US3817067A - Stock supply system - Google Patents

Abstract

A stock supply system, especially for supplying strip stock from a supply thereof to a feed device pertaining to a machine in which the supply system includes a straightening roller stand driven by a variable speed drive and with an arrangement provided for maintaining a loop in the stock being supplied between the straightening roller stand and the feed device. The feed device operates intermittently to supply the stock to a machine and the machine supplies a signal on each cycle that tends to increase the speed of the variable speed drive. A feedback signal tends to reduce the speed of the variable speed drive thereby tending to maintain the aforementioned stock loop at about a fixed size. When the loop exceeds a certain length, the speed of the drive is reduced, and if the loop shortens beyond a predetermined amount, the machine being fed and the feed device and the roller stand come to a halt.

Description

Voorehes et a1 1 1 June 18, 1974 STOCK SUPPLY SYSTEM [75] Inventors: John E. Voorehes, Sidney; Robert M. Carabbio, St. Marys, both of Primary l;'.ramirwrMilton Mchr Attorney, Agent, or Firm-A1bert L. Jeffers; Roger M. Rickert ABSTRACT Ohio [57] [73 Assignee: The Minster Machine Company, A stock supply system, especially for supplying strip Minster, Ohio stock from a supply thereof to a feed device pertaining to a machine in which the supply system includes a [22] Flled' Sept 1972 straightening roller stand driven by a variable speed [21] Appl. No.: 286,123 drive and with an arrangement provided for maintaining a loop in the stock being supplied between the l straightening roller stand and the feed device. The [52] US. Cl 72/12, 226/42, 72/27, feed device operates intermittently to supply the stock 72/24, 72/16] to a machine and the machine supplies a signal on [51 Int. Cl. l. 1321c 19/00, B65h 23/22 each cycle that tends to increase the speed of the vari- [58] Field of Search 72/24, 27, 12, 28; 226/42 able speed drive. A feedback signal tends to reduce the speed of the variable speed drive thereby tending to maintain the aforementioned stock loop at about a [56] References Cited fixed size. When the loop exceeds a certain length, the UNITED STATES PATENTS speed of the drive is reduced, and if the loop shortens 3,236,429 2/1966 Klein 226/42 beyond a predetermined amount, the machine being 31513-523 5/1970 Mmermaier 6131 2/27 fed and the feed device and the roller stand come to a 3,584,853 6/1971 Munson 72/17 X halt 3,637,123 1/1972 Jones 226/42 16 Claims, 6 Drawing; Figures 2 P2 2 5 6040 PI 60 "3 o o @7 kw s 44 1: i p, 38 '28 1 48 I l 28b 7 r 50 l 1 i i I 54 SE I L2 U 52 2 36 t I t o CONTROL PRESS I1 0 I WINDINGS CRANKSHAFT i Q S 1 LIMIT 102 1 1:] I 90 92 5W1TCH c UTCH Eel-lemma:

I08 95 98 I00, I [Q6 94 THUMBWHEEL |NpUT V SWITCH FOR /|o4 uo FEED LENGHT ER REGlSTiER j m/Em cgfii t COMMAND STOCK SUPPLY SYSTEM The present invention relates to a system for supplying stock to an intermittently operating feed device for a machine, such as a press or the like.

Stock supply systems are known and quite often take the form of an arrangement for withdrawing strip stock from a reel thereof and supplying it to an intermittent feed device. Such supply systems quite often maintain a supply loop in the stock ahead of the feed device so that substantially continuous movement of the stock from the supply can be maintained while intermittent feeding thereof to the machine being supplied takes place.

The present invention is concerned with a stock supply system of the nature referred to but particularly adapted for use in connection with extremely high speed machines. An example of such a machine, is a press operating at speeds of up to 1,600 strokes per minute or more with a feed device attached thereto that feeds stock into the press on each stroke thereof. With such extremely high speed operation of the press and feed device, it becomes quite important to maintain the supply of stock to the feed device as uniformly as possible and to provide controls to control the speed of delivery of the stock which are sensitive to varying conditions.

With the foregoing in mind, a primary objective of the present invention is the provision of a stock supply system of the nature referred to which will maintain substantially uniform stock supply conditions under high speed operations.

Another object of the present invention is the provision of a stock supply system of the nature referred to operating in conjunction with a straightening roller stand in which the speed of operation of the straightening roller stand is subject to fine speed control.

Another object of the present invention is the provision of a stock supply system in which the stock moves at relatively high speed but wherein the supply loop in the stock disposed ahead of the feed device does not whip or cause problems in any other manner.

A still further object is the provision of a stock supply system of the nature referred to in which adjustments in the speed of delivery of the stock are made substantially continuously and in small increments thereby permitting extremely fine control of the stock delivery.

