US2692583A

US2692583A - Apparatus for controlling the pressure applied to the work in pressing machines

Info

Publication number: US2692583A
Application number: US121032A
Authority: US
Inventors: Edmund N Neckel; Clarence A Ketchum
Original assignee: American Laundry Machinery Co
Current assignee: American Laundry Machinery Co
Priority date: 1949-10-12
Filing date: 1949-10-12
Publication date: 1954-10-26
Anticipated expiration: 1971-10-26

Description

NECKEL ETAL TO THE WORK IN PRESSING MACHINES Filed Oct. 12, 1949 APPARATUS FOR CONTROLLING THE PRESSURE APPLIED .3, 5s 5e 57 62a.

IN N

Oct. 26, 1954 INVENTORS EDMUND N. NECKEL 2.

CLARENCE A. KETCHUM Patented Oct. 26, 1954 UNITED STATS TENT OFFICE APPARATUS FOR CONTROLLING THE PRES- SURE APPLIED TO THE WORK IN PRESS- ING MACHINES Edmund N. Neckel and Clarence A. Ketchum,

Hamilton County, Ohio, assignors to The American Laundry Machinery Company,

Cincinnati,

15 Claims. 1

This invention relates to control apparatus for fluid pressure operated pressing machines, and more particularly to control apparatus capable of operation to cause application to the work, selectively, of either full or reduced pressure, thereby adapting the machine for high quality work on different kinds of garments, fabrics or the like.

Both laundry presses and outer garment presses of the class to which this invention relates are used to press a wide variety of garments and fabrics, from linens and other goods which require rather heavy pressure to silk and rayon goods which react more favorably to considerably lighter pressure. The ordinary press, while usually capable of screw or equivalent adjustment of the operating link or lever mechanism, or of the pressure of the fluid pressure supply, to vary the pressure applied to the work, is not intended to be so operated as to produce heavy pressure on one stroke and light pressure on the next. It is set or adjusted for one desired working pressure, either high or low, and is so operated on one class of work for hours at a time. Even then, any reduction in the power of the fluid pressure supply affects not only the pressure applied to the work, but also that used to close the press, thus reducing the closing speed and consequently the output.

One object of the present invention is to provide improved press control mechanism, capable of application to any fluid pressure operated press, in which at the will of the operator, at any time or during any individual stroke or press operation, the pressure applied to the work may be reduced, but without reducing the pressure employed to close the press, thus maintaining the same high rate of output secured When full or high pressure is being applied.

Another object is to provide improved press control mechanism so constructed and arranged that when the press is operated it is first closed quickly to a safe position under full pressure supply, following which the operating pressure supplied to the working cylinder or motor is reduced, thus producing the final squeeze or pressure effect upon the work at a reduced or lower pressure suitable for the more delicate fabrics, such as silk, rayon or the like.

Still another object is to provide improved press control mechanism including a simple, easily and quickly actuated operator operated control device capable of adjustment to either of two or more positions, in one of which the press is closed safely and final pressure is then applied by the full power of the pressure supply, and in the others of which the press is closed safely by full power but the final pressure applied to the work is at a lower or reduced value.

Another object is to provide improved press control mechanism of the character before described, in which, when flnal pressure applied to the work is at a reduced value, the drop in pressure is sensitive or responsive to, or is produced, in step with motion of relative approach between the pressing members, occurring when they have been brought into close juxtaposition, that is, closed safely, so that the press is closed quickly, but high pressure is not applied to the work.

A further object is to provide improved press control mechanism including a master control valve, operator controlled or actuated, through which fluid pressure flows from the source to the operating motor by way of a two-way valve and two branch conduits, one of which includes a pressure reducing valve, said two-way valve being adjustable to direct the flow, selectively, through either branch to thus selectively supply either high or low pressure to the motor.

Another object is to provide improved press control mechanism, including such a two-way valve, in which operation of the valve is controlled or produced by the operator, by closing movement of the press, or by both.

Further objects of the invention in part are obvious and in part will appear more in detail hereinafter.

