USRE23822E

USRE23822E - Power feed mechanism

Info

Publication number: USRE23822E
Authority: US
Priority date: 1951-03-07
Filing date: 1954-01-04
Publication date: 1954-05-04
Also published as: FR1079147A; BE519237A; CH321641A; US2655058A; GB723337A

Description

1954 w. A. ESCHENBURG EI'AL Re. 23,822

POWER FEED MECHANISM 5 Sheets-Sheet 2 Original Filed March 7, 1951 May 4, 1954 w. A. ESCHENBURG ETAL Re. 23,822

POWER FEED MECHANISM Original Filed March '7, 1951 5 Sheets-Sheet 5 lZI/ /72 /83 W INVENTORS WILLIAM A. ESLHENBURCT DAVID Dv PETTIG'REW CLARENCE JOHNSON ATTORN S POWER FEED MECHANISM Original Filed larch 7. 1951 5 Sheets-Sheet 5 349 0/1. 355 354 392 z 385 azz 5 NR INVENTORS j f- WILLIAM A. ESCHENBURG- DAVID D. PETTIGREW CLARENCE JOHNSON BY b 368 378 4/0 ATTORNEYS Reissued May 4, 1954 POWER FEED MECHANISM William A. Eschenburg, Plainfield, N. J., David D.

Pettigrew, Milwaukee, Wis and Clarence J ohnson, South Euclid, Ohio, assignors to Rockwell Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Original No. 2,655,058, dated October 13, 1953, Serial No. 214,284, March 7, 1951. Application for reissue January 4, 1954, Serial No. 402,197

Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

28 Claims.

This invention relates to power feed mechanisms and more particularly to an improved construction adapted primarily for use as a drill feed mechanism.

The present invention is primarily concerned with improvements in hydro-pneumatic feed mechanisms of the type disclosed in application of Clarence Johnson Serial No. 133,922 filed December 19, 1949, for "Hydro-Pneumatic Power Mechanism" for effecting rapid movement of a drill or other machine tool into and out of operative working engagement with a workpiece and relatively slow feed movement during working engagement of the tool.

In apparatus of this kind, the positioning of the machine tool with respect to the workpiece is effected by a power piston and two or more control pistons, the rate of movement of the power and control pistons being determined by one or more control valves suitably arranged in an hydro-pneumatic circuit.

It is an important object of the present invention to provide a novel construction of the elements and related circuits of such a hydropneumatic mechanism to materially decrease the size and weight of the apparatus while increasing its operating efficiency and its adaptability for production byquantity production methods.

It is a further object to provide a novel control valve for such a feed mechanism.,

It is another object to provide a novel quill and spindle construction for an hydro-pneumatic drill feed mechanism.

It is a further object to provide an improved feed rate adjusting means for a power feed mechanism. I

It is another object toprovide an improved power feed mechanism having a minimum number of compactly arranged structurally rugged parts adapted for production under quantity production methods.

It is a further object to provide a novel construction for a power feed mechanism which facilitates manufacture, assembly and repair, thereby decreasing the costs of fabrication and maintenance of the mechanism.

It is a further object to provide a novel positioning and support structure for a power feed mechanism.

It is an additional object to provide a novel construction for a hydro-pneumatic power feed mechanism which facilitates bleeding and filling the mechanism with operating fluids.

It is also an object to provide an improved drill feed mechanism which incorporates a novel I 2 means for compensating for internal volume changes occasioned by relative movements of the components of the apparatus.

Further objects will become apparent as the description proceeds in connection with the accompanying drawings in which:

Figure 1 is a side elevation of one form of an improved power feed mechanism made in accordance with the present invention;

Figure 2 is an end elevation of the mechanism of Figure 1;

Figure 3 is an enlarged sectional view taken along line 3-3 of Figure 2 illustrating the power section and a portion of the control section of the improved mechanism;

Figure 4 is an enlarged sectional view of the control section taken along line 44 of Figure 2, line 4-4 being shown also in Figure 5 for clarity of illustration;

Figure 5 is an enlarged sectional view taken along line 5--5 of Figure 1, line 5-5 being shown also in Figure 3 for illustrative clarity;

Figure 6 is an elevation of the end carp for the control section of the mechanism of Figure 1;

Figure 7 is an enlarged fragmentary sectional view taken along line |1 of Figure 2;

Figure 8 is an enlarged fragmentary sectional view taken along line 8-8 of Figure 2;

Figure 9 is a fragmentary sectional view taken along line 9-9 of Figure 8;

Figure 10 is a sectional view of the control valve taken along line Ill-ll) of Figure 4;

Figure 11 is an enlarged fragmentary sectional view of a modified control valve, adapted for use in place of the control valve of Figures 4 and 10;

Figure 12 is a right end elevation of the valve holy of Figure 11; I

Figure 13 is an enlarged fragmentary plan view of one of the valve elements of Figures 3 and 11;

Figure 14 is a sectional view similar to Figure 3 of a modified form of the invention;

Figure 15 is a top plan view of the mechanism of Figure 14 partially broken away to illustrate internal constructional details.

Figure 16 is a vertical sectional view taken along line l6|6 of Figure 15 of one of the control cylinders.

Figure 1'7 is a fragmentary sectional view of a locking mechanism for the stroke adjusting means in the mechanism of Figure 14; and

Figures 18 and 19 are sectional views of the control section of the mechanism of Figure 14 taken along lines I8-|8 and l9-l9, respectively of Figure 14.

Referring to Figures 1 and 2, I5 indicates the 3 power section of the improved feed mechanism to which a control .sectio rindicated generally at I6 is rigidly attached as BFbolts |1.- A stroke adiusting unit indicates generally at I8. through which one end of a combined power piston and drill quill-spindle unit is passes, is mounted on the front end surface of power section I5, and a speed control unit, indicated generally at 20, is mounted on the front end surface of control section l6, as more fully described hereafter. A pair of cover plates 2| are attached to the rear of the power section l as by screws 22 to protect the driving mechanism from dust, water, and other abrasive and corrosive foreign matter.

Referring now to Figure 3, and particularly to

power section

15, 23 indicates a main body housing cast from relatively inexpensive metal and having mounting flanges 24 disposed at opposite ends along its lower surfaces. As shown in Figures 1 and 2, smooth. flat, vertically extending mounting pads 25 are formed on the opposite sides of housing 23 to provide mounting surfaces by which the drill mechanism may be mounted in a variety of common machine tool supports. The pads 25 are accurately machined so that the drill unit will be held in positive longitudinal and lateral alignment with the support on which it is mounted.

The cast housing 23 is of hollow cylindrical construction provided at its opposite sides with inwardly directed annular flanges the inner annular walls of which are accurately machined to provide aligned circular bores 26 at its opposite ends. These bores are adapted to receive carefully machined high grade steel sleeves or

inserts

21 and 28, preferably with a close machine fit. To assure proper alignment of bores 26 and uniformity of size, these bores are preferably formed in a single straight-through boring operation obviating the necessity of the time consuming and expensive back boring operation and finishing machining operations that would be necessary if the housing were initially a solid casting. O-ring seals 21a and 28a are provided on

sleeves

21 and 28 respectively to maintain the respective inserts in fluid tight engagement with bore 26.

The outer surface of an annular peripheral flange portion 29 of sleeve 28 is provided with an annular groove 38 which is in communication with the inner surface of the sleeve through a plurality of circumferentially spaced ports 3|. A passage or fixed orifice 34, having an enlarged portion 35 in which a sealing ring 36 is held, passes through the upper surface of housing 23 in register with groove 36.

Sleeves

21 and 28 are maintained in abutting relation in bore 26 by shoulders 31 and 38 of annular

housing extension msembers

39 and 46 respectively which are rigidly attached to opposite ends of housing 23 as by bolts (not shown) to form cylinder heads for the power cylinder which comprises sleeve or

inserts

21 and 28.

