US2758837A

US2758837A - Hydraulically powered rack and pinion feeding mechanism

Info

Publication number: US2758837A
Application number: US343206A
Authority: US
Inventors: Frederick M Littell; Chester M Wiig
Original assignee: Littell Machine Co F J
Current assignee: FJ Littell Machine Co
Priority date: 1953-03-18
Filing date: 1953-03-18
Publication date: 1956-08-14
Anticipated expiration: 1973-08-14

Description

Aug. 14, 1956 F. M. LITTELL Er/u. 2,758,337

HYDRAULICALLY POWERED RACK AND PINION FEEDING-MECHANISM v Filed March 18, 1953 f 6 Sheets-Sheet 1 Jizvevgiars,

Aug. 14, 1956 F. M. LITTELL EI'AL HYDRAULICALLY POWERED RACK AND PINION FEEDING MECHANISM 6 Sheeis-Sheet 2 Filed March 18, 1953 I E I Aug. 14, 1956 F. M. LITTELL EFAL 2,758,837

HYDRAULICALLY POWERED RACK AND PINION FEEDING MECHANISM- Filed March 18, 1953 6'Sheets-Sheet 3 FRICTIOAML A/VD WJAK OAD IN 76/9615 TOTAL TORQUE 0 MA N El /4 T OF TORQUE 0N MAI/ 57 1 7 ACTUAL DRAG RAKE FRIC TIONIL A/VD work L040 L555 OVEAIVIl/L lms [/rggr AT FEED ROLL SHAFT Aug. 14, 1956 F. M. LITTELL ETAL HYDRAULICALLY POWERED RACK AND PINION FEEDING MECHANISM Filed March 18, 1953 6 Sheets-Sheet 4 6& fehf.

Aug. 14, 1956 F. M. LlTTELL E.TAL, 2,758,837

HYDRAULICALLY POWERED RACK AND PINION FEEDING MECHANISM Filed March 18, 1953 6 Sheets-Sheet 5 E2 142 fl Z" 7 J43 H7 J53 J35 I I w" W HIGH Pksssums smws H Um Mega/ LOW pmsssmm- FLUID Aug .14, 1956 F. M. LITTELL EI'AL 3 HYDRAULICALLY POWERED RACK AND PINION FEEDING MECHANISM Filed March 18; 1953 e sneaks-sheet e United States Patent HYDRAULTCALLY POWERED RACK AND PINION FEEDING MECHANISM Frederick M. Littell and Chester M. Wiig, Chicago, 11]., assignors to F. J. Littell Machine Company, (Jhicago, Ill., a corporation of Illinois Application March 18, 1953, Serial No. 343,206v

4 'Claims. (Cl. 271-2.4)

The invention relates to material feeding mechanism for feeding metal or other material in continuous strip form to punch presses and the like and has reference in particular to simple and efficient mechanism for controlling the braking pressures applied to the feed rolls whereby to insure proper functioning of the feed roll drive mechanism.

Metal working machines such as punch presses are operated in conjunction with mechanism whereby metal strip material is conditioned and fed to the reciprocating plunger of the press for blanking, punching or similar operations, and which requires precision feeding at high speeds in order to obtain a substantial output for the mechanism. The several operating units which go to make up the conditioning and feeding machine are usually mounted in longitudinal alignment upon a suitable base and actuated from a main drive shaft through a ratchet or over-running type of drive means for positively bringing the feed rolls up to desired speed and which permits the rolls to over-run the drive under certain conditions. It is necessary to apply friction braking pressure to such an over-running type of drive so that the inertia of the rotating parts will not cause the feed rolls to over-ride, which over-riding, if permitted, would of course destroy the accuracy of the measured feed lengths.

Therefore, an object of the present invention resides in the provision of an hydraulically propelled rack and pinion type drive for driving the feed rolls of a feeding and straightening machine and which will incorporate friction brake means constructed and arranged to open and close by the rise and fall in the pressure of the hydraulic fluid.

