A winding apparatus for sheet material web

Abstract: A winding spindle (37) is mounted on a spindle-holder lever (26), carried on a horizontally traversable carriage (16). The spindle cooperates with a calender (42) for winding a roll (B) of sheet material web (N) on the said spindle. A control device (32; 66) and a related control system control the position of the carriage, and therefore of the spindle, with respect to the calender, as the thickness of the roll increases. The apparatus can work as a surface winding winder or as a combined cetre-surface winding winder.

Description: The invention refers to the field of handling a continuos web of sheet material, for example of plastic material, such as polymer, or paper. Downstream of the devices for the production of such sheet material, the latter must be wound into rolls for easy handling and transport. Each roll is usually wound onto a core carried by a spindle or mandrel; often the spindle cooperates with a winding cylinder or calender having its axis parallel to the axis of the spindle. This cylinder ensures a certain pressure on the roll being formed, to ensure the evenness of the winding. The apparatuses already known for winding rolls, comprising a spindle and possibly a calender, are usually divided into three groups called centre winding winders, surface winding winders and combined centre-surface winding winders. In the centre winding winders the spindle or central shaft of the roll is motor-driven. In the surface winding winders the calender is motor-driven, and the spindle is idle and is rotated by contact of the calender with the winding which is being formed on it. The combined winding winders are a combination of the previous winder systems, that is the draft on the web is a result of the combination of central draft and of dragging by surface contact. From this type of winder a further system is derived, which consists of winding through a central draft at a preset distance between the outside of the roll and the surface of the calender. Usually the two last systems exist together on the same machine. In order to be able to realize surface winding, it is obviously necessary to apply pressure between the shaft of the roll and the contact cylinder. This can be obtained by using the weight component of the devices of the machine, and the most common solution is to mount the spindle on pivoted arms and make use of the weight of the roll itself. One problem with these systems, however, is that the contact pressure between the roll and the calender (or in other words the "rolling force", meaning the force with which the roll presses on the calender) increases with the increase in the diameter of the roll, while it would be preferable for it to remain constant to achieve good winding with constant characteristics on all the thickness of the roll. Various ways have been tried to make the rolling force constant. In a known winder the weight component of the roll is set at zero due to the fact that the axle of the spindle is supported on a horizontal plane, and a determined load is applied to the roll towards the calender. However it is difficult to control this load. In addition this system cannot be transformed into a centre-surface winding system because of the difficulty of motorizing the spindle axle. Another known winder (EP-A-0 017 277) of the surface winding type mounts the spindle on a lever, oscillating between a position against the calender and an unloading position. The rolling force is realized by making use of the weight of the roll, and a load cell is positioned on the calender and regulates the angle of the spindle-holder lever according to the detected load. In this case however the angle of incidence of the weight of the roll with respect to the cylinder is variable and this variation is neglected. DE-A-2 632 608 (Nishimura Seisakusho Co, Ltd.) discloses a winding apparatus for winding a web of sheet material comprising: a winding calender, at least one spindle-holder or roll-holder lever, for supporting a spindle, for winding a roll of web, the axis of the spindle being parallel to the axis of the calender; a carriage onto which the said spindle-holder levers are mounted for a horizontal traverse movement, a detector element for detecting the winding, a movement means for the carriage, and a control system for determining the traverse of the said carriage according to the increasing winding on the spindle. Said spindle-holder levers are pivotable on the said carriage and are movable between an upright working or web winding position for forming a roll, in which position the axes of the spindle is coplanar on a horizontal plane with the axis of the calender and lie on a same vertical plane with the pivots of the spindle-holder lever, and a lowered position for unloading the roll. The disclosed detector element is a spindle-holder levers position sensor (in its turn, the position depends upon the winding sizes). However this inevitably causes a stick-slip-motion of the carriage, that has repercussions, through the time, on an irregular motion of the rolling force or pressure, which could be acceptable for some applications, but it is not for others, e.g. in applications where a thin plastic film is wound just dowstream the production, where a rolling pressure irregularity inevitably leads to form wrinklings, and therefore, a low quality product. Furthermore Nishimura apparatus does not allow to replace the roll during the apparatus working phase (it is shown in a web slitting machine, that usually operates in a discontinuous way); moreover Nishimura does not explain how beam 34 is rotated about axis 40. GB-A-1007983 discloses a lever control system having a couple of levers pivotally mounted on a carriage along an axis parallel to the pivoting axis of the spindle-holder levers, and a driving lever or a couple of driving levers pivotally mounted along an axis parallel to the pivoting axis of a couple of levers. Neither any teaching is given, throughout the description, on how could such a structure be combined with load cell detector, nor is it self-evident; also, the problem