Housing extension 38, at the end containing shoulder 31, is provided with an axially extending shoulder 4| of reduced diameter defining an annular space to closelyreceive the adjacent end of sleeves 21 and at its other end is provided with an annular motor mounting flange 42. The bore of extension 39 at the shouldered end is slightly reduced in diameter and carefully internally machined for a purpose to be presently pointed out. I

Housing 23 and its

extension members

39 and 48 are designed to receive the main power piston 4 of the power feed mechanism and the connector members adapting the power piston for connection to whatever device or element it is to, operate. In the preferred form of this invention, housing 23 and

members

39 and 48 receive the novel combined power piston and drill quillspindle unit [8 which is provided with an enlarged piston portion 43, having suitable sealing rings 44, reciprocably received within sleeve 21, in fluid tight relation thereto.

Reduced portions

45 and 48 of quill i9 respectively reciprocably engage the reduced bore of end member 39 and the inner sleeve .28. The bore of end member 39 and the sleeve 28 are provided with suitable sealing means to define sealed chambers 41 and 48 on opposite sides of piston portion 43, the shoulder 4| of extension member 39 also being provided with a sealing ring 442. to complete the seal for chamber 41.

Rotatably supported by means of a preloaded bearing cartridge indicated generally at 50, within a further reduced section 49 of quill I9, is a drill-spindle 52 having a tool chuck 53 at one end and an elongated splined section 54 at its other end. The bearing cartridge '50 is preferably preloaded to prevent random axial movee ment of the spindle 52 with respect to the quill i9 and is preferably of the general construction disclosed in United States Letters Patent No. 2,452,089. A suitable sealing structure indicated generally at 5| is provided at the forward end of quill [9 to prevent the entrance of coolant, lubricant, and other abrasive or corrosive foreign matter which may be present on the surface of chuck 53 into the interior of quill l9 and bearing cartridge 58.

A drive shaft 55 connected to any suitable power source, not shown, is provided with a keyed adapter 56 carrying an elongated driving sleeve 51 adapted to transmit power through adapter 56, to spindle 52. While sleeve 51 may be connected to adapter '56 and spindle 52 in any suitable manner, the present invention contemplates the provision of fibre inserts press fitted in the ends of sleeve 51 and respectively provided with internal splines 58 and a securing pin 59 at the end connected to adapter 56 and splines 60 alone at the end connected to spindle 52. This construction automatically compensates for any slight misalignment between adapter 56 and spindle 52 yet assures a relative free sliding, nonbinding driving connection between the axially reoiprocable spindle 52 and the relatively axially immovable sleeve 51.

Referring now to the stroke limiting unit I8, an annular'cap 63 telescopes over the reduced annular portion 64 of housing extension member 40 and is held in place by a centrally apertured end plate 65, which is secured to extension portion 64 as by screws 66. Held between plate 65 and extension 64 is an annular outboard bearing '61 which slidablysupports quill portion 49 and is notched to receive a brass scraper ring 68 and a brass bushing 69.v A grease fitting 13 is positioned in cap 63 through which grease is supplied to the annular space between cap 63 and extension portion 64 and through registering passages 14 and 15 in extension portion 64 and bearing 61 respectively to an annular groove sufiiciently free to permit relative rotative move-.

ment around housing extension 48.

The forward stroke of quill-spindle unit I9 is determined by the position of an annular stop 11 which threadedly engages the internal surface of extension portion 84 and is provided with an axially extending slot 18. Received in slot 18 is a rod 19 which is rigidly attached as by a screw 8| to an annular collar 88 which is rotatably mounted within end member 48. An idler gear 84 is mounted for rotation on a shaft 85, both of which are received within slots in housing extension 48. Gear 84 meshes with internal gear teeth in cap 53 and with external teeth arranged around the periphery of the reduced end portion of collar 88. Rotation of cap 53 thus produces opposite rotation of collar 88, rod 19 and stop 11 effecting axial movement of stop 11 along portion 84 of extension 48 to vary the range of movement of quill I9. As shown in Figure 1, a scale 82 is provided on cap 83 for cooperation with a reference mark 83 on the stationary housing extension 48 to assure rapid and accurate selection of the desired drill stroke. A locking screw 88 (Figure 1) extends through housing extension 48 into collar 88 to lock the stroke adjusting 'unit I8 in its adjusted position. I

The stroke adjusting unit I8 is here described only so far as is necessary for a complete understanding of the present invention and is more fully disclosed and claimed in copending application Seria No. 133,922 of Clarence Johnson filed December 19, 1949, for Hydro-Pneumatic Power Mechanism" and owned by the assignee of this application.

Referring now to the control section I5 (Figures 3-7), 81 indicates a cast housing of shell like form, the central portion of which is open at one end and along its lower surface. The housing 81 is secured to the power section 23 by bolts I1 (Figures 1- and 2), with a carefully machined lower surface of the closed end of housing 81 in fluid tight engagement with a similarly machined upper surface of housing 23 at a point adjacent the passage 34 in the latter.

A machined surface of a cast cap 88 (Figure 6), having a pair ofcast frusto-conical recesses 89 and 98 is secured to the machined open end of housing 81 by means of bolts 9I (Figures 1 and 4). Machined

cylindrical recesses

92 and 93 terminating in machined shoulders 92a and 93a respectively are concentrically formed around the respective recesses 89 and 98.

Threaded passages 89a and 98a extend through the cap 88 centrally of the recesses 89 and 98. The passages 89a and 98a are normally closed by threaded plugs 89b and 98b, respectively. An upwardly and rearwardly inclined passage 980 extends through cap 88 into the top of recess 98. Passage 98c is normally closed by a plug 98d. The passages 89a, 98a and 98c are provided to facilitate filling the mechanism with hydraulic fluid as more fully explained below.

I threadedly engages a reduced extension I88 of the valve body and draws flange 95 into abutting engagement with a machined recess in the inner side of the forward wall of housing 81. Sealing rings I8I are maintained in fluid tight engagement between valve body 95 and bore 98 the 6 outer ring I8I being held in place by a washer I82 clamped. between nut 99 and the outer surface of housing 81. A machined steel cylindrical insert I03 is clamped between an annular re-- cess 98a in flange 95 and shoulder 92a in the cap 88. Suitable sealing rings I84 maintain the cylinder I83 in sealing engagement at its opposite ends with recess 92 and the annular outer surface of the recess 95a in the flange 95.

Sealingly received within a bore I on the forward end of housing 81, 15a machined steel annular recess "Na in flange I88 of body I85 in' the same manner as cylinder I83. A pair of identical free pistons H3 and II4 having centrally disposed plugs II3a and II4a, respectively, are reciprocably received in cylinders II I and I83, respectively. Each of the pistons has an O-ring seal H5 in its head portion and a reduced portion IIB intermediate its ends to reduce the area of frictional engagement between the pistons and the respective cylinder walls. A fluid passage I I1 is provided in each piston to connect the inner and outer surfaces of the portion HE.

A movable abutment rod II2, extending through bore I81 into the interior of cylinder I l I, is adjustably threaded into the outer reduced end of bore I81 and is held in adjusted position by a lock nut N29. for a purpose to be explained. As clearly seen in Figure 4, abutment rod H2 is aligned with plug I I3a of its associated piste I I3.

A drilled passage I I8, in register with passages 34 and 35 extends upwardly into housing 81 and is the only fluid passage connecting the control section I6 with the power section I5. At its upper end, passage !I8 is in communication with a drilled passage II9 (Figures 4 and 5) extending through the forward wall of housing 81. Passage I19 is closed at its outer end by a ball check filler valve I28 consisting of a valve body I2I threaded into the outer end of passage II9, a spring loaded ball I22 and a cap I23. Valve I28 provided a one way filler passage closed throughout normal operation of the drill mechanism, being opened only for initially filling and refilling the system with a suitable hydraulic fluid.

Passage H9 is provided at its inner end with an enlarged portion I24 in which one end of a machined tube I25 (Figure 4) is sealingly received. The opposite end of tube I25 is sealingly received within an enlarged portion I2Ea of a passage I28 extending through cap 88 drilled in axial alignment with passage H9. The passage I25 is normally closed by a plug I28b threaded into cap 88. The length of tube I25 is preferably selected so that it will be firmly clamped against the shoulders formed by the respective drilled portions I24 and I25a as cap 88 is drawn into abutting engagement with housing 81 by bolts 9|. Communication is established between recess 98 and passage I26 through a drilled passage I21 in cap 88.

