JP2023035220A - Sheet-like object defect detection device - Google Patents

Abstract

To provide a sheet-like object defect detection device with which it is possible to detect the presence of holes for even a sheet-like object such as a thin film which is difficult to check for the presence/absence of holes by a camera.SOLUTION: A sheet-like object 86 is located in an inspection region 21 by sheet-like object arrangement mechanisms 21a, 21b. An ultrasonic transmitter 22 is located on one side across the inspection region 21 and an ultrasonic receiver 24 is located on the other side. A determination device 26 compares the sound volume of the ultrasonic wave received by the ultrasonic receiver 24 with a reference value and determines that there exists a defect in a portion of the sheet-like object 86 that is located in the inspection region 21 when the sound value is greater than or equal to the reference value. An attenuator 28 for attenuating the sound volume of an ultrasonic wave is located between the ultrasonic transmitter 22 and the inspection region 21 and/or between the inspection region 21 and the ultrasonic receiver 24. Drive devices 20a, 20b move the sheet-like object 86 and the inspection region 21 relatively to each other.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a sheet defect detection apparatus, and more particularly to a technique for detecting defects in a sheet using ultrasonic waves.

It is known to use ultrasonic waves to detect defects in sheet materials. For example, FIG. 8 is a block diagram of an ultrasonic seam detector. As shown in FIG. 8, an ultrasonic transmitter 3 and an ultrasonic receiver 5 are arranged on both sides of a conveying path of a web (strip-shaped sheet) 4, and the reception signal C output from the ultrasonic receiver 5 is Based on the level, seams of the web 4 that are connected by tape or the like and are thicker than normal portions are detected (see Patent Document 1, for example).

JP-A-2-179472

2. Description of the Related Art It is common practice to photograph a sheet with a camera while conveying a continuous sheet, and detect the presence or absence of holes in the sheet from the image. Here, the sheet-like object is a laminate, and it is difficult for a camera to detect holes in the intermediate layer of the laminate. Moreover, even if the sheet-like object is a transparent film, it is difficult to detect holes.

Therefore, a transmitter that transmits ultrasonic waves and a receiver that receives ultrasonic waves that have passed through the sheet are arranged so as to sandwich the sheet, and the volume of the ultrasonic waves received by the receiver is detected. , to determine the presence or absence of a hole in the layer to be detected.

However, when the layer to be detected is like a thin film, the volume of transmitted ultrasonic waves increases, and it may be difficult to determine the difference in volume due to the presence or absence of holes.

In view of such circumstances, the problem to be solved by the present invention is to provide a sheet-shaped object that is difficult to determine the presence or absence of a hole with a camera and that can detect the presence or absence of a hole even in a sheet-shaped object such as a thin film. An object of the present invention is to provide a defect detection device.

In order to solve the above-mentioned problems, the present invention provides a sheet defect detection apparatus configured as follows.

The sheet defect detection apparatus includes (a) a sheet placement mechanism for placing a sheet in an inspection area, and (b) a sheet placement mechanism arranged on one side of the inspection area in the inspection area. (c) the other side of the sheet placed in the inspection area on the other side across the inspection area; (d) comparing the volume of the ultrasonic waves received by the ultrasonic receiver with a reference value, and when the volume is equal to or greater than the reference value, (e) between the ultrasonic transmitter and the inspection area, and between the inspection area and the ultrasonic wave reception. and (f) an attenuation layer for attenuating the sound volume of the ultrasonic waves disposed at least one of a space between the device and the inspection area, and (f) relative movement between the sheet-like object and the inspection area. and a driving device for moving one or both of the arranged sheet-like object and the ultrasonic transmitter, the ultrasonic receiver, and the attenuation layer.

According to the above configuration, the ultrasonic wave is transmitted from the ultrasonic transmitter so that the output signal output by the ultrasonic receiver after receiving the ultrasonic wave has a discriminable level difference according to the presence or absence of holes in the sheet-like material. Attenuate the ultrasonic waves appropriately by the attenuation layer. This makes it possible to detect the presence or absence of a hole even in a sheet-like material that easily transmits ultrasonic waves. Since defects are detected based on the sound volume of ultrasonic waves that pass through the sheet-like material, it is possible to detect the presence or absence of holes even in a sheet-like material in which it is difficult to determine the presence or absence of holes with a camera.