The present mechanism provides hydraulic propelling means for continuously driving the main operating shaft of the mechanism, which, in turn is operatively con nected to the feed rolls by a reciprocating rack driving an over-running clutch, the rack having an operating stroke and a non-operating stroke for each revolution of the main shaft. Thus, the intermittent driving of the feed rolls results in the feeding of measured lengths of strip material and it will be understood that the torque on the main shaft will be variable whereby to cause pressure variations in the hydraulic fluid in direct proportion thereto. The invention resides in the provision of a small pressure line from the hydraulic pump to the hydraulic brake cylinder and during operation of the mechanism the brake is caused to open during high torque on the main shaft as a result of the high pressure in the line, and, conversely, the brake is permitted to close during low torque on the main shaft because of the low pressure in the line.

Therefore another object of the invention is to provide automatic means for controlling the braking pressures applied to intermittently driven feed rolls to prevent overrun, the said braking pressures being inversely proportional to the pulling torque on the main operating shaft and therefore being variable, and wherein the application of said braking pressures is accomplished progressively and efliciently and without any shock to the mechanism.

Another object of the invention is to provide a simple hydraulic circuit including an hydraulic pump and motor for continuously driving the main operating shaft of the mechanism and wherein flow of the hydraulic fluid in the circuit is controlled by relief valves and by a conventional control valve which may be solenoid actuated.

Another object of the invention resides in the provision of improved mechanism for driving the feed rolls of a feeding and straightening machine, which mechanism will be hydraulically propelled, wherein the application of the friction braking pressures will be automatic, being inversely proportional to the torque on the main operating shaft, and wherein the mechanism can be set for double or triple cyling to double or triple the feed lengths measured by the feed rolls.

With these and various other objects in view, the invention may consist of certain novel features of construction and operation as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings which illustrate an embodiment of the invention, and wherein like reference characters are used to designate like parts- Figure l is a front elevational view of a feeding and straightening machine embodying the hydraulically powered rack and pinion feeding mechanism of the invention and which additionally includes an hydraulic releasing brake;

Figure 2 is a side elevational view of the feeding and straightening machine of Figure 1, the hydraulic releasing brake being clearly illustrated in association with the lower feed roll;

Figure 3'is a horizontal sectional view taken substantially along line 3-3 of Figure 2;

Figure 4 is a longitudinal sectional view taken substantially along line 4--4 of Figure 1 showing the lower feed roll shaft, and the friction brake, the pinion, and the over-running clutch in association therewith;

Figure 5 is a sectional view taken substantially along line 55 of Figure 4 showing the rack and pinion drive;

Figure 6 is a sectional view taken substantially along line 6-6 of Figure 4, illustrating the construction of the over-running clutch;

Figure 7 is a schematic view illustrating the hydraulic system of the invention and showing the control valve in operative position, and the hydraulic releasing brake under pressure;

Figure 8 is a schematic view similar to Figure 7 but showing the hydraulic system of the invention with the control valve in non-operative position;

Figures 9 to 13 inclusive are schematic views illustrating the various functions of the hydraulic releasing brake; and

Figure 14 is a view illustrating graphically by means of curves the several factors controlling the design and operation of the hydraulic releasing brake and their relation to each other.

Referringin particular to Figures 1 and 2 of the drawings, the invention is illustrated as applied to a straightening and feeding machine, adapted to receive metal strip material, and after straightening and otherwise conditioning the strip material the same is fed by a pair of feed rolls to a punch press oijsimilar machine for fabricating the material of the strip by means of pressing, punching or blanking operations. The several parts going to make up the straightening and feeding machine are supported by a metal cabinet or housing structure such as indicated by'numeral 10 and which includes a top wall 11, front and rear walls 12 and 13,

side walls

14 and 15, and a base member such as 16'. Intermediate partitions such as 17 and 18 are located within the cabinet to provide supporting structure for an electric motor and for driving elements, all to be presently described in detail. The partition 17 in combination with the vertical partition 20 forms an oil reservoir or sump 21 within the cabinet for containing a supply of oil for the hydraulic circuit including a fluid pump and motor by means of which the main operating shaft of the mechanism is continuously rotated.

