JP2014059256A - Foreign matter inspection method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device capable of detecting a foreign matter with high sensitivity.SOLUTION: A long belt-like sheet 1 is wound on a roll 7 installed in the midway of a conveyance path of the sheet 1. Incident light having a laser beam as a light source is projected parallel to an axial direction of the roll 7 and from one side edge 11 of the sheet 1 toward another side edge 12 onto an inspected portion 20 constituted of a portion wound on the roll 7 or a peripheral portion thereof in the sheet 1. The incident light is reflected by a reflection mirror 26 installed on the other side edge 12 side so that reflection light passes along an optical path the same as an optical path of the incident light. The returned reflection light is received by a light receiver installed on the one side edge 11 side, and a light receiving amount of the reflection light is measured. On the basis of the degree of the light receiving amount, whether or not a foreign matter is present on a surface of the sheet 1 is inspected.

Description

  The present invention relates to a foreign matter inspection method for detecting whether foreign matter is present on the surface of a long belt-like sheet to be conveyed and an apparatus used therefor.

  When manufacturing absorbent articles such as disposable diapers and sanitary napkins, a long strip-shaped raw fabric sheet is unwound from a roll and transported, and various processing is performed during transport to manufacture the desired article. Is common. For example, in order to join an original sheet and another member, operations such as thermocompression bonding using a hot roll or application of an adhesive such as a hot melt adhesive to the original sheet are often performed. . These articles include dust accumulated during the manufacturing process, resin debris adhering to the heat roll, lump that the adhesive has solidified, and foreign matter that originally adheres to the original sheet or is part of the original sheet. May be mixed. Articles containing such foreign substances are excluded as defective products in the manufacturing process. The removal of defective products is generally performed based on the detection of foreign matter using various optical sensors.

  As said optical sensor, what employ | adopted the combination of the light projector arrange | positioned at the side edge side of a sheet | seat and the light receiver arrange | positioned at the other side edge side is known (patent document 1). And 2). When there is a foreign object on the sheet, the amount of light received by the light receiver changes because the light emitted from the projector is blocked by the foreign object. A foreign object is detected by detecting the change.

  In addition, a first projector is disposed on one side edge of the sheet, a first light receiver is disposed on the other side edge, and a second projector is disposed on the other side edge. In addition, it has also been proposed to arrange a second light receiver on one side edge (see Patent Document 3). By adopting such an arrangement and measuring the average value of the amount of light received by each of the two light receivers to detect foreign matter, the detection sensitivity does not change regardless of the position of the foreign matter in the width direction of the sheet. It is described in the same literature that a foreign object can be detected.

Japanese Utility Model Publication No. 64-15953 JP-A-6-180295 Japanese Patent Laid-Open No. 7-190953

  By the way, the solidified product of the above-mentioned adhesive is often transparent or translucent, and such a transparent or translucent solidified product is difficult to block light, so when the methods described in Patent Documents 1 and 2 are used. It is not easy to detect such foreign matter with high sensitivity. When the method described in Patent Document 3 is used, two pairs of a combination of a projector and a light receiver are used, so that the detection sensitivity does not change at any position in the width direction on the sheet. Although the sensitivity is improved as compared with the case where the methods described in Patent Documents 1 and 2 are used, it is necessary to adjust the optical axes of each pair, and adjustment is troublesome. In addition, the installation space is increased by using two pairs of combinations.

  Accordingly, an object of the present invention is to provide a foreign matter inspection method and an apparatus used therefor that can eliminate the above-mentioned drawbacks of the prior art.

The present invention is a foreign matter inspection method for detecting whether or not foreign matter is present in a long belt-like sheet to be conveyed,
Wrap the sheet on a roll installed in the middle of its transport path,
Of the sheet, a laser beam is directed to the inspected portion formed of a portion wound around the roll or in the vicinity thereof, parallel to the axial direction of the roll and from one side edge to the other side edge of the sheet. Irradiate incident light as a light source,
Reflecting the incident light by a reflector installed on the other side edge so that the reflected light passes through the same optical path as the incident light,
The returned reflected light is received by a light receiver installed on the side edge, and the amount of the reflected light received is measured.
The present invention provides a foreign matter inspection method for inspecting whether or not foreign matter is present on the sheet based on the amount of received light.