Preferably, the driving device moves the sheet-like object arranged in the inspection area.

In this case, it is easy to inspect the sheets continuously.

Preferably, the damping layer is a resin film.

In this case, it is easy to appropriately attenuate the volume of the ultrasonic waves.

Preferably, the sheet-like material is formed by sandwiching a layer to be detected between first and second nonwoven fabric layers. The discriminating device discriminates the defect of the layer to be detected.

In this case, it is possible to detect defects in the layer to be detected, which is difficult to detect from an image.

Preferably, a plurality of sets of the ultrasonic receivers and the ultrasonic transmitters are arranged so as to intersect a direction in which the sheet-shaped object and the inspection area move relative to each other and to be aligned in a direction parallel to the inspection area. It is

In this case, the defect detection accuracy can be made substantially uniform in the width direction of the sheet.

According to the present invention, by providing the attenuation layer, it is difficult for a camera to determine the presence or absence of a hole, and even in a sheet-like object such as a thin film, the presence or absence of a hole can be detected.

1 is an overall view of a composite sheet manufacturing apparatus; FIG. (Example 1) 1 is a schematic diagram of a defect detection device for a sheet-like object; (Example 1) FIG. 2 is an explanatory diagram of a main part configuration; (Example 1) It is a flow diagram of detection operation. (Example 1) FIG. 4 is an explanatory diagram of defect detection; (Example 1) It is a graph of a detection signal. (Example 1) FIG. 2 is an explanatory diagram of a main part configuration; (Modification 1, Modification 2) 1 is a block diagram of an ultrasonic seam detector; FIG. (Example 1)

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1> A sheet defect detection apparatus 16 (hereinafter referred to as defect detection apparatus 16) of Embodiment 1 will be described with reference to FIGS. 1 to 7. FIG.

FIG. 1 is a schematic diagram showing the overall configuration of a composite sheet manufacturing apparatus 10 including a defect detection device 16. As shown in FIG.

As shown in FIG. 1, the composite sheet manufacturing apparatus 10 includes a resin sheet manufacturing apparatus 12, a sheet bonding apparatus 14, a defect detection apparatus 16, and a marking apparatus 18. Each sheet 80, 82, 84, 86 is , in the directions indicated by arrows 80x, 82x, 84x and 86x.

The resin sheet manufacturing apparatus 12 discharges a heat-melted resin material in the form of a film from a die 12a, and cools and stretches the discharged intermediate by cooling rolls 12b and 12c to form a resin sheet 80.

The sheet joining device 14 overlaps nonwoven fabric sheets 82 and 84 on both sides of the resin sheet 80 formed by the resin sheet manufacturing device 12, and conveys the laminated sheets 80, 82 and 84 along the outer peripheral surface of the anvil roll 14a. The sheets 80, 82, 84 are then bonded together at appropriate locations using the ultrasonic device 14b to form a composite sheet 86. As shown in FIG.

The defect detection device 16 inspects the intermediate resin sheet 80 of the composite sheet 86 for defects such as holes. Guide rolls 21a and 21b arranged before and after the main part 20 of the defect detection device 16 are a sheet arrangement mechanism for arranging the composite sheet 86 in the inspection area 21, which will be described later.

FIG. 2 is an enlarged view of the essential part 20 of the defect detection device 16. As shown in FIG. As shown in FIGS. 1 and 2, the defect detection device 16 includes an ultrasonic transmitter 22, an ultrasonic receiver 24, a discrimination device 26, and an attenuation layer 28. As shown in FIG.

The ultrasonic wave transmitter 22 and the ultrasonic wave receiver 24 are disposed so as to sandwich the transport path 87 of the composite sheet 86, and the transmission surface 22a of the ultrasonic wave transmitter 22 transmitting the ultrasonic wave and the ultrasonic wave of the ultrasonic wave receiver 24 are arranged. The receiving surfaces 24a for receiving sound waves are arranged so as to face each other. A portion of the area where the ultrasonic transmitter 22 and the ultrasonic receiver 24 face each other and intersects with the transport path 87 is the inspection area 21 . The ultrasonic transmitter 22 is located on one side (downward in the drawing) of the transport path 87, that is, on one side across the inspection area 21. The transmitting surface 22a is one main surface of the composite sheet 86 transported along the transport path 87. are placed facing each other. The ultrasonic receiver 24 is located on the other side (upper side in the drawing) of the transport path 87, that is, on the other side across the inspection area 21. The receiving surface 24a is the other main surface of the composite sheet 86 transported along the transport path 87. are placed facing each other.

