US2445248A - Cutting machine - Google Patents

Description

July 13, 1948. w. R. SPILLER 2,445,243

CUTTING MACHINE Filed July 22, 1946 3 Sheets-Sheet 1 July 13, 1948. w. R. SPILLER CUTTING MACHINE 3 Sheets-Sheet 2 Filed July 22, 1946 July 13, 1948. w. R. SPILLER CUTTING MACHINE 3 Sheets-Sheet 3 Filed July '22, 1946 Patented July 13, 1948 I 2,445,248 cur'rmc momma William R. Spiller, Dayton, 'Ohio, assignor to Harria-Seybold Company, Cleveland, Ohio, a

corporation of Delaware Application July 22, 1946, Serial No. 685,429

15 Claims.

This invention relates to the operation and control of the clamping mechanism of paper cutting machines.

Machines used for cutting and trimming piles of paper of substantial thickness commonly employ a cutting knife mounted for vertical movement to and from cutting position and a clamp mechanism for holding the pile firmly in proper position with respect to the knife. This clamp member may be coupled with the drive mechanism for the knife for properly coordinated action and high clamping pressure during the cutting cycle, and it is commonly provided with counterbalance means such as a spring counterbalance for automatically returning it to its inoperative position after the cutting stroke. In the operation of such machines, it is desirable for the movable clamp member to be brought into engagement with the paper'in advance of the cutting cycle of the knife and independently thereof, inorder to gauge the location of the out line, particularly with reference to printed stock, and insure proper positioning for cutting. This preliminary application of the clamp is commonly carried out with relatively moderate pressure, usually no more than sufllcient to express air from between the sheets in the pile and thus to aid in securing the proper position of the material for cutting. Thereafter the full clamping pressure is applied in conjunction with the cutting cycle of the knife.

In operation, the preliminary application of the clamping mechanism is commonly initiated by means of a treadle or like externally operable member independent of the main operating mechanism for the cutting cycle of the machine. If the connection to the clamp mechanism is such that the latter is operated by direct physical effort on the treadle, a substantial force is required of the operator for satisfactory operation. Not only must the force of the counterbalance be overcome to bring the clamp into clamping position, but the necessary preliminary clamping pressure must be developed. In some cases. it is necessary during this preliminary clamping action to exert suflicient force to compress folded sheets adequately for accurate trimming. In addition,

'the clamp should be held in its preliminary clamping position until the cutting cycle of the machine begins, since if the clamp member is allowed to go up and thereafter descend in conjunction with the knife, there is a strong tendency for the pile' to shift upon the second application of the clamp and to lose the desired alignment. It will accordingly be seen that when the machine is so constructed that the clamp must be mechanically operated by physical effort on the treadle, the work is definitely fatiguing for the operator.

It is accordingly one of the principal objects of tive hydraulic system for operating the gauging mechanism of a paper cutting machine and which may be readily controlled by means of a simple treadle or like operating member.

An additional object is to provide a hydraulic operating system for the above purpose wherein substantially the only force on the treadleto be overcome by the operator is the pressure of a spring which need be of no greater tension than sufllcient to return the treadle to inoperative position when released.

It is also an object of the invention to provide for the full control of the preliminary movements of the clamping mechanism of a paper cutting machine in either direction, as well as over the pressure range capable of being exerted thereby, by simple manipulation of a treadle or like operating member with minimum physical effort on the part of the operator.

A further object is to provide a servo mechanism for the preliminary operation of a clamping member as described above which includes a fluid pressure motor responsive to the introduction of hydraulic fluid to cause movement of the clamping mechanism and wherein movement of the clamp member in either direction may be controlled by adjustment of a valve member regulating the relative flow of hydraulic fluid to the fluid motor and by-passing the fluid motor.

