METHOD OF WINDING A STRIP OF UNIFORM WIDTH INTO A CYLINDRICAL STRIP ROLL

Abstract: When winding a strip of uniform width onto a rotating core for forming a cylindrical strip roll the length (L) of which is several times the strip width (B) and the end faces of which are located in planes (11A, 11B) which are perpendicular to the axis (12) of the roll, the winding is controlled such that the positions in the strip roll where the hand of winding of the strip is reversed are distributed circumferentially in a controlled manner.

Description: Method of winding a strip of uniform width into a cylindri¬ cal strip roll The invention relates to a method of winding a strip of uniform width onto a rotating core for forming a cylindrical strip roll the length of which is several times the width of the strip and the end faces of which are located in planes which are perpendicular to the axis of the roll, in which during the winding the core and a guide for the running-on strip are reciprocated axially relative to one another over a distance equal to the distance between the end face planes and in such a manner that radially successive, substantially smooth strip layers are formed which extend from one end face plane to the other. When winding strips in the above-stated manner it is difficult to produce sufficiently smooth roll end faces and to obtain the desired cylindrical shape of the roll, because at the ends of each strip layer a tapering open space is formed outside the outermost turn. The outermost turn of the next succeeding strip layer therefore is not supported throughout the circumference. As a consequence, the outermost turn of each layer tends to "cant" into the open space. This disadvantage is avoided by carrying out the winding in accordance with the invention, namely by controlling the relative axial movement of the core and the strip guide such that the positions where the hand of winding of the strip is reversed are distributed circum- ferentially in a controlled manner. When winding strip in accordance with the invention provision is thus made for the positions where the "leading" band edge, that is, the band edge which during the winding- on of a strip layer faces the end face plane the strip approaches and which then becomes the "lagging" band edge when the hand of winding of the strip is reversed, touches the end face plane to be placed at predetermined locations along the circumference of the roll. Instead of permitting the locations of these positions to be determined by chance, such as by the random influence of unavoidable backlash or inaccuracies in the transmission of motions or in the sensing of positions, the winding is controlled such that the positions where the hand of winding of the strip reverses are placed in accordance with a predeter- mined pattern. Of course, a certain tolerance in the placing of the reversing positions is necessary. The locations of the reversing positions may be chosen differently depending on, for example, the strip width, the desired pitch of the strip turns, the type of strip, the strip material, the roll sizes, and so on. For example, the locations may be chosen such that one band edge touches one of the end face planes at or near a number of radii having a uniform circumferential distribution, the touching positions shifting successively from one radius to the next adjacent radius. The radii of one of the end face planes may be located in the same axial planes as the radii at which the touching positions at the other end face plane are located but may also be located in axial planes between the axial planes containing the radii of the first end face plane. Naturally, the just-mentioned locations are only non-limiting examples. The invention may be carried out using known winding machines constructed such that they permit accurate control of the winding. In actual practice it is preferred to use computer-controlled equipment which includes means whereby the operator may set the current values of the variables, such as strip width, length of the roll and desired pitch. The invention is explained in greater detail herein- after with reference to the accompanying diagrammatic drawing. FIG. 1 is a diagrammatic plan view of a winding machine used for carrying out the winding method according to the invention; FIG. 2 is a diagrammatic representation of the core onto which the strip is wound and shows an example of the location of the positions where the hand of winding of the strip is reversed. Apart from the control system the winding machine diagra matically shown in FIG. 1 may be made in accordance with SE-B-403 762 to which reference is made for an explanation of the details. The winding machine will be described here only to the extent necessary for an under- standing of the winding method according to the invention. The winding machine comprises a winding disc or bobbin 11 which is mounted for rotation about an axis 12 and forms a core onto which a strip B of uniform width b and uniform thickness is to be wound to form a circular cylindrical strip roll of the length L. The bobbin 11 is rotated about the axis 12 by a drive unit 13 and is axially reciprocated over a distance equal to the length L during the rotation. A stationary strip guide 14 forms part of the winding machine. A computerzied control unit 15 controls the rotational and axial movements of the drive unit 13. As the winding is being carried out the control unit is continuously supplied with information of, among other things, the axial position of the bobbin relative to the strip guide 14. FIG. 2 diagrammatically shows how the strip B is wound onto the bobbin 11. In the figure the end face planes of the strip roll are represented by two circles 11A and 11B. These end face planes are also indicated in phantom lines in FIG. 1 where they coincide with the inner sides of the flanges of the bobbin. FIG. 2 also shows the axis 12 of rotation of the bobbin. The end B 1 of the strip B is applied to the bobbin such that the end of one of the strip edges touches the end face plane 11A on a radius RAl. Then the strip is wound onto the bobbin with a pitch s determined by the control unit until the strip edge facing the end face plane 11B touches that end face plane on a radius RBI which is angularly offset by one-sixth of a turn from the radius RAl. The hand of winding of the strip, that is, the direction of movement of the bobbin, is reversed at the radius RBI and the strip is then wound in a new strip layer until the strip edge facing the end face plane 11A touches that face plane at a radius RA2 which is angularly " BUR offset by one-third of a turn from the radius RA2 and thus by one-sixth of a turn from the radius RBI. The winding of the third strip layer then takes place such that the strip edge facing the end face plane 11B touches that end face plane at a radius RB2 which is angularly offset by one-third of a turn from the radius RAl. During the winding of the fourth strip layer the strip edge facing the end face plane 11A touches that face plane at a radius RA3 which is angularly offset by one-third of a turn from the radii RAl and RA2, and during the winding of the fifth strip layer the strip edge facing the end face plane 11B touches that end face plane at a radius RB3 which is also angularly offset by one-third of a turn from the radii RBI and RB2. Then the sixth strip layer is wound such that the strip edge facing the end face plane 11A touches that plane at the radius RAl. The winding of the strip between the "touching" positions is indicated by a phantom line in FIG. 2. The described winding pattern is then repeated until the strip roll is completed. Naturally, the winding need not be carried out in accordance with the above-described pattern which is only to be taken as an example. The two sets of radii RAl, RA2, RA3 and RBI, RB2 and RB3 need not necessarily be angularly offset relative to one another as described, and the radii at one end face plane may thus be in the same axial planes as the radii at the other face plane. Moreover, it is within the scope of the invention to arrange, in a manner known per se, for the outermost strip turns to run parallel to the end face planes through a smaller or greater centre angle.

Claims: Claim A method of winding a strip of uniform width onto a rotating core for forming a cylindrical strip roll the length of which is several times the width of the strip and the end faces of which are located in planes which are perpendicular to the axis of the roll, in which during the winding the core and a guide for the running-on strip are reciprocated axially relative to one another over a distance corresponding to the distance between the end face planes and in such a manner that radially successive, substantially smooth strip layers are formed which extend from one end face plane to the other, characterised in that the axial relative movement of the core and the strip guide is controlled such that the positions in the strip roll where the hand of winding of the strip is reversed are distributed circumferentially in a controlled manner.

Inventors: HENRICSSON CARL, HENRICSSON, CARL
Applicants: AKV I KOPPARBERG AB
Application year: 1983
Main classification: B65H81
IPC codes: B65H54