Corrugated board defect detection device and method and box making machine

Abstract

A corrugated board defect detection device and method and a box making machine, in a corrugated board defect detection device in which a recess of a first rule is formed on one side in the thickness direction, and a recess of a second rule having a smaller depth than the recess of the first rule is formed on the other side in the thickness direction, the device comprising: a measuring device configured to measure and acquire, as a measured distance, a distance from a position of the measuring device to a top end of the corrugated board and a distance to the recess of the first rule or the recess of the second rule; a storage device that stores a threshold value set in advance; and a determination device that compares the measured distance with the threshold value in a predetermined determination region set in advance from the top end of the corrugated board toward the rear end, thereby determining a size relationship between the measured distance and the threshold value, and determining a front-back defect or a face-back defect of the corrugated board.

Description

Technical Field

[0001] This disclosure relates to a defect detection device and method for corrugated board, which determines the orientation defects of corrugated board during its conveying process, as well as a box-making machine. Background Technology

[0002] The corrugated board manufacturing apparatus processes the core paper into a corrugated shape and laminates it with a backing board to form single-faced corrugated board. A face liner is then laminated onto the single-faced corrugated board to form double-faced corrugated board. The double-faced corrugated board is cut to a specified width and length, thus becoming a sheet of corrugated board. Furthermore, the corrugated board manufacturing apparatus finally forms grid lines on the corrugated board for forming flaps.

[0003] A box-making machine manufactures boxes (corrugated cartons) by processing corrugated cardboard produced by a corrugated cardboard manufacturing unit. Specifically, the box-making machine prints on the surface of the corrugated cardboard, forming grid lines that act as fold lines, and processes the cardboard to form grooves for flaps and adhesive sheets for joining. The corrugated cardboard with the grid lines and grooves is then coated with adhesive sheets and folded to form a flat corrugated carton.

[0004] A corrugated board manufacturing apparatus laminates a backing board, a corrugated core paper, and a face liner in layers to produce corrugated board. The corrugated board is conveyed with the backing board facing upwards. Conversely, in a carton-making machine, the corrugated board is conveyed with the face liner facing upwards to produce a flat corrugated carton. In both the corrugated board manufacturing apparatus and the carton-making machine, the conveying directions of the corrugated board differ by 90 degrees horizontally. Furthermore, in both apparatuses, the face and back of the corrugated board are reversed during conveying. Therefore, the corrugated board manufactured by the corrugated board manufacturing apparatus is fed to the carton-making machine after its conveying direction has been changed and its face and back reversed.

[0005] Therefore, when corrugated cardboard is supplied to the box-making machine, the conveying direction and the front and back sides are sometimes not properly changed. For example, sometimes the conveying direction of the corrugated cardboard is reversed or the front and back sides are reversed. As a technique for detecting defects in the orientation of the conveying direction of the corrugated cardboard, there is, for example, the technique described in Patent Document 1 below.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2021-115839 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] The defect detection method described in Patent Document 1 detects the top of the corrugated cardboard and the recesses of the grid lines. It converts the conveying time from detecting the top of the corrugated cardboard to detecting the recesses of the grid lines into the distance between the top of the corrugated cardboard and the recesses of the grid lines, and determines whether the recesses of the grid lines are in the appropriate position. However, while conventional defect detection methods can detect defects in the forward and backward conveying direction of the corrugated cardboard, they have the problem of not being able to detect defects such as the front and back sides being reversed.

[0011] This disclosure is an invention to solve the above-mentioned problems, and its object is to provide a defect detection device and method for corrugated board that can properly detect the conveying condition of corrugated board, as well as a box-making machine.

[0012] Technical solution

[0013] The present disclosure of a defect detection device for corrugated cardboard, which achieves the above-mentioned objectives, is a device for detecting defects in corrugated cardboard having a first grid line recess formed on one side in the thickness direction and a second grid line recess with a depth smaller than the first grid line recess formed on the other side in the thickness direction. The device comprises: a measuring device configured to face the first or second side, measuring and acquiring a distance from the configured position to the top of the corrugated cardboard and a distance to the first or second grid line recess as a measuring distance; a storage device for storing a preset threshold; and a determination device that compares the measuring distance with the threshold in a preset determination area from the top of the corrugated cardboard toward the rear end, thereby determining the relationship between the measuring distance and the threshold, and determining that the corrugated cardboard has surface / back defect or front / back defect.

[0014] Furthermore, the defect detection method for corrugated cardboard disclosed herein is a method for detecting defects in corrugated cardboard in which a first grid line recess is formed on one side in the thickness direction and a second grid line recess with a depth smaller than the first grid line recess is formed on the other side in the thickness direction. This method includes the following steps: measuring and obtaining a distance from a predetermined position opposite to the first or second grid line to the top of the corrugated cardboard and a distance to the recess of the first or second grid line as a measurement distance; comparing the measurement distance with a predetermined threshold in a predetermined determination area from the top of the corrugated cardboard toward the rear end; and determining the relationship between the measurement distance and the threshold to determine whether the corrugated cardboard has surface / back defect or front / back defect.

[0015] Furthermore, the box-making machine disclosed herein is equipped with a defect detection device for the corrugated cardboard.

[0016] Invention Effects

[0017] According to the defect detection apparatus and method for corrugated cardboard and the box-making machine disclosed herein, defects in the conveying condition of corrugated cardboard can be appropriately detected. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a corrugating machine.

[0019] Figure 2 This is a top view of corrugated cardboard produced by a corrugating machine.

[0020] Figure 3 This is a schematic diagram of a box-making machine.

[0021] Figure 4 This is a top view of corrugated cardboard manufactured by a box-making machine and before folding.

[0022] Figure 5 This is a schematic diagram showing the configuration of a defect detection device for corrugated cardboard according to the first embodiment.

[0023] Figure 6 This is an illustrative diagram used to explain the defect detection methods for corrugated cardboard.

[0024] Figure 7 This is an explanatory diagram used to illustrate the first threshold and the second threshold.

[0025] Figure 8 This is an explanatory diagram illustrating the detection method for defective corrugated cardboard with the reverse side facing up.

[0026] Figure 9 This is an illustrative diagram used to explain the detection method for defective corrugated cardboard that is upside down.

[0027] Figure 10 This is a flowchart illustrating the judgment and control methods for defect detection of corrugated cardboard.

[0028] Figure 11 This is a schematic diagram showing the configuration of the defect detection device for corrugated cardboard according to the second embodiment.

