US3857312A

US3857312A - Low drag variable demand strip feed

Info

Publication number: US3857312A
Application number: US00395368A
Authority: US
Inventors: P Carlstedt
Original assignee: Cx Corp
Current assignee: Cx Corp
Priority date: 1973-09-07
Filing date: 1973-09-07
Publication date: 1974-12-31
Anticipated expiration: 1991-12-31
Also published as: IT1016661B; FR2243135A1; DE2430105A1; NO742087L; JPS5056939A

Abstract

Variable feed rate demand of a strip material receiving or utilization device is accommodated at low drag by drawing strip material from one side of a running slack loop thereof which is formed between a guide and an opposing continuously rotated frictional feed roll. Frictional driving contact of the opposite side of the running slack loop with the feed roll is established or increased when the receiving device pulls strip material from the loop, thereby shortening the loop and by the resultant resilient reaction of the loop material pressing the loop side against the feed roll and causing feed roll to draw additional material from the supply reel or other source, overcoming the effects thereof in terms of inertia, momentum and friction.

Description

United States Patent 1 Carlstedt LOW DRAG VARIABLE DEMAND STRIP FEED [75] Inventor: Paul A. Carlstedt, Seattle, Wash. [73] Assignee: CX Corporation, Seattle, Wash. [22] Filed; Sept. 7, 1973 [21] App]. No.: 395,368

3/1971 Fredrick et al. 226/34 Dec. 31, 1974 Primary Examiner-J. M. Meister Attorney, Agent, or FirmChristensen, OConnor, Garrison & Havelka 57 ABSTRACT Variable feed rate demand of a strip material receiving or utilization device is accommodated at low drag by drawing strip material from one side of a running slack loop thereof which is formed between a guide and an opposing continuously rotated frictional feed roll. Frictional driving contact of the opposite side of the running slack loop with the feed roll is established or increased when the receiving device pulls strip material from the loop, thereby shortening the loop and by the resultant resilient reaction of the loop material pressing the loop side against the feed roll and causing feed roll to draw additional material from the supply reel ,or other source, overcoming the effects thereof in terms of inertia, momentum and friction.

l2Claims, 2 Drawing Figures BACKGROUND OF THE INVENTION This invention relates to strip feed apparatus wherein drawing of elongated strip material of indefinite length from a supply roll or other source at variable rate and at low drag is made possible by interposing between the source and the utilization device a novel feed mechanism which overcomes the effects of inertia, momenturn and friction of a rotationally mounted heavy supply roll or other source of strip material by providing a running slack loop of strip material from which the utilization device draws its requirements. The invention is herein illustratively described by reference to the presently preferred embodiment thereof applied to customer print cutting and packaging mechanisms used in commercial photographic processing laboratories; however, it will be recognized that certain modifications or changes therein with respect to details may be made and that other applications thereof are contemplated within the intended scope of the invention In commercial photographic processing laboratories, as in a variety of analogous applications to which the invention is applicable, a process or apparatus function starts or continues with unwinding a roll of strip material such as photoprint paper carrying successive photographic prints to be severed and packaged. In a commercial processing laboratory the supply roll strip of prints may be several hundred feet long or longer and initially ten inches or more in diameter, weighing several pounds. Thus, in order to draw the paper from the roll to feed the print cutter and packager mechanism requires overcoming a substantial amount of inertia and friction, and allowing for momentum of the rotating roll of print paper to prevent overrun and fouling of the system, effects which are usually of a magnitude beyond the capabilities of the low drag feed devices available in commercial cutting and packaging mechanisms. At commercial production rates, these cutting and packaging mechanisms must be fed and operated very rapidly and with great positional precision so that the successive prints are severed precisely along a midline between adjacent prints, with each cut of the knife being followed instantly by extremely rapid acceleration and deceleration of the strip so as to advance it to and stop it at the next cutting position, the process repeating several times per second. To avoid marring or tearing the paper in moving the strip in that manner the cutter feed can exert only light pull on the strip. Therefore, to work satisfactorily a slack length of the strip is made continuously available to the cutter feed and is replenished continuously as the cutter feed draws it in. The present invention is concerned with a new and improved means and technique for accomplishing this function by drawing strip material from the supply roll or other source at a rate which continuously supplies the demand of the cutter feed and without regard to the effects of friction, inertia and momentum.