The straightening and feeding unit indicated in its entirety by numeral 24 is supported on the top wall 11 of the cabinet. The straightening unit consists of upper feed rolls such as 25 and lower feed rolls such as 26, the latter being geared to rotate in unison by the gear wheels 27 and by the idler pinions 28. The upper rolls 25 of the straightening unit are each located centrally above a pair of lower rolls and in order to accomplish a straightening function the upper rolls are adjustably mounted, being journalled by the blocks 30 adapted to be moved vertically by means of threaded studs, not shown, by rotation of the hand wheel 31. The metal strip material in passing through the straightening unit is bent in a direction opposite the curvature assumed by the metal strip when in coil form. From the straightening unit the metal strip material passes through forward feeding rolls located at the forward end of the machine. The upper feeding roll 32 is suitably mounted in the side frames 33 and 34, the right hand end of the journalling shaft for feed roll 32 extending through side frame 34 and being provided with the driving gear 35. The lower feed roll 36 is likewise journalled for rotation by the side frames 33 and 34 and as regards this feed roll, the supporting shaft 37 thereof, see Figure 4, extends through both side frames to project some distance beyond. At the right hand end, Figure 1, the extending end of shaft 37 is provided with the gear 38, the same having meshing relation with gear whereby rotation of the lower feed roll will effect rotation of the upper feed roll. The left hand extension of shaft 37 is provided with the gear 40', the same being located immediately adjacent side frame 33. An idler pinion 28, Figure 2, as previously described in connection with the straightening unit, has meshing relation with gear 40 and thus all of the straightening rolls are driven from shaft 37 It will be understood that the upper feed roll 32 is actually journalled by blocks 39, in a manner similar to the upper straightening rolls, and the blocks are mounted by the side frames 33 and 34 for vertical movement toward and from the lower feed roll 36. Coil springs 46, located within cover 41, are provided for tensioning the upper feed roll by maintaining resilient pressure on the bearing blocks 29 whereby to force the upper feed roll into contact with the lower feed roll, all as will be clearly understood in connection With conventional straightening and feeding machines. However, it is necessary at times to initially insert the metal strip indicated by the broken line 22, Figure 2, between the feed rolls, for which purpose the upper feeding roll 32 is provided with a hand lever 43, with cams 44, adapted to be rotated upon actuation of said lever, and with lifter levers such as 45. When the lifter levers are cammed in a downward direction the bearing blocks journalling the upper feed roll 32 are elevated whereby to separate the upper feed roll from the lower feed roll. After the strip material has been threaded or inserted between the feeding rolls the lifter levers are released, allowing the upper feed roll to resiliently bear against the material, which is accordingly pinched or gripped by the feeding rolls.

