Description

Technical Field

[0001] The present invention relates to a metallic wire winding spool, more specifically for sawing wire. More specifically the spool is suitable for winding extremely long lengths of fine steel wire, for example with a diameter lower than 200 μm on. The present invention also relates to the use of such a spool in a wire saw apparatus. More particularly, the spool can be used to dispose off the sawing wire.

Background Art

[0002] It is known that spools for winding wire which comprise a tubular core for supporting the coil of wire, provided at its ends with flanges for containing the coil, are widely used in the industrial field. Specially when extremely long for example more than 300 km and fine wires for example with a diameter below 200 μm are wound on such spool, the spool must be specifically adapted for the purpose. The core must be able to support the pressure exerted by the wires on the core without crushing and the flanges must support the force exerted by the wires in axial direction on the flanges.

[0003] Known spools have a certain integrated construction, whose peripheral surface is intact. For example, typically the spool most commonly used to date includes a hub or a tubular core having a 260 mm traverse and a diameter of about 210 mm whereas the flange has a diameter of about 288 mm. There are no notches on the hub or on the inner side of the flanges. When used as a take-up spool and this take-up spool is full of used wires, one may want to dispose off these wires. One common way to remove the wire is torch cutting. Torch cutting, however, which will damage the spools and make the spools no longer fit for reuse. [0004] Besides, the other practice in the design of spools employed for disposal of wire on the spool is to provide U-slots in the flanges of the spool opposite to one another. The wire is then cut through with a grinding wheel through the U-slots. However, in case the wire does not need to be disposed off and the wire needs to be used twice, the spool must be able to function as a paying-off spool. Paying-off spools with U-slots have proved to provide a bad winding quality because of notch area of the flange. Particularly when the wire has long length and is extremely thin and wound at high tension, this necessitates the need for a sturdy spool. When using U-slots, the wire is pushed into the slots. When now reusing the wire and paying off, the wire can get trapped at the U-slots and lead to wire fracture.

[0005] Prior art document CH 697022 discloses a sawing wire spool enabling to dispose easily off the used sawing wire. The spool has a removable flange combined with a conical tubular core. After having removed the flange, the used sawing wire is easily disposed off because of the conical core.

Disclosure of Invention

[0006] It is an object of the present invention to provide a spool for easy disposal of the wire on said spool which is simple and inexpensive to manufacture.

[0007] It is a further object of the present invention to provide a spool which can be used as paying-off spool without unwinding difficulties and with minimum fractures of the wire.

[0008] Other objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

[0009] The present invention is embodied in a spool having a groove axially arranged on the core being aligned and continuing with radial slits in flanges. At least one piece fits said slit and is held in place in said slit by holding means to make the inner side of the flanges flat. This piece is removable for easy disposal of the wire on said spool or this piece is easy to cut for easy disposal of the wire on said spool. Because the inner side of the flanges is flat, the wire can no longer be trapped in the slit, which improves considerably the winding quality and avoids unwinding difficulties such as wire fractures.

[0010] For disposing off the wire, there are two embodiments. The first embodiment involves the removal of the piece from the slit so that there is an opening for allowing the grinding wheel to cut the wire until the groove so that it can be disposed off. The second embodiment leaves the piece in the slit but the grinding wheel cuts the piece together with the wire. In this second embodiment the piece may be made of a softer material.

[0011] In a first example, the piece may be held in place in said slit by magnetic means. For example, said piece is made from magnetic material.

[0012] In a second example, the piece may be held in place in said slit by mechanical means. For example, said piece form-fits into said slit. Said piece may also be held in place in said slit by a screw in a radial direction or in chord direction. Other mechanical means, for example, a dowel or a clamp or a spring may also be used to hold the piece in place in said slit.

[0013] In a third example, the piece may be held in place in said slit by adhesive means.

[0014] The piece may be made of metal, e.g. a metal that is softer than the main material of the spool itself for easy cutting.