[0029] Figure 12 This is a flowchart illustrating the judgment and control methods for defect detection of corrugated cardboard. Detailed Implementation

[0030] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to these embodiments. Furthermore, in cases where multiple embodiments are available, embodiments combining various embodiments are also included. Moreover, the constituent elements of the embodiments include elements readily foreseeable by those skilled in the art, substantially identical elements, and elements within the so-called equivalent scope.

[0031] [First Implementation Method]

[0032] Corrugated Machine

[0033] Figure 1 This is a schematic diagram of a corrugating machine.

[0034] like Figure 1 As shown, the corrugating machine (corrugated cardboard manufacturing apparatus) 10 includes a paper tray 11, 12, a single facer 13, a bridge 14, a paper tray 15, 16, a single facer 17, a bridge 18, a paper tray 19, a preheater 20, a glue applicator 21, a double facer 22, a rotary shear 23, a slitter scorer 24, a cutter 25, a defective product discharge device 26, and a palletizer 27.

[0035] The paper feeder 11 holds the roll of paper containing the core paper C1, continuously feeding the core paper C1 by rotating the roll. The paper feeder 12 holds the roll of paper containing the backing board B1, continuously feeding the backing board B1 by rotating the roll. The single-facer 13 processes the core paper C1 into a corrugated shape and laminates it with the backing board B1 to form single-faced corrugated board D1. The bridge 14 temporarily holds the single-faced corrugated board D1 to absorb the speed difference between the single-facer 13 and the double-facer 22.

[0036] The paper feeder 15 holds the roll of paper containing the core paper C2, continuously feeding the core paper C2 by rotating the roll. The paper feeder 16 holds the roll of paper containing the backing board B2, continuously feeding the backing board B2 by rotating the roll. The single-facer 17 processes the core paper C2 into a corrugated shape and laminates it with the backing board B2 to form single-faced corrugated board D2. The bridge 18 temporarily holds the single-faced corrugated board D2 to absorb the speed difference between the single-facer 17 and the double-facer 22.

[0037] The paper feeder 19 holds the roll of paper that holds the face sheet A in a roll shape, and continuously supplies the face sheet A by rotating the roll. The preheater 20 preheats the single-faced corrugated board D1, single-faced corrugated board D2, and face sheet A respectively. The glue coater 21 applies glue to the tops of the core papers C1 and C2 in the single-faced corrugated boards D1 and D2. The double-facer 22 overlaps the single-faced corrugated board D1, single-faced corrugated board D2, and face sheet A, applying pressure and heating simultaneously to form a bonded, continuous composite double-faced corrugated board E.

[0038] During the initial stage of operation, before the bonding stabilizes, the rotary shearing machine 23 cuts the composite double-faced corrugated cardboard E across its entire width or partially across its width. The slitting and creasing machine 24 cuts the composite double-faced corrugated cardboard E along the conveying direction to a specified width and processes the grid lines extending along the conveying direction. The cutting machine 25 cuts the composite double-faced corrugated cardboard E along its width to a specified length. The slitting and creasing machine 24 and the cutting machine 25 form a sheet-like composite double-faced corrugated cardboard F. The defective product discharge device 26 discharges the composite double-faced corrugated cardboard F deemed defective from the conveyor line. The palletizer 27 stacks the composite double-faced corrugated cardboard F deemed acceptable and discharges it as a finished product.

[0039] It should be noted that the above description describes the case where the corrugating machine 10 laminates single-faced corrugated board D1, single-faced corrugated board D2, and face liner A to manufacture composite double-faced corrugated board F. However, the corrugating machine 10 can also laminate single-faced corrugated board D1 or single-faced corrugated board D2 with face liner A to manufacture double-faced corrugated board. Therefore, in the following description, face liner B1 and B2 will be referred to as face liner B, core paper C1 and C2 as core paper C, and composite double-faced corrugated board F and sheet-like double-faced corrugated board will be referred to as corrugated board S.

[0040] Figure 2 This is a top view of corrugated cardboard produced by a corrugating machine.

[0041] like Figure 2 As shown, a sheet-shaped corrugated cardboard S is formed by bonding a face liner A and a back liner B to both sides of a corrugated core paper C in the thickness direction. The corrugating machine 10 conveys the corrugated cardboard S in the conveying direction X. Furthermore, the corrugated cardboard S is conveyed with the back liner B located on the upper surface side in the vertical direction and the face liner A located on the lower surface side in the vertical direction. The corrugating machine 10 forms grid lines 101 and 102 on the corrugated cardboard S.

[0042] Here, in the corrugated cardboard S, from one end ( Figure 2 The length from the left end to grid line 101 is greater than the length from the other end ( Figure 2 The length from the right end of the corrugated board to grid line 102 is shorter. However, the length from one end to grid line 101 and the length from the other end to grid line 102 vary depending on the specifications of the corrugated board S. For example, in the corrugated board S, the length from one end to grid line 101 may be longer than the length from the other end to grid line 102, or the length from one end to grid line 101 may be the same as the length from the other end to grid line 102.

[0043] <Box Making Machine>

[0044] Figure 3This is a schematic diagram of a box-making machine.

[0045] like Figure 3 As shown, the box-making machine 30 includes a paper feeding section 31, a printing section 32, a paper discharging section 33, a punching section 34, a folding and gluing section 35, and a counting and discharging section 36.

[0046] The paper feeding unit 31 feeds corrugated cardboard S sheet by sheet in the horizontal direction at a constant speed. The printing unit 32 performs multi-color printing on the surface of the corrugated cardboard S. The paper discharge unit 33 has the functions of performing grid processing on the corrugated cardboard S, cutting processing on the corrugated cardboard S, and grooving processing on the corrugated cardboard S. The punching unit 34 punches the corrugated cardboard S with hand holes, etc., to form corrugated cardboard S1. The folding and gluing unit 35 folds the corrugated cardboard S1 and joins the two ends in the width direction to form a flat corrugated carton G. The counting and discharge unit 36 ​​counts the corrugated carton G while stacking them, and then discharges them in batches of a predetermined number.

[0047] Figure 4 This is a top view of corrugated cardboard produced by a box-making machine.

[0048] Corrugated cardboard

[0049] Figure 4 This is a top view of corrugated cardboard manufactured by a box-making machine and before folding.

[0050] like Figure 4 As shown, corrugated cardboard S1 is corrugated cardboard S( produced by corrugating machine 10) through box-making machine 30. Figure 4 The double-dotted lines were printed, gridded, cut, grooved, punched, and were in their state before folding.

