US1763142A - Hydraulic press - Google Patents

Description

June 10; 17930. w. ERNST HYDRAULIC yPRESS 3 Sheets-Sheet l `Filed Jan. 24, 1929 l Suventvor WMZ/747515Z y 'fafmm' "nil Gttorncgs,

June 10, 1930. W, ERNST 1,763,142

HYDRAULIC PRES S' Filed Jan. 24, 1929 5 Sheets-Sheet 2 l5 L NQ w f l l\ vo a\ QQ Simentor/ June 10, 1930. w, .ERNST 1,763,142

HYDRAULIC PRESS Filed Jan. 24, 1929 3 Sheets-Sheet I5 Patented June 10, f. 1930 v UNITED STATES PAI`EIN'1`-'v OFFICE WALTER ERNST, OFv MOUNT GILEAQD, OHIO, ASSIGNOR T0 HYDRAULIC PRESS MANU- FACTURING COMPANY, OF MOUNT GILEAD, OHIO HYDRULIC rnnss Application led January 24, 1929. Serial No. 334,746.

This invention relates to hydraulic presses which are intended to be operated by fluid supplied under pressure from a variable discharge pump, and more .particularly to that type of press 'which may be set either to automatically perform an indeterminate number of successive pressing operations, or to perform one complete pressing operation, at the end of which the press platen is automatically brought to rest. The present invention embodies certain changes and improvements in the valves and valve operating mechanism shown and described in my application for Letters Patent Serial No. 296,129, ined July a0, 1928.

In the above named application I have described a hydraulic press connected in a hydraulic circuit and arranged to be operated by fluid under pressure delivered by a variable discharge rotary pump also connected in the circuit, the valves and valve operating mechanism controlling the How of fluid in the circuit being so arranged that the pump is dischargeable in one direction only. 'By this arrangement, whereby the pump is dischargeable in one direction only, 'sothat it is unnecessary to shift the heavy pump cross head in order to effect a reversal of the direction of fluid travel in the circuit, a high press operating speed it attainable. The reversal of the direction of fluid travel in the circuit described in the above named application is effected by a special reversing valve, which valve is shifted by pressure responsive means when the pressure in the main press cylinder reaches a predetermined value during the down or pressing stroke of the platen, and is shifted by platen actuated mechanical means when the platen reaches a predetermined point on its return stroke. I have found that, since thisvalveis subjected to very high fluid pressures with a. resultant tendency to leak, it is desirable that the valve be located within the surge tank and submerged in the fluid contained therein.

According to the present invention, I employ an improved and very much simplified reversing valve located in the surge tank for controlling the direction of travel of fluid under high pressure, and a pilot valve connected in an entirely independent lov:r pressure hydraulic circuit and having separate hydraulic connections to the high pressure reversing valve for shifting the latter to reverse the direction of travel of high pressure fluid. The pilot valve controls fluid under a pressure of' approximately only one hundred lpounds per square inch, and may therefore be of light and compact construction and conveniently located on the press framework. The high pressure reversing valve, working' under a pressure of approximately twenty-five hundred pounds per square inch, is necessarily of much heavier construction than the pilot valve, but, since the use of a pilot valvepermits the simplifying of the high pressure reversing valve, and since the latter is located Within the surge tank, the ruggedness of construction necessary for the high pressure valve entails none of the disadvanages of the reversing valve formerly use The #lain object of my invention is to provide i a hydraulic press a high pressure reversing valve connected in the main high pressure hydraulic circuit for reversing the directionof Huid travel therein, which valve is of simple construction, permitting its being located in the surge tank. and a pilot valve connected in an independent low pressure hydraulic circuit and having hydraulic communication with the reversing valve for effecting `shifting of the latter in both direbtions.

Another object of my invention is to provide means for utilizing the pressure in the high pressure circuit for automatically shifting the pilot valve in one direction when the pressure in the highprcssure circuit builds up to a predetermined value during the pressing stroke of the platen, and mechanical platen-actuated means for returning the pilot valve to its initial position when the platen reaches a predetermined point on its return stroke. y

Among the several other objects of my invention is the provision of means whereby a hydraulic press equipped with valves ofthe character described may be arranged to opcrate either. automatically or semi-automat` ically.

With these and other objects in view, the nature of which will more fully appear, the invention will be understood from a reading of the following description, the appende claims, and the several views illustrated in the drawings, in which:

Figure 1 is a front elevation of a hydraulic press showing some essential operating parts embodying my invention;

Figure 2 is a partial side elevation taken at right angles to Figure 1, drawn on .an enlarged scale and showing some parts in section' Figure 3 is a diagrammatic View of the high pressure and the low pressure circuits; t

Figure 4 is a central vertical sectional view of a main pressing cylinder and a surge shifting valve mounted thereon;

Figure 5 is a longitudinal sectional View of a pilot valve;

Figure 6 is a longitudinal sectional view of a reversing valve;

Figure 7 is a detail sectional view end of a piston valve;

Figure 8 is a detail view of the upper end of a pilot valve actuating rod and associated parts;

Figure 9 is a head, and

Figure 10 is a fragmentary sectional View taken on the line l0-10 of Figure 5.

Heretoiore, in connection with automatic presses of the character herein described, it has been usual to employ a variable discharge reversible ump of the type described iny U. S. Letters Fatent No. 1,250,170, of December 18, 1917, granted to Hele-Shaw et al. Pumps of this typeare provided with a cross head, the shifting of which reverses the flow of the fluid in the hydraulic circuit, the reversals producing the reciprocatory motion of the press platen.

While the construction of this type of pump is now well known to those skilled in the art, for the sake of clearness attention is of one plan view of a pump cross called to the fact that in such pumps there is usually provided a spring adapted to yieldingly hold the pump cross head in a osition permitting the pump to deliver its ull discharge, there being also provided either mechanica] or pressure. operated means adapted to more said cross head against the pressure of said spring, thereby progressively reducing the discharge of the pump to zero, and then progressively increasing the discharge of the pump in the opposite direction. Where the press used is large, and the pump cross head is correspondingly large, the cross head has an inertia sufficient to oppose the shifting thereof to an appreciable degree, and to thereby cause a considerable time lag to occur between the strokes of the platen, which naturally is -objectionable since it slows down the operating speed of the press. In the present invention, the pump is arranged to discharge in one direction only,` and by providing means whereby the fluid discharged by the pump may be directed alternately to the pressing cylinders and to the push back cylinders operating the press platen, it is possible to attain a high operating speed with a large press.