In the drawings, which represent one suitable embodiment of the invention,

Fig. 1 is a compound view in diagram form, illustrating a press, air flow channels, and in section at A, B, C and D, four units of the press control system, units B and 0 being in section on the lines B-B and C-C, Fig. 2;

Fig. 2 is a partial front elevation of unit C; and

Fig. 3 is a detail cross section on the line 3-3, Fig. 1.

The press itself may be of any suitable form or arrangement, embodying either one or two fluid pressure operating motors. For convenience, and in no sense of limitation,-a single motor press is conventionally shown. This includes pressing head it and bed II, the latter mounted upon frame [2 and the former upon main lever l3 connected to the upper one of two toggle links l4, l5, the knuckle I6 of which is pivotally connected to the piston rod l1 actuated by piston H8 in the cylinder it of a single acting fluid pressure motor attached to the frame. The conduit by which fluid pressure is supplied to the motor is indicated at 29, While 21 indicates another conduit connected to a port in the side of the cylinder by which fluid pressure may be conducted to control parts, as will later appear. This port is located at such a point that the piston passes beyond it when the press has been safely closed, i. e., the head has approached so closely to the bed that the operator cannot insert his hand between them. While the head may contact the work, no real pressure is yet applied. 22 indicates the usual press opening spring.

Of the four press control units shown in Fig. 1, unit A includes the left hand manual control valve, B the right hand manual control valve, C the master control valve and release valve, and D the pressure reducing valve, the two way valve, and the manually operated pressure control valve.

One well known form of control mechanism for presses of the kind here involved includes a master control valve, operator operated or controlled, through which fluid pressure is supplied to the press motor for both closing the press and applying final pressure. Such an arrangement for example, is shown in an application for Press Control Mechanism, Serial No. 54,988, filed October 16, 1948, by Edmund N. Neckel, now Patent No. 2,567,444, to which reference may be had if desirable or necessary.

According to the present invention the conduit or channel from the master control valve to the press motor includes two branches, both leading to the motor, one of which is unrestricted and the other of which includes a pressure reducing valve. A two way valve may be adjusted to cause flow, selectively through either branch. Its position therefore determines whether the pressure supplied to the motor is high or low. In the form here shown this valve normally lies in high pressure position, to which it is biased. Thus the press is closed quickly by supplying full or high pressure to its motor. When the press is safely closed, as before referred to, the valve may be suddenly shifted to its low pressure position, thus causing final pressure upon the work at low pressure rather than high. Whether the valve is so shifted depends upon the will of the operator, who is provided with control means by operation of which he is able to cause the shift or not, as he chooses. If not, final pressure upon the work is at full or high pressure, as though the two-way valve and pressure reducing valve did not exist.

Examining Fig. 1, unit 3 includes an inlet chamber 23 communicating with fluid pressure supply pipe 24 and in which is removably mounted the filter screen 25, through which air flows to the supply channel 26, thence through pipe 21 to a normally closed right-hand combination inlet and exhaust valve, marked generally 28, actuatable by manual 29. Pressure also flows from channel 26, through a, cross passage 26a (dotted lines, Fig. 2) and past adjustable needle valve 26b, to the supply chamber 260 of the master control valve unit 0, which is part of the same casting as unit B. Beyond valve 28, pressure flows by pipe 59 to unit A.

Unit A includes the left-hand combination inlet and exhaust valve 3! actuated by manual 32 and, as usual, is widely separated from unit B to compel the use of both hands in closing the press. From valve 3! pressure flows to unit C.

Unit C includes both a normally closed release valve 33, like valves 28 and SI, operated by manual 33a, and the master control valve, the valve member of which is marked 34. This master control valve and its operating and control mechanism may be of any suitable form, such as that shown and described in the aforesaid Neckel application, although it is here shown as of different form. Its details will be described later. It is suffiicient here to say that when

valves

28 and 3| are opened, pressure flows from valve 3| by pipe 35 to the chamber of a double acting servomotor piston 36, which moves over (to the left in Fig. 1) and opens the master valve member 34 to its supply chamber 260. Thereupon pressure flows to and through pipe 31, leading to pipe 29 and motor 19 before referred to. Pipe 3'! communicates directly with unit D.

Unit D includes in one assembly the two-way valve before referred to, the pressure reducing valve, and the manually operatable pressure control valve.