[0051] The box-making machine 30 conveys corrugated cardboard S(S1) along the Y-direction. Both the X-direction of the corrugated cardboard S from the corrugating machine 10 and the Y-direction of the corrugated cardboard S from the box-making machine 30 are horizontal, but differ by 90 degrees in the horizontal direction. Furthermore, the corrugated cardboard S(S1) is conveyed with the face liner A positioned on the upper surface in the vertical direction and the back liner B positioned on the lower surface in the vertical direction.

[0052] Corrugated cardboard S1 is formed with grid lines 101 and 102 by corrugator 10. Grid lines 101 and 102 are used to fold flaps when assembling corrugated boxes G manufactured by box-making machine 30.

[0053] Corrugated cardboard S1 has cutting lines 111 and grid lines 112, 113, 114, and 115 spaced at predetermined intervals in the width direction relative to the conveying direction Y. On the grid line 101 side, corrugated cardboard S1 has grooves 121, 122, and 123 and notches 124 spaced at predetermined intervals in the width direction relative to the conveying direction Y. Furthermore, on the grid line 102 side, corrugated cardboard S1 has grooves 131, 132, and 133 and notches 134 spaced at predetermined intervals in the width direction relative to the conveying direction Y. Also, corrugated cardboard S1 has hand holes 141 and 142.

[0054] <Defect Detection Device>

[0055] Figure 5 This is a schematic diagram showing the configuration of a defect detection device for corrugated cardboard according to the first embodiment.

[0056] like Figure 5 As shown, the defect detection device 50 is positioned in the box-making machine 30 upstream of the folding and gluing section 35 in the conveying direction Y of the corrugated cardboard S. The defect detection device 50 detects surface and back defects and front and rear defects in the conveyed corrugated cardboard S. The corrugated cardboard S has a grid line 101 formed downstream in the conveying direction Y, and a grid line 102 formed upstream of the grid line 101 in the conveying direction Y. Furthermore, in the corrugated cardboard S, the length from the top Sa to the grid line 101 is La, and the length from the top Sa to the grid line 102 is Lb.

[0057] The grid lines 101 of the corrugated cardboard S are formed into recesses by being clamped and flattened from the thickness direction by a pair of upper and lower rollers in the slitting and pressing machine 24 of the corrugating machine 10. One roller is in a single-ring shape, and the other roller is in a double-ring shape. The corrugated cardboard S is pressed by the single-ring roller and the double-ring roller to form a first grid line 101a on one side and two second grid lines 101b on the other side. That is, the corrugated cardboard S is conveyed in the box-making machine 30 with the backing plate B arranged on one side (lower surface) and the top plate A arranged on the other side (upper surface). Therefore, the corrugated cardboard S has one first grid line 101a formed on the backing plate B on the lower surface and two second grid lines 101b formed on the top plate A on the upper surface. The first grid line 101a and each of the second grid lines 101b are located at a position offset in the conveying direction Y.

[0058] It should be noted that grid lines 101 and 102 have the same shape. Therefore, for grid line 102, a first grid line 102a is formed on the backing plate B on the lower surface, and two second grid lines 102b are formed on the surface liner A on the upper surface.

[0059] The "face-back defect" of corrugated cardboard S refers to the defect where the front and back sides of the corrugated cardboard S are transported in an inverted state. That is, it means that the corrugated cardboard S is transported with the backing board B on the upper surface and the front liner A on the lower surface. In this case, for corrugated cardboard S, the first grid lines 101a and 102a are on the upper surface, and the second grid lines 101b and 102b are on the lower surface. Furthermore, the "front-back defect" of corrugated cardboard S refers to the defect where the top Sa and the rear Sb are transported in an inverted state. That is, it means that the corrugated cardboard S is transported with the rear Sb on the downstream side (top side) and the top Sa on the upstream side (rear side). In this case, for corrugated cardboard S, grid line 102 is on the downstream side, and grid line 101 is on the upstream side. It should be noted that corrugated cardboard S may sometimes experience both face-back and front-back defects simultaneously.

[0060] The defect detection device 50 includes a distance measuring sensor (measuring device) 51, a rotary encoder 52, a judgment device 53, a storage device 54, and a display device 55.

[0061] The distance measuring sensor 51 is configured to face the backing plate B at a predetermined distance away from the backing plate B, which is one side of the corrugated cardboard S being transported, in the thickness direction of the corrugated cardboard S. The distance measuring sensor 51 measures at least the distance to the top edge of the downstream side of the corrugated cardboard S and the distance to the recesses formed on the grid lines 101, 102 of the corrugated cardboard S.

[0062] Distance measuring sensor 51 is a common distance measuring sensor that measures both the distance to the top of the corrugated cardboard S and the distance to the recesses of grid lines 101 and 102. However, distance measuring sensor 51 can also be a different distance measuring sensor that measures both the distance to the top of the corrugated cardboard S and the distance to the recesses of grid lines 101 and 102. Here, the recesses of grid lines 101 and 102 refer to the recesses of the first grid lines 101a and 102a or the recesses of the second grid lines 101b and 102b. For example, distance measuring sensor 51 may acquire the maximum distance from its position to the recesses of the first grid lines 101a and 102a of the corrugated cardboard S or the maximum distance from its position to the recesses of the second grid lines 101b and 102b as the measured distance.

[0063] The distance measuring sensor 51 is positioned on the backing board B side of the corrugated cardboard S at a distance H away from the backing board B. That is, the distance H is the distance from the distance measuring sensor 51 to the plane of the corrugated cardboard S. Therefore, when the distance measuring sensor 51 measures distance H, it means it has measured either the top Sa or the back Sb of the corrugated cardboard S. Furthermore, as described later... Figure 7As shown, the depth of the recesses in the first grid lines 101a and 102a is depth H1, and the depth of the recesses in the second grid lines 101b and 102b is depth H2. The depth H1 of the first grid lines 101a and 102a is greater than the depth H2 of the second grid lines 101b and 102b. That is, the relationship between the depth H1 of the first grid lines 101a and 102a and the depth H2 of the second grid lines 101b and 102b is H1 > H2. Therefore, when the distance measuring sensor 51 measures a distance H+H1 equal to the distance H plus the depth H1, it means it has measured the first grid lines 101a and 102a (depth H1). Furthermore, when the distance measuring sensor 51 measures a distance H+H2 equal to the distance H plus the depth H2, it means it has measured the second grid lines 101b and 102b (depth H2).

[0064] It should be noted that the distance measurement sensor 51 is preferably, for example, a laser displacement meter, but is not limited to a laser displacement meter; it can also be an ultrasonic sensor, etc. Furthermore, the measuring device is not limited to a non-contact sensor; it can also be a contact sensor.

