishing the bores of blind end cylinders including a work support and a tool support carrying a honing tool rofore is not in operative contact for the same tating at constant speed with means for imparting. rapid reciprocatory movements to one of said supports through a predetermined range and arranged to vary the rate of relative reciprocation at one end of said range. 5

Another object is to provide a honing machine in'which a honing tool rotated at a constant speed isarranged for reciprocation relative to a work piece having an obstructed or blind end cylindrical bore, thereby carrying the tool through a predetermined range overrunning the free end of the'bore and closely approaching the blind end, and having automatic control means for interrupting reciprocal movement of the tool for a predetermined interval while the same is near said blind end so that the tool will be in metalremoving contact with the cylinder wall adjacent this end for a substantially equal length of time as with the remainder of the wall.

Another object is to provide a honing tool of the foregoing character in which the automatic control means is adjustable through a substantial range to vary the period of delay in the reciprocal operating cycle and thus the length of time the honing tool will be in metal-removing contact with the wall of the cylinder adjacent the obstructed"- part thereof.

A more detailed object resides in the provision in a honing machine, embodying a hydraulically reciprocated honing tool, of a delayed action valve arranged in conjunction with the main control valve of the hydraulic circuitof the machine to delay the return movement of the reciprocal stroke of the tool, and manually adjustable to any one of a plurality of operative positions accurately determinative of the period of delay.

Another object resides in the provision. in a honing machine including a reciprocating rotary honing tool of improved adjustable positive depth stop means for preventing movement of the tool beyond a predetermined point short of the blind end of a cylindrical bore, and means for cushion? ing operation of the stop means so as to prevent jarring of the. machine.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, in which:

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

Fig. 2 is a schematic representation of the hydraulic operating means and the delayed action control means.-

Fig. 3 is an enlarged sectional view of the delayed action valve.

Fig. 4 is an enlarged fragmentary sectional view taken substantially along line 4-4 of Fig. 3.

Fig. 5 is an enlarged fragmental elevational view partially in section, of the tool-carrying spindle and the stop cross arm which is carried thereby.

The invention has been successfully embodied in a honing machine of the general type illustrated in Fig. 1, and adapted for honing to a substantially uniform, smooth and highly finished surface, the internal cylindrical walls of obstructed bores of the character employed in such machinery as certain compressors or of blind end cylinders such as encountered in radial aircraft motors and the like. The machine selected for purposes of illustration, is of the vertical type embodying a base l0 carrying .a column or standard l2, near the lower end of which is an adjustable work support 13 upon which the work piece to be honed may be mounted in the usual manner. Vertically supported from the upper end of the column I 2- is a stationary tool head indicated generally at l4 and supported on one side of the column overlying the work support I3. The means for performing the actual honing operation comprises in the present instance a single honing tool I5 of any preferred type carried upon the lower end of a rotatable spindle I! which is suitably journaled in the tool head l4 and reciprocated relative to the work support'l3 so as to move the honing tool into and out of the cylinder bore of the work piece.

In the preferred embodiment of the invention the honing tool is continuously rotated during the honing operation at a predetermined'constant speed, and to this end the spindle I1 is provided with a splined section l8 operatively associated with a beveled crown gear l9, mounted on a fixed axis within a gear housing 20, and forming part of a gear train (not shown) of well known type operated by an electrical motor 22. Suitable clutch mechanism (not shown) is supplied for controlling operation of the gear train, and means such as a manually operated lever 23 is mounted on one side of the column l2 and has a linkage connection 24 for actuating the clutch mechal'llSm.

In the present instance reciprocal motion is imparted to the tool spindle I! by hydraulic means including a cylinder 25 conveniently mounted upon the upper end of the tool head 14 and having therein a reciprocating piston 21 which is secured upon the upper end of the spindle. The piston 21 is caused to reciprocate by alternately introducing pressure fluid to opposite sides thereof, the means for accomplishing this being shown (Fig. 2) as including an upper pressure-fluid delivery line 28 connected with the 'upper end of the cylinder, 25 for delivering pressure fluid to cause downward motion of the piston 21, and a lower pressureefluid delivery line 29 connected with the lower end of the cylinder for delivering fluid to cause return movement of the piston.

