US1913663A - Percussion press - Google Patents

Description

June 13, 1933. w. FERRIS PERCUSSION PRESS 1930 4 Sheets-Sheet 3 Fil'ed Dec. 15

h m vv om. nm Nm H R E F H E U Patented June 13, 1933 UNITED STATES PATEur F'FIE WALTER FEBRIS, OF MILWAUKEE, WISCONSIN, ASSIGNOE TO THE OILGEAR COMPANY, OF MILWAUKEE, WISCONSIN, A COB-PORATIOE' OF WISCONSIN rnacussroir ranss Application filed December 15, 193G. Serial No. 502,40l..-

This invention relates to percussion presses of that type in which energy is stored in a flywheel and then transmitted to the rain through a screw. v

The prior p'resses of this character had the flywheel rigidly secured to the power screw and rotated mechanically by power applied to its periphery, and the flywheel had to be rotated during both the power and the return strokes of the ram.

'An object of the invention is to provide a percussion press which is operated hydrauli call A hOther object is to retract the ram without rotating the flywheel.

Another object is to provide a hydraulically operated press in which the speed of the flywheel is accelerated as themam approaches the work.

Another object is to provide a percussion press which is susceptible of close control and adjustment.

Another object is to provide a hydraulically operated flywheel press having an automatic control.

According to one aspect of the invention, the press is operated by a hydraulic motor which has its displacement reduced as the ram advances to thereby progressively. increase the speed of the flywheel and to utilize as nearly as possible the full power of the pump.

According to another aspect of the invention, the flywheel is fixed for rotation with the screw and has energy stored therein during the power stroke of the press and is disengaged therefrom during the idle stroke of the press to. enable the screwv to rotate without Fig. l is in part a front elevation and in part a central section of a press in which the invention is embodied.

Fig.2 is a side elevation thereof.

Fig. 3 is a bottom plan view of certain details, taken on a line 33 of Fig. 1.

Fig. 4 is a schematic drawing of the hydraulic circuit and shows the several valve plungers in the positions occupied when the press is idle.

Fig. 5 is a longitudinal section through the maincontrol valve and shows its plunger in the position occupied when the ram is being advanced.

Fig. 6 is a longitudinal section through the main control valve and shows its plun er the position occupied when the ram isieing retracted.

Fig. 7 is a longitudinal section through a bypass or high speed valve and shows its plunger in the position occupied when liquid is being bypassed from one end of the motor cylinder to the other end thereof to advance the ram at high speed.

Fig. 8 is in part a central section through a modified form of hydraulic motor and in part a schematic drawing or a hydraulic circuit in which the motor is connected.

Figs. Ito '7 I The press comprises, in general, a frame 1 which carries a stationary impact member or die 52 for supporting the work, a ram '3 which carries a movable impact member or die 4 through which impacts are delivered to the work, a power screw 5 for advancing and retracting the ram 3 toward and from the work, a hydraulic motor 6 for operating the screw 5., and a flywheel? in which energy is stored as the ram 3 is being advanced.

The frame 1 has a lower opening 8 and an upper opening 9 formed therein and sep arated from each other by a nut 10 having a vertical threaded bore 11 through which the screw 5 is threaded. The nut 10 is secured rigidly in position, as by means of a supporting bar 12 arranged upon each side there- .of and securely fastened to the nut 10 and the frame 1.

The lower opening 8 has the stationary die 2 arranged therein and secured in a fixed position upon the bottom thereof, and it has the ram 3 arranged therein for reciprocation between its vertical side walls which are 5 parallel to each other and provided with guides 13 for holding the ram 3 against rotative or lateral movement.

The ram 3 is pivotally secured to the screw 5 by a retaining plate 14 which is attached to the top of the ram 3 and encircles the screw 5 between its threaded part and a cylindrical head 15 formed upon its lower end, and the head 15 is arranged in a complementary recess 16 formed in the top of the 5 ram 3.

29 the work.

' The upper end of the screw 5 has a toothed clutch disk 17 secured thereto or formed integral therewith for cooperating with a complementary toothed disk 18 which is secured to or formed integral with the flywheel 7.