Several mechanical feeder systems have been proposed heretofore in order to deliver photographic print strip material to cutting and packaging mechanisms but these generally use servos or mechanical sprocket drives coordinated in some manner with the cutter feed, and have proved to be expensive, complex and often subject to mechanical difficulties.

A broad object of this invention is to provide a new and improved, simplified and more reliable means to draw strip material from a source subject to the effects of momentum, inertia or friction or a combination thereof and to make the strip of material available at low drag and in such a manner as to meet a widely variant demand rate such as is encountered by a photoprint cutter and packaging device. In accomplishing this result the invention provides a novel means to form'a running slack loop of strip material from which the utilization or receiving device such as the cutter draws its requirements and'into which loop additional material is intermittently or continuously fed as necessary in order to maintaion a slack loop of adequatelength available as a source of material accommodating the requirements of the utilization device.

Specifically, it is a further object hereof-to achieve the foregoing purpose without the expense or complexities of prior mechanisms such as servo devices, or the like, to form a slack amount of strip material by physically or otherwise sensing a change in position or tension in the strip material-at some point in the line of feed and operating a servo motor or other means in response thereto so as to draw additional strip material from the roll or other source as needed.

Still another object of this invention, considering its application to photoprint cutting and packaging systerns, is to provide an improved feed wherein the emulsion surface of a photoprint strip is inherently pro-" tected against damage by obviating any need for physical contact between the emulsion surface and any, element of the feed mechanism. A related and further object is to devise a variable demand low drag feed means which operates without danger of tearing or jamming of the strip material being fed and which has the inherent capability of accommodating widely varying average and instantaneous rates of feed of the strip material demanded by the receiving or utilization device associated therewith.

Achieving the foregoing objectives in a very simple manner, at low initial'and operating costs and in such a manner as to facilitate insertion and removal of the strip material by an operator are further considerations and purposes of this invention.

SUMMARY OF THE INVENTION a continuously driven feed roll. The resultant frictional engagement with the feedroll, turning in the proper direction as it is, causes additional strip material to be drawn from the supply roll and fed into the loop so as i to relengthen or replenish, and thereby relax the loop. Thus the loop is continuously replenished only as and to the extent needed in order to satisfy the variable demand rate ofthe cutter mechanism, and the necessary amount of slack strip material is thus maintained at all times in readiness for supplying the demand requirements of the utilization device. Only the slight frictional drag of the strip material being drawn from one side of the running slack loop and the very negligible inertia of the length of material extending from that side of the loop to the utilization deviceneed be overcome in order to draw additional material into the utilization device. On the other hand the inertia and friction effects encountered in rotatively unwinding strip material from the supply roll for injection into the running slack loop are borne substantially entirely by the impositive frictional tractive effort of the rotated drive roll bearing against the non-emulsion face of the photoprint paper. The system is thus protective of the emulsion surface and of the paper itself, and is inherently self-regulated in that both the instantaneous and average demand rates of the utilization device are accommodated without requirement for any special sensing or follow-up servo means.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of the presently preferred embodiment of the novel feed mechanism.

FIG. 2 is a side elevation of the feed mechanism and an associated utilization device such as a photoprint cutter and packaging device shown in block. for purposes of easy illustration.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawings, a supply roll of photoprint strip material has a hollow center enabling it to be hung on a horizontal stationary support shaft 12 which is cantilevered laterally from the upper end ofa support arm I4 mounted on a base 16. The base 16 projects up from one side of a support table 18 which serves as a strip loop support and guide. The support table extends generally in the plane of feed, which occurs in the direction of arrow 20, in this instance in a horizontal plane leading to a receiving or utilization device 22 such as photoprint cutter and packaging mechanism which incorporates its own feeding means of the nature previously mentioned. The feeding means incorporated in the device 22 is assumed to be of such a nature that it requires strip material to be made available to it at low dragand in quantities satisfying variable demand rates, with minimal effects of momentum and inertia to be overcome. It is to supply these requirements of the utilization device that the illustrated embodiment of the invention is directed.

