Device and method for applying adhesive tape

Abstract: A device is disclosed for applying differential adhesion double-sided adhesive tape to the winding core of a photographic web processing machine. The device comprises first and second applicator rollers (1,2), a support (16) for a supply (18) of double-sided adhesive tape (20), the support (16) being so positioned to allow a run of adhesive tape (20) from the supply (18) to the first applicator roller (1) and thence to the second applicator roller (2), means (A) for moving each applicator roller into and out of engagement with the winding core (50) and means (28) for moving the second applicator roller (2) relative to the first applicator roller (1).

Description: BACKGROUND TO THE INVENTION Field of the invention The present invention relates to a method for applying adhesive tape to the winding core of a web processing machine in general, and photographic web treatment apparatus in particular. Description of the prior art Photographic sheet materials are often manufactured in the form of a web which is wound onto a winding core. The winding core is usually positioned at the end of the coating or processing machine. As one core becomes full, it is necessary to replace it and insert an empty core onto which further processed web may be wound. Processing machines are operated at high speed for reasons of economy and it is desirable not to have to stop or slow down the processing while winding cores are changed. Such processing machines therefore may include devices for cutting the processed web, moving a full core out of position and moving an empty core into position automatically and at high speed. The cut end of the web has to be reliably adhered to the empty winding core and in the past this has been achieved by the application of adhesive to the winding core before it is moved into position. Such a process is described for example, in United States patent no 4 422 586 (Tetro/The Black Clawson Company), where a strip of adhesive is applied along the length of a winding core for this purpose. Since the photographic sheet material is cut while the machine continues to run, by running of a cutting blade across the web of sheet material, an angled cut is produced. The fresh end of the web is therefore angled in a predetermined manner and it is important to ensure that the point of this angle is reliably adhered to the empty winding core. Thus, it is appropriate to apply a circumferential line of adhesive to the winding core at an appropriate position along its length. The strip of adhesive may be in the form of a length of double-sided adhesive tape, applied to the winding core. The double-sided tape is applied by an operator using a hand-held tape dispenser comprising first and second applicator rollers and a support for a supply of adhesive tape, the support being so positioned to allow a run of adhesive tape from the supply to the first applicator roller and thence to the second applicator roller, with an adhesive side facing outwardly. In applying the tape, certain conditions have to be satisfied. The leading edge of the adhesive tape has to be applied to the winding core by hand. The winding core must rotate by at least one revolution to obtain a complete encirclement of the winding core by the tape. The tape must be positioned at exactly the correct position along the length of the core. All these conditions are difficult to ensure under low-light conditions or in darkness. Object of the invention It is therefore an object of the present invention to provide a method for applying adhesive tape to a winding core in a fast and reliable manner. Statement of the Invention According to the present invention, a method for applying adhesive tape to the winding core of a web processing machine by means of a device comprising : support means for a first and second tape applicator roller and a roll of adhesive tape, the support means being so arranged to allow a run of adhesive tape from the roll to the first applicator roller and thence to the second applicator roller; means (A) for moving both applicator rollers into and out of engagement with the winding core; and means for moving the second applicator roller relative to the first applicator roller; which method comprises moving the first and second applicator rollers into engagement with the winding core; and moving the second applicator roller away from the first applicator roller while maintaining engagement with the winding core, thereby to apply the free end of the double-sided adhesive tape thereto; characterised by the following steps : (i) using differential double-sided adhesive tape. (ii) moving the second applicator roller out of engagement with the winding core, while maintaining engagement between the first applicator roller and the winding core; and (iii) rotating the winding core to cause a length of double-sided adhesive tape to be applied thereto. In use, the double-sided adhesive tape is threaded from the supply to the first applicator roller and thence to the second applicator roller, the free end of the tape lying against the second applicator roller. The movement of the second applicator roller away from the first applicator roller enables the free end of the double-sided adhesive tape to be reliably applied to the winding core. The inner