US2286451A - Strip feeding means - Google Patents

Description

June 16, 1942.

C. M. WILLIAMSON STRIP FEEDING MEANS Filed March 5, 1940 4 Sheets-Sheet l June 16, 1942. c, w L s 2,286,451

STRIP FEEDING MEANS //V l E N 70/? GM 772m" Mm A TTORNE Y June 16, 1942. c. M. WILLIAMSON 2,286,451

STRIP FEEDING MEANS Filed March 5, 1940 4 Sheets-Sheet 5 //V l/E N TOR swa g June 16, 1942.

C. M. WILLIAM SON- STRIP FEEDING MEANS Filed March 5, 1940 4 Sheets-Sheet 4 Patented June 16, 1942 urrso ATEN FICE STRIP FEEDING MEAN 8 Colin Martin Williamson, Willesden Green, London, England 13 Claims.

This invention relates to gearing for use in apparatus in which a strip of flexible material has to be fed at moderate speed at one point intermittently in adjustable steps and at another point continuously. A typical example where such gearing is required is a continuous photographic printing and processing machine. Here a continuous paper or the like band must be fed in steps over the negative, stopped while exposure is efiected and then fed through treating baths. As the treatment time is long compared with the exposure time and the average feed rates in both sections must be equal, a considerable length is passing through the baths and it is therefore guided to and fro over rollers to keep the apparatus compact. Such a system has considerable inertia and it is therefore desirable to run as much of it as possible continuously; it is also necessary for the sake of economy of material to provide an adjustable intermittent feed to deal with different picture sizes without altering the speed in the continuous section. The object of the present invention is a compact and simple form of gearing for this purpose.

According to the invention the intermittent feed gear comprises two driving members which when the apparatus is in operation are moved continuously in opposite directions at speeds bearing definite ratios to the continuous feed, and a member which is oscillated by being clutched to the driving members alternately, the clutching being effected by a pair of adjustably spaced stops respectively adapted when the oscillating member reaches the ends of the stroke to unclutch it from the one driving member and clutch it to the other, the intermittent feed being derived from the oscillating member by the aid of a one-way coupling.

It is an obvious condition that the speeds of the driving members, the ratio of any intermedi ate gearing used and the sizes of the feeding drums or the like must be so related that the continuousand intermittent feeds are at least substantially equal; slight inequality could be allowed for by a loop between the two sections of strip material being fed. But such inequality would prevent the use of automatic cutting up of the strip as it emerges especially if only narrow margins are allowed. Quite apart from this however the clutching and unclutching of the oscillating member at the ends of its stroke of necessity takes time even though small and that time is independent of the length of stroke so that on this ground alone exact equality of average feed is. impossible at all adjustments. In

addition if as is preferred the clutches are of a positive type which can only engage in one of a series of definite positions, even though these may be closely spaced, the time of change may vary from cycle to cycle apart from the length of stroke. It is therefore preferred to make the intermittent feed produced by the mechanism above outlined definitely too fast and to introduce a friction clutch which by the action of interengaging stops on the continuous and intermittent feeds prevents the latter from overtaking the former, the clutch slipping when the stops engage. Such a clutch also helps to reduce shock each time the intermittent feed starts, and would also act as a safety device should the intermittent feed mechanism jam.

As above mentioned the clutches are preferably of positive type and are constituted by pawls, the two driving members being in the form of coaxial toothed wheels and the oscillating member of an arm pivoted coaxially with the two wheels.

It will be noted that as long as the continuous feed runs at the same rate, the shorter the intermittent feed distance the more frequent the feed periods; the apparatus must be geared and arranged so that sufiicient time is available for the necessary operation on the stationary strip material for th shortest feed adjustment provided. But for exactly the same reason an operating member such as a cam or pin actuated by the oscillating member can be used to control the said operation through an operated member eration has only to be performed during the return movement of the oscillating member means are provided to prevent the movement of the operated member by the operating member during the forward movements of the oscillating member, i. e. during the periods when the onewa coupling is conveying motion between the oscillating member and the intermittent actuating member. In the case of a cam the said means may be a pawl constituting one end of the cam and in the case of a pin the means may be a trigger, the pawl or trigger simply being moved aside on the forward movement of the cam or pin. The relative speeds of the two driving members may be given any desired ratio; it is preferred however to make the backward member the slower as this provides more time for the cam operation.