The disks 1? and 18 constitute the two halves of a jaw clutch and are arranged in a cylindrical recess 19 which is formedin the underside of the flywheel 7. A retaining plate 20 is secured to the underside of the flywheel 7 and encircles the screw 5 between its thread and the disk 1? to cause the screw 5 to move upwardly with the flywheel 7, and the recess 19 is deep enough to allow the teeth on the clutch disks 1? and 18 to separate when the flywheel 7 is drawn upwardly. Also, an anti-friction bearing 21 is ordinarily arranged between the disk 17 and the retaining plate 20.

The flywheel 7 has a cylindrical recess 22 formed in its upperside and ordinarily provided with an anti-friction bearing 23 to receive the thrust ofthe hydraulic motor 6 which has its cylinder secured to the top of the frame 1 and the rod 24 of its piston 25 provided with a circular abutment 26 to enga e the hearing 23.

The abutment 26 is arranged in the recess 22 and retained thereinby a retaining plate 27 which is secured to the flywheel 7 and fixes it for axial movement with the piston rod 24.

When liquid is supplied to the upper end of the motor 6 to move the piston 25 downwardly, the clutch disk 18 engages the clutch disk 17 and the teeth thereon interlock and the pressure exerted by the liquid upon the piston 25 tends to force the screw 5 axially through the nut 10.

The thread of the screw 5 has a steep pitch and the thrust of the motor 6 causes it, to rotats and thereby impart rotation to the flywheel 7, and the speed of the flywheel in creases as it continues to rotate and move downwardly.

Energy is thus stored in the flywheel 7 and the motor 3 continues to store energy therein until the ram 3 stalls at the bottom of its stroke, as by the die 4 engaging a piece of work carried by the die 2, and then substantially all of the energy stored in the flywheel 7 is suddenly dissipated through the screw 5 and the ram 3 and absorbed by the work.

When the motor 6 is reversed, the clutch disks 17 and 18 separate, the screw 5 is drawn upwardly through the nut 10 and caused to rotate as it passes therethrough, and the antifriction bearing 21 enables the screw 5 to rotate Without material tendency to rotate the flywheel 7 against its inertia.

Consequently, the ram 3 may be raised at a higher speed and with a smaller expenditure of energy than is possible Wlltfil the flywheel rotates ring its upward movement.

The motor 6 is operated by liquid supplied from a pump 28 which preferably delivers liquid at a constant predetermined pressure.

That is, after the pump has been adjusted to determine the maximum hydraulic pressure which it can create, it delivers liquid at its full adjusted capacity until the pressure reaches the predetermined maximum and then it maintains that pressure substantially constant.

The pump 28 has not been'illustrated nor described in detail herein as a pump which may be employed is disclosed in Patent Numher 1,775,613 issued September 9, 1930 to John P. Ferris.

The output of the pump 28 is delivered into a supply pipe 29 which is connected to a port 30 formed in the cylinder 31 of a control valve 32, and liquid is returned to the pump 28 through a return pipe 33 which has one of its ends connected to the intake of the pump 28 and its other end connected to both ends of the cylinder 31.

The return pipe 33 is connected by a pipe 34 to both ends of a pump bypass valve 35 to hydraulically balance its plunger 36 which controls a p0rt37 connected by a pipe 38 to the supply pipe 29..

The plunger 36 normally closes the port 37' but, when the press is idle and the pump 28 is running, it may be moved to the left and allow the liquid delivered by the pump 28 to bypass freely through the pipes 29 and 38,

the valve 35 and the pipes 34 and 33 to the pump intake.

The control valve 32 has a port 39, which is connected by a pipe 40 to a port 41 formed in the cylinder 42 of a motor bypass or high speed valve 43, and a port 44 which is connected by a pipe 45 to the upper end of the motor 3 and by a pipe 46 to a port 47 in the high speed valve 43. The ports 39 and 44 are normally closed by a valve plunger 48 which has a small piston 49 secured to its rear end ranged intermediate the ports 41 and 47 and connected by a pipe 53 to the lower end of the motor 6, and it has each end of itscylinder 42 connected to a drain pipe 54 which discharges into the reservoir of the pump 28.

The ports 41 and 47 are closed alternately by a valve plunger 55 which has a stem 56 secured to its front end and a small piston 57 of the same diameter as the stem 56 secured to its rear end. The stem 56 extends ends to the supply pipe 29 through a high pressure resistance valve 62and has one of its ends connected to the rear end of the cylinder 50 on the control valve 32 and its other end connected to a port 63 in a drain valve 64 which is open at both ends to the dra n pipe 54.