As further illustrated, the guide table 18 extending toward the cutter 22, in this case horizontally in a location generally beneath the cantilever support shaft 12, has a rearward extension 180 with an upturned end portion 180 which serves as a loop 'stop or retainer assuring that the running slack loop 10a of photoprint strip material does not become unduly lengthened and spill off the end of the support table 18.

Strip material drawn from the supply roll 10 is drawn downwardly in a variably tensioned stretch or run 1012 and passes around and under the feed roll 24 toward the stop 18a. The periphery of feed roll 24 is spaced a short distance above the top side of the support or guide table 18 to form a gap G therebetween. The surface of the drive roll 24 has suitable frictional elements or material 24a thereon. such as the rubber bands 24a located at intervals along its length, which are capable of making frictional contact with the back or upper such that when the material is pressed against these bands the frictional engagement is sufficient to create adequate traction to draw strip material from the roll 10 rotationally supported on the shaft 12. In extending toward backing plate 18a the strip material is curved downwardly and then forwardly toward the cutter 22 supportedon table 18, and thereby forms the running slack loop 10a, again passing beneath the drive roll 24.- Thus, the two sides of therunning slack loop 10a are caused to pass through the gap G and the variablelength running slack loop itself is thereby trapped between that gap and the backstop 18a.

A motor device 26 continuously rotates the feed roll 24 in such a direction that frictional contact pressure of the drive roll with the upper side of the loop passing around it with a partial wrap draws material from the roll 10. The speed of rotation and thereby the peripheral speed of the drive roll 24 is made sufficiently high that no matter what the demand rate of the utilization device 22 may be the feed roll is capable of acting at sufficient speed to supply additional strip material to replenish and maintain the running sla'ckloop 100 as needed. Obviously, this speed requirement will vary with different applications of the invention and there is therefore no specific range or velocity of rotation to be indicated.

It will be noted that the drawing of strip material from the lower side of the running slack loop 100 by the utilization device 22 instantaneously and temporarily shortens the loop, that is, it tightens or compresses the bight of the loop by drawing it wedgingly into the gap G. As it does this, there is a progressively increasing resilient reaction or recoil force resulting from resilient stiffness of the loop pressing its upper side back against the frictional surface of the drive roll 24. It is this recoil or resilient reaction effect of shortening the loop that produces the friction force of the upper side of the loop against the drive roll sufficient so as to automatically cause continued turning of the drive roll to pull additional strip material from the supply roll 10 so as to relengthen the loop once again. Thus, whatever material is drawn from the running slack loop 104 by the utilization device 22 is automatically restored by the reactive effect thereof in the shortening of the loop to produce additional material made available for additional demands of the utilization device. Moreover, the instantaneous and average demand rates are satisfied in this manner by the inherent'response of the system to their variations. For example, if an unusually large amount of material is drawn by device 22 at unusually high rates from the lower side of the loop this causes the greatest shortening of the loop and thereby the greatest increase of pressure of contact of the upper side of the loop against the drive roll 24. As a consequence there will be less slippage of the traction surface of the drive roll on the upper side of the loop and greater'and more extended force exerted on the stretch of material 10b in order to rotate and pull additional material from the supply roll1'0.

It will be noted in FIG. 1, for example, that the supply roll 10 has an open center larger than the diameter of the support shaft 12. Moreover, the support shaft 12 may or may not be rotative. If non-rotative, frictional restraint is exerted on thesupply roll 10 to be overcome in turning the roll 10 as strip material is unwound y from it. However, some friction is desirable in that it (non-emulsion) side of the strip of photoprint material, I

tends to prevent excessively prolonged rotation once started by pulling on the stretch 10b, by braking or checking overrunning through momentum. Thus, this frictional effect offsets a momentum andprovides an automatic damping effect. If desired, a rotational shaft supporting the supply roll may be provided in which case it may be desirable to provide a frictional brake or restraint on the shaft to offset the effects of momentum. Moreover, it will be seen that a small enlargement or stop 12a on shaft 12 is provided which engages the outer face of roll 10 opposite the standard 14 so as to prevent the roll from accidentally working its way off the end of the shaft 12. This is a minor detail and it is obvious that other arrangements may be utilized to support the roll or to supply strip material to the drive roll which, with the opposing guide 18, maintains the running slack loop for the benefit of the low-force feed in the utilization device 22.