of the continuous movement of the continuous regulations of the rolling load has not been posed. Also in this case no possibility is foreseen of replacing a completed roll in a continuous production process. DE-A-3 627 463 discloses a winding apparatus whose winding roll is in a still position and the calender is mounted on a movable carriage; a load cell detects the load on the calender. However said solution cannot be applied to continuos winding machines; in the roll replacement stage the calender must be moved away from the roll, so as to remove the roll. Therefore, as regards the wound final portion of the web as well as for the time required to the replacement stage, there is no contact control and thus the last turns of the wound web must be scrapped. Finally, DE-A-2 741 083, discloses an apparatus having a movable calender and a fixed roll, as the one disclosed in DE-A- 3 627 463 (and therefore that cannot be applied to continuous windings) in which the movement of the calender is determined by a photoelectric cell that detects an air gap between the roll and the calender. The aim of this invention is to avoid the drawbacks in the prior art and to allow precise and constant control of the rolling load between the roll and the calender. A further aim is to realize a surface winding type winder, which can easily be adapted to work with combined draft winding. A further aim is to realize a device which allows the roll to be ejected automatically. The aims described above have been achieved with an apparatus according to claim 1. The new winding apparatus allows perfect control of the contact force between the roll and the calender, that is to say of the rolling load, independently of the conditions of the weight of the roll; it allows the automatic ejection of the roll; it can be realized both in a form suitable for surface winding operation, or in a form suitable for combined winding operation. An embodiment preferred at present is described below merely as an example and not restrictive, with reference to the appended drawings, in which: Figure 1 is a diagrammatic vertical longitudinal sectional view along 1-1 in figure 7 along an apparatus in a surface winding condition or in a combined winding condition, with the roll in contact with calender, and illustrated at the beginning of winding; Figure 2 is a sectional view similar to figure 1, which illustrates the end of winding condition (maximum diameter); Figure 3 is a vertical longitudinal sectional view of the apparatus in a roll unloading condition; Figure 4 is a sectional view along 4-4 in figure 1, illustrating the mounted load cell; Figure 5 is a longitudinal sectional view similar to the previous ones, showing the apparatus working in a combined or centre-surface winding condition, with a preset distance between the roll and the calender; Figure 6 is a front view, from the left of figure 5; Figure 7 is a plan view from the top of figure 6; Figure 8 is a diagram of the control circuit for operation with controlled rolling load; Figure 9 is a diagram of the control circuit for operation with preset distance between the roll and the calender. The apparatus is shown as a whole with reference number 10. It comprises a fixed framework 12, comprising a pair of vertical shoulders 13, each having a base 14. Horizontal longitudinal parallel guides are supported on both the shoulders, each consisting of an element 15, for example in the form of a rail. On each rail relative to a shoulder a carriage runs, shown with 16. Each carriage 16 is integral at the upper part with a positioning cylinder 18, whose piston (seen in figure 8) is integral with two opposite rods 20, 22 restrained at the ends, at 21 and 23, to the shoulders. The carriages 16 bear two horizontal axles 24 and 25, which act as respective pivots for a pair of spindle-holder or roll-holder levers 26 and for a pair of control levers 28. Each control lever is connected at the upper part to the related spool-holder lever by means of a control transmission arm or connecting rod 30, articulated with respect to the said levers. To be precise (see figure 4), each control lever 28 bears a horizontal pin 29 on which the control arm 30 is pivotably supported. This arm has a C-shaped portion, as seen in plan view, which extends towards the respective spool-holder lever, and bears a second horizontal pin 31 on the branches of the C. Between this pin and the spool-holder lever 26 a load cell 32 is mounted. The spool-holder lever 26, which appropriately has a housing 27 for receiving the load cell, then extends upwards and forms a housing 34 (figure 3) for receiving the axle of a winding spindle 37. On the upper part 26' of lever 26 a locking member 35 for the spindle axis is pivotally mounted. This member is rotatable from a locking position to a free position an viceversa through operation of a cylinder-piston 36, which is also borne on the lever 26. An adjustable stop member 38 is also mounted on carriage 16, and cooperates with a surface 28' on the control lever for an initial setting; an unloading control cylinder, shown with 40, is also mounted and connected with the control lever. With respect to the carriage, the pair of roll-holder levers 26 is movable between two positions; one is a winding position, in which the levers support a spindle 37 with its axis held on a vertical plane, which also contains the axis of the pivots 24 (figures 1, 2 and 5), and the other is an unloading position (figure 3). A calender 42 is mounted in a per se known way on shoulders 13 and its axis is coplanar with the axis of the spindle, on a substantially horizontal plane. A sloping unloading surface 44 is arranged on the downstream part of the apparatus, to unload the wound rolls. A pair of barrier photoelectric cells 66 are arranged on the shoulders 13, in a position corresponding to the position of minimum distance between the periphery of the roll and the calender. In figures 8 and 9 the apparatus control diagram is shown. The load cell 32 is connected by means of an amplifier 50 to a display 52 and to a control 54; this drives a servovalve 56, which feeds one