Pressure fluid is delivered to the lines 28 and 29 through a feed line 30, one end of which is disposed for withdrawing the fluid from a reservoir 32. Asuitable pump 33 in the line 3!! creates the necessary fluid pressure.

and to this end a direction control valve 34 spective pressure fluid lines. This control valve The flow of pressurefiuid from the line 30 is controlled to pass only .to one of the delivery lines 28 or 29 at a time;

may be of the type embodying a cylinder carrying a reciprocal plunger 35 having a pair of spaced full diameter portions 31 and 38 movable relative to the outlet ports of the pressure fluid delivery lines 28 and 29, respectively, and so arranged that the line 30 discharges between the same in any position of the plunger. Thus, as the plunger 35 is reciprocated, the pressure fluid delivered by the line 30 will be alternately delivered to that delivery line of which the outlet is between the enlarged diameter portions 31 and 38. As the pressure fluid is delivered to one side of the piston 21 through one of the lines 28 and 29, the fluid on the opposite side of the piston is exhausted through the other line and passes through the control valve for return to the reservoir 32 through a return line 39.

In order to prevent the building up of excessive pressure in the cylinder 25 while the machine is inactive, a cut-out valve 40 is placed at a suitable point in the feed line 30 for diverting the stream of pressure fluid to the return conduit 39 in the periods between operations. Control of the cut-out valve 49 is effected through the operating lever 23 which may be connected thereto by suitable means such as a linkage system 4| so that the delivery of pressure for reciprocating the spindle I! will be coordinated with operation of the rotary drive clutch mechanism. Operation of the direction control valve 34 is effected automatically in the present instance through an auxiliary hydraulic circuit adapted to shift the plunger 35 coordinately with the attainment of upper and lower limits of the reciprocal range of the tool spindle H. In the present instance this auxiliary hydraulic circuit includes a line 42 connected with one end of the valve 34 and a line 43 connected with the other end of the valve, both of these lines having connection through a pilot valve 44 with a line 45 branching from the pressure fluid delivery line 30. The ends of the plunger 35 carry projecting pistons 41 and 48 fitting slidably in auxiliary cylinders 49 and 50, respectively, at the opposite ends of the valve casing. It will be seen, therefore, that as the pilot valve 44 completes a pressure fluid connection between either of the lines 42 or 43 and the branch line 45, pressure fluid will be delivered to the respective cylinder 49 or 50 to move the'plunger 35.

, Automatic operation of the pilot valve 44 is attained through the medium of means such as longitudinally movable and manually rotatable skip-stop'mechanism 5| connected with the pilot valve 44 and having an adjustable upper limit stop 52, an adjustable skip-stop 53 and a lower limit stop 54. A stroking arm 55 connected with the tool spindle is positioned to engage the stops at predetermined points in the reciprocal cycle. It will be seen, therefore, that as the spindle moves the arm 55 away from the stop 52 to approach the work the arm passes the skip-stop 53 and proceeds into the cylinder bore to the lowermost limit of the reciprocal cycle. Thereupon, the stop 54 is engaged to move the skip-stop mechanism and shift the pilot valve. Upward movementof the spindle is limited at a point short of withdrawing the tool entirely from the bore by engagement of the stroking arm with the stop 53 and reversal of the reciprocal cycle. Reciprocation of the spindle, through this arrangement, is continuous until the machine is halted by movement of the lever 23 :or otherwise. The length of the reciprocal stroke of the spindle and tool is accurately defined by the spacing By the present invention, uniformity of result in honing blind end cylinders is obtained by halting the honing tool positively at a predetermined point within the cylinder as close to the blind end thereof as possible; and by the provision of means for automatically causing a carefully calculated delay in the transition from the.

downward or approaching to the return reciprocal strokes of the tool. By thus increasing the duration of contact of the rotating tool with the effected part of the cylinder wall, enough metal is removed per unit area to compensate for any deficiency in thisfspect resulting fromthe necessarily restricted longitudinal movement of the tool in engagement with the wall. In Fig. 2 a blind end aircraft cylinder 51 is shown as the work piece being honed, and the hone I5 is in the limit position most closely approaching the blind end where compensating metal removal is effected.