The two-Way valve, of double poppet form, marked 38, is actuated by single acting piston 39 working in chamber 40, and is biased toward its high pressure position (shown in Fig. 1) by spring 4|. It works in chamber 42 to which pipe 3! is connected, and controls flow to pipe 20 either through channel 45, as shown, or, when in its other, low pressure position, by way of pipe 44 and a pressure reducing valve 45 provided with reduced pressure adjusting screw 45a. This is of any standard or suitable form, its details forming no part of the present invention. Gauge 46 indicates the reduced pressure value.

Fluid pressure for actuating piston 39 comes at first from an extension 21a of pipe 2| to and through the manual control device and by connector 4'! to chamber 40.

The manual control device, indicated at 48 is of double piston form sliding in chamber 49 and actuated by knob 59. When in the position shown it cuts off flow from pipe 21a to chamber 40. When depressed, its annular channel 5! establishes communication from pipe 21a to connector 41.

Full line pressure to maintain piston 39 and. valve 38 in their low pressure positions flows from valve chamber 42 through a space around the piston stem and thence through channel 52 to chamber 40. To prevent back flow of such pressure through pipes Zia and 2| to the motor cylinder pipe 21 is provided with check valve 53.

In the particular form of master control valve mechanism shown, the master control valve 34 is biased to closed position by spring 54. The opposite end of its stem 55 abuts a poppet form exhaust valve 56 which, when closed, cuts off exhaust from chamber 5'! through annular exhaust channel 58 to the exhaust outlet 59 (Fig. 3). One wall of chamber 5'! is the bottom of a cup-shaped member 69 secured to the main casting by bolts 61 and in the chamber 62 of which slides the double acting piston 36 before mentioned and to which the outlet valve 56 is connected. Full line pressure supplied by way of pipe 35 enters piston chamber 62 and becomes effective to move piston 36 and valve 56 to the left, thus closing the outlet through channel 58, and at the same time opening valve 34, thus opening a passage for the flow of pressure from channel 260 to pipe 31, as before described.

The operation is as follows:

Let us assume that all parts are in the position shown in Fig. 1. The press is open, full line fluid pressure is available in the source to which the supply pipe 24 is connected, and the various valve devices are in the position shown, all thereof being closed except valve 56, which is open, and

valves

38 and 48 which are in the full or high pressure position. The operator desires to operate the press, using high or full line pressure both to close the press and to apply pressure to the work. Hence, he leaves the selective control valve 48 in the position shown.

Depression of

manuals

29, 32 causes the flow of pressure from the source through

valves

28, 3| to chamber 52, and also through channel 26 to supply chamber 260 of the master control valve. Servo motor piston 36 moves over, thus closing outlet valve 56 and opening master control valve 3 5. Immediately, pressure flows past the valve 341 and by way of pipe 31 and channel 43 to pipe 23 and thence into the chamber of the motor l9, moving over its piston and advancing the head toward closed relation with the bed. The operator is compelled to hold her hands on the

manuals

23, 32 until the press head has reached safely closed position or relation with respect to the bed, i. e., to a position in which the piston l8 has passed the port opening to pipe 2 I. Thereupon, pressure flows from the motor cylinder chamber through pipe 2! and past check valve 53 and through pipe 64 into chamber '5. There it becomes effective upon the closed exhaust valve 53, to maintain the same closed and at the same time to hold the master control valve 34 open.

Although pressure is being supplied to pipe extension Zla, it is not eiTective upon servo motor piston 39 of the pressure control valve, due to the position of valve 48.

Accordingly, full line pressure continues to flow through pipe 31, channel 43 and pipe 20 to the motor cylinder, applying final pressure, at high or full line pressure value, to the work between the pressing members. The port in the side of the cylinder being passed the operator can remove his hands from the

manuals

29, 32. Although this evacuates pressure from chamber 32, the master control valve 33 is maintained in its open position by the pressure effective in chamber 51.