At a point intermediate its ends, passage H8 is in communication with an annular groove I28 in valve body 95, as best shown in Figures 4 and 5. As shown in Figure 3, an internal annular 7 groove I29, formed in bore 91 of valve body is connected to groove I20 through a plurality of clrcumferentially spaced radial ports I30. A valve core I35, having an internal bore I30, is positioned within bore 91 of valve body 95 by means of external threads I31 which engage internal threads I30 within extension I00 of valve body 95. A keying pin I39 within extension I00 extends into an annular groove I40 (Figures 3 and 11) in the valve core to limit axial movement of the valve core. Communication between internal groove I29 and bore I30 is established through a plurality of angularly spaced arcuate grooves I43 (Figures 3 and in valve core I35. The inner end ofcore I35 lies adjacent a triangular metering orifice I44 (Figures 11 and 13) in the wall of a reduced portion I45 of valve body 95. A plug I40 is threaded into the inner end of reduced portion I45. A ball check valve I41 is held normally in resilient fluid tight engagement with a central bore I40in cap I40 by a spring I49 positioned between ball I41 and one end of bore I30-in core I35.

Mounted on the outward end of valve core I35 is an adjusting knob I50. Relative movement between knob I50 and core I35 is prevented by a set screw I5I extending through knob I50 onto core I35. Rotation of [knot] knob I50 will, due

to the threaded connection between core I35 and body 95, move core I35 axially to control the effective size of the uncovered portion of metering orifice I44 for a purpose fully explained hereafter. Due to the shape and arrangement of orifice I44 with respect to core I35 and this threaded connection extremely fine adjustments of the metering orifice can be effected.

A plurality of locking screws I52, extending through knob I50 onto extension I00 of valve body 95, is provided to prevent relative movement between knob I50 and body 95 after a predetermined adjustment of'the position of core I35 has been made. The outer ends of screws I52 are preferably disposed below the surface of knob I50 to accommodate a deposit of suitable sealing compound I53 to prevent tampering and unauthorized adjustment of the valve after it has been set up for a particular job if this is desired.

A scale I54 isprovided on the outer surface of the inner end of knob I50 for cooperation with a suitable reference mark I54. on housing 01 to facilitate predetermined fine and accurate adjustment of the valve assembly.

Referring now particularly to Figures 4 and 5, a drilled passage I55 extends vertically upward into housing 81 and is closed at its lower end by housing 23. At a point near its lower end, passage I55 is in communication with a passage I50, similar to passage II9, drilled through the end wall of housing 01. Passage I50 is closed at its outer end by a threaded plug I51 (Figure 2) and is provided at its inner end with an enlarged portion similar to enlargement I24 of bore H9 in which one end of a machined tube I59 is sealingly received. The opposite end of tube I59 is sealingly received within an enlarged portion I50 (Figure 6) of a passage IOI drilled intocap 00' in axial alignment, with passage I 50. The length of the tube I59 is preferably selected so that it will be clamped between cap 00 and the forward wall of housing 01 upon application of cap 00. Fluid communication is established between passage IOI and recess 09 by means of a drilled passage I52 in cap 00.

At a point adjacent its upper end, passage I55 opens into bore I05 at a point in register with an position. A second annular groove I13, separated from groove I00 by a land I14, is in communication with bore l01through a series of spaced ports I15 (Figure 4) and through passage I10 in housing 31 with a pipe I11 which is threaded into passage I10 (Figure '7) and leads to a source of air under pressure.

Referring now to Figures 8 and 9, the space 41 to the left of power piston 43 is in communication with a conduit I10, which passes through cover plate 2|, is threaded into member 39, and leads to a source of air under pressure through drilled passages I19 and I19a in housing extension 39.

A guide rod I00, having opposed flat surfaces IOI, and opposed arcuate surfaces I02 (Figure 9), which latter slidingly engage a. bearing sleeve I83,

pressed into an enlarged portion of bore I19, is

pressed into a recess I04 in piston 43. It will be seen that while rod I80 prevents rotation of piston 43, it allows free longitudinal movement of the piston and free communication between conduit I10 and space 41 at all times.

The operation of the mechanism thus far de scribed is as follows:

Chamber 48, of power section I5, passages 34, H0, I26, I21, I28, I29, I30, bores 91 and I30, the space to the right of piston II4, tube I25 and the space to the left of piston II3 are filled with a suitable hydraulic fluid or other liquid of low viscosity.

The filling operation is preferably performed with plug I20b and either plug 90b or 90d removed so that air entrapped in the hydraulic circuits will be bled from the highest point in the circuit. The power piston is held in its fully forward position duringfilling. The piston II l is held in its corresponding fully forward posi tion by a suitable push rod inserted through passage 09a after removal of plug 89b. The abutment member I I 2 is screwed inwardly to hold the piston H3 in its rearward position so as to be in proper operating position with respect to the preselected position of pistons 40 and H4. Fluid may then be introduced through conduits 2I5 or plug I20 forcing air out of the hydraulic circuit through passages I20, 90a and 900. As soon as a steady flow of fluid through these passages is observed the passages are closed. As additional oil is'supplied, piston H4 is permitted to move to its full left position at which point the system is completely filled. As will be seen from Figure 3 there is a substantial volume of fluid in cylinder I03 to the right of piston II4 when the power piston is fully retracted. This space, which is completely filled by the above described method constitutes an oilreservoir to assure comas desired. Since the extent of sure (not shown) or to exhaust (not shown) to thereby alternately connect chamber 41 of power section I and passage I13 or the space to the right 01 piston I I3, the space to theleft of piston II4, passages I55, I56, I62, tube I59, and passages I66, I61, I13, I and I01 to air under'pressure or exhaust.

Assuming conduit I19 is connected to a pressure source conduit I11 connected to exhaust, and pistons 43, I I3 and I I4 to be in the position shown, air under pressure will be supplied to chamber 41 at the rear of piston 43. This air acts to move the piston to the right, advancing chuck 53 which carries a suitable drilling implement (not shown) to the right toward a workpiece. As piston 43 moves to the right fluid will be displaced from chamber 48 through passages 34, H8, H9, tube I25, and passages I26 and I21 into the space to the left of piston II3. Since the space to the right of piston II3 is vented to atmosphere through conduit I11, piston I I3 will move rapidly to the right at a speed determined by the size of fixed [passage] orifice 34. Pistons 43 and II3 will continue to advance rapidly to the right until piston I I3 abuts rod 2. The position at which piston I I3 abuts rod H2 is, of course, determined by the adjusted position of rod 2 and thus can be varied within wide limits.

When piston II3 abuts rod II2, fluid can no longer leave the upper end of passage I I8 through passage H9 and tube I25. However, as piston 43 is still being urged to the right under the influence of the pressurized air in space 41, the fluid to be displaced will now follow a secondary path from passage IIB through passages I26, I29, I30,

I43,'and bore I36 of valve body 95 (ball I41 beand metering then through space to the right of piston to the left of piston H4 is vented to atmosphere through passage I62, tube I59, passages I55, I66, I61, I01, I13 and conduit I11, the piston H4 is free to move to the left under the influence of the fluid passing through metering orifice I44 at a rate determined by the size of orifice I44 which in turn depends upon the position of valve core I35. It will be understood that by varying the shape of orifice I44 the character of the flow adjustment effected per unit of linear movement of core I35 can be varied movement of controlled rate depends upon ing held on its seat) orifice I44 into the H4. Since the space piston H4 at this the setting of rod to be displaced, which is always maintained at a sufiicient volume to permit the maximum permissible movement of piston 43, piston 43 will continue to advance until the forward shoulder of portion 46 abuts adjustable stop 11. It, therefore, will be seen that the advancement of piston 43 and chuck 53 through a preselected stroke determined by stop 11 is efiected at two controlled speeds, and that by suitable adjustment of stop rod II2, the entire stroke as well as the portions of the stroke efiected at each speed are subject to ready and precise control. In practice, the drill head is adjusted so the drill is carried to a point just short of the surface of the work at high speed and advances into the work at the controlled lower feed speed.