face of the double-sided adhesive tape tends to adhere to the applicator rollers. Indeed, in the start position, the free end of the tape will be adhered to the second applicator roller. Supplies of double-sided adhesive tape generally comprise a non-adhesive interleaving tape which needs to be removed before use. The device for carrying out the method according to the invention may include a take-up spool for this interleaving tape. The double-sided adhesive tape is necessarily of the type which has faces of differential adhesion, the less adhesive face being usually applied to the winding core. This means that when the photographic sheet material is ultimately removed from the winding core, the double-sided adhesive tape remains adhered to the end of the photographic sheet material by being lifted away from the core. The core is therefore in a clean condition, suitable for re-use. We have found that the relative movement of the applicator rollers can be achieved by mounting one of the applicator rollers, preferably the second applicator roller, on a pivoted arm. As the rollers are moved into engagement with the winding core, this arm will pivot and allow the movement of the second applicator roller away from the first applicator roller as required. Ideally, the second applicator roller is biased towards the first applicator roller and this can be achieved by the provision of a spring acting on the pivoted arm. However, we have found that a more reliable operation is achieved if the movement of the pivoted arm in the direction opposite to the bias direction of the spring is restricted. This can be achieved, for example, by the provision of a pawl and catch mechanism associated with the pivoted arm. It is desirable that the double-sided adhesive tape be cut in a predictable manner after application thereof to the winding core. According to a preferred feature of the present invention, a third applicator roller is provided, beyond the second applicator roller and most preferably relatively close thereto. Thus, the third applicator roller is so spaced as to allow the run of double-sided adhesive tape from the supply to the first and second applicator rollers and thence to the third applicator roller. With this arrangement the method of use may now include the further sequential steps of: (iv) moving the first applicator roller away from the winding core to expose a length of tape extending from the first to the second applicator roller, before reaching one revolution of the winding core; (v) ceasing the rotation of the winding core after more than one revolution thereof; (vi) moving the third applicator roller into engagement with the winding core; (vii) cutting the length of the tape extending between the second and third applicator rollers; (viii) further rotating the winding core to cause the trailing cut end of the double-sided adhesive tape to be applied thereto; and (ix) moving the third applicator roller out of engagement with the winding core. Naturally, the length of tape extending between the second and third applicator rollers may be cut by hand, but we prefer that the device includes a knife blade and means for moving the knife blade into and out of a cutting position between the second and third applicator rollers. The tape is held in place, in a tensioned condition, between a guide roller and the second applicator roller. Friction means, such as a spring, acting on the second applicator roller, restrict free rotation thereof and a pawl and ratchet acting on the guide roller prevent the reverse rotation of the guide roller, thereby preventing retraction of the tape after the cutting thereof. The method according to the invention preferably includes the use of a timing device, for example linked mechanically or electronically to the control system of the processing machine, in order to ensure the performance of the method of use in the desired sequence. A tape applicator mechanism comprising two applicator rollers for applying a tape to an object, is disclosed in US-A-3 676 266. This tape application comprises a square rotatable member onto the four sides of which lengths of tape are applied in succession by pulling tape from a supply roll and cutting the tape at corners between adjacent sides. Each time a next length of tape is brought with its centre in contact with a corner of a rectangular article and then the applicator rollers wipe the tape onto the faces of the article as they both become outwardly displaced by their rolling on the tape, supported by the article. This mechanism is unsuited for the application of tape completely around a roll because even in the closed position of the applicator rollers there remains a distance from centre-to-centre of the rollers even which no pressure is exerted on such roll. The present invention is particularly valuable for use with the web processing machine described in more detail in co-pending application numbers and EP 93 20 00 42.5 entitled "Clamping Device". Brief description of the drawings The invention will now be described in further detail with reference to the accompanying drawings in which: Figure 1 shows a front elevation of a dispensing device in a position ready for use; Figure 1A shows a detail of part of Figure 1; Figure 1B shows a removable part of the dispensing device of Figure 1, in the