WINDING STRIP MATERIAL

Abstract: A method of and apparatus for winding strip material onto a drum (27A, 28A) from a supply of the material in which a "slack length" (3A) is produced in the strip material (3) at a predetermined location between the drum and the supply. The "slack length" is produced by allowing the strip material to droop catenary fashion between two rollers (13, 15) spaced apart in the feed path. The edge region or edge of the strip ma­ terial in the "slack length" is arranged to contact and move ac­ ross an inclined surface. The winding conditions onto the drum are such that the lowermost part of the catenary is maintained between upper and lower levels (21, 22), the position of the lowermost part being continuously monitored.

Description: WINDING STRIP MATERIAL. FIELD OF THE INVENTION This invention relates to methods of and apparatus for controlling the winding of strip material from a supply thereof onto an arbour, drum, former, reel or the like. BACKGROUND OF THE INVENTION During the winding of strip material onto a drum or the like in order to achieve a wind of the desired tightness and quantity it is necessary to control the tension that is exerted upon the materiol being wound during the winding operation. In particular, it is usually desirable that after winding the turns of the wound material are not able to move easily relative to each other. In addition, it has been found that materials such as plastics materials are able readily to stretch and deform during winding of the material as it is being extruded from an extruder for the strip. In addition,it has also been found that if such materials are stretched or otherwise deformed or distorted during the winding process the stretching or distortion is permanent so that in many cases the material cannot be used. A further consequence of stretching is that the amount of strip material laid onto the drum or the like is a highly variable quantity. As a practical consequence of the possibility of under-tensioning or over-tensioning arising during the winding operation it has been found necessary to carry out the winding operation at a slower rate than it would otherwise be effected so that the overall efficiency and thus productivity is restricted. SUMMARIES OF THE INVENTION Broadly, according to the invention there is provided a method of controlling the winding of strip material onto an arbour, drum, former, reel or the like comprising the steps of passing the material being wound through a tension tension control buffer unit before passing the material to a winding machine performing the winding of the strip material to establish in the buffer unit a 'slack length' in the strip material between predetermined locations in the feed path of the material to the winding machine, and positionally guiding the 'slack length' by quide arrangements co-operating with the 'slack length'. Preferably, the guiding of the'slack length' involves guiding an edge or edge region of the strip material. Conveniently, during the winding operation the edge or edge region is caused to move along a support surface whose plane is inclined to the vertical whereby substantially the whole of the edge or edge region of the 'slack length' is supported. Preferably, the inclination of said surface is selectively adjustable. According to a second aspect of the invention there is provided apparatus for controlling the winding of strip material from a supply thereof to a material winding station, the apparatus including means for establishing a 'slack length' in the material whilst in a feed path from the supply to the winding station, and means for guiding the material at least in the region of the 'slack length'. Preferably, the apparatus includes control means responsive to the length of material located in said 'slack length' for controlling the rate of feed of the strip material forming the 'slack length' to be within predetermined limits. Preferably, the 'slack length' is provided within a chamber having a strip material input and a strip material output which are spaced apart a predetermined distance in said feed path sufficiently to provide therebetween a reservoir for accommodating the 'slack length'. Preferably the guide means includes a guide plate or other surface for positionally locating the 'slack length' with respect to the chamber. In addition, means are provided for detecting when the amount of material contained in the 'slack length' departs from a predetermined amount and for producing a related output control signal which is utilisable for the control of the winding operation. Conveniently, the control signal is utilised to control the rate of winding the material onto the drum, reel or the like. Conveneiently, the 'slack length' is formed by allowing a length of the strip material to droop into the chamber catenary fashion. Preferably, the means responsive to the presence of the ' slack length' is arranged to detect when the lowermost part of the 'slack length' moves above or below upper or lower levels in the chamber. #¯ particular form of the detection means includes