JPH08159711A - Method and apparatus for detecting winding start position of steel plate coil - Google Patents

Abstract

PURPOSE: To detect a winding start position of a steel place coil automatically. CONSTITUTION: A laser type distance measuring sensor 20 is inserted into the center of an inner diameter hole 2a of a steel plate coil and the sensor 20 is turned once to measure the shape of an inner circumferential surface of the inner diameter hole 2a. As a step equal to at least the thickness of a steel plate exists at a winding start position thereof, it is detected distinguishing from other irregularities on the inner circumferential surface. Information on a winding start position is used in combination with an automatic device where a label is applied closer to the winding start position or a notch of an inner diameter ring is mounted avoiding the winding start position or in other cases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a winding start end position of a steel sheet coil.

[0002]

2. Description of the Related Art There are roughly two types of winding methods for steel sheet coils. One is to grip the end of the steel plate with a grip attached to the winding shaft and wind it onto the winding shaft, and the other is to use the felt to hold the steel plate and wind it onto the winding shaft without using the grip. Is the way. In general, thick steel plates such as hot rolled coils are wound in the former, and thin steel plates such as lomo are wound in the latter. When the winding start end is gripped by the grip, the start end tends to bend and protrude inward in the inner diameter hole of the steel plate coil in a curl shape.

In a thick steel plate coil which is only wrapped with a hoop band and not wrapped with paper, a label is attached near the winding start end, which describes the material and dimensions of the steel plate. Since the glue remains even if the label is peeled off, cut off the glued part together with the curl. In order to minimize the cut-off portion, the label is manually attached at a predetermined position near the curl portion or the winding start end.

In a thin steel plate coil in which an iron plate is further wrapped on a paper package, inner diameter rings may be fitted to both ends of the inner diameter hole. When the inner diameter ring hits the curl portion, a gap is created between the inner diameter portion and the inner diameter ring. This is disadvantageous in terms of moisture resistance. In addition, the inner peripheral paper that wraps the inner diameter portion may be broken. Therefore, when mounting the inner diameter ring, it is necessary to manually align the notch provided in the inner diameter ring with the curl portion.

When mounting the inner peripheral paper in the inner diameter hole, a rotatable mandrel having a plurality of segments which can be expanded and contracted in the radial direction is used. The inner peripheral paper is wound around the mandrel, the mandrel is inserted into the inner diameter hole, the segment is enlarged, and the inner peripheral paper is attached to the inner diameter hole. At this time, when one of the segments hits the curl portion, a gap is formed between the inner peripheral paper pressed by the segment and the inner peripheral surface of the inner diameter hole. This gap remains even after removing the mandrel from the inner diameter. This is also inconvenient in terms of moisture resistance. In the past, an operator checked each eye and positioned the curl portion in the division gap between the segments to enlarge the segment.

[0006]

It is inconvenient in terms of efficiency and cost that an operator checks the curl portion one by one.

An object of the present invention is to embody a method and apparatus for automatically detecting the winding start end position of a steel plate coil.

[0008]

The present invention uses a laser distance measuring sensor to detect the winding start position of a steel plate coil. By inserting this sensor into the center of the inlet of the inner diameter hole of the steel plate coil and making about one rotation, the distance from the center of the inner diameter hole to the inner peripheral surface of the inner diameter hole is sampled at multiple points at equal intervals in the circumferential direction. Since there is a step at least equal to the plate thickness of the steel sheet coil at the winding start end, this step is detected by the sensor. That is, as described in the claims,

A laser distance measuring sensor disposed at the center of the inner diameter hole of the steel plate coil is continuously rotated at an angle of at least 360 ° around the axis of the steel plate coil, and the inner circumference of the inner diameter hole is extended from the sensor. A step of sampling the distance R to the surface at a plurality of points at equal intervals in the circumferential direction,

A step of comparing and calculating the measured value measured by the sensor with the immediately preceding measured value to calculate the variation ΔR;

A method for detecting a winding start position of a steel sheet coil, which comprises a step of storing a rotation angle of the distance measuring sensor when the change amount ΔR reaches a maximum value exceeding a predetermined value as a winding start end position.