disassembled position; Figure 1C shows the fixed part of the dispensing device of Figure 1, in the the disassembled position; Figure 1C shows the fixed part of the dispensing device of Figure 1, in the disassembled position; Figure 2 is a part view from above of the dispensing device of Figure 1; and Figures 3 to 7 show in diagrammatic form various stages of the use of the dispensing device shown in Figure 1. Detailed description of the invention A first pneumatic cylinder A is mounted in a fixed position and operates on a primary support plate 10 to move the latter in a substantially vertical direction as shown in Figure 1, that is, in a direction towards and away from the axis of rotation of the winding core 50, shown as dotted lines in Figure 1. Mounted on the primary support plate 10 are two secondary support plates 13 and 14, the removable support plate 14 being removable from the non-removable support plate 13. The two support plates can be rotated about an axis 15 relative to the primary support plate by means of a second pneumatic rotating motor B, secured by means not shown to the primary support plate 10. It is the removable support plate 14 which carries the essential components of the dispensing device. Thus, a flanged spool clamp 16 is provided to support a supply 18 of differential adhesion double-sided adhesive tape. A suitable tape is 3M - SCOTCH brand tape No. Y 9415 (Registered Trade Mark). This tape supply comprises a tape 20 of clear polyester material having adhesive coating on both faces and an intermediate non-adhesive interleaving tape 22. The interleaving tape 22 is taken to an interleaving tape take-up spool 24 which is mounted on the removable support plate 14 and driven from a guide roller 26 by a drive belt 25. The double-sided adhesive tape 20 passes over the guide roller 26, which is carried on the removable support plate 14 to a first applicator roller 1, which is also mounted on the removable support plate 14. The guide roller 26 is integral with a pawl disc 55 which is engaged by a leaf spring 53 mounted on the removable support plate 14, which engages the pawl disc 55 and acts as a pawl to prevent retraction of the tape. The arrangement is such that the outer face of the double-sided adhesive tape, as it passes over the first applicator roller 1, is the face which will in use be applied to the winding core 50. The tape is of the type with different adhesion on each side. That side with the highest adhesion lies against the applicator rollers, while that side with the least adhesion is the side which will be applied to the winding core 50. The advantage of using two support plates 13 and 14 is that the supply of double-sided adhesive tape 18 may be placed in position and the tape threaded correctly over the tape path as shown, in the light. The removable support plate 14 of the device may then be affixed to the non-removable support plate 13 by a simple releasable connection as shown in more detail in Figures 1C and 2. Thus the non-removable support plate 13 carries a guide rail 11 which is engaged by a complementarily shaped slider 17 mounted on the removable support plate 14. A manually releasable locking screw 19 serves to hold the removable support plate 14 in position on the non-removable support plate 13. The removable support plate 14 can be affixed to the non-removable support plate 13 in the dark or semi-dark conditions of the processing machine environment. Second and third applicator rollers 2 and 3 respectively are carried at the lower end of a pivoted arm 28 which is pivoted at its upper end to the removable support plate 14, by way of a pivot pin 30. The pivoted arm 28 has a limited degree of freedom of movement, limited by stops E1 and E2 carried on the removable support plate 14. The pivoted arm 28 is urged towards the right-hand stop E1 by a spring 29 mounted between an upstanding edge 31 of the removable support plate 14 and a fixed side arm 35 of the pivoted arm 28, while a pneumatic cylinder C carried on the removable support plate 14 and acting against the fixed side arm 35 is capable of moving the pivoted arm in the opposite direction. The peripheral surface of tape applicator rollers 1, 2 and 3 is such that a reduced adhesion with the tape surface exists. In the present example the rollers have a covering of silicone rubber on a steel core, and the peripheral surface of this covering is provided with a plurality of axially aligned grooves, thereby forming corresponding teeth as shown in cross-section by the crenelated shape of these rollers in Figs. 1, 1A and 1B. It is clear that other surface structures such as wafers may be used for these rollers to limit the adhesion to the inside face of the tape. Carried on the pivoted arm 28, towards the lower end thereof is a side arm 32, pivoted at 33 and spring-loaded by tension spring 34 which extends between the free end of the side arm 32 and a fixed point 36 on the removable support plate 14. Along the length of the side arm 32 is a slot 38 which is engaged by a pawl 40 mounted on the removable support plate 14. The slot 38, while generally longitudinal, has a lateral extension 42, extending in a direction generally opposite to the bias direction of the spring 34 so as to retain the pawl 40 in a position preventing pivoting of the pivoted arm 28, until the side arm 32 