[0065] Distance measurement sensor 51 is connected to determination device 53. Distance measurement sensor 51 outputs the measurement result to determination device 53.

[0066] The rotary encoder 52 functions as a position detector to detect the conveying position of the corrugated cardboard S. For example, the rotary encoder 52 detects the rotational speed and position of a rotating component in a drive unit that conveys the corrugated cardboard S along the conveying direction Y. The rotary encoder 52 is connected to the judgment device 53. The rotary encoder 52 outputs the detection result to the judgment device 53.

[0067] The judgment device 53 compares the measured distance at a predetermined judgment area from the top to the rear end of the corrugated cardboard S in the conveying direction Y with a predetermined threshold, thereby determining the relationship between the measured distance and the threshold, and judging the front and back defects and front and rear defects of the corrugated cardboard S.

[0068] The threshold has a first threshold HA and a second threshold HB. The first threshold HA and the second threshold HB are determined based on the distance H+H1 to the first grid lines 101a and 102a formed on one side of the backing board B of the corrugated cardboard S, and the distance H+H2 to the second grid lines 101b and 102b formed on the other side of the front linerboard A of the corrugated cardboard S. Here, the second threshold HB is smaller than the first threshold HA. That is, since the relationship between the depth H1 of the first grid lines 101a and 102a and the depth H2 of the second grid lines 101b and 102b is H1>H2, the relationship between the first threshold HA and the second threshold HB is HA>HB.

[0069] The determination device 53 compares the measured distance from the distance measuring sensor 51 with the first threshold HA and the second threshold HB to determine whether the corrugated cardboard S has surface defects or front and back defects. Details of the determination method are described later.

[0070] It should be noted that the determination device 53 is a control device, and the control device is a controller. For example, it is implemented by using a CPU (Central Processing Unit) or MPU (Micro Processing Unit) to execute various programs stored in the storage unit by using RAM (Random Access Memory) as the working area.

[0071] Storage device 54 is connected to judgment device 53. Storage device 54 stores a first threshold HA and a second threshold HB. In addition, storage device 54 stores the judgment result of judgment device 53. Display device 55 is connected to judgment device 53. Display device 55 displays the judgment result of judgment device 53. That is, when corrugated cardboard S is judged to be defective, display device 55 displays whether it is a front / back defect or a front / back defect.

[0072] <Defect Detection Methods for Corrugated Cardboard>

[0073] Figure 6 This is an illustrative diagram used to explain the defect detection methods for corrugated cardboard. Figure 7 This is an explanatory diagram used to illustrate the first threshold and the second threshold.

[0074] like Figure 6 As shown, the defect detection method for corrugated cardboard in the first embodiment includes the following steps: measuring and obtaining the distance to the top of the corrugated cardboard S and the distance to the recess of the first grid lines 101a, 102a or the second grid lines 101b, 102b as measurement distances; comparing the measurement distances with a predetermined first threshold HA in predetermined judgment areas A1, A2 from the top of the corrugated cardboard S toward the rear end; comparing the measurement distances with a second threshold HB that is smaller than the first threshold HA in judgment areas A1, A2; and determining the relationship between the measurement distances and the first threshold HA and the second threshold HB to determine the front and back defects and front and back defects of the corrugated cardboard S.

[0075] Specifically, the distance measuring sensor 51 measures the distance to the corrugated cardboard S, acquiring the measured distance of the corrugated cardboard S at least within a judgment area A1 extending La from the top of the conveyed corrugated cardboard S, and outputting it to the judgment device 53. That is, the distance measuring sensor 51 acquires the measured distance regardless of whether there is corrugated cardboard S on the conveyor line of the box-making machine 30.

[0076] At this time, as Figure 6 As shown, when the corrugated cardboard S is conveyed along the conveying direction Y with an appropriate orientation, the top end Sa is located on the downstream side, the rear end Sb is located on the upstream side, the backing plate B is located on the lower surface side, and the front liner A is located on the upper surface side. The distance between the distance measuring sensor 51 and the corrugated cardboard S, for example, is a value outside the measurement range, until the top end Sa of the corrugated cardboard S reaches the measurement position of the distance measuring sensor 51 at a length L0. Then, when the top end Sa of the corrugated cardboard S reaches the measurement position of the distance measuring sensor 51, the distance measuring sensor 51 measures the distance H (measurement distance) of the top end Sa at a length L0 position, measures the distance H+H1 (measurement distance) of the first grid line 101a at a length L1 position from the top end Sa, measures the distance H+H1 (measurement distance) of the first grid line 102a at a length L2 position from the top end Sa, and measures the distance H (measurement distance) of the rear end Sb at a length L3 position. The distance measuring sensor 51 then outputs the measured distance obtained through measurement to the determination device 53. The determination device 53 receives a measurement distance from the distance measurement sensor 51 and a conveying position of the corrugated cardboard S from the rotary encoder 52. That is, the determination device 53 acquires the measurement distance at the position corresponding to the length L1 of the determination area A1, that is, the distance H+H1 of the first grid line 101a, and the measurement distance at the position corresponding to the length L2 of the determination area A2, that is, the distance H+H1 of the first grid line 102a.

[0077] In this case, the determination area A1 is the length of the area extending from the top Sa of the corrugated cardboard S to a length La, taking into account a predetermined allowance value on both the upstream and downstream sides in the conveying direction Y. Similarly, the determination area A2 is the length of the area extending from the top Sa of the corrugated cardboard S to a length Lb, taking into account a predetermined allowance value on both the upstream and downstream sides in the conveying direction Y. It should be noted that, based on the design values ​​associated with the specifications of the corrugated cardboard S, the lengths La from the top Sa to the first grid line 101a and Lb from the top Sa to the first grid line 102a can be predetermined. Therefore, determination areas A1 and A2 can be preset before the measurement performed by the distance measurement sensor 51.

[0078] If the measured distance (here, distance H+H1) at the determination areas A1 and A2 input from the distance measurement sensor 51 is smaller than the first threshold HA and larger than the second threshold HB, then the determination device 53 determines that the corrugated cardboard S has a front and back defect. Furthermore, if the measured distance (here, distance H+H1) at the determination areas A1 and A2 input from the distance measurement sensor 51 is smaller than the second threshold HB, then the determination device 53 determines that the corrugated cardboard S has a front and back defect.