The measured value measured by the sensor is Dn (n
= 1 ... n), the arithmetic mean value of the first measurement value and the second measurement value is N2, the arithmetic mean value of the arithmetic mean value N2 and the third measurement value is N3, and the arithmetic mean value Nn-1. When the arithmetic mean value with the n-th measured value is Nn, the rotation angle of the distance measuring sensor when the measured value Dn-the arithmetic average value Nn-1 becomes the maximum value exceeding a predetermined value, the steel plate is the rotation angle. A method for detecting the winding start position of a steel plate coil, which comprises a step of storing the winding start position of the coil.

The laser-type measuring device is provided at the tip of the core shaft of a rotatable mandrel having a plurality of radially expandable / retractable divided segments for inserting and pasting a cylindrically wound inner peripheral paper into an inner diameter hole of a steel plate coil. Before mounting the distance sensor and inserting and pasting the inner peripheral paper, the tip of the mandrel is inserted into the end of the inner diameter hole of the steel plate coil, and the mandrel is rotated by at least 360 °. Starting position detection method.

A laser distance measuring sensor which can be inserted into the center of the inner diameter hole of the steel plate coil and can measure the distance to the inner peripheral surface of the inner diameter hole,

Rotating means for continuously rotating the distance measuring sensor at an angle of at least 360 ° around the axis of the inner diameter hole of the steel plate coil;

The measured values of the distance measuring sensor at a plurality of positions at equal intervals in the circumferential direction on the inner peripheral surface of the inner diameter hole are stored in association with the rotation angle of the rotating means, and the previous measured value of the distance measuring sensor is stored. And a calculation means for comparing and calculating a change amount ΔR between the present measurement value and the present measurement value, and calculating whether or not the change amount R has reached a maximum value exceeding a predetermined value.

Output means for outputting the rotation angle of the rotating means at the determined measurement point as the winding start end position of the steel plate coil based on the maximum determination result of the change amount R by the calculating means. Winding start position detection device for steel sheet coil.

The rotating means is a rotatable mandrel having a plurality of radially expandable / retractable divided segments for inserting and pasting a cylindrically wound inner peripheral paper in an inner diameter hole of a steel plate coil, A winding start end position detecting device for a steel plate coil, wherein the distance measuring sensor is attached to a tip of a core shaft of the mandrel.

The winding start position of the steel sheet coil is automatically detected by the above means.

[0020]

[Function] Depending on the time until the laser light emitted from the laser distance measuring sensor is reflected by the inner peripheral surface of the steel plate coil inner diameter hole and returns to the sensor again, from the center of the sensor, that is, the inner diameter hole to the inner peripheral surface. Is calculated. Therefore, the shape of the inner peripheral surface can be known by rotating the sensor once.
Since there is a step at least equal to the plate thickness of the steel plate at the winding start position, the rotation start position is calculated from the rotation angle of the sensor when this step is detected.

Irregularities due to burrs and grease are also present on the inner peripheral surface. In order to distinguish the step difference at the winding start end from these irregularities, the minimum change amount ΔR or the tolerance that can be recognized as the step difference at the start end is optimally selected and set according to the plate thickness of the steel sheet. It is not judged as a step at the start. At the start of winding, a step at least equal to the plate thickness suddenly appears. That is, the value of the distance measurement data changes suddenly. Then, when the change in the distance measurement data is larger than a predetermined tolerance corresponding to the plate thickness and is maximum, the winding start end is determined. By this method, it is possible to distinguish between unevenness on a relatively smoothly continuous surface and a step at the winding start end.