Further, the present invention is an apparatus suitably used for the detection method.
A foreign matter inspection apparatus for detecting whether foreign matter is present in a long belt-like sheet to be conveyed,
A roll installed in the middle of the sheet conveyance path so that the axial direction is orthogonal to the sheet conveyance direction;
Of the sheet, a laser beam is directed to the inspected portion formed of a portion wound around the roll or in the vicinity thereof, parallel to the axial direction of the roll and from one side edge to the other side edge of the sheet. A projector capable of irradiating incident light as a light source and installed on the side edge;
A reflecting mirror installed on the side of the other side edge so that the reflected light passes through the same optical path as the optical path of the incident light;
It is possible to receive the reflected light that has returned and measure the amount of the reflected light received, and a light receiver installed on the one side edge;
The present invention provides a foreign substance inspection apparatus having a determination unit that determines whether or not a foreign substance exists on the sheet based on received light amount data transmitted from the light receiver.

  According to the present invention, a foreign object can be detected with high sensitivity even if the foreign object to be detected is transparent or translucent. Moreover, according to this invention, the installation space of an apparatus can be made compact.

FIG. 1 is a schematic diagram showing an example in which the detection method and the detection device of the present invention are applied to the manufacture of absorbent articles such as disposable diapers and sanitary napkins. FIG. 2 is a perspective view showing a main part in the vicinity of the roll in FIG. FIG. 3 is a schematic view of the perspective view shown in FIG. FIGS. 4A to 4C are schematic diagrams illustrating the irradiation state of incident light irradiated to the detected part.

  The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 is a schematic diagram showing an example in which the detection method and the detection device of the present invention are applied to the manufacture of absorbent articles such as disposable diapers and sanitary napkins. In the drawing, hot melt pressure-sensitive adhesive 2 is applied to one surface of a long strip-shaped original fabric sheet 1 conveyed in one direction, and another member is applied to the application surface of hot melt pressure-sensitive adhesive 2 in the original fabric sheet 1. 3 shows a process of manufacturing a long band-like joined body 4 by superposing 3 and joining the raw sheet 1 and the member 3 together. This joined body is further subjected to several kinds of processing and joining of other members (not shown), and finally is cut into predetermined joined bodies 5 by being cut into predetermined lengths. Examples of the raw sheet 1 include those used as a top sheet and a back sheet.

  The long strip-shaped original fabric sheet 1 is fed out from a roll (not shown) and conveyed at a predetermined speed in a direction indicated by an arrow A in FIG. A coating device 6a for the hot-melt pressure-sensitive adhesive 2 is disposed on the transported original sheet 1 so as to face the one surface. The coating device 6 a is connected to a supply device 6 b for the hot melt adhesive 2. The hot melt pressure-sensitive adhesive 2 heated to the predetermined viscosity by the supply device 6b is discharged from the coating device 6a and applied to one surface of the original fabric sheet 1. The application pattern of the hot melt pressure-sensitive adhesive 2 is appropriately selected according to the type of the member 3 and the like. For example, a coater-type coating device that coats adhesive from a nozzle in contact with the original fabric sheet can be applied to the entire surface of the original fabric sheet 1 without providing a gap, or from the original fabric sheet. It is also possible to apply in a spiral or ohm-shaped pattern using an application device that applies an adhesive from an air rotary nozzle installed at a spaced position. It can also be applied in a striped or beaded pattern. The application amount of the hot melt pressure-sensitive adhesive 2 is appropriately selected according to the type of the raw fabric sheet 1 and the member 3 and the like.

  Application | coating of the hot-melt adhesive 2 is performed in the state in which the original fabric sheet 1 was wound around the roll 7, or in the state before being wound. When coating is performed in a state where the original sheet 1 is wound around the roll 7, the original sheet 1 is supported by the roll 7 from the back surface (that is, the surface opposite to the coating surface). Can be applied more stably.

  The original fabric sheet 1 coated with the hot melt pressure-sensitive adhesive 2 on one side is continuously conveyed and joined with another member 3 conveyed in the same direction as the conveying direction, and both are joined. As the other member 3, a raw fabric sheet having the same or different width as that of the raw fabric sheet 1, or a strand-like member such as rubber thread is used, but is not limited thereto. Joining is performed by the original fabric sheet 1 and the member 3 passing between the pair of nip rolls 8a and 8b. By passing the raw sheet 1 and the member 3 between the nip rolls 8a and 8b, these are sandwiched and a long strip-shaped laminate 4 is obtained. In addition, in FIG. 1, although the state which the other member 3 consists of an elongate continuous body is shown, the form of the other member 3 is not restricted to this. For example, a sheet-like member for each leaf may be used as the other member 3, and the other sheet-like member for each leaf may be intermittently joined to the original fabric sheet 1. Moreover, even if it joins the member which consists of another continuous body or a discontinuous body between the raw fabric sheet 1 and the other member 3 (regardless of whether it is a continuous body or a thing of every leaf). Good. Furthermore, the member which consists of another continuous body or a discontinuous body in the surface on the opposite side to the joining surface with the other member 3 (whether it is a continuous body or the thing of every leaf) in the original fabric sheet 1 May be merged.