To return the drill to its initial position, conduit I11 is connected to a suitable source of air under pressure (not shown) and conduit I16 is connected to exhaust. Air under pressure is then supplied to the right side of piston II3, forcing the piston to the left and displacing fluid from the left end of cylinder [I I3] 111 through H2 and the amount of liquid 10 [passages] passage I21, tube I25, [and passages] passage H8 and fixed orifice 34 into chamber 46. Since the chamber 41 is vented to atmosphere throughpassage I19 and conduit I13, piston 43 willmove rapidly to the left at a speed determined by the size of fixed orifice 34. Air under pressure is simultaneously supplied from conduit I11 through passages I13, I15, I01, I61 and I66 of I06, passages I55, I55, tube I59 and passages I60 and I62 to the leftside of piston II4 urging it to the right. The fixed orifice 34 inherently maintains a substantial pressure differential between its upstream and downstream sides. Thus, during the retracting movement of the power piston 43, a pressure is maintained against the right side of the ball check 147 which is effective, together with the spring 149, to maintain the ball check seated until the piston 113 seats against cap 88. Because of the back pressure created by orifice 34 the spring 149 need not be of suflicient strength to main- 'tain the ball checked seated against the full pneumatic pressure effectively transmitted to its left side by piston 114. [However] Thus, during the movement of piston I I3, the pressure differential across ball check I41 is insufilcient to unseat the check valve and there will be no flow through passage I48 and due to the [substantial equality of pressure on the opposite sides] back pressure created by orifice 34 on the right side of passage I44, there will be no appreciable flow through passage I44 and consequently, piston II4 will be held substantially stationary.

When piston II3 abuts against cap 68, the pressure-on the right side of orifice I44 and ball I41 will immediately be substantially decreased due to the continued bleed through fixed orifice 34. A pressure differential will then be established across ball I41 sufficient to over come the force of spring I49. Ball I41 will then be unseated, and fluid will'fiow through passages I43 and I44, bores 91 and I36, passages I43, I29, I30, I26, H8, and 34 into chamber 48 forcing piston 43 to the left. This movement will continue until pistons H4 and 43 are returned to their original positions, as shown, in Figures 3 and 4. Due to the back pressure created by orifice 34 during movement of piston 113 which prevents the opening of ball check 147, piston 113 will complete its stroke and return to its initial position before piston 114 has undergone any appreciable movement. This sequential movement assures return of the control pistons to their initial positions so that successive cycles of opera tion will be of uniform character. It will be noted that, although pistons II3 and H4 move sequentially, the entire Withdrawal stroke of piston 43 is effected at a rapid, substantially uniform, rate.

In certain machining operations, it is desirable that the entire advancing and withdrawing stroke be eilected at the relatively slow feed rate. To this end, the valve assembly 95 of Figures 3 and 4 may be modified as shown in Figure 11, wherein the valve assembly there shown is iden: tical to the valve assembly described above except for the construction of the valve core and the components assembled therein. In its external construction, valve core I35a (Figure 11) is identical to valve core I35 (Figures 3 and 4) except that transverse slots I and I9! of differing depth are provided across its outer end. An extension I92 of a control knob I93 is shaped so that it may be received in either of the slots I90 and I9 I. Threaded into a central aperture in 11 knob I93 is a valve actuator stem I94 reciprocably received within an internal'bore I95 provided in core I 35a. An enlarged portion I96 of stem I94 is reciprocably and sealingly received within an enlarged counter-bore I91 of core I35a. A spring I98, coiled about portion I96, is compressed between ball I 41 and the end of a second enlarged bore I99 in valve core I35a, spring I98 and bore I 99 respectively corresponding to spring I49 and bore I36 of Figures 3 and 4. A second spring 200, coiled around stem I94, is compressed between the end of bore I91 and the shoulder formed by the enlarged portion I96 01' the stem.

When knob I93 is withdrawn and extension I9! is placed in slot I 9|, as shown in the dotted line position of Figure 11, valve stem I94 and enlargement I96 thereof-is moved to the rightto the dotted line position. In this position, the valve assembly functions exactly as the valve assembly described above in connection with Figures 3 and 4. However, if the knob I93 is allowed to seat in slot I99, the knob and stem occupy the full line position of Figure 11 and the enlarged end I95 of stem I94 is seated on ball I41 under the influence of spring 200 which is of suflicient strength to maintain ball I41 seated throughout the operating cycle of the drill head. Then, if abutment rod III is moved to the left so that it holds piston H3 against the left end of cylinder 93, it will be seen that the only path provided for oil leaving and entering the chamber 48 will be through metering orifice I 44. Thus, all movement of piston I43 on both the advance and return strokes will be effected at the feed rate determined by efiective size of orifice I44. If desired, the abutment rod II2 may be moved to the right to allow any desired movement of piston II3. If the knob I93 15 then placed in its full line position (Figure 11), the initial portions or both the advancing stroke and the withdrawal stroke will be eifected at high speed, and the final-portion will be at feed speed. The relative length of the high and low speed portions of the stroke will be determined by the amount of travel of piston H3 and can be varied at will by suitable adjustment of rod H2.

As the piston 43 reciprocates, it will be apparent that the volume of the space Zlll between the forward shoulder of portion 46 of the piston and the stop 11 will vary and that this variation will be accompanied by undesirable pressure resistance in this space. Particularly, as the piston is rapidly withdrawn, a vacuum will be produced in space ZllI which may draw coolant and lubricant and in some cases, small metal chips which may be on the surface of quill I9, into the space with consequent damage to the accurately machined components of the drill head. To stabilize the pressure in the space 20 I, a vent comprising registering drilled

passages

294 and 205 in head 40 and the base of housing 23, respectively, is provided. A fine screen filter 206 is connected to the outer end of the vent passage to maintain the chamber free from grit and dust, which may be present in the surrounding atmosphere.

The mechanism as a whole readily lends itself to semi-automatic or fully automatic control. By the proper employment of suitable switches and relays effective to control solenoid actuated valves in conduits I11 and I18, the mechanism can be automatically operated in response to a number of control factors. pressure switch may be connected to the forwa to the, abutment of the quill against stop 11 or the build-up of excessive pressure at the drill point. Means responsive to the drill torque or to the motor current may alternately be provided to signal a withdrawal of the drill. In some cases, it will be desirable to combine pressure and torque responsive control means. Where drill pressures and torques may be too small to provide reliable control, an independent timer may be used to control the system. It may also be desirable to supplement the timer with a pressure switch, the latter operating only on completion of the drilling operation or under condition of severe overload.

Advance of the drill may be initiated by a switch which is actuated by the quill in its withdrawn position. I

A typical automatic switch system is illustrated briefly in Figure 3, wherein numeral 2| 0 indicates a housing, supported by any suitable means (not shown) accommodating a two-position switch, set to one position by mechanical action and to the other position by a fluid pressure responsive element. The switch, for example, may be mechanipally activated by depression of a pin 2 I I, extending through housing extension 39 at a point opposite the end of end portion 45 of quill I9 in its fully withdrawn position. When the switch is so activated, leads 2|! and 2" are energized to activate suitable solenoid-operated valves (not shown) to connect conduits I18 and I11 to pressure and exhaust, respectively, initiating an advance stroke of quill unit I9. When forward movement of the .quill is arrested by stop 11 or by excessive pressure at the drill point, the pressure in space 48 will rapidly decrease. This pressure decrease is transmitted through passage 3I in sleeve 28, a drilled passage 2 in housing 23, and a fluid conduit 2I5, to the pressure responsive switch element in housing III). Leads 2I6 and 2 I 1 are then energized, reversing the position of the valve in conduits I11 and I18, efiectinga withdrawal of the quill unit. The cycle may be repeated indefinitely or may be interrupted at any point byoperating suitable manual switches (not shown) which break the circuit in either leads 2I2, 2I3 or 2I6, 2I1 preventing energization above, and application Serial No. 137,605, of

FOr example, a conventional Clarence Johnson for Switch Mechanism and Control Circuit for Hydro-pneumatic Power Mechanism, filed January 9, 1950, both owned by the assignee of the present application.