The shape of the winding start end varies depending on the type of the steel plate coil and the situation at the time of winding, but is not constant, but when a gripped portion such as a hot rolled coil is provided, it is generally located inside the inner diameter hole. It often curls smoothly.
There are ultrasonic sensors and magnetic sensors as well as laser sensors as distance measuring sensors or shape sensors,
It is difficult for these to reliably detect subtle shape changes that continue smoothly.

If the laser distance measuring sensor is rotated at the exact center position of the inner diameter hole of the steel plate coil and the inner diameter hole is a substantially perfect circle other than the winding start end, the sensor detects the step as the winding start end. There is no problem because there is only one step. However, it is difficult to position the sensor in the exact center of the bore. Further, the inner diameter hole of the steel plate coil is generally deformed into an elliptical shape with the short axis being the vertical direction due to the influence of the weight of the steel plate coil.
In addition, in the vicinity of the winding start end, the shape near the winding start end may be disturbed depending on the state of gripping of the winding shaft by the gripping device or the start of winding. Therefore, when viewed from the distance measurement data of the sensor, a so-called "step" may be detected more than once. Even in such a case, in order to reliably detect the winding start end, instead of simply comparing the distance measurement data of the adjacent measurement points, the arithmetic mean value of the distance measurement data of the preceding measurement points is used. Method, and this value is compared with the distance measurement data measured this time. Then, the unevenness or the step on the inner peripheral surface is regarded as a value smaller than the actual step value, and when the value is smaller than a predetermined value, it is excluded from the winding start end determination target.

As a means for rotating the distance measuring sensor, it is very convenient to use a mandrel in which the inner peripheral paper is inserted and mounted in the inner diameter hole of the steel plate coil because it is well matched with the flow of the packing process of the steel plate coil. In other words, thin steel plate coils such as lomo are double-wrapped with a paper wrapping and an iron plate wrapping as a measure against moisture and deformation, but when mounting the inner peripheral paper in the inner diameter hole, the mandrel segment and the winding start end of the steel plate coil abut. The winding start must be known, at least when enlarging the segment, since it is necessary to avoid The present invention attaches a distance measuring sensor to the tip of the mandrel core shaft,
Immediately before inserting the inner peripheral paper, the tip of the mandrel is inserted into the end of the inner diameter hole, and the mandrel is rotated once in this state to detect the step difference at the winding start end. The detected start-end position information is supplied to a packaging device or the like that requires the information along with the process movement of the steel plate coil. For example, in the step of wrapping a steel plate coil with an iron plate, there is a step of fitting the inner diameter ring to both ends of the inner diameter hole, and the starting end position data is provided to a device for mounting the inner diameter ring. The inner diameter ring is formed with a notch for avoiding the winding start end of the steel plate coil, and the inner diameter ring mounting device mounts the notch of the inner diameter ring on the inner diameter portion in accordance with the supplied start end position data. Also, in the case of a hot rolling roll that only hangs the hoop band, the starting position information is supplied to the device that automatically attaches the label that describes the type of coil, etc., and the labeling device automatically attaches the label to a predetermined position near the starting position. Affix to

[0025]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an outline of a steel plate coil 2 and a mandrel 4 in an inner peripheral paper insertion mounting process for the inner diameter hole of the steel plate coil. At the winding start end of the steel plate coil 2, there is left the gripped portion 1 which is slightly curled and deformed inward of the inner diameter hole due to the grip force when the steel plate coil 2 is wound. The present invention can of course detect the winding start end of a relatively thin steel plate coil in which the gripped portion 1 does not remain.