When operating a large hydraulic press, it is of course essential that the discharge of the pump be reduced as the press platen nears the ends of the up and the down strokes, since a sudden reversal of flow of the fluid under pressure when the pump is delivering its full discharge would result in a shock or water hammer in the hydraulic system, such shock being injurious to the various associ ated parts. Accordiner to the present invention, means are provided for reducino the rate of discharge of the pump as the p aten nears the ends ofthe up and the down strokes, thus preventing the occurrence of such shocks. l

It is to be understood that, in the description which is to follow, the term automatic operation means that kind of operation in which thereciprocatory platen continuously performs an indeterminate number of pressing operations, and the terni semi-automatic operation means that kind of operation in which the platen performs one complete pressing cycle, and is then brought to rest in itsl uppermost position.

The invention may be embodied in various types of hydraulic presses, but in the accompanying drawings it is illustrated in connection with a press of the four column downward pressure type. Referring to the drawings, there is shown a hydraulic press A, having a base B, a `stationary table C, a press head D connected to said table by four strain rods E, and a reciprocatory platen F guided on the'strain rods E in the usual manner.

It is to be understood that the present invention includes two entirely se arate hydraulic circuits, one being a higli pressure ress operating circuit and the other being a ow pressure pilot circuit. The low pressure circuit is use to eect the shifting of a reversing valve in the high pressure circuit for producing resultant reciprocatory movements of the press platen. .'These two circuits will be first outlined and the various valves and valve operating mechanisms included in .each of the circuits will be subsequently described in detail.

With reference to the high pressure circuit, a variable discharge pump 1 of the type above referred to is connected to a surge tank 2 by means of the suction pipe 3, as shown in Figure 3, and supplies fluid under high pressure to said circuit. The discharge of the pump is directed through a pipe line 4 las etA

which is connected to the reversing valve 5.

The valve 5 also has connected to it the pipe line 6, which leads to booster cylinders 7 and to one side of a surge shifting valve 8 located in the surge tank 2, and a pipe line 9 which leads to push back or platen returning cylinders 10 and to the other side of the sur e shifting valve 8. The reversingvalve is ocated within the surge tank 2 and is provided with exhaust openings communicatmg with the surge tank.

The construction and the operation of the reversing valve 5 will be hereinafter described in detail, but for the sake of clearness it Will, for the present, be sufficient to say that the valve is adapted to be set in either of two positions, in the irst of which positions the pipe line 4 is placed in communication with the ,pipe line 6, and the" pipe line 9 with the surge tank by means of one of the aforementioned exhaust openin s, andv in the second of which positions the plpe line 4 is placed in communication with the''pipe line 9, and the pipe line 6 with the surge tank by the other of the aforementioned Vexhaust openings. 1, ff-1 The low pressure pilot circuitiincl'udes-a pipe line 11 which communicates i with the surge tank, a low pressure pump 12'arranged to receive its intake from the pipe line 11, and a low pressure discharge pipe line 13 connected 4to the pump and to a pilot valve 14. A pipe line 15 connected to the pilot valve and to the surge tank 2 affords communication therebetween, and it will thus be seen that the pipe line 11, the pump 12, the pipe line 13, the pilot valve 14, the pipe line 15, and the surge tank 2 comprise the entire low ressure hydraulic pilot circuit. Separate p1pe lines 16 and 17 connect the pilot valve to a ressure responsive valve actuating device associated with the reversing valve, but it is to be noted. that the pipe lines 16 and 17 form no part of the low pressure circuit. The pilot valve is so arranged that, upon being shifted in one direction, iuid under pressure from the lovtr pressure pilot circuit will be introduced through.

the pipe 16 into one side of the pressure responsive valve actuating means Gr to shift the reversing valve in one direction, and when the pilot valve is shifted in the opposite di- 'rection fluid under pressure from the low pressure pilot circuit will be introduced through the pipe line 17 into thel opposite side of the pressure responsive valve actuating means G and willmove the reversing valve in the opposite direction.

The surge shifting valve 8 is provided with a valve casing 18 having a valve chamber 19 which communicates with the surge tank 2 by means of a port 20, andwith the main cylinder 21 of the press by means of a port 22. Slidably mounted in the chamber 19 is a balanced piston valve 23, said valve being provided at one of its ends'with a tail rod 24, the

second tail rod 27 `which extends through a lchamber 28 into a bore 29 in a casin 30 attached to the casing 18, and into a c amber 31 in said casing 30, the chamber 31 communicatingat its outer end with the pipe line 9. It may be noted that, when the piston valve 23 -is in the position shown in the drawing, the main cylinder 21 communicates With'the surge tank 2 by means of the ort 22, the chamber 19, and the port 20, but, w en the piston valve is caused to be shifted to the left in a manner to be hereinafter described, the cylinder 21 will communicate with the pipe line 6 by means of the port 22, the chamber 19, the passage 26, andthe bore 25.

` Mounted on the top of the valve casing 18 and adapted to communicate with the chamvber28 is a check valve 32, which comprises a by a spring 37, the vtension of which spring may be adjusted by means of a threaded plug 38 for a purpose hereinafter specified. It is to be noted that, when the piston valve 23 is moved tothe left in the plane of the drawing,

fluid contained in the chamber 28 will be expelled lthrough the check valve 32 into the surge tank 2, but that no uid will enter the chamber 28 through said check valve at any time.

Mounted on the bottom of the casing is a second check valve 39 adapted to communicate with the chamber 28 by means of a port 40 and with the surge tank 2 byf'means of a port 41. It is to. be noted that, thou h no iiuid will be discharged from the c amber 28 through the valve 39 and into the surge tank 2, a valve ball 42 is kept seated by gravity, and by the pressure in the chamber 28, so that when the piston valve 23 moves to the right in the plane of the drawing the ball .42 will be lifted from its seat by the suction created in the chamber 28, thus allowin iiuid to ow from the surge tank 2 throug the ports 41 and 40 into the chamber 28.

