Conical coiling of wire on a spool with a cylindrical core and two straight flanges mounted perpendicularly to the cylindrical core

Abstract: The invention relates to a method of coiling wire on a spool with a cylindrical core and two straight flanges mounted perpendicularly to the cylindrical core, whereby the wire is wound in layers and each layer comprises a number of adjacent windings and whereby on the completion of each layer the direction of layer formation is reversed and the coiling operation continues until the desired amount of wire is wound on the spool, whereby the wire is coiled conically on the spool with a cylindrical core by starting with a first layer with a minimum number of windings, after which the coiling operation proceeds whereby for at least part of the coiling operation the number of convolutions per layer is gradually increased.

Description: This invention relates to a method of coiling wire on a spool with a core and two straight flanges mounted perpendicularly to the core axis, whereby the wire is wound in layers and each layer comprises a number of adjacent windings and whereby on the completion of each layer the direction of layer formation is reversed and the coiling operation continues until the desired amount of wire is wound on the spool. Such a method is well-known. This known method uses a spool with a cylindrical core and straight flanges mounted perpendicularly to the core, whereby the wire is coiled around the core and on completion of a layer of adjacent windings, coiling is continued in reverse direction to form the next layer, this method being repeated until the required amount of wire has been coiled on the spool. The wire is usually bent to a certain extent prior to coiling, which facilitates the coiling method. Such a method has the disadvantage that it produces a spool coil in which the windings of each layer support each other but in which there is nevertheless a danger that when the core is positioned vertically the windings may slip over each other, starting with the top layer, and slide down the core, which leads to tangling of the wire, and sometimes to such an extent that the spool and the wire on it are practically unusable. Bending the wire prior to the coiling operation, together with the torsional deformation which often occurs during unwinding, frequently leads to problems or even to the wire breaking during the unwinding operation. There is also known from the U.S.A. patent No. 3.218.004 as well as GB-A-852 677 and US-A-4 253 298 a method of conical coiling wire on a spool with a cylindrical core and with two straight flanges mounted perpendicularly to the cylindrical core; FR-E-50 994 describes a method of conical winding on a cylindrical core without flanges. This U.S.A. patent 3.218.004 teaches a method for forming a tapered or conical coil on the cylindrical core between the two straight flanges of the spool. In this U.S.A. patent 3.218.004, all the successive windings of one layer are distributed over the whole distance between the two straight flanges. The wire is coiled conically on the spool with cylindrical core according to this U.S.A. patent 3.218.004 because the wire is wound in successive layers between the two straight flanges and each layer comprises a same number of successive windings, whereby the speed of winding is gradually increased from the bottom or lower flange to the top or upper flange. A disadvantage of this known method is that the distance between each pair of successive windings of a layer is changing so that many windings of such a layer do not support each other, particularly at the top of the spool. Another disadvantage is that the successive layers do not support each other, so that there is a great danger that when the core is positioned vertically, the windings of one layer are sliding down the core, which leads to tangling of the wire. In the method of FR-E-50 994 the number of windings is gradually increased during part of the winding operation. The object of the present invention is to provide a method, whereby the above-mentioned disadvantages are eliminated or the object of the present invention is to provide a method of forming a coil on a spool, whereby the successive windings or convolutions support each other in such a way as to substantially prevent their slipping over each other and sliding down the core. This object is achieved by the method according to the invention which is characterized in that the wire is coiled conically on a spool with a core by starting with a first layer with a minimum number of windings, after which the coiling operation proceeds whereby for at least part of the coiling operation the number of windings or convolutions per layer is gradually increased. According to this method, coiling on a core with two straight flanges, may start at the lower flange with a minimum number of windings, whereby this minimum number may be for example one winding or convolution. After the formation of the first layer with a minimum number of windings, coiling may be continued in the same direction at increased pitch for a short time if desired, after which the direction of layer formation is reversed to form a second layer of windings. The second layer may be formed until the last winding touches the lower flange. The direction of layer formation is then again reversed to form a third layer of windings. In this way, wire is wound into a conical coil on a core, whereby the adjacent windings support each other in such a way as to substantially prevent their slipping over each other and sliding down the core. It is a further advantage of the present invention that the common practice of bending the wire prior to the coiling operation is no longer necessary, thereby avoiding the problems caused by prebending when the wire is put to use. In particular, the method according to the invention may be carried out in such a way that once a predetermined volume of wire has been coiled over the whole length of the core to form the first conical section of the coil, the number of convolutions per layer remains constant. This is due to the fact that after the formation of a number of layers in which the number of windings or convolutions is increased in each successive layer, the point is reached where the first and the last windings of a layer lie against the lower or bottom flange and the upper or top flange respectively. From this point on, the number of windings per layer is kept constant, whereby the direction of layer formation is reversed on reaching the lower flange or the upper flange, as the case may be. The volume of the first conical section can be determined in advance, whereby the number of windings in the first layer, the increase in pitch of the layer formed after the first, third, fifth, etc. layer and the diameter of the wire are of great importance ; the volume of the first conical section can be controlled on an experimental basis. In the method described above, a spool with straight flanges mounted perpendicularly to the core axis has been applied advantageously whereby the outside diameter of the operative part of the lower flange may be larger than the outside diameter of the operative part of the upper flange and whereby the difference between the two diameters may be equal to at least twice the greatest thickness of the first conical section. The flanges may of course have different outside diameters, whereby both upper and lower flanges extend slightly beyond the section of the flange supporting the coil. The greatest thickness of the first conical section may equal the length of the base of the triangular cross section of the first conical section whereby the hypotenuse of the said triangular cross section starts at the intersection of the cylindrical core and the upper flange and ends at the bottom flange. Further layers of wire may be wound on this hypotenuse in such a way that each layer wound has an equal number of windings. In order to insure that all windings are adequately supported, it is important that the outside diameter of the lower flange should exceed that of the upper flange by an amount equal to at least twice the thickness of thickness part of the first conical section. A further object of the invention is a spool with a wire coil characterized in that the wire is coiled conically on the spool, whereby the coiling is executed according to the method as described in the present invention. If desired, the spool core may be a cardboard cylinder on which detachable flanges are mounted. The invention will now be illustrated with reference to the drawing, wherein the only figure 1 shows a cross-section of a spool consisting of a cylindrical core and two straight flanges mounted perpendicularly to this core with conically coiled wire on this spool according to the invention. In figure 1 the spool 1 has a cylindrical core 2, a lower flange 4 and an upper flange 5. Both lower and upper flanges are straight and mounted perpendicularly to the cylinder core 2. Such a spool is known from the U.S.A. patent No. 3.218.004. In conical coiling according to the invention, coiling may commence or starts against the straight lower flange and a first layer comprising a minimum number of windings, for example one winding, will be formed, after which, or if desired after a brief continuation of the coiling operation at increased pitch or not, in the upward direction ; the direction of layer formation is reversed, so that a layer is then formed in the direction of the lower flange. When this layer reaches the lower flange, the direction of layer formation is again reversed and coiling continues to form a third layer until the last convolution or winding of the third layer is wound directly on to the cylinder core, after which, or if desired after a brief continuation of coiling at increased pitch, the direction of layer formation is again reversed, etc. Coiling in this manner is continued until a first conical section 3 has been formed, whereby the outer boundary of which is constituted by the layer of windings which extends from the intersection between the cylindrical core and the straight upper flange to the point at which the last convolution at the other extremity of the same layer meets the lower flange. The greatest thickness 6 of the first conical section is important in the determination of the dimension of the lower flange 4 with respect to the dimension of the upper flange 5. The outside diameter of the two flanges differs by an amount equal to at least twice the dimension of the said part 6 of the first conical section. After formation of the first conical section, coiling continues, whereby the number of windings per layer remains constant and equal to the number of windings in the outer layer of the above described first conical section. The full spool coiled according to this method offers excellent stability of the wire coil ; the end of the wire at the last convolution can be fastened in a simple manner so that the spool and coil can be handled without difficulty. Unwinding wire from such a spool will also present no problems.