The mandrel 4 is an inner diameter hole 2a of the steel plate coil 2.
The inner peripheral paper 3 is inserted into and mounted on the mandrel 4, and the segment 4a is divided into a plurality of segments which can be inserted into the inner diameter hole 2a as shown in FIG.
It has a core shaft 4b that supports a. A link mechanism 6 for expanding and contracting the segment 4a in the radial direction is arranged between the core shaft 4b and the segment 4a. Core axis 4b
Is connected to driving means in the rotational direction and the front-back direction (not shown), and rotates and moves the mandrel 4 back and forth in the step of detecting the winding start end of the steel plate coil 2 and the step of inserting and mounting the inner peripheral sheet 3 by the mandrel 4. The segment 4a is a long and thin plate having an arcuate cross section as shown in FIGS. Two segments 4
As shown in FIGS. 2 and 3, a paper grip 8 for partially crimping both ends of the inner peripheral paper 3 to the surface of the segment 4a is openably and closably provided by a cylinder 10 at the tip of a. Reference numeral 12 is a support shaft around which the paper grip 8 rotates. At the tip of the two segments 4a, the inner paper 3
Vacuum suction devices 14 and 16 for sucking and holding the front end and the rear end of each of them on the segment 4a are attached.

A touch sensor 18 is attached to the tip of each segment 4a. When the touch sensor 18 comes into contact with the edge of the inner diameter hole 2a due to an error such as misalignment when inserting the mandrel 4 into the inner diameter hole 2a,
This is to prevent the mandrel 4 from being damaged by stopping the inserting operation of the mandrel 4 in an emergency.

A laser distance measuring sensor 20 is attached to the tip of the core shaft 4b of the mandrel 4 in a state of protruding from the tip of the mandrel 4. The emission direction of the laser beam is aligned with the radial direction of the inner diameter hole 2a as shown in FIG. 4 (A), and the laser reflected light reflected by hitting the inner peripheral surface of the inner diameter hole 2a returns to the sensor 20 along the same path as the incident path to emit the laser beam. The distance R from the sensor 20 to the inner peripheral surface of the inner diameter hole 2a is measured by the time difference between the firing and the return.

All the data obtained by the sensor 20 is shown in FIG.
Is processed by the device. That is, the distance measurement data is the amplifier 2
The data is continuously recorded in the recorder 23 via 2. Further, the distance measurement data is sent to the arithmetic unit 24 via the amplifier 22, where the calculation shown in FIGS. 6 and 7 is performed to calculate the starting end position of the steel plate coil 2, and the calculation result is the gripped position display unit. In addition to being displayed on 26, the steel sheet coil 2 is sent to the related apparatus along with the process movement.

FIG. 6 is a flow chart showing the contents of calculation in the calculation device. First, when it is confirmed that the laser distance measuring sensor 20 at the tip of the mandrel 4 is inserted into the end of the inner diameter hole 2a of the steel plate coil 2 (S
1), the laser of the sensor 20 is emitted (S
2). At this time, the mandrel 4 is in a rotation stopped state, and the sensor 20 has not started measurement yet. This standby state continues until the timer device starts counting and counts 2.5 seconds (S3). The reason is that immediately after the mandrel 4 has advanced and stopped, the sensor 20 often shakes due to the impact of the advance or stop of the mandrel 4, and it is necessary to wait until the shake naturally disappears.
The reason for setting the time to 2.5 seconds is that it was confirmed as the result of the experiment that the waiting time was the minimum necessary. After 2.5 seconds have elapsed, the mandrel 4 starts to rotate, and the sensor 20 outputs a measurement pulse as distance measurement data (S4). The rotation direction of the mandrel 4 is the same as the rotation direction in the inserting and mounting process of the inner peripheral paper 3 (the same direction as the rotation direction when winding the steel plate coil 2). This is to detect the winding start end of the steel plate coil 2 in a state where the inner peripheral paper 3 is usually wound around the mandrel 4. The inner peripheral paper 3 is inserted while rotating the mandrel 4 in the same direction as the winding direction of the steel sheet coil 2 in order to prevent the winding end end of the inner peripheral paper 3 from being caught in the winding start end. is there.

