Technical Field
[0001] The present invention relates to a backward tension applying mechanism for twisting
paired electric wires at equal pitches without any slack to make a twisted pair cable
that is excel in signal protection against electrical noise, and a method for fabricating
a twisted pair cable by employing the same mechanism.
Background Art
[0002] Conventionally, there have been proposed various fabrication configurations for fabricating
the twisted and paired electric wires (twisted pair cable) by twisting together paired
electric wires. For example, PTL1 describes a twisted pair cable fabrication configuration
in which connectors connected to ends of paired electric wires are fixed to corresponding
receiving jigs, the paired electric wires are respectively inserted into electric
wire insertion grooves in a central driven gear, and the driven gear is rotated by
a drive gear to twist together the paired electric wires.
[0003] In addition, PTL2 describes, as a conventional example, a twisted pair cable fabrication
configuration in which terminals at one ends of paired electric wires are fixed to
a stationary member, while terminals at the other ends are fixed to a rotary member,
and the paired electric wires are twisted together by rotating the rotary member.
As one embodiment, a configuration is described in which paired electric wires are
fed out towards the other end side of the paired electric wires while one end portion
of each of the paired electric wires are twisted respectively within cylindrical portions,
and a rotor at an intermediate portion is fed out towards the other end side while
being rotated in the same direction as the direction of the twisting at the one end
portions so as to twist together the paired electric wires.
[0004] Additionally, PTL3 describes a twisted pair cable fabrication configuration in which
one ends of paired electric wires are respectively fixed to corresponding clamps at
the one end, the other ends of the paired electric wires are respectively connected
to corresponding clamps at the other end, the clamps at the other end are respectively
pulled by corresponding cylinders, and the clamps at both the ends are respectively
rotated in opposite directions by corresponding motors so as to form a twisted pair
cable.
[0005] In addition, PTL4 describes a twisted pair cable fabrication configuration which
employs pairs of electric wires which are different in length. One ends of the pairs
of the electric wires are fixed to a common clamp, while the other ends of the long
electric wire and short electric wire are respectively connected to corresponding
clamps. The clamp for the short electric wire can move forwards and backwards. Then,
the clamps connected to the other ends are rotated by motors to form the pairs of
electric wires which are different in length.
Citation List
Patent Literature
Summary of Invention
Technical Problem
[0007] However, in the prior arts that are described in PTL1 to PTL4, in a case in which
paired electric wires are twisted together as is shown in an example in Figs. 7(a)
and (b), there would be caused the following possibility. In Fig. 7(a), one ends of
paired electric wires 61 are connected together to a common clamp 62, while the other
ends of the paired electric wires 61 are connected to corresponding clamps 63. Then,
the paired electric wires 61 are twisted together by rotating an intermediate rotor
64, for example, in such a state that a backward tension (a tensile force) is applied
to the paired electric wires 61 on the common clamp 62 side. As this occurs, since
there exits variation within a permitted tolerance in length to which the paired electric
wires 61 were cut, the paired electric wires 61 are twisted together with the longer
electric wire 61
1 being slackened slightly, and the variation in length of the paired electric wires
61 is absorbed in a twisted portion as is shown in Fig. 7(b). This deteriorates the
accuracy of pitch at which the electric wires 61 are twisted, and therefore, it has
been unable to ascertain that twisted portions 61a are uniform in condition irrespective
of their positions along the length of a completed twisted pair cable 61'. Because
of this, the quality of the completed twisted pair cable 61' needs to be guaranteed
by measuring an inter-wire gap and characteristic impedance. In Fig. 7(b), reference
numeral 65 denotes a terminal connected to both the ends of the paired electric wires
61.
Solution to Problem
[0008] The present invention has been made in view of the situations that are described
above, and it is an object of this invention to provide a backward tension applying
mechanism for twisting paired electric wires, which can form a twisted pair cable
with good quality which is twisted at uniform pitches without involving any slack
by devising the way to apply backward tension, even in a case in which there exists
variation in length of paired electric wires and a method for fabricating the twisted
pair cable by employing the same mechanism.