An embodiment of the invention applicable to a photographic printing and processing machine such as a plunger or switch; as however the op-' is shown by way of example in the accompanying drawings in which Figure 1 is a sectional end elevation of the complete mechanism taken on the line II of Figure 2,

Figure 2 is a sectional plan view of the complete mechanism,

Figure 3 is a side view, partly in section, of the complete mechanism,

Figure 4 is a detail of the pawl mechanism, on an enlarged scale,

Figure 5 is a detail section of a cam for actuating the pressure plate mechanism and exposure switch,

Figure 6 is a diagrammatic side View of a photographic printing and processing machine embodying the feed mechanism of the preceding figures.

For convenience the mechanism is housed in a box I which may also constitute an oil bath. A pulley 2 driven from a motor 65 (Fig. 6) drives a shaft 3 through worm gearing 4, 5. The shaft 3 carries two gear wheels 6, I which through gear wheels 8 and 9, II] respectively drive two equal sized gear wheels II, I2 in opposite directions. These wheels are freely borne on a spindle I 3 on which is keyed an arm I4. On the end of the arm is pivoted a double ended pawl I5 the ends of which are axially staggered so that one end can coact with wheel I I and the other with wheel I2 but it is also shaped so that it can coact with only one wheel at a time. As shown the wheels II, I2 have ordinary gear teeth but they could instead have ratchet teeth facing in opposite directions. The pawl is held rocked into engagement with the one or other wheel by an over centre device comprising in the illustrated example, a stirrup I6 pivoted on the same pivot as the pawls, and a compression spring I! carried on a guide pin I8 passing through a hole in the stirrup and pivoted on a pivot I9 carried by the pawl outside the pawl pivot. The extreme positions of the stirrup are limited by stops 29, 2| on the arm I4. The pawl is thrown over by the coaction of the stirrup with a pair of stops 22, 23. In the illustrated example the former is fixed and adjustment effected entirely through the latter which is carried by an arm 24 borne concentrically to the spindle I3 on a boss 25 in the box I. The position of stop 23 is adjusted from outside the box by means of a spindle 26 (arranged for instance for coupling to a remote control) and toothed wheel gearing 21, 23.

The mode of rocking of the pawl will be apparent from Figure 4. In this figure the pawl I5 is engaged with wheel I2 which must be rotating in counterclockwisedirection and has carried the arm to a position in which the stirrup has just reached stop 22. The further movement of the arm will cause the stirrup to be rocked on its pivot and when it gets just beyond the mid position the spring II will on one hand cause the stirrup to rock over suddenly until it is checked by stop 2I and will on the other hand also suddenly rock the pawl on its pivot thus disengaging it from wheel I2 and engaging it with wheel" It. The latter wheel is rotating clockwise and will carry the pawl assembly and arm I 4 in the same direction until the stirrup encounters stop 23 when the pawl is again thrown over and the arm brought back. Thus the arm I4 and the spindle I3 are oscillated, through an angle depending on the relative positions of the stops 22, 23.

To guard against the possibility of the pawl sticking when the stirrup is rocked, supplementary stops 22a and 23a are provided adjacent the stops 22, 23 in such position as to engage the pawl itself and rock it positively if necessary. Such stops together with a friction lock or the like could even be used alone but the quick-action spring device is much preferable.

To convey a continuous movement out of the box, the shaft 3 carries another gear wheel 29 meshing with a wheel 30 which is fast to a chain sprocket 3| concentric with spindle I3. To derive the intermittent movement and convey it out of the box the oscillating spindle I3 carries a chain sprocket 32 which incorporates a one-way clutch. The mechanism of the latter can be of any well known kind, for instance as used in bicycles and is therefore not illustrated. The two sprockets constitute feed actuating members and are geared by chains 59, 69 respectively to the feed rollers BI, 62 as illustrated in Fig. 6.

As above mentioned it is desirable to overgear the intermittent mechanism and provide limiting means to keep the average speed equal to that of the continuous movement. In the example illustrated, see Figure 2, the hub of sprocket 32 is free on the end of the spindle I3 and motion is conveyed to it by a friction clutch formed by a pair of discs 33, 34 keyed to the spindle, which are faced with suitable material and grip the hub between them under the action of a spring 35 whose pressure is adjustable by a nut 36. To prevent the intermittent sprocket 32 from overtaking the continuous sprocket 3I, pins 31, 33 project from the respective sprockets into one anothers path. Since the pawl and arm mechanism is such that the relative movement between the two sprockets is always less than one complete revolution these pins 31, 38 do not cause any other interference in operation.

