JPH0669252B2 - Core wire flaw detection method and detection head used in this method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a core wire flaw detection method for detecting flaws imparted to a core wire during a wire cutting / leading step, and a detection head used in this method.

"Prior Art" FIG. 14 is a schematic configuration diagram showing an example of a core wire flaw detection device using a conventional core wire flaw detection method in an electric wire lead-out step.

In this figure, 1 is an electric wire, and 2 and 2 are lead-out cutters that cut and remove the insulating coating of the electric wire 1, respectively, and are arranged to face each other with their cutting edges facing the electric wire 1. In this case, each of the output cutters 2 and 2 is adapted to move in the vertical direction in the drawing by a drive unit (not shown). 3 is an AC power supply, one output end of which is an output cutter 2,
2 are connected to each other, and the other output end is the input end T of the detector 4.
connected to a. The detector 4 detects a voltage, and its input end Tb is connected to the electrode 5. The electrode 5 is formed in a tubular shape so as to cover the periphery of the electric wire 1. Here, FIG. 15 is a cross-sectional view of the electrode 5 taken along the line I-I, and as shown in this figure, the electric wire 1 is arranged with the axis center in common with the electrode 5.

In the core wire flaw detection device configured as described above, first,
The electric wire 1 is passed through the inside of the electrode 5 and arranged at a predetermined place.
Then, a power switch (not shown) inserted in the circuit is turned on. As a result, the output cutters 2 and 2 are connected to the electric wire 1.
Move towards and cut the insulation coating. Then, after the insulating coating is cut, the electric wire 1 is pulled in the left direction of the drawing, and the cut insulating coating is removed. Here, for example, when the lead-out cutters 2 and 2 contact the core wire 1a when the coating is cut, the capacitance between the wire 1 and the electrode 5 via this-the detector 4-the path of the AC power supply 3 AC current flows,
A voltage corresponding to this current is detected by the detector 4. As a result, it is detected that the lead-out cutters 2, 2 have come into contact with the core wire 1a. The lead cutters 2 and 2 are core wires 1.
Even if it does not come into contact with a, a small amount of current will flow in the circuit due to the stray capacitance generated between them, and the electrode 5
Although a slight voltage is generated between and, this voltage is ignored in the above description.

Next, FIG. 16 is a schematic configuration diagram showing another example of the core wire flaw detection device using the above-described conventional core wire flaw detection method. In this figure, the same parts as those in FIG. 14 described above are designated by the same reference numerals, and the description thereof will be omitted.

An electrode 5a is arranged at a distance d from the lead-out cutters 2 and 2. Here, FIG. 17 is a view of the electrode 5a shown in FIG. 16 seen from the direction of arrow A, and FIG. 18 is a side view of the electrode 5a. In FIG. 18, 6 is a hollow electrode main body formed in a rectangular shape, and a tapered through hole 7 penetrating from the right side to the left side of the drawing is formed.
In this case, the inner peripheral surface (hereinafter referred to as the guide surface) 7 of the through hole 7
By inserting the electric wire 1 in the direction of arrow B along a,
The electric wire 1 can be arranged at a predetermined place.
That is, by providing the tapered through hole 7, the electric wire 1 can be guided and positioned. next,
Reference numeral 8 denotes a mounting flange for fixing the electrode body 6, which is formed on the lower portion of the body 6. A BNC type connector 9 is attached to the upper surface of the electrode body 6.

[Problems to be Solved by the Invention] By the way, when the above-mentioned conventional core wire flaw detection method is applied to the wire cutting / leading step, as shown in FIG. Cutter 11,
Since 11 and 11 are held by the conductive cassettes 12 and 12, they are electrically connected to each other and the flaw of the core wire 1a cannot be detected. That is, each of the output cutters 2 and 2 cuts the insulating coating of the electric wire 1 and at the same time, the cutting cutter 1
This is because, because the core wires 1 and 11 cut the core wire 1a, the magnitude of the current flowing through the circuit becomes substantially constant regardless of whether the lead-out cutters 2 and 2 contact the core wire 1a.