With more particular reference to the reversing valve 5, there is shown in Figure 6 a valve casing 42a having a central chamber 43 and a piston valve 44 slidable longitudinally in the chamber. In order to facilitate the connecting of the reversing valve to the pipe lines 6 and 9, there are provided detachable plates 45 and 46 bolted to the valve casing 42, shoulders 47 on said plates fitting within counter bores 48 in the valve casing, and clamping packing 49 in said bores, thus forming a pressure tight joint between the casing and the plates. The plates are provided with threaded bores which receive the ends of the pipes 9 and 6, and these bores registerrespecvalve casing 42a. A similar plate 52 is bolted to the valve casing midway between the ports 50 and 51 and is provided with an opening 53 which communicates with the chamber 43, and in which opening the pipe line 4 is connected. It will be apparent that, when the piston valve 44 is in the position shown in Figure 6, the pipe line 4 will communicate with the pipe line 6 by means of the opening or port 53, the valve chamber 43, and the port 51. lVhen the pistonvalve is moved to the left the pipe line 4 will be placed in communication with the pipe line 9 by means of the opening 53, the valve chamber 43, and the port 50.

When the valve is in the position shown in Figure 6, and the pipe line 4 is in communication with the pipe line 6, it is necessary that the pipe line 9 be placed in com'- munication with the surge tank. To this end, I provide the valve casing 42 with an annular recess 54 which is in alignmentwit-h and formed to communicate with the port 50, and I further provide the piston valve with a transversely disposed opening 55 extending through theend portion of said valve adjacent the recess 54, and a port 56 formed in the valve and extending from thetransverse opening 55 to the adjacent outer end of the piston valve. The outer end of the opening 56 is enlarged and threaded to receive a removable plug 56u having a central-opening 56b extending longitudinally therethrough to register with the opening 56. It will be seen that fluid in the pipe line 9 will enter the annular recess 54, then pass into the transverse opening 55, and then out through the port 56 and the opening in the plug and into the surge tank, the end of the piston valve 44 being constantly exposed to the Huid in the surge tank. When the piston valve is moved to the left in the plane of the drawing, the transverse opening 55 `will be moved away from the recess 54 and communication between the pipe line 9 and the surge tank will be thereby cut off. It is now necessary that, with the valve in this new position, the pipe line 6 be placed in communication with the surge tank. For accomplishing this purpose I provide the valve casing with a chamber 57 located to the right of 1the piston valve and provide said chamber?? with a plurality of outlets 58 extending through the valve casing and communicatingr with the surge tank. lVhen the pistoni' valve has moved to the left, the right hand end of the valve will move to the left of an annular recess 59 which is formed in the valve casing and which communicates with the port 51, and the pipe line 6 will be placed-in communication with the port 51, the valve chamber 43, the chamber 57, and the openings 58.

For shifting the valve 44 in either direction, I provide the pressure responsive valve actuating means G located at the outer end of the reversing'valve. This valve actuating means includes a pressure chamber 60 formed in the outer end of the valvecasing 42a, a port 61 communicating with the inner end of the chamber 60 and with the pipe line 16, a port 62 communicating with the outer end of the chamber 60 and with the pipe line 17 a piston rod or stem 63 extending from the valve 44 and into the chamber 60, and a piston 64 fixed to the outer end of the rod 63 and mounted for reciprocatory movements in the chamber 60. It is apparent that, when fluid under pressure is admitted from the low pressure pilot circuit through the pipe line 17 and into the outer end of the chamber 60, the piston 64 will be moved to the left as Viewed in the plane of the drawing, and the valve 44 will be shifted to place the pipe line 4 in communication with the pipe line 9, and the pipe line 6 in communication with the surge tank. In a similar manner, when fluid under pressure is admitted from' the low pressure 'pilot circuit through the pipe line 16'and into the inner end of the chamber 60, the piston 64 and the valve 44 will be returned to the position shown in Figure 6, thereby placing the pipe line 4 in communication with the pipe line 6, and the pipe line 9 in -communication with the surge tank.

The pilot valve 14 is used to direct Huid from the low pressure pilot circuit lirst into the pipe line 16 to shift the piston valve 44 to the right as viewed in Figure 6, and then to introduce Huid under pressure from the low pressure pilot circuit into the pipe line 17 to shift the piston valve 44 to the left. The pilot valve includes a valve casing 65 formed with a valve chamber 66, which chamber communicates with the pipe line 13 by means of a port 67 formed in the casing. The chamber 66 is also arranged to communicate with the pipe line 16 by means of an outlet port 68 and to communicate with the pipe line 17 by means of an outlet port 69. Slidably mounted in the bore forming the chamber 66 is a piston valve 7 O having a stem 71 extending from one end of the valve through packing 7 2 held in place by a gland nut 73 threadably mounted in an end cap 74 secured to the outer end of the valve casing. The stem 71 extends through and somewhat beyond the gland nut 73 and is provided with a flange 75 located within the valve chamber and adapted to abut an inwardly extending flange 76 on the end cap 74, thus limiting the travel of the valve to the right. "When the valve 70 is in the position shown in the drawings, that is, in its extreme right hand position, the pipe line 13, receiving fluid from the low pressure pump 12, will communicate with the pipe line 17 by means of the port 67, the valve chamber 66, and the port 69, whereas, when the valve 70 is moved to the left, the

pipe line 13 will communicate with the pipe I closed position,

17 may be able to move the piston 64 of the reversing valve. To this end I provide the pilot valve with a port 77 which communi- Cates with the valve chamber 66 and with the pipe line 15, which pipe line is in constant communication with the surge tank, and a cored passage 78 formed in the valve casing to connect the end portions of the chamber 66 located on opposite sides of the.

piston valve 70. When the valve 70 is in the position shown in Figure 5, the pipe line 16 will communicate with the pipe line 15 by means of the port 68, the valve chamber 66, the cored passage 78, and the port 77. When the piston valve 70 is moved to the left in the plane of the drawing, the pipe line 17 will communicate with the pipe line 15 by means of the port 69, the valve chamber 66, and the port 77.

