Patent Application
20080104827
The invention relates an apparatus and method for manufacturing a helically wound conductor.
There are commercial applications in which a wound conductor is used as an electrical conductor or antenna. Such a conductor includes a central core having multiple wires twisted around the core in an axial direction. Such constructions are typically formed by a tubular strander that twists multiple wires together to create a wound finished conductor.
Conventional tubular stranders axially feed a core strand along a tubular feed core path. Multiple wire components are fed radially inward along respective feed paths to intersect the core strand. A rotation is initiated in the multiple wire components as they intersect the core. A helically twisted multi-strand conductor results.
While working well, conventionally available stranders are ill-equipped to make certain wire constructions where the core strand is weak in bending rigidity and where the twist geometry of the resulting wound conductor must be carefully controlled in order to insure proper wound conductor performance characteristics. Existing stranders have difficulty in maintaining the core strand and multiple wire components in the desired configuration within objective specifications. Moreover, wires brought radially inward to a core strand by means of conventional stranders are generally uncontrolled and may crossover each other during the twisting operation. The wound conductor that results may be non-uniform and may exhibit performance anomalies.
Additionally, wound conductors made from existing stranders are typically left with a residual twist in the wire construction. Residual twist is the force within a wire construction that makes the conductor tend to wind or unwind itself. Such forces are undesirable and removing them is important to a well-behaved cable construction and useful product.
Commercially available stranders, therefore, lack the means for maintaining a proper spatial relationship between radial wires and a core strand as the radial wires are fed into an intersecting relationship with the core strand. Improper spatial relation between the feed wires and the core strand will generally result in a faulty twist geometry. Such stranders further lack a means for efficiently eliminating residual twist in the resultant cable construction in order to prevent the cable from an undesirable and uncontrolled winding or unwinding.
A need accordingly exists for a tubular strander that can maintain an optimal spatial relationship between radially fed wire conductors and an axial core strand while the conductors are rotated into a wound conductor construction. Such a tubular strander should allow for careful control of the approach angle between the radial wire conductors and the conductor core and be capable of maintaining a desired pitch of finished product. Moreover, the needed apparatus should provide the means for eliminating residual twist in the wire construction and the finished product.
According to one aspect of the invention, apparatus is disclosed for making a helically wound conductor of the conductor type having an axial cable core and one or more secondary strand(s) helically wound around the cable core. The apparatus comprises: a pull mechanism for axially advancing the cable core and a guide mechanism for axially directing the secondary strand(s) from a location offset from the cable core toward the cable core at a common approach angle. A mandrel body is disposed at a forward end of the apparatus, the mandrel body having an axial passageway extending from a rearward to the forward end of the mandrel body dimensioned to axially receive the cable core therethrough and a forward radiused end positioned to intercept the secondary strand(s). The secondary strand(s) and the mandrel are rotated about the cable core.
Pursuant to another aspect of the invention, the secondary strand(s) converge on the mandrel radiused end at a common approach angle and tangentially intersect respective locations of the mandrel radiused end.
According to another aspect of the invention, an overtwister assembly is disposed to receive the helically wound conductor from the mandrel body. The overtwister assembly includes a housing having a conductor receiving inlet and a conductor discharging outlet, and one or more rotating pulley(s) disposed within the housing positioned to engage the wound conductor. Stress forces are imparted into the conductor and removed from the conductor between the housing inlet and outlet by the pulley(s), whereby conditioning the cable conductor and preventing the cable conductor from winding and unwinding in an uncontrolled manner.
Pursuant to further aspect of the invention, a method for making a wound conductor includes: feeding a cable core along a feed path; axially guiding one or more secondary strand(s) from a location offset from the cable core toward the cable core at an approach angle; routing the cable core through a forwardly disposed mandrel body; intersecting a radiused forward end of the mandrel body by the secondary strand(s); routing the secondary strand(s) over the radiused forward end of the mandrel body to an intersection with the cable core; and rotating the secondary strand(s) and the mandrel body about the cable core to create a finished wound conductor. In another aspect of the invention, the method includes imparting an overtwist into the finished wound conductor to rid the finished wound conductor of residual stress forces.