These and other objects and advantages of the present invention will become more apparent upon reference to the following detailed specification taken in connection with the accompanying drawings in which:

FIG. 1 is a schematic view of an installation according to the present invention.

FIG. 2 is a view drawn at somewhat enlarged scale showing the device of the present invention and schematically illustrating a control circuit pertaining thereto.

FIG. 3 is a more detailed schematic illustration of a control circuit pertaining to the device.

FIG. 4 schematically illustrates the variation in the supply of control signals to the variable speed drive forming a part of the installation when the control circuit of FIG. 3 is used.

FIG. 5 is a view like FIG. 4 for the control circuit of FIG. 2.

FIG. 6 shows another arrangement of the stock loop control system.

BRIEF SUMMARY OF THE INVENTION of stock is fed into the machine. The stock is received from a supply thereof which comprises a reel of the stock and a straightening roller stand through which the stock passes and which is driven to withdraw stock from the reel and to advance it toward the feed device.

Interposed between the straightening roller stand and the feed device is a space, preferably confined within a housing, in which the stock forms a captive supply loop of tightly defined size with detectors being provided to determine maximum and minimum lengths of the loop.

The straightening roller stand is driven by a variable speed drive, preferably, in the form of a constant speed motor and an eddy current clutch, and the output speed of the drive is determined by the degree of energization of the eddy current clutch. control winding. A source of energy for the eddy current clutch control winding is adjusted in conformity with a signal supplied thereto and this signal is adjusted in speed increasing direction on each cycle of the machine and is adjusted speed decreasing direction by a feedback from the straightening roller stand. The signals from the machine and the straightening roller stand are balanced against each other so that the signal to control the energy to the eddy current clutch control winding tends to maintain the supply loop in the stock at a substan tially constant length.

Preferably, the stock loop gradually increases in length until a maximum loop length is detected, whereupon the energy supply to the eddy current clutch control winding is reduced, thus, shortening the loop which will, thereupon, gradually build up again to maximum length.

If the stock loop shortens to a predetermined minimum length, the machine and the feed devices and the straightening roller stand come to a halt until proper adjustments have been made.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings somewhat more in detail, FIG. 1 schematically illustrates a machine 10 in the form of a press which has a crankshaft 12 rotatable therein, the throw 14 of which is connected by connecting rod 16 with a slide 18. Slide 18 is opposed to a bed member 20 and mounted on the slide and bed member are cooperating elements of a die set 22. Mounted on the frame of the press is a feed device 24 adapted for being driven by crankshaft 12 and operable to feed stock into the press while the parts of the die set are separated while interrupting the feed when the parts of the die set are operating on the stock disposed therebetween.

On the side of feed device 24 opposite the press frame there is a device 26 in which a captive supply loop 28 is thrown into the stock S being fed to machine 10.

On the side of device 26 opposite feed device 24 is a straightening roller stand 30 which may be of any conventional type and which, as will be seen hereinafter, includes feed rollers which are driven at variable speed. The stock S which passes through straightening roller stand 38 is derived from a reel 32 of the stock rotatably mounted on a support 34 which preferably includes a drag brake to maintain a certain degree of tension in the stock ahead of the straightening roller stand.

The crankshaft 12 of the press, as will be seen in FIG. 1, is adapted for operating a limit switch LS1 once on each rotation of the crankshaft, and this limit switch forms a control element pertaining to the control system that controls the speed of operation of the feed rollers in the straightening roller stand.

FIG. 2 shows more in detail the straightening roller stand 30 and the drive therefor and the device 26 in which the supply loop 28 of stock S is disposed. FIG. 2 also schematically illustrates at the discharge side of device 26 the feed rollers 36 pertaining to the feed device 24 and which are pressed against opposite sides of the stock S so as to be in frictional engagement therewith.

Device 26 comprises a box-like chamber 38 having an inlet opening at the top at the left side at 40 and a discharge opening 42 at the right on the bottom immediately ahead of feed rollers 36.

Mounted inside chamber 38 and leading inwardly of the chamber from the bottom of inlet opening 40 is a plate 44 forming a throat or passage through which the stock is fed ad terminating in a curved flexible end portion 46 which can serve to positively guide the stock and to prevent a sharp bend therein if the stock engages portion 46.

At the opposite side of the chamber from inlet 40 and near the top is another curved sheet 48 and which may also be flexible and which will guide the stock as the stock comes in engagement therewith.

A guide plate 50 is also mounted in the chamber 38 and at the bottom has a curved part 52 which is arranged in spaced relation to another curved flexible plate 54. Curved portion 52 and curved plate 54 define an outlet channel through which the stock passes in approaching discharge openng 42.