photoelectric detection means. In a preferred construction of the chamber of the apparatus one of the side walls of the chamber is utilised to provide a reference surface which serves to guide the edge or edge region of the strip material whilst forming the 'slack length. BRIEF DESCRIPTION OF THE DRA#;INGS For a better mderstanding of the invention and to show how to carry the same into effect reference will now be made to the accompanying drawings in which Figure 1 is a schematic side view representation of a strip material winding installation including a strip material winding machine and a buffer unit interposed between the machine and a supply of strip material (not shown); Figure 2 is a plan view of the installation of Figure 1; Figure 3 is a sectional view of the buffer unit of Figures 1 and 2; Figure 4 is a schematic perspective view of the winding machine of Figures 1 and 2; Figure 5 is a block diagram of an electrical control circuit for inter-relating the operation of the winding machine and the passage of strip material through the buffer unit; and Figure 6 is an exploded view of a mandrel arrangement affording adjustable mounting for a drum or the like for receiving the wound strip material. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and more particularly to Figures 1,2 and 3 which show a winding machine 1, and a buffer unit 2 which is positioned in the feed path between a supply of the strip material 3, the supply not being shown, and the winding machine 1. For convenience of description the details of the construction of the buffer unit 2 will be considered initially, after which the details of the winding machine will be considered. Following this the inter-relation of the machine 1 and the buffer unit 2 in order to achieve the desired winding of the strip material 3. As shown in the Figures 1 to 3 the buffer unit 2 includes a framework including a base 4 and support means or uprights 5,6 to which is secured or is supported by a back plate 7. As will be particularly seen, in particular Figure 3, the uprights 5,6 are so mounted from the base 4 that the plate 7 is inclinded to the vertical. The inclination is at a required angle. 0 For example, the inclination can range between 1 to 30 With a particular range being between 50 to 150. It will be appreciated that if it is desired arrangements may be made to allow for adjustability of the inclination of the back plate 7. For convenience, Figure 3 shows an arrangement for enabling the adjustment of the inclination. As shown the arrangement includes pivoting the uprights 5,6 to the frame 4 by pivots schematically shown at 8. A link or the like 9 is pivoted at one end thereof 9A to the base 4, therebeing one such link for each support 5,6,. A lengthwise slot 10 is formed in each link and the link is secured to the uprights by means of a retaining bolt or screw 11 engaging the slot and the uprights. If desired,the adjustability can be achieved by arranging for the back plate to be pivotally mounted and the links or the like co-operating with the pivoted plate 7. If desired, the buffer unit may be formed into a chamber 2A by mounting a front plate 12 or wall to the uprights 5,6. Conveniently, the front wall 12 would be transparent. Also, if desired, the back plate may be transparent so that the situation relating to the material passing therethrough may be readily noted. Preferably, means (not shown) are provided for enabling selective adjustment of the separation between the back plate 7 and the front plate 12 so that the chamber 2A can accommodate varying widths of the strip material. Conveniently, the width adjustment means can comprise spacers or the like which are engageable with bolts provided for mounting the back plate 7 and the front plate 12 to the uprights 5,6. A strip material feed roller 13 is provided upon a support 14 located near the end wall or upright 5 and a second material feed roller 15 is provided on a support 16 located near the end wall or upright 6. In addition, a sensing means 17 is provided in the vicinity of the feed roller 15 for measuring the length of strip material which has been fed past the roller 13. The axes of rotation of the rollers 13,15 are perpendicular to the plane of the back plate 7. Thus if if the plate is positionally fixed to the uprights the rollers can conveniently be mounted from the uprights. If the plate is pivotally mounted the rollers can be mounted from the plate 7. As can be seen from Figures 1 and 2 the width of the chamber 2A is relatively narrow as compared with its length and depth. In practice, the internal width of the chamber 2A needs only to be slightly greater than that of the strip material 3 being fed so that whilst a strip of material being fed can easily pass from the feed roller 13 to the output roller 15 with a length 3A providing the'slack length' by drooping into the chamber 2A catenary fashion. The width of the chamber is selected such that the width is not sufficient for the 'slack length' easily to tangle or otherwise jam in the chamber 2A. Because of the inclination of the back plate 7, and as the