The measurement pulse is a difference (change amount ΔR) between the maximum value and the minimum value of the input value (distance R detected by the distance measuring sensor 20) between the measurement timing pulses. Measurement is performed by the sensor 20 at multiple measurement points at equal intervals in the circumferential direction on the inner peripheral surface of the inner diameter hole 2a, and each distance measurement data is a signal of a tolerance or more (S5). It is determined whether or not it is a signal (S6) and whether it is larger than the previous detection signal (S7). The determination as to whether or not it is the first signal is for the comparison determination in step S7. The above method is the method according to claim 1 of the claims.

On the other hand, the previous average value comparison mode described in claim 2 can also be used. In this previous average value comparison mode, the comparison value of FIG. 7 is used instead of the comparison with the previous detection signal in step S7. As for this comparison value, the measured value measured by the sensor 20 is Dn (n = 1 ... n), the arithmetic mean value of the first measurement value and the second measurement value is N2, and the arithmetic mean value N2 and the third measurement value are When the arithmetic mean value of is N3,
It is a value represented by the general formula Nn = (Nn-1 + Dn) / 2. In this previous average value comparison mode, the difference between the current input value of the sensor 20 and the previous average value is output. Therefore, the measured pulse output value is small in a gentle change of the distance measurement output data based on the elliptic deformation of the inner diameter hole 2a due to the deflection error of the core shaft 4b of the mandrel 4, that is, the sensor 20, and the self weight of the steel plate coil 2, and the measured pulse output value is small. A large measured pulse output value appears only where there is a sudden change such as 1. As described above, when the previous average value comparison mode is used, the influence of the deflection error of the sensor 20 and the deformation of the steel plate coil 2 inner diameter hole 2a can be suppressed to a small level, so that the false detection of the winding start end position based on these errors can be prevented. .

When the mandrel 4 is rotated by a predetermined rotation angle (at least one rotation, usually, it is further overlapped and rotated to some extent), the measurement is finished (S9).
It is determined whether or not at least one pulse signal with a tolerance or more can be detected in all the measurement points (S10), and if none is detected, the operator temporarily checks the start end and manually operates the start end angle. Input with (S11). When a signal having a predetermined tolerance or more can be detected, the start angle has already been calculated (S8), and the detection is completed (S12).

The tolerance is the first condition that the burrs and grease present on the inner peripheral surface of the inner diameter hole 2a of the steel plate coil 2 are not less than a predetermined value so as not to be erroneously detected as a step at the starting end of the steel plate coil 2, and as shown in FIG. As in B), when the starting end of the steel plate coil 2 does not float and is in close contact with the inner diameter hole 2a, the second condition that the plate thickness at the starting end of the steel plate coil 2 is less than or equal to a predetermined value so as to be reliably detected as a step at the starting end. Is determined as a value that satisfies both. The tolerances are determined by the plate thickness of the steel plate coil 2 in the following four ways, for example, and instruct the arithmetic unit which tolerance is to be selected from a sequencer (not shown) according to the plate thickness of the steel plate coil 2 to be measured.

Plate Thickness of Steel Plate Coil Tolerance Without Grip Part 1 1-2 mm 0.9 mm 〃 2-3 mm 1.4 mm 〃 3 mm or more 2.0 mm Grip Part 1 Included 2.4 mm

Next, the experimental results will be described.

(Type of Sensor 20) Laser Distance Measuring Sensor 20 “LB-300” (Manufacturer: Keyence) Ultrasonic Displacement Sensor 20 “UD-310” (Manufacturer: Keyence) (Steel Plate Coil 2) Starting End Step 0. 6-3.8mm Steel plate used Cold-rolled steel plate Surface condition Rust occurrence part Black part creation (matte spray application) Oil coating part creation (grease hand-painting) (Grip position detection results (see Figures 8-10))