[0079] like Figure 7As shown, the first threshold HA is set to a value Ha equal to 60% to 70% of the depth H1 of the design value of the first grid lines 101a and 102a, calculated as the distance H from the distance measuring sensor 51 to the plane of the corrugated cardboard S (i.e., to the backing board B without the first grid lines 101a and 102a). Furthermore, the second threshold HB is set to a value Hb equal to 20% to 30% of the depth H1 of the design value of the first grid lines 101a and 102a, calculated as the distance H from the distance measuring sensor 51 to the plane of the corrugated cardboard S (i.e., to the backing board B without the first grid lines 101a and 102a). It should be noted that in this case, the depth of the design value can be predetermined according to the specifications of the corrugated cardboard S. Therefore, the first threshold HA and the second threshold HB can be predetermined before the determination performed by the determination device 53.

[0080] That is, when the corrugated cardboard S is conveyed in the conveying direction Y with an appropriate orientation, the judging device 53 judges that the corrugated cardboard S is neither a surface defect nor a front and back defect, and is a qualified product, based on the fact that the measured distance H+H1 at the judging areas A1 and A2 is greater than the first threshold HA.

[0081] Figure 8 This is an explanatory diagram illustrating the detection method for defective corrugated cardboard with the reverse side facing up.

[0082] like Figure 8 As shown, when the corrugated cardboard S is conveyed in opposite directions along the conveying direction Y, the top Sa is located on the downstream side and the rear Sb is located on the upstream side, but the backing board B is located on the upper surface side and the front liner A is located on the lower surface side. Therefore, the distance measuring sensor 51 measures the distance H (measured distance) of the top Sa at length L0, the distance H+H2 (measured distance) of the second grid line 101b at lengths L11 and L12 from the top Sa, the distance H+H2 (measured distance) of the second grid line 102b at lengths L13 and L14 from the top Sa, and the distance H (measured distance) of the rear Sb at length L15. Then, the distance measurement sensor 51 outputs the measured distance at the position corresponding to the lengths L11 and L12 of the judgment area A1, that is, the distance H+H2 of the second grid line 101b, to the judgment device 53, and outputs the measured distance at the position corresponding to the lengths L13 and L14 of the judgment area A2, that is, the distance H+H2 of the second grid line 102b, to the judgment device 53.

[0083] If the measured distance (here, distance H+H2) at the determination areas A1 and A2 input from the distance measurement sensor 51 is smaller than the first threshold HA and larger than the second threshold HB, then the determination device 53 determines that the corrugated cardboard S has a front and back defect. Furthermore, if the measured distance (here, distance H+H2) at the determination areas A1 and A2 input from the distance measurement sensor 51 is smaller than the second threshold HB, then the determination device 53 determines that the corrugated cardboard S has a front and back defect.

[0084] That is, when the corrugated cardboard S is conveyed in the opposite direction along the conveying direction Y, the judgment device 53 determines that the corrugated cardboard S is defective in both the front and back sides because the measured distance H+H2 at the judgment areas A1 and A2 is smaller than the first threshold HA and larger than the second threshold HB.

[0085] Figure 9 This is an illustrative diagram used to explain the detection method for defective corrugated cardboard that is upside down.

[0086] like Figure 9 As shown, when the corrugated cardboard S is conveyed in opposite directions along the conveying direction Y, the top Sa is located on the upstream side, the rear Sb is located on the downstream side, the backing plate B is located on the lower surface side, and the front liner A is located on the upper surface side. Therefore, the distance measuring sensor 51 measures the distance H (measured distance) of the rear Sb at a length L0, the distance H+H1 (measured distance) of the first grid line 102a at a length L21 from the rear Sb, the distance H+H1 (measured distance) of the first grid line 101a at a length L22 from the rear Sb, and the distance H (measured distance) of the top Sa at a length L23. Then, the distance measuring sensor 51 outputs the measured distance at the position corresponding to the determination area A1, i.e., the distance H of the corrugated cardboard S, obtained through measurement, to the determination device 53, and also outputs the measured distance at the position corresponding to the determination area A2, i.e., the distance H of the corrugated cardboard S, to the determination device 53.

[0087] If the measured distance (here, distance H) at the determination areas A1 and A2 input from the distance measurement sensor 51 is smaller than the first threshold HA and larger than the second threshold HB, then the determination device 53 determines that the corrugated cardboard S has a front and back defect. Furthermore, if the measured distance (here, distance H) at the determination areas A1 and A2 input from the distance measurement sensor 51 is smaller than the second threshold HB, then the determination device 53 determines that the corrugated cardboard S has a front and back defect.

[0088] That is, when the corrugated cardboard S is conveyed in opposite directions along the conveying direction Y, the judgment device 53 determines that the corrugated cardboard S has front and back defects because the measured distance H at the judgment areas A1 and A2 is smaller than the second threshold HB.

[0089] Figure 10 This is a flowchart illustrating the judgment and control methods for defect detection of corrugated cardboard.

[0090] like Figure 5 and Figure 10 As shown, in step S11, the determining device 53 determines whether the top edge of the corrugated cardboard S is detected based on information input from the distance measuring sensor 51. Here, the top edge of the corrugated cardboard S is the downstream top edge, which is either the top edge Sa or the rear edge Sb. If the determining device 53 determines that the top edge of the corrugated cardboard S is not detected (No), it continues with the processing of step S11. On the other hand, if the determining device 53 determines that the top edge of the corrugated cardboard S is detected (Yes), it proceeds to step S12.

[0091] In step S12, the determining device 53 acquires the measured distance of the corrugated cardboard S at the determining areas A1 and A2 as measured by the distance measuring sensor 51. In step S13, the determining device 53 determines whether the measured distance is greater than the first threshold HA. If the determining device 53 determines that the measured distance is greater than the first threshold HA (yes), then in step S14, the corrugated cardboard S is determined to be a qualified product.

[0092] On the other hand, if the determining device 53 determines that the measured distance is not greater than the first threshold HA (No), it proceeds to step S15. In step S15, the determining device 53 determines whether the measured distance is greater than the second threshold HB. If the determining device 53 determines that the measured distance is greater than the second threshold HB (Yes), it determines in step S16 that the corrugated cardboard S is a defective product with a poor front and back.

[0093] On the other hand, if the determination device 53 determines that the measured distance is not greater than the second threshold HB (no), then in step S17 it determines that the corrugated cardboard S is a defective product, which is defective both before and after.

[0094] It should be noted that in the above description of the determination method, two determination regions A1 and A2 are set, and the measured distances measured in each determination region A1 and A2 are compared with the first threshold HA and the second threshold HB to determine the defect. However, it is sufficient to determine the defect by comparing the measured distance with the first threshold HA and the second threshold HB in at least one of the two determination regions A1 (A2).