A still further object is to provide a servo operating mechanism for the above purpose which is self-contained and adapted for mounting as a unit on a paper cutting machine.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings, in which like characters of reference designate like parts throughout- Fig. 1 is a perspective view illustrating a paper cutting machine provided with a hydraulic operating system for its clamping mechanism in accordance with the present invention;

Fig. 2 is an enlarged front view of the hydraulic operating system for the clamping mechanism of the paper cutting machine shown in Fig. l, with part of the front of the casing broken away and the internal mechanism shown in section substantially on the line 2-2 of Fig. 6;

. Fig. 3 is a side view, partly broken away, of the mechanism shown in Fig. 2;

Fig. 4 is a fragmentary view in vertical section on the line H of Fig. 2 and also of Fig. 6, showing details of the passages for the hydraulic fluid and the valve controlling these passages;

' lower end of this piston extends oiit'from the Fig. 5 is a fragmentary front view illustrating I the mounting for the treadle operating mechanism shown in Fig. 2, the view being partially in section on the line 5-5 of Fig. 3;

Fig. 6 is a top view of the mechanism shown in Fig. 2, with the top of the casing and parts car-- ried thereby removed to show internal construction;

Fig. 7 is an enlarged and diagrammatic phantom view in perspective of a part of the cylinder block and casing shown in Fig. 2, to show the fluid passages and other bores therein;

Fig. 8 is a fragmentary section similar to Fig. 4, but showing the valve moved to a position wherein it causes actuation of the clamp member; and

Fig. 9 is a somewhat diagrammatic fragmentary section illustrating the movement of the piston and clamp operating lever in response to movements of the valve as indicated in Fig. 8.

In the drawings, which illustrate a preferred embodiment of the invention, the cutting machine shown in Fig. 1 includes a work table l adapted to receive the pile to be cut, as indicated at H, a. cutting knife I2 mounted for shearing movement with respect to the work table l0, and a clamp member l3 mounted closely adjacent the knife l2 for similar -vertical movement. In the operation of this cutting machine, the clamp is may be brought into initial clamping position in advance of the knife by actuating the threadle l at the front of the machine, this position of the clamp being indicated in dotted lines in contact with the pile. This initial operation of the clamp need be only with sufflcient pressure to hold the paper firmly and to express air trapped between the individual sheets in the pile, thus enabling the operator to locate the out lineon printed stock before the cutting cycle of the machine is begun. Thereafter the cutting cycle is initiated by a suitable actuating member, such as the lever l5, and full clamping pressure is exerted, and at the same time the knife is put through its cutting stroke by means of the links H, the power for this operation being supplied from motor I8 to the main drive shaft 20 through pulleys 2i and 22 and belts 23. Suitable counterbalance mechanism such as spring counterbalances for the clamp are provided Within the cutting machine and serve to return it to the inoperative upper position as soon as positive pressure is released for the return stroke. Members 25 in Fig. 2 represent bearings for the crank shaft 26 positioned within the cutting machine shown in Fig. 1.

The mechanism of the invention for accomplishing the initial operation of clamp l3 as described includes a casing 30 bolted or otherwise secured to the front of the cutting machine and having on its under side a downwardly projecting yoke 32 in which a lever 33 is pivotally mounted by means of shaft 34 as shown in Figs. 2 and 3. The opposite end of this lever is connected to an upwardly extending arm 55 by means such as the double yoke 36. The upper end of arm 35 is in operative connection with clamp member 13 such that vertical movement of the arm will cause similar movement of the clamping member.

To provide for such movement. a piston 40 is mounted for reciprocal movement in a cylinder 4| formed in a block 42 integrally formed or otherwise secured within the interior of casing 30. The

casing through a packing chamber containing packing 43 held under compression between a spring 44 and the outer angular cap 45. The lower end of piston 40 and lever 33 are positioned for relative engagement such that downward movement of the piston will result in a downwardly swinging movement of the lever about its pivot 34. In order to provide for minimizing friction between piston 40 and lever 33, a roller 48 is pivotally secured to the lever for engagement with the bottom face of the piston as shown particularly in Figs. 2 and 9. In accordance with the invention, movement of treadle I5 is transmitted through a. hydraulic operating system to cylinder 4| and results in downward movement of piston 40, as viewed in Fig. 2, and a corresponding downward movement of lever 33 and arm to bring the clamp member l3 similarly downward into its initial clamping position as described.

Casing 30 is largely hollow, as shown in Fig. 2, to provide a sump containing a quantity of hydraulic fluid 50. A pump 5| has itsintake 52 extending into the hydraulic fluid and is shown in Fig. 2 as mounted within the interior of casing 30 and operated through pulleys 53 and 54 and belt 55 by motor 55 mounted at the top of casing 30. To provide for ready adjustment of the ten sion of belt 55, motor 56 is pivotally mounted at one side, as shown in Fig. 3, by means of legs 51 on a. shaft 58 carried by an upwardly projecting tongue member 59 on the top of casing II, and a jack screw 60 at the opposite side of motor 56 provides for pivotal movement of the motor about shaft 58 to increase or decrease the tension on belt 55. A housing Bl covers this belt drive and is mounted by means of a tie bar 62 on motor legs 51, this housing being partly broken out in Figs. 2 and 3 to show theinterior construction. A illiing opening closed by a breather 63 at the top of casing 30 provides for maintaining the fluid level within the casing, and a measuring stick 54 is also indicated for measuring the level of fluid 50, which may fill the casing approximately three-quarters full.