When the pressing operation has continued for a sufficient length of time, the operator opens the press by depressing manual 33a. The elTect is to close the outlet through the exhaust valve and to establish communication from pipe 63 past valve 33 to pipe 65 (at the top and bottom in unit C, Fig. 1) which communicates through a small port or opening in member 60 with the front portion 62a of the servo motor chamber 52. There it becomes efiective upon piston 33 with sufficient force to preponderate over other pressures and move said piston to the right and to open exhaust valve 56. Thereupon, pressure in line 2| and in the motor cylinder 19 is evacuated through exhaust channel 58, and the press head starts to rise. At the same time, communication has been opened between pipe 31 and the exhaust passage 58, so that evacuation of the motor cylinder continues through pipe 20 leading to that path, until the press is in full open position. Release of manual 33a, of course, closes exhaust Valve 33. All parts have been returned to their original positions ready for another operation.

Should the operator desire to perform a pressing operation where the press is closed by full power pressure, but final pressure upon the work is produced by low or reduced pressure value, he first depresses the button 50, moving valve 53 downwardly to a position in which its annular channel 5| establishes communication betweenpipe 2 la and connector 41. Press operation then occurs as follows:

The two

manuals

29, 32 are depressed as before, with corresponding operations up to the point where the piston l8 passes beyond the port leading to pipe 2|. Full line pressure therefore flows through said pipe not only to chamber 5'1, to maintain the exhaust valve closed and the master control valve open, but also to chamber of the pressure control valve mechanism. The efiect is to move piston 39 to the right in Fig. 1, shifting valve 38 to its right-hand position, in which it closes the opening to channel &3. Thereupon, fluid pressure flows, at full line pressure, through pipe 44 to and through pressure reducing valve 45 and thence again through pipe A4 back to channel 43 and through pipe 20 to the motor cylinder, but at a pressure reduced below that of full line pressure in accordance with the particular setting at the time of the pressure reducing valve 45.

As a result, the final pressure applied to the work, during the final squeeze operation is at the reduced instead of at the high pressure.

When valve 3 closes to terminate direct flow of high pressure fluid through chamber 43 and conduit 20 to cylinder IS, the high pressure in cylinder I9 immediately begins to drop because the piston l8 continues to advance a substantial amount further in cylinder l9, and the pressure fluid flow proceeds through the reducing shunt conduit 44 just after the motor piston it passes the outlet to conduit 2!.

In a commercial embodiment at present in use, when the change takes place from high to low pressure, there is about three-quarters of an inch between the adjacent working surfaces of the press head and the buck. This means that there is a substantial movement of piston l8 still to take place before said working surfaces contact, and a further increment of movement taken up in compressing the padding. Each increment of movement past the pressure-change point reduces correspondingly the pressure, and the low pressure has taken over by the time contact of the working surfaces has been effected.

The positioning of the outlet to conduit 2| on the wall of cylinder I 9, and the dimensions and arrangement of rod I"! and the toggle arms it and !5 are of course so arranged and predetermined that the above described change of pressure takes place at the time and with the result described.

As soon as valve 38 moves to the right, fluid pressure from pipe 3'! flows to chamber 40 by way of channel 52, so that the pressure control valve 38 is maintained in its second or low pressure position by full line pressure. However, the full line pressure effective in chamber 40, although it is effective through pipe 2 la in chamber 52, to maintain the exhaust valve 56 closed, cannot back up through pipe 2i and become ef fective in the chamber of motor l9, due to the stopping effect of check valve 53, as will be readily apparent. Release operation, when the press has been closed in the manner described, is the same as before. The release valve manual 33a is depressed, thereby causing the flow of full line pressure to chamber Bid with actuation of motor piston 36 to the right, followed by the opening of exhaust valve 56 and the closing of master control valve 34. Pressure is thereupon evacuated entirely, not only from the motor cylinder i9, but also from the various valve and piston chambers, except the chamber 62a. Pressure there is exhausted or evacuated, just as before,

when the release manual 33a is released and valve 33 moves to its exhaust position.

In this control mechanism, therefore, it is possible to operate a press rapidly, time after time with the final pressure upon the work either at high or full line pressure, or at low or reduced pressure, as preselected by the operator in his adjustment of control valve 48. At any time, even for a single press operation, this valve may be adjusted to its other position, to predetermine the correct final pressure. During all operations, the press is closed by the application to the press operating motor of full line pressure, so that there is no sacrifice of speed at any time, even though the final pressure may be at low rather than at high pressure.

been safely closed to a position in which the operator cannot introduce her hands between the pressing members.