The port 63 is normally open to the drain pipe 54 and is controlled by a valve plunger 65 which is urged to its neutral or open position by a helical compression spring 66 and has its stem 67 provided upon its outer end with a bevel faced cam 68.

The valves 43 and 64 are operated, respectively, by two valve actuators 69 and 70 which have their under faces beveled to enthe outer end of an arm 73 which extends other end secured in an adjusted position upon the piston rod 24 of the motor 6. The position of the arm 73 on the rod 24 determines the length of the press stroke.

The actuator 69 is secured to the rod 71 H1 position to engage the cam 58 and force the valve plunger 55 to the position shown 1n Fig. 7 when the piston 25 has moved downwardly a predetermined distance, thereby opening theport 52 to the port 47 to bypass the liquid from the exhaust end of the motor 6 to the pressure end thereof and accelerate the speed of the piston 25. The liquid in the cylinder 60 is exhausted through the pipe 61 and the drain valve 64 into the drain pipe 54. The downward movement of the piston rod 24 carries the actuator 69 below the cam 58 and the valve plunger 55 is returned to its initial position when the press completes its power stroke. During the return stroke of the press, the actuator 69 engages the cam 58 and swings it upon its pivot and then the cam 58 falls against the stop 59 after the actuator 69 has passed.

The actuator 70 is secured to the rod 71 in position to engage the cam 68 and urge the valve plunger 65 rearwardly just before the ram 3 reaches the limit of its power stroke so that the port 63 in the valve 64 will be completely closed when the ram 3 stalls. Closing the port 63 allows the plunger 55 of the valve 43 to be returned hydraulically to its initial position and the valve 32 to be operated hydraulically to reverse the motor 6.

The control valve 32 is operated mechanically through a control rod 75 consisting of a lower rod section 76 and an upper rod section 77 connected to each other by a caged spring 78 which allows relative movement between the two rod sections.

The lower section 76 (Fig. 1) is connected to the stem 51 of the valve 32 and the upper section 77 is connected to one end of a lever 79 which has its other end fixed upon a shaft 80 journaled in two brackets 81 and 82 carried by the top of the frame 1.

A lever 83 is also secured upon the shaft 80 at an angle to the lever 79 and has its free end pivoted to a control rod 84 which passes through a guideway' 85 in the to of the frame 1 and extends into the path 0 the arm 73 so that, as the piston 25 approaches the limit of its upward stroke as determined by the position of the arm 73 upon the piston rod 24, the arm 73 engages the rod 84 and moves it upwardly and thereby swings the levers 83 and 79 to move the rod 75 axially and move the valve plunger 48 to the position shown in Fig. 4.

The control valve 32 is operated manually to start the press by means of a foot lever 86 which is pivoted at one end to a stationary bracket 87 and urged upwardly at its free end by aspring 88.

The lever 86 is connected intermediate its ends by a connecting rod 89 to a trip lever 90 which is pivoted at one end upon a pin 91 carried by the bracket 81 and has its other end arranged in alinement with the horizontal arm of a bell crank lever 92 journaled on the shaft 80. The vertical arm of the lever 92 is urged by a spring 93 against a sto 94 which is carried b the shaft 80 and xed for rotation therewith.

When the foot lever 86 is depressed against the action of the spring 88, the connecting rod 89 swings the trip lever 90 against the bell crank lever 92 and rotates it and thereby rotates the stop 94 and the shaft 80 to swing the lever 79 and thus move the valve plunger 48 to the position shown in Fig. 5.

Depressing the foot lever 86 moves the free end of the trip lever 90 below the horizontal arm of the bell crank lever 92 and, if the foot lever 86 is held down until the press completes a cycle of operation and the bell crank lever 92 has been returned to its initial position by the stop 94, and the lever 86 is then released to allow the spring 88 to raise the lever 86 and the rod 89 to their initial positions, the trip lever 90 will rotate the bell crank lever 92 on the shaft 80 and then the spring 93 will retract the bell crank lever 92 to its initial position after the trip lever 90 has moved above it.

The valve 32 may beoperated manually at any time to start, stop or reverse the press by means of a hand lever 95 which is pivoted at one .of its ends to the lower section 76 of the control rod and pivoted intermediate its ends upon a bearing 96 carried by the frame 1, the caged spring 78 allowing the plunger 48 to be moved in either direction without affecting the mechanism which is connected to the rod section 77.