The attenuation layer 28 is disposed between the ultrasonic transmitter 22 and the examination region 21 and attenuates the volume of ultrasonic waves emitted from the ultrasonic transmitter 22 and reaching the transport path 87 . For example, the damping layer 28 is adhered to the mounting bracket 27 so as to cover the through hole 27a of the mounting bracket 27 . The mounting bracket 27 is mounted so that the through hole 27a is arranged in a region where the transmitting surface 22a of the ultrasonic transmitter 22 and the receiving surface 24a of the ultrasonic receiver 24 face each other. A transmitting surface 22a of the transmitter 22 and a receiving surface 24a of the ultrasonic receiver 24 are arranged in a region facing each other.

As shown in FIG. 2, the determination device 26 receives an output signal 24s from the ultrasonic receiver 24 . The determination device 26 includes, for example, a PLC (Programmable Logic Controller, sequencer), and based on the output signal 24s from the ultrasonic receiver 24, the volume of the ultrasonic waves received by the ultrasonic receiver 24 is greater than or equal to a reference value. If the value is equal to or greater than the reference value, it is determined that there is a defect, and a defect detection signal 26s is sent to the marking device 18 .

The marking device 18 sticks a defect sticker indicating the position of the defect on the composite sheet 86 based on the defect detection signal 26s. The inspected composite sheet 86 is sandwiched between a pair of transport rolls 20a and 20b, at least one of which is rotationally driven, and transported to a stocker or the like as indicated by an arrow 86z. The transport rolls 20a and 20b are driving devices that move the composite sheet 86 so that the composite sheet 86 and the inspection area 21 move relative to each other.

The composite sheet 86 is a sheet-like object in which a detection target layer made of the resin sheet 80 is sandwiched between first and second nonwoven fabric layers made of the nonwoven fabric sheets 82 and 84 . The discriminating device 26 discriminates defects such as holes in the layer to be detected, that is, the resin sheet 80 .

Further description will be made with reference to the explanatory diagrams of FIGS. 3 and 7. FIG.

As shown in FIG. 3A, in a first state in which only the attenuation layer 28 is arranged between the ultrasonic transmitter 22 and the ultrasonic receiver 24 which are arranged to face each other, ultrasonic waves Ultrasonic waves 23 emitted from the transmitter 22 pass through the attenuation layer 28 . The ultrasonic receiver 24 receives the ultrasonic waves 23 a that have passed through the attenuation layer 28 .

As shown in FIG. 3B, in a second state in which a sheet 81 conveyed in a direction indicated by an arrow 81x is placed between the attenuation layer 28 and the ultrasonic receiver 24, ultrasonic waves are transmitted. Ultrasonic waves 23 emitted from the device 22 pass through the damping layer 28 and the sheet-like material 81 . The ultrasonic receiver 24 receives the ultrasonic waves 23 b that have passed through the attenuation layer 28 and the sheet-like material 81 .

The attenuation layer 28 is configured to produce a distinguishable level difference in the output signal 24s output by the ultrasonic receiver 24 in the first and second states.

With this configuration, as shown in FIG. 3(c), a hole 81x opened in a part of the sheet 81, that is, a hole 81x penetrating between the main surfaces of the sheet 81 serves as an ultrasonic transmitter. 22 and the ultrasonic receiver 24 pass through the area facing each other, the output signal 24s output from the ultrasonic receiver 24 changes temporarily, and the passage of the hole 81x can be detected by this change.

That is, the ultrasonic wave is transmitted from the ultrasonic wave transmitter 22 so that the output signal 24s output by the ultrasonic wave receiver 24 after receiving the ultrasonic wave has a discriminable level difference according to the presence or absence of the hole 81k in the sheet-like object 81. The transmitted ultrasonic waves 23 are appropriately attenuated by the attenuation layer 28 . This makes it possible to detect the presence or absence of the hole 81k even if the sheet-like object 81 is a resin film or the like that easily transmits ultrasonic waves. Since defects are detected based on the volume of ultrasonic waves that pass through the sheet-like object 81, the presence or absence of holes can be detected even in a sheet-like object in which the presence or absence of holes is difficult to determine with a camera.