It will also be evident that the location of the shaft 12 while shown to be directly above the axis of the drive roll 24, that is, in the same common vertical plane. therewith, is not necessarily required to be as depicted. For example, the support shaft 12 may be located nearer to the backstop 18a than the shaft 24 and thereby increase the angle of wrap of the strip material around the drive roll 24 in passing from the stretch 10b into the upper side of the running slack loop 10a. Such an increased angle of wrap tends to increase the total tractive effort harnessed with a given friction force applied to draw additional material from the supply roll 10 when the running slack loop 10a is shortened in the process of drawing material from it into the utilization device.

It will also be evident, that the horizontal guide surface 18 need not be horizontal but may be inclined one way or the other and that in some cases the system may be turned on edge so that the shaft 12 and the drive roll 24 rotate on vertical axes and the guide 18 is vertical. The same principle of operation would be available regardless of orientation of the plane of material departing from the running slack loop or of the plane of material entering the running slack loop around the feed roll 24.

In FIG. 2 there is shown in broken lines a floating or free, captive rotational cylinder or tube T which is received within the running slack loop 10a. This lightweight element is ordinarily not necessary to prevent accidental excessive shortening of the slack loop to the point where it is actually drawn out through the gap G. However, if for any reason something happens to bind or lock the supply roll 10 against rotation or otherwise to prevent the self-regulating action of the system to maintain the running slack loop intact, the floating element T will automatically prevent the slack loop from being drawn through the gap G.

These and other variations and embodiments of the invention will be evident from an understanding of the principle of operation described.

What is claimed is:

1. Apparatus wherein strip material of resilient stiffness is supplied and received by progressive endwise movement of the strip, comprising supply means from which strip material may be forcibly drawn, strip receiving means operable to draw strip material to it at variable rate but operable with a drawing force below that required to draw the strip material from the supply means at such variable rate, and strip feed means acting on the strip material intermediate said supply and receiving means comprising a substantially constantly rotated first element having a peripheral portion frictionally engageable with one face of the sheet strip and by such engagement operable to draw sheet strip material forcibly from the supply means, and a second element stationed adjacent to the first element across a gap to permit forming a running slack loop of the strip with the sides of such loop passing between such elements and the width of the base of such loop exceeding the width of the gap, the first and second elements being so positionally related that incidence of the strip from the supply means to a first side of the loop requires deflection of the strip partially around the peripheral portion of the first element, and departure of the strip from the opposite side of the loop toward the receiving means moves it across the second element, whereby drawing of the strip from said opposite side of the loop toward the receiving means shortens the loop and as a result of such shortening together with the resilient stiffness of the loop forces the first side thereof into frictional en gagement with the peripheral portion of the first element so as to draw more strip material from the supply means and thereby relengthen the loop. I

2. The apparatus defined in claim 1 wherein the second element comprises a strip supporting guide table upon which rests said opposite side of the loop in generally horizontal position.

3. The appartus defined in claim 2, wherein the first element comprises a power driven roller having a generally cylindrical peripheral portion with frictional means thereon.

4. The apparatus defined in claim 2, wherein the receiving means comprises a photoprint strip' cutter mechanism generally aligned with said guide table and operable to draw strip material in successive intermittent movements, and the supply means comprises a rolled strip rotational support mounted generally above said guide table.

