GB2175233A - Method of producing stranded electrical cable - Google Patents

Abstract

A roughened wire 2 is processed in a friction feed extrusion moulding device 4 comprising a pair of rotary members 8,9 defining an annular space 10 and a shoe member 11 facing the annular space at one end thereof. At the other end thereof is provided a multi-orifice rotary die head 13. The shoe member 11 has a wall 12 which acts to pinch the supplied roughened wire in cooperation with one of the two rotary members such that a free end P of the roughened wire contacts the other rotary member to be drawn into the annular space and compressed into a half-fused state. After that, the roughened wire is extruded into a plurality of wires by the rotary die head 13, the wires then being continuously twisted together around another wire or stranded cable 1 passing through an axial bore of rotary member 8 to produce a stranded cable. Various forms of extruding plant embodying the above device are disclosed. <IMAGE>

Description

SPECIFICATION Method and apparatus for producing stranded electrical cable Background of the invention The present invention relates to a method of producing bare stranded wires, particularly stranded cables of mild steel, and an apparatus for the same.

Recognized stranded cables are generally classified into concentric lay cables, aggregate cables and composite cables which are commonly produced by successive steps of drawing, annealing and twisting. In the drawing step, a roughened wire of a relatively large diameter is drawn to prepare a wire of a smaller diameter. The twisting step on the other hand consists in twisting a plurality of such wires together around a core wire by a twister die; six wires may be twined around a single core wire to form a concentric cable, for example, which is the simplest of all the known types of stranded cables. The twisting step may be performed before or after the annealing step as the case may be.

Thus, the conventional stranded cable production line is made up of the following three independent steps: (A) Stretching Step roughened wire < drawing machine < take-up machine (drum) (B) Annealing Step (drum) < annealing machine or furnace take-up machine (drum) (C) Twisting Step (drum) < twisting machine o take-up machine (drum) The production line, therefore, requires a large scale installation and a disproportionate area for the installation. Moreover, excessive power consumption is unavoidable because the take-up machines or drums in the successive steps (A)-(C) overlap each other.

There has been proposed various classes of methods to extrusion mould wire material, among which the conforming process and the helical process are typical ones. The conforming process is a method, as described in USP 3,765,216, in which it includes the steps of supplying material continuously into a passageway formed between a rotary wheel and a stationary shoe, and continuously extrusion moulding wires out of orifices formed in the stationary shoe. In this method, however, extrusion moulded wires are not subjected to twisting operation.On the other hand, the helical process includes, according to USP 3,884,062, the steps of extruding billets in an annular form under static hydraulic pressure from between the primary die of helical configuration and the piercing mandrel, subjecting the extruded billets to machining operation by a rotary abutment in a similar manner to the operation of lathes, and extrusion moulding the product out of the die attachment immediately in front of the abutment. This process is capable of extrusion moulding large diameter billets into wireshaped products for a long operational time, thus providing less downtime than the conventional extrusion moulding. However, this method is considered to be suitable for production on a relatively small scale in view of its being an uncontinuous procedure and substantial inability to wind up the extrusion moulded products in helical form.

Summary of the invention The present invention has been completed by combining the features of the helical process in which products are extruded in helical form hard to handle and the conforming process which is capable of extrusion moulding continuously. As a result, the extrusion moulding and the twisting operation can be done continuously.

It is an object of the present invention to provide a method and apparatus for the production of standard cables in which drawing, annealing and twisting operations are performed in an uninterrupted flow so as to cut down the overall size of the apparatus, space requirement and power consumption.

In one aspect of the invention, there is provided a method of producing a stranded electrical cable comprising the steps of rotating a first rotary member axially in a counterclockwise direction, said first rotary member having first and second axial end portions; surrounding part of said first rotary member by means of a second rotary member to define an annular space therebetween, said second rotary member having first and second axial end surfaces, said first axial end portion of the first rotary member projecting outside the second rotary member; providing a guide wall around said first rotary member at said first axial end portion thereof in slantwise facing relation to said annular space first at a predetermined distance from said first axial end surface of the second rotary member but gradually extending closer thereto; supplying a length of roughened wire having a diameter smaller than said predetermined distance along said guide wall at a point where said guide wall and said first axial end surface cooperate to pinch a free end of said length of roughened wire until the roughened wire contact the first rotary member and draw said roughened wire into said annular space through friction provided by the rotating first rotary member; continuing to draw said roughened wire such that said roughened wire is wound around said first rotary member; blocking said annular space at said second axial end portion of the first rotary member by means of rotary die assembly having a plurality of dies; rotating said rotary die assembly in a clockwise direction to extrusion mould a plurality of wires; and twisting continuously said plurality of wires together to produce a stranded cable.

