JP2018013384A - Inspection method and device of heat seal part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the positional deviation with respect to a pattern of a heat seal part.SOLUTION: An inspection device images an inspection object heat seal part by an infrared camera 50 in a stop state of a bag-making film 1, images an inspection object pattern portion by a visible light camera 60, calculates the physical relation between the heat seal part and the pattern on the basis of a value equivalent to an inter-arrangement distance between the infrared camera and the visible light camera, a specific position of the heat seal portion in a thermal image captured by the infrared camera, and a specific position in a pattern image captured by the visible light camera, and determines whether or not the positional deviation amount with respect to the pattern of the heat seal portion is within an allowable range on the basis of the measurement result.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method and apparatus for inspecting a heat seal portion, and in particular, printing on a bag making film (heat seal portion) welded or bonded to a bag making film (generally a plastic film) and a bag making film. It is related with the method and apparatus which test | inspect the position shift between the patterns (including a reference mark) represented by (3), and the feature-value (a position, a shape, a width | variety, length, etc.) of a heat seal part.

  This kind of heat seal portion inspection method and apparatus are described in the following Patent Documents 1 and 2.

JP 2001-116517 A JP 2012-197084 A

  In any of the inspection methods and apparatuses described in Patent Documents 1 and 2, paying attention to the difference in reflectance between the heat seal part and the part other than the heat seal part, the amount of reflected light of the projected light Is detected. In particular, since the heat seal portion has small unevenness formed when heat sealing, an illumination method and an imaging method are used to emphasize the small unevenness.

  However, it is not always easy to accurately distinguish between shadows caused by the unevenness of the heat seal part and shades of patterns. In particular, when the film to be heat-sealed is mat-type solid printing, it is difficult to optically distinguish between small unevenness due to matte and small unevenness in the heat-sealed part. In some cases, the device could not be used depending on the type of pattern and printing mode.

  This invention measures or determines the positional deviation of the heat seal part with respect to the picture (especially the reference mark) or the relative relationship between the heat seal part and the picture in the bag making process, regardless of the pattern of the film for bag making. It is an object of the present invention to provide an inspection method and apparatus capable of performing the above.

  The present invention also provides an inspection method and apparatus capable of measuring the feature quantity (position, shape, width, length, etc. of the heat seal portion) of the heat seal portion regardless of the form of the surface of the plastic film.

  The inspection apparatus for a heat seal portion according to the present invention includes an infrared camera disposed at a position for photographing a heat seal portion to be inspected and a visible position disposed at a position for photographing a pattern portion to be inspected when the bag-making film is stopped. An optical camera, a value corresponding to a distance between the arrangement of the infrared camera and the visible light camera (a value corresponding to a distance on the image), a specific position of a heat seal portion in a thermal image taken by the infrared camera, and the Measuring means for measuring the positional relationship between the heat seal part and the picture based on a specific position in the picture image taken by the visible light camera is provided.

  An inspection apparatus for a heat seal portion according to the present invention is configured to take an image of a heat seal portion to be inspected with an infrared camera and a picture portion to be inspected with a visible light camera when the film for bag making is stopped. Based on the value corresponding to the distance between the arrangement with the visible light camera, the specific position of the heat seal portion in the thermal image captured by the infrared camera, and the specific position in the pattern image captured by the visible light camera The positional relationship between the pattern and the pattern is measured.

  In the heat seal portion of the bag-making film heated by the processing unit for heat sealing, the heat of heating still remains immediately after the heat sealing (before cooling by the cooling unit). If this thermal image is taken with an infrared camera, a thermal image representing the shape of the heat seal can be obtained. On the other hand, a part of the pattern of the bag-making film, particularly the reference mark, is photographed by a visible light camera. In this way, the heat-sealed portion and the image of the pattern are obtained through separate media (infrared rays and visible light) while the bag-making film that is intermittently conveyed is stopped. If the distance between the arrangement of the infrared camera and visible light camera is known in advance, this distance, in particular the value on the image corresponding to the distance in the carrying direction of the bag-making film, the specific position and the picture of the image of the heat seal part Based on the specific position of the image, the positional relationship with respect to the pattern of the heat seal portion can be measured. It is also possible to determine whether the amount of positional deviation between the specific position of the heat seal portion and the specific position of the pattern is within an allowable range.

  According to the present invention, the heat seal part is photographed using infrared rays, paying attention to the fact that the heat seal part has heat immediately after the heat seal, and the picture medium is different from the picture of the film. It is possible to measure or determine the positional relationship of the heat seal part with respect to the picture without depending on the above.

  The present invention also provides an inspection apparatus and method capable of measuring the feature quantity of the heat seal portion of the film for bag making without being influenced by other forms on the surface of the film.