The feed rolls of the straightening and feeding unit are rotated intermittently by shaft 37, the extent of rotation being adjustable in order that the lengths of strip material fed by the machine may be varied. In accordance with the invention shaft 37 is driven by a rack and pinion drive through an over-running clutch whereby the rack has an operative stroke when reciprocated in one direction and has a non-operative stroke when reciprocated in the reverse direction. Because of this intermittent driving of the lower feed roll shaft 37 it is necessary to frictionally brake the shaft at certain times during each cycle of operations in order to prevent over-run of the feeding rolls which, if permitted to take place, would of course destroy the accuracy of the measured feed lengths. The rack and pinion structure, the over-running clutch, and the friction braking means are disclosed in detail in Figures 4, 5 and 6. The reciprocating rack identified by numeral 47 is adapted to ride within the rack and pinion housing 43, the same including a cover plate 50 and a rear plate 51. The body portion of the rack and pinion housing is supported on the trunnions 54 of the pinion 52, the pinion being journalled for free rotation on the left hand extending portion of said shaft 37, there being interposed between the shaft and said pinion suitable bearings such as 53. The trunnions 54 of the pinion 52 are integral therewith and said trunnions extend on the respective sides of the pinion. The right hand trunnion is extended by having formed integral therewith the cylindrical casing 55' of the over-running clutch, indicated in its entirely by numeral 56. It will be understood, therefore, that the pinion 52 constitutes an integral unit with the cylindrical casing 55 of the over-running clutch, indicated in its entirety by numeral 56. Said over-running clutch additionally includes the inside element or hub member 57, the same being keyed as at 53 to shaft 37 so that any rotation imparted to hub member 57 will be transmitted to the feed roll drive shaft 37. The hub member 57 is provided with off-center gripping faces 60, which faces are reinforced by the hardened steel inserts 61 adapted to support the gripping rolls 62. The rollers are located between the gripping faces, provided by the steel inserts 6i, and the inside cylindrical gripping surface 63 of the casing 55, and by means of the pins 64, which are backed by the coil springs 65, a one-way clutch is provided whereby only one reciprocating stroke of the rack 47 will be transmitted to the shaft 37. The position of the rack 47 on the right hand side of the pinion 52, Figure 5, and the particular orientation of the clutch hub 57 is such that movement of the rack 47 in a downward direction constitutes an operating stroke of the rack, producing rotation of the shaft 37 and rotation of the feeding and straightening rolls for a feeding operation. Conversely, reciprocating movement of rack 47 in an upward direction constitutes a non-operative stroke with the result that no rotation is imparted through the one-way clutch to shaft 37. The plate 66 is releasably secured to the clutch casing 55 and said plate completes the clutch structure since it functions to retain the gripping rolls 62 in place, preventing lateral displacement thereof.

The left end of shaft 37, Figures 1 and 4, projecting beyond the rack and pinion housing 48 extends through a brake supporting bracket 63 suitably fixed to side wall 14 of the cabinet 10. The brake supporting bracket 68 is employed as a journalling member for this left projecting end of shaft 37, the said bracket accommodating the roller bearing 69 which journals this projecting end of shaft 37. Immediately beyond the roller bearing 69 the projecting end of shaft 37 is provided with the brake drum 70, the drum being keyed as at 71 to shaft 37, and being retained in place on the shaft by the threaded nut 72. A feature of the invention resides in the provision of a friction brake having operative association with the brake drum 70 for snubbing or braking the feed roller drive shaft whereby to prevent over-run of the feed rolls which might otherwise take place, particularly at high speeds. A jaw-type brake is provided, the same being indicated in its entirety by numeral 73 and including opposed brake arms 74 and "i5 pivotally supported at their top end by means of pin 76 having a fixed relation with the brake supporting bracket 68, and said brake arms at their opposite ends being operatively connected by two instrumentalities, one comprising resilient brake applying means and the other comprising the hydraulic brake releasing means. The resilient brake applying means consists of a connecting bolt 77 fixed at 78 to brake arm 75 and passing through an opening in brake arm 74 to extend beyond sail arm for receiving the coil spring 80. Said coil spring is held to the connecting rod 77 by the securing nut 81, and thus the spring is confined between the nut at its left hand end and the brake arm 74 at its right hand end. Accordingly, the action of the coil spring 80 is such as to close the brake arms, or, in other words, to cause said brake arms to move toward each other, whereby the intermediate brake portion thereof, having contact with the brake drum "/0, is caused to frictionally engage the brake drum to thus apply braking or snubbing action to the feed roll drive shaft 37.