5. in strip feed apparatus, in combination with supply means to carry and deliver strip material having resilient stiffness and indefinite length, a first feed means operable to draw the strip material at variable rate, a second feed means preceding the first feed means and operable to draw strip material'from the supply means in response to drawing of strip material by the first feed means, said second feed means forming a running slack loop of the strip material one side of which extends to the first feed means to be drawn freely thereby and the other side of which extends to'the supply' means, said second feed means comprising an independently driven rotative element and an opposing strip guide element so positionally related to the rotative element as to capture and hold said loop with the sides of the loop passing between the elements and the base of the loop maintained by its resilient stiffness wider than the spacing between said elements, the rotative element being 'frictionally engageable with the strip in reactive response to shortening of the loop by the first feed means so as to thereby draw strip material from the supply means to relengthen the loop.

6. The apparatus defined in claim 5, wherein the strip guide element is a stationary element slidably engageable with the -strip and the rotative element is positioned relatively to deflect the strip with a partial wrap around it into the loop.

7. In a strip feed apparatus, in combination with supply means to carry and deliver strip material having resilient stiffness and indefinite length, a first feed means operable to draw the strip material at variable rate, a second feed means preceding the first feed means and operable to draw strip material from the supply means in response to drawing of strip material by the first feed means, said second feed means includingopposing elements forming a running slack loop of the strip material, one side of which extends to the first feed means to be drawn freely thereby and the other side of which extends to the supply means, one element of said second feed means comprising a continuously rotated friction roll slidably engageable with the strip on one side of the loop and operable in direct reactive response to shortening of the loop, causing the strip to press more forcibly against said friction ,roll thereby to draw strip material from the supply means so as to relengthen the loop.

8. The method of feeding strip material at instantaneously variable rate with the strip drawn from a supply at a different instantaneous variable rate, comprising the steps of forming a slack running loop of the strip,

v guiding one side of the loop to be drawn at the variable rate thereby to shorten the loop, and frictionally engaging the strip with a continuously rotated friction surface in extending from the source into the opposite side of the loop, thereby to effect feeding of the strip into the loop by increased traction of said friction surface thereon in direct reactive response to such shortening of the loop so as to draw additional strip from the supply and thereby to relengthen the loop.

9. The method defined in claim 8 wherein the frictional engagement in reactive response to shortening of the loop is derived by reacting the increasing resilient force of compression of shortening of the loop against a frictional feed element and an opposing low-friction guide surface spaced across a gap from such feed element narrower than the resiliently maintained base width of the shortened loop.

10. Themethod defined in claim 9 wherein withdrawing of the loop through the gap is prevented by placing a relatively incompressible captive cylindrical element within the loop which is free to revolve and shift with shortening and lengthening of the loop.

11. In photoprint strip automatic feeding and print cutting apparatus and the like including first means to rotatively support a supply roll of processed photoprint strip from which the strip may be pulled, second means operable to feed the strip at a rapidly variablerate for the cutting of prints requiring strip acceleration rates of which the second means are substantially incapable if worked directly against the inertia and drag of the supply roll on the first means, and third means operatively interposed between the first and second means and maintaining a continuous running slack loop of the strip which is materially shortened as strip material is drawn from one side of the loop by the second means, said third means including opposing elements relatively positioned to bear against opposite sides of the loop 12. The combination defined in claim 11, wherein the second element of the third means comprises a lowfriction stationary guide means across which the strip on one side of the loop is drawn slidably-by the second means.

Claims

1. Apparatus wherein strip material of resilient stiffness is supplied and received by progressive endwise movement of the strip, comprising supply means from which strip material may be forcibly drawn, strip receiving means operable to draw strip material to it at variable rate but operable with a drawing force below that required to draw the strip material from the supply means at such variable rate, and strip feed means acting on the strip material intermediate said supply and receiving means comprising a substantially constantly rotated first element having a peripheral portion frictionally engageable with one face of the sheet strip and by such engagement operable to draw sheet strip material forcibly from the supply means, and a second element stationed adjacent to the first element across a gap to permit forming a running slack loop of the strip with the sides of such loop passing between such elements and the width of the base of such loop exceeding the width of the gap, the first and second elements being so positionally related that incidence of the strip from the supply means to a first side of the loop requires deflection of the strip partially around the peripheral portion of the first element, and departure of the strip from the opposite side of the loop toward the receiving means moves it across the second element, whereby drawing of the strip from said opposite side of the loop toward the receiving means shortens the loop and as a result of such shortening together with the resilient stiffness of the loop forces the first side thereof into frictional engagement with the peripheral portion of the first element so as to draw more strip material from the supply means and thereby relengthen the loop.