  The long strip-shaped laminate 4 is conveyed, and if necessary, several kinds of processing such as heat sealing, ultrasonic sealing, folding processing and joining of other members are added (not shown), and the rotary die cutter 9a. And an anvil roll 9b. The rotary die cutter 9a is provided with one or more cutting blades extending in the axial direction of the roll on its peripheral surface. The anvil roll 9b is a roll having a smooth surface and functions as a receiving roll for a cutting blade provided in the rotary die cutter 9a. In the cutting part 9, the processed laminate 4 ′ is cut across the width direction for each predetermined length along the conveying direction. Thereby, individual laminates 5 are obtained.

  Each laminated body 5 is discriminated into a non-defective product 5a and a defective product 5b in a discriminating section 10 installed downstream of the cutting section 9. In the distinction section 10, a discharge device for the defective product 5b in which a defect is detected is installed. The discharge device is configured to discharge the defective product 5b out of the conveyance path in accordance with a command issued from a control unit 32 (see FIG. 3) described later. As the discharging device, the same one as that conventionally used for manufacturing this type of product can be used. For example, the discharge device includes an air cylinder 10a and a discharge plate 10b attached to the tip of a piston in the air cylinder 10a. The discharge plate 10 b is installed above the transport path of the stacked body 5. A pivot 10c extending in a direction perpendicular to the transport direction is attached to the discharge plate 10b in the central region in the transport direction of the stacked body 5. Moreover, the tip of the piston of the air cylinder 10a is attached to the discharge plate 10b in the upstream end region in the transport direction of the laminate 5. And by the action | operation of the air cylinder 10a, the discharge | emission board 10b can be rotated forward / reversely around the axis 10c. In the distinctive section 10, the laminated body 5 is transported with a belt sandwiched between the top and bottom in the transport direction. The lower belt is divided at a distance shorter than the length of the laminated body 10 in the transport direction to form a discharge port D. When the defective product 5b has been conveyed to the distinction portion 10, the piston of the air cylinder 10a is drawn into the cylinder, whereby the discharge plate 10b rotates counterclockwise around the pivot 10c, blocking the conveyance system path, By dropping the defective product 5b into the discharge port D, the defective product 5b is discharged out of the conveyance path.

  FIG. 2 shows a main part near the roll 7 in FIG. FIG. 3 is a schematic diagram of FIG. For convenience, FIGS. 2 and 3 do not show the application device 6a and the supply device 6b for the hot melt adhesive. In FIG. 3, the hatched portion of the original fabric sheet 1 means a portion where a hot melt adhesive is applied.

  The roll 7 is installed in the middle of the conveying path of the original sheet 1 so that the axial direction thereof is orthogonal to the conveying direction A of the original sheet 1. An axis of the roll 7 is supported by a support structure (not shown), and is rotatable in the transport direction A. An original sheet 1 is wound around the peripheral surface of the roll 7 as shown in the figure. The degree of winding of the original sheet 1 is such that the angle θ (see FIG. 4) from the center of the roll 7 is 20 degrees or more, and 30 in order to keep the original sheet 1 in close contact with the roll 7 at all times. It is preferable that the angle is not less than 180 degrees and not more than 180 degrees. Specifically, it is preferable to set the angle to 20 degrees or more and 180 degrees or less, particularly 30 degrees or more and 180 degrees or less. Further, the tension of the original sheet 1 wound around the roll 7 may be such that the original sheet 1 does not float from the peripheral surface of the roll 7. In the present embodiment, a portion of the raw sheet 1 that is wound around the roll 7 is used as the inspected portion 20. Then, in the inspected part 20, it is detected whether or not there is a foreign substance in the conveyed original sheet 1. In addition, the foreign matter may be located on the surface of the original fabric sheet 1, on the inside of the original fabric sheet 1, or on both. In the present invention, foreign matter can be detected in any of these cases. The foreign matter may be colored and opaque, or colorless or colored, transparent or translucent. It is one of the features of the present invention that foreign matter can be detected even when the foreign matter is colorless or colored, transparent or translucent.

  As shown in FIG. 2, an optical device 22 having a projector and a light receiver is installed on the first side edge 11 side of the original fabric sheet 1. The projector of the optical device 22 irradiates incident light using laser light as a light source parallel to the axial direction of the roll 7 and from the first side edge 11 to the second side edge 12 of the original fabric sheet 1. It is configured to be possible. Specifically, the projector of the optical device 22 can irradiate incident light to the inspected portion 20 of the original fabric sheet 1 or a space in the vicinity thereof in parallel to the axial direction of the roll 7. As shown in FIG. 3, the incident light is irradiated so as to cross a region of the raw sheet 1 to which the hot melt adhesive is applied (that is, a hatched region in FIG. 3). On the other hand, the light receiver of the optical device 22 is configured to be able to measure the amount of reflected light received later. In addition, as the optical device 22 having a projector and a light receiver, commercially available products such as a sensor generally referred to as a retroreflective type, for example, LV-S61 manufactured by Keyence and E3C-LR11 manufactured by OMRON can be used.