[0095] [Second Implementation]

[0096] Figure 11 This is a schematic diagram illustrating the defect detection device for corrugated cardboard according to the second embodiment. It should be noted that components having the same functions as those in the above-described embodiment are labeled with the same reference numerals, and detailed descriptions are omitted.

[0097] The defect detection device 50A includes a distance measuring sensor (measuring device) 51, a rotary encoder 52, a judgment device 53A, a storage device 54, and a display device 55. The distance measuring sensor 51, rotary encoder 52, storage device 54, and display device 55 are the same as in the first embodiment.

[0098] The distance measuring sensor 51 is configured to face the linerboard A at a predetermined distance away from the linerboard A, which is the other side of the corrugated cardboard S being transported, in the thickness direction of the cardboard S. The distance measuring sensor 51 measures at least the distance to the top edge of the downstream side of the corrugated cardboard S and the distance to the recesses formed on the grid lines 101, 102 of the corrugated cardboard S. The function of the distance measuring sensor 51 is the same as in the first embodiment, but its placement is different.

[0099] The judging device 53A compares the distance from the recess of the grid lines 101, 102 at a predetermined judging area in the conveying direction Y of the corrugated cardboard S to a predetermined threshold, thereby judging the corrugated cardboard S as defective.

[0100] When the corrugated cardboard S is conveyed along the conveying direction Y with an appropriate orientation, the top end Sa is located on the downstream side, the rear end Sb is located on the upstream side, the backing plate B is located on the lower surface side, and the front end A is located on the upper surface side. The distance measuring sensor 51 measures the distance H (measurement distance) of the top end Sa, the distance H+H2 (measurement distance) of the second grid line 101b in the determination area A1, the distance H+H2 (measurement distance) of the second grid line 102b in the determination area A2, and the distance H (measurement distance) of the rear end Sb. The distance measuring sensor 51 then outputs the measured distances obtained through measurement to the determination device 53A. The determination device 53A receives the measured distances from the distance measuring sensor 51 and the conveying position of the corrugated cardboard S from the rotary encoder 52. That is, the determination device 53A obtains the measured distances at the positions corresponding to the determination area A1, i.e., the distance H+H2 of the second grid line 101b, and the measured distances at the positions corresponding to the determination area A2, i.e., the distance H+H2 of the second grid line 102b.

[0101] In this case, the determination regions A1 and A2 are the same as in the first embodiment, and are the lengths of the regions obtained by comprehensively considering a predetermined allowance value on the upstream and downstream sides of the conveying direction Y for lengths La and Lb. However, the determination regions A1 and A2 can also be set as the lengths of the regions obtained by comprehensively considering a predetermined allowance value on the upstream and downstream sides of the conveying direction Y for the length from the top Sa of the corrugated cardboard S to the second grid lines 101b and 102b.

[0102] If the measured distance (here, distance H+H2) at the determination areas A1 and A2 input from the distance measurement sensor 51 is greater than the first threshold HA, the determination device 53A determines that the corrugated cardboard S has a front and back defect. Furthermore, if the measured distance is less than the second threshold HB, the determination device 53A determines that the corrugated cardboard S has a front and back defect.

[0103] Figure 12 This is a flowchart illustrating the judgment and control methods for defect detection of corrugated cardboard.

[0104] like Figure 11 and Figure 12 As shown, in step S21, the determining device 53A determines whether the top of the corrugated cardboard S is detected based on information input from the distance measuring sensor 51. If the determining device 53A determines that the top of the corrugated cardboard S is not detected (No), the process of step S21 continues. On the other hand, if the determining device 53A determines that the top of the corrugated cardboard S is detected (Yes), the process proceeds to step S22.

[0105] In step S22, the determining device 53A acquires the measured distance of the corrugated cardboard S at the determining areas A1 and A2 as measured by the distance measuring sensor 51. In step S23, the determining device 53A determines whether the measured distance is greater than the first threshold HA. If the determining device 53A determines that the measured distance is greater than the first threshold HA (yes), then in step S24, the corrugated cardboard S is determined to be defective, with a poor surface and back.

[0106] On the other hand, if the determining device 53A determines that the measured distance is not greater than the first threshold HA (No), it proceeds to step S25. In step S25, the determining device 53A determines whether the measured distance is greater than the second threshold HB. If the determining device 53A determines that the measured distance is greater than the second threshold HB (Yes), it determines in step S26 that the corrugated cardboard S is a qualified product.

[0107] On the other hand, if the determination device 53A determines that the measured distance is not greater than the second threshold HB (no), then in step S27, it determines that the corrugated cardboard S is a defective product, which is defective both before and after.

[0108] [Effects of this implementation method]

[0109] The first embodiment of the corrugated cardboard defect detection device includes: a distance measuring sensor (measuring device) 51, which is configured to face one or the other side of the corrugated cardboard S, and measures and acquires the distance from the configuration position to the top of the corrugated cardboard S and the distance to the recess of the first grid line 101a, 102a or the second grid line 101b, 102b as the measuring distance; a storage device 54, which stores preset thresholds HA, HB; and a judgment device 53, which compares the measuring distance with the thresholds HA, HB in preset predetermined judgment areas A1, A2 from the top of the corrugated cardboard S toward the rear end, thereby determining the relationship between the measuring distance and the thresholds HA, HB, and judging whether the corrugated cardboard S has surface defects or front and back defects.

[0110] According to the first embodiment of the corrugated cardboard defect detection device, since the depth H1 of the recesses formed on one side of the corrugated cardboard S through the first grid lines 101a and 102a is different from the depth H2 of the recesses formed on the other side through the second grid lines 101b and 102b, defects on the front and back sides or front and back sides can be determined by comparing the measured distance with thresholds HA and HB. As a result, defects in the conveying state of the corrugated cardboard S can be appropriately detected.

[0111] When corrugated boxes G are manufactured, the box-making machine 30 discharges them in bundles after dividing them into a predetermined number of batches. Then, the operator picks out defective corrugated boxes G from the discharged bundles. At this time, if the defect detection device 50 can detect surface defects and front / back defects of the corrugated cardboard S as different defects, the operator's task of picking out defective corrugated boxes G (corrugated cardboard S) from the bundles of corrugated boxes G becomes easier. That is, for a bundle of corrugated boxes G, regarding front / back defects, since the positions of the grid lines 101 and 102 in the conveying direction Y are different from those of qualified products, the operator can easily detect corrugated boxes G with front / back defects. On the other hand, for a bundle of corrugated boxes G, regarding surface defects, since the positions of the grid lines 101 and 102 in the conveying direction Y are the same as those of qualified products, the operator finds it difficult to detect corrugated boxes G with surface / back defects. However, when dealing with bundles of corrugated boxes G, if defects at the front and back, as well as defects on the surface and back, are known to be mixed together, the operator can easily identify the corrugated boxes G with defects at the front and back, as well as those with defects on the surface and back. As a result, it becomes easier for the operator to pick out the defective corrugated boxes G from the bundles of corrugated boxes G, which can shorten the operation time and reduce the number of defective corrugated boxes G that are missed.

