U.S. patent number RE28,961 [Application Number 05/623,220] was granted by the patent office on 1976-09-14 for method and apparatus for manufacturing soft metal sheaths for electrical wires.
This patent grant is currently assigned to Sumitomo Electric Industries, Ltd.. Invention is credited to Mahito Ishikawa, Hiroyuki Kumamaru, Koichiro Matsuno, Akiyoshi Tsukamoto.
United States Patent |
RE28,961 |
Tsukamoto , et al. |
September 14, 1976 |
Method and apparatus for manufacturing soft metal sheaths for
electrical wires
Abstract
Manufacturing of a soft metal sheath formed of aluminum or
copper, for example, is improved by suitably selecting the
apparatus composing the shaping means employed therein and
arranging the capstan and the sinking die in a novel manner. The
apparatus selected is made from a wear-resistant synthetic resin
such as a molybdenum bisulfide-included nylon. The sheath is
manufactured from a metal tape of aluminum or copper through the
working stages of applying a cylindrical tube shaped from the tape
onto a cable core, butt welding the seam, and then reducing the
diameter of the metal tube to connect it to the core.
Inventors: |
Tsukamoto; Akiyoshi (Yokohama,
JA), Kumamaru; Hiroyuki (Yokohama, JA),
Matsuno; Koichiro (Yokohama, JA), Ishikawa;
Mahito (Yokohama, JA) |
Assignee: |
Sumitomo Electric Industries,
Ltd. (Osaka, JA)
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Family
ID: |
27285041 |
Appl.
No.: |
05/623,220 |
Filed: |
October 17, 1975 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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128297 |
Mar 26, 1971 |
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Reissue of: |
374151 |
Jun 27, 1973 |
03874076 |
Apr 1, 1975 |
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Foreign Application Priority Data
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Mar 26, 1970 [JA] |
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45-25497 |
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Current U.S.
Class: |
29/828; 72/343;
156/54; 228/130; 29/728; 156/50; 228/129; 228/131 |
Current CPC
Class: |
H01B
13/2633 (20130101); Y10T 29/53126 (20150115); Y10T
29/49123 (20150115) |
Current International
Class: |
H01B
13/26 (20060101); H01B 13/22 (20060101); H01B
013/22 () |
Field of
Search: |
;29/23C,624,202.5
;156/47,50,51,52,53,54 ;72/258,262,284,343,367,366
;228/135,129,130,131,141,144,146,147,148,149,150,156 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Lanham; C.W.
Assistant Examiner: Duzan; James R.
Attorney, Agent or Firm: Sughrue, Rothwell, Mion, Zinn and
Macpeak
Parent Case Text
This is a continuation of application Ser. No. 128,297, filed Mar.
26, 1971, and now abandoned.
Claims
We claim:
1. In a method of continuously manufacturing a soft metal sheath
electric cable by moving a soft metal tape longitudinally in unison
with a core and wrapping said tape about said core, the improvement
comprising the steps of, in sequence:
surface cleaning said soft metal tape whose width is in excess of
that needed to laterally envelope the cable core,
cutting off both side edges of said tape to reduce the width of
said tape to a dimension such that the side edges will exactly abut
when laterally wrapped about the core and to provide abutting side
edges which are oxide free,
bending said tape into an arc in cross section by passing said tape
through opposed concave and convex wear resistant plastic
rollers,
butting said oxide free tape side edges together by passing said
arc-shaped tape through a wear resistant plastic cylindrical
shaping tool and a wear resistant plastic forming die having a
circular opening therein,
seam welding the butting oxide free side edges,
extracting the tube from said forming die and pushing the tube
through a reducing die under lubrication by means of a capstan
positioned upstream of the reducing die and downstream of the
forming die to uniformly radially inwardly reduce the tube to
mechanically couple the soft metal tube to the outer surface of the
cable core with true circular cross section provided thereby.
Description
BACKGROUND OF THE INVENTION
This invention relates to the improvement of the method and
apparatus for manufacturing soft metal sheaths for electrical cable
wherein a soft metal tape such as aluminum tape or copper tape
formed to a cylindrical tubular shape is applied on the periphery
of an insulated core for the electrical cable; the butted edges are
welded, e.g., by inert gas arc welding; the outer diameter of thus
obtained metal tube is reduced; and the insulating core and metal
tube are adhered to each other.
Methods are known for forming metal tape in the manufacturing of
soft metal sheaths for an electrical cable. In one method, the tape
is gradually shaped to a cylindrical form by passing it through a
plurality of rollers. In a second method, the tape is arranged in
the longitudinal direction and the lateral end portions or ears are
formed to a cylindrical shape by means of a metallic forming tool
like a shape of a cut open circular tubular pipe. It has been
generally found, however, that friction and burning are caused
between the tape and the tool, the tension force increased and
undesirable faults are generated on the surface of the tape when
forming such a soft metal tape by use of a forming tool of steel,
particularly in the case of aluminum.
Next, as methods for welding the thus formed seam, the methods of
high frequency induction heating or inert gas arc welding are well
known. And further, as a method for metal sheathing the periphery
of the finished insulated core, the processing by forming a metal
tape to a cylindrical tubular shape and continuously welding the
butted edges in the longitudinal direction is also known.
However, it is required in the known methods, as mentioned above,
to make the inner diameter of the metal tube larger than the outer
diameter of the insulated core so as to be able to provide an
aperture for thermal insulation between the insulated core and the
seam welding portion of the metal tube in order to prevent the
melting of the insulated core by heating during the welding
operation. Therefore, a working stage is necessary to join the
periphery of the insulating core and the inner face of the metal
tube to each other after welding.