[0009] In order to achieve the object, according to a first aspect of the present invention,
there is provided a backward tension applying mechanism for twisting paired electric
wires, according to claim 1.
[0010] According to the configuration, one ends of paired electric wires are connected to
the pair of electric wire clamps, while the other ends of the paired electric wires
are fixed to other electric wire clamps. Then, the pair of air cylinders are actuated,
and the pair of electric wire clamps are caused to move backwards respectively relative
to the common stationary base plate by the pair of movable base plate, whereby the
paired electric wires are pulled respectively relative to the other electric wire
clamps so as to absorb slack therein. Then, in this state, the paired electric wires
are twisted together at equal pitches without involving any slack (looseness).
[0011] According to a second aspect of the present invention, there is provided a method
for fabricating a twisted pair cable, according to claim 2.
[0012] According to the configuration, the one end portions of the paired electric wires
are fixed by the pair of electric wire clamps, and the other end portions of the paired
electric wires are fixed by the other electric wire clamps. Then, the pair of air
cylinders are actuated so that the pair of electric wire clamps caused to move backwards
respectively relative the common stationary base plate by the pair of movable base
plates so as to absorb slack in each of the paired electric wires. Then, in this state,
the paired electric wires are twisted together at equal pitches without involving
any slack (looseness). The twisting of the paired electric wires is implemented, for
example, by rotating the other electric wire clamps by a motor, by turning the paired
electric wires by a rotor between the pair of electric wire clamps and the other electric
wire clamps, or by rotating the other electric wire clamps by the motor, while rotating
the rotor, in the same direction and rotation speed as the rotor. The other electric
wire clamps may be paired up with each other or a common electric wire clamp may be
adopted to fix the other end portions of the paired electric wires.
Advantageous Effects of Invention
[0013] According to the first aspect of the present invention, even though the paired electric
wires have different lengths, the paired electric wires can be twisted together in
such a state that the paired electric wires are stretched tight by absorbing slack
therein by pulling respectively the paired electric wires by the corresponding air
cylinders. By adopting this configuration, even in a case in which there exists variation
in length of paired electric wires, it is possible to form a twisted pair cable with
good quality in which the paired electric wires are twisted together at uniform pitches
without involving any slack.
[0014] According to the second aspect of the present invention, even though the paired electric
wires have different lengths, the paired electric wires can be twisted together in
such a state that the paired electric wires are stretched tight by absorbing slack
therein by pulling respectively the paired electric wires by the corresponding air
cylinders. By adopting this configuration, even in a case in which there exists variation
in length of paired electric wires, it is possible to form a twisted pair cable with
good quality in which the paired electric wires are twisted together at uniform pitches
without involving any slack.
Brief Description of the Drawings
[0015]
Fig. 1 is a perspective view showing an embodiment of a backward tension applying
mechanism according to the present invention.
Fig. 2 is a perspective view showing electric wire clamps of the backward tension
applying mechanism.
Fig. 3 is a perspective view showing a state in which backward tension is applied
to electric wires in the backward tension applying mechanism.
Fig. 4 is a perspective view showing one mode of other electric wire clamps which
are disposed at an opposite side to the side where the backward tension applying mechanism
is disposed.
Fig. 5(a) is a schematic plan view showing one mode of a method for fabricating a
twisted pair cable, and Fig. 5(b) is a schematic plan view showing a completed twisted
pair cable.
Fig. 6 is a perspective view showing one mode of a twisted pair cable-fabrication-apparatus
to which the backward tension applying mechanism is applied.
Fig. 7(a) is a schematic plan view showing one mode of a conventional method for fabricating
the twisted pair cable, and Fig. 7(b) is a schematic plan view showing the completed
twisted pair cable.
Description of Embodiments
[0016] Figs. 1 to 3 show one embodiment of a backward tension applying mechanism for twisting
paired electric wires according to the present invention.