[0112] The defect detection device for corrugated cardboard according to the second aspect is the defect detection device for corrugated cardboard according to the first aspect, further comprising: a first threshold HA and a second threshold HB smaller than the first threshold HA, wherein the determining device 53 compares the measured distance with the first threshold HA and the second threshold HB, thereby determining the magnitude relationship between the measured distance and the first threshold HA and the second threshold HB, and determines front-back reversed defect and head-tail reversed defect of the corrugated cardboard S. Thereby, the front-back reversed defect and the head-tail reversed defect can be respectively determined by comparing the measured distance with the different thresholds HA and HB.

[0113] The defect detection device for corrugated cardboard according to the third aspect is the defect detection device for corrugated cardboard according to the second aspect, further comprising: the distance measuring sensor 51 is arranged to face one surface of the corrugated cardboard S, and when the measured distance is smaller than the first threshold HA and larger than the second threshold HB, the determining device 53 determines that the corrugated cardboard S has a front-back reversed defect. Thereby, when the distance measuring sensor 51 is arranged on the side of the surface of the corrugated cardboard S where the first score lines 101a and 102a are formed, the determining device 53 can easily determine whether the corrugated cardboard S is a qualified product or has a front-back reversed defect by comparing the measured distance with the first threshold HA and the second threshold HB.

[0114] The defect detection device for corrugated cardboard according to the fourth aspect is the defect detection device for corrugated cardboard according to the third aspect, further comprising: when the measured distance is smaller than the second threshold HB, the determining device 53 determines that the corrugated cardboard S has a head-tail reversed defect. Thereby, the head-tail reversed defect of the corrugated cardboard S can be easily determined.

[0115] The defect detection device for corrugated cardboard according to the fifth aspect is the defect detection device for corrugated cardboard according to the second aspect, further comprising: the distance measuring sensor 51 is arranged to face the other surface of the corrugated cardboard S, and when the measured distance is larger than the first threshold HA, it is determined that the corrugated cardboard S has a front-back reversed defect. Thereby, when the distance measuring sensor 51 is arranged on the side of the other surface of the corrugated cardboard S where the second score lines 101b and 102b are formed, the determining device 53 can easily determine whether the corrugated cardboard S is a qualified product or has a front-back reversed defect by comparing the measured distance with the first threshold HA.

[0116] The defect detection device for corrugated cardboard according to the sixth aspect is the defect detection device for corrugated cardboard according to the fifth aspect, further comprising: when the measured distance is smaller than the second threshold HB, the determining device 53 determines that the corrugated cardboard S has a head-tail reversed defect. Thereby, whether the corrugated cardboard S is a qualified product or has a head-tail reversed defect can be easily determined.

[0117] The seventh embodiment of the corrugated cardboard defect detection device is a defect detection device for corrugated cardboard from any of the first to sixth embodiments. Further, the measuring device is a common distance measuring sensor 51 that measures the distance from the configuration position to the top of the corrugated cardboard S and the distance to the recesses of the first grid lines 101a, 102a or the recesses of the second grid lines 101b, 102b. This simplifies the device and reduces its cost.

[0118] The eighth embodiment of the corrugated cardboard defect detection method includes the following steps: measuring and acquiring the distance from a predetermined position opposite one or the other side of the corrugated cardboard S to the top of the corrugated cardboard S and the distance to the recess of the first grid lines 101a, 102a or the second grid lines 101b, 102b as measurement distances; comparing the measurement distances with predetermined thresholds HA, HB in predetermined judgment areas A1, A2 from the top of the corrugated cardboard S toward the rear end; and determining the relationship between the measurement distances and the thresholds HA, HB to determine whether the corrugated cardboard S has surface defects or front / back defects. Thus, surface defects or front / back defects can be determined by comparing the measurement distances with the thresholds HA, HB. As a result, defects in the conveying state of the corrugated cardboard S can be appropriately detected.

[0119] The ninth embodiment of the corrugated board defect detection method is a further improvement upon the eighth embodiment, comprising the following steps: comparing the measured distance with a first threshold HA in judgment areas A1 and A2; comparing the measured distance with a second threshold HB, which is smaller than the first threshold HA, in judgment areas A1 and A2; and determining the relationship between the measured distance and the first and second thresholds HA and HB to determine the front / back and front / back defects of the corrugated board S. Thus, by comparing the measured distance with different thresholds HA and HB, front / back and front / back defects can be determined separately. As a result, defects in the conveying state of the corrugated board S can be appropriately detected.

[0120] The tenth embodiment of the carton-making machine includes a defect detection device 50. This allows for the determination of whether there are defects on the front or back, or front and back, by comparing the measured distance with thresholds HA and HB. As a result, defects in the conveying state of the corrugated cardboard S can be appropriately detected. Furthermore, the operation of picking out defective corrugated cardboard boxes G from the bundles discharged from the carton-making machine 30 becomes easier, reducing operation time and minimizing the omission of defective corrugated cardboard boxes G.

[0121] It should be noted that in the above description of the embodiment, the threshold values ​​HA and HB are set by adding the design value of Ha and Hb, which are obtained by comprehensively considering the depth of the recesses of the groove lines 101a, 101b, 102a, and 102b, to the distance H from the distance measuring sensor 51 to the plane of the corrugated cardboard S. A defect is determined by comparing the measured distance from the distance measuring sensor 51 to the corrugated cardboard S with the threshold values ​​HA and HB, but this method is not limited to this determination method. For example, the threshold values ​​HA and HB can also be set as Ha and Hb, which are obtained by comprehensively considering the depth of the recesses of the groove lines 101a, 101b, 102a, and 102b, and a defect is determined by comparing the value obtained by subtracting the distance H from the measured distance from the distance measuring sensor 51 to the corrugated cardboard S with the threshold values ​​Ha and Hb.