In the example illustrated the backward movement of the oscillating spindle I3, when the sprocket 32 is stationary and the strip material in the apparatus of which the gearing is part is stationary in the printing section, is made use of to actuate a pressure pad device and exposure device. The actual pressure pad and light source form no part of the invention and can be of any convenient kind. Typical forms are diagrammatically indicated at 63, 64 respectively in Figure 6. The apparatus illustrated includes a plunger 39 for actuating the pressure pad 63 and a switch 40 for the electric light source 64. To operate the plunger 39 a cam M is fast on the spindle I3 and a roller 42 pivoted to the plunger and to an arm 43 pivoted in the box I at 44 coacts therewith. As the plunger must only be actuated in one direction of movement of the cam, the end of the cam which leads during the active movement is in the form of a pawl 45 urged towards the base of the cam by a spring 46, and the cam is grooved at 41 (see Figure 5). Thus when the cam is turning clockwise as seen in Figure 1 the roller 42 travels in the groove and when it encounters the pawl 45 it swings it up, as shown half effected in Figure 1, but when the cam turns counter-clockwise in this figure, when the roller encounters the pawl, the latter cannot yield and the roller rides up over it thus raising the plunger 39 against the action of a spring 48 on the latter and holding it up until the roller rides off the end of the hump of the cam. It will be apparent that when this cam mechanism is provided the minimum travel of the arm should be sufiicient to permit the complete cam cycle to be carried out and the fixed and movable stops arranged accordingly. It will also be understood that the inoperative movement shown half completed in Figure 1 must continue far enough for the cam follower to clear the pawl and allow it to swing down to the base of the cam before the latter starts its counter-clockwise movement.

The switch 40 is actuated from a pin 49 projecting from the cam 4|. The switch shown is of a type commercially obtainable in which actuation require quite small pressure acting on a button 48a which moves through a very small distance indeed, say a thousandth of an inch. This switch is pivoted at 50 and a pair of arms 5| on a spindle 52 engage beneath pins 53 on the switch. On one end of the spindle 52 is fast an arm 54 which is urged by a spring 55 towards a pin 55 projecting from a long trigger 51 loosely pivoted on the spindle 52, the lower end of the trigger pivoted on the spindle 52 and normally held by a dead centre spring I51 so that the lower end of the trigger is in the path of the pin 49. The switch mechanism is completed by an eccentric 58 pivoted above the button 40a and adapted to be rotated from outside by any suitable control member and to be retained as set by friction springs 59. When out of action the switch rests on an adjustable stop 60 but when the cam rotates clockwise in Figure 1 the pin 49 engages the trigger 5'! and as the trigger is swung clockwise the arms 5| through the pins 53 tilt the switch on its pivot until the button 40a engages the eccentric 58 and is then depressed, the spring 55 being strong enough to overcome the spring within the switch. Beyond this the switch cannot go and further movement of the trigger causes the pin 56 to leave the arm 5 the trigger continuing to move until the path of the pin 49 carries it out of engagement with the trigger when the switch and its mechanism return to the out of action position. It will be understood that the time of exposure will depend on the distance the switch has to be raised to cause depression of the button 40a so that the eccentric 58 affords a means of adjusting the exposure. The range of adjustment and position of the pin 49 are arranged so that the exposure takes place while the pressure pad 63 is in action. When the cam 4! is making its backward movement the pin 49 simply swings the trigger aside against the action of spring I51 until the pin disengages the trigger, without effect on the switch. It will be understood that various modifications can be made without departing from the scope of the invention. For example instead of the driving members being in the form of wheels they could be in the form of endless bands or chains. Again instead of the pawl device friction clutches could be used. Also in connection with the cam and trigger, the pawl arrangement could be on the cam follower instead of on the cam, and the trigger arrangement on the cam.

What I claim is:v

1. Apparatus for producing a constant feed at one point of a strip of flexible material, and an intermittent feed at another point of the same strip, the average rates of the two feeds being substantially equal, including a constant speed actuating member, a pair of juxtaposed driving members, means moving said juxtaposed members in opposite directions at speeds bearing fixed ratios to the speed of said constant speed member, an oscillating member, means for clutching said oscillating member to either of said driving members, two adjustably spaced clutch reversing members coacting with said oscillating member to declutch said oscillating member from the one driving member and clutch it to the other thereby reversing the motion of said oscillating member at determined points, a final intermittent actuating member, and fixed ratio gearing including a one way coupling between said oscillating member and said final intermittent feed member.

2. Apparatus as set forth in claim 1 wherein the several fixed ratios are such that said intermittent actuating member tends to overtake said constant speed member, said apparatus also including a friction clutch in the intermittent gearing and interengaging means on an intermittent and a continuous member preventing said intermittent actuating member from overtaking said constant speed member.