In another aspect of the invention, there is further provided an apparatus for producing a stranded electrical cable including one stranded cable producing unit, said unit comprising a first rotary member axially rotatable in a counterclockwise direction and having first and second axial end portions; a second rotary mem ber provided in association with said first rotary member to define an annular space therebetween, said second sylindrical rotary member having first and second axial end surfaces, said first axial end portion of the first rotary member projecting beyond the first axial end surfaces of the second rotary member, a shoe member provided around said projecting part of the first rotary member and having a guide wall facing said annular space at a predetermined distance from said first axial end surface of the second rotary member but gradually extending closer thereto, said guide wall having a shouldered portion offset by predetermined distance; means for supplying a length of rengthened wire having a diameter smaller than said predetermined distance to bring a free end of said length of roughened wire into contact with the rotating first rotary member at a point where said guide wall and said first axial end surface cooperate to pinch said free end of the roughened wire such that said length of roughened wire is drawn into the annular space to be wound around the first rotary member to proceed toward said second axial end portion of the first rotary member; a rotary die head provided at said second end portion of the first rotary member and having a inner surface facing said annular space and an outer surface on opposite side thereof, said rotary die head having a plurality of passageways bored therein and having openings both in the inner and outer surfaces, said rotary die head further having a plurality of dies in said inner surface at said openings, said rotary die head blocking the proceeding roughened wire to compress the same into a half-fused state and rotating in a clockwise direction such that said plurality of dies cut said roughened wire in a half-fused state and extrusion mould a plurality of wires; and means for holding said plurality of extrusion moulded wires at one point such that it is twisted to produce a stranded wire.

Brief description of the drawings Drawings illustrate embodiments of the present invention, in which: Figure 1 is a perspective view of the entire construction of a stranded cable producing apparatus; Figure 2 is another perspective view of the stranded cable producing apparatus of Figure 1; Figure 3 is a cross section of a partly broken en larged view of the interior of the stranded cable producing apparatus, into which a roughened wire is about to be inserted; Figure 4 is a view similar to Figure 3 but showing that the roughened wire has been inserted thereinto; Figure 5 is a perspective view of a rotary die head used in the interior of the apparatus; Figure 6 is a front view of the rotary die head extrusion moulding wires which are being twisted;; Figure 7 is a cross section of the interior of the apparatus according to another embodiment of the invention; Figure 8 is a cross section of the interior of the apparatus according to a further embodiment of the invention; Figure 9 is a cross section of the interior of the apparatus of a still further embodiment of the invention; Figure 10 is a cross section of the interior of the apparatus of a still further embodiment of the invention; Figure 11 is a cross section of the interior of the apparatus of a still further embodiment of the invention; Figure 12 is a schematic view of a multi-layer concentric stranded cable production system; Figure 13 is a schematic view of a hard drawn SB stranded cable production system; Figure 14 is a schematic view of a composite stranded cable production system; and Figure 15 is a schematic view of a modification to the system of Figure 14.

Detailed description of the embodiments Referring to Figures 1 and 2, there is shown an entire construction, in perspective, of a stranded cable manufacturing apparatus embodying the present invention. A length of small diameter roughened wire 1 and a length of large diameter roughened wire 2 are supplied from carriers (not shown) to a straightening device 3 and an extrusion moulding device 4, respectively. Said small diameter roughened wire 1 supplied to the straightening device 3 is further supplied to the extrusion moulding device 4. The large diameter roughened wire 2 is processed within the extrusion moulding device 4 to be extruded out of the device in the form of a plurality of wires 5. Said wires 5 are held by a twister holder 6 at one point.