The modified mechanism illustrated in Figures 14 to 19 is, in its major aspects and in function. substantially, the same as that above described in connection with Figures 1 to 13, and accordingly, insofar as possible the same reference numerals are used to indicate similar parts in this modification.

A number of detailed refinements have been incorporated in the modified mechanism to further reduce manufacturing and assembling costs, assure the elimination of air pockets in the hydraulic circuit, and to facilitate bleeding and filling these circuits. Because of the close simi-- close fit within sleeve 261.

13 the mechanism illustrated in Figures 14 to 19 will be described only insofar as. is necessary to explain the points of distinction between the two modifications.

Referring now to Figure 14, 250 indicates generally the power section of the modified feed mechanism to which a control section indicated generally at 252 is rigidly attached as by studs 253 and nuts 255 (Figure 18). A stroke adjusting unit indicated generally at 254 through which one end of the combined power piston and drill quill spindle unit 256 passes is mounted on the front end of the power section 250. Suitable cover plates for the mechanism, not shown, may be provided as required to protect the mechanism from objectionable foreign matter.

The power section 250 includes a main body housing 258 of hollow shell-like cylindrical construction provided with suitable external mounting and aligning pads previously described. Cylindrical inserts or sleeves 260 and 251 are received within the body section 258, the former being provided with a sealing ring 262 at one end. Sleeve 261 is adapted to receive an outer sealing ring 263 and an inner sealing ring 265. A washer 255a is desirably formed of soft metal such as Babbitt metal, so any particles entering through sleeve 261 will be ground into the washer to prevent scoring the quill. [washer] Washer 265a retains the ring 265 in proper position in sleeve 261. The outer surface of sleeve 261 is provided with an annular groove 266 into which a plurality of angularly spaced drilled passages 261 extend to establish fluid coi. munication between the interior of sleeve 260 and the outer periphery of the sleeve 261. To facilitate installation of the sleeve 261 without damage to the machined inner surface of the body section 258, a slight clearance is provided at the peripheral flange portion of sleeve 261 extending inwardly oi the groove 266. It will be noted that sleeve 261 is of substantial length to provide an adequate bearing support for the power piston 268.

Housing extensions or cylinder heads 210 and ll, respectively, close the rear of the body section 258 to which they are rigidly secured as by bolts not shown in a manner previously described. The power piston 268 is and front ends of generally the same construction as the piston 46 previously sleeve 269 is press fitted onto the reduced for ward portion of piston 268 and reciprocates with Also a plurality of circumferentially spaced passages 212 are provided to establish communication between the interior of the piston and the enclosed chamber 214 within the stroke adjusting unit 254.

described except that a machined The interior of the piston 268 is also connected 2 to the expansible chamber within the axially fixed drive'sleeve 216 through spaced passages 211. Thus the spaces 214 and 215, the volumes of which vary inversely in substantially equal amounts during movement of the power piston, are vented to each other and changes in the internal volume of the power section are thus internally compensated for.

A vent port 218, into which a dust filter 219 is threaded, is provided to vent the power section to accommodate any slight inequalities which may exist in the variations in volume of the spaces 2'14 and 215.

A spindle 201 is rotatably supported within the piston 268 by means of a sealed pre-loaded hearing cartridge indicated generally at 262. An annular outer pre-loading' member 283 is threaded into the forward end of the piston 260, the inner pre-loading member 284 being threaded onto the forward end of the spindle. The forward end of the spindle is enclosed by a dust cap 285 also threaded onto the end of the spindle, the cap 285 providing a labyrinth seal at the forward end of the bearing.

The simplified stroke adjusting mechanism 254 includes a cap 286 which telescopes over the reduced forward section of the closure member 211 and is fixed against axial movement by a plurality of cap screws 288 threaded into cap 286, and having sharp extensions which extend inwardly of cap 286 into a peripheral annular groove in the member 211. An annular cover plate-and sealing ring structure 290 is secured in an annular recess formed in the forward end of the cap 286 as by screws 291. Press fitted into a drilled bore in the cap 286 is rod 294 which extends axially through a notch in an annular stop nut 296 threaded into the bore of closure member 211. It will be seen that when cap 286 is rotated, nut 296 will be threaded axially into or out of space 214 and will thus provide an adjustable stroke limiting abutment for the forward shoulder 291 of the power piston. In this connection, it will be understood that rod 294 is disposed radially outward a distance sufficient to clear sleeve 269 of piston 260.

A means for locking the cap 286 in its adjusted position is illustrated in Figure 1'7 which is a sectional "view in a plane approximately 30 from the vertical behind Figure 14. 'The upper surface of member 211 which is fiat and appears nearly flush with the cap 286 in Figure 14, is offset with respect to the cap in the plane of Figure 1'? so that a shoulder is formed therebetween. A locking stud 302 is threaded into the corner of this shoulder at an angle of approximately 45. A lockwasher 304 on stud 302 is provided with a beveled surface which engages the cap 286 and the vertical shoulder of member 211 and thus locks the cap in adjusted position. A conduit 29B threaded into a passage 299 which leads to the forward side of the piston 268 is provided to supply a volume of pressure fluid for the automatic actuation of a suitable control section which may take any of the forms previously described.

Except for the above noted features, the power section 250 is substantially the same as the power section 15. The single passage 310 leading to annular groove 266 also communicates with the novel control section 252 now to be described.

The shell-like control section 252 is comprised of three members, a main body section 320, a cap 322 and cover plate 324. The body section 320 comprises a relatively thick forward wall 325 which joins at its lower edge an integra1 right angularly extending section 326. The member 320 is machine finished along a portion of the outer surface of section 326 so as to tightly engage the upper machined surface of the power section housing 258 to which it is secured by the provided in the inner end of the central bore in the valve body 338 to guide the ball check valve I41 into and out of seating engagement with plug I 46'. from the previously described core I35 only in that the spring receiving bore 336 is provided The adjustable valve core 334 differs with an axial extension 331 which is in fluid com- 325 to hold a' sealing ring 396 in place in bore 329. The interior bore of the cylinder head 348 communicates with the air circuit of the mechanism through circumferentially spaced passage 349 and an annular groove 358 in register with air circuit passages 01'. the wall 325. A sealing ring 352 is provided to prevent leakage toward the inner surface of the wall 32 5. The movable abutment member 354 is threaded into the head 348 and adjustably locked in place by a nut 355.

One end of a machine steel cylinder 356 is telescoped over a reduced end portion of cylinder head 348 against an annular machined shoulder.

. The opposite end of the cylinder 356 is received within a machine bore 368 in the cap 322. The opposite ends of a similar cylinder 362 are likewise respectively telescoped over an annular machined shoulder on the valve body 338 and received within a machined bore 364 in cap 322. S-pringwashers 366 are positioned between the ends of the

cylinders

356 and 362 and the bottom of the respective recesses in the cap "322 in which they are received. The washers are provided to positively position the cylinders despite small variations in distances between the seating surfaces on which the cylinders are supported.

The cap 322 is secured at spaced points along its lower surface to the horizontal section of the body 328 by bolts 368 (as shown in Figure 15), machined surfaces being provided along the mating lines or the cap 322 and the body 328.

At a point slightly ofl-set from the mid-point of its upper surface, the cap is secured by a bolt 318 to a spacer rod 312 (Figure 15) the opposite end of which is threaded into the wall 325 of the body 328. The effective length of the rod 312 is fixed by a lock nut 314. The respective lengths of the rod 312 and the cylinders 356' and 362 are selected so that when the cap is properly installed a slight clearance is preferably provided at the washers 366 whereby the cylinders are yieldingly urged toward their respective opposite end mounting surfaces.

Clamped in a similar manner between the cap 322 and the wall 325 are machined steel tubes 316 and 318 which communicate respectively with the hydraulic and air circuits of the mechanism in the same manner as tubes I25 and I59 described above. I

The cover plate 324 extends over the top and sides of the control section between the cap 322 and the wall 325 and is secured at its bottom edge to the body section 328 by plurality of screws 319. The opposite ends of the cover 324 are received in peripheral recesses in cap 322 and wall 325 so as to be flush therewith.