On the other hand, in the above-mentioned conventional electrode 5a, in order to satisfy the function of guiding and positioning the electric wire 1, the distance d between the lead-out cutters 2 and 2 must be shortened. Therefore, the capacitance between the output cutters 2 and 2 and the electrode 5a becomes relatively large. Therefore, even when the lead-out cutters 2 and 2 do not come into contact with the core wire 1a in a normal state, the AC power supply 3-lead-out cutters 2 and 2
-Electrode 5a-Detector 4-AC power supply 3 when the value of the current flowing in the path of AC power supply 3 becomes relatively large and abnormal
The difference from the value of the current flowing through the path of the output cutter 2, 2-core wire 1a-electrode 5a-AC power supply 3 becomes small. In this way, the difference in the current flowing in the circuit between the normal state and the abnormal state is small, so that the detection sensitivity is reduced.

The present invention has been made in view of the above circumstances, and a core wire flaw detection method capable of detecting the presence or absence of a scratch given to the core wire of a lead cutter in a wire cutting / leading step and performing the detection with high sensitivity. And to provide a detection head for use in this method.

[Means for Solving the Problem] The invention according to claim 1 is a step of cutting and tapping an electric wire by each of a cutting cutter and a tapping cutter arranged at a predetermined interval on a holding member having conductivity. Applied to the surface of the electric wire, and then applying an AC power supply between the electrode and the lead-out cutter, the voltage value between the AC power supply and the electrode by the detection means. In the core wire flaw detection method of detecting whether or not the lead-out cutter has contacted the core wire of the electric wire by measuring, the cutting cutter and the lead-out cutter, the capacitance between the electrode and the core wire of the electric wire It is characterized in that insulation is performed via an insulator having an electrostatic capacitance obtained based on the relationship between the detection sensitivity of the detection means and the detection sensitivity of the detection means.

The invention according to claim 2 is a detection head constituting an electrode used in the core wire flaw detection method according to claim 1, wherein a bell-shaped guide surface is formed on a side into which the electric wire is inserted. It is characterized by comprising a hollow insulating member and an electrode which is arranged inside the insulating member so as to face the electric wire and which is connected to the detecting means.

[Operation] According to the invention described in claim 1, even if the cutting cutter comes into contact with the core wire of the electric wire, almost no current flows through the detecting means through the lead-out cutter. On the other hand, when the lead-out cutter contacts the core wire, a large current flows through the detection means. As a result, the presence or absence of scratches on the core wire of the lead-out cutter can be detected with high sensitivity and without error.

In addition, the capacitance between the electric wire and the core wire and the detection sensitivity of the detection means can be used to determine the electrostatic capacitance between the cutting cutter and the output cutter, which is necessary to insulate the cutting cutter from the lead wire cutter. The thickness, thickness, etc. can be optimally selected according to the detection sensitivity.

Further, according to the second aspect of the present invention, since the electrode is arranged inside the insulating member, the detection sensitivity does not decrease even when the lead-out cutter approaches the electrode. Further, the electric wire can be easily inserted into the hollow portion from the bell-shaped guide surface of the insulating member, and the gap between the electrode arranged inside the insulating member and the electric wire inserted in the hollow portion can be reduced. can do.

[Examples] Examples of the present invention will be described below with reference to the drawings. In this description, first, the core wire flaw detection method is performed, and then, the detection head of the core wire flaw detection apparatus using this method is performed.

(I) FIG. 1 shows the cutting of an electric wire according to an embodiment of the present invention.
It is a schematic block diagram which shows an example of the core wire flaw detection apparatus to which the core wire flaw detection method for detecting the flaw given to the core wire by the lead-out cutter in the lead-out step is applied. In this figure, parts common to those in each of FIGS. 14 and 19 described above are designated by the same reference numerals, and the description thereof will be omitted.

In this figure, 14 and 14 are lead cutters 2 and 2, respectively.
2 is an insulator that electrically insulates the cutting cutters 11 and 11 from each other, and is attached in a gap formed on the cassette 12, 12 side between the cutting cutters 11 and 11 and the cassettes 12 and 12 as illustrated. Has been. In this case, the cutting cutters 11, 11 are movable in the vertical direction in the drawing with respect to the insulators 14, 14.