Figures 3 and 4 are fragmentary sectional view of the interior of the device in more detail. A first cylindrical rotary member 8 is provided within the device axially rotatably in a counterclockwise direction and has first and second end portions 81 and 82. Further, a second cylindrical rotary member 9 is positioned to coaxially surround said first cylindrical rotary member 8 to define an annular space 10 therebetween. Said second cylindrical rotary member 9 axially rotates counterclockwise at a speed lower than the first cylindrical rotary member 8 and has first and second axial end surfaces 91 and 92z The first axial end portion 8, of the first cylindrical rotary member 8 projects beyond said first axial end surface 9, of the second cylindrical rotary member 9. Around said projecting part of the first cylindrical rotary member 8, there is provided a shoe member 11 which has a guide wall 12 extending radially and facing said annular space 10 at a predetermined distance from said first axial end surface 9, but gradually extending closer thereto and said guide wall 12 has a shouldered portion 12' offset by a predetermined distance.

Said length of roughened wire 2 is supplied from a carrier (not shown). Said wire has a diameter smaller than said predetermined distance. During automatic or manual supplying operation of the roughened wire 2 along the guide wall 12, a free end of the roughened wire 2 is brought into contact with the rotating first cylindrical rotary member 8 at a point P where said guide wall 12 and said first axial end surface 91 cooperate to pinch said free end of the roughened wire such that said length of roughened wire is drawn into the annular space 10 through friction provided by the rotating first cylindrical rotary member 8 to be would around the first cylindrical rotary member 8 to proceed toward said second axial end portion 8 of the first cylindrical rotary member 8.

At said second end portion of the first cylindrical rotary member 8, there is provided a rotary die head 13 which has an inner surface 14 facing the annular space 10 and an outer surface 16 on an opposite sides thereof. Said rotary die head has a plurality of passageways 15 bored therein and has openings both in the inner and outer surfaces 14 and 16 (Figures 5 and 6). Said rotary die head 13 further has a plurality of dies 17 in said inner surface 14 at said openings. Said rotary die head 13 is adapted to block the proceeding roughened wire 2 to compress the same into a half-fused state and rotates in a clockwise direction such that said plurality of dies 17 cut said roughened wire 2 in a half-fused state and extrusion mould a plurality of wires 5. Said plurality of extrusion moulded wires are held at one point by the twister holder 6 as best shown in Figure 2.Since the rotary die head 13 rotates in a clockwise direction, they are twisted into a stranded wire 7. In twisting, a small diameter roughened wire 1 may axially be stretched through the extrusion moulding device and the extrusion moulded wires 5 may be would above said wire 7 to produce a multi-layer concentric cable having a core as shown in Figure 6.

Referring to Figure 5, said inner surface 14 of the rotary die head 13 is generally of saw-toothed shape having a plurality of faces 14' oriented slantwise with respect to the annular space 10. The afore-mentioned plurality of dies 17 are formed in said respective faces 14' which are arranged radially.

Referring to Figure 7, there is shown an another embodiment of the stranded cable manufacturing apparatus according to the present invention in which first and second rotary members 108 and 109 of truncated conical shape are so arranged to define an annular space 110 which is inclined relative to the axis of the apparatus as illustrated.

A further embodiment is illustrated in Figure 8, in which first and second rotary members 208 and 209 of cylindrical shape are axially juxtaposed to define an annular space 210 extending radially outwardly in perpendicular relation to the axis of the apparatus. Within said first rotary member 208, a rotary die head 213 is disposed such that a die 217 faces the annular space 210 radially outwardly in a slantwise fasion. On the other hand. Figure 9 illustrates a still further embodiment in which first rotary member 308 is surrounded by a second rotary member 309 as the embodiment of Figures 3 and 4. In such a structure, a rotary die head 313 may face the annular space 310 from the twister side.