Insertion of the honing tool is accurately limited at a given point near the blind end of the cylinder bore through cooperatively arranged means on the stationary tool head 14 and the spindle II. To this endabutment shoulders 58 'on the tool head are arranged on opposite sides.

of the spindle axis, and a cross arm 59 for engagement with the shoulders is attached rigidly to the spindle at a point on its length which will cause the same to be halted positively at the predetermined extreme limit of the downward stroke of the spindle. As best seen in Fig. 5,

the spindle l1 may be in two sections, having its upper section'coacting rigidly with the cross arm and having the lower section coupled for relative rotary movement. In a preferred construction. the upper end of the lower section of the spindle may carry a fixedly pinned flange l'l which is .interposed between suitable antifriction means such as bearings 11 The bearings may be supported within a housing 59 bolted securely to the lower side of the cross arm 59. In. this manner the entire spindle may be reciprocated freely but only the lower section thereof which carries the honing tool need be rotated:

Preferably the cross arm 59 has a pair of similar portions extending to opposite sides of the spindle and extending through slots 60 in the tool head. The cross arm may be adjustable bodily relative to the spindle,-and is shown as having adjustable screw abutments 62 for minutely adjusting approach of the arm relative to the shoulders 58 to effect minor variations in stroke length. Desirably, the stroking arm 55 may form an extension of one branch of the cross arm 59.

The means forcausing the tool l5.to dwell near an internal obstruction or at the blind end of the cylinder, forms part of the auxiliary hydraulic circuit which operates the control valve 34. As shown, it is arranged to delay shifting of the plunger 35 for initiating the flow of pressure fluid through the lower delivery line 29 and thereby delaying return movement of the piston 21. To this end the pressure fluid line 43 is arranged to permit an unrestricted flow of pressure fluid into the auxiliary cylinder 50 and toward the plunger 35in order to shift the latter promptly for initiating the down stroke of the tool spindle. Means is provided, however, for

restricting the return or exhausting flow of fluid when the pilot valve 44 is shifted to a position as seen in Fig. 2, after the completion of a down stroke of the spindle. To this end a unidirectional flow valve 63 is mounted in the line 43 for permitting flow therethrough only in one direction. An exhaust flow of pressure fluid is thus permitted only through a by-pass line 64 extending around, and having its ends connected to the line 43 on opposite sides of the unidirectional valve. In the by-pass line 64, is means permitting only a restricted exhausting fluid flow from the cylinder 50, thereby allowing only a defined slow movement of the'plunger 35 under the influence of full pressure through the line 42 on the auxiliary piston 41. Herein this means is shown as a delayed action valve 65.

Under varying circumstances the length of the period of dwell of the honing tool will have to be increased or shortened. For this purpose the delayed action valve 65 is arranged for adjustment to accommodate the necessary variation. Herein this is accomplished by providing the valve with a rotary stem 66 (Fig. 3) having in one end an axial bore 61 with which communicates a series of radial cylindrical orifices 68 of graduated diameters. The stem has a flange 69 on its inner end, and is journaled in a suitably bored housing 10 in which one end of the bore is enlarged to provide a chamber 12. The inner end of this chamber is fashioned to provide a shoulder 13 against which the flange 69 is in snug suificient to retain the valve stem in any adjusted position. The outer end of the stem 66 extends through a packing gland 11, and has a handle 18 by which thestem may be adjusted rotatably by simple manipulation.

The orifices 68 register one at a time with a port 19 which is bored transversely in the housing 10 and which provides means for threadedly receiving a fitting M by which, the remaining end of the by-pass line is connected to the housing. Thus, it will be seen that as the respective orifices 68 are brought into register with the port 19, the exhausting flow of fluid through the valve will be directly proportionate to the size of the active orifice. Thereby accurate control may be had over the length of time requiredfor comthe valve plunger 35 to shift. If desired, an imperforate segment 80 may be left between two of the orifices 68 so that the user may drill a suitable oriflce therein to provide for a given period of delayed action that may not have been contemplated at the time the machine was orig inally assembled.