The outlet line 65 of pump 5! leads to a series of passages within the cylinder block 42, including a connection to cylinder 41 and a by-pass of this connection. As shown in Figs. 4 and 8, the bore 66, shown as vertically arranged within the cylinder block, is connected at its upper end with the discharge line 65 from the pump and at its lower end leads into a transverse bore 61, which in turn leads to an additional bore 68 opening back into the sump. As shown in Figs. 2 and 9, passage 10 above bore 61 connects bore 56 with an opening 1| in the side of cylinder 4 I.

With this construction, when the connection between bores 66 and 61 is open, the fluid pumped by pump 5] by-passes cylinder 4i and circulates continually through discharge line 65 and bores 66 and 51 to bore 68 and then back into the sump. If this connection between bores 86 and 61 is closed, the output of the pump will be forced into cylinder 4| to increase the pressure therewithin and thus bring about motion of piston 40 and clamp l3 as described.

The invention accordingly provides valve means for controlling the flow of fluid between bores 88 and 61 in response to movement of treadle l5 to control the clamping mechanism. A valve stem 15 is mounted for sliding movement in bore 81 and is formed with one portion 18 of a diameter substantially equal to that of the bore, and an additional portion 17 of reduced diameter. Thus when the portion 11 is in register with the bore I, there will be provided an adequate opening tor the hydraulic fluid around the valve portion 11 to permit continuous circulation of the fluid by way of passages 68, 61 and 88 and thus prevent movement of the piston, these relative positions of the parts being indicated in Fig. 4. On the other hand, when the valve portion 18 is in register with bore 6i. it will substantially block the latter bore as shown in Fig. 8 and thus force the output of the pump through the bore 10 into the cylinder 4| as described. Also, in order to provide for controlled passage of fluid from bore 68 into bore 01 at intermediate rates. valve portion 18 is notched at It, as shown in Figs. 4 and 8. to provide a portion of progressively varying crosssectional area intermediate the large valve portion It and the smaller portion 11. The portion 18 at the end of valve stem I5 serves as a bearing for the valve stem in block 42 as shown.

In accordance with the invention the movement of valve stem to and from the various positions described is brought about through manipulation of treadle l6, and the operating connections between these two parts are shown most clearly in Figs. 3 to 5. The treadle is secured to a shaft to carried by trunnion members 8! and 82 extending downwardly irom the bottom of casing 30. The outer end 01 valve stem 15 is provided with a pair or collars 83 one on each side of a yoke ll which is also secured to shaft 80. These connections are such that downward movement of the treadle- I! will cause the valve stem I! to slide forward into the cylinder block and move the valve portions thereof from open to closed position with respect to bore 86. A coil spring I! is mounted on shaft an in such position as to raise the treadle and return the valve stem and its valve portions to the open position when the treadle is released. These parts are covered in use by a shield 38, which is shown in Figs. 1 and 3 but is broken away in Fig. 2.

In the operation of the system, the normal position of the parts is as shown in Figs. 2 and 4, with valve stem IS in such position that its valve portion 'l'l of reduced diameter is in register with bore 86 to permit continuous circulation of the fluid 50 through these bores, by-passing cylinder 4 l. Under these conditions, clamp member I! is held in its uppermost position by its counterbalance mechanism, thus holding arm 35, lever 33 and piston 40 in their uppermost positions as shown in Fig. 2. When it is desired to operate the clamp mechanism, treadle i5 is depressed against the action or spring 86, and valve stem-ll slides inwardly until its valve portion 18 closes bore 68. Since pump Si is operating continuously, this will iorce the fluid from its discharge line I to enter cylinder 41 through bore 10 and opening H and thereby increase the pressure within the cylinder sufllciently to move piston 40. The piston will accordingly move downwardly as shown in Fig.0, and will thereby force lever 38 to swing about its pivot 34 and to draw down arm 35 and the clamp member It as indicated in dotted lines it is merely necessary to remove pressure from will thus draw arm 35, lever 33 and piston 40 back again to their uppermost positions.