Referring to Figure 10, the extrusion moulding device comprises a rotatable shoe member 411 which is mounted in a position inclined at an angle 0 relative to the axis of the inner rotary member 408. The shoe member 411 feeds the wire 402 successively into the annular space 410 while rotating substantially in the same manner as the inner rotary member 408. It will be seen here that the rotary shoe member 411 can feed the wire 2 but by an amount which is only about half a pitch (180 ) and, hence, it must be assisted by a stationary shoe member which feeds the wire by the other half pitch. The reference numeral 411' denotes a guide shoe. Figure 11 shows a still further embodiment of the present invention. The device comprises a rotatable and axially movable shoe member 511 for feeding out the wire 502.This shoe member 511 is divided into a plurality of equal parts which are individually mounted to the inner rotary member 508 by key members 520.

With this construction, each of the shoe parts can rotate integrally with the inner rotary member 508 and move axially relative to the member 508 through a corresponding key 521. One end of each shoe part 511' is engaged by an inclined end of a stationary shoe member 511'. When the member 508 is driven for rotation, the shoe member 511 will feed the material 502 pitch by pitch into the annular space 510 rotating integrally with the member 508 and moving axially in contact with the inclined end of the stationary shoe member 511.

The movable shoe member 518 is surrounded by a shoe holder 519. The reference numeral 511 denotes a stationary guide shoe member.

Referring to Figure 12, a system for producing multi-layer concentric cable is illustrated in a schematic diagram. The system comprises first to third cutting and extrusion moulding units I, II, and Ill.

Each of the units I-Ill is constituted by the extrusion moulding device 4 and twister holder 6 depicted in Figures 1 and 2. A core wire 1 is supplied from the carrier to the first unit I which twists wires 5 about the core 1 to form a first layer. The second unit II twists other wires 5' about the first layer to form a second layer. The third unit lli twists still other wire 5" around the second layer to form an outermost layer. The multi-layer concentric cable 21 is wound on the take-up drum 22 through the capstan 23. In this way, a serial operative connection of a plurality of units can produce a concentric cable having a desired number of layers about the core wire 1.

The intermediate unit II has two basic units I and the outlet unit Ill has three basic units I.

Another system is shown in Figure 13 which is designed to produce a hard drawn SB cable. A concentric cable 21 coming out of the basic unit I has its diameter reduced by continuous drawing machine 24 which is equipped with a plurality of stretcher rollers 25 or dies. The cable 21 is then processed by a known puncher type twisting machine 26 to have a necessary twist patch. Though not shown in the drawing, a finish die is positioned in the system to provide the cable from the machine 26 with a uniform diameter.

Another system is shown in Figure 14 which is constructed to produce a composite cable. This system comprises a plurality of basic units 2 and a single twisting machine 27 of a take-up rotary type.

The basic units I are positioned radially with re spect to the twisting machine 27. The machine 27 has a capstan 29 and a take-up drum 22 thereinside. The individual basic units I product contric cables 21 which are then fed to the twisting machine 27. The machine 27 driven for rotation processes the input concentric cables 21 into a composite cable 29. In the previously described manner, the product 29 is wound on the take-up drum 22 via the capstan 23.

A modified form of the system shown in Figure 14 is illustrated in Figure 15. The system of Figure 15 is essentially similar to that of 14 except for a separate arrangement of the capstan 23 and takeup drum 22. Specifically, the system of Figure 15 comprises a combination of a rotary twisting machine 30 with capstans 31 and a part of take-up machines 32, these machines 30 and 31 are operatively connected together by a synchronous rotation mechanism (not shown). The modified system of Figure 15 is advantageous over the system of Figure 14 in that it can be operated continuously and need only be entirely stopped when the takeup machines 32 are changed from one to the other.

The present invention has been described concentrating on the production of concentric lay cables except for Figures 14 and 15. It will be apparent to those skilled in this art that multiple wires prepared by the extrusion moulding machine 4 of the basic unit I, for example, can readily be twisted to form an aggregate cable and are applicable to the production of various kinds of compressed cables.

It will be seen from the foregoing that the present invention provides a method which not only establishes an uninterrupted continuous flow throughout drawing, annealing and twisting steps but permits a desired cable to be produced despite any change in the size through a simple replacement of a part of the component element i.e. dies or a rotary head.