As stated above, the pipe lines 16 and 17 leading from the pilot valve to the chamber 60 in the reversing valve do not form a pa'rt of the low pressure circuit, and, after fluid under pressure acting through either of'these pipe lines has acted to shift the piston 64, there will be no further flow of fluid through either of said pipelines. Since the low pres- I sure pump delivers a continuous discharge, it is necessary that means be provided for directing the discharge of the pump into the surge tankduring intervals between movements of the piston 64. For accomplishing this purpose the pilot valve 14 is provided with a reliefl valve H. This relief valve includes a plunger 79 slidably mounted in a sleeve 80 rigidly mounted in a bore 81 formed in the valve casing and adapted to communicate with the port 67 and the pipe line 13 by means of' a port 82. The sleeve 81 is provided with a slot 83 extending through the wall of the sleeve and communicating with a port 84 formed in the valve casing to communicate with the valve chamber 66 at the inner end thereof. The plungcrr79 is provided at one of its ends with a flange 85 adapted to abut an inwardly extending flange 86 formed in the valve casing and to thus limit the movement of' the plunger in one direction. The valve casing 65 is further provided with a spring chamber 87 concentrically arranged with the plunger 79, and positioned within this spring chamber is a coiled spring 88 interposed between the end of the plunger 79 and a threaded plug 89 screw threaded into the spring chamber, the spring serving to urge the plunger 79to a in which position the inner the hand end portion of the plunger extends past the slot 83. A hollow nut 90 is screw threaded on the' plug 89 for covering the latter, and also serves as a lock nut to retain the plug 89 in adjusted position. The port 84 communiwith the spring chamber 87 bv means of a cored passage 91. When the piston valve is moved to the lett, fluid will be admitted from the low pressure pilot circuit through the pipe line 13, the port 67, the valve chamber 66, the port 68, and the pipe line 16 into the inner end of the chamber 60 in the reversing valve,thereby moving the piston 64 to the right, as viewed in Figure 6. When the piston 64 has been moved to itsextreme right hand position so that there can be no further fiow of fluid through the pipe line 16, the pressure in the low pressure pilot circuit will build up and will move the relief valve plunger 79 against the pressure exerted by the spring 88 until the innerend of the plunger has moved to place the port 82 in communication with the port 84 by means of the slot 83, at which time the low pressure fluid will be discharged from the pipe line 13 through the ports 67 and 82, the slot 83, the port 84, the cored passage 78, the port 77, and the pipe line 15 into the surge tank. It is to be noted that the spring chamber 87 is in constant communication with the surge tank by means of the cored passage 91, the port 84, the cored passage 78, the port 77, and the pipe line 15, so that the static pressure of the fluid in the surge tank acts upon the outer end of the plunger 79 and thus aids the spring 88 to urge the plunger to its closed position.

Rigidly fixed to the valve casing 65 is a separate casing 92, which casing is provided with a chamber 93 and with inwardly extending flanges 94 and 95 concentrically aligned with the valve chamber 66 ofthe pilot valve. Slidably mounted in the casing 92 is a'valve actuating plunger 96. The plunger 96 is provided with a stem 97, which projects into the valve chamber 66 of the pilot valve, and a flange 98 on the plunger is adapted to seat in a recess 99 formed' in a bushing 100 mounted in adjacent and concentric counter bores 101 and 102 in the casings 92 andv65, thus limiting the movement of the plunger 96 in one direction.

The plunger 96 is also provi-ded with another stem 103 extending through packing 104 and a gland nut 105 screw threaded into an opening 106 in the end of the casing 92. The outer end portion of the stem 103 is threaded to receive a hand wheel 107, and interposed between the hand wheel and the gland nut105 is a coil spring 108 and a spring seat 10,9. illhe hand wheel 107 is screwed on the stem`108 to place the spring under compression so that wheel, the stein 103, and the plunger 96 will be constantly urged outwardly. A V

second and smaller hand wheel 110 is screw threaded on the end of the stem and drawn up tight against the hand wheel 107 for locking the latter and retaining it against accidental displacement from its adjusted position.

The plunger 96 is of slightly greater diameter than the stem 103 and forms therewith a resultant shoulder 111, which shoulder is at all times disposed within the chamber 93. Connected to the casing 92 and arranged to communicate with the chamber 93 therein is a pipe 112 which is also connected to the pipe line 6, so that the chamber 92 is in constant communication with the pipe line 6. It will be apparent that, when the piston valve 70 of the pilot valve is in. its left hand position, a building up of pressure in the pipe line 6 will result in a corresponding building up of pressure in the chamber 93, and when a predetermined pressure has been reached, which pressure is determined by the amount of pressure exerted by the spring 108, the plunger 96 will be moved to the right in the plane of the drawing until the stem 97 carried by the plunger engages the piston valve 70 and moves it to the right, that is, moves it into the position shown in Figure 5.

For moving the piston valve 70 to the left as viewed in Figure 5, I provide mechanical platen actuated means adapted to engage the end of the stem 71. As will be hereinafter described, when this movement takes place, the pressure in the pipe line 6 and in the chamber 93 will have decreased so that the spring 108 will have moved the stem 103 and the plunger 97 to the left, thus permitting the piston valve 70 to be moved to the left by the stem 71.