An important feature of the stock loop control system is that it permits the physical size of the stock loop to be held to a minimum, consistent with the allowable elastic bending stresses in the material being transported. By so proportioning the guiding surfaces of the stock loop control unit to maintain the minimum allowable radius of curvature of the material the minimum possible mass of stock is accelerated on each feeding cycle by the intermittent feed unit on the press. Minimizing the mass of stock to be accelerated permits the feed unit to experience the lowest possible accelerating loads, and thereby to achieve the maximum possible feeding rates within its rated force and torque capactities.

The positive guiding and restraint provided by the stock loop control unit also maintains the size and shape of the stock loop consistent from one press feeding cycle to the next so that nearly identical loads are imposed on the intermittent feed on each cycle of operation, helping to assure consistent feeding accuracy. The provision of flexibility in the stock guiding surfaces within the loop control unit, particularly flexible memher 54, tends to minimize the whipping action of the stock loop as it is intermittently advanced and stopped by the press feed.

Proper contouring of the stock guiding surfaces within the loop control unit can permit the end of the stock to automatically be guided through the loop control unit to provide a self-threading action, minimizing the manual effort required to thread the end of a new coil of stock from the straightener into the press.

The length of the supply loop 28 and the stock in chamber 38 is adapted for being detected by a pair of photocell-lamp combinations with lamp Lil and photocell lPl being disposed so that a certain maximum length of the stock loop will interrupt the light beam passing therebetween, whereas a lamp L2 and photocell P2 are arranged so that the light beam extending therebetween will be interrupted, except when the supply loop shortens beyond a minimum allowable length.

The normal length of supply loop is indicated at 28 while the dotted line 28A represents a maximum length loop and the dotted line 288 represents a minimum length loop. It will be understood that proximity switches or switches actuated by engagement with the stock could be provided in lieu of the lamp and photocell combinations illustrated.

It will also be apparent that lateral guiding means could be provided in chamber 38 for confining the stock passing therethrough to a certain lateral range if so desired, whereby the device would thus become adapted to different stock widths.

The straightening roller stand 30, located to the left of chamber 38 in FIG. 2, consists of upper and lower rows of straightening rollers 56 and 58, respectively, and arranged in opposed staggered relation and operable, in a known manner, to straighten stock drawn therethrough. The straightening roller stand includes opposed feed rollers 60 at the opposite ends, at least two of which carry sprockets about which a chain 62 is entrained with the said chain passing about idlers 64 and then about a driven sprocket 66.

Sprocket 66 is mounted on a shaft 68 on which is mounted a drive member 70 connected by flexible drive element 72 with output member 74 pertaining to a drive motor 76. Drive motor 76 is connected with output member 74 by way of an eddy current clutch 78 so that the coupling of motor 76 to putput member 74 can be varied by varying the supply of energy to the control winding of the eddy current clutch 78.

The aforementioned shaft 68 carries a further drive member 80 connected by flexible drive member 82 to input member 84 which drives a pulse generator 86. At this point, it will be apparent that the pulse generator 86 supplies pulses in conformity with the speed of operation of the straightening roller stand.

The eddy current clutch comprises a control winding schematically illustrated at 90 and which receives a supply of energy via line 92 from a controller 94. Upon an increase in the supply of energy from controller 94 to winding 90, the coupling of motor 76 to output member 74 is tightened, whereas upon a decrease in the supply of energy from controller 94 to winding 90, the degree of coupling of motor 76 with output member 74 is reduced. In addition to the eddy current clutch 78, coupled to output member 74, eddy current brake 79 is also coupled to the output member 74 to provide more rapid stopping of the straightener drive.

FIG. 2 also shows, quite schematically, a control arrangement by means of which the signal from controller 94 to winding 90 can be controlled. This circuit comprises thumb wheel switches schematically illustrated at 96 and by means of which a basic feed command can be set up, conforming with the amount of stock to be fed into the machine on each cycle thereof. The command from switches 96 is supplied to a gate 98 and this command is released from register 98 to the upcounting terminal of a register 100 once each cycle of the machine by a control element 102 which corresponds to limit switch LS1 of FIG. l.

The downcounting terminal of register 100 is also supplied with signals from pulse generator 84 by wire 104. From register 100, a signal is supplied to the digital to analog convertor 106 and from this convertor the signal is supplied to controller 94.

Signals are released from controller 94 in conformity with signals supplied thereto from tachometer 108 driven in unison with the straightening roller stand and connected by wire 110 with controller 94.