Claims (14)

1. A method of producing a stranded electrical cable comprising the steps of rotating a first rotary member axially in a counterclockwise direction, said first rotary member having first and second axial end portions; surrounding part of said first rotary member by means of a second rotary member to define an annular space therebetween, said second rotary member having first and second axial end surfaces, said first axial end portion of the first rotary member projecting outside the second rotary member; providing a guide wall around said first rotary member at said first axial end portion thereof in slandwise facing relation to said annular space first at a predetermined distance from said first axial end surface of the second rotary member but gradually extending closer thereto;; supplying a length of roughened wire having a diameter smaller than said predetermined distance along said guide wall at a point where said guide wall and said first axial end surface cooperate to pinch a free end of said length of roughened wire until the roughened wire contact the first rotary member and draw said roughened wire into said annular space through friction provided by the rotating first rotary member; continuing to draw said roughened wire such that said roughened wire is wound around said first rotary member; blocking said annular space at said second axial end portion of the first rotary member by means of rotary die assembly having a plurality of dies; rotating said rotary die assembly in a clockwise direction to extrusion mould a plurality of wires; and twisting continuously said plurality of wires together to produce a stranded cable.

2. A method according to claim 1, further including a step of rotating said second rotary member in said counterclockwise direction.

3. A method according to claim 2, wherein said rotation of the second rotary member is slower than that of the first rotary member.

4. A method according to claim 1, wherein said twisting step includes a step of holding the fed-out wires therefrom at one point.

5. A method according to claim 4, further including a step of feeding out continuously another wire or another stranded cable from an axial bore of said second rotary member concurrently with said plurality of wires to be subjected to said twisting step.

6. A method according to claim 5, wherein said twisting step includes a step of twisting said plurality of wires about said another wire or another stranded cable to produce a stranded cable.

7. An apparatus for producing a stranded electrical cable including one stranded cable producing unit, said unit comprising a first rotary member axially rotatable in a counterclockwise direction and having first and second axial end portions; a second rotary member provided in association with said first rotary member to define an annular space therebetween, said second cylindrical rotary member having first and second axial end surfaces, said first axial end portion of the first rotary member projecting beyond the first axial end surfaces of the second rotary member;; a shoe member provided around said projecting part of the first rotary member and having a guide wall facing said annular space at a predetermined distance from said first axial end surface of the second rotary member but gradually extending closer thereto, said guide wall having a shouldered portion offset by predetermined distance; means for supplying a length of roughened wire having a diameter smaller than said predetermined distance to bring a free end of said length of roughened wire into contact with the rotating first rotary member at a point where said guide wall and said first axial end surface cooperate to pinch said free end of the roughened wire such that said length of roughened wire is drawn into the annular space to be wound around the first rotary member to proceed toward said second axial end portion of the first rotary member;; a rotary die head provided at said second end portion of the first rotary member and having a inner surface facing said annular space and an outer surface on opposite sides thereof, said rotary die head having a plurality of passageways bored therein and having openings both in the inner and outer surfaces, said rotary die head further having a plurality of dies in said inner surface at said openings, said rotary die head blocking the proceeding roughened wire to compress the same into a half-fused state and rotating in a clockwise direction such that said pluality of dies cut said roughened wire in a half-fused state and extrusion mould a plurality of wires; and means for holding said plurality of extrusion moulded wires at one point such that it is twisted to produce a strand wire.

8. An apparatus according to claim 7, wherein said inner end of the rotary die head is generally of saw-toothed shape having a plurality of faces oriented slantwise with respect to the annular space, said plurality of dies being formed in said respective faces.

9. An apparatus according to claim 8, wherein said plurality of faces is arranged radially.

10. An apparatus according to claim 9, wherein said second rotary member is adapted to rotate axially counterclockwise.

11. An apparatus according to claim 7, wherein said second rotary member is positioned to coaxially surrounded said first cylindered rotary member.

12. An apparatus according to claim 7, wherein said first and second cylindrical rotary members are axially juxtaposed.

13. An apparatus according to claim 11, wherein said first and second cylindrical rotary members are generally of a truncated conical shape.

14. An apparatus according to claim 11, wherein said shoe member includes a stationary member.