Referring to Figure 1, there is shown a vertically disposed operating rod 113 slidably mounted in lugs 114 and 115 on the stationary table C and the press head D respectively,

the downward movement of said rod being limited by a collar 115 adj ustably fixed to the `\rod. The rod 113 is constantly urged to its vrss lowermost position by gravity, andalso by means of a coiled spring 116 mounted on the rod between the lug 115 and a collar 117 also on said rod. A boss 118 fixed to the platen F is arranged .to slide freely on the rod 113. Adju-stably mounted on the rod 113 is a collar 119 which is adapted to be engaged by the boss 118 when the platen has reached a predetermined point in its upward travel, the rod 113 being thereby lifted. The upper end of the ro'd 113 is provided withan inwardly extending recess 120, and, adjacent the eXtreme upper end portion of the rod, with a pair of oppositely disposed slots 121. Slidably mounted in the recess 120 is a rod 122 provided with a pin 123 which extends through and is rigidly attached to the rod, and has its opposite end portions projecting through the slots 121. A coil spring 124 is located in the recess 120, and is disposed between the bottom of the recess and the inner end Aof the rod 122, the spring constantly urging the rod to its uppermost position, in which position the pin 123 contacts with the upper end walls of the slots 121. A bell crank lever 125 is pivotally connected to the press head D as at 126. The arm 127 of the bell crank lever is pivotally connected to a head 128 on the rod 122 as at 129. The other arm 130 of said lever is provided with a rounded head 131 adapted to engage the stem 71 of the pilot valve and to move it inwardly when the rod 113 is lifted. The spring 124 urges the rod 122 to its uppermost position at all times, and serves as a. cushion for relieving the pilot valve. of any undue shock which might otherwise occur if the connections between the operating rod and the valve stem were rigid.

Attention is called to the fact that, although the piston valve of the pilot valve has no permanent connection either to the stem 97 or to the bell crank leve'r 125, the piston valve is disposed in a horizontal plane and will be retained in either of its positions by the frictional contact of the packing 72 with the stem 71, until said piston valve is positively shiftedin the manner described above.

A manually operable lever 132 is pivotally mounted on the base B as at 133, and one arm 134 of said lever is provided with a rounded head 135 adapted to engage the lower face of a collar 136 fixedly mounted on the operating rod 113 and to lift said rod when the lever is swung in a clockwise direction as viewed in Figure 1. A coil spring 137 interposed between the base B and the arm 134 of the lever tends to cause a lug 138 on said lever to abut a lug 139 on the base, thereby normally maintaining the lever in the position shown in Figure 1. It is to be noted that, when the rod 113 is caused to perform a reciprocatory motion during automatic operation of the press, the collar 136 will move to mounted in lugs 141 and 142 on the stationary table C and the press head D respectively. The downward movement of said rod is limited by collars 143 and 144 ixedly attached to the rod. The operating rod 140 is constantly urged to its lowermost position -by gravity and by means of a coil spring 145 mounted on said rod and interposed between the lug 142 and a collar 146 on the rod. A boss 147 on the platen is arranged to slide freely on the operating rod 140. Adj ustably attached to the rod 140 is a collar 148 which is adapted to be engaged by the boss 147 when the platen has reached a predetermined point in its upward travel, the rod 140 being thereby lifted.

Rigidl attached to the base B directly below the ug 141 is a bracket 149 to which a bell crank lever 150 is pivoted as at 151. A link 152 is pivoted to the operating rod 140 at 153 and to the bell crank lever 150 at 154.

A link 155 disposed at right angles to the operating rod 140 is pivotally connected to the bell crank lever at 156. A lever 157 pivotally mounted at 158 on a bracket 159 carried by the pump, has one of its ends pivotally connected at 160 to the link 155. The other end of the lever 127y is provided with rounded head 161 adapted to engage a cross head 162 on lthe pump 1, whereby a clockwise movement of the lever 157 will cause the pump cross head to be pushed towards the center of the pump, thus decreasing the discharge of thepump in a manner well known to those skilled in the art. As stated above, pumps of this type are providedwith a. spring for returning the cross head to a. position permitting full discharge ofthe pump when the externally applied force, such as the pressure exerted on the cross head by the lever 157, is removed.

Operation I it is desired that the press operate under full automatic control, the collar 119 is adjusted to a position on the operating rod 113, in which position said collar will be engaged by the boss 118 on the platen as the platen approaches the end of its upward or return stroke, and the motor driving the pump will then be started.

Assuming that this adjustment of the collar 119 has been made, that the motor driving the pump has been started, and that the reciprocatory platen is traveling downward, the piston valve 44 of the reversing valve 5 will be in the position shown in Figure 6 and the piston valve 23 ofthe surge shifting valve 3 will be in the position shown in Figure 4, and the operation of the various parts comprising the automatic control mechanism will be as follows:

The pump 1 is set to deliver its Jfull discharge of fluid under pressure through the pipe line 4 into the reversing valve 5, the fluid passing from the pipe line 4 through the port 53, the valve chamber 43, the port 51, and the pipe line 6, and into the booster cylinders 7, the fluidfpressurc thereby exerted in said booster cylinders causing the platen to move downwardly. -During this part'of the down stroke of the platen, fluid from the surge tank 2 will flow through the port 20, the valve chamber 19, and the port 22 into the main cylinder 21. lVhile the down stroke of the platen isbeing performed the fluid which entered the push back cylinders 10. during the preceding up stroke must escape from said cylinders into lthe surge tank. This is accomplished by means ofthe pipe line 9, the

port 50, and the openings 55 and 56 in the piston valve 44.

Vhen the platen encounters resistance to its downward movement, the fluid pressure in the pipelines 4 and 6 will build up until it reaches a predetermined value, at which time said' pressure, acting on the tail rod 24 of the surge shifting valveS, will cause the piston valve 23 to moveto the left from the position shown in Figure 4, thereby expelling the fluid contained in the chamber 28 through the ports 35 and 34 of the check valve 32. It is to be noted that, by adjusting the plug 38 to vary the pressure exerted on the ball 36 by the spring 37, the fluid pressure in the pipe line 6 lnecessary to move the piston valve to the lett may be varied at will.

After the piston valve 23 has been moved to the left as described above, the valve chamber 19 will be shut off from communication with the port 2() by the right hand end portion ofsaid valve, and at the same time said valve chamber 19 will be placed in communication with the pipe line 6 by means of the passage 26 and the bore 25, which bore has been vacated by the tail rod 24. The main c linder 21 now receives fluid under pressure rom the valve chamber 19 through the port 22. The platen continues its downward movement until the pressure building up in the circuit acts to move the pump cross head inwardly. against the pressure of the cross head spring, thus dev creasingv the rate of discharge from said pump and preventing the occurrence of shocks which might otherwise take place when the flow of fluid is reversed to start the platen on its return stroke. As has been heretofore stated, the chamber 93 of the ilot valve 14 is in constant communication wit the pipe line 6 by means of th'e pipe 112, so that,

as the fluid pressure builds up in the main and booster cylinders, the pressure will increase correspondingly in said chamber until a predetermined pressure has been reached, at which time the plunger 96 will be moved to the right by the pressure in said chamber and against the force of the spring 108.