[0015] The piece may also be made of polymer material, e.g. plastic, rubber. [0016] In a preferable embodiment, each flange has a pair of radial slits axially opposite to one another.

[0017] The slit has a width of 20 to 120 times the diameter of said wire, e.g. a width of 40 to 100 times the diameter of said wire, e.g. a width of 50 to 90 times the diameter of said wire.

[0018] The slit has a length of between 100 and 120% of the radial distance from said peripheral surface of said core to the outer rim of said flange, e.g. a length of between 101 and 110% of the radial distance from said peripheral surface of said core to the outer rim of said flange.

[0019] According to a particular aspect of the invention, there is provided a use of a spool as described above as a paying-off spool or take up spool in a wire saw apparatus.

[0020] According to still another aspect of the invention, there is provided a use of a spool as described above to dispose off the wire.

Brief Description of Figures in the Drawings

[0021] The invention will now be described into more details with reference to the accompanying drawings.

[0022] Figure 1 is a perspective view of a general spool according to the prior art; [0023] Figure 2 is a perspective view of a prior art spool with U-slots; [0024] Figure 3 is a perspective view of a piece fitting the slit in an invention spool; [0025] Figure 4 is a perspective view of a spool according to the invention; [0026] Figure 5 schematically illustrates the magnetic interaction in an invention spool; [0027] Figure 6 is a perspective view of another spool according to the invention;

Mode(s) for Carrying Out the Invention

[0028] Figure 1 shows a general prior art spool. With reference to Figure 1 , the reference numeral 10 designates a tubular core, which is provided at the ends with two flat flanges 12 and 14, which are mirror-symmetrically identical.

[0029] The diameter K of the flanges is 288 mm while the diameter of the tubular core L is 210 mm. The overall width M is 320 mm while the traverse N is 260 mm. The bore diameter O is 122 mm. The spool is made of stainless steel, which includes 0.1-1.5% C and 0.1-1.1 % Si and one or more elements selected from among Ni, Co, Mo, Mn, Cr and V in a total amount of 1 to 20%.

[0030] Figure 2 shows a prior art spool with a groove 16 and a slit 18. The tubular core 10 has a groove 16 axially arranged on its peripheral surface, at the opposite side, where the same groove lies. The width of the groove is 10 mm while the depth is 10 mm.

[0031] The flange 12 has a radial slit 18 from core to flange rim, groove 16 being aligned and continuing with slit 18. The slit shares the same width of the groove, and slit 18 has a length of 49 mm of the radial distance from the bottom of the groove to the outer rim of said flange.

[0032] The groove 16 connects the same two slits separately in the flange 12 and 14. Each flange has a pair of radial slits axially opposite to one another.

[0033] Figure 3 shows the piece fitting into the slit according to the invention. The invention spool now comprises one piece 20, fitting slit 18 and held in place in slit 18 to make the inner side of the flanges flat.

[0034] The piece 20 is made from magnet in order to hold in place in slit 18.

[0035] Figure 4 shows an invention spool with the piece in the slit. The spool with pieces in the slits can be used as both paying off and taking up spool. If it is necessary to dispose the wire on the spool, the piece 20 can be removable for easy disposal of the wire on the spool by grinding wheel. If it is necessary to reuse the wire on the spool again, the winding quality at slit area of the flange is good enough, since the trapping of the wire in the slit has been prevented.

[0036] Figure 5 shows the magnetic interaction between the slit area in the flange and the piece in the slit according to the above invention spool.

[0037] Figure 6 shows a spool as another subject of the invention. The metal piece 22 has a shape complementary to the shape of the slit, holding in place by mechanical force, so the inner side of the flange becomes flat again and the spool can be used as both paying off and taking up spool in wire saw apparatus. If it needs to dispose the wire on the spool, the piece 22 can easily be cut for easy disposal of the wire on said spool by grinding wheel. The same piece as piece 22 can be inserted in the corresponding slit that the spool would be used as original.