(1) Laser distance measuring sensor 20 Number of tests 60 times Total number of undetectable times 0 Number of test conditions Number of plate thickness 0.6 mm 32 times (Refer to FIG. 8 (1)) Plate thickness 0.6 mm + matte Spray application 10 times (see FIG. 8 (2)) Plate thickness 0.6 mm + grease application 10 times (see FIG. 9 (3)) Plate thickness 3.8 mm 8 times (see FIG. 9 (4))

(2) Ultrasonic distance measuring sensor 20 Number of tests 3 times Number of undetectable times 3

FIG. 8 (1) showing the measurement result of the laser distance measuring sensor is the measurement result of the steel plate coil having the plate thickness t = 0.6 mm. Since the pulse output is generated only once in the figure, the calculation of the start angle in S8 of the flowchart of FIG. 6 is performed only once. In (2) of FIG. 8, the plate thickness t = 0.6.
A black matte spray is applied in a certain length range from the winding start end in mm, and the first measurement pulse is output due to the step created at the boundary of the spray application surface, and then the second measurement pulse at the winding start end. Is being output. The start angle is calculated once with the first pulse output (S
8) Since the second pulse output is larger, the calculated angle is updated in S8.

FIG. 9 (3) shows a case where the plate thickness t = 0.6 mm and grease is applied in a certain length range from the winding start end.
The first measurement pulse is output due to the step formed at the boundary of the grease application surface, and the second measurement pulse is output at the subsequent winding start end. The start angle is calculated once with the first pulse output (S8), but the calculated angle is updated in S8 because the second pulse output is larger.

In FIG. 9 (4), the plate thickness t = 3.8 mm and the gripped portion 1 is present.
The second measurement pulse is output, and the gripped portion 1 outputs the second measurement pulse. The start angle is calculated once with the first pulse output (S8), but the calculated angle is updated in S8 because the second pulse output is larger.

FIG. 10 shows the measurement results using the ultrasonic distance measuring sensor, and no measurement pulse was output including the winding start position.

It should be noted that the sensor 2 is shown in the vertical direction in FIGS.
It represents the distance from 0 to the inner peripheral surface of the inner diameter hole, and the unit of the scale is 10 mm. The horizontal direction represents the time to move to the right, and the unit of the scale is 1 second.

[0045]

As described above, according to the present invention, the position is automatically detected from the step difference at the winding start end of the steel sheet coil by using the laser distance measuring sensor, so that the present invention has been performed manually. It is possible to provide the most important winding start position information when automating labeling and mounting of inner diameter ring.

Further, by mounting the sensor on the tip of the core shaft of the conventional mandrel in which the inner peripheral paper is mounted in the inner diameter hole of the steel plate coil, the winding start end can be detected without newly installing a rotating means of the sensor. In this case, in particular, since the winding start end position can be known before mounting the inner peripheral paper, when the inner peripheral paper is mounted by mandrel expansion, the segment is expanded by matching the segment division gap of the mandrel to the winding start end, The inner peripheral paper can be prevented from being lifted up, because the inner peripheral paper can be pressure-bonded without any gap.

Further, by adopting the previous average value comparison mode, it is possible to prevent erroneous detection of the winding start end position due to a deflection error of the sensor from the center of the inner diameter hole of the steel plate coil or deformation of the inner diameter hole.

[Brief description of drawings]

FIG. 1 is a perspective view of a mandrel 4 of a steel plate coil 2.

FIG. 2 is a sectional view of a mandrel 4.

FIG. 3 is an end view of the mandrel 4.

4A and 4B are front views of a laser distance measuring sensor 20 in a measuring state.

5 is a block configuration diagram of a winding start end position detection device for the steel plate coil 2. FIG.

FIG. 6 is a flowchart of a winding start end position detection method for the steel plate coil 2.

FIG. 7 is a diagram of a concept of a previous average value comparison mode.

8A and 8B are diagrams showing detection results of the laser distance measuring sensor 20.

9 (3) and (4) are diagrams showing detection results of the laser distance measuring sensor 20. FIG.