It is to be understood that, while the platen has been descending to perform its pressing stroke, the piston valve 70 has been in a position to the left of that shown in Figure 5, so that the pipe line 13 of the low pressure circuit has been in communication with the ipe line 16. Since the piston valve 44 has been stationary during this pressing stroke of the platen, fluid from the low pressure circuit has not been. flowing through the pipe line 16, but the discharge of the pump 12 has been by-passed by means of the relief valve,

and returned to the surge tank in the manner described above. lVhen the plunger 96 of the pilot valve 14 is moved to the right as viewed lin Figure 5, the stem 97 will contact the piston valve 70 and move said valve to the position shown in Figi ure 5. Fluid from the low pressure circuit will now pass through the pipe 13 and the pipe 17 into the right hand end of the pressure chamber of the reversing valve 5 and will force the piston 64 to the left as viewed in Figure 6, thus shifting the piston valve 44 to place the port 53 in communication with the pipe line 9. In this new position of the piston valve 44, the pipe line 4 will communicate with the push back cylinders 10 by means of the port 53, the valve chamber 43, the port 50, and the pipe line 9, and the pipe line 6 will communicate with the chamber 57 so that the booster cylinders will communicate with the surge tank by means of the pipe line 6, the ort 51, the chamber 57, and the openings 58. Fluid under pressure in the pipe line 9 and in the chamber 31 of the surge shifting valve will now act on the tail rod 27 causing the piston valve 23 to be moved to the right, or, in other words, to the position shown in Figure 4. lVliile the piston valve is moving to the right, fluid from the surge tank 32 will enter the chamber 28 through the check valve 39, as hereinbefore described. The fluid under pressure entering the push back cylinders l0 from the pipe line 9 causes the platen to move upwardly, and the fluid in the main cylinder 21 will be expelled therefrom into the surge tank through the port 22, the valve chamber 19, and the port 20. During the upward movement of the platen, Huid will be expelled from the booster cylinders through the pipe line G, the port 51, the valve chamber 43, the chamber .'37, the openings 58, and into the surge tank 2. It is to be noted that, since the pressure in the pipe line 4 is less at this time than it was at the time the platen met resistance to its downward travel, the spring on the plump cross head will return said cross head to a position permitting maximum discharge b y the pump, thereby rapidly returning the platen to its uppermost position.

lVhen the platen reaches a predetermined point in its upward travel, the boss 147 will strike the collar 148 on the operating rod 140, thereby lifting said rod and causing` the lever 157 to be swung in a eounterclockwise direction, as viewed in Figure 2, by means of the link 152, the bell crank lever 150, and the link By this movement ot' the lever 157, the head 161 of the lever forces the cross head 162 of the pump inwardly against the force of the pump cross head spring', thereby reducing the rate of discharge from the pump preparatory to a reversal of the direction of travel of the press platen for the purpose stated above.

71 of the pilot valve inwardly and shifting the piston valve thereof to the left as viewed in Figure 5,

In this position of the piston valve 70, fluid will pass from the low pressure circuit through the pipe line 13, the valve chamber 66 ot' the pilot valve, and the pipe line 16 into the pressure chamber 60 of the reversing valve, thereby moving the piston 64 to the right as viewed in Figure 6 and shifting the piston valve 44 to the position shown in Figure (3. With the valve 44 in this position, the platen will begin another pressing stroke which will be performed in the same manner as the one already described, and obviously the press will continue to operate in this manner as long as the motor driving the pump 1s running.

It it is desired to operate the press semiautomatically, in other words, in such a way that the platen will perform one pressing operation and then return to its uppermost position and stop, the collar 119 on the operating rod 113 is loosened and moved to a position in which it will not be engaged by the boss 118. Assuming that the laten is on its downward stroke, the completion ofthe downward stroke and the start of the return stroke will be executed in the same manner as that already described. Vhen the boss 147 strikes the collar 148 on the return stroke of the platen, the rod 140 will be lifted and the pump cross head will be moved inwardly until the cross head has reached a point at which the discharge of the pump is zero, and the platen will then come to rest.

To cause the platen to perform another pressing operation, the manually operable control lever 132 is swung to the right, thereby raising the rod 113 and moving the stem 71 of the pilot valve inwardly. rlhis results in shifting the piston valve 44 of the reversl ing valve to the position shown in Figure 6,

thlus placing the pipe line 4 in communication with the pipeline 6 and with the booster cylinders. It may be noted that, although the valves 5 and 8 are now in a position to allow fluid under pressure to produce a downward movement of the platen, the pump is at this time not delivering fluid under pressure to produce a downward stroke, as its discharge is zero. However, since the main cvlinder 21 communicates with the surge tankbv means of the port 22, the chamber 19, anld the port 20, the push back cylinders 10 communicate with the surge tank by means of the pipe line 9, the port 51, the openings 55 and .56 in the piston valve 44, and the booster cylinders 7 communicate with the surge tank by means of the pipe line-6, the valve 5, the pump 1, and the pipe line 3, there is no fluid pressure tending to hold the platen up. The weight of the platen itself will cause the platen to coast downwardly until the operating rod 140 has been lowered and the pump cross head 162 thereby allowed to bemoved by the cross head spring,I whereupon the pump will start to discharge'and the operation will proceed in the manner already described.

Although l have illustrated a press provided with a platen especially adapted for performing compressing operations, it is to be understood tnat the invention described herein may be embodied in presses used for punching, forging, shearing, or other like purposes and that the term platen7 is intended to cover any tool, die, or other appliance with which a press embodying my invention might be provided. Other modifications in construction and arrangement of.

parts may be also made without departing from the scope of my invention.