[0017] As shown in Fig. 1, a backward tension applying mechanism 1 for twisting paired electric
wires includes a pair of left and right electric wire clamps 2, a pair of left and
right strip-like movable base plates 3 on which the electric wire clamps 2 are installed
respectively, a rectangular common stationary base plate 5 having a pair of left and
right guide rails 4 with which the movable base plates 3 are respectively brought
into slidable engagement, and a pair of left and right long air cylinders 6 which
are provided at left- and right-hand sides of the common stationary base plate 5 and
of which distal ends of rods 6a are fixed to front ends of the corresponding movable
base plates 3 via corresponding brackets 7.
[0018] The clamps 2, movable base plates 3, rails 4, air cylinders 6 and brackets 7 are
each disposed symmetrically widthwise. Each of the clamps 2 has a horizontal electric
wire insertion groove 9 having a terminating end face (a rear end face) 9a which is
disposed symmetrically widthwise with a terminating end face (a rear end face) 9a
of a horizontal electric wire insertion groove 9 in the other clamp 2 and with which
a distal end 8a of each of a pair of left and right electric wires 8 is brought into
abutment, a block portion 10 in an upper surface of which the electric wire insertion
groove 9 is provided, a cutout portion 10c provided in an external vertical side-wall
10b of the block portion 10 at a front portion of the electric wire insertion groove
9, a vertically elongated movable electric wire holding plate 11 which enters the
cutout portion 10c so as to fixedly hold a distal end portion of the electric wire
8 between an inner surface of a vertical inner wall 10d of the block portion 10 and
itself, a compression coil spring (a spring member) 12 which biases the electric wire
holding plate 11 towards the internal wall 10d of the block portion 10, an operation
lever 13 which can move forwards and backwards and which is formed into an L-shape
at a rear end thereof, and wedge-shaped portions 14 (refer to Fig. 2) which are formed
integrally on a front portion of the operation lever 13 to press the electric wire
holding plate 11 outwards against the biasing force of the coil spring 12 so as to
form a gap which is equal to or larger than a diameter of the electric wire between
the electric wire holding plate 11 and the internal wall 10d of the block portion
10.
[0019] The movable base plates 3 are disposed so as to lie close widthwise to each other,
and the clamps 2 are disposed so as to lie close widthwise to each other. The movable
base plates 3 and the clamps 2 are both separated widthwise from each other with respect
to a central narrow gap 15 as a boundary. The clamp 2 is disposed on a front half
of the corresponding movable base plate 3, and one of a pair of left and right short
air cylinders 16 is disposed on a rear half of the movable base plate 3 concerned.
The pair of air cylinders 16 are designed to automatically release the fixing of the
electric wires by the clamps 2. In a state shown in Fig. 1 in which the electric wires
are fixed (set) in place, distal ends of rods 16a of the short air cylinders 16 are
in abutment with rear end faces 13a of the operation levers 13 which has retreated.
The air cylinders 16 are disposed so as to lie close widthwise to each other and are
separated widthwise from each other with respect to a central gap 17 as a boundary.
[0020] The common stationary base plate 5 is formed wider than a total width of the pair
of left and right movable base plates 3, and the pair of left and right guide rails
4 are disposed so as to extend from a rear end 5a to a position lying further forwards
than a front end 5b of the common stationary base plate 5 by passing the front end
5b (with front end portions of the guide rails 4 so extending denoted by reference
numeral 4a). In addition, sliding engagement portions 18 are provided on respective
rear surfaces of the movable base plates 3 so as to be brought into slidable engagement
with the corresponding guide rails 4. A stopper plate 20 is erected at the rear end
5a of the common stationary base plate 5, and this stopper plate 20 has a pair of
left and right stopper projections 20 with which stopper projections 19 at rear ends
of the movable base plates 3 are brought into abutment.