feed rollers 13 and 15 have their axes of rotation perpendicular. to the plane of the back plate 7 whatever the inclination angle of the latter to the vertical direction a bias is introduced, during the feed of the material, into the 'slack length' so that it tends to fall, i.e., lie,towards and thus abut the inside surface 18 of the plate 7. The contact is along the edge or edge region 19 of the strip length 3A. That is to say during the travel of the strip material 3 through the chamber 2A the portion 3A thereof at any time forming the 'slack length' runs against the surface 18 of the plate 7. Thus the surface 18 defines for the adjacent edge 19 of the strip 3 a guide surface or reference plane during its movement through the chamber. Extensive investigations have shown that the fact that the edge 19 runs against the surface 18 does not lead to any adverse increase in the winding tensions that may be produced in the strip material during winding. In fact it is believed, as a result of winding very easily stretchable materials , that the use of the apparatus of the invention does not introduce any tension other than that necessary to obtain a correct lay on a drum. In the circumstances it has been found that the winding process does not damage the material whether it is symmetrically or unsymmetrically profiled material that is being wound. In addition, it has been established that the running contact between the edge 19 and the surface 18 has greatly reduced the possibility of tangling or jamming of the strip 3 whilst in the chamber 2A even when winding relatively warm plastics strip which is very highly susceptible to stretching and twisting during handling in the warm condition. These warm winding conditions are a very common factor involved in the winding of plastics material as it is produced at the output of a plastics extrusion machine. It is believed that the provision of the guide surface inclined to the vertical provides a steadying influence to the orientation of the material in the chamber throughout its complete passage through the chamber thereby offsetting the induction of twist which usually leads to tangling of the strip. A photoelectric detection system 20 is provided for determining the position of the 'slack length' with respect to predetermined upper and lower 'levels 21 and 22 relative to the depth of the chamber 2A. The detection system 20 includes at the upper level a photoelectric detector 23 and an associated emitter 24 suitably aligned therewith. The system also includes at the lower level a detector 25 and an associated suitably aligned emitter 26. Each photoelectric detector unit 23,25 is arranged to produce a control signal which is applied to a control unit (not shown in Figures 1 and 2) associated with the winding machine 1. In practice, the difference in the rate of strip material feed into the buffer unit chamber 2A and the delivery therefrom is such that the 'slack length' 3A interrupts the light path between the emitter 24 and the detector 23 at the upper level 21 and such that it does not interrupt the light path between the corresponding units 25 and 26 at the lower level 22. That is to say the detector 23 at the upper level can be regarded as being normally OFF and the detector 25 at the lower level 22 can be regarded as being normally ON. In use, if the difference between the feed of the strip 3 to the chamber 2A and the delivery therefrom is such that more than the predetermined amount remains in the chamber during the winding operation the amount of 'slack length' 3A increases and when its length is such that it has effectively lowered sufficiently to pass through the above defined lower level 22 the light path between the detector 25 and the emitter will be broken whereby the detector 25 will be effectively switched off thereby changing the electric signal delivered to the control unit. In practice, this signal change is a cut-off signal which is arranged to speed up the rate of the winding of the material onto a drum or the like, or if it is more convenient to slow down the rate of discharge of the material from the supply, i.e., the delivery rate to the chamber 2A. If on the other hand the feed of the material from the chamber 2A starts to exceed the rate at which it is delivered to the chamber 2A it will be clear that the length of the strip material forming the 'slack length' will be reduced and, in consequence, the lowermost part of the 'slack length' catenary will move upwards within the chamber 2A and if the in-balance of the strip material continues a point will be reached in which the lowermost level of the 'slack length' will move above the upper level 21. At this point of time the 'slack length' 3A will cease to interupt the light path between the emitter 24 and the detector 23 whereby the detector 23 is effectively switched ON and will thus produce an output signalwhich is applied to the above mentioned control unit. As has been mentioned the output signal can be utilised either to reduce the rate of winding onto a drum or to increase the rate of material supply to the chamber, according