Assuming that the pump 28 is running and that the plunger 36 of the bypass valve 35 has been moved to the position shown in Fig. 4 to close communication between the supply pipe 29 and the return pipe 33, the operation of the press is as follows:

The foot lever 86 is depressed to operate the valve control mechanism and move the plunger 48 of the control valve 32 to the position shown in Fig. 5, as previously described.

The pump 28 then delivers driving liquid through the pipe 29, the valve 32 and the pipe 45 to the head end of the motor 6 to force its piston 25 downwardly and engage the clutch disk 18 with the clutch disk 17, and liquid is exhausted from the gland end of the motor 6 through the pipe 53, the bypass valve 43, the pipe 40 and the valve 32 to the return pipe 33. The driving liquid delivered to the motor 6 acts upon the full area of the piston 25 and forces the screw 5 through the nut 10 and causes it and the flywheel 7 to rotate and move downwardly A relatively large force is required to overcome the inertia of the flywheel 7 and the screw 5 and cause the same to move downwardly and rotate but a decreasing amount of force is required after the flywheel attains speed. p

In order to obtain the greatest eficiency from the press, the power stroke should be made in the least possibletime and the dywheel accelerated as much as possible before the die strikes the work.

The pump 28 has automatic stroke control mechanism incorporated therein which is responsive to the pressure created by the pump and which may be manually adjusted to cause the pump to maintain any predetercourse, dependent upon the resistance encountered by the driving liquid, and the pump will deliver liquid at its full volumetric capacity until the pressure created by it reaches the predetermined pressure and then it will deliver just enough liquid to maintain that pressure constant.

When the press is idle, the pump cannot deliver any liquid but it creates the predetermined pressure in the discharge pipe and then the stroke control mechanism reduces the stroke to zero or until the pump is delivering only the small quantity required to compensate for slip or leakage.

When the control valve 32 is opened, the pressure drops momentarily and the pump increases its stroke until the liquid encounters the resistance of the flywheel and the pressure again rises and reduces the stroke until the pump is delivering only that volume required to maintain the predetermined pressure.

This pressure, acting upon the piston 25, overcomes the inertia of the flywheel 7 and starts the press upon its power stroke, and the pump 28 automatically increases its stroke to supply liquid'to the motor 6 in sufficient volume to maintain the pressure therein substantially constant. I

The flywheel is thus started and then gradually-but positively accelerated by a force which is maintained constant until the pump reaches its full volumetric capacity.

If the pump could operate at full volumetric capacity and at full pressure during the entire power stroke and if the displacement of the motor could be progressively reduced as the flywheel accelerates to en able the pump to progressively increase the speed of the flywheel at a rapid rate, the maximum amount of energy could be stored in the fiywheel to be dissipated through the ram to the work at the end of the power stroke.

As the flywheel cannot be started instant-- ly, this result cannot be fully realized but it may be closely approximated by making the displacement of the motor as large as possible to enable the pump to start the flywheel, then increasing the delivery of the pump to full volume, and then decreasing the displacement of the motor to enable the pump to accelerate the flywheel.

The effective area of the piston 25 is made as large as is practically possible and the liquid acts thereon to advance the screw 5 and start the flywheel 7 and it continues to act thereon until the flywheel 7 has attained a predetermined speed or until the pump 28 has reached substantially its full volumetric capacity.

Then the efiective area of the piston 25 is reduced by the actuator 69 engaging the cam 58 and operating the high speed valve 43 to bypass liquid from the exhaust end of the 5 motor 6 to the pressure end thereof through the pipe 53, the valve 43 and the pipes 46 and 45 Bypassing liquid from the exhaust end of the motor cylinder to the pressure end there- 10 of has the eflect of reducing the displacement of themotor 6 so that only a volume of liquid corresponding to the displacement of the piston rod 24 is now required. The pump 28 automatically reduces its output to conform to this requirement and then gradually increases its output as the flywheel accelerates.

However, the driving liquid is capable of exerting upon the effective pressure area of the piston 25 a force which is sufiicient to continue to accelerate the speed of the flywheel 7 and the pump increases its output as the flywheel accelerates. When the die 4 en- I gages the work, substantially all of the energy stored in the flywheel is transmitted thereto through the screw 5.