In order to avoid development 0! excessive pressure when the piston and clamp are. prevented i'rmn moving by engagement with the work, which position it may be desirable to retain for a period 0! time, a relief valve is provided within the cylinder block. As shown in Figs. '4 and 8, a bore connects bores l8 and I, and its connection with bore I. is controlled by a ball valve ti and spring 92. This spring may be set for a predetermined pressure, ior example 400 pounds per square inch, and when the pressure within the cylinder reaches this value, the spring will be overcome to permit the fluid to resume circulation through bores 8, l0 and 88 while still maintalning the clamp in clamping position. With a piston of a diameter of 1 inches, this construction will provide a force oi 700 to 750 pounds eflective on lever 33 and a net pressure available on the pile ofv between 200 and 250 pounds, as compared with full clamping pressure of the order of one or more tons exerted during the cutting cycle of the machine.

The above construction provides also for controlling the rate at which the clamp member moves as well as for stopping it in any desired position and controlling its pressure within the maximum range determined by the setting of the spring I: for the relief valve. Thus, if valve stem II is moved in only part way, such that the slotted valve portion I8 is in register with bore #6, the pressure within cylinder 4| may be regulated to provide for slow movement of the piston in either direction or for stopping the piston and clamp in any desired position, by adjustment of the valve, such that the fluid escapes through slots 18 at a pressure just equal to the pressure of the counterbalance for the clamp member. Similarly, when the clamp is restrained from moving, the pressure exerted thereby maybe varied by adiustment oi the valve to permit slow escape of fluid through slots 18 at a rate such that the pressure is maintained below the maximum at which the relief valve in bore on will open. Thus by variation of the position of the valve stem 15 under control of the treadle, the effective pressure of the clamp on the pile, as well as its upward and downward movement, are under continuous and accurate control.

The invention accordingly provides for the simple and eflective movement or the clamping mechanism of a paper cutting machine with minimum physical effort on the part of the operator. The above described and illustrated hydraulic system provides both for movement of the clamping mechanism independently of the main operating mechanism of the machine and also for full control and adiustmentoi the clamping mechanism, including stopping and starting at any point, direction of movement and degree 0! pressure exerted. This control and adjustment is obtained in accordance with the invention by simple manipulation of the treadle, which requires no greater force than is necessary to overcome the spring pressure returning the treadle to'its inoperative position when released, there being substantially no resistance to the movement of the valve controlling the flow or hydraulic fluid as described in response to treadle movement. Accordingly the physical efl'ort required on the part or the operator may be considered as virtually negligible, particularly as compared with the corresponding effort needed for'operation of the clamp member by mechanical connection with the treadie, which in addition does not aflord comparable flexibility or control.

1 While the form of apparatus herein described constitutesa preferred embodiment oi the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and

. inary operation of said clamp member independently of the main operating mechanism of said machine and comprising, in combination, 9, cylinder and piston mounted for relative movement in response to fluid pressure within said cylinder, means efl'ective upon relative movement of said of said fluid therethrough and being effective in another position to close said Icy-pass and to supply said fluid under pressure to said motor, and means limiting the maximum fluid pressure supplied to said motor.

4. In a cutting machine of the character described having a clamp member for clampin work material to be cut and for gauging the out line on said material, means for the preliminary operation of said clamping member independently oi! the main operating mechanism 01' said machine and comprising, in combination, a fluid pressure motor mounted on said machine, means providing a connection between said motor and piston and cylinder to cause clamping movement of said clamp member, means for providing a supply of hydraulic fluid under pressure, means forming a passage for supplying said pressure fluid to said cylinder, means forming a by-pass passage for said fluid by-Dassing said cylinder, valve means controlling the flow of said pressure fluid through said by-pass, means limiting the maximum pressure developed within said cylinder, and externally operable means controlling the movement of said valve means.