to whichever adjustment is considered to be the most convenient. A winding unit for receiving the strip material after it has passed through the chamber 2A will now be briefly considered in relation to Figure 4. It should be noted that the winding unit of the Figure is schematically represented and that,in practice, the relative positioning of the components may differ from that shown in the Figure 4. Thus the Figure 4 may be regarded as illustrating the principal features of a winding machine. The winding machine includes an upper shaft 27 adapted for mounting a bobbin, drum, former, spool, reel or the like 27A (not shown in Figure 4) onto which the strip material 3 is to be wound, and-a.Iower shaft 28 adapted to mount a bobbin,drum, former, spool reel or the like and located effectively beneath the shaft 27. The shaft 27 extends outwardly from the side of a housing unit 29 which is mounted upon a support frame or pedestal 30* The shaft 28 is carried from bearing arrangements 31 Similarly, the shaft 27 is mounted from suitable bearing assemblies 32 provided within the housing unit 29. The shafts 27 and 28 are connected to receive drive from the output shaft 33 of an electric motor 34 by way of a belt drive system 35. This drive system includes a layshaft unit 36 mounted from bearings 37 The layshaft unit 36 is provided with a pulley wheel 38 which mounts a drive belt 39 connecting with a pulley wheel 40 on the shaft 27. The layshaft unit is provided with a pulley wheel 41A which mounts a drive belt connecting with a pulley wheel 43 on the lower shaft 28. A clutch arrangement 41.,42 is provided on the layshaft unit 36 whereby drive from the shaft unit may be selectively fed from the drive motor to the upper or the lower shafts 27,28. In practice, the clutch arrangement 41 provides a tube 36A journalled on the shaft unit 36 which carries the pulley 41 and which can be selectively coupled to receive drive from the shaft 36 or to allow the shaft 36 to run freely within the tube. As shown the drive system 35 includes a pulley 35A on the shaft 36 and a belt 358 receiving drive from the motor output shaft 33. The clutch arrangement 42 is of a generally similar construction. It will be observed that the use of the concentric tube arrangements in the clutch constructions the shaft 36 effectively provides an extended length bearing support for the adjacent ends of the tubes 36A. It will be understood that other forms of clutch could be used. Upper and lower strip material feed and guide rollers 43A and 43B are provided for guiding the strip material during the winding operation in such manner that the material is laid onto the drum or the like in regularly spaced side by side arrangement and in layers. These rollers 43A and 438 are mounted from a traversing mechanism 44 which is supported from the housing unit 29. The mechanism includes a traversing block having arms 46A and 468 which respectively mount the rollers 43A and 438. The block 45 is moveable lengthwise of a traversing shaft 47 connected to receive drive from the motor 34 by way of a belt drive 48 including pulley wheels 49 and 50, and belt 51. The traversing mechanism 44 incorporates means (not shown) whereby the movement of the block 45 changes, that is reverses, direction each time it completes a traversing movement of a desired amount. The electomagnetic clutches 41,42 enable disengagement of the drive for various operational purposes such as , for example, when a drum or the like is being changed after the desired amount of strip material has been wound onto the drum and is being replaced by an empty drum. In addition, the provision of the clutches 41,42 allows the changeover of the winding operation from drum to drum i.e., from a drum on one shaft to a drum on the other shaft with out it being necessary to stop the winding operation. In situations where the rate of material feed is high the fast changeover between drums is very important so as to avoid excessive waste of material. In order to facilitate the changeover of the drums to and from the shafts 27 and 28 each shaft 27,28 is provided with a spring loaded mandrel 60 which essentially includes four radially directed blocks 61,62,63 and 64 equiangularly spaced around the associated shaft 27 or 28. The blocks are held in place by countersunk bolts 65 and are resiliently loaded by compression springs 66. If it is desired to expand the overall width of the mandrel a second set of the blocks i.e., blocks 61A,62A,63A and 64A can be mounted to the blocks 61-64 by using longer bolts 65. It will be understood that the buffer unit 2 and the windine machine 1 need to be electrically interconnected. In the drawings this connection is very schematically shown by the cable and fittings 66. When the apparatus is in use the strip material is engaged with the rollers13 and 15 and also by way of the roller 43A or 438 of the traversing mechanism 44 and thence to a drum 27A or 28A according to which of the drums is to be used. The requisite 'slack length' is formed in the chamber 2 and the end of the strip 3 is engaged with the