FIG. 10 is a view showing a detection result of the ultrasonic distance measuring sensor 20.

[Explanation of symbols]

 1 gripped part 2 steel plate coil 2a inner diameter hole 3 inner peripheral paper 4 mandrel 4a segment 4b core axis 20 laser distance measuring sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Iwano 2-18-6 Imai Chuo-ku, Chiba City, Chiba Prefecture Affinity Package Co., Ltd. Chiba Works (72) Inventor Masao Iwata 2-chome, Imai Chuo-ku, Chiba City, Chiba Prefecture 18-6 No. 6 Affinity Package Co., Ltd. in Chiba Works (72) Inventor Mitsuyoshi Sonoyama 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Kawasaki Steel Co., Ltd. in Chiba Works (72) Masaki Aihara Kawasaki, Chuo-ku, Chiba-shi, Chiba Prefecture No. 1 town Kawasaki Steel Co., Ltd. Chiba Works

Claims (5)

[Claims] 1. A laser distance measuring sensor disposed at the center of an inner diameter hole of a steel plate coil is continuously rotated about the axis of the steel plate coil at an angle of at least 360 ° while the sensor detects A step of sampling the distance R to the inner circumferential surface at a plurality of points at equal intervals in the circumferential direction; a step of comparing and calculating the measured value measured by the sensor with the immediately preceding measured value to calculate a change amount ΔR; A method for detecting a winding start position of a steel sheet coil, comprising a step of storing a rotation angle of the distance measuring sensor when ΔR reaches a maximum value exceeding a predetermined value as a winding start position. 2. The measured value measured by the sensor is Dn
(N = 1 ... n), the arithmetic mean value of the first measurement value and the second measurement value is N2, the arithmetic mean value of the arithmetic mean value N2 and the third measurement value is N3, and the arithmetic mean value Nn- When the arithmetic mean value of the 1st and n-th measurement values is Nn, the rotation angle of the distance measuring sensor when the measured value Dn-the arithmetic mean value Nn-1 becomes the maximum value exceeding a predetermined value, 3. The winding start end position detecting method for a steel plate coil according to claim 2, comprising a step of storing the winding start end position of the steel plate coil. 3. The laser at the tip of the core shaft of a rotatable mandrel having a plurality of radially expandable / retractable divided segments for inserting and adhering a cylindrically wound inner peripheral paper in an inner diameter hole of a steel plate coil. A distance measuring sensor is attached, and the tip of the mandrel is inserted into the end of the inner diameter hole of the steel plate coil and the mandrel is rotated at least 360 ° before inserting and pasting the inner peripheral paper. Alternatively, the winding start end position detection method of the steel plate coil according to the item 2. 4. A laser distance measuring sensor that can be inserted into the center of an inner diameter hole of a steel plate coil and can measure the distance to the inner peripheral surface of the inner diameter hole; Rotating means for continuously rotating at least an angle of 360 ° around the axis of the hole, and rotation of the rotating means for measuring values of the distance measuring sensor at a plurality of locations on the inner peripheral surface of the inner diameter hole at equal intervals in the circumferential direction. The change amount ΔR between the previous measured value and the present measured value of the distance measuring sensor is compared and stored while being stored in association with the angle, and it is calculated whether or not the changed amount R becomes a maximum value exceeding a predetermined value. And an output means for outputting the rotation angle of the rotating means at the measurement point where the determination is made as the winding start end position of the steel plate coil, based on the maximum determination result of the change amount R by the calculating means. Of steel coil with Times starting end position detecting device. 5. The rotatable mandrel having a plurality of radially expandable / retractable divided segments for inserting and pasting a cylindrically wound inner peripheral paper in an inner diameter hole of a steel plate coil. 5. The winding start end position detecting device for a steel plate coil according to claim 4, wherein the distance measuring sensor is attached to the tip of the core shaft of the mandrel.