or the other chamber 18' or 18'' of the cylinder 18 by means of a motor pump 58, a tank 60 and an accumulator 62. The photoelectric cells 66 are connected to the same control 54, to which a linear potentiometer 64 is also connected. The control 54 drives servovalve 56 which feeds the chamber 18'' of the cylinder 18 by means of motor pump 58, tank 60 and accumulator 62. The apparatus described here can work both with only surface winding or with combined winding, that is central plus surface winding, using the load cells for control; or with combined winding with preset distance, using the barrier photoelectric cells for control. Obviously the scope of the invention includes a winder with just one of the above types of control. A description will be given below of the operation of the surface system (valid for both types of winding which can be realized) and then of the operation at a preset distance (which can be realized only in the condition of combined winding). The operation of the system in the condition of contact winding (for both surface draft and combined draft) can be described as follows. A first winding spindle 37 is positioned, supported in the housings or seatings 34 on the roll-holder levers 26, and it is locked with the locking devices 35, and placed in the working position (figure 1) against the calender. The web N passes along the calender and is wound onto the spindle. The directions of rotation of the driving calender or cylinder 42 and of the roll B which is being formed on the spindle are shown by the arrows in the figures. The rolling load F between the roll and the cylinder produces a force F c on the load cell. This force is detected by the cell and converted into an electric signal, then amplified and transmitted to a display system and a control system. The control system, by means of a high response proportional servovalve, allows the cylinder 18, and therefore all the roll support device, to be re-positioned in the conditions in which the set load F is reset. In summary, the operator sets the load F, which is selected according to the type of production, then in the winding phase each minimum variation with respect to this set load involves re-positioning of the cylinder 18. In fact, the winding of each coil of the web involves a variation of the load F, which is immediately reset, and therefore even winding is obtained from the beginning up to maximum diameter. At the end of winding, the control functions are cut off and the carriage 16 traverses up to the outer end of its run, after which the cylinder 40 rotates the control levers 28 and consequently the roll-holder levers 26. In this way the roll is deposited on the unloading chute 44. The return of the rod of the cylinder 40, and therefore the return of the carriage 16 towards the calender 42 allows the previous winding conditions to be set with a new spindle 37a, which has been positioned on the levers 26 in the meantime. The operation of the system in the conditions of winding at a preset distance (combined draft winding) can be described as follows: the system of barriage or barrier photoelectric cells 66 (with transmittor receiver), which is positioned at an area in which the contact band between the roll 9 and the cylinder or calender 42 is usually generated, must always stay clear or open. In fact the increase in the roll diameter tends to obscure or interrupt the barrier; when this happens, the signal coming from the photoelectric cell through the control system 54 drives the servovalve 56, which consequently modifies the position of the carriage 16 by a predetermined amount, which is detected by means of the voltage variation on linear potentiometer 64, positioned parallel to the hydraulic cylinder. A series of small movements will be added until the barrier is open again. At this point these movements will be interrupted until the barrier is obscured again. This series of small movements can be likened to a continual traverse of the carriage at a speed equal to the growth of the radius of the roll, keeping the distance between the cylinder and the roll constant. This distance is determined by the mechanical positioning of the barrier on the machine.

Claims: A winding apparatus for winding a continuous web of sheet material onto a spindle for forming a roll of sheet material, said apparatus comprising: a winding calender (42), at least a spindle-holder lever system for supporting the spindle with the axis of the spindle parallel to the axis of the calender, said lever system(s) being movable between an upright working or web winding position and a roll unloading lowered position, a movable carriage onto which the said spindle-holder lever system(s) is mounted for a horizontal traverse movement, a movement means for the carriage, a detector element for detecting a quantity relative to the winding of the web, a control system for determining the traverse of said carriage according to an increase in said winding, characterized in that said spindle-holder lever system(s) comprising a first or roll-holder lever (26) and a second or control lever (28), both levers being pivotally mounted on said carriage on parallel spaced axles (24, 25), said system(s) further comprising a control arm (30) pivotally mounted on said control lever on an axis (29) parallel to said first mentioned axes and pivotally connected to said holder lever (26) on an axis parallel to said first mentioned axis, said detector element being a load detecting element for sensing a rolling load produced at a contact area of said calender and roll. An apparatus as in claim 1 characterized in that said detector element is a load cell mounted for sensing a load between said roll holding lever (26) and said control arm. An apparatus as in claim 2 characterized in that said load cell is mounted on a pin (31) on the pivotal axis of said control arm on said roll-holder lever and is received into a housing (27) of the roll-holder lever (26).

Inventors: LOMBARDINI FRANCESCO, LOMBARDINI, FRANCESCO
Applicants: COLINES SRL, GRUPPO COLINES S.R.L.
Application year: 1992
Main classification: B65H18
IPC codes: B65H18