2. In a cutting machine of the character described having a clamp member for clamping work material to be cut and for gauging the cut line on said materiaL-means for the preliminary operation of said clamping member independently of the main operating mechanism or said machine and comprising, in combination, a cyl-- inder and piston mounted for relative-movement in response to fluid pressure within said cyilnder,

means effective upon relative movement of said piston and cylinder to cause clamping movement of said clamp member, means for containing a supply 01 hydraulic fluid, means forming a pas- ,sage for conveying said pressure fluid to said cylinder,v means forming a by-pass passage for said fluid by-passing said passage to said cylinder, mean providing for the circulation of said fluid under pressure through said passage, valve means controlling the relative flow of said fluid to said cylinder and through said by-pass, means limiting the maximum pressure developed within said cylinder, and externally operable means controlling movement of said valve means.

3. In a cutting machine of the character describedhaving a clamp member for clamping work material to be cut and for gauging the out line on said material, means for the preliminary operation of said clamping member independently of the main operating mechanism of said machine and comprising, in combination, a fluid pressure motor, means providing a connection between said motor and clamp member eflectlve to cause clamping movement of said clamp member upon the application of fluid pressure to said motor, means for containing a supply of hydraulic fluid, means forming a passage for supplying said pressure fluid to said motor, means forming a by-pass passage for said fluid bypassing said passage to said motor, means providing for the circulation of said fluid under pressure through said passages, valve means controlling the relative flow of said fluid to said motor and through said by-pass, externally operable means controlling movement of said valve means, said valve means being effective at one position to open said by-pass for continuous circulation said clamp member effective to cause clamping movement of said clamp member in response to the application of pressure to said motor, means for containing a supply or hydraulic fluid, means forming a passage for supplying said pressure fluid to said motor, means forming a by-pass passage for said fluid by-passing said passage to said motor, means providing for the circulation of said fluid under pressure through said passages, valve means controlling the relative flow of said fluid to saidmotor and through said by-pass. and externally operable means controlling movement 01' said valve means, said valve means being effective in one position to open said by-pass for continuous circulation of said fluid therethrough and being. eflective in another position to close said by-pass and to simply said fluid under pressure to. said motor, said valve means being effective in a third position to open said by-pass partially Ior restricted passage of said fluid therethrough.

5. In a cutting machine of the character described having a clamp member for clamping work material to be cut and for gauging the out line on said material, means for the preliminary operation of said clamping member independently oi .the main operating mechanism of said ma- I chine and comprising, in combination, a fluid pres-sure motor, means providing-a connection between said motor and said clamp member efl'ective to cause clamping movement of said clamp member in response to the application of fluid pressure to said motor, means for containing a supply of hydraulic fluid, means forming a passage for supplying said pressure fluid to said motor, means forming a by-pass passage for said fluid by-passing said passage to said motor, means providing for the circulation or said fluid under pressure through said passages, a valve mounted for sliding movement substantially transverse to said by-pass to control the flow of said fluid therethrough, said valve being effective in one position to open said by-pass for the continuous circulation of said fluid therethrough and being effective in another position to close said by-pass and to supply said fluid under pressure to said motor, and means limiting the maximum fluid pressure supplied to said motor.

6. In a cutting machine of the character described having a clamp member for clamping work material to be cut and for gauging the cut line on said material, means for the preliminary operation of said clamping member independently of the main operating mechanism of said machine and comprising, in combination, a cylinder and piston mounted for relative movement in response to fluid pressure within said cylinder, means effective upon relative movement of said piston and cylinder to cause clamping movement of said clamp member, means for containing a supply of hydraulic fluid, a pump having its intake adapted for connection with such supply or fluid, means forming apassage leading trom the outlet or said pump/intosaid supply of fluid and providing for continuous circulation thereof, a valve control-' said pump for-supplying said fluid to said cylinsition to der, said valve being eflective in one open said passage for continuous circ on of said fluid therethrough under the action said pump and being eflective in another position to close said by-passv and thus to cause said fluid to enter said cylinder under action or said pump, pressure relief means for preventing the pressure within said cylinder from exceeding a predetermined maximum, and externally operable means controlling movement or said valve.

"I. In a cutting machine oi the character described having a clamp member for clamping work material to be cut and for gauging the cut line on said material, means tor the preliminary operation ,or said clamping member independently or the main operating mechanism of said machine and comprising, in combination, a cylinder and piston mounted for relative movement in response to fluid pressure within said cylinder, means effective upon relative movement of said piston and cylinder to cause clamping movement of said clamp member. means for containing a supply of hydraulic fluid, a pump having its intake adapted for connection with such sup ply of fluid, means forming a passage leading from the outlet of said pump, back to said supply of fluid and providing for the continuous circulation thereof, a valve for controlling the flow of liquid through said passage and mounted for sliding movement at an angle to said passage, a connection between said passage and; said cylinder positioned between said valve and the outlet said pressure fluid through said by-pass, said valve means being eflective in one position to open said by-pass tor the passage of said fluid therethrough and being effective in another position to close said by-pass and to cause said mud to" enter said cylinder and to move said piston therein.