4. The apparatus defined in claim 2, wherein the receiving means comprises a photoprint strip cutter mechanism generally aligned with said guide table and operable to draw strip material in successive intermittent movements, and the supply means comprises a rolled strip rotational support mounted generally above said guide table.

5. In strip feed apparatus, in combination with supply means to carry and deliver strip material having resilient stiffness and indefinite length, a first feed means operable to draw the strip material at variable rate, a second feed means preceding the first feed means and operable to draw strip material from the supply means in response to drawing of strip material by the first feed means, said second feed means forming a running slack loop of the strip material one side of which extends to the first feed means to be drawn freely thereby and the other side of which extends to the supply means, said second feed means comprising an independently driven rotative element and an opposing strip guide element so positionally related to the rotative element as to capture and hold said loop with the sides of the loop passing between the elements and the base of the loop maintained by its resilient stiffness wider than the spacing between said elements, the rotative element being frictionally engageable with the strip in reactive response to shortening of the loop by the first feed means so as to thereby draw strip material from the supply means to relengthen the loop.

6. The apparatus defined in claim 5, wherein the strip guide element is a stationary element slidably engageable with the strip and the rotative element is positioned relatively to deflect the strip with a partial wrap around it into the loop.

7. In a strip feed apparatus, in combination with supply means to carry and deliver strip material having resilient stiffness and indefinite length, a first feed means operable to draw the strip material at variable rate, a second feed means preceding the first feed means and operable to draw strip material from the supply means in response to drawing of strip material by the first feed means, said second feed means including opposing elements forming a running slack loop of the strip material, one side of which extends to the first feed means to be drawn freely thereby and the other side of which extends to the supply means, one element of said second feed means comprising a continuously rotated friction roll slidably engageable with the strip on one side of the loop and operable in direct reactive response to shortening of the loop causing the strip to press more forcibly against said friction roll thereby to draw strip material from the supply means so as to relengthen the loop.

8. The method of feeding strip material at instantaneously variable rate with the strip drawn from a supply at a different instantaneous variable rate, comprising the steps of forming a slack running loop of the strip, guiding one side of the loop to be drawn at the variable rate thereby to shorten the loop, and frictionally engaging the strip with a continuously rotated friction surface in extending from the source into the opposite side of the loop, thereby to effect feeding of the strip into the loop by increased traction of said friction surface thereon in direct reactive response to such shortening of the loop so as to draw additional strip from the supply and thereby to relengthen the loop.

10. The method deFined in claim 9 wherein withdrawing of the loop through the gap is prevented by placing a relatively incompressible captive cylindrical element within the loop which is free to revolve and shift with shortening and lengthening of the loop.

11. In photoprint strip automatic feeding and print cutting apparatus and the like including first means to rotatively support a supply roll of processed photoprint strip from which the strip may be pulled, second means operable to feed the strip at a rapidly variable rate for the cutting of prints requiring strip acceleration rates of which the second means are substantially incapable if worked directly against the inertia and drag of the supply roll on the first means, and third means operatively interposed between the first and second means and maintaining a continuous running slack loop of the strip which is materially shortened as strip material is drawn from one side of the loop by the second means, said third means including opposing elements relatively positioned to bear against opposite sides of the loop and forming a gap of predetermined width substantially less than the width of the loop, one such element comprising a continuously rotated friction roll relatively disposed for partial enwrapment by the strip leading from the first means into one side of the loop, and the other such element being disposed to guide the opposite side of the loop as it is drawn by the second means.

12. The combination defined in claim 11, wherein the second element of the third means comprises a low-friction stationary guide means across which the strip on one side of the loop is drawn slidably by the second means.