When loop 28 reaches a length such that the beam from L1 to P1 is interrupted, the upcount signal to register 100 is blocked for a predetermined number of counts thereby to reduce the signal to convertor 106 and slow down the rate of stock supply.

The current supply to coil 90, as controlled by the circuit of FIG. 2, is shown in FIG. 5.

A schematic view of a somewhat modified control system is illustrated in FIG. 3, wherein the clutch control winding is again indicated at 90 and the controller which supplies signals thereto is again indicated at 94. The digital to analog convertor of FIG. 2 is indicated in FIG. 3 by the same reference numeral at 106. Furthermore, the register 100 of FIG. 2 is shown at 100 in FIG. 3.

As to the remainder of FIG. 3, the thumb wheel switches shown at 96 supply signals to the register 98 as before mentioned.

The circuit of FIG. 3, however, includes a clock pulse source 112, the output from which is supplied to a phase splitter 114 which supplies pulses to wires 116 and 118 which are 180 degrees out of phase with each other.

Wire 116 is connected to a clock synchronizer 120 which receives signals from the aforementioned limit switch LS1. When a signal passes through clock synchronizer 120, it is delivered to gate 98 by wire 122 and to a normally enables gate 124 via wire 126.

The signals to gate 98 release the preset count therein to a wire 128 leading to one input of an AND gate 130, the other input of which is connected to wire 116. It will be apparent that under normal operating circumstances, each time limit switch LS1 closes, AND gate 130 will supply a signal to wire 132. Thissignal is fed back to the countdown terminal of component 98 and reduces the count therein to 0. This signal is also supplied to one terminal of a two input AND gate 134, the other terminal of which is connected to the output side of gate 124. As mentioned, gate 124 is normally enabled so that under normal circumstances gate 134 will supply a signal to an input of an OR gate 134 the output terminal of which is connected to the upcounting terminal of register 100.

The pulse generator 86 is connected via' another clock synchronizer 138 with the countdown terminal of register 1011 so that the output from register we is alternately modified in an increasing and decreasing manner.

If the supply loop in the stock becomes too long, a switch LS2 is actuated and it conforms in function to that carried out by lamp L1 and photocell P1 in FIG. 2. When switch LS2 is actuated, gate 124 is disabled and when this occurs, the next time limit switch LS1 closes, there will be no countup signal supplied to register while at the same time the countdown signals from pulse generator 86 continue. The stock loop, under these circumstances, tends to remain of a constant length, or to gradually increase in length, with periodic substantial reductions in length.

The machine or press includes a starting clutch or the like, and when starting the machine, limit switch LS3 is momentarily closed, and supplies a signal through an OR gate 140 which is connected to the reset terminal of register 100 and resets the register at 0.

The closing of jog switch 142 is also operable to supply clocking signals from a clock pulse source 113 through OR gate 140 of register 1W while also supplying a countup signal to the register to cause stock to advance in the system.

FIG. 4 schematically illustrates the course of signals supplied to eddy current clutch 90. When the press first starts up, the limit switch LS1 actuated thereby supplies signals which cause the current to coil 90 to increase in increments as indicated by the steps in FIG. 4. After the straightening roller stand commences to operate, countdown signals will be supplied which, in between increments 150 will cause a reduction in the signal to coil 90 as indicated by the lines 152.

By causing the straightening roller stand to run slightly ahead of the amount fed by feed rollers 36, the stock loop will gradually lengthen until the light beam from L1 to P1 is interrupted and it corresponds to closing of switch LS2 and which occurs at the point marked 154 in FIG. 4.

It will be seen that this interrupts the increment 150 that would normally be fed into the register and, instead, permits the feedback pulses from the pulse generator to continue to reduce the supply of current to clutch coil 90 until the supply loop shortens to the point that the light beam from L1 to P1, corresponding to the opening of LS2, is established and the cycle resumes.

It will be evident that other control systems could be provided for comparing speed up signals supplied by the press to slow down signals supplied by the straightening roller stand to maintain the supply loop and the stock substantially constant.

FIG. 6 illustrates an alternate arrangement of the stock loop control system together with the associated straightener, straightener drive, and stock reel. In FIG. 6, the same reference numerals are employed as in the previous views, where applicable, with the addition of an a.

The primary objective of this variation on the system is to reduce the floor space occupied and to provide simpler manual access for threading the end of the stock into the straightener stand from a fresh stock reel.

In the design shown the straightener stand 30a is oriented to advance stock Sa vertically therethrough and into a vertical loop 28a at the outfeeding end of the straightening stand which is confined within fixed, curved members forming guiding surfaces within the loop control unit 26a. The loop control device and the straightening roller stand of FIG. 6 will be seen to be turned 90 from the FIG. 2 position thereof, thus resulting in a more compact installation. The drive is the same as already described.