The brake releasing means is also operatively associated with the

brake arms

74 and 75, said means being hydraulically actuated and functioning to open or release the brake arms to thus free the brake drum so that the feed roll drive shaft 37 is able to rotate freely. The hydraulic cylinder 82 is suitably fixed to brake arm 74 and said cylinder is supplied with fluid under pressure by means of supply pipe 83. The piston 84 within cylinder 82 is fixed to the threaded connecting rod 85 which extends through the lower end of brake arm 74 and is threaded to brake arm 75. The right hand projecting end of rod 85 retains the locking nut 86 by which it is possible to lock rod 85 in desired threaded position as regards arm 75. When the locking nut 86 is released the rod 85 can be rotated by applying a wrench or similar tool to the end nut 87, and accordingly, it is possible to vary the releasing action of the hydraulic cylinder when hydraulic fluid under pressure is supplied thereto. In accordance with the invention the pressure of the hydraulic fluid supplied to cylinder 82 will be relatively high to effect an opening action of the

brake arms

74 and 75 when the torque on the main shaft is high, and, conversely, the pressure of the hydraulic fluid supplied to cylinder 82 will be low, thus permitting

brake arms

74 and 75 to close, when the torque on the main shaft is low. In this connection, it will be understood that the torque on the main shaft is variable because the rack has a driving stroke during downward movement to cause rotation of the feed rolls, and said rack has a nonoperative upward stroke during which the feed rolls remain at rest, when only the pinion 52 and clutch casing 55 are rotated. The main operating shaft for reciprocating the rack and the hydraulic circuit for continuously driving the main operating shaft will now be described.

Referring to Figure 3, the hydraulic circuit drives an auxiliary shaft 90 located within cabinet and suitably journalled at respective ends by bearings 91 and 92. The bearing unit 91 is suitably supported by journalling bracket 93, fixed to front wall 12 of cabinet 10. The journalling bracket 93 is closed by cap 94 which protects this end of shaft 90, the said end receiving the securing nut 95 which retains the bearings 91 in place. At the opposite end of shaft 90 the bearing 92 is supported by journalling bracket 96 which is suitably mounted by the vertical partition 20 within cabinet 10. This right hand end of auxiliary shaft 90 extends through its journalling bracket 96 to connect with the coupling 97 which operatively joins said auxiliary shaft to its hydraulic drive means, which will be presently described in detail.

The auxiliary shaft 90 is provided with the worm pinion 98 which has meshing relation with Worm gear 100, Figure 1. The worm gear is suitably fixed to the main operating shaft 101 and which is journalled at respective ends by means of roller bearings 102 and 103. Bearing 102 is suitably mounted in the vertical partition 104, said partition providing the bearing housing 105 within which bearing 102 is mounted. The nut 106 is threaded to this right hand end of the main operating shaft 101 and the structure is suitably enclosed by means of cap 107. The main operating shaft at its left hand end extends through and beyond bearing 103 which is suitably supported by the plate structure 108 provided for the purpose and which is secured to, so as to form a part of side wall 14. The main operating shaft 101 of the mechanism is provided with the face plate or disc 110 having the radial groove 111 formed in its outer surface and within which is mounted the threaded stud 112. It will be seen from Figure 1 that the threaded stud 112 is held to the disc 110 by means of rollers 113 which locate the threaded stud within groove 111 in addition to mounting the same for rotation. The stud may be rotated by applying a suitable tool to the square end 114 thereof, and depending on the direction of rotation of said stud, it will be seen that the block 115 will be adjusted along groove 111 either radially inward as a result of rotation of the stud in one direction, or radially outward as a result of rotation of the stud in an opposite direction. Said block 115 has the stud shaft 116 integral therewith and the lower end of rack 47 is mounted on said stud shaft through the instrumentality of the ball bearing race 117. The securing nut 118 and plate 119 function to retain this end of the rack on the stud shaft 116 while permitting rotation of the main operating shaft 101 whereby reciprocating movement is accordingly imparted to said rack. Since the block 115 is adjustable within groove 111 it is possible to vary the magnitude of the reciprocating stroke of rack 47. By rotating threaded nut 112 in a direction to locate block 115 radially inward toward the center of the main operating shaft the stroke of the rack is correspondingly reduced, and when the stud is rotated to move the block 115 radially outward toward the periphery of the disc 110 the stroke of the rack is correspondingly increased.