The invention will be described by way of example and with reference to the accompanying drawings in which:
With initial reference to
An array of circumferentially disposed, spaced apart through bores or outlets 28 extend through the rotary plate 18. Each outlet 28 is generally frustro-conical in cross section at a forward end and communicates at a rearward end with the interior of enclosure 16. Multiple secondary strands 30 are routed from spools 31 within enclosure 16 through the outlets 28 as shown. The spools 31 are spaced apart so that each secondary strand 30 aligns generally with a respective outlet 28. The spools 31 feed each secondary strand 30 into its respective outlet 28 under tension as will be explained.
The cable core 22 and secondary strands 30 are pulled along the longitudinal axis 26 in an axial direction designated by numeral 34. The plate 18 is rotated in a controlled fashion in direction 36 relative to enclosure 16 by a conventional drive mechanism (not shown). The rotation of plate 18 causes co-extensive rotation of the secondary strands 30 extending through plate 18 in the direction 36. Fixedly attached to the forward side of enclosure 16 is a cylindrical projection 38. Projection 38 has a rearward annular flange 40 that affixes to the enclosure 16 by means of mounting bolts 42. At a forward end of the projection 38 is a peripheral annular flange 44. A circumferential array of through-bores 46 are disposed through the annular flange, the location of each bore 46 generally aligning with a corresponding respective bore 28 in the rotary plate 18. Each bore 46 is profiled in longitudinal section to provide frustro-conical leading 45 and trailing 47 portions that funnel a respective secondary strand 30 through the flange 44.
With reference to
Passageway 54 of the mandrel 14 is dimensioned in section to closely admit the cable core component 22 of the finished cable 60 as will be appreciated from
From
Each strand 30 tangentially intersects a respective region A, B, C, D, or E of the forward radiused portion 52 of the mandrel 14. Regions A, B, C, D, and E are spaced about the circumferential periphery of the mandrel end 52 so that the strands 30 will not interfere and become entangled with each other during the winding operation. Each strand 30, upon intersecting the mandrel end 52, follows the radius of curvature of the mandrel end 52 to the forward outlet of mandrel passageway 54 and the cable core 22 exiting therefrom. The multiple secondary strands 30 thus converge upon respective, separated regions of the mandrel end 52 and thereupon follow respective, separated paths along the curvature of mandrel end 52 to converge and meet at the cable core 22.
The strands 30 are wound around the cable core 22 by the rotation of rotary plate 18 as the cable core 22 is axially advanced. The strands 30 follow an optimized approach angle θ (
From the foregoing, it will be appreciated that the mandrel 14 works in conjunction with the strander apparatus 12 to create a wound cable construction of uniform twist and configuration. The mandrel may be fitted at the forward end of the strander and does not interfere with other components. The radiused forward end of the mandrel acts to separate the strands 30 and to keep their approach paths at an optimum, equal approach angle. The mandrel forward radiused end allows the strands 30 to follow the radius surface to meet at the cable core.
With reference to
The invention includes an apparatus and a method for making a wound conductor. The method of manufacture includes: feeding a cable core along a feed path; axially guiding one or more secondary strand(s) from a location offset from the cable core toward the cable core at an approach angle; routing the cable core through a forwardly disposed mandrel body; intersecting a radiused forward end of the mandrel body by the secondary strand(s); routing the secondary strand(s) over the radiused forward end of the mandrel body to an intersection with the cable core; and rotating the secondary strand(s) and the mandrel body about the cable core to create a finished wound conductor. The method may also include imparting an overtwist into the finished wound conductor to rid the finished wound conductor of residual stress forces.
Accordingly, the subject invention accomplishes the achievement of a strander apparatus and method that can maintain an optimal spatial relationship between radially fed secondary wire conductors and an axial conductor core while the conductors are rotated into a wound conductor construction. The strander apparatus and method allows for careful control of the approach angle between the secondary wire conductors and the conductor core and is thus capable of maintaining a desired pitch and twist per lay length of finished product. Moreover, the apparatus and method provides for the elimination of residual twist stresses from the wound wire construction by routing the wound conductor through an overtwist station.
Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.