is raised against the bias of the spring 34 allowing the pawl 40 to escape into the generally longitudinal portion of the slot 38. Thus, in the disassembled position, the spring 34 causes the side arm 32 to pivot, allowing the pawl 40 to enter the lateral extension 42 of the slot 38, to prevent the pivoting of the arm 28. The raising of the side arm 32 occurs when the removable support plate 14 of the device is affixed to the non-removable support plate 13, by abutment of the arm 32 against a fixed pin 51 mounted on the non-removable support plate 13. It will be seen that when the pawl is engaged in the lateral extension 42, the pivoted arm 28 is at the extreme right-hand limit of its pivotal movement. At the lower end of the pivoted arm 28 is carried the second applicator roller 2. Pivoted to the same axis of rotation as the applicator roller 2 is a relatively short arm 43 carrying at its free end a third applicator roller 3. The short arm 43 is spring-loaded by means not shown in Figure 1, in a downwards direction. As will be seen in Figure 1A, the short arm 43 carries a finger 45, from the free end of which a spring 48 extends to the end of an adjustable bolt 49, secured to the pivoted arm 28 by the aid of a nut 47. Bearing against the surface of the second applicator roller 2 is a friction plate 46 secured to the side edge of the pivoted arm 28, so as to restrain the free rotation of the second applicator roller 2. Thus, the three applicator rollers 1, 2 and 3 are arranged with their axes of rotation parallel, but with the possibility of limited relative displacement by operation of the pneumatic devices A, B and C. In particular, any one of the three applicator rollers can be moved into engagement with the winding core, by operation of the pneumatic devices A and B, and the second applicator roller 2 can be moved laterally away from the first applicator roller 1 by causing the pivoted arm 28 to be pivoted to the left as seen in Figure 1 by operation of the pneumatic cylinder C. The apparatus works as follows. As a first step, in order to supply the unit with the tape dispensing device, the pivoted side arm 32 is lifted by the pin 51 when mounting the removable support plate 14 in a downwards direction as seen in Figure 1 onto the non-removable support plate 13 and securing the locking screw 19. This causes the pawl 40 to leave the lateral extension 42 of the slot 38 enabling movement of the pawl in the longitudinal portion thereof. As shown in Figure 3, the first and second applicator rollers 1 and 2 are moved into engagement with the winding core 50. The free end 52 of the double-sided adhesive tape 20, lies against the second applicator roller 2. Although not shown in Figure 1, there is attached to the primary support plate 10, at the lower end thereof, a knife-operating mechanism which comprises a knife blade 44 (see Figures 6 and 7) carried on an arm which is operated by a pneumatic cylinder 41, the arrangement being such that the knife may be extended into the tape cutting position shown in Figures 6 and 7 while at other times in the operating sequence it may be retracted out of the way to a rest position. As shown in Figure 4, as the cylinder A pushes the dispenser further in the direction of the core 50, pivotal movement of the pivoted arm 28 to the left causes the second applicator roller 2 to move laterally away from the first applicator roller 1, while maintaining engagement with the winding core 50, thereby to apply the free end of the double-sided adhesive tape 20 thereto. At this point, further tape 20 begins to be fed from the spool 18. By operation of the pneumatic cylinder C, the pivoted arm 28 moves to the left against the stop E2. This causes the second applicator roller 2 to move out of engagement with the winding core 50, as shown in Figure 5, while maintaining engagement between the first applicator roller 1 and the winding core 50. Thereafter, the winding core 50 is rotated by a predetermined angle in the direction of the curved arrow in Figure 5 to cause a length of double-sided adhesive tape 20 to be applied to the winding core. At the same time the pneumatic cylinder B is activated to rotate the dispenser about the axis 15 thereby to prepare this device for entry between the rollers 2 and 3 in a later phase. The applicator roller 1 is released from the core by this movement. Where it is desired to apply tape round the whole circumference of the core, it is suitable to rotate the core by 1.2 rotations. Cylinder C is now retracted and the spring 29 causes the applicator roller 3 to engage with the winding core 50 (See Figure 6), to hold the double-sided adhesive tape 20 against the winding core. The pressure applied by the third applicator roller 3 includes spring pressure from the tension spring 48 (see Figure 1). The applicator roller 2 is released from the core by this movement, with tape still adhered thereto. It also causes the pivoted arm 28 to pivot to the right under bias of the spring 29 against the stop E1, to expose a length 54 of tape extending from the second applicator roller 2 to the third applicator roller 3. At this stage, the tape 20 still contacts the applicator roller 2 at a slight looping angle. The knife-operating mechanism 41 is now activated to cause the knife blade 44 to move into the cutting position as shown in