The aforementioned guiding members, and which are made like those shown in FIG. 2, are identified, generally, at 200 and 202 in FIG. 6. A further curved guide member at 204 is disposed between the take-off region of supply reel 32a and the infeeding feed rolls of straightener stand 30a.

The radii of curvature of the aforementioned stock guding surfaces are made as small as possible, consistent with bending stresses permissible in the stock to be fed without producing yielding of the material.

The loop control unit thus maintains the advantage of minimum mass of stock in the loop to minimize loads imposed upon the intermittent press feed device which draws from the stock supply loop on each press feed cycle. Stock loop detectors Lla, Pla, L2a, P2a, similar to those illustrated in FIG. 2 are employed for controlling operation of the straightener drive in the same manner as described earlier. Provision of the positive stock supply loop guiding system within the loop control unit conveys the same advantages of limiting the whipping action of the stock loop at high operating speeds and imposing a consistent and low accelerating load on the press feed device.

The several components of the FIG. 6 arrangement may be tied together in aligned relation as by a connector device 206.

It has been mentioned that the stock supply loop gradually lengthens under normal operating conditions and this is achieved by selecting the pulse generator driven by the straightening stand so that it is not precisely matched to the rate at which the feed device is operated. In short, the number of pulses supplied by the pulse generator operated by the straightening roller stand are fewer than the number of pulses added on each cycle of the press. Thus, the straightening roller stand feeds a slightly greater length of stock during each press cycle thant the feed device advances into the press.

The adjustable thumb wheel switches in FIG. 2 determine the number of pulses that are supplied for each feed length on a cycle of the press.

Modifications may be made within the scope of the appended claims.

What is claimed is:

1. In a stock supply system, especially for the high speed advancing of strip stock from a supply thereof toward a feed device for a machine having a work cycle, the feed device having a feed period and a dwell period for each machine cycle for intermittent movement of the stock into the machine; first means adapted for engaging the stock to effect continuous movement of the stock from the supply thereof toward the feed device, a continuously adjustable speed drive drivingly connected to said first means, signal operated means connected in speed controlling relation to said drive, first control means operable when actuated to supply speed increasing signals to said signal operated means and actuated once for each feed period of the feed device, second control means operable when actuated to supply speed decreasing signals to said signal operated means and actuated by said drive in conformity with the speed thereof, receiving means disposed between said first means and the feed device having inlet and outlet means through which said strip stock passes and including wall means for confining a captive supply loop in the strip stock being supplied between said feed means and said feed device, and detector means in said receiving means connected in controlling relation to said drive and operable when actuated to reduce the speed of said drive, said detector means being disposed for actuation by the captive supply loop in the stock in said receiving means when the loop exceeds a predetermined length in said receiving means.

2. A stock supply system according to claim 1 in which said first means comprises a straightening roller stand having stock feed rolls and said drive is connected to said feed rolls.

3. A stock supply system according to claim 1 in which said drive comprises a motor and variable clutch driven thereby, said control means being operable to vary said clutch.

4. A stock supply system according to claim 1 in which said first means comprises feed rolls adapted to receive the stock therebetween, said drive comprising a motor and an eddy current clutch connecting the motor to the feed rolls, said signal operated means comprising a variable source of energy connected to said clutch and supplying energy to the clutch control winding in conformity with control signals supplied to said source.

5. A stock supply system according to claim 4 which includes a register connected to said variable source to supply control signals thereto, said register having an upcounting terminal connected to said first control means and a downcounting terminal connected to said second control means.

6. A stock supply system according to claim 5 which includes means for predetennining the signal supplied by said first control means to said register.

7. A stock supply system according to claim 5 in which the stock has a supply loop therein between said feed rolls and said feed device, detector means adapted to be actuated by the stock loop when the loop exceeds a predetermined length, and means operable during actuation of said detector means for interrupting the signal from said first control means to said register whereby the signals from said second control means causes reduction in the speed of said feed rolls and shortening of the loop.

8. A stock supply system according to claim 1 in which said first means comprises feed rolls adapted to receive the stock therebetween, said drive comprising a motor and an eddy current clutch connecting the motor to the feed rolls, said signal operated means comprising a variable source of energy connected to te control winding of said clutch and supplying energy to the clutch in conformity with control signals supplied to said source, a register connected to said variable source to supply control signals thereto, said register having an upcounting terminal connected to said first control means and a downcounting terminal connected to said second control means, said first control means comprising a switch arranged to be actuated once for each feed period of said feed device, an adjustable counter having an output terminal connected to the upcounting terminal of said register and also having a control terminal, said switch when actuated supplying a signal to said control terminal to cause the count set in said counter to be released to said output terminal, said second control means comprising a pulse generator driven by said drive and connected to said downcounting terminal of said register, a supply loop in the stock between said feed rolls and the feed device and detector means positioned to be actuated in response to the loop exceeding a predetermined length, and means responsive to actuation of said detector means for preventing the supply of signals to said upcounting terminal of said register.