In the prior methods of manufacture, the metal tube 20 has been
reduced by drawing it through a sinking die 16 as shown in FIG. 7.
This has caused problems, such as retaining of the lubricating oil
supplied onto the metal 20 from a supplying device 15 to lubricate
the inner surface of the die 16, causing slipping relative to the
traction of the capstan 13 being the extracting means, causing
variation in the drawing velocity and encountering troubles on the
welding in the previous working stage. It has also been considered
to provide a cleaning means to remove such oil, but this would
require a very expensive installation and greatly increased
manufacturing costs.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for
manufacturing such soft metal sheaths for electrical wires so as to
completely remove the faults caused by the prior methods as
mentioned above, by the combination of simple devices and
characterized by the two features of selecting the material for the
tool for forming the cylindrical tube and arranging of the capstan
and the sinking die in a novel manner.
BRIEF DESCRIPTION OF THE DRAWINGS
The details of the present invention will be clear in accordance
with description of embodiments of this invention in reference to
the accompanying drawings.
In the drawings:
FIG. 1 is a schematic view of the apparatus for practicing the
method of the invention;
FIGS. 2 through 6 are the auxiliary elevational views, partly in
section, of parts of the apparatus; and
FIG. 7 is a schematic view of a prior art manufacturing method.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIG. 1, a soft metal tape 1, for example, a soft
aluminum tape, is passed through a cleaning device 3 to remove any
oil or dirt on the surface of the tape and the cleaned cross
section is exposed by slightly cutting off both lateral edges of
the soft metal tape by means of a cutting machine 4. Cutting off
both lateral edges of the tape permits welding of the edges which
are not contaminated by a metallic oxide and at the same time
provides a tape width which is of an exact desired dimension to
achieve butting of the side edges during welding. The scrap winder
5 serves to coil up the soft metal tape thus cut off. Then, the
tape is shaped to an arc by use of an arc shaping device made of a
wear-resistant synthetic resin, for example, a molybdenum
bisulfide-included nylon, such as the rollers 6 and 7. The front
view of the rollers 6 and 6' is shown in FIG. 2. Thereafter, the
tape is shaped to a cylindrical form by means of a shaping tool 8
and simultaneously the insulated core 2 is inserted thereinto.
The shaping tool 8 is provided with a conical introducing opening
composed of a suitable wear-resistant synthetic resin, for example,
a molybdenum bisulfide-included nylon, and the tape passing through
the opening is shaped to a cylindrical shape by a drawing
operation. FIG. 3a is a plan view of the shaping tool 8 and FIG. 3b
shows partially the feature of the processing of the shaping and
the mounting of the tape 1 onto the periphery of the insulated core
2 by the tool 8, wherein the cross sectional views of a, b and c
respectively correspond to the points of a, b and c in the drawing
of FIG. 3a. Numeral 9 shows a forming die composed of a suitable
wear-resistant synthetic resin, and the tape 1 forms a cylindrical
tube in a complete butted state with a suitable gas between the
seam of the tape and the insulating core 2. This condition is shown
by c in the drawing of FIG. 3b.
The butted portion of the seam at the both edges of the tape 1
formed to a cylindrical shape is repressed by the repressing
rollers 10 as shown in FIG. 4 so as not to cause a step. And the
complete butted condition is maintained by the side rollers 12 as
shown in FIG. 5. The butted portion of the cylindrical tube
maintained under such condition is seam welded with the electrode
11 of the inert gas arc welding machine.
Next, the metal tube 20 comprising the insulated core is pulled by
means of a capstan as shown by 13 in FIG. 6. To prevent the soft
metal tube from buckling, it is passed through a guide 14 provided
with a circular introducing opening mounted on the outlet of the
capstan 14. 16 shows the sinking die which reduces the diameter of
the metal tube by pushing inwardly such that the outer surface of
the insulated core and the inner surface of the metal tube are in
close relation to each other.
Prior to entering into the sinking die 16, a lubricating oil is
dropped on the metal tube from a nozzle of an oil supplying means
as shown by 15 to make the reducing operation smooth.
By the method of the present invention, the cylindrical metal tube
can be readily obtained without causing defects on the surface of
the soft metal tape by simply combining forming tools of a
wear-resistant synthetic resin and the soft metal sheathed cable,
in which the mechanical strength is guaranteed, and by combining
suitable welding methods such as the inert gas arc welding method.
By changing the pulling-out method to the pushing-in method in
reducing the diameter of the metal tube, a slip between the capstan
and the soft metal tube brought about by the lubricating oil is
eliminated and a stable extracting linear velocity can be
established, thereby obtaining a stable welding workability.
And further, a cleaning means for removing the lubricating oil
retained on the tube becomes unnecessary, and it is greatly
advantageous for reducing the manufacturing cost.
And furthermore, by this pushing-in method, a high quality product,
extremely high in roundness, can be obtained by a final reduction
of the diameter of the soft metal tube after extracting the soft
metal tube comprising the insulated core by means of the capstan.
In contrast to that, by the prior art method shown in FIG. 7, the
soft metal tube tends to deform to an elliptic shape as the tube is
clamped with a capstan and pulled after final working for the
reducing of the diameter.
As described above, in accordance with the method and apparatus of
the present invention, the adjustment of the manufacturing
apparatus is very easy and the method has great advantages over the
prior method from the standpoint of quality of the product and the
installing cost.
While the preferred form of method and apparatus embodying the
invention is illustrated and described, it will be understood that
changes in the method and apparatus may be made within the scope of
the appended claims.
* * * * *