The displacementof the motor 6 is reduced but once by bypassing liquid from one end of the motor cylinder to the other end thereof but it may be reduced as many times as is 39 necessary to progressively accelerate the flywheel during the entire working stroke, for instance by employing a composite piston such as that shown in Fig. 8, the number of reductions depending upon the length of the stroke and the volumetric capacity of the Just before the die 4 stalls against the work, the actuator 7 engages the cam 68 and closes the drain valve 64. When the die 4 stalls, pressure rises in the supply pipe 29 and liquid breaks through the resistance valve 62 into the pipe 61 and the cylinders and to act upon the pistons 49 and 57 and force the valve plunger 48 to the position shown in Fig. 6 and the valve plunger 55 to its initial position.

The pump 28 now delivers driving liquid through the pipe 29, the valve 32, the pipe 40, the valve 43 and the pipe 53 to the lower end of the motor 6 and reverses it, and liquid is exhausted from the upper end of the motor 6 through the pipe 45 and the valve 32 to the return pipe 33.

5 q The press now starts the return stroke, the

' actuator 70 disengages the cam 68 and the spring 66 opens the drain valve 64, the actuator 69 swings the cam 58 upon its pivot when passing it and then the cam 58 falls back 50 against the stop 59, and the arm 73 then engages the rod 84 and. operates the valve control mechanism to return the valve plunger 48 to its initial position.

" The press is now at rest and ready to start a second cycle of operation.

Fig. 8

The motor shown in this figure has a composite piston 97 fitted in its cylinder 98 and comprising a number of concentric annular sleeves fitted one within the other and a solid piston '99 which is fitted in the innermost sleeve and secured to the connecting rod 24 of a press such as that shown in Fig. 1.

The piston 99 is shown provided with but two sleeves 100 and 101 in order to avoid complications of detail but it may be provided with any number of sleeves depending largely upon the capacity of the pump and the stroke of the press.

The sleeve 100 is fitted in the cylinder. 98 and provided at its upper end with a flan e 102 and at its lower end with a removab e annular plate 103 for retaining the sleeve 101 therein.

The sleeve 101 is fitted in the sleeve 100,

and the piston 99 is fitted in the sleeve 101 and retained therein by a flange 104 extending around the u per end of the sleeve 101 and by a remova le plate 105 which is attached to the lower end of the sleeve 101.

This motor is employed on the press in exactly the same manner as the motor 6 and it is shown connected into a. hydraulic circuit which is the same as the circuit shown in Fig. 4 except that the bypass valve 43 and the pipes 46 and 53 have been omitted and the pipe 40 connected directly to the lower end of the motor. Consequently, like parts have been indicated by like reference numerals.

When the control valve 32 is operated to start the press, liquid flows from the pump 28 through the pipe 29, the valve 32 and the pipe 45 to the upper end of the cylinder 98 and acts upon combined areas of the piston 99 and the sleeve 100 and 101 to force them downwardly and thereby impart axial and rotative movements to the screw 5 and the flywheel 7. The liquid in the lower end of the cylinder 98 is exhausted through the pipe.

40 and the valve 32 to the return pipe 33.

As the flywheel starts to rotate, the hydraulic pressure drops slihtly and the pump increases its stroke gra ually and thereby gradually increases the speed of the flywheel.

. When the sleeve 100, which is longer than the sleeve 101, stalls against the bottom of r the cylinder 98, the displacement of the motor is reduced and the pressure rises and causes the pump to shorten its stroke.

J The liquid now acts upon the combined areas of the piston 99 and the sleeve 101 and, as the flywheel continues to move downwardly, the pressure again drops slightly and the pump again gradually increases its stroke to thereby gradually accelerate the flywheel.

still more.

When the sleeve 101, which is longer than the piston 99, stalls against the bottom of the cylinder 98, the displacement of the motor is still further reduced and the pressure rises and causes the pump to again shorten its stroke.

The liquid now acts upon the piston 99 only and, as the flywheel continues to move downwardly, the pressure drops slightly and the pump gradually increases its stroke to further accelerate the flywheel.

The motor displacement is thus progressively reduced as the flywheel advances and the pump is enabled to accelerate the flywheel to a relatively high speed and store a large amount of energy therein.

en the ram stalls against the work, the valve 32'is reversed. as previously described and liquid flows from the pump 28 through the pipe 29, the valve 32 and the pipe to the lower end of the cylinder 98 to raise the piston 99 and the sleeves 1G0 and 101, and liquid is exhausted from the upper end of the cylinder 98 through the pipe and the valve 32 to the return pipe 33.