In operation the motor 22 and the pump 33 are operated'continuously, and after the cylinder 51 of the work piece has been adjusted upon the work support l3, the operator by movement of the lever 23 sets into operation the mechanism for rotating the spindle. and closes the'cut-out valve 40. Pressure fluid is forced through the feed line 30 into the auxiliary line 43 to move the control valve plunger 35 to the ieft, as seen in Fig. 2, so as to expose the port; upper delivery line. 28, thus initiating the recipleading to the rocal cycle of the tool spindle l1. When the 75 stroking arm 55 engages the stop 5, it moves the stop mechanism 5| and shifts the pilot valve H to reverse the flow of pressure fluid through the auxiliary hydraulic systemtby effecting pressure fluid connection between the branch line and the line 42.

Preferably, the stop 54 is arranged to be engaged by the stroking arm a short time before the stop arm abutments 62 strike the shoulders 58, so that the enlarged diameter portions Hand 38 of the control valve plunger will begin to move across the ports leading td the delivery lines 28 and 29, before the downward movement of the honing tool is halted, and at a rate determined by the delayed action valve 65. In this manner pressure fluid exhausted through the. lower delivery line 29 and the delivery passage of fluid to the upper delivery line 28 will be cut-off by gradual degrees until 'the stop arm abutments strike the shoulders 58, thereby gradually bringing the spindle to a halt and cushioning the mechanism against concussion which would otherwise result between the shoulders and the stop abutments.

As the enlarged portions 31 and 38 of the control valve plunger move entirely across the ports of the delivery lines 28 and 29 as seen in Fig. 2, the flow of pressure fluid to or from the reciprocating cylinder 25 is entirely halted so that the honing tool l5 will remain in continuously r01 tating operative contact for a defined interval with the wall of the cylinder 51 near its blind end. By properly proportioning the duration of the dwell, therefore, the metal removed from the inner end of the cylinder wall during the dwell will compensate for that removed from the remaining portions of the cylinder wall during the full stroking movement of the tool in engagement therewith. As a result, diametrically opposite sides of the cylinder wall will be in substantially perfect parallelism throughout.

As soon as the plunger 35 has been moved sufficiently to open the port of the delivery line 29, the return stroke of the tool spindle will be initiated, and the return movement will continue until the stroking arm 55 strikes the stop 53. 'I'hereupon the pilot valve M will be shifted again, and the. reciprocal movement of the spindle reversed in a repetition of the operation just described. When the machine is to be stopped,

, the skip-stop 53 will be moved out of the path of the stroking arm and the honing tool will be carried away from the work piece a distance determined by engagement of the arm with the upper limit stop 52;

From the foregoing, it will be observed that the present invention provides an improved automatically operating honing machine for truing and finishing the bores of obstructed or blind end cylinders. The machine embodies a novel cooperative arrangement of positive stop and delayed action control mechanism for halting the honing tool at a predetermined point within the cylinder bore short of the blind or obstructed end and for retaining the same in rotary engagement at such point for a definite period calculated to compensate for the'restricted stroking action of the tool on the portion of the cylinder wall adjacent said end as compared with its action on the remainder of the walls Through this novel arrangement and relationship of parts and accurate adjustment of the control mechanism operation of the machine is so eifected that the honing tool will remove metal substantially equally per unit area uniformly throughout the cylinder bore.

By blind and cylinder is meant a cylindrical bore containing any obstruction which prevents movement of the honing tool entirely therethrough, such as a closure or flange at one end of the bore, a shoulder as encountered in integral concentric bores, or the like, the blind end being that partof the cylinder construction which causes restriction of the reciprocal stroke of the tool.

I claim as my invention:

1. A honing machine for truing the bores of blind ,end cylinders of internal combustion engines or the like, comprising, in combination, means for supporting a work piece having a blind end cylinder to be honed, a honing tool, operating means including a rotary and reciprocatory tool spindle supporting said-honing tool in position for insertion into said cylinder, actuating means for imparting reciprocal motion to said spindle, means for rotating said spindle continuously while the tool is in the cylinder, means for operating said actuating means including a hydraulic system embodying a pilot valve, means for controlling said pilot valve including reciprocal cycle defining stop mechanism operable as an incident to the attainment of opposite reciprocal limits by said tool spindle, limiting means for positively halting insertion of said tool into the work beyond a predetermined point short of the blind end of the cylinder, a member engageable with and serving to move said stop mechanism and operate said pilot valve commencing at a predetermined point prior to halting of the tool by said limiting means, and means in said hydraulic system including an adjustable delayed action valve for delaying operatiomof sage: system and thereby of said actuating means a r said limiting means has haltedinsertion of the tool, whereby initiation of the return movement of said tool is delayed while it continues rotating in the work.