The rack 47 is reciprocated by an electric motor 120, Figure 3, which operates through an hydraulic circuit to drive the worm 98, and thus gear 100 and the main operating shaft 101. The electric motor 120, Figures 7 and 8, drives the hydraulic pump 121 which is connected through piping 122 with the relief valve designated in its entirety by numeral 123. From said relief valve the piping 12.4 leads to the fluid motor 125 and it will be seen from Figure 3 that shaft 126 of said fluid motor is suitably joined to coupling 97, which functions to couple the fluid motor with the auxiliary shaft 90. The piping 127 leads from the fluid motor 125 and connects the same to a second relief valve generally designated by numeral 128. The fluid pump 121 receives its supply of oil or hydraulic fluid through tubing 130 extending into the sump or reservoir 21 and having its inlet end provided with the filter 131. The fiuid from relief valve 123 is returned to the sump under certain conditions for which purpose said relief valve is provided with the drain pipe 132 which extends through partition wall 17 and terminates within the sump. In a similar manner the relief valve 128 is provided with a drain pipe 133 which also extends through partition wall 17 and terminates within the sump. The fluid motor 125 is provided with a bleed line 134 which is normally closed but which may be opened to also drain the motor to the sump. The tubing 124 is tapped as at 135 to provide a connection therewith for the supply line 83 which leads to the brake cylinder 82, Figure 2. A bleed line 136 may be provided for connecting the rear of the cylinder beyond the piston 84 with the sump.

The hydraulic circuit is controlled by means of a control valve or pilot valve indicated in its entirety by numeral 138 and which includes the solenoid 140 operatively connected through stem 141 with the spool valve 142. The coil spring 143 resiliently urges the spool valve into an idling or inoperative position. Relief valve 123 is connected to the control valve by tubing 144 and similar tubing 145 connects the control valve and the relief valve 128. A drain pipe 146 leads from the control valve to the sump and the passage 147 formed in the valve connects the tubing 144 with said drain pipe. Figure 7 illustrates the flow of oil in the hydraulic circuit when the control valve is energized and the feed rolls are accelerating so that torque on the main shaft is a maximum. Energization of the control valve moves the spool valve to the left against the pressure of spring 143 and the passage for tubing 144 is closed, thereby preventing flow of oil from tubing 144 through 147 to the drain pipe 146. As a result the pressures above and below valve 148 of the relief valve 123 are balanced and said valve is caused to move against its valve seat 150, thus closing off the drain 132. Valve 148 is provided with opening 151 leading to the chamber above the valve and which chamber connects with tubing 144 through pasasge 152. The valve 148 closes when flow through tubing 144 is stopped because the pressures above and below valve 148 are equalized. Accordingly, the oil instead of returning to the sump through drain 132 is caused to flow through tubing 124 to fluid motor 125, causing rotation of the main operating shaft 101, reciprocation of rack 47, and operation of the feed rolls. The oil discharged by fluid motor 125 is delivered by tubing 145 to the relief valve 128. Thus it will be understood that tubing 145 communicates through passage 153 with the drain 146 of said control valve, and oil may flow through tubing 145 to the sump. As a result the valve 154 of the relief valve 128 is unbalanced so that the valve is lifted ofi of its valve seat 155. The drain 133 is therefore opened and the oil will be discharged through the drain to the sump.

As long as the solenoid 140 remains energized the hydraulic circuit will operate to drive the fluid motor 125. For normal operation of the straightening and feeding machine the solenoid is energized for each revolution of the main shaft and is then tripped at the end of the cycle. Thus the rack will have an operative stroke to feed the desired length of strip material and will then have a non-operative stroke, completing one cycle of operation. However, it is entirely possible to control the electric impulses delivered to solenoid 140 so that double cycling or even triple cycling of the feeding and straightening machine may result.