Recinrocably received within the cylinder 356 is a solid free piston 382 which is provided with a sealing O-ring 384. A plug 385 is pressed into the center of the forward face of the piston 382 in alignment with the abutment member 354. A free piston 388, having sealing rings 361 is reciprocably received in cylinder 362 and is provided with a central recess 388 of slightly greater diameter than the rearward extension of the body 338. The depth of the recess 388 is such that in the full forward position of the piston (which is never reached in the normal operation of the mechanism the normal forward position of the piston 386 being illustrated in Figure 14), plug I46 abuts the bottom of the recessand the port I44 is left partially uncovered.

As best illustrated in Figures 16 and 19, the

machined recesses

368 and 364 in cap 322 which receive the ends of the

cylinders

356 and 362 are provided with reduced

extensions

392 and 394, respectively, With each having a rearwardly and inwardly sloping wall so that the region of great est depth is disposed upwardly and inwardly of the axis of the respective cylinders. in Figure 14, a bore 396 extends through cap 322 into the recess '394 in alignment with the axis of cylinder 362. This bore, which is normally closed bya threaded plug 398, serves as a passage through which a push rod may be inserted to position the piston 386 against plug I46 during the filling operation as is explained more fully below. The end of hydraulic tube 316 is in communication with recess bore 484 which extends to the outer surface of cap 322 and is closed by a threaded plug 486. A similar inclined passage 488 connects the air tube 318 and recess 394 and ed plug 418. I

A rearwardly inclined passage 2 (Figure 16) connects the upper portion of the recess 3 92 with the exterior of the cap and is closed by a threaded plug 4. The function of the several passages in the cap 322 will be readily understood from a description of the method of filling the mechanism with hydraulic fluid presently to be described.

It will benoted that the filler plug I28 has been omitted in the modified apparatus, the hydraulic fluid being supplied through passage 299 in the power section housing. In filling the mechanism, two factors are of particular importance. First, the

control pistons

382 and 386 must occupy their proper relative positions with respect to the power piston 268. Second, since the precise operation and control which characterizes the mechanism is dependent in large measure on the action of the incompressible hydraulic fluid particular care must be taken to prevent the entrapment of air in the hydraulic circuit. 'The modified mechanism of Figures 14 to 19 isconstructed to enable the ordinary mechanic to control both of these factors with case.

To begin the filling operation, the power piston is moved to its fully forward position and plugs 398, 486 and 4 are removed.

A push rod is then inserted through bore 396 to place the piston 386 in its fully forward position. Abutment rod 364 is screwed into cylinder 356 to hold the piston 382 in its fully retracted position. Hydraulic fluid at moderate pressure is supplied through passage 299 to the space at the forward side of the power piston and flows upwardly through groove 268 thence through passage 3l 8 into the control section where it flows through passages previously described to the for- As shown I 392 through an inclined is closed by a threadcases 17 ward side of piston I86. Because of the small clearance provided at the forward side of this piston a very small amount of air will be entrapped there. The oil also flows along tube 816 and through the passage 404 into space 392. Since the bore 404 is at the highest position in the system, all the air is bled ahead of the inflowing hydraulic fluid except the small amount entrapped at the forward side of piston 386. To remove this air the power piston 26B and control piston 386 may be reciprocated through a number of cycles manually. To provide the necessary fluid reservoir at the forward side of piston 386 as illustrated in Figure 14, plugs 406 and 4 are installed and additional oil is added while piston 386 is permitted to move to its full left position. Then by installing the plugs 398 in cap 322 and disconnecting the fluid supply lines the apparatus is ready for operation. It is [at the highest position in the system whether the mechanism is] to be noted that either the passage 406 or M2 is at the highest position in the system whether the mechanism is installed in a horizontal'or a vertical position. Thus the method of filling described will be equally effective in either position.

The operation of the device of Figures 14 to 19 is identical with the exception of the back feed to that previously described in connectionwith Figures 1 to 13. Consequently, only the back feed operation will be described here.

It will be recalled that retraction of the power piston at the slow feed rate to provide back feed as desired was accomplished in the apparatus of Figures 1-13 by the selective positioning of rod [I9] 196 (Figure 11).

The modified mechanism of Figures 14 to 19 may be adapted for back feeding either by the incorporation of a similar mechanism or by the substitution of a solid plug (not shown) for the apertured plug I46 and the removal of the associated ball check valve. During the feed portion of stroke in either direction the hydraulic fluid thus flows only through the feed port I44.

It is to be understood that because of the basic similarity of the two forms of the invention. any of the modifications described in connection with Figures 14 to 19 may be readily incorporated in the mechanism of Figures 1 to 13.

It will be apparent from the foregoing that the compact drill mechanism is ideally suited for manufacture with low cost, high speed factory mass production assembly techniques.

Both the hollow cast housings for the power section and the control section require a minimum of machining to put them in finished form. Such machining as is required may be performed in sim le operations. For example, machining of the interior of the hollow cast power section housing merely requires a single straight through boring operation since all of the interior finished surfaces are of the same diameter and consist merely of aligned annular seating surfaces. The passages and apertures in the forward wall of the control section are also respectively of uniform diameter and readily accessible for ordinary through boring operations to simplify the finishing operation. The mating surfaces on the two housings are of minimum area and are all readily accessible external surfaces whereas the cylinder and tube abutment surfaces of the control housing are accessible also by ordinary through or count-erboring tools. None of these drilled passages, bores or the like is of inordinate length requiring special attention or complicated 18 chucking of the housing to perform the drilling operations.

Further economies are affected by providing separable working parts of high grade steel thereby minimizing costs while assuring long life. Easy removal and replacement of these parts, such as the cylinders, pistons, and other parts subject to the most rapid wear is also obtained. The cylinders and pistons of the apparatus of Figures 113 are of identical construction so they may be made on one machine set up which substantially reduces the cost of manufacture and obviates the necessity for maintaining inventories of a number of dissimilar parts and the possibility of misassembly incident to use of dissimilar parts.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by the United States Letters Patent is:

1. In a hydro-pneumatic mechanism having a power section containing a power piston and a control section containing a plurality of control pistons: separate shell-like housings for each of said sections having fluid passages at their opposite ends; an external machined mounting surface on one of said housings; a mating external machined mounting surface on the other of said housings; means for connecting said housings in assembled relation and maintaining the said surfaces in engagement with certain of said passages in register; open ended, cylindrical inserts for each of said housings adapted to respectively reciprocably receive said pistons and each having one end in fluid communication with said registering fluid passages to form a closed fluid reservoir and having their opposite ends in communication, through others of said fluid passages with a source of pneumatic pressure adapted to be selectively applied to said power piston or said control pistons to effect desired operation of said mechanism.

2. In a hydro-pneumatic mechanism: a power section, comprising a first cast shell-like housing for said power section having a machined cylindrical bore, a machined power cylinder mounted in said bore, machined cylinder heads positioned at opposite ends of said bore in fluid tight engagement with said power cylinder, and a power piston in said cylinder; a control section for regulating the movement of said power piston, comprising a second cast shell-like housing for said control section having an open end and a wall at its other end, a plurality of machinedcontrol cylinders mounted in said second housing, re spective control pistons in said respective control cylinders, respective machined inserts mounted in and extending through said wall for supporting one end of said respective control cylinders, a cap closing the said open end of said second housing, and a-plurality of machined clamping surfaces in said cap for clamping said control cylinders against said inserts; securing means comprising machined mating surfaces on each of said housings for securing said housings in assembled relation; and fluid piston and said passages in each of said housings interconnecting said power 19 control pistons for tandem movement by said fluid in said fluid passages.