  In general, in an absorbent article manufacturing apparatus, a manufacturing line extends in one direction, and one side is referred to as an operation side and the other side is referred to as an apparatus side across the manufacturing line. An operator of the production line can be arranged on the operation side, so that the production line can be easily operated and maintained. On the equipment side, a wall portion for fixing each device of the production line and a drive source for driving each device are installed, and an operator cannot be arranged during normal operation. In such a manufacturing apparatus, it is preferable to arrange the optical device 22 on the operation side because the adjustment and maintenance of the optical device 22 can be easily performed.

  As the projector of the optical device 22, various laser light sources can be used. Laser light is a suitable light source because it has the property of easily narrowing the luminous flux, and thus increases the sensitivity of detecting minute foreign matter. In the present embodiment, laser light having a wavelength in the visible light region, for example, red laser light can be used. On the other hand, as the light receiver of the optical device 22, for example, a charge coupled device or the like can be used. As the light source of the red laser light, it is preferable to use a laser diode that oscillates a red visible laser in the range of 635 nm to 690 nm, for example.

  The optical device 22 is installed at the outer side in the width direction of the roll 7 on the first side edge 11 side of the original fabric sheet 1. The optical device 22 is attached to a support structure including a support column 24 fixed in the vertical direction. This support structure is a structure different from the support structure (not shown) of the roll 7. Therefore, the installation position of the optical device 22 can be adjusted vertically and horizontally independently of the installation position of the roll 7.

  A reflecting mirror 26 is installed on the second side edge 12 side of the raw sheet 1. The reflecting mirror 26 is installed so that the reflected light passes through the same optical path as the incident light irradiated from the projector of the optical device 22.

  The reflecting mirror 26 is installed at the outer side in the width direction of the roll 7 on the second side edge 12 side of the original fabric sheet 1. In addition, the reflecting mirror 26 is attached to a support structure including a support column 28 fixed in the vertical direction. This support structure is a structure different from the support structure (not shown) of the roll 7. Therefore, the installation position of the reflecting mirror 26 can be adjusted vertically and horizontally independently of the installation position of the roll 7. Incident light from the projector of the optical device 22 is reflected by the reflecting mirror 26 and is received by the light receiver of the optical device 22 as reflected light.

  When the received light amount of the reflected light is measured by the light receiver of the optical device 22, the received light amount data is sent to the determination unit 30. In the determination unit 30, it is determined whether or not foreign matter exists on the surface of the original sheet 1 based on the received light amount data transmitted from the light receiver of the optical device 22. The determination result is sent to the control unit 32. When the determination that there is a foreign object is sent to the control unit 32, the control unit 32 is directed to the defective part 5b (see FIG. 1) at a timing based on the distance between the inspected part 20 and the distinctive part 10. (See Fig. 1). Upon receiving the discharge command, the distinction unit 10 operates the air cylinder 10a (see FIG. 1). The determination unit 30 and the control unit 32 are generally composed of electronic circuits. The determination unit 30 and the control unit 32 may be used as separate devices, or both the determination unit 30 and the control unit 32 may be incorporated into one device.

  As shown in FIG. 2, in the vicinity of the optical device 22, an injection unit 34 that blows air on the light receiver and the light receiving surface of the optical device 22 is provided. The ejection unit 34 prevents dust generated due to the conveyance of the original fabric sheet 1 and the like, the scattered and solidified material of the hot melt pressure-sensitive adhesive, and the like from adhering to the light receiver. Used to remove. For this purpose, the air flow is jetted continuously or intermittently at intervals from the jet section 34. In FIG. 2, the injection unit 34 is provided only in the light receiver of the optical device 22, but for the same purpose, it may be injected into the light projector. Alternatively, the reflecting mirror 26 may be provided with an ejection unit that blows air onto the reflecting mirror 26.