[0021] Cylinder main bodies 6b, having a hollow cylindrical shape, of the pair of left and
right backward tension applying air cylinders 6 are fixedly disposed at left- and
right-hand sides of a front surface of the common stationary base plate 5 in positions
which lie further outwards widthwise than the pair of movable base plates 3 so as
to extend longitudinally from the rear end to the frontend of the common stationary
base plate 5. The respective rods 6a of the air cylinders 6 project long towards the
front and are then connected respectively to brackets 7 which project widthwise at
respective front ends of the movable base plates 3. In a state shown in Fig. 1 in
which the rods 6a of the air cylinders 6 are extended, no backward tension is applied
to the electric wires 8, and therefore, the electric wires 8 hang down loosely. The
clamps 2 are closed to hold the electric wires 8 side by side widthwise at the same
height.
[0022] Fig. 2 shows a state in which the clamps 2 are each opened. In the state shown in
Fig. 2, when the operator inserts one end portions of the electric wires 8 (See, Fig.
1) into the electric wire insertion grooves 9 in the clamps 2 and pulls the operation
levers 13 backwards, the tapered wedge-shaped portions 14 retreat together with the
operation levers 13, whereby the gaps between the inner walls 10d and the holding
plates 11 in the block portions 10 are narrowed down to a gap equal to or smaller
than the diameter of the electric wire, and the electric wires 8 are fixedly held
between the inner walls 10d and the holding plates 11 by virtue of the biasing forces
of the coil springs 12.
[0023] The respective rods 6a of the air cylinders 6 are retracted into the corresponding
cylinder main bodies 6b by virtue of respective air pressures of the air cylinders
6 as is shown in Fig. 3 from the state shown in Fig. 1, whereby the movable base plates
3 move backwards along the corresponding guide rails 4 together with the corresponding
rods 6a. Then, the clamps 2 move backwards together with the corresponding movable
base plates 3, whereby backward tension is applied respectively to the electric wires
8 by the corresponding clamps 2.
[0024] Even though lengths of the electric wires 8 vary, by applying the backward tension
respectively to the electric wires 8 in the way described above, tensile forces applied
to the electric wires 8 are made uniform (that is, the electric wires 8 are pulled
with equal forces), whereby the generation of slack due to the difference in length
between the electric wires 8 is prevented. Respective plugs 6c of the air cylinders
6 may be connected to a common air pressure hose. In Fig. 3, the respective rods 6a
of the air cylinders 6 are not compressed completely but still project leaving an
extra stroke to some extent, so that backward tension can be applied to an electric
wire 8 which is longer than expected.
[0025] Fig. 3 shows a state in which the electric wires 8 are set at one ends thereof. The
other ends of the electric wires 8 are fixed separately by a pair of left and right
cylindrical electric wire clamps (other electric wire clamps) 21, for example, as
is shown in an example in Fig. 4. The clamps 2 shown in Fig. 4 each include a cylindrical
wall 22, an electric wire insertion groove 23 provided in the cylindrical wall 22
and having an electric wire abutment surface 23a at a terminating end, a holding portion
24 which holds an end portion of the electric wire 8 inserted in the electric wire
insertion groove by virtue of a biasing force of a spring, and an L-shaped operation
lever 25 which lies at right angles to the cylindrical wall and which opens the holding
portion 24 against the biasing force of the spring. The clamps 2 are fixed to a common
rotary plate 26 while lying side by side widthwise, and the rotary plate 26 is connected,
in turn, to a motor 27, whereby the clamps 2 and the rotary plate 26 rotate together
by driving the motor 27. The motor 27 is fixed to a base plate 28 via short strut
29.
[0026] One mode of a method for fabricating a twisted pair cable by employing the backward
tension applying mechanism described above is shown in Fig. 5(a). As shown Fig. 5(a),
front and rear ends of a long electric wire 8
1 and a short electric wire 8
2, which are eventually cut to different lengths which fall within a permitted cutting
tolerance, are fixed in place respectively by the front and rear clamps 2, 21. The
front (or other) clamps 21 are disposed side by side widthwise without being offset
in a front-to-rear direction, whereby the front end positions of the electric wires
8 are regulated equally by the clamps 21. The rear clamps 2 are caused to move slidingly
backwards by the corresponding air cylinders 6 (See Fig. 3), and the rear clamp 2
holding the long electric wire 8
1 and the rear clamp 2 holding the short electric wire 8
2 are positioned so as to be spaced apart in the front-to-rear direction from each
other, with the former rear clamp 2 positioned rearwards and the latter rear clamp
2 positioned forwards, whereby backward tension is applied respectively to the electric
wires 8 which are so fixed to the corresponding rear clamps 2.