Instead of placing the attenuation layer 28 between the ultrasonic transmitter 22 and the examination region 21 as shown in FIGS. 3(b) and 3(c), as shown in FIG. An attenuation layer 28a may be arranged between the inspection region 21 and the ultrasonic receiver 24, in which the sheet-like material 81 conveyed in the indicated direction is arranged. Also, as shown in FIG. 7(b), between the ultrasonic wave transmitter 22 and the inspection area 21 in which the sheet-like object 81 conveyed in the direction indicated by the arrow 81x is arranged, and between the inspection area 21 and the ultrasonic wave receiving area. Damping layers 28b, 28c may be placed both between and between the vessel 24. FIG.

The damping layers 28, 28a, 28p, 28q can also be multi-layered.

Next, the operation of the defect detection device 16 will be described with reference to the operation flow diagram of FIG.

As shown in FIG. 4, when the composite sheet manufacturing apparatus 10 starts operating and the composite sheets 86 are continuously formed (S10), based on the output signal 24s from the ultrasonic receiver 24 (S12), The determination device 26 of the defect detection device 16 starts determination of defects such as holes (S14). For example, when the output signal 24s from the ultrasonic receiver 24 exceeds the threshold and the duration of the state of exceeding the threshold is longer than or equal to the first predetermined time, the portion of the composite sheet 86 placed in the inspection area 21 is determined to be defective.

When a defect is detected (NG), the discriminating device 26 sends a defect detection signal 26s to the marking device 18 . The marking device 18 affixes a defect seal to the composite sheet 86 based on the defect detection signal 26s (S18).

The composite sheet manufacturing apparatus 10 continues operation even if no defect is detected (OK) or if a defect is detected (NG) (S16).

Further, the determination device 26 of the defect detection device 16 determines whether to continue the operation of the composite sheet manufacturing device 10 . For example, when the duration of the state in which the output signal 24s from the ultrasonic receiver 24 exceeds the threshold is equal to or longer than a second predetermined time longer than the first predetermined time, or the defect is detected within the third predetermined time. When the number of times of detection exceeds a predetermined number of times, a stop signal is sent to the control device that supervises the overall control of the composite sheet manufacturing apparatus 10 (S20). The operation stop signal causes the composite sheet manufacturing apparatus 10 to stop operation (S22).

As described above, it is easy to continuously inspect the composite sheets 86 by inspecting the continuously formed composite sheets 86 as they pass through the inspection area 21 .

Next, a prototype example of the defect detection device 16 will be described with reference to FIGS. 5 and 6. FIG. FIG. 5 is a plan view seen from the direction indicated by arrow 86y in FIG.

As shown in FIG. 5, in order to inspect a resin sheet 88 having a width 89 of 400 mm, ten sets of ultrasonic receivers 24 and ultrasonic transmitters 22 were arranged at regular intervals so as to line up in the width direction of the conveying path. . That is, the ten pairs of ultrasonic receivers 24 and ultrasonic transmitters 22 intersect the direction in which the resin sheet 88 and the inspection area 21 move relative to each other (the conveying direction of the resin sheet 88 indicated by an arrow 88x), They were arranged at regular intervals so as to line up in a direction parallel to the region 21 . A distance 25 between the ultrasonic receiver 24 and the ultrasonic transmitter 22 was set to 40 mm.

A common damping layer 28 was arranged between the ultrasound transmitter 22 and the examination region 21 . The thickness of the resin sheet 88 is 25-100 μm. A resin sheet made of the same material as the resin sheet 88 and having a thickness of 18 to 85 μm was used for the damping layer 28 . Of the ten sets of ultrasonic receivers 24 and ultrasonic transmitters 22, only some of the sets may have a common attenuation layer, or each set may have a separate attenuation layer.

For the ultrasonic receiver 24 and the ultrasonic transmitter 22, an ultrasonic sensor for seam detection (model: US-T04AN) provided by Takenaka Electronics Co., Ltd. was used.

The defect detection device 16 of the prototype example was able to detect a hole 88k formed in the resin sheet 88 and having a transport direction dimension 88a of 10 mm and a width direction dimension 88b of 30 mm.