  The foreign matter inspection method using the apparatus having the above configuration will be described. First, at the position of the roll 7 or a position upstream thereof, the hot melt adhesive is applied to one surface of the original fabric sheet 1 by the application device 6a. Part is formed. Next, the raw fabric sheet 1 wound around the roll 7 is irradiated with incident light on the inspected portion 20 including the coating portion or a space in the vicinity thereof. FIG. 4A shows an example of the irradiation state of the incident light B1. When the incident light B1 is irradiated on the inspected portion 20, a part of the incident light B1 is irradiated into the original sheet 1, and in some cases, the other part is along the surface of the original sheet 1. To irradiate the space on the surface. On the other hand, when the incident light B <b> 1 is irradiated in the vicinity of the inspected part 20, the incident light B <b> 1 travels in the space on the surface of the original fabric sheet 1 and does not travel in the original fabric sheet 1. In any case, the incident light B1 is irradiated in parallel with the axial direction of the roll 7. In FIG. 4A, the hatched portion indicates the range in which the original sheet 1 is wound around the roll 7 (the same applies to FIGS. 4B and 4C described later). is there.). The irradiated incident light B1 is reflected by a reflecting mirror (not shown), and returns through an optical path substantially the same as the optical path of the incident light B1. The returned reflected light is received by the light receiving unit of the optical device 22. When no foreign matter is present on the original fabric sheet 1, the amount of reflected light received does not change. On the other hand, when the foreign material exists on the raw sheet 1, the incident light B1 is blocked by the foreign material, and the amount of the incident light B1 reaching the reflecting mirror 26 is reduced. Moreover, even when the reflected light reflected by the reflecting mirror 26 returns to the light receiving unit of the optical device 22, the reflected light is blocked by the foreign matter, and the amount of reflected light reaching the light receiving unit is reduced. As a result, when foreign matter exists on the original fabric sheet 1, the amount of light received by the light receiving unit of the optical device 22 is lower than when no foreign matter exists on the original fabric sheet 1. When the decrease in the amount of light exceeds the threshold value, the determination unit 30 (see FIG. 3) described above determines that there is a foreign substance in the original fabric sheet 1, and the determination result is displayed on the control unit 32 (see FIG. 3). ) Upon receiving the determination result, the control unit 32 sends a defective product discharge command to the distinction unit 10 at a timing based on the distance between the inspected unit 20 and the distinction unit 10, and the distinction unit 10 that has received the discharge instruction receives the discharge command. When the defective product arrives at the distinction section 10, the air cylinder 10a (see FIG. 1) is operated to discharge the defective product out of the conveyance path.

  The surface of the original fabric sheet 1 means that the original fabric sheet 1 is made of a fiber sheet such as a non-woven fabric and has a fluff of fibers, that is, a position not including the fluff, that is, a sheet on the fluff base side. It means a surface. Moreover, the vicinity of the surface of the raw fabric sheet 1 means a space separated from the surface by a distance of 3 mm or less. This distance is the distance between the sheet-side edge of incident light and reflected light and the surface of the original sheet 1.

  According to the above detection method, when foreign matter exists on the original sheet 1, that is, when an object exists on the surface or inside of the original sheet 1, incident light and reflected light are blocked by the foreign matter. There is an advantage that the detection sensitivity can be easily increased. Further, since foreign matter can be detected only by using the optical device 22 and the reflecting mirror 26, unlike the Patent Document 3 described above, it is not necessary to use two pairs of detection devices that are paired with a projector and a light receiver. This is advantageous because only one adjustment of the optical axis is required. Further, it is advantageous in that the installation space for the apparatus can be made compact. In particular, when the detection devices are installed at a plurality of locations on the absorbent article production line, it is extremely advantageous to be able to make the installation space compact.

  Furthermore, according to the above detection method, the foreign matter can be detected with a constant sensitivity regardless of the position of the foreign matter in the width direction of the original fabric sheet 1. This is because incident light and its reflected light are used to detect foreign matter. In addition, since the portion of the original sheet 1 that is wound around the roll 7 is used as the detected portion 20, the original sheet 1 is backed up by the roll 7. Shake is less likely to occur. Therefore, the foreign object can be detected stably.

  In addition, according to the detection method described above, before the other member 3 is superimposed on the hot melt pressure-sensitive adhesive application surface of the raw sheet 1, foreign matter caused by the hot-melt pressure-sensitive adhesive, for example, hot-melt pressure-sensitive adhesive Since the solidified or semi-solidified mass due to the agent is detected, the detection can be easily performed. From the same point of view, after the hot melt pressure-sensitive adhesive 2 is applied to the raw sheet 1, a post-process such as a bending process is applied to the raw sheet 1 to cover the application surface of the hot melt pressure-sensitive adhesive. Even in such a case, foreign matter can be detected before such a post-process is performed.

  In the above detection method, as the raw fabric sheet 1, various non-woven fabrics and resin films used as a top sheet and a back sheet of an absorbent article are used. When a nonwoven fabric is used as the raw fabric sheet 1, the surface of the nonwoven fabric generally has fuzz due to its constituent fibers, but the variation in the amount of received light is caused by the amount of received light by the foreign object to be detected by this detection method. This level is negligible for fluctuations.