The effects described are secured by dividing the channel between the master control valve and press motor into two branches, one containing or including a pressure reducing valve, flow through either of the branches being determined by the position of a shiftable control valve, shifting of which is automatically produced when the press has been closed to safe position, but operation of which depends upon the position to which the operator has adjusted the selective control valve 48.

The mechanism is relatively simple and is quite efiicient in operation.

Other advantages of the invention will be apparent to those skilled in the art.

What we claim is:

1. Apparatus for controlling the supply of fluid pressure to the operating motor of a pressing machine, comprising in combination with said motor, a source of pressure fluid, master valve means biased to shut-01f position communicating with the source and connected to the motor and adjustable to open position, manually controlled means for so adjusting said valve means, a by-pass channel from said valve means to the motor around said connection and including pressure reducing valve means, and pressure controlling valve means between the master valve means and the motor adjustable to either of two positions, in one of which full line pressure is supplied to the motor through said connection and in the other of which reduced pressure is supplied to the motor through said channel and said pressure reducing valve means.

2. Apparatus for controlling the supply of fluid pressure to the operating motor of a pressing machine, comprising in combination with said motor, a source of pressure fluid, master valve means biased to shut-oil position communicating with the source and connected to the motor and adjustable to open position, manually controlled means for so adjusting said valve means, a by-pass channel from said valve means to the motor around said connection and including pressure reducing valve means, pressure controlling valve means between the master valve means and the motor adjustable to either of two positions, in one of which full line pressure is supplied to the motor through said connection and in the other of which reduced pressure is supplied to the motor through said channel and said pressure reducing valve means, and means operatable at will by the operator for controlling adjustment of said pressure controlling valve means.

3. Apparatus for controlling the supply of fluid Further, in all cases, final pressure is not secured until the press has pressure to the operating motor of a pressing machine, comprising in combination with said motor, a source of pressure fluid, master valve means biased to shut-01f position communicating with the source and connected to the motor and adjustable to open position, manually controlled means for so adjusting said valve means, a by-pass channel from said valve means to the motor around said connection and including pressure reducing valve means, pressure controlling valve means between the master valve means and the motor adjustable to either of two positions, in one of which full line pressure is supplied to the motor through said connection and in the other of which reduced pressure is supplied to the motor through said channel and said pressure reducing valve means, and said pressure controlling valve means being adjustable to reduced pressure position only after the press is safely closed, and means by which said pressure controlling valve means can be adjusted to reduced pressure position.

4. Apparatus for controlling the supply of fluid pressure to the operating motor of a pressing machine, comprising in combination with said motor, a source of pressure fluid, master valve means biased to shut-off position communicating with the source and connected to the motor and adjustable to open position, manually controlled means for so adjusting said valve means, a by-pass channel from said valve means to the motor around said connection and including pressure reducing valve means, pressure controlling valve means between the master valve means and the motor adjustable to either of two positions, in one of which full line pressure is supplied to the motor through said connection and in the other of which reduced pressure is supplied to the motor through said channel and said pressure reducing valve means, said pressure controlling valve means being adjustable to reduced pressure position only after the press is safely closed, and means controlled at least in part by motor operation for adjusting said pressure controlling valve means to reduced pressure position.

5. Apparatus for controlling the supply of fluid pressure to the operating motor of a pressing machine, comprising in combination with said motor, a source of pressure fluid, master valve means biased to shut-off position communicating with the source and connected to the motor and adjustable to open position, manually controlled means for so adjusting said valve means, a bypass channel from said valve means to the motor around said connection and including pressure reducing valve means, pressure controlling valve means between the master valve means and the motor adjustable to either of two positions, in one of which full line pressure is supplied to the motor through said connection and in the other of which reduced pressure is supplied to the motor through said channel and said pressure reducing valve means, and means controlled by said pressure controlling valve means for applying full source pressure to the master valve means for maintaining the latter in open position.