9. A stock supply system according to claim 1 in which said receiving means comprises a chamber having a first opening on one side to receive the stock from said straightening roller stand and a second opening on the other side to discharge the stock to said feed device, and guide means in said chamber guiding the stock passing therethrough in a curvilinear path which includes at least one loop.

10. A stock supply system according to claim 9 which includes detector means adapted for actuation upon the loop reaching a predetermined minimum length.

11. A stock supply system according to claim 9 in which said guide means includes plate elements dis.- posed on opposite sides of the path taken by said stock in said chamber.

12. A stock supply system according to claim 11 in which at least portions of at least some of said plate elements are flexible.

13. A stock supply system according to claim 9 in which said detector means comprises a lamp-photocell combination.

14. In combination; a press, a feed device for feeding stock intermittently into the press and driven by the press, a straightening roller stand adapted to withdraw stock from a supply thereof and advance the stock continuously toward the feed device, the stock having a confined captive supply loop therein between said straightening roller stand and said feed device, an infinitely variable speed drive connected to said straightening roller stand, a signal operated controller connected to said drive to vary the speed thereof, means operated by thepress on each cycle thereof for supplying sped increasing signals to said controller, means operated in synchronism with said straightening roller stand for supplying speed reducing signals to said controller, a first detector adjacent said captive supply loop actuated in response to the said loop exceeding a predetermined maximum length for interrupting the signals from said press operated means to said controller, and a second detector adjacent said captive supply loop actuated in response to the said loop reducing to below a predetermined minimum length and adapted for interrupting operation of said press and straightening roller stand.

15. In a stock supply system, especially for the high speed continuous advancing of strip stock from a supply thereof toward a feed device for a machine having a work cycle, the feed device having a feed period and a dwell period for each machine cycle; first means adapted for engaging said stock to move the stock from the supply thereof toward the feed device, an infinitely variable speed drive drivingly connected to said first means, signal operated means connected in speed controlling relation to said drive, receiving means disposed between said first means and the feed device and including means for receiving and confining a captive supply loop in the stock being supplied, and detector means in said receiving means connected in controlling relation to said drive operable when actuated to control the speed of said drive, said detector means being lo cated for actuation by the captive supply loop in the stock and controlling said drive so as to maintain the length of said captive loop between predetermined limits.

16. A stock supply system according to claim 1 in which said signal operated means includes a register having an upcounting terminal connected to said first control means and a downcounting terminal connected to said second control means.

l= =i =l provide more rapid stopping of the straightener drive.

FIG. 2 also shows, quite schematically, a control arrangement by means of which the signal from controller 94 to winding 90 can be controlled. This circuit comprises thumb wheel switches schematically illustrated at 96 and by means of which a basic feed command can be set up, conforming with the amount of stock to be fed into the machine on each cycle thereof. The command from switches 96 is supplied to a gate 98 and this command is released from register 98 to the upcounting terminal of a register 100 once each cycle of the machine by a control element 102 which corresponds to limit switch LS1 of FIG. l.

The downcounting terminal of register 100 is also supplied with signals from pulse generator 84 by wire 104. From register 100, a signal is supplied to the digital to analog convertor 106 and from this convertor the signal is supplied to controller 94.

Signals are released from controller 94 in conformity with signals supplied thereto from tachometer 108 driven in unison with the straightening roller stand and connected by wire 110 with controller 94.

When loop 28 reaches a length such that the beam from L1 to P1 is interrupted, the upcount signal to register 100 is blocked for a predetermined number of counts thereby to reduce the signal to convertor 106 and slow down the rate of stock supply.

The current supply to coil 90, as controlled by the circuit of FIG. 2, is shown in FIG. 5.

A schematic view of a somewhat modified control system is illustrated in FIG. 3, wherein the clutch control winding is again indicated at 90 and the controller which supplies signals thereto is again indicated at 94. The digital to analog convertor of FIG. 2 is indicated in FIG. 3 by the same reference numeral at 106. Furthermore, the register 100 of FIG. 2 is shown at 100 in FIG. 3.

As to the remainder of FIG. 3, the thumb wheel switches shown at 96 supply signals to the register 98 as before mentioned.

The circuit of FIG. 3, however, includes a clock pulse source 112, the output from which is supplied to a phase splitter 114 which supplies pulses to wires 116 and 118 which are 180 degrees out of phase with each other.