I claim:

l. The combination with a hydraulic press including a reciprocatory platen; of a pump dischargeable in one direction only; means forming with the press and with the pump a high pressure hydraulic press-operating circuit; a reversing valve operatively connected in said circuit; a low pressure hydraulic pilot circuit; a pilot valve operatively connected in said low pressure circuit; pressure responsive actuating means associated with said reversing valve; hydraulic connections between the pilot valve and said pressure responsive actuating means for admitting fluid from said low pressure circuit to said actuating means to shift the reversing valve when the pilot valve is shifted; and means for shift-ing the pilot valve when the platen approaches the limit of one of its reciprocatory movements.

2. The combination with a hydraulic press including a reciprocatory platen; of a pump p dischargeable in one direction only; means forming with the press and with the pump a.

high pressure hydraulic press operating circuit; a reversing valve operatively connected in said circuit; a lo'w pressure hydraulic pilot circuit; a pilot valve operatively connected in said low pressure circuit; pressure responsive actuating means associated with said reversing valve; hydraulic connections, between the pilot valve and said pressure responsive actuating means for admitting fluid from said low pressure circuit to said actuating means to shift the reversing valve when the pilot valve is shifted; and means for automatically shifting the pilot valve when the platen approaches the limit of one of its reciprocatory movements.

3. rIlhe combination with a hydraulic press including a reciprocatory platen; of a pump dischargeable in one direction only; means forming with the press and with the pump a high pressure hydraulic press-operating circuit; a reversing valve operatively connected in said circuit; a low pressure hydraulic pilot circuit; a pilot valve operatively connected in said low pressure circuit; pressure responsive actuating means associated with said reversing valve; hydraulic connections between the pilot valve and said pressure responsive actuating. means for admit-ting fluidfrom said low ressure circuit to said actuating means to s ift the reversing valve when the pilot valveis shifted; .means for automatically shifting the pilot valve whenv the platen approaches the limit of its press ing stroke; and other means for automatically shifting the pilot valve in the opposite direction when the platen approaches the end of its return stroke. i

4. The combination with a hydraulic press including a .reciprocatory platen; of a pump v dischargeable in one direction only; means forming with the press and with the pump a high pressure hydraulic press-operating circuit; a reversing valve operatively connected in said circuit; a low pressure hydraulic pilot circuit; a pilot valve operativelyvconnected in said low pressure circuit; pressure responsive actuating means associated with said reversing valve; hydraulic connections between thek pilot valve andsaid pressure responsive actuating means for admitting fluid from said low pressure circuit to said actuating means to shift the reversing valve when the pilot valve is shifted; and pressure responsive means associated with said pilot valve and having hydraulic communication with said high pressure circuit, said pressure responsive means being operable for shifting the pilot valve in one direction upon the attainment of a predetermined pressure in said circuit when the plateny approaches the f end of its pressing stroke.

5. The combination with a hydraulic press including a reciprocatory platen; of a pump dischargeable in one direction only; meansforming with the ress and with the1 pump a high pressure hy raulic press-operating circuit; a reversing valve operatively .connected in said circuit; a low pressure hydraulic pilot circuit; a` pilot valve operatively connected in said low pressure circuit; pressure responsive actuating means assoc1ated with said reversing valve; hydraulic connections between the pilot valve and said pressure responsive actuating. means for admitting fluid from said low pressure circuit to said actuating means to shift the reversing valve when thepilot valve is shifted; pressure responsive means associated with said pilot valve and having hydraulic .communication with said high pressure circuit, said pressure responsive means being operable for shifting the pilot valve in one direction upon the attain` ment of a predetermined pressure in said circuit when the platen approaches the end of its pressing stroke; and platen actuated means for automatically shifting the pilot of its return stroke.

6. The combination with a hydraulic press including a reciprocatory platen, a main cylinder, and a platen returning c linder; of a pump dischargeable in one direction only; means forming with the pum and with said cylinders a high pressure hy raulic press-operating circuit; a reversing valve connected in said circuit for reversing the direction of iluid travel therein to reci rocate the platen, said valve including a va ve casing formed with a valve chamber, a port communicating with said pump and with said valve chamber, a port communicating with said main cylinder and with said valve chamber, a port communicatin with said platen returning cylinder and wit said valve chamber, and means mounted for movement in said valve chamber for placing said ump in communication with said main cylin er when said means are moved in one direction, and for lacing said pump in communication with said) platen returning cylinder when said means are moved in the opposite direction; pressure responsive actuating means associated with said movable means for moving the latter in opposite directions; a low pressure pilot circuit; a pilot valve operatively connected in said circuit; hydraulic connections between the pilot valve and said ressure responsive actuating means for a mitting fluid under pressure from said low pressure circuit to said actuating means to move said movable means when the ilot valve is shifted; and means for shiftmg the pilot valve when the platen approaches the end of one of its reciprocatory movements.

7. The combination with a hydraulic press including a reciprocatory platen, a main cylinder, and a platen returning cylinder; of a pump dischargeable in one direction only; means forming with the pump and with said cylinders a high pressure hydraulic press-operating circuit; a reversing valve connected in said circuit for reversing the direction of fluid travel therein to reciprocate the laten, said valve including a valve casing ormed with a valve chamber, and a piston valve movably mounted in said chamber; a valve shifting pressure chamber; a stem extending from said piston valve and into said pressurel chamber; a valve actuating piston secured to said stem and mounted for reciprocatory movements in said pressure chamber; a low pressure pilot circuit; a pilot valve connected in said circuit; hydraulic connections between the pilot valve and said pressure chamber for admitting fluid under pressure from said pilot circuit to said pressure chamber on one side of said valve actuating piston when the pilot valve is shifted in one direction; hydraulicV connections between the pilot valve and said pressure chamber for admitting fluid under pressure from said pilot circuit to said pressure chamber on the opposite side of said piston when the pilot valve is shifted in the other direction; and means for shifting the pilot valve when the platen approaches the end of one of its reciprocatory movements.