  The incident light B1 emitted from the projector of the optical device 22 can have a light beam having a spot shape (beam shape) as shown in FIG. Instead of this, as shown in FIG. 4B, the light beam of the incident light B <b> 2 can have an elongated shape (slit shape) extending in the radial direction of the roll 7. In either case, the incident light B2 passes through both the surface of the original sheet 1 (including the inside of the original sheet 1) and its vicinity.

  FIG. 4C shows another irradiation state of incident light. In this figure, similar to FIG. 4A, the incident light B3 in which the light beam is spot-shaped (beam-shaped) is irradiated. However, in FIG. 4C, unlike FIG. 4A, the incident light B3 passes through the inspected portion 20 (that is, the interior of the original fabric sheet 1 and possibly the space near the surface of the original fabric sheet 1). Instead, it passes only through a space spaced from the sheet surface of the part 20 to be inspected. Therefore, the reflected light also passes only through a space spaced from the sheet surface of the part 20 to be inspected. This space is in the vicinity of the inspected portion 20, that is, in the vicinity of the surface of the raw sheet 1. The installation position of the projector or reflecting mirror 26 of the optical device 22 is adjusted so as to have such an optical path. By setting the optical path of the incident light B3 and the reflected light in this way according to the size of the foreign object to be detected, the roll sheet 7 is caused to move in the radial direction due to vibration or the like during the conveyance of the original sheet 1. Even when inevitable shakes occur along the way, or even when the raw sheet 1 has uneven basis weight, foreign matters can be reliably detected without being affected by such shakes and unevenness. From this point of view, the lower limit value of the distance d (see FIG. 4C) between the surface of the original fabric sheet 1 in the inspected portion 20 and the beam of incident light B3 is the roll runout amount and the original fabric sheet. Considering the thickness unevenness of 1, it is preferable to set the distance more than the maximum value of the surface runout amount and the sheet thickness. The upper limit value of the distance d is preferably set to be equal to or less than the height of the foreign matter to be discharged, and more preferably half or less of the height of the foreign matter to be discharged.

  4 (a) to 4 (c), the incident light and the optical path of the reflected light are the positions of the optical device 22 supported by the support column 24 and the reflection mirror 26 supported by the support column 28. Although it can be easily adjusted by changing the position, the size of the reflecting mirror 26 is usually sufficiently larger than the spot diameter of the laser, and therefore the position of the optical device 22 may be adjusted. Moreover, since the adjustment of these positions can be performed separately from the adjustment of the installation position of the roll 7, it can adjust easily.

  Further, in any case of FIGS. 4A to 4C, while the original sheet 1 is being conveyed, an air flow is jetted from the jetting unit 34 continuously or intermittently, It is preferable to keep the light projector and light receiver of the optical device 22 in a clean state from the viewpoint of achieving more accurate detection. Similarly, in the case where an injection unit for injecting an air flow is provided in the reflecting mirror 26, it is preferable to inject the air flow toward the reflecting mirror 26 continuously or intermittently.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, although the said embodiment is an example which applied this invention to the manufacturing method of an absorbent article, this invention can be similarly applied to manufacture of another product.

  Further, between the position where the hot melt pressure-sensitive adhesive is applied to the original sheet 1 and the detected portion 20, it is directed in the same direction as the laser light irradiation direction and at the surface of the original sheet 1 or in the vicinity thereof. Air may be jetted to blow off and remove foreign matter present in the original fabric sheet 1. By performing such an operation, generation of defective products can be suppressed.

  In addition, an injection unit capable of injecting air at a position after the detected portion 20 in the same direction as the laser light irradiation direction and on the surface of the raw sheet 1 or in the vicinity thereof is installed. When a foreign matter is detected on the raw fabric sheet 1 in the detected portion 20, the foreign matter may be removed by blowing air toward the foreign matter when the foreign matter passes through the ejecting portion. The occurrence of defective products can also be suppressed by performing such an operation. When performing this operation, it is preferable to detect whether or not foreign matter is present again at a position after the ejection unit.

  The present invention further discloses the following foreign substance inspection method and foreign substance inspection apparatus with respect to the above-described embodiments.

<1> A foreign matter inspection method for detecting whether or not foreign matter is present in a long belt-like sheet to be conveyed,
Wrap the sheet on a roll installed in the middle of its transport path,
Of the sheet, a laser beam is directed to the inspected portion formed of a portion wound around the roll or in the vicinity thereof, parallel to the axial direction of the roll and from one side edge to the other side edge of the sheet. Irradiate incident light as a light source,
Reflecting the incident light by a reflector installed on the other side edge so that the reflected light passes through the same optical path as the incident light,
The returned reflected light is received by a light receiver installed on the side edge, and the amount of the reflected light received is measured.
A foreign matter inspection method for inspecting whether or not foreign matter exists on the sheet based on the amount of the received light.