[0027] In this state, for example, a rotor 30, which is disposed close to the clamps 2 at
the rear ends of the electric wires 8, is caused to move towards the front clamps
21 at a constant speed while rotating in one direction as is indicated by an arrow.
At the same time, the front clamps 21 are rotated by the motor 27 (See Fig. 4) in
the same direction and at the same speed as the rotor 31. Thus, the paired electric
wires 8 are twisted together between the rear clamps 2 and the rotor 30.
[0028] While twisting the paired electric wires 8, as is shown in Fig. 5(b), the permitted
cutting tolerance between the paired electric wires 8 is absorbed at a non-twisted
portion 8c on the side where the backward tension is loaded to the electric wires
8 (the side of the rear end portions of the electric wires 8). Then, since the long
electric wire 8
1 has an extra longer length L than the short electric wire 8
2 at the end portion, pitches P between twisted portions 8d of the paired electric
wires 8 are made uniform, and therefore, there is completed a twisted pair cable which
is twisted at uniform pitches P and in a neat fashion at every twisted portion 8d.
[0029] Thus, since the performance of a product (a twisted pair cable 8') can be guaranteed
only by measuring pitches P by the operator, the conventionally performed measurement
of inter-wire gap and characteristic impedance is made unnecessary. In Fig. 5(b),
reference numeral 31 denotes a terminal which is electrically connected to the front
and rear ends of the electric wires 8 through press contact.
[0030] In Fig. 3, although the lengths of the electric wires 8 are reduced while the paired
electric wires 8 are being twisted, the value (N) of backward tension being applied
can be controlled by the air pressures of the backward tension applying air cylinders
6 by regulating (controlling) the air pressures of the air cylinders 6 by an air regulator.
The rods 6a of the air cylinders 6 do not extend, and the value of backward tension
is regulated by the air pressures. Air pressures are applied to the air cylinders
6 so as to realize a value of backward tension which is predetermined depending upon
the diameter or type of electric wires used, and the regulation is completed when
a prescribed air pressure is reached.
[0031] After the paired electric wires 8 are twisted as desired, the rods 6a of the air
cylinders 6 are extended longest as is shown in Fig. 1, and the holding of the electric
wires by the clamps 2 is released as is shown in Fig. 2, whereby the twisted pair
cable 8' can be removed from the clamps 2. The clamps 2 can automatically be released
by extending the short air cylinders 16 shown in Fig. 1 so as to move the operation
levers 13 to the front.
[0032] Fig. 6 shows an example of a twisted pair cable fabrication apparatus 32 to which
the backward tension applying mechanism described above is applied.
[0033] The backward tension applying mechanism 1 is provided equally on each of three circumferential
surfaces of one (rear) intermittent rotary member 33 which are provided circumferentially
at equal intervals. In Fig. 6, reference numeral 2 denotes an electric wire clamp,
reference numeral 16 denotes a clamp releasing cylinder, reference numeral 6 denotes
a backward tension applying cylinder, reference numeral 3 denotes a movable base plate,
and reference numeral 5 denotes a common stationary base plate. The three circumferential
surfaces are made up of three common stationary base plates 5.