3. In a hydro-pneumatic mechanism having a power piston: a control section for regulating the movement of said power piston comprising, a shell-like housing having fluid passages at one end, one of said passages communicating with .said power piston; a plurality of open ended cylinders positioned within said housing; a control piston reciprocably received in each of said cylinders; inserts in said one end of said housing having machined surfaces for sealingly engaging andsupportingoneendofeachofsaidrespective cylinders; a cap for said housing having machined surfaces for sealingly engaging and supporting the opposite end of each of said respective cylinders; and fluid passages in said cap and said inserts through which respective opposite ends of said cylinders are placed in communication with said one fluid passage to form a closed fluid chamber and the respective other ends of said cylinders are placed in communication with a source of pneumatic pressure adapted to be selectively applied to said control pistons to eifect desired operation of said mechanism.

4. In a hydro-pneumatic mechanism having a power piston: a unitary control section having a plurality of control pistons and a fluid circuit connecting, said control pistons to a source of pneumatic pressure or exhaust and to a source of liquid confined between said power piston and control pistons for securing tandem movement of said pistons comprising, a cast shell-like housing open at one end and along at least one side face and having a wall at its opposite end provided with independent first fluid circuit passages ha'ving ends opening inwardly toward said open end of said housing. one of said passages forming part of a chamber for said confined liquid and communicating with said power piston; machined inserts extending through said wall and having respective machined seating surfaces facing toward said open end ofsaid housing and having respective passages therein connecting said respective seating surfaces to one of said first passages; a plurality of open ended machined cylindrical inserts positioned within said housing with their respective adjacent ends sealingly supported on respective ones of said seating surfaces and communicating with the respective passage therein; respective control pistons r'cciprocably disposed in said cylindrical inserts; a cast metal end closure cap rigidly attached to the open end of said' housing and having respective machined seating surfaces for sealingly sup porting the respective opposite ends of said cylindrical inserts and respective passages opening toward said wall and respectively communicating with said opposite ends of said cylindrical inserts; and machined tubes extending between said wall and said cap and respectively connecting one passage in said cap to said inwardly opening and of the other passage in said'wall and said one of said passages in said cap to the inwardly opening end of said other passage ,in said wall to interconnect respective sides of said control pistons and completesaid fluid circuit.

5. The structure of claim 4 together with a valve positioned in one of said inserts for controlling the flow of fluid through said one passage 'in said wall.

6. The structure of claim 5 together with a movable abutment extending through the other of said inserts into-its respective cylinder for limiting the stroke of said control piston therein.

7. In a power feed mechanism having a power piston movable through an advance and return stroke at a speed determined by the rate of flow of fluid into and out of a fluid chamber at one side of said piston: a valve unit for controlling the said rate of flow, comprising a body having a first passage of a given size and open at all and a second passage in parallel with said first passage; and means to open said second passage only when said fluid is flowing into said chamber whereby said power pistcn wili move through an advance stroke at one speed and through a return stroke at a difl'erent speed.

8. In a hydro-pneumatic mechanism having a power section containing a fluid controlled power piston: a unitary control section in fluid communication with said power section for regulating the movement of said power piston, comprising a cast shell-like housing open at one end and having a wall at its opposite end; a plurality of open ended machined cylinders in said housing in side by side relation; a free piston in each of said cylinders; respective inserts extending through said wall having machined surfaces for sealingly engaging and supporting one end of said cylinders; a cap attached to said open end of said housing and having respective machined surfaces for sealingly engaging and supporting the opposite ends of said cylinders; a plurality of tubes clamped between said wall and cap in parallel relation to said cylinders; and respective fluid passages in said cap for connecting one end of each of said tubes to a respective cylinder; and respective fluid passages in said wall for connecting the other end of one of said tubes and one end of the other respective adjacent cylinder end to said power section andfor connecting the other end of the other of said tubes and its respective adjacent cylinder end to a source of pneumatic pressure adapted to be selectively applied to said power piston or said control pistons to eil'ect desired operation of said mechanism.

9. In a hydro-pneumatic mechanism having a power section containing a power piston and a control section containing a plurality of control pistons: separate cast shell-like housings for each of said sections; an external machined mounting surface on one of said housings; a mating external machined mounting surface on the other of said housings; means for connecting said housings in assembled relation; open ended machined cylinders in each of said housings; a freely re.

ciprocable piston in each of said cylinders; respective members removably mounted at opposite ends of each of said housings, each of said members having a machined surface for sealingly engaging and supporting the adiacent end of said respective cylinders; and fluid passages in said housings and said members adapted to connect one side of each of said pistons to a closed fluid circuit andthe opposite side of each of said pistons to a source of pneumatic pressure adapted to be selectively applied to said power piston or said control pistons to efi'ect desired operation of said mechanism,

10. In a hydro-pneumatic mechanim: a power section for moving a machine tool relative to a work piece: comprising a cast shell-like housing; axially spaced machined surfaces internally of said housing; a machined cylinder frictionally mounted on said machined surfaces; cast members mounted at the opposite ends of said housing having machined surfaces in abutting relation with opposite ends of said cylinder and forming therewith a fluid chamber: a piston reciprocably received within said chamber. said piston being adapted to carry a machine tool; and fluid passages in each of said members through which the opposite sides of said piston are connected to a power fluid circuit and a control fluid circuit.

11. In a hydro-pneumatic mechanism: a power section for moving a machine tool relative to a work piece, comprising an open ended cast shelllike housing; spaced inwardly extending machined surfaces adjacent opposite ends of said housing; a machined cylinder having spaced machined surfaces positioned on said machined surfaces in said housing; cast members at opposite ends of said housing in abutting relation with the oppoite ends of said cylinder and having machined surfaces engaging said machined surfaces in said housing; a power piston reciprocably received within said cylinder; means for rotatably mounting a tool carrying device within said piston; a fluid passage in one of said members for connecting one side of said piston to a closed fluid control circuit; a fluid passage in the other of said members for connecting the other side of said piston to a power fluid circuit; and means associated with said piston and said last mentioned member for preventing rotation of said piston while permitting free reciprocation thereof.

12. A hydro-pneumatic mechanism according to claim 11 wherein said last mentioned means comprises an elongated rod rigidly attached to said piston and reciprocably received within said fluid passage in said last mentioned member.

13. A unitary fabricated control section for a hydro-pneumatic mechanism comprising a recessed cast body having an end wall and open at the other end and along one side, the peripheral marginal side and end edges of said one side and said open end being machined for respective mating engagement with a mounting surface of a machine tool and an end closure cap and saidclosed end having a pair of axially extending, laterally offset mounting bores therethrough spot faced around their inner ends and fluid passages respectively connecting said bores to the interior of said body and at least one of said bores to the marginal end edge formed by said wall and the other of said bores to the exterior of said body; a mounting insert disposed in each of said bores and each having a central, axially extending bore and passage inner ends of said inserts in communication with its respective mounting bore; an annular, axially extending machined support surface of enlarged diameter formed at the inner end of each of said inserts and intersecting a radially directed abutment shoulder disposed in axially spaced relation' from said inner end; a east end closure cap mounted on the open end of said body having cored recesses disposed in respectivec'oaxial alignment with said mounting bores and each having a counterbored annular, machined mounting recess in coaxial relation to the respective mounting surfaces 01' said inserts and fluid passages respectively connecting said recesses to the interior of said body in inverse coaxial alignment with said fluid passages in said wall; respective machine steel cylindrical inserts extending between said mounting surfaces of said inserts and its opposed mounting recess and sealingly engaged therewith; a freely reciprocable piston mounted in each of said cylindrical inserts; and machine steel tubes extending between and sealingly communicatingwith said coaxially aligned passages in said wall and said cap whereby the opposite ends of said cylindrical inserts are structure for placing the 1 cross connected to assure connection of the oppoite ends of said cylindrical inserts to said one bore and to the exterior of said bore.

14. The combination defined in claim 16 wherein the insert in said one bore contains an adjustable bleed passage continuously open to the end of the cylinder mounted thereon and said other insert carries an adjustable abutment element-adapted to predetermine the length of movement or the piston in its associated cylinder.

15. The combination deflned in claim 14, wherein the first mentioned insert also contains a second passage containing a one way valve adapted to permit fluid flow from said end of said cylinder to said one bore.