[0122] Furthermore, in the above-described embodiment, the corrugated cardboard S has a grid line 101 formed downstream in the conveying direction Y, and a grid line 102 formed upstream of the grid line 101 in the conveying direction Y. Two determination areas A1 and A2 are provided, and defects are determined by comparing the measured distances measured in each determination area A1 and A2 with a first threshold HA and a second threshold HB, but this configuration is not limited to this. In the corrugated cardboard S, depending on the specifications, there may be one, three, four, or other grid lines. In this case, determination areas corresponding to each grid line may also be provided, and defects may be determined by comparing the measured distances measured in each determination area with the first threshold HA and the second threshold HB. Alternatively, defects may be determined by comparing the measured distances with the first threshold HA and the second threshold HB in at least one of the determination areas.

[0123] Furthermore, in the above description of the embodiments, the box-making machine 30 is configured to include a paper feeding unit 31, a printing unit 32, a paper discharge unit 33, a die-cutting unit 34, a folding and gluing unit 35, and a counting and discharge unit 36, but it is not limited to this configuration. The box-making machine 30 may, for example, include a paper feeding unit 31, a printing unit 32, and a paper discharge unit 33. Furthermore, the box-making machine 30 may, for example, include a paper feeding unit 31, a printing unit 32, a paper discharge unit 33, and a die-cutting unit 34. Furthermore, the box-making machine 30 may, for example, include a paper feeding unit 31, a printing unit 32, and a die-cutting unit 34.

[0124] Explanation of reference numerals in the attached figures

[0125] 10: Corrugated board machine;

[0126] 11, 12, 15, 16, 19: Original paper holders;

[0127] 13, 17: Single-sided machine;

[0128] 14, 18: Bridge;

[0129] 20: Preheater;

[0130] 21: Glue applicator;

[0131] 22: Double-sided machine;

[0132] 23: Rotary shearing machine;

[0133] 24: Slitting and pressing machine;

[0134] 25: Cutting machine;

[0135] 26: Defective product discharge device;

[0136] 27: Palletizer;

[0137] 30: Box making machine;

[0138] 31: Paper supply department;

[0139] 32: Printing Department;

[0140] 33: Paper layout section;

[0141] 34: Punching section;

[0142] 35: Folded adhesive part;

[0143] 36: Counting and discharging section;

[0144] 50, 50A: Defective detection device;

[0145] 51: Distance measurement sensor (measuring device);

[0146] 52: Rotary encoder;

[0147] 53, 53A: Determination device;

[0148] 54: Storage device;

[0149] 55: Display device;

[0150] 101: Grid lines;

[0151] 101a: First grid line;

[0152] 101b: Second grid line;

[0153] 102: Grid lines;

[0154] 102a: First grid line;

[0155] 102b: Second grid line;

[0156] 111: Cut the line;

[0157] 112, 113, 114, 115: Grid lines;

[0158] 121, 122, 123: slots;

[0159] 124: Gap;

[0160] 131, 132, 133: slots;

[0161] 134: Gap;

[0162] A: Surface lining;

[0163] B, B1, B2: Backing panels;

[0164] C, C1, C2: Core paper;

[0165] D1, D2: Single-sided corrugated cardboard;

[0166] E, F: Composite double-sided corrugated cardboard;

[0167] G: Corrugated cardboard box;

[0168] S, S1: Corrugated cardboard.

Claims

1. A defect detection device for corrugated cardboard, comprising a first grid line recess formed on one side in the thickness direction and a second grid line recess with a depth smaller than the first grid line recess formed on the other side in the thickness direction, and the device includes: The measuring device is configured to face one side or the other side, and measures and obtains the distance from the configuration position to the top of the corrugated cardboard and the distance to the recess of the first grid line or the recess of the second grid line as the measuring distance. A storage device that stores a threshold preset based on the distance from the configuration position to the recess of the first grid line or the recess of the second grid line; as well as The determination device compares the measured distance with the threshold in a pre-defined determination area from the top to the rear of the corrugated cardboard, thereby determining the relationship between the measured distance and the threshold, and determining whether the corrugated cardboard has surface defects or front and back defects.

2. The defect detection device for corrugated cardboard according to claim 1, wherein, The threshold has a first threshold and a second threshold smaller than the first threshold. The determination device compares the measured distance with the first threshold and the second threshold to determine the relationship between the measured distance and the first threshold and the second threshold, and determines the front and back defects and front and back defects of the corrugated cardboard.

3. The defect detection device for corrugated cardboard according to claim 2, wherein, The measuring device is configured to face one side of the corrugated cardboard. If the measuring distance is smaller than the first threshold and larger than the second threshold, the determining device determines that the corrugated cardboard has a front-back defect.

4. The defect detection device for corrugated cardboard according to claim 3, wherein, If the measured distance is smaller than the second threshold, the determination device determines that the corrugated cardboard has front and back defects.

5. The defect detection device for corrugated cardboard according to claim 2, wherein, The measuring device is configured to face the other side of the corrugated cardboard. If the measuring distance is greater than the first threshold, the determining device determines that the corrugated cardboard has a front-back defect.

6. The defect detection device for corrugated cardboard according to claim 5, wherein, If the measured distance is smaller than the second threshold, the determination device determines that the corrugated cardboard has front and back defects.

7. The defect detection device for corrugated cardboard according to any one of claims 1 to 6, wherein, The measuring device is a common distance measuring sensor that measures the distance from the configured position to the top of the corrugated cardboard and the distance to the recess of the first grid line or the recess of the second grid line.

8. A method for detecting defects in corrugated cardboard, comprising the following steps: A method for detecting defects in corrugated cardboard having a recessed portion of a first grid line formed on one side in the thickness direction and a recessed portion of a second grid line formed on the other side in the thickness direction with a depth smaller than that of the recessed portion of the first grid line. The distance from a predetermined position opposite to one side or the other side up to the top of the corrugated cardboard and the distance to the recess of the first grid line or the recess of the second grid line are measured and obtained as the measurement distance. In a predetermined determination area extending from the top of the corrugated cardboard towards the rear, the measured distance is compared with a predetermined threshold value based on the distance from the predetermined position to the recess of the first grid line or the recess of the second grid line; and Determine the relationship between the measurement distance and the threshold to determine whether the corrugated cardboard has defects on the front or back, or defects on the front or back.

9. The defect detection method for corrugated cardboard according to claim 8, comprising the following steps: In the determination area, the measured distance is compared with a first threshold; In the determination region, the measured distance is compared with a second threshold that is smaller than the first threshold; and Determine the relationship between the measured distance and the first and second thresholds to identify defects on the front and back of the corrugated cardboard and defects on the front and back.

10. A box-making machine, comprising: The defect detection device for corrugated cardboard as described in claim 1.

Images