In this way, the output cutters 2, 2 and the cutting cutter 11,
By electrically insulating 11 and 11 by the insulators 14 and 14, even when the cutting cutters 11 and 11 come into contact with the core wire 1a at the time of cutting and tapping the electric wire 1, a circuit is provided via these cutting cutters 11 and 11. Only a very small current flows through. On the contrary, when the lead-out cutters 2 and 2 come into contact with the core wire 1a, a large current flows in the circuit through the lead-out cutters 2 and 2. Therefore, the value of the current flowing in the circuit is greatly different between when the lead-out cutters 2 and 2 come into contact with the core wire 1a and when it does not. be able to.

Next, a method for determining the material and dimensions of the above-mentioned insulators 14, 14 will be described. Here, in FIG. 1, the electrostatic capacitance between the electrode 5 and the core wire 1a is C ₁ , and the electrostatic capacitance between the output cutters 2 and 2 and the cutting cutters 11 and 11 is C ₂ . Further, the detector 4 is replaced with a resistor R, and the potential difference across the resistor R is V. Further, the output voltage of the AC power supply 3 is set to Vo.

Now, an equivalent circuit of the core wire flaw detector in a normal case where the lead-out cutters 2 and 2 do not contact the core wire 1a is as shown in FIG. In this case, in FIG. 1, there is a capacitance C ₃ between the lead-out cutters 2 and 2 and the core wire 1a, but the lead-out cutters 2 and 2 are closer to each other than the facing surface between the lead-out cutters 2 and 2 and the core wire 1a. Since the surface facing the cutting cutters 11 and 11 is much wider, the electrostatic capacitance C ₃ << electrostatic capacitance C _{2 is obtained} , and the electrostatic capacitance C ₃ can be ignored.

On the other hand, the equivalent circuit of the device in the case where the lead-out cutters 2 and 2 are abnormal in contact with the core wire 1a is as shown in FIG.

Here, the potential difference between both ends of the resistor R in the normal case is In case of abnormality, the potential difference across the resistor R Then, these potential differences The absolute value of is expressed by the following equation. Note that ω (= 2π) is the angular frequency of the AC power supply 3.

From equations (1) and (2), voltage And voltage And the ratio is Becomes In this case, the expression (3) is the ratio of the voltage at the time of abnormality to the voltage at the time of normality, and can be said to be the sensitivity of the detector 4.

Here, FIG. 4 shows the length l of the electrode 5 in the case of abnormality.
Voltage when changing Is a plot of. In this case, the frequency of the AC power supply 3 is 100 KHz, 200 KHz, 500 KHz, 1
Plotted for MHz and 2 MHz, respectively.
In addition, R shown in FIG. 3 is 1 KΩ, Was set to 5V.

By the way, C ₁ shown in the equivalent circuit shown in FIG. 3 can be obtained by the following equation.

However, Is.

When C ₁ is obtained from the above equation (4) and the result of FIG. 4, it becomes as shown in FIG. In this case, C ₁ is the equivalent capacitance between the electrode 5 and the core wire 1a obtained experimentally. From the results shown in the figure, the longer the length 1 of the electrode 5 and the frequency of the AC power supply 3 are. It can be seen that the lower the f, the greater the equivalent capacitance C ₁ .

From Fig. 5, when setting = 200KHz and l = 50mm, C ₁ is about 5.6 × 10 ^-12 F (farad), so C ₁ × R × ω = 5.6 × 10 ^-12 × 1000 × 2π × 200 x 10 ³ = 7.
It becomes 0 × 10 ^-3 .

When substituting 7.0 × 10 ⁻³ of this value into the equation (3), C ₁ × R ×
Considering that ω << 1, Equation (3) can be approximated by the following equation.

From the above formula, the sensitivity of detector 4 It can be seen that the larger the C ₁ / C ₂ ratio, the larger. Also, the sensitivity of the detector 4 When, be determined capacitances C ₁ between the electrode 5 and the core 1a, it is possible to determine the capacitance C ₂ between the lead-out cutter 2,2 and the cutting cutter 11, 11. That is, now, the sensitivity of the detector 4 If set to, (5) and by a ^{_{C 1 = 5.6 × 10 -12 F}} , to obtain the ^{_{C 2 = C 1 /2=5.6×10 -12 /2=2.8×10}} -12 F and _{C 2} You can

On the other hand, FIG. 7 shows the equivalent capacitance of the tape Tp made of the Teflon (trade name, the same applies hereinafter) resin shown in FIG. With this result,
If a Teflon resin tape with a thickness of 1.7 mm from the above C ₂ = 2.8 × 10 ^-12 F is used, the sensitivity of the detector 4 It can be seen that

In the above embodiment, the insulators 14 and 14 were attached between the cutting cutters 11 and 11 and the cassettes 12 and 12.
2 may be attached between the cassettes 12 and 12. In addition to attaching the insulators 14 and 14, the cutting cutters 11 and 11 may be made of an insulating member such as ceramic.