,9'. In a cutting machine of the character. described having' a clamp member ior clamping work material to be cut .and ior gauging'the out line on said material. means for the preliminary operation of said clamping member independently or the main operating mechanism 01' said machine and comprising, in combination, a. cylin-, der, a piston mounted for movement in said cylinder in .response to fluid pressure therewithin,"

means including a lever for "causing operative movement of said clam'p member, means mounting said lever for pivotal movement in the plane of motion or said piston and adjacent thereto, roller means carried by said lever and engage able by said piston upon motion thereof in said cylinder to cause pivotal movement'oi said lever, means for containing a supply or hydraulic fluid, means iorming a passage for conveying said pressure fluid to said cylinder, means forming a bypass passage for said fluid by-passing said passage to said cylinder, means providing for the circulation of fluid from said container under pressure through said passages, and a valve consaid by-pass and to cause said fluid to enter said of said pump for supplying said fluid to said cylinder, said valve being eflective in one position to open said passage for continuous circulation or said fluid therethrough and in another position to close said passage and thus to cause said fluid to enter said cylinder under the action of said pump, said valve in an intermediate position being effective to open said passage partiall for restricted circulation or fluid therethrough to establish an intermediate pressure within said cylinder for con-trolling the operation of said pump, and pressure relief means for preventing the pressure within said cylinder'from exceeding a predetermined maximum.

8. In a cutting machine of the character described having a clamp member for clamping work material to be cut and for gauging the out line on said material, means for the preliminary operation of said clamping member independently of the main operating mechanism of said machine and comprising, in combination, a cylinder,

' a piston mounted for movement in said cylinder cylinder under pressure and to bring about movement of said piston and lever, said valve in an intermediate position being eflective to open said by-pass partially for restricted passage or said fluid therethrough to establish an intermediate pressure within said cylinder to control the oper ation of said clamp.

10. In a cutting machine or the character described having a clamp member for clamping work material to be cut and for gauging the cut line on said material, means for the preliminary operation of said clamping member independently of the main operating mechanism of said machine and comprising, in combination, a fluid pressure motor, means providing a connection between said motor and said .clamp member eftective to cause clamping movement 01 said clamp member upon the application of pressure fluid to said motor, means for containing a supply or hydraulic fluid, a pump having its intake positioned for connection with such supply of fluid, means forming a passage leading from the outlet of said pump back to said container for fluid and providing for continuous circulation of fluid, said passage including'two angularly arranged connecting portions, a valve mounted for sliding movement in one of said angularly arranged pas sage portions adjacent the Junction between said portions, a connection between said passage and said motor positioned between saidvalve and the outlet of said pump'for supplying said pressure fluid to said motor, means limiting the maximum fluid pressur supplied to said motor, said valve including portions of different cross-sectional area and being effective in one position to close communication between said angularly arranged passage portions to supply said fluid to said motor under the action of said pump, said valve being effective in another position to open said pas- 11' sage for continuous circulation of said fluid therethrough.

11. In a cutting machine of the character described having a clamp member for clamping work material to be cut and for gauging the out line on said material, means for the preliminary operation of said clamping member independently of the main operating mechanism of said machine and comprising, in combination, a cylinder and piston mounted for relative movement in response to fluid pressure within said cylinder, means for containing a supply of hydraulic fluid, a pump having its intake positioned for connection with such supply of fluid, means forming a passage leading from the outlet of said pump back to said container for fluid and providing for continuous circulation of fluid, said passage including two angularly arranged connecting portions, a valve mounted for sliding movement in one of said angularly arranged passage portions adjacent the Junction between said portions, a connection between said passage and said cylinder positioned between said valve and the outlet of said pump for supplying said pressure fluid to said cylinder, said valve including portions of diflerent cross-sectional area and being effective in one position to close communication between said angularly arranged passage portions to cause said fluid to enter said cylinder under the action of said pump, means limiting the maximum pressure developed within said cylinder, said valve being eilectivein another position to open said passage for continuous circulation of said fluid therethrough, said valve in an intermediate position being effective to permit restricted circulation of said fluid through said passage.