6. Apparatus for controlling the supply of pressure fluid to the operating motor of a pressing machine, comprising in combination with said motor, a source of fluid pressure, master valve means biased to shut-01f position communicating with the source and connected to the motor and adjustable to open position, manually controlled mean for so adjusting said valve means, a by-pass channel from said valve means to the motor around said connection and including pressure reducing valve means, pressure controlling valve means between the master valve means and the motor adjustable to either of two positions, in one of which full line pressure is supplied to the motor through said connection and in the other of which reduced pressure is supplied to the motor through said channel and said pressure reducing valve means, means for preventing adjustment of said pressure controlling valve means to reduced pressure position until the press is safely closed, and means controlled by said pressure controlling valve means for applying full source pressure to the master valve means for maintaining the latter in open position.

7. Apparatus for controlling the supply of fluid pressure to the operating motor of a pressing machine, comprising in combination with said motor, a source of pressure fluid, master valve means biased to shut-off position communicating with the source and adjustable to open position, conducting means extending from said valve means to the motor and provided with two branches, one of which includes pressure reducing means, said conducting means including valve means for selectively causing flow of pressure fluid to the motor through either of said branches and thus at either full or reduced pressure, a fluid pressure operated servomotor connected to said last named valve means for operating the same, and means controlled by the motor for supplying pressure fluid to said servomotor.

8. Apparatus for controlling the supply of fluid pressure to the operating motor of a pressing machine, comprising in combination with said motor, a source of pressure fluid, master valve means biased to shut-off position communicating with the source and adjustable to open position, conducting means extending from said valve means to the motor and provided with two branches, one of which includes pressure reducing means, said conducting means including valve means for selectively causing flow of pressure fluid to the motor through either of said branches and thus at either full or reduced pressure, a fluid pressure operated servomotor connected to said last named valve means for operating the same, and a pressure fluid supply conduit for said servomotor communicating with said operating motor cylinder at a point near full stroke of the piston thereof.

9. Apparatus for controlling the supply of fluid pressure to the operating motor of a pressing machine, comprising in combination with said motor, a source of pressure fluid, master valve means biased to shut-off position communicating with the source and adjustable to open position, conducting means extending from said valve means to the motor and provided with two branches, one of which includes pressure reducing means, said conducting means including valve means for selectively causing flow of pressure fluid to the motor through either of said branches and thus at either full or reduced pressure, a fluid pressure operated servomotor connected to said last named valve means for operating the same, a pressure fluid supply conduit for said servomotor communicating with said operating motor cylinder at a point near full stroke of the piston thereof, and supplemen- 10 tary means for supplying full source pressure to said servomotor, said supply conduit including a check valve seating toward the operating motor.

10. Apparatus for controlling the supply of fluid pressure to the operating motor of a pressing machine, comprising in combination with said motor, a source of pressure fluid, master valve means biased to shut-oil? position communicating with the source and adjustable to open position, conducting means extending from said valve means to the motor and provided with two branches, one of which includes pressure reducing means, said conducting means including valve means for selectively causing flow of pressure fluid to the motor through either of said branches and thus at either full or reduced pressure, a fluid pressure operated servomotor connected to said last named valve means for operating the same, a pressure fluid supply conduit for said servomotor communicating with said operating motor cylinder at a point near full stroke of the piston thereof, and a manually operatable cut-ofl valve in said supply conduit.

11. Apparatus for controlling the supply of fluid pressure to the operating motor of a pressing machine, comprising in combination with said motor, a source of pressure fluid, master valve means biased to shut-off position communicating with the source and adjustable to open position, conducting means extending from said valve means to the motor and provided with two branches, one of which includes pressure reducing means, said conducting means including valve means for selectively causing flow of pressure fluid to the motor through either of said branches and thus at either full or reduced pressure, a fluid pressure operated servomotor connected to said last named valve means for operating the same, a pressure fluid supply conduit for said servomotor communicating with said operating motor cylinder at a point near full stroke of the piston thereof, a manually operatable cut-ofl valve in said supply conduit, and means for supplying full source pressure to said servomotor independently of said supply conduit.