<2> The inspection method according to <1>, wherein the incident light and the reflected light pass through a position separated from the part to be inspected.
<3> The inspection method according to <1> or <2>, wherein the inspection is performed while blowing air to the light receiver or the reflecting mirror.
<4> After applying a hot melt pressure-sensitive adhesive on one surface of the sheet to form an application portion, the region of the sheet including the application portion is set as the inspection portion, and the solidification or half caused by the hot melt pressure-sensitive adhesive The inspection method according to any one of <1> to <3>, wherein the solidified block is detected as a foreign substance.
<5> The inspection method according to any one of <1> to <4>, wherein the sheet is a top sheet or a back sheet of an absorbent article.

<6> The inspection method according to any one of <1> to <5>, wherein the foreign matter is transparent or translucent.
<7> After the hot melt pressure-sensitive adhesive is applied to the sheet, irradiate incident light on the inspected part including the application part of the hot melt pressure adhesive or the vicinity thereof,
Application | coating of the said hot melt adhesive is an inspection method of any one of said <1> thru | or <6> performed in the state in which the said sheet | seat was wound around the said roll.
<8> After the hot melt pressure-sensitive adhesive is applied to the sheet, incident light is irradiated on or near the inspected part including the hot melt pressure-sensitive adhesive application part, and then the hot melt pressure-sensitive adhesive is applied. The inspection method according to any one of <1> to <7>, wherein the sheet is continuously conveyed, merged with another member conveyed in the same direction as the conveyance direction, and joined together.

<9> The inspection method according to <8>, wherein a long strip-shaped laminate is obtained by the bonding.
<10> The long strip-shaped laminate is transported, and the long strip-shaped laminate is cut across the width direction for each predetermined length along the transport direction, thereby obtaining individual laminates <9 > Inspection method.
<11> The inspection method according to <10>, wherein each of the laminated bodies obtained by cutting is discriminated into a non-defective product and a defective product in a discriminating portion.
<12> When it is determined that foreign matter exists on the sheet based on the amount of the received light, a defective product discharge command is issued to the distinction portion at a timing based on the distance between the inspected portion and the distinction portion. The inspection method according to <11>, which is sent.

<13> The inspection method according to <11> or <12>, wherein the defective products that have been distinguished are discharged out of a conveyance path.
<14> The degree of winding of the sheet around the roll is such that the angle θ from the center of the roll is 20 degrees or more, further 30 degrees or more and 180 degrees or less, particularly 20 degrees or more and 180 degrees. In the following, the inspection method according to any one of <1> to <13>, wherein the inspection method is set to an extent of 30 degrees to 180 degrees.
<15> After the hot melt pressure-sensitive adhesive is applied to the sheet, the incident light is irradiated so as to cross the application part of the hot melt pressure-sensitive adhesive. Inspection method.
<16> The inspection method according to any one of <1> to <15>, wherein it is detected whether foreign matter is present on the surface of the sheet.

<17> After the hot melt pressure-sensitive adhesive is applied to the sheet, irradiate incident light on the inspected part including the hot melt pressure-sensitive adhesive application part or in the vicinity thereof,
The inspection method according to any one of <1> to <16>, wherein the solidified or semi-solidified mass due to the hot melt pressure-sensitive adhesive is detected as the foreign matter.
<18> The inspection method according to any one of <1> to <17>, wherein the sheet is a nonwoven fabric or a resin film.
<19> The inspection method according to any one of <1> to <18>, wherein the spot-shaped or slit-shaped incident light is irradiated.

<20> A method for manufacturing an absorbent article that includes the inspection method according to any one of <1> to <19> in a manufacturing process of an absorbent article, and discharges defective products including foreign matters.

<21> A foreign matter inspection apparatus for detecting whether or not foreign matter is present in a long belt-like sheet to be conveyed,
A roll installed in the middle of the sheet conveyance path so that the axial direction is orthogonal to the sheet conveyance direction;
Of the sheet, a laser beam is directed to the inspected portion formed of a portion wound around the roll or in the vicinity thereof, parallel to the axial direction of the roll and from one side edge to the other side edge of the sheet. A projector capable of irradiating incident light as a light source and installed on the side edge;
A reflecting mirror installed on the side of the other side edge so that the reflected light passes through the same optical path as the optical path of the incident light;
It is possible to receive the reflected light that has returned and measure the amount of the reflected light received, and a light receiver installed on the one side edge;
A foreign matter inspection apparatus comprising: a determination unit that determines whether or not a foreign matter is present on the sheet based on received light amount data sent from the light receiver.