12. In a cutting machine of the character described having a clamp member for clamping work material to be cut and for gauging the out line on said material, meansfor the preliminary operation of said clamping member independently oi' the main operating mechanism of said machine and comprising, in combination, a casing secured to said machine and adapted to contain a supply of hydraulic fluid, means providing a cylinder carried by said casing, a piston mounted in said cylinder for relative movement in response to fluid pressure within the cylinder, pressure relief means for preventing the pressure within said cylinder from exceeding a predetermined maximum, a pump having its intake connected with said supply of fluid, means forming a passage leading from the outlet of said pump back to said supply of fluid within said casing and providing for continuous circulation of said fluid, a valve controlling the flow of said fluid through said passage, means providing a connection between said cylinder and said passage positioned between said valve and the outlet oi said pump, said valve being effective in one position to close said passage to cause said fluid to enter said cylinder under the action of said pump and being effective in another position to open said passage for continuous circulation of said fluid therethrough, a lever pivotally secured to said casing for swinging movement about a substantially horizontal axis, and an arm connected at one end to said lever and at the other end to said clamp member for moving said clamp member vertically in response to swinging motion of said lever, said lever being positioned for operative engagement with said piston and being adapted to be swung downwardly upon movement of said piston in response to fluid pressure within said cylinder.

13. A servo mechanism for operating the mo able clamp member of a paper cutting machine, comprising, in combination, a fluid pressure motor mounted on said machine, means providing a connection between said clamp member and said motor effective to cause clamping movement of said clamp member upon the application of pressure fluid to said motor, means for containing a supply of hydraulic fluid, means including a pump and a passage by-passing said motor for circulating fluid from said container, a valve controlling the flow of said fluid through said bypass, means forming a passage connecting said motor with said by-pass and opening into said bypass at a position between said valve and the outlet of said pump, said valve being efiective in one position to open said by-pass for continuous circulation of said fluid therethrough and being effective in another position to close said bypass and to cause said fluid to be supplied to said motor under the action of said pump, and means limiting the maximum fluid pressure supplied to said motor.

14. In a paper cutting machine of the charac-,

ter described, the combination of a work table, a, clamp member mounted for relative movement with respect to said work table for clamping work material to be cut, a casing mounted on said machine at a position below said work table, a cylinder within said casing, a piston mounted for relative vertical movement in said cylinder in response to fluid pressure within said cylinder, means including a lever providing a connection between said piston and said clamp member effective to cause clamping movement of said clamp member upon outward movement or said piston from said cylinder, said connection means being independent of the main' operating mechanism oi. said machine, said casing being adapted to contain a supply of hydraulic fluid, a pump mounted within said casing, means including a passage icy-passing said cylinder and cooperating with said pump for circulation of said fluid within said casing, means forming a passage for supplying said fluid to said cylinder, relief valve means for controlling the pressure developed within said cylinder, valve means controlling the relative flow of said fluid through said passage and said by-pass, and externally operable means controlling the movement of said last named valve means.

15. In a paper cutting machine of the character described having a work table and a clamp member mounted for relative movement with respect to said work table for clamping work material to be cut,- operating means for said clamp member comprising, in combination, a casing adapted to be mounted on said machine, a fluid pressure motor within said casing, said casing being adapted to contain a supply of hydraulic fluid for operating said motor, means providing a connection between said motor and said clamp member eiTective to cause clamping movement of said clamp member upon the application of pressure fluid to said motor, means within said casing for supplying such hydraulic fluid under pressure to said motor, control means for regulating the flow of such fluid to said motor, means limiting the maximum fluid pressure supplied to said motor, and externally accessible means carried by said casing for actuating said control means for the operation of said clamp member.

WILLIAM R". SPILLER.

. A Gertlleate of Correction 7 Patent No. 2,445,248. July 13, 1948. WILLIAM .R. SPILLER It ishereby certified that errors appear in the printed specification of the above numbered patent reqluniring correction as follows: Column 7, line 46, claim 2, for mean read means; e 47, for passage read. panties and that the said Letters Patent should be read with these corrections therein at the sanre may conform to the record of the case in the Patent Oflice Signed and sealed this 26th day of Oetobenh. D. 1948.

I THOMAS F. MURPHY, I

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