Claims: Method of coiling wire on a spool with a core and two straight flanges mounted perpendicularly to the core axis, whereby the wire is wound in layers and each layer comprises a number of adjacent windings and whereby on the completion of each layer the direction of layer formation is reversed and the coiling operation continues until the desired amount of wire is wound on the spool, characterized in that the wire is coiled conically on the spool (1) with a core (2) by starting with a first layer with a minimum number of windings, after which the coiling operation proceeds whereby for at least part of the coiling operation the number of convolutions per layer is gradually increased. Method according to claim 1, characterized in that on the completion of a first conical section (3) of a predetermined volume, whereby the said section extends over the whole surface of the core (2), the number of windings per layer is kept constant. Method according to claim 2, characterized in that a spool is used, whereby the outside diameter of the operative part of the lower flange (4) is greater than the outside diameter of the operative part of the upper flange (5), the difference between the two outside diameters being at least twice the greatest thickness (6) of the first conical section (3). Spool with wire coiled thereupon, characterized in that the wire is coiled conically on the spool (1) according to the methods described in one or more of the claims 1 to 3.

Inventors: ANSEEL FREDDY, COSAERT PIERRE, ANSEEL, FREDDY, COSAERT, PIERRE
Applicants: BEKAERT SA NV, N.V. BEKAERT S.A.
Application year: 1987
Main classification: B65H55
IPC codes: B65H55