<22> The light projector, the light receiver, or the reflecting mirror is supported by a support structure different from the support structure of the roll, and the installation position of the light projector, the light receiver, or the reflective mirror is set to the position of the roll. The device according to <21>, wherein the device can be adjusted separately from the position.
<23> The apparatus according to <21> or <22>, wherein an injection unit that blows air on the light receiver or the reflecting mirror is provided.
<24> The projector is capable of irradiating a laser beam,
<21> to <23>, wherein an installation position of the projector or the reflecting mirror is adjusted so that the incident light and the reflected light pass through a position separated from the surface of the inspected part. The apparatus of any one.

<25> The apparatus is used for manufacturing absorbent articles,
In the apparatus, the production line extends in one direction, one side is the operation side across the production line, the other side is the equipment side,
An operator of the production line can be arranged on the operation side,
A drive source is installed on the device side,
The apparatus according to any one of <21> to <24>, wherein the projector and the light receiver are arranged on the operation side.
<26> When the foreign matter is present on the sheet, incident light is blocked by the foreign matter, the amount of incident light reaching the reflecting mirror is reduced, and the reflected light reflected by the reflecting mirror is received by the light receiving device. When returning to the part, the reflected light is blocked by the foreign matter, and the amount of the reflected light reaching the light receiving part is reduced to any one of the above items <21> to <25> The device described.
<27> A method for manufacturing an absorbent article, wherein the foreign substance inspection device according to any one of <21> to <26> is installed in a production line for absorbent articles, and defective products containing foreign substances are discharged.

DESCRIPTION OF SYMBOLS 1 Long strip | belt-shaped sheet | seat 2 Hot melt adhesive 3 Other members 4 Long strip | belt-shaped laminated body 7 Roll 20 Detected part 22 Optical apparatus 26 Reflecting mirror

Claims (9)

A foreign matter inspection method for detecting whether or not foreign matter is present in a long belt-like sheet to be conveyed,
Wrap the sheet on a roll installed in the middle of its transport path,
Of the sheet, a laser beam is directed to the inspected portion formed of a portion wound around the roll or in the vicinity thereof, parallel to the axial direction of the roll and from one side edge to the other side edge of the sheet. Irradiate incident light as a light source,
Reflecting the incident light by a reflector installed on the other side edge so that the reflected light passes through the same optical path as the incident light,
The returned reflected light is received by a light receiver installed on the side edge, and the amount of the reflected light received is measured.
A foreign matter inspection method for inspecting whether or not foreign matter exists on the sheet based on the amount of the received light.   The inspection method according to claim 1, wherein the incident light and the reflected light pass through a position separated from the part to be inspected.   The inspection method according to claim 1, wherein the inspection is performed while blowing air to the light receiver or the reflecting mirror.   A hot melt pressure-sensitive adhesive is applied to one surface of the sheet to form an application portion, and then the region of the sheet including the application portion is used as the inspected portion, and a solidified or semi-solidified mass resulting from the hot melt adhesive The inspection method according to any one of claims 1 to 3, wherein the method is detected as a foreign object.   The inspection method according to any one of claims 1 to 4, wherein the sheet is a top sheet or a back sheet of an absorbent article. A foreign matter inspection apparatus for detecting whether foreign matter is present in a long belt-like sheet to be conveyed,
A roll installed in the middle of the sheet conveyance path so that the axial direction is orthogonal to the sheet conveyance direction;
Of the sheet, a laser beam is directed to the inspected portion formed of a portion wound around the roll or in the vicinity thereof, parallel to the axial direction of the roll and from one side edge to the other side edge of the sheet. A projector capable of irradiating incident light as a light source and installed on the side edge;
A reflecting mirror installed on the side of the other side edge so that the reflected light passes through the same optical path as the optical path of the incident light;
It is possible to receive the reflected light that has returned and measure the amount of the reflected light received, and a light receiver installed on the one side edge;
A foreign matter inspection apparatus comprising: a determination unit that determines whether or not a foreign matter is present on the sheet based on received light amount data sent from the light receiver.   The light projector, the light receiver or the reflecting mirror is supported by a support structure different from the support structure of the roll, and the installation position of the light projector, the light receiver or the reflection mirror is different from the installation position of the roll. 7. The device according to claim 6, wherein the device is adjustable.   The apparatus of Claim 6 or 7 with which the injection part which blows air on the said light receiver or the said reflective mirror is provided. The projector is capable of irradiating a laser beam,
9. The installation position of the projector or the reflecting mirror is adjusted so that the incident light and the reflected light pass through a position separated from the surface of the inspected part. The device according to item.

Images