-2. Ahoning machine for truing the bores of blind end cylinders of internal combustion engines or the like, comprising, in combination, means for supporting a work piece to be honed, a honing tool, operating means including a rotary and reciprocatory tool spindle supporting said honing tool in position for operating upon the work piece, a, hydraulic cylinder and piston arrangement for i parting reciprocal motion to said spindle,

means for rotating said spindle continuously while the tool is in operative association with the work piece, a control valve for defining the flow direction of pressure fluid to said cylinder, means for operating said control valve including a hydraulic system embodying a pilot valve, means for controlling said pilot valve including reciprocal cycle defining stop mechanism operable as an incident to the attainment of opposite operative limits of the reciprocal cycle of said spindle, stop means connected with saidspindle serving positively to halt insertion of said tool into the work beyond a predetermined point at one oi. said reciprocalv cylinder in said one cycle limit, whereby the movement of said piston is delayed during the last part of the inserting stroke and the return stroke 7 is delayed while said tool continues rotating in defined working cycle, stop means including a part connected to said spindle for positively halting approaching movement of the spindle and tool relative to the work near one limit of said working cycle, operating means controlled by said part for initiating the return movement of said working cycle, and means cooperative with said' operating means, for restraining said return movement throughout a defined interval.

4. A honing machine of the character described, comprising, in combination, means for supporting a work piece to be honed, a honing tool, means including a rotary and reciprocatory tool spindle supporting the tool in position for operating upon the work piece, a hydraulic cylinder and piston arranged for imparting reciprocal motion to said spindle, a hydraulic circuit connectedwith said cylinder for alternately delivering pressure fluid to opposite sides of said piston' to cause the reoeiprocatory niotion of said spindle, positive stop means for interrupting the movement of said spindle and tool at a predetermined point near onelimit of said reciprocal motion, means in said circuit to control movement of said piston for slowing movement of said-spindle prior to operation of said stop means, and means coacting with said tool spindle for operating said last-mentioned means, whereby the stop means is brought, into operation by a gradual movement and jarring of the machine is prevented.

' 5. A honingv machine or the character described, comprising, in combination, means for supporting a work piece having a blind end cylinder, tov be honed, a honing tool, means including a rotary and-reciprocatory tool spindle supporting the tool in position for operating upon the work piece, means for imparting reciprocal motion to said spindle, means for continuously rotating said tool while in honing position within the cylinder, positive depth stop means for interrupting the movement of said spindle and tool at a predetermined point short of the blind end of said cylinder, said stop means including a cross arm attached to said spindle with parts extending laterally of the spindle, adjustable means on each of said parts, and stationary abutments adjacent said spindle and engageable by said adjustable means.

6. A honing machine for truing the bores of blind end cylinders, comprising, in combination, a rotary and reciprocating honing tool, means for continuously rotating said tool, hydraulically operated means including a cylinder and piston arrangement for imparting reciprocal forward and return stroking motion to said spindle, a

said auxiliary hydraulic circuit being arranged to deliver an uninterrupted rapid flow of pressure fluid to shift said main control valve immediately when'said spindle has reached the limit of its return stroke, and a manually adjustable delayed action valve in said auxiliary circuit for delaying operation of said control valve in initiating the flow of pressure fluid through said main circuit to cause the return stroke of said piston and spindle, whereby said tool will remain in operation upon a given area of the wall of a cylinder bore for a defined-interval between the'forward and return strokes.

7. In a honing machine for truing the bores of blind end cylinders, the combination of a respin'dle, control means 'forgoverning operation of said actuating means and including a hydraulic circuit having two branches, a pilot valve for alternately directing the flow of pressure fluid through said branches, one of said branches having a unidirectional valve permitting rapid flow to said control means but preventing reverse flow through said branch, a by-pass line connected at its opposite ends on opposite sides of said unidirectional, flow valve, and an adjustable delayed action valve in said by-pass line for restricting the reverse flow of. fluid around said unidirectional valve at a predetermined rate so as to delay action of said control means and thereby cause a dwell in the movement of said spindle.