requisite drum. The motor 34 is started. It is of course assumed that material is available from the supply. Provided that the various conditions mentioned above arise the 'slack length' will droop into the chamber 2A to a position in which the lowermost part thereof is above the lower level 22. The position of the lowermost part of the 'slack length' is monitored by the photoelectric detection system 20 which will be producing a first control output. In addition, the length detector 17 will be measuring the amount of strip material fed through the chamber 2A and will be producing a second control signal output. At the same time the traversing mechanism 44 will be laying the strip material onto the drum in successive layers. It will be understood that at any time only one drum 27A or 28A will be receiving strip material. During the winding operation there will be a progressive change in the rate of feed of the strip material from the chamber 2A as a result of the progressive increase in the effective diameter of the drum as more and more material is laid onto the drum in successive layers. This progressive feed rate increase is accommodated during winding by the shortening of the 'slack length' as is shown in Figure 1 in which the full line shows the starting droop shape of the 'slack length' and the dashed line 3A shows the droop shape of the 'slack length' during a later stage of the winding operation. It will be understood that as the diameter on the reel or drum continues to increase the diameter can be monitored by sensing means and the feed rate adjusted to take into account the diametrical change. Alternatively, the feed rate can be modified according to the overall length of strip material fed through the chamber 2A. As has been mentioned.dbove during its passage through the chamber 2A the 'slack length' bears against the inclined back plate 7 and in particular against the surface 18. This contact is restricted to a contact between the edge or edge region of the strip material and it has been found that this co-operation acts in such manner as not only to prevent any twisting or distortion of the strip material but also to considerably reduce tension in the material being wound. These results have been found to be maintained when winding a wide variety of strip material cross sections and profiles and through out a wide range of sizes from,for example,one millimetre diameter to several hundred millimetres in width. A further important factor arising from the contact effected between the surface 18 and the strip material edge is that the 'slack length' is not able to move sufficienly out of its intended path to lie outside the optical paths and thus give rise to spurious signals which could lead to unrequired adjustments to the winding and/or feed rates. It should be noted that the above mentioned factors relate to the winding of a drum on either shaft so that if necessary a single shaft arrangement could be constructed. Figure 6 schematically shows in block diagram form the broad details of electric and electronic arrangements for enabling the control of the motor drive to the shafts 27 and 28 in response to the outputs from the photoelectric detection system 20. As will be seen the output from the detection system feeds into an electronic decoding logic unit 51 which serves to identify which of the photoelectric detectors 23 and 25 has been caused to vary its output in consequence of movements of the lowermost part of the 'slack length' 3A relative to the upper and lower levels 21 and 22. The decoding unit 51 produces an output signal which is fed tothe motor control unit 52 which has an output which controls the actual operation of the motor 34. The length sensor 17 produces an output which is representative of the instantaneous amount of strip material 3 that has been fed through the chamber 2A. A strip length required signal, which is selectively established in a length amount presetting unit 53 produces an output signal characteristic of the amount of strip material that is to be wound onto a drum. This latter signal is compared with the instantaneous length signal in a comparator 54 which is effectively a counter type comparator. This comparator unit 54 produces a control signal which is applied to the motor control to cause the latter to stop drive to the shaft 27 ov 28 by operation of the clutches as required. A motor drive accelerator control 55 is provided for over-riding the control exerted by the photoelectric detection system 20, this control providing the facility that an operator of the winding installation can wind in any excess material that may accumulate during the time period required to replace a full drum or the like with a fresh drum or the like. This particular time period is in fact considerably reduced in practice by the provision of the upper and lower winding shafts 27 and 28 since the shaft for the time being not actually winding can be pre-fitted with an empty drum of the like thereby reducing changeover time to that required to cut the strip and join the strip end to the new drum on the other shaft.