Further, although the cylindrical electrode 5 is used in the above embodiment,
The shape is not limited to this, and may be, for example, a shape that partially surrounds the electric wire 1 or a shape in which conductive fibers are combined.

(II) Next, FIG. 8 is a plan view showing a detection head DH used in a core wire flaw detection apparatus using a core wire flaw detection method according to an embodiment of the present invention, and FIG. 9 is a front view of FIG. , Tenth
The figure is a sectional view taken along line II-II in FIG.

In these figures, 20 and 21 are blocks each having a rectangular shape and having an insulating property. Among them, the block 20 is, as shown in FIG. 10, a bell mouth from its left end face to the inner center part. A guide surface 20a having a rectangular shape is formed, and further, a hollow portion 20b having a rectangular shape is formed from the center portion inside to the right end surface. In this case, the hollow portion 20b can be formed in parallel from the outlet side (opening end on the left side of the drawing) of the guide surface 20a by forming the guide surface 20a in the shape of a bell. On the other hand, as shown in FIG. 10, the block 21 has a hollow portion 21a having the same diameter as the hollow portion 20b of the block 20 formed between the left end face and the front end of the right end face, and the right end face thereof. Through hole 21b that allows the electric wire 1 to be inserted from the front side to the right end surface
Has been opened. These blocks 20 and 21
Are fixed by bolts 22, 22 ... An electrode 23 is inserted into the hollow portion 20b of the block 20 and the hollow portion 21a of the block 21, and is formed in a rectangular cylindrical shape. Reference numeral 24 shown in FIG. 8 or FIG. 9 is a BNC type connector, which is fixed to the upper surfaces of the blocks 20 and 21 by bolts 25, 25, .... In addition,
The above-described electrode 23 and the signal end (not shown) of the connector 24 are connected by an electric wire (not shown).

When the detection head DH configured as described above is applied to the core wire flaw detection apparatus shown in FIG. 1 described above, it becomes as shown in FIG. In this figure, the electrodes 23 are arranged in the blocks 20 and 21 even if the distance d between the detection head DH and the output cutters 2 and 2 is short, so that the output cutters 2 and 2 do not contact the core wire 1a normally. In this case, it is possible to reduce the value of the current flowing through the path of the AC power supply 3-output cutter 2, 2-electrode 23-detector 4-AC power supply 3.

On the other hand, a guide surface 20a for guiding the electric wire 1 of the detection head DH
Is formed in the shape of a bell, it becomes easy to insert the electric wire 1 into the head DH. Further, by forming the guide surface 20a in the shape of a bell, it is possible to form the hollow portions 20b and 21a in parallel with the end of the guide surface 20a on the outlet side, and the gap between the electric wire 1 and the electrode 23 is formed. Can be narrowed. As a result, the capacitance between the electric wire 1 and the electrode 23 becomes large, and in the case of an abnormality in which the lead-out cutters 2, 2 come into contact with the core wire 1a, the AC power supply 3-lead-out cutter 2, 2-core wire 1a-electrode 23 -Detector 4-The value of the current flowing through the path of the AC power supply 3 can be increased.

Here, FIG. 12 shows when the distance between the detection heads DH and the conventional electrodes 5a is changed when the distance between the output cutters 2 and 2 is normal when the output cutters 2 and 2 do not contact the core wire 1a. 6 is a plot of voltage levels detected by the device 4. The voltage level in the normal case shown in this figure can be said to be noise relating to core wire flaw detection. The smaller this noise is, the better the performance of the detection device is, and as is clear from this figure, the noise of the detection head DH is the electrode. It can be seen that it is smaller than that of 5a.

Further, FIG. 13 shows the ratio of the voltage level detected by the detector 4 when the detection head DH and the conventional electrode 5a are abnormal to the normal when the frequency f of the AC power supply 3 is 100 KH to 2 MHz. It is plotted while changing the interval. As is clear from this figure, 100 kHz
It can be seen that, over the frequency band of 1 MHz, the sensitivity of the detection head DH is better than that of the conventional electrode 5a.