, 8. In a honingmachine for truing the bore of blind end cylinders, the combination of-=a reciprocating tool carrier, a honing tool supported by said carrier, hydraulic means for reciprocating said carrier through a cycle including forward and return strokes, a control valve for controlling operation of said hydraulic means, said valve including a reciprocal plunger having opposed actuating pistons, a hydraulic circuit having branches for delivering pressure fluid to said pistons, a pilot valve for alternately directing the flow of pressure through said branches, one of said branches having a unidirectional valve permitting fluid flow toward said control valve but preventing return flow through said branch, a by-pa'ss line connected at opposite ends on opposite sides of said unidirectional flow valve, and an adjustable delayed action valve in said line allowing a return flow of fluid around said unidirectional valve at a predetermined restricted rate so asto delay action of said plunger for a given time. and thereby cause a dwell between the forward and return strokes of said carrier.

9. A honing machine of the character described, comprising, in combination, means for supporting a work piece having a bore to be honed, a honing tool, means including a rotary and reciprocatory tool carrier/supporting said tool in position for insertion into said bore, means for imparting reciprocal motion of a defined range to said carrier, rotary motion mechanism for uninterruptedly rotating said carrier while the tool is in operation in said range, positive stop means including relatively movable parts coacting with said carrier for interrupting the reciprocal movement of said carrier and tool at a predetermined point near one end of said range while permitting uninterrupted rotation of said tool, means for cushioning said movable elements againstconcussion to prevent jarring of the machine, and means operated by said stop means for effecting operation of said means for cushioning. n

10. In a honing machine for truing the bores of blind end cylinders, thecombination of a reciprocating spindle carrying a rotary honing tool,

hydraulic means for reciprocating said spindle, means for defining the limit of insertion of the tool into a cylinder bore having a blind end. a hydraulic circuit including a control valve for controlling the reciprocal movements of said spindle, and adelayed-action valve in said cir-' cuit operable as an incident to the movement of said honing tool to said limit of insertion for delaying operation of said control valve and causing a dwell in the reciprocal movement oi. the tool, said delayed-action valve including a bored rotary stem having a plurality of graduated orifices and being manually-adjustable to place any selected orifice into registration in said circuit for determining accurately the period of said alternate operations of said control valve for introducing a dwell in the movement: oi. said one support, said delayed action valve including a valve member having a plurality 01 graduated orifices, and means for adjusting the position of said member to render said orifices eflective selectively to determine the length of said dwell.

1,2. In a honing machine, in combination, a

support for a work piece to be honed, a honing tool, a spindle for supporting said tool, means for rotating said spindle, means for reciprocating the spindle through a working cycle including approach and return movements whereby the rotating tool is traversed over the surface of the work piece, limit means for positively halting the approaching movement 01' the spindle near one limit 01' said working cycle comprising a stationary part and a member connected for movement with said spindle and engageable with said stationary part, and a control device including a part also engageable by said member for initiating the return movement of the spindle.

13. In a machine for honing cylindrical surfaces, in combination, a support for work to be honed, a support for a honing tool, means for efi'ecting relative rotation of the tool and work, means for eflecting a relative longitudinal traverse of the tool and. work including hydraulically actuated means for advancing and retracting one of said supports relative to the other support, positive stop means including a member carried by said one support and engageable with a stationary stop for interrupting the movement 01 the support 'at a predetermined point, a hydraulic circuit for said hydraulically actuated means, a reversing valve in said circuit operable to reverse the flow direction of pressure fluid in said circuit whereby to control the direction or movement of said one support, hydraulic means including cylinder and piston mechanism for operating said reversing valve, pressure fiuid supply and discharge circuits for said cylinder mechanism, a pilot valve, means actuatedby said member in response to the movements of said one supportior operating said pilot valve to efl'ect alternate reversals of the connection of said supply and discharge circuits to said cylinder mechanism to operate said reversing valve, and a manually adjustable delayed action valve in said discharge circuit operative to throttle the discharge of fluid from the cylinder mechanism to delay the operation of said reversing valve and thereby cause a dwell in the movement of said one support so that the tool will remain in operation upon a given area of the work for a variable predetermined interval.

FLOYD A. SWANSON.

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