Claims: CLAIMS 1. A method of controlling the winding of strip material onto an arbour, drum, former, reel or the like (27A,28A), characterised by the steps of forming a 'slack length' (3A) in the strip material (3) at a predetermined location in its feed path between a supply thereof and the drum or the like (27A,28A) whilst the material is being wound onto the drum or the like, and physically guiding the strip material whilst it is in the 'slack length'. 2. A method as claimed in claim 1, and further characterised in that the 'slack length' (3A) is guided by an edge or edge region (19) co-operating with a guide means (7) presenting a working surface (18) which is inclined to the vertical. 3. A method as claimed in claim 1 or 2, and characterised in that the strip material is guided to drum or the like (27A, 28A) by way of spaced apart guides and feed means (13,15) so located with respect to the 'slack length' location and guide means (7) that the 'slack length' (3A) is formed by allowing the strip material to droop catenary like between the guide and feed means (13,15), and in that the winding of the strip material (3) onto the drum or the like (27A, 28A) is controlled by maintaining the 'slack Length catenary between two levels ( 21,22 ) arranged one above the bother by adjusting the rate of strip material supply, by varying the rate of winding onto a drum or the like (27A,28A) or by a combination of both supply adjustment and rate of winding. 4. A method as claimed in claim 1,2 or 3, and characterised in that the conditions of winding are varied so as automatically to compensate for the increase in the diameter of the wound material on the drum or the like (27A,28A) during the winding of the material onto the drum. Apparatus for controlling the winding of strip material (3) from a supply thereof onto an arbour, drum, former, reel or the like (27A,28A), the apparatus being characterised by a winding machine (1) for imparting rotation to the drum or the like, means (2) for establishing a 'slack length' (3A) in the strip material (3) whilst in a feed path from the supply to the drum or the like, and means (7) for guiding at least that strip material which forms the 'slack length'. 6. Apparatus as claimed in claim 5 and characterised in that the guide means (7) includes means (18) for presenting a guide surface (18) to an adjacent edge or edge region (19) of the strip material whilst it is in the 'slack length' tA) 7. Apparatus as claimed in claim 5 or 6, and characterised in that the 'slack length' guide means (7) includes a plate or other surface (18) which is inclined to the vertical in a fixed or selectively adjustable manner, whereby the weight of the strip material (3) forming the 'slack length' serves to maintain guiding contact between the edge or edge region (19) andthe surface (18). 8. Apparatus as claimed in claim 5,6 or 7, and characterised by means for varying the winding conditions so as automatically to compensate for the increase in the diamater of the wound material on the drum or the like (27A, 28A) during the winding of the strip material. 9. Apparatus as claimed in any one of claims 5 to 8, and characterised by means (23,24,25,26) for monitoring the !.Level of the lowermost part of the 'slack length' with respect to two levels (21,22) located one above the other, and for producing an output signal characteristic of displacement of the lowermost part below the lower level or to a position above the upper level (21) and in that means (51,52) are provided for enabling variation of the winding conditions of the strip material with a view to maintaining the lowermost part of the 'slack length' between said upper level (21) and the lower level (22). 10. Apparatus as claimed in claim 9, and characterised in that the monitoring means includes photelectric emitter (24) and detector (23) combination at the upper level (21) and an emitter (26) and detector (25) combination at the lower level (22), the arrangement being such that for acceptable winding conditions the lourmost part interupts the light path between the emitter (24) and detector (23) and allows a light path between the emitter (26) and the detector (25), and in that if the 'slack length increases in size sufficently for the lowermost part to interupt the combination (25,26) at the lower level the winding conditions are changed to remove the interuption, and in that in the event that the 'slack length' decreases in size to the extent that the lowermost part lifts above the upper level (21) the interuption of the combination (23,24) at the upper level (21) is removed and the winding conditions are changed to bring the lowermost part below the upper level (21)

Inventors: BOOTAN, ALAN JOHN
Applicants: BOOTAN, ALAN JOHN
Application year: 1982
Main classification: B65H20
IPC codes: B65H20