Wire 116 is connected to a clock synchronizer 120 which receives signals from the aforementioned limit switch LS1. When a signal passes through clock synchronizer 120, it is delivered to gate 98 by wire 122 and to a normally enables gate 124 via wire 126.

The signals to gate 98 release the preset count therein to a wire 128 leading to one input of an AND gate 130, the other input of which is connected to wire 116. It will be apparent that under normal operating circumstances, each time limit switch LS1 closes, AND gate 130 will supply a signal to wire 132. Thissignal is fed back to the countdown terminal of component 98 and reduces the count therein to 0. This signal is also supplied to one terminal of a two input AND gate 134, the other terminal of which is connected to the output side of gate 124. As mentioned, gate 124 is normally enabled so that under normal circumstances gate 134 will supply a signal to an input of an OR gate 134 the output terminal of which is connected to the upcounting terminal of register 100.

The pulse generator 86 is connected via' another clock synchronizer 138 with the countdown terminal of register 1011 so that the output from register we is alternately modified in an increasing and decreasing manner.

If the supply loop in the stock becomes too long, a switch LS2 is actuated and it conforms in function to that carried out by lamp L1 and photocell P1 in FIG. 2. When switch LS2 is actuated, gate 124 is disabled and when this occurs, the next time limit switch LS1 closes, there will be no countup signal supplied to register while at the same time the countdown signals from pulse generator 86 continue. The stock loop, under these circumstances, tends to remain of a constant length, or to gradually increase in length, with periodic substantial reductions in length.

The machine or press includes a starting clutch or the like, and when starting the machine, limit switch LS3 is momentarily closed, and supplies a signal through an OR gate 140 which is connected to the reset terminal of register 100 and resets the register at 0.

The closing of jog switch 142 is also operable to supply clocking signals from a clock pulse source 113 through OR gate 140 of register 1W while also supplying a countup signal to the register to cause stock to advance in the system.

FIG. 4 schematically illustrates the course of signals supplied to eddy current clutch 90. When the press first starts up, the limit switch LS1 actuated thereby supplies signals which cause the current to coil 90 to increase in increments as indicated by the steps in FIG. 4. After the straightening roller stand commences to operate, countdown signals will be supplied which, in between increments 150 will cause a reduction in the signal to coil 90 as indicated by the lines 152.

By causing the straightening roller stand to run slightly ahead of the amount fed by feed rollers 36, the stock loop will gradually lengthen until the light beam from L1 to P1 is interrupted and it corresponds to closing of switch LS2 and which occurs at the point marked 154 in FIG. 4.

It will be seen that this interrupts the increment 150 that would normally be fed into the register and, instead, permits the feedback pulses from the pulse generator to continue to reduce the supply of current to clutch coil 90 until the supply loop shortens to the point that the light beam from L1 to P1, corresponding to the opening of LS2, is established and the cycle resumes.

It will be evident that other control systems could be provided for comparing speed up signals supplied by the press to slow down signals supplied by the straightening roller stand to maintain the supply loop and the stock substantially constant.

FIG. 6 illustrates an alternate arrangement of the stock loop control system together with the associated straightener, straightener drive, and stock reel. In FIG. 6, the same reference numerals are employed as in the previous views, where applicable, with the addition of an a.

The primary objective of this variation on the system is to reduce the floor space occupied and to provide simpler manual access for threading the end of the stock into the straightener stand from a fresh stock reel.

In the design shown the straightener stand 30a is oriented to advance stock Sa vertically therethrough and

Claims (16)

1. In a stock supply system, especially for the high speed advancing of strip stock from a supply thereof toward a feed device for a machine having a work cycle, the feed device having a feed period and a dWell period for each machine cycle for intermittent movement of the stock into the machine; first means adapted for engaging the stock to effect continuous movement of the stock from the supply thereof toward the feed device, a continuously adjustable speed drive drivingly connected to said first means, signal operated means connected in speed controlling relation to said drive, first control means operable when actuated to supply speed increasing signals to said signal operated means and actuated once for each feed period of the feed device, second control means operable when actuated to supply speed decreasing signals to said signal operated means and actuated by said drive in conformity with the speed thereof, receiving means disposed between said first means and the feed device having inlet and outlet means through which said strip stock passes and including wall means for confining a captive supply loop in the strip stock being supplied between said feed means and said feed device, and detector means in said receiving means connected in controlling relation to said drive and operable when actuated to reduce the speed of said drive, said detector means being disposed for actuation by the captive supply loop in the stock in said receiving means when the loop exceeds a predetermined length in said receiving means.