FIG. 6 is a signal waveform diagram of the output signal 24s output from the ultrasonic receiver 24, where the horizontal axis represents time and the vertical axis represents the output level. As shown in FIG. 6, when the hole 88k of the resin sheet 88 passes through the area where the ultrasonic receiver 24 and the ultrasonic transmitter 22 face each other, the output level temporarily becomes sufficient compared to the normal area. , the hole 88k could be detected.

<Modification 1> Instead of moving the sheet-like object, the ultrasonic transmitter, the ultrasonic receiver, and the attenuation layer may be moved integrally, that is, while maintaining their mutual positional relationship. In this case, a driving device is provided for moving the ultrasonic transmitter, the ultrasonic receiver, and the attenuation layer so that the sheet-like object and the inspection area are moved relative to each other. For example, in the configuration shown in FIG. 5, while the resin sheet 88 is stationary, the ultrasonic wave transmitter 22, the ultrasonic wave receiver 24, and the attenuator 22 are arranged in the longitudinal direction of the resin sheet 88 (the direction indicated by the arrow 88x). The layers 28 are inspected while moving together. In this case, detailed inspection can be performed by repeatedly moving the ultrasonic transmitter 22 and the like.

<Modification 2> Both the sheet material, the ultrasonic transmitter, the ultrasonic receiver, and the attenuation layer may be moved. In this case, a first driving device for moving the sheet so that the sheet and the inspection area move relative to each other; A receiver and a second drive for moving the damping layer.

<Summary> As described above, the defect detection device 16 is provided with the attenuation layer 28, so that it is difficult for the camera to determine whether there is a hole or not, and even if the sheet-shaped object such as a thin film is used, the hole is detected. can detect the presence or absence of

It should be noted that the present invention is not limited to the above embodiments, and can be implemented with various modifications.

For example, the sheet defect detection apparatus of the present invention can detect defects not only in composite sheets but also in transparent, translucent, or opaque single-layer or multiple-layer sheet materials.

16 defect detection device 20a, 20b transport roll (driving device)
21 inspection area 21a, 21b guide roll (sheet arrangement mechanism)
22 Ultrasonic transmitter 24 Ultrasonic receiver 26 Discriminator 28, 28a, 28p, 28q Attenuation layer 80 Resin sheet (layer to be detected)
81 sheet material 82 nonwoven fabric sheet (nonwoven fabric)
84 non-woven sheet (non-woven fabric)
86 Composite sheet (sheet-like material)
87 Conveyance path 88 Resin sheet (sheet-like object)

Claims (5)

a sheet placement mechanism for placing the sheet in the inspection area;
an ultrasonic transmitter arranged on one side of the inspection area so as to face one main surface of the sheet-shaped article placed in the inspection area;
an ultrasonic receiver disposed on the other side of the inspection area so as to face the other main surface of the sheet-shaped article placed in the inspection area;
The sound volume of the ultrasonic waves received by the ultrasonic receiver is compared with a reference value, and when the sound volume is equal to or higher than the reference value, it is determined that there is a defect in the portion of the sheet-like object arranged in the inspection area. a discrimination device for judging,
an attenuation layer that attenuates the sound volume of the ultrasonic waves, disposed between the ultrasonic transmitter and the examination region and between the examination region and the ultrasonic receiver, at least one of the layers;
Among the sheet-shaped article arranged in the inspection area, the ultrasonic transmitter, the ultrasonic receiver, and the attenuation layer, such that the sheet-shaped article and the inspection area move relative to each other, a driving device for moving either one or both;
A defect detection device for a sheet-like object. 2. The sheet defect detection apparatus according to claim 1, wherein said driving device moves said sheet placed in said inspection area. 3. The sheet defect detection apparatus according to claim 1, wherein said damping layer is a resin film. The sheet-shaped object is formed by sandwiching a layer to be detected between first and second nonwoven fabric layers,
4. The sheet defect detection apparatus according to claim 1, wherein said discriminating device discriminates said defect of said layer to be detected. A plurality of sets of the ultrasonic receivers and the ultrasonic transmitters are arranged so as to intersect a direction in which the sheet-like object and the inspection area move relative to each other and to be aligned in a direction parallel to the inspection area. 5. The sheet defect detection apparatus according to claim 1.

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