"Effect of the invention" As described above, according to the invention of claim 1, since the cutting cutter and the lead-out cutter are electrically insulated from each other, the presence or absence of scratches on the core wire of the lead-out cutter is highly sensitive and error-free. Can be detected.

In addition, the capacitance between the electric wire and the core wire and the detection sensitivity of the detection means can be used to determine the electrostatic capacitance between the cutting cutter and the output cutter, which is necessary to insulate the cutting cutter from the lead wire cutter. The thickness, thickness, etc. can be optimally selected according to the detection sensitivity. As a result, it is not necessary to make the insulator unnecessarily thick, or to use an insulator made of a material that is more expensive than necessary, so that the cost can be reduced.

According to the second aspect of the invention, since the electrode is arranged inside the insulating member, it is possible to prevent the detection sensitivity from being lowered when the lead-out cutter approaches the electrode.

Further, the electric wire can be easily inserted into the detection head.

Furthermore, since the gap between the electrode and the electric wire can be reduced, the detection sensitivity can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a core wire flaw detection apparatus using a core wire flaw detection method according to an embodiment of the present invention, and FIGS. 2 and 3 are diagrams showing an equivalent circuit of the equipment, and FIG. , Fifth
FIG. 6, FIG. 6 and FIG. 7 are diagrams showing electrical characteristics of the apparatus, FIG. 8 is a plan view showing a detection head, FIG. 9 is a front view of the same head, and FIG. II-II line sectional view, FIG. 11 is a schematic configuration diagram in which the detection head is used in the core wire flaw detection device, and FIGS. 12 and 13 are diagrams showing electric characteristics of the detection head, respectively. Is a schematic configuration diagram showing a core wire flaw detection device using a conventional core wire flaw detection method,
5 is a cross-sectional view taken along the line I-I of FIG. 14, FIG. 16 is a schematic configuration diagram showing another core wire flaw detection device using a conventional core wire flaw detection method, and FIG. 17 is a core wire flaw shown in FIG. FIG. 18 is a side view of the head as seen from the direction of arrow A of the detection head applied to the detection device. FIG. 19 is a diagram for explaining the problems of the conventional core wire flaw detection method. 1 ... Electric wire, 1a ... Core wire, 2, 2 ... Output cutter, 3 ... AC power supply, 4 ... Detector (3, 4 constitutes detection means), 5, 23 ... Electrode, 11, 11 ... Cutting cutter, 12, 12, ... Cassette (holding member), 14,
14 ... Insulator, 20, 21 ... Insulation member (guide surface 20a is formed on 20, and 20, 21, 23 are detection heads D
Compose H).

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kimitaka Ishida 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (56) Reference JP-A-55-26026 (JP, A) JP-A-SHO 56-46609 (JP, A) JP 59-222010 (JP, A) JP 59-230411 (JP, A) JP 2-133016 (JP, A)

Claims (2)

[Claims] 1. An electric wire (1) is cut by a cutting cutter (11, 11) and a lead-out cutter (2, 2) which are arranged on a holding member (12, 12) having conductivity at a predetermined interval. -Applied to the process of lead out, arrange the electrode (5) on the surface of the electric wire (1), then an AC power supply (between the electrode (5) and the lead cutter (2, 2) While applying 3),
Whether the lead-out cutter (2, 2) contacts the core wire of the electric wire (1) by measuring the voltage value between the AC power source (3) and the electrode (5) by the detection means (4). In a core wire flaw detection method for detecting whether or not the cutting cutter (11, 11) and the lead-out cutter (2, 2), the capacitance between the core wire of the electrode (5) and the electric wire (1) and A core wire flaw detection method, characterized in that insulation is performed via an insulator (14, 14) having an electrostatic capacitance obtained based on the relationship with the detection sensitivity of the detection means (5). 2. A detection head (DH) constituting an electrode (5) used in the core wire flaw detection method according to claim 1, wherein a bell-shaped guide surface is provided on a side into which the electric wire (1) is inserted. A hollow insulating member (21) having (21a) formed therein, and an electrode (23) arranged inside the insulating member (21) so as to face the electric wire (1) and connected to the detecting means (4). ) And a detection head.