8. The combination with a hydraulic press including a reciprocatory platen, a main cylinder, and a platen returning cylinder; of a pump dischargeable in one direction only; means forming with the pump and with said cylinders a high pressure hydraulic pressoperating circuit; a reversing valve connected in said circuit for reversing the direction of Huid travel therein to reciprocate the platen, said valve including a valve casing formed with a valve chamber, and a )iston valve movably mountedv in said cham er; a valve shifting pressure chamber; a stem extending from said piston valve and into said pressure chamber; a valve actuating piston secured to said stem and mounted for reciprocatory movements in said pressure chamber; a low pressure pilot circuit; a ilot valve connected in said circuit; hydrau ic connections between the pilot valve and said pressure chamber for admitting fluid under pressure from said pilot circuit to said pressure chamber on one side of said valve actuating piston when the pilot valve is shifted in one direction; hydraulic connections between the pilot valve and said pressure chamber for admitting fluid under pressure from said pilot circuit to said pressure chamber on the op site side of said piston when the pilot va ve is shifted in the other direction; and means associated with the pilot valve and responsive to the Jressure in the high pressure circuit for shi ting the pilot valve in one direction.

' 9. The combination with a hydraulic press including a reciprocatory platen, a main cylinder, and a platen returning cylinder; of a pump dischargeable in one direction only; means forming with the pump and with said cylinders a high pressure hydraulic press-operating circuit; a reversing valve connected in said circuit for reversing the direction of fluid travel therein to reciprocate theplaten, said valve including a valve casing formed with a valve chamber, and a Jiston valve movably mounted in said chamber; a valve shifting pressure chamber; a stem extending from said piston valve and into said pressure chamber; a valve actuating piston secured to said stem and mounted for reciprocatory movements in said pressure chamber; a low pressure pilot circuit; a pilot valve connected in said circuit; hydraulic connections between the pilot valve and said pressure chamber for admitting fluid under pressure from said pilot circuit to said pressure chamber on one side of said valve actuating piston when the pilot valve is shifted in one direction; hydraulic connections between the pilot valve and said pressure chamber for admitting fluid under pressure from said pilot circuit to said pressure chamber on the opposite side of said pistou when the pilot valve is shifted in the other direction; means associated withl the pilot valve and responsive to the pressure in the high pressure circuit for shifting the pilot valve inf/one direction; and platen actuated means associated with the pilot valve for shifting the latter in the opposite direction.

10. The combination with a hydraulic press including a reciprocatory platen; of a pump dischargeable in one direction only, means forming with the press and with the pump a high pressure hydraulic press-operating circuit; a reversing valve operatively con- Y nected in said circuit; a valve actuating pressure chamber; a piston rod connected to said reversing valve and extending into said pressure chamber; a piston fixed to said rod and Q9 mounted for reciprocatory movements in said pressure chamber for shifting the reversing valve; a low pressure hydraulic pilot circuit; a pilot valve operatively. connected in said low pressure circuit, said pilot valve including a valve casing formed with a valve chamber, a low pressure inlet port communicating with said valve chamber, an .exi haust port communicatingr with said valve chamber, anoutlet port communicating `with said pressure chamber on one side oi the pi s ton and adapted to communicate with said /v/alve chamber, another outlet port com- /municating with said pressure chamber on the opposite side of the piston and adapted to communicate with said valve chamber, a

piston valve mounted for reciprocatory movements in said valvechaniber for alternately placing said outlet ports )in communication with said chamber, means for automatically placing said low pressure inlet port in communication with said exhausty port; and means for shitting said piston valve when the platen approaches the end of one ot its reciprocatory movements.

1l. The combination with a hydraulic press including a reciprocatory platen; of a pump dischargeable in one direction only, means forming with the press and with the pump a high pressure hydraulic press-operating circuit; a reversing valve operatively connected in said circuit; a valve actuating pressure chamber; a piston rod connected to said reversing valve and extending into said pressure chamber; a piston fixed to said rod and pressure chamber for shifting the reversing valve; a low pressure hydraulic pilot circuit; a pilot valve operatively connected in said low pressure circuit, said pilot valve including a valve casing formed with a valve chamber, a low pressure inlet port communicating With said valve chamber, an exhaust port communicating with said valve chamber, an outlet port communicating With said pressure chamber on one side of the piston and mounted for reciprocatory movements in said adapted to communicate with said valve chamber, another outlet port communicating with said pressure chamber on the opposite side ot' the piston and adapted to communicate with said valve chamber, a piston valve mounted for]J reciproeatory moyements in said valve chamber for alternately placing sa id outlet ports in communication with said chamber, a spring relief valve for automatically placing said low pressure inlet port in communication with said exhaust port; and means for shifting said piston valve when the platen approaches the end of one ot its reciprocatory movements.

l2. The combination with a hydraulic press including a reciprocatoryplaten; of a pump dischargeable in one direction only, means forming with the press and with the pump a high pressure hydraulic press-operating circuit a reversing valve operatively connected in said circuit; a valve actuating pressure chambera piston rod connected to said reversing valve and extending into said pressure chambjer; a piston lfixed to said rod and mounted:4 t'or reciprocatory movements in said pressure chamber for shifting the reversing valve; a low pressure hydraulic pilot circuit; a pilot valve operatively connected in said low pressure circuit, said pilot valve ini cluding a valve casing formed with a valve chamber, a low pressure inlet port communi- Aating with said valve chamber, an exhaust port communicating with said valve chamber, an outlet port communicating with said pressure chamber on one side ot the piston and adapted to communicate with said valve chamber, another outlet port communicating with said pressure chamber on the opposite side of the piston and adapted to communi'- atc with said valve chamber, a piston valve mounted for reciprocatory movements in said valve chamber for alternately placing said outlet ports in communication with said chamber, means for automatically placing said low pressure inlet port in communication with said exhaust port; springloaded hydraulic means responsive to the pressure in the high pressure circuit for shifting said piston valve in one. direction when the platen approaches the end of its pressing stroke; and

platen actuated means for shifting said piston valve in the opposite direction when the platen approaches the end of its return stroke.

In testimony whereof, I have hereunto subscribed my name.

WALTER ERNST.

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