A press constructed according to the present invention is suitable for hot d1e pressing articles from non-ferrous metals, for hot or cold pressing of steel parts, for pressing plastic materials into molds, and for various other uses. i

The invention herein set forth is susceptible of various modifications and adaptations without departing from the scope thereof as hereafter claimed.

The invention is hereby claimed as follows:

1. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel, means for advancing and retracting said screw and said flywheel, and means for connecting sa d flywheel to said. screw to cause it and said screw to rotate in unison during the advance thereof and to enable said flywheel to be retracted without rotating.

2. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel, means for advancing and retracting said screw and said flywheel, and a clutch for connecting said flywheel to said screw to cause it and said screw to rotate in unison during the advance thereof and to enable said flywheel to be retracted without rotating.

3. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel, hydraulic means for advancing and retracting said screw and said flywheel, and means for connecting said flywheel to said screwto cause it and said screw to rotate in unison during the advance thereof and to enable said flywheel to be retracted without rotating.

4. A percussion press, comprising a frame having athreaded bore, a power screw threaded through said bore, a flywheel, a hydraulic motor said screw and said flywheel, and a jaw clutch for connecting said flywheel to said screw to cause it and said screw to rotate in unison during the advance thereof and to enable said flywheel to be retracted without rotat-ing.

5. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel, means for applying power axially to said screw to advance and retract the same and thereby cause rotation thereof, and means for connecting said flywheel to said screw to cause it to rotate in unison therewith during theradvance thereof and to enable said flywheel to be retracted without rotating.

6. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel,, means for applying power axially to said screw to advance and retract the same and thereby cause rotation thereof, a clutch for connecting said flywheel to said screw to cause it to rotate in unison therewith during the advance thereof and to enable said flywheel to be retracted without rotating.

7. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel, a hy' draulic motor for'applying power to said screw to advance and retract the same and thereby cause rotation thereof, means for connecting said flywheel to said screw to cause it to rotate in unison therewith during the advance thereof and to enable said flywheel to be retracted without rotating, and means for varying the stroke of said press.

8. A percussion press, comprising a frame' having a threaded bore, a power screw threaded through said bore, a flywheel, a hydraulic motor for applying power to said screw to cause rotation thereof, means for connecting said flywheel to said screw to cause it to rotate in unison therewith during the advance thereof, and means for reducing the displacement of said motor during the advance of said screw to thereby accelerate the speed of said flywheel.

having a threaded bore, a power screw threaded through said bore, a flywheel, a hydraulic motor for applying power to said screw to advance and retract the same to cause rotation thereof, means for connecting said flywheel to said screw to cause it to rotate in unison therewith, means for supplying a driving liquid to said motor to operate the same, and means for progressively decreasing the displacement of said motor during the advance of said screw to thereby progressively increase the speed of said flywheel.

10. A percussion press, comprising a frame or advancing and retracting having a threaded bore, a power screw 9. A percussion press, comprising a frame Isa threaded through said bore, a flywheel, a hydraulic motor for applying power to said screw to advance and retract the same and to cause rotation thereof, a clutch for connecting said flywheel to said screw to cause 1t to rotate in unison therewith, means for supplying a driving liquid to said motor to operate the same, means for progressively decreasing the displacement of said motor during the advance of said screw to thereby progressively increase the speed of said flywheel, and means for varying the stroke of said press.

11. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel, a

' hydraulic motor having a piston for applying power axially to said screw to advance and retract the same and thereby cause rotation thereof, means for connecting said flywheel to said screw to cause it to rotate in unison therewith, means for supplylng a driving liquid to said motor to operate the same,and means for decreasing the eifectlve area of said piston during the advance of sa d screw to thereby increase the speed of said flywheel.

12. A percussion press, comprlsing a frame having a threaded bore, a power screw threaded through said bore, a flywheel, a hydraulic motor having a piston for applying power axially to said screw to advance and retract the same and thereby cause rotation thereof, means for connecting sa1d flywheel to said screw to cause it to rotate 1n unlson therewith, means for supplying a drivmg liquid to said motor to operate the same, and means for bypassing liquid from the exhaust end of said motor to the pressure end thereof after said screw .has advanced a predetermined distance to thereby increase the speed I of said flywheel.

13. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel arranged upon sald screw, a hydrauhc motor having a piston for applymg power axlally to said screw to advance and retract the same and thereby cause rotation thereof, means for connecting said flywheel to said screw to cause it to rotate in unison therew1th, means for supplying a driving liquid to said motor to operate the same, means for bypassing liquid from the exhaust end of said mptor to the pressure end thereof after said screw has advanced a predetermined distance to thereby increase the speed of said flywheel, and means for varying said predetermined distance.

14. A percussion press, compr1s1ng a frame having a threaded bore,'a power screw threaded through said bore, a flywheel, a hydraulic motor for applying power to said screw to advance and retract the same and to cause rotation thereof, means for supplying driving liquid to said motor to operate the same,

means'for connecting said flywheel to said screw to cause it to rotate in unison therewith and to enable said. flywheel to be retracted without rotating, and means for decreasing the displacement of said motor during the advance of said screw to thereby increase the speed of said flywheel. 5

15. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel, a hy' draulic motor for applying power to said screw to advance and retract the same and to cause rotation thereof, means for supplying driving liquid to said motor to operate the same, a jaw clutch for connecting said flywheel to said screw to cause it to rotate in unison therewith, and means for progressively decreasing the displacement of said motor during the advance of said screw to thereby progressively accelerate the speed of said flywheel. 5

16. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel, a hydraulic motor for applying power to said screw to advance and retract the same and to cause rotation thereof, a variable delivery constant pressure pump for supplying driving liquid to said motor to operate the same, a jaw clutch for connecting said flywheel to said screw to cause it to rotate in unison therewith and to enable said flywheel to be retracted without rotating, and means for decreasing the displacement of said motor during the advance of said screw tothereby increase the speed of said flywheel.

17, A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a flywheel, a hydraulic motor having a piston for applying power axially to said screw to advance and retract the same and thereby cause rotation thereof, means for supplying driving liquid to said motor to operate the same, a jaw clutch for connecting said flywheel to said screw to cause it to rotate in unison therewith and to enable said flywheel to be retracted without rotating, and means for bypassing liquid from the exhaust end of said motor to the pressure end thereof after said screw has been advanced a predetermined distance to thereby decrease the effective area of said piston and increase the speed of said flywheel.

18. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a hydraulic motor having its cylinder carried by said frame, a tubular piston fitted in said cylinder and having a relatively short stroke therein, a solid piston fitted in said tubular-piston and having a longer stroke, a piston rod carried by said solid piston for applying power .frame having a threaded bore, a power-screw threaded through said bore, a hydraulic motor having its cylinder carried by said frame, a composite piston fitted in said cylinder and comprising interfitted piston sections having strokes of diflerent lengths, a piston rod carried by one of said piston sections for applying power axially to said screw to advance and retract the same and thereby cause rotat'ion thereof, a flywheel arranged upon said screw, means for connecting said flywheel to said screw to cause it to rotate in unison therewith during the advance thereof and to enable said flywheel to be retracted without rotating, means for supplying liquid to said motor to cause said piston rod to advance a predetermined distance under the pressure exerted by said liquid upon the combined areas of said piston sections, and means for progressively stopping the strokes of said piston sections to thereby progressively accelerate the speed of said flywheel.

20. A percussion press, comprising a frame having a threaded bore, a power screw threaded through said bore, a ram carried by said screw upon the lower end thereof and guided by said frame, a hydraulic motor carried by said frame and having a piston for applying-power axially to said screw to advance and retract the same and thereby cause rotation thereof, a flywheel arranged upon the upper end of said screw, a clutch for connecting said flywheel to said screw to cause it to rotate during the advance thereof and to enable said flywheel to be retracted without rotating, a variable delivery constant pressure pump for supplying liquid to said motor, a control valve for controlling the delivery of said liquid, a bypass valve for bypassing liquid from one end of said motor to the other end thereof, hydraulic means for operating each of said valves, a drain valve for controlling the discharge of liquid from said hydraulic means, manual means for operating said control valve to deliver liquid to said motor to advance said piston, means operated by the advance of said piston for operating said bypass valve to bypass liquid from the rod end of said motor to the head end thereof, means for operating said drain valve at the end of the advance of said piston to cause said hydraulic means to operate said bypass and control valves and therethe press.

WALTER FERRIS.

Nil

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