2. A stock supply system according to claim 1 in which said first means comprises a straightening roller stand having stock feed rolls and said drive is connected to said feed rolls.

3. A stock supply system according to claim 1 in which said drive comprises a motor and variable clutch driven thereby, said control means being operable to vary said clutch.

4. A stock supply system according to claim 1 in which said first means comprises feed rolls adapted to receive the stock therebetween, said drive comprising a motor and an eddy current clutch connecting the motor to the feed rolls, said signal operated means comprising a variable source of energy connected to said clutch and supplying energy to the clutch control winding in conformity with control signals supplied to said source.

5. A stock supply system according to claim 4 which includes a register connected to said variable source to supply control signals thereto, said register having an upcounting terminal connected to said first control means and a downcounting terminal connected to said second control means.

6. A stock supply system according to claim 5 which includes means for predetermining the signal supplied by said first control means to said register.

7. A stock supply system according to claim 5 in which the stock has a supply loop therein between said feed rolls and said feed device, detector means adapted to be actuated by the stock loop when the loop exceeds a predetermined length, and means operable during actuation of said detector means for interrupting the signal from said first control means to said register whereby the signals from said second control means causes reduction in the speed of said feed rolls and shortening of the loop.

8. A stock supply system according to claim 1 in which said first means comprises feed rolls adapted to receive the stock therebetween, said drive comprising a motor and an eddy current clutch connecting the motor to the feed rolls, said signal operated means comprising a variable source of energy connected to te control winding of said clutch and supplying energy to the clutch in conformity with control signals supplied to said source, a register connected to said variable source to supply control signals thereto, said register having an upcounting terminal connected to said first control means and a downcounting terminal connected to said second control means, said first control means comprising a switch arranged to be actuated once for each feed period of said feed device, an adjustable counter having an output terminal connected to the upcounting terminal of said register and also having a control terminal, said switch when actuated suPplying a signal to said control terminal to cause the count set in said counter to be released to said output terminal, said second control means comprising a pulse generator driven by said drive and connected to said downcounting terminal of said register, a supply loop in the stock between said feed rolls and the feed device and detector means positioned to be actuated in response to the loop exceeding a predetermined length, and means responsive to actuation of said detector means for preventing the supply of signals to said upcounting terminal of said register.

9. A stock supply system according to claim 1 in which said receiving means comprises a chamber having a first opening on one side to receive the stock from said straightening roller stand and a second opening on the other side to discharge the stock to said feed device, and guide means in said chamber guiding the stock passing therethrough in a curvilinear path which includes at least one loop.

10. A stock supply system according to claim 9 which includes detector means adapted for actuation upon the loop reaching a predetermined minimum length.

11. A stock supply system according to claim 9 in which said guide means includes plate elements disposed on opposite sides of the path taken by said stock in said chamber.

12. A stock supply system according to claim 11 in which at least portions of at least some of said plate elements are flexible.

13. A stock supply system according to claim 9 in which said detector means comprises a lamp-photocell combination.

14. In combination; a press, a feed device for feeding stock intermittently into the press and driven by the press, a straightening roller stand adapted to withdraw stock from a supply thereof and advance the stock continuously toward the feed device, the stock having a confined captive supply loop therein between said straightening roller stand and said feed device, an infinitely variable speed drive connected to said straightening roller stand, a signal operated controller connected to said drive to vary the speed thereof, means operated by the press on each cycle thereof for supplying sped increasing signals to said controller, means operated in synchronism with said straightening roller stand for supplying speed reducing signals to said controller, a first detector adjacent said captive supply loop actuated in response to the said loop exceeding a predetermined maximum length for interrupting the signals from said press operated means to said controller, and a second detector adjacent said captive supply loop actuated in response to the said loop reducing to below a predetermined minimum length and adapted for interrupting operation of said press and straightening roller stand.

15. In a stock supply system, especially for the high speed continuous advancing of strip stock from a supply thereof toward a feed device for a machine having a work cycle, the feed device having a feed period and a dwell period for each machine cycle; first means adapted for engaging said stock to move the stock from the supply thereof toward the feed device, an infinitely variable speed drive drivingly connected to said first means, signal operated means connected in speed controlling relation to said drive, receiving means disposed between said first means and the feed device and including means for receiving and confining a captive supply loop in the stock being supplied, and detector means in said receiving means connected in controlling relation to said drive operable when actuated to control the speed of said drive, said detector means being located for actuation by the captive supply loop in the stock and controlling said drive so as to maintain the length of said captive loop between predetermined limits.

16. A stock supply system according to claim 1 in which said signal operated means includes a register having an upcounting terminal connected to said first control means and a downcounting terminal connected to said second control means.

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