3. Apparatus for producing a constant feed at one point of a strip of flexible material and an intermittent feed at another point of the same strip, the average rates of the two feeds being substantially equal, comprising a source of constant rotation, a constant speed actuating member geared thereto a fixed ratio, a pair of oppositely rotating driving members geared to said source at fixed ratios, oscillating means clutchable to either of said oppositely rotating members, an intermittent actuating member having one way connection with said oscillating means, and a pair of throw over members at adjustable spacing in the path of said oscillating means adapted to transfer its engagement from that of said driving members which moves it towards said throw over member to the other of said driving members.

4. Apparatus as set forth in claim 3 wherein said driving members are toothed wheels and said oscillating means is clutchable thereto by means of pawls.

5. Apparatus as set forth in claim 3 wherein said driving members are coaxial toothed wheels, said oscillating means comprises an arm pivoted coaxially therewith, and said arm is clutohable thereto by means of a double ended pawl pivoted thereon.

6. Apparatus for producing a constant speed at one point of a strip of flexible material and an intermittent feed at another point of the same strip, the average rates of the two feeds being substantially equal, comprising a source of constant rotation, a constant speed actuating member geared thereto at fixed ratio, a pair of oppositely rotating coaxial toothed wheels geared to said source at fixed ratios, an arm pivoted coaxially to said toothed wheels, a double ended pawl pivoted on said arm so as to be rockable into engagement with either of said toothed wheels but only one at a time, an over centre device holding said pawl in engagement with one or other of said wheels, a pair of stops at adjustable spacing in the path of said over centre device whereby said pawl is rocked over when said over centre device encounters either of said stops, an intermittent actuating member and means including a one way clutch coupling said arm to said intermittent actuating member.

'7. Apparatus as set forth in claim 6 wherein said constant speed actuating member and said intermittent actuating member are coaxial, and the fixed gear ratios are such that said intermittent actuating member tends to overtake said constant speed member, said apparatus also in cluding a friction clutch in the transmission leading to said intermittent actuating member, and a stop on each of said actuating members, said stops projecting into one anothers path so that said intermittent actuating member is checked when it catches up with said constant speed member.

8. Apparatus as set forth in claim 1 also including an operating member positively oscillated by said oscillating member, an operated member movable by said operating member, means preventing movement of said operated member by said operating member during the periods when said one Way coupling is conveying motion between said oscillating member and said final intermittent actuating member, and means actuated by said operating member for controlling a desired operation on the strip.

9. Apparatus as set forth in claim 1 also including a cam rigid with said oscillating member, a cam follower for cooperation with said cam and adapted to control a desired operation upon the strip, said cam being grooved so that the cam can pass the follower Without actuating it, and a pawl pivoted on said cam at the end which leads during the periods when said intermittent actuating member is stationary, and means biasing said pawl into a position which closes the groove in said cam.

10. Apparatus as set forth in claim 1 also including a pin rigid with said oscillating member, a pivoted trigger lying in the path of said pin and adapted to control a desired operation upon the strip, an arm pivoted to said trigger, and yieldable means normally holding said arm in a definite position in relation to said trigger.

11. In apparatus for producing a constant feed at one point of a continuous strip of flexible material and an intermittent feed at another point of the same strip, the combination of a continuous speed actuating member, means for rotating said actuating member, an intermittent actuating member coaxial with said continuous speed actuating member, adjustable step rotational means affording a rotational movement having an intermittent and excessive relationship to the rotation of said continuous speed actuating member, a friction clutch coupling said rotational means and intermittent actuating member, and a stop on each of said continuous and intermittent actuating members projecting into each others path.

12. Apparatus for producing a constant feed at one point of a strip of flexible material and an intermittent feed at another point of the same strip, the average rates of the two feeds being substantially equal, including a constant speed actuating member, a variable stroke oscillating member having a stroke time substantially in inverse proportion to its stroke, an intermittent actuating member, and transmission means including a one-way clutch coupling said oscillating member and said intermittent actuating member.

13. Apparatus for producing a constant feed at one point of a strip of flexible material and an intermittent feed at another point of the same strip, including a constant speed feed actuating member, an intermittent feed actuating member, means for drivingsaid intermittent member at an excessive average speed in relation to said constant speed member, a slippable clutch in said driving means, and means causing said clutch to slip each time the movement of said intermittent member has relatively equalled the movement of said constant speed member.

COLIN MARTIN WILLIAMSON.

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