12. In a pressing machine embodying cooperating relatively movable pressing members and a fluid pressure operated motor for closing the press by bringing the pressing members into juxtaposition and for thereafter applying pressure to the work between said pressing members, the combination with said motor of a source of pressure fluid, conduit means for connecting said source to the motor and including valve means biased to shut-off position, means under the control of the press operator for opening said valve means, said conduit means between said valve means and said motor having one conduit portion effective for the supply of pressure fluid at full line pressure to the motor and having another conduit portion in parallel with said first mentioned conduit portion and containing a pressure reducing means and effective for the supply of pressure fluid at a reduced pressure to the motor, valve means for closing said flrst mentioned conduit portion to thereby enable only pressure fluid at a reduced pressure to be supplied to the motor, and means under the control of the press operator and effective to close said conduit portion valve means only after the press has been closed by bringing its pressing members into juxtaposition, whereby after the press has been closed by pressure fluid at full line pressure, either pressure fluid at full line pressure or pressure fluid at a reduced pressure can be su plied to the motor for the application of pressure to the work between the pressing members.

13. In a pressing machine embodying cooperating relatively movable pressing members and a fluid pressure operated motor for closing the press by bringing the pressing members into safe juxtaposition and for thereafter applying pressure to the work between said pressing members, the combination with said motor of a source of pressure fluid, conduit means for connecting said source to the motor and including valve means biased to shut-off position, means under the control of the press operator for opening said valve means, said conduit means between said valve means and said motor having one conduit portion eifective for the supply of pressure fluid at full line pressure to the motor and having another conduit portion in parallel with said first mentioned conduit portion and containing a pressure reducing means and effective for the supply of pressure fluid at a reduced pressure to the motor, valve means for closing said first mentioned conduit portion to thereby enable only pressure fluid at a reduced pressure to be supplied to the motor, an means capable of being rendered effective by the press operator to automatically close said conduit portion valve means when the press has been closed by bringing its pressing members into juxtaposition, whereby after the press has been closed by pressure fluid at full line pressure, pressure fluid at a reduced pressure is supplied to the motor for the application of pressure to the work between the pressing members.

14. In a pressing machine embodying cooperating relatively movable pressing members and a fluid pressure operated motor for closing the press by bringing the pressing members into safe juxtaposition and for thereafter applying pressure to the work between said pressing members, the combination with said motor of a source of pressure fluid, conduit means for connecting said source to the motor and including valve means biased to shut-off position, means under the control of the press operator for opening said valve means, said conduit means between said valve means and said motor having one conduit porbe supplied to such valve means from the motor after the press has been closed, and a manually controlled valve means in said last mentioned conduit means, the open or the closed position of said last mentioned valve means determining whether the pressure of the fluid supplied to the motor for the application of pressure to the work is to be at a reduced pressure or at full line pressure.

15. In a pressing machine embodying cooperating relatively movable pressing members and a fluid pressure operated motor for closing the press by bringing said pressing members into juxtaposition and for thereafter applying pressure to the work between said pressing members, the combination with said motor of a source of pressure fluid, a main conduit in communication with said source and with said motor, a by-pass conduit also in communication with said source and with said motor, pressure reducing means in said bypass conduit, a valve biased to a first position in which it permits pressure fluid flow in said main conduit, but movable to a second position in which it terminates pressure fluid flow through said main conduit and permits pressure fluid flow through said by pass conduit and said reducing valve, movable means operatively connected to said motor and to one of said pressing members for moving the last said pressing member substantially into initial pressing contact with the other said pressing member upon admission of pressure fluid at full pressure to said motor, and pressure-change initiating means operatively connected to said motor and said valve, and sensitive to and responsive to movement of said movable means, for moving said valve from high pressure flow position to reduced pressure flow position when said initial contact is approached to thereby effect movement of said pressing members into final pressing engagement at reduced pressure.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,249,736 Frink Dec. 11, 1917 1,999,400 Davis Apr. 30, 1935 2,115,414 Davis Apr. 26, 1938 2,232,038 Stone Feb, 18, 1941 2,341,696 Davis Feb. 15, 1944 2,375,946 Reichelt May 15, 1945 2,400,233 Hicks May 14, 1946 2,492,477 Henly et a1 Dec. 27, 1949 2,566,811 Stevenson Sept. 4, 1951 FOREIGN PATENTS Number Country Date 408,900 Great Britain Apr. 19, 1938 487,530 Great Britain June 22, 1938