Figure 7 to cut the length 54 of tape extending between the second applicator roller 2 and the third applicator roller 3. As shown in Figure 7, the winding core 50 is then rotated, over a short angle, to cause the trailing cut end 56 of the double-sided adhesive tape 20 to be applied thereto, pressed into place by the applicator roller 3, while leaving a freshly cut free end 52, curls and becomes adhered to the second applicator roller 2. Now that the pivoted arm 28 has returned to the right, against the stop E1, the pawl on the guide roller 26 prevents any return movement of this roller. This "pawl" system prevents the tape from being drawn back into the dispenser, which by virtue of the elasticity of the tap may otherwise occur. The friction plate 46 acting on the second applicator roller 2 prevents this roller from rotating, thereby to retain a residual stress in the tape between applicator rollers 2 and 3. Finally, the cylinder A retracts to raise the dispenser, moving the third applicator roller 3 out of engagement with the winding core 50, the cylinder B rotates the dispenser back about the axis 15 and the knife 44 is returned to its rest position to be ready for a fresh winding core to be put in place. The reliability of operation of the device according to the invention is high. However, in view of the vital importance of the adherance of the fresh end of a web to an empty winding core, the correct application of a tape to the winding core yet was manually examined for each new web. We have found that the reliability of the device is a disadvantage in this respect since the attention of the operator releases after thousands of perfect tape applications. If then an operation of the tape dispenser does not produce a correct tape-winding on the core, this may pass unnoticed having for consequence an interruption of the production process. It may therefore be desirable to provide detection means signalling the correct application of a tape. Common infrared or capacitive sensors can be used to this end.

Claims: Method for applying adhesive tape to the winding core of a web processing machine by means of a device comprising : support means (10, 13, 14) for a first and second tape applicator roller (1, 2) and a roll (18) of adhesive tape (20), the support means being so arranged to allow a run of adhesive tape from the roll to the first applicator roller (1) and thence to the second applicator roller (2); means (A) for moving both applicator rollers into and out of engagement with the winding core (50); and means (28) for moving the second applicator roller (2) relative to the first applicator roller (1); which method comprises moving the first and second applicator rollers (1, 2) into engagement with the winding core (50), and moving the second applicator roller (2) away from the first applicator roller (1) while maintaining engagement with the winding core (50), thereby to apply the free end (52) of the adhesive tape thereto; characterised by the following steps : (i) using differential adhesion double-sided adhesive tape, (ii) moving the second applicator roller (2) out of engagement with the winding core (50), while maintaining engagement between the first applicator roller (1) and the winding core (50); and (iii) rotating the winding core (50) to cause a length of double-sided adhesive tape (20) to be applied thereto. Method according to claim 1, comprising rotating the winding core over at least 1.2 rotations to apply the tape thereto. Method according to claim 1 or 2, wherein the device further comprises a third applicator roller (3) so spaced as to allow a run of adhesive tape from roll (18) to the first and second applicator rollers (1, 2) and hence to the third applicator roller (3), wherein the method includes the further sequential steps of : (iv) moving the first applicator roller (1) away from the winding core (50) to expose a length of tape extending from the first (1) to the second applicator roller (2) before reaching one revolution of the winding core (50), (v) ceasing the rotation of the winding core after more than one revolution thereof, (vi) moving the third applicator roller (3) into engagement with the winding core; (vii) cutting the length of the tape extending between the second and third applicator rollers (2, 3); (viii) further rotating the winding core (50) to cause the trailing cut end (56) of the double-sided adhesive tape (20) to be applied thereto; and (ix) moving the third applicator roller (3) out of engagement with the winding core (50). Method according to claim 3, wherein the device further comprises a knife blade (44) and means (41) for moving the knife blade (44) into and out of a cutting position between the second and third roller (2, 3), wherein step (vii) of the method comprises moving the knife (44) into the cutting position to cut the length of tape extending between the second and third applicator rollers (2, 3). A method according to any of claims 1 to 4, comprising applying the less adhesive face of the differential adhesion double-sided adhesive tape to the winding core (50).

Inventors: DE ROECK JOZEF, DE ROECK, JOZEF, DE ROECK, JOZEF, C/O AGFA-GEVAERT N.V., DIE 3800
Applicants: AGFA GEVAERT NV, AGFA-GEVAERT NAAMLOZE VENNOOTSCHAP
Application year: 1993
Main classification: B65H19
IPC codes: C09J5, B65H19, B65H35