Upon de-energization of solenoid 140 the coil spring 143 will function to return the spool valve 142 to its initial position, in which position tubing 144 is open through passage 147 to drain 146, whereas tubing 145 is now closed by the spool valve. Since oil is now able to flow through tubing 144, the valve 148 of the relief valve 123 will be unbalanced and the valve will lift from its valve seat to open drain 132. With said drain open the oil pumped by 121 is delivered back to the sump and the fluid motor 125 is not operative so that the main operating shaft of the mechanism thus remains idle.

Referring again to Figure 7, which schematically illustrates operating pressures in the hydraulic system, it will be understood that the fluid pressure will vary from a maximum to a minimum value during each cycle of operation. This is due to the fact that the pressures developed are dependent upon the load and the relative position of the torque arm, which forms the mechanical linkage to the feeding rolls. Figure 7 illustrates the maximum pressures developed during an operative stroke of the reciprocating rack and more particularly during the accelerating portion of such operating stroke when the pulling torque is a maximum. It will be understood that the feeding rolls must do work in feeding the material at an accelerating rate and thus the fluid motor 125, which drives the rolls, must necessarily be supplied with an hydraulic fluid at a high pressure. The high pressure thus developed in the hydraulic circuit leading to the fluid pump is automatically transmitted through supply line 33 to the brake cylinder 82. The action of the hydraulic pressure against piston 84 is to move the piston to the right, effecting a releasing action of the

brake arms

74 and 75. Thus during this period of high torque on the main operating shaft the friction brake is automatically released. For a better understanding of this feature of the invention, reference is made to Figures 9 to 13 inclusive. In Figure 9 the position of the parts is such that the hydraulic pressure in the brake cylinder is not high enough to release the friction brake. However, the mechanical leverage is considerable and the hydraulic pressure can be expected to rise at a rapid rate. This has taken place by the time the parts have moved to the position as shown in Figure 10. The rotating parts are accelerating for Figures 9, 10 and 11 and the frictional force to be overcome is relatively high as is also the inertia load.

By the time rotating parts have moved to the position as shown in Figure 12, deceleration of the same has already taken place. In fact, deceleration of the rotating parts takes place approximately five to eight degrees before the crank arm and rack reach the position as shown in Figure 12. With deceleration no further work is required of the feeding rolls but, on the contrary, braking effort is required to slow down the feed rolls and bring the rotating parts to rest. The inertia load has changed from high to overhauling and thus the torque on the main operating shaft has likewise been reduced to overhauling so that the pressures within the hydraulic system are practically zero. As a result the brake releasing means is rendered inoperative and the resilient spring has again applied the brakes to brake and decelerate the feed roll drive shaft. With the position of the parts as shown in Figure 13 the operative stroke of the rack is substantially completed. Feeding, however, will continue until bottom dead center is reached, at which point it is de sired to bring the feed rolls to a stop and the greater the accuracy in controlling this stopping point of the feed rolls, the greater the accuracy in the feeding of measured lengths of strip material. The resilient pressure for braking or snubbing the brake drum can be adjusted to suit various conditions by tightening up or releasing nut 81 which will change the pressure applied by spring 80. As far as the brake releasing means is concerned, the operating pressures in the hydraulic circuit can be adjusted by rotation of hand Wheel 156 provided by the relief valve 123, and by rotation of hand wheel 157 provided by relief valve 128.

The invention is not to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawings as various other forms of the device will of course be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

What is claimed is:

1. In a machine of the class described, in combination with feeding rolls for feeding strip material, a feed roll drive shaft, a one-way clutch on the feed roll drive shaft, and a reciprocating rack for rotating the feed roll drive shaft through the said one-way clutch, whereby said rack has an operative stroke and a return inoperative stroke to intermittently rotate the feed roll drive shaft for feeding measured lengths of strip material, and whereby each operative stroke of the rack includes an initial accelerating portion during which the torque is a maximum for rotating the feed rolls and for accelcrating them, and also includes a terminating decelerating portion of low torque since the feed rolls have a tendency to overrun due to the one-way clutch, hydraulic power means for reciprocating the rack, normally operative brake means for said feed roll drive shaft, brake releasing means including a cylinder and a piston connected to said brake means, an hydraulic circuit for said hydraulic power means for supplying a high pressure fluid to the power means during the accelerating high torque portion of the operative stroke of the rack, the fluid pressure in the hydraulic circuit being reduced to Zero during the low torque decelerating portion of the operative stroke of the rack, and connections between the cylinder and said hydraulic circuit for transmitting the variable fluid pressures occurring in the hydraulic circuit to the cylinder, whereby to effect release of the brake means during the said high torque accelerating portion of the operative stroke of the rack.