[0034] A pair of electric wire clamps (other electric wire clamps) 21 and a common motor
27, which are like those shown in Fig. 4, are provided equally on three circumferential
surfaces of the other (front) intermittent rotary member 34 which are disposed circumferentially
at equal intervals. The three circumferential surfaces are made up of three base plates
28 which are like that shown in Fig. 4. The intermittent rotary members 33, 34 are
supported rotatably on corresponding struts 35, 36 and are rotated together through
one thirds the full rotation at a time by an intermittent driving device (for example,
an air cylinder 37 and a torque brake 38). In each of the intermittent rotary members
33, 34, the circumferential surface situated on a near side refers to an electric
wires setting plane 5, 28, the circumferential surface situated to face downwards
refers to a paired electric wires twisting plane 5
2, 28
2, and the circumferential surface situated on a far side refers to a twisted pair
cable discharge plane 5
3, 28
3.
[0035] Paired electric wires 8 (See Figs. 3, 4) are fixed in place by the front and rear
clamps 2, 21 on the circumferential surfaces at the electric wires setting planes
5, 28, and backward tension is applied to the paired electric wires 8 by the horizontal
cylinders 6. Then, when the circumferential surface rotates to the paired electric
wires twisting planes 5
2, 28
2, a rotor 30, which is cut to be opened in part of a circumference thereof so as to
have a cutout opening portion 30a and which has a twisting rod 30b erected to face
the cutout opening portion 30a as is shown in Fig. 5(a), is raised by a vertical air
cylinder (not shown) so as to be set between the paired electric wires 8 (or the paired
electric wires 8 are inserted through the annular rotor 30). Then, the paired electric
wires 8 are twisted together by rotating the rotor 30 and the motor 27 simultaneously.
Then, when the circumferential surface rotates to the twisted pair cable discharge
plane 5
3, 28
3, tapes are automatically wound around both front and rear ends of a twisted pair
cable 8' (See Fig. 5(b)), and a completed twisted pair cable is discharged. This cycle
is automatically repeated to thereby fabricate twisted pair cables 8' with good efficiency.
[0036] While the embodiment is described as employing the rotor 30, a configuration employing
no rotor 30 may be adopted in which the clamps 21 shown in Fig. 4 are rotated by the
motor 27 in such a state that one ends of the paired electric wires 8 are fixed in
place by the clamps 2 shown in Fig. 3, while the other ends of the paired electric
wires 8 are fixed in place by the clamps 21 shown in Fig. 4, whereby the paired electric
wires 8 can be twisted between the clamps 2 and the clamps 21. The clamps 21 shown
in Fig. 4 refer to an example of holding the paired electric wires 8, and therefore,
any shapes or configurations can be set as required, provided that they can fixedly
hold the paired electric wires 8' respectively and can be rotated by the motor 27.
[0037] In addition, the clamp assembly made up of the clamps 2, the cylinders 6, 16 and
the base plates 3, 5, which are shown in Fig. 3, that is, the backward tension applying
mechanism 1 can be rotated by a motor (not shown). In this case, the clamps 21 shown
in Fig. 4 can be made into a common clamp which clamps the electric wires 8 altogether.
In addition, the paired electric wires 8 can be twisted together between the front
and rear clamps 2, 21 by rotating the intermediate rotor 30 only without using the
motor 27 on the clamp side. Additionally, the clamps 3 shown in Fig. 3 refer to an
example of holding the paired electric wires 8, and therefore, any shapes or configurations
can be set as required, provided that they can fixedly hold the paired electric wires
8 respectively.
[0038] In addition, in Fig. 1, the cylinder main bodies 6b of the backward tension applying
air cylinders 6 can be connected to front ends of the movable base plates 3, and the
rods 6a of the air cylinders 6 can be connected to rear ends of the common stationary
base plate 5. In short, the air cylinders 6 may only have to connect the movable base
plates 3 with the common stationary base plate 5.
Industrial Applicability
[0039] The backward tension applying mechanism and the twisted pair cable fabrication method
which employs the same mechanism can be applied to increase the performance of a twisted
pair cable which is applied to a noise prevention signal wire etc. for motor vehicles
by forming twisted portions at equal intervals without involving any slack (looseness)
therein.
Reference Sign List
[0041]
1 backward tension applying mechanism
2 electric wire clamp
3 movable base plate
4 guide rail
5 common stationary base plate
6 air cylinder
8 electric wire
21 other electric wire clamp