16. A quill and spindle assembly for a hydropneumatic drill feed mechanism comprising a combined power piston and quill composed of an integral tubular body having an enlarged annular piston portion, oppositely extending reduced diameter tubular end portions and an anti-rotation rod; axially spaced, internal hearing seats formed in one of said tubular end portions, the inner seat at its innermost end terminating in an inwardly directed abutment shoulder; inner and outer bearing elements respectively disposed on said seats and including inner and outer races: an outer sleeve extending between said outer races, an inner sleeve extending between said inner races; a spindle carried by said inner races and having a body portion within said sleeve; a tool chuck of greaterdiameter protruding axially from one end of said body portion and beyond said outer bearing element and forming an abutment shoulder at its juncture with said spindle body portion and a splined section of reduced cross section protruding axially from the other end of said spindle body portion and beyond said inner bearing element and into said tubular body; a bearing. retainer nut threaded on said spindle between said splined section and said inner bearing element and adapted when tightened to clamp said inner bearing races and said inner sleeve between said nut and said abutment shoulder of said spindle; and a retainer nut threaded in the end of said one of said tubular end portions and adapted when tightened to clamp said outer bearing races and said outer sleeve between said last mentioned retainer nut and said inwardly directed abutment shoulder.

11. In a hydro-pneumatic mechanism having a power cylinder, at least one control cylinder, and a fluid circuit connecting said cylinders: a valve for controlling the flow of fluid in saidcircuit comprising, a body having a longitudinally extending central bore and longitudinally spaced ports extending through said body into said central bore; a core in said central bore having one end extending out of said bore and an opposite end normally adjacent one of said spaced [parts] ports; a central recess opening through said one end, and ports connecting the other of said spaced ports in said body with said central recess; and means to move said core longitudinally in said body whereby said one end of said core adjustably covers a portion of said one of said spaced ports to control the flow of fluid therethrough.

18. The combination defined in claim 1'7 together with an end closure element for said bore having a fluid passage; a ball valve adapted to seat on one end of said fluid passage; and resilient means positioned within said recess in said core and engaging said ball to urge said ball against said one-end 01' said fluid close said fluid passage.

19. The combination defined in gether with a longitudinal bore in said core, an axially movable rod extending through said bore in said core, resilient means in said bore for urging said rod against said ball to maintain said ball in its seated position, and separate means for selectively rendering said resilient means ineffective to thereby maintain said rod out of seating contact with said ball.

passage to normally claim 18 tof 20. The combination defined in claim 17 I wherein said valve body includes a flange intermediate said spaced ports and an annular shoulder on said flange for sealingly engaging and supporting one end or said control cylinder between said spaced ports.

21. In a hydro-pneumatic mechanism having a power cylinder, atleast one control cylinder, a power piston and a control piston mounted in the respective cylinders and arranged to move in tandem; means for controlling the stroke 01 said control piston comprising, a cylinder head for said control cylinder; 2. shouldered flange on .said head for sealingly supporting one end of said control cylinder; a reduced section in said head extending away from said cylinder and having a recess opening into said cylinder, said extension also having at least one fluid passage for connecting said recess selectively to a source oi pressure or exhaust; and an abutment rod adjustably extending through said recess into said cylinder for limiting the stroke or said control piston.

22. In ahydro-pneumatic mechanism having an open ended control section containing a plurality of open ended tubular members; a closure cap comprising, a body having a machined marginal surface for engaging said control section at the open end thereof and laterally spaced recesses for sealingly supporting certain of said members; recessed machined surfaces for sealingly supporting others of said members, said recessed machine surfaces being formed around the ends of passages in said cap leading to said spaced recesses.

23. A quill and spindle assembly for a hydro-- pneumatic drill feed mechanism comprising a combined power piston and quill composed 01' an integral tubular body having an enlarged annular piston portion, oppositely extending reduced diameter tubular end portions and an antirotation rod; axially spaced, internal bearing seats formed in one or said tubular end portions, the inner seat at, its innermost end terminating in an inwardly directed abutment shoulder; inner and outer bearing elements respectively disposed on said seats and including inner and outer races; an outer sleeve extending between said outer races; an inner sleeve extending between said inner races; a spindle carried by said inner races and having means providing an abutment, and retaining means on said one of said tubular end portions and said spindle adapted, respectively, when tightened to clamp said outer and inner bearing races and sleeves against the respective abutments on said one of said tubular end portions and said spindle.

24. A power feed mechanism comprising a power cylinder and piston adapted for connection to a machine tool to eilect relative movement of the tool and workpiece; a hydraulic control system 1 for controllin movement of said power piston in both directions and comprising a plurality, of control cylinders and pistons; a control valve operable to alternately connect said power cylinand said control cylinders to a source of pressure and exhaust to alternately egect movement of said power piston and said controlpistons through an advance and retract stroke; a closed liquid circuit having a main passage and a plurality of branch passages control cylinders through which liquid is constrained to how during movement of said power piston, a one-way valve in one of said branch passages adapted to prevent appreciable flow therethrough during the portion of the advance movement of said power piston when flow takes place through said other branches; and means for efl'ectively restricting flow in said main passage to establish a back pressure efl'ective to maintain said one-way valve closed during retracting movement of the control pistons associated with the other of said passages whereby one control piston is held against retracting movement until said other control pistons are fully retracted.

25. A power'leed mechanism having 'a power piston movable in a power cylinder through an advanc and retract stroke; a pair of control pistons movable in respective control cylinders; a closed hydraulic circuit connecting one sid of said power piston and one side of each of said control pistons, said circuit having first and second branches leading to one of said control pistons and a third branch leading to the other ofsaid control pistons; means for selectively connecting the other sides of said power piston and pistons to pressure and exhaust to advance and retract said powerpiston and said control pistons; means restrictin flow in said first of said branches below the flow through said third branch; a check valve in the second of said branches for preventing flow therein from said power piston toward said one of said control pistons; and means in said hydraulic control circuit for maintaining said check valve closed during retracting movement of said other of said pistons and thereafter permitting said check valve to open to permit retraction of said one control piston whereby said control pistons retract sequentially.

26. A power feed mechanism comprising a power piston movable in a power cylinder, a plurality of control pistons movable in respective control cylinders, means for alternately connecting one end of said power cylinder and one end of each of said control cylinders selectively to pressure and exhaust to move said power pistons and said control pistons in advance and retract directions, a closed liquid circuit having parallel fluid the ,mosite end of said power cylinder to the opposite end of each of said control cylinders whereby the rate of movement of said power pision is controlled by the rate of movement of said control pistons, means for controlling the movement of at least one of said control pistons during the advance movement of said power piston to thereby control the rate of advance movement of said power piston, and flow restricting means in said liquid circuit for ejectin sequenbranches connecting I tial retraction of said control pistons.

27. A power feed mechanism having a power piston movable through an advance and retract stroke; a pair of control pistons; a closed hydraulic circuit connecting one side of said power piston and one side of each of said control pistons, said circuit having first and second branches leading to one 0] said control pistons and a third leading therefrom to said branch leading to the other of said control pistons; means for selectively connecting the other side of said power piston and the other side of each of said control pistons to pressure and ea:- haust to advance and retract said power piston and said control pistons; a' check valve in one of said branches for preventing flow therein from I said power piston to said one of said control pistons; and flow restricting means in said hydraulic circuit for maintaining a back pressure on'said check valve to maintain said check 'valve closed during retracting movement of said other of said power pistons to eflect sequential retractionof said control pistons.

28. A power feed mechanism comprising a power member movable in a power chamber, a plurality of control members movable in respective control chambers, means for alternately connecting one end of said power chamber and one end of each of said control chambers selectively to pressure and exhaust to move said power members and said control members in advance and retract directions, a closed liquid circuit hav- 26 ino parallel fluid branches connecting the opposit end of said power chamber to the opposite end of each of said control chambers whereby the rate of movement of said power member is controlled by the rate of movement of said control members, means for controlling the movement of at least one 0! said control members during the advance movement of said power member to thereby control the rate of advance movement of said power member, and flow restricting means in said liquid circuit for effecting sequential retraction of said control members.

References Cited in the flle or this patent or the original patent UNITED STATES PATENTS Number