2. In a machine of the class described, in combination with feeding rolls for feeding strip material, a feed roll drive shaft, a main operating shaft having a crank arm connected thereto, a one-way clutch on the feed roll drive shaft, and a rack connecting the crank arm with the feed roll drive shaft through the one-way clutch, whereby each revolution of the operating shaft produces an operative stroke and an inoperative stroke of the rack to intermittently rotate the feed roll drive shaft for feeding measured lengths of strip material, and whereby each operative stroke of the rack includes an initial accelerating portion during which the torque is a maximum for rotating the feed rolls and for accelerating them, and also includes a terminating decelerating portion of low torque since the feed rolls have a tendency to overrun due to the one-way clutch, hydraulic power means for rotating the main operating shaft, normally operative brake means for said feed roll drive shaft, brake releasing means including a cylinder and a piston connected to said brake means, an hydraulic circuit for said hydraulic power means for supplying a high pressure fluid to the power means during the accelerating high torque portion of the operative stroke of the rack, the fluid pressure in the hydraulic circuit being reduced to zero during the decelerating low torque portion of the operative stroke of the rack, and connections between the cylinder and said hydraulic circuit for transmitting the variable fluid pressures occurring in the hydraulic circuit to the cylinder, whereby the brake releasing means is actuated to release the brake means when the hydraulic pressures exceed a predetermined maximum, and whereby said brake means is permitted to normally brake the feed rolls when said hydraulic pressures are lower than the predetermined maximum.

3. In a machine of the class described, in combination with feeding rolls for feeding strip material, a feed roll drive shaft, a main operating shaft having a crank arm connected thereto, a one-way clutch on the feed roll drive shaft, and a rack connecting the crank arm with the feed roll drive shaft through the one-way clutch,

whereby each revolution of the operating shaft produces an operative stroke and an inoperative stroke of the rack to intermittently rotate the feed roll drive shaft for feeding measured lengths of strip material, and whereby each operative stroke of the rack includes an initial accelerating portion during which the torque is a maximum for rotating the feed rolls and for accelerating them, and also includes a terminating decelerating portion of low torque since the feed rolls have a tendency to overrun due to the one-way clutch, hydraulic power means including a fluid motor for rotating the main operating shaft, resilient brake means for the feed roll drive shaft normally operative to apply a predetermined pressure sufficient to prevent overrun of the feed rolls following the decelerating portion of the operative stroke of the rack, brake releasing means including a cylinder and a piston connected to said brake means, an hydraulic circuit for said hydraulic power means including a fluid pump for supplying a high pressure fluid to the power means during the accelerating portion of the operative stroke of the rack, the fluid pressure in the hydraulic circuit being reduced to zero during the decelerating portion of the operative stroke of the rack, and conduit means connecting the cylinder with the hydraulic circuit whereby the variable hydraulic pressures developed in the circuit are applied to the piston of said cylinder, and whereby the brake releasing means is actuated to release the brake means only when high pressures exist in the hydraulic circuit, the said brake means being permitted to normally brake the feed roll drive shaft when low pressures exist in the hydraulic circuit.

4. A machine of the class described as defined by claim 3, additionally including threaded means which are manually operable for adjusting the length of the crank arm.

References Cited in the file of this patent UNITED STATES PATENTS 1,782,362 McArthur Nov. 18, 1930 1,871,272 Jongedyk Aug. 9, 1932 2,315,446 Miller et a1 Mar. 30, 1943 2,647,455 Adams Aug. 24, 1953