  An inspection apparatus for a heat seal portion according to the present invention is a bag making machine that intermittently conveys a long length of a film for bag making by a predetermined length and heat-seals a predetermined portion by a processing unit in a stopped state. An infrared camera disposed at a position where the heat seal portion is photographed, and a measurement unit that measures a feature amount of a thermal image obtained by the infrared camera are provided.

  The inspection method of the heat seal portion according to the present invention is a bag making machine that intermittently conveys a long length of a film for bag making by a predetermined length and heat-seals a predetermined portion by a processing unit in the stop state. The target heat seal portion is photographed by a camera, and the feature amount of a thermal image obtained by the infrared camera is measured.

  Immediately after the bag-making film is heated by the heat seal unit (before it is cooled), heat remains in the heat-sealed part of the film. An image is obtained. Since the image of the heat-sealed part is obtained using a medium different from visible light called infrared, the shape of the heat-sealed part is not affected by the form of the surface of the bag-making film, for example, small unevenness due to matte solid printing , Features such as position, width and length can be measured. These feature amounts can be used for determination of misalignment of the heat seal portion.

The arrangement | positioning of each process unit arrange | positioned on the film conveyance path of a bag making machine is shown. The heat seal part formed in the film for bag making is shown. The produced bag is shown. It is a block diagram which shows the electric constitution of a test | inspection apparatus. A part of film containing a bottom seal part field is expanded and shown. The arrangement | positioning relationship of an infrared camera and visible light camera, and a film is shown. The example of the thermal image by an infrared camera is shown. The example of the color image by a visible light camera is shown. The image obtained by superimposing the images of FIG. 7 and FIG. 8 is shown. FIG. 10 shows an image obtained by shifting the color image by a length corresponding to the distance L1 in the superimposed image of FIG. A part of film containing a side seal part field is expanded and shown. The arrangement | positioning relationship of an infrared camera and visible light camera, and a film is shown. The example of the thermal image by a visible light camera is shown. The example of the color image by an infrared camera is shown. 15 shows an image obtained by superimposing the images of FIG. 13 and FIG. 15 shows an image obtained by shifting the thermal image by a length corresponding to the distance L2 in the superimposed image of FIG.

  FIG. 1 shows a processing unit arranged on the conveyance path of a bag-making film (or sheet) that is intermittently conveyed by a bag-making machine, and FIG. 2 shows a heat seal formed on the bag-making film by the processing unit. Shows the part.

  The bag making machine includes a conveyance device, and the conveyance device intermittently conveys the long bag making film 1 by a fixed pitch with a nip roll or the like (not shown). The nip roll or the like is driven by a motor, and an accurate intermittent conveyance drive is performed by feeding back an encoder output attached to the rotation axis of the nip roll or the rotation axis of the conveyance motor to the drive circuit of the conveyance motor.

  Two sheets of the bag-making film 1 are stacked, and in this embodiment, the film is conveyed from right to left in FIGS. 1 and 2 in a horizontal plane. Generally, the film 1 is a plastic film, and a pattern (including characters and the like) (not shown) is repeatedly printed at a constant pitch (print pitch). There is a reference mark 5 in a part of this pattern. The reference marks 5 are also expressed at a constant pitch, and in this embodiment, they are used as a reference for determining the amount of deviation of the heat seal portion.

  An example of a bag produced by a bag making machine is shown in FIG. A portion corresponding to the bottom of the two stacked films (bottom seal portion 3A) and a portion corresponding to both sides (side seal portion 4A) (both are represented by gray (dots)) are thermocompression-bonded ( A square bag 2 is formed by heat welding. The remaining side of the square bag 2 is open.

  In particular, as shown in FIG. 2, on the two-layer film 1 that is intermittently conveyed, as shown by a chain line 2A, bags are formed in two rows in a direction (width direction) orthogonal to the conveying direction. There is a gap (a margin of punching allowance that does not become a bag) (margin) between the bags formed adjacent to each other in the conveyance direction and the width direction. There is also a portion that becomes a punching margin (margin) between the formed bag and the side edge of the film 1.

  In particular, as shown in FIG. 1, along the conveyance direction of the bag making machine, the bottom seal unit 30, the bottom seal cooling unit 35, the side seal unit 40, the side seal cooling unit 45, and the upstream from the upstream in the conveyance direction. A punching unit (not shown) is arranged. Processing (heating, cooling, punching) by these units is performed when the intermittently fed film 1 is stopped.

  It has upper and lower molds that simultaneously form the bottom seal portion of a continuous bag for 303 bottom seal units. This mold is heated, and the film 1 is sandwiched from above and below and thermocompression bonded (thermal welding). If attention is paid to one bag, it will be subjected to sealing processing three times for each intermittent feed. Accordingly, the portion of the punching allowance continuous to the bottom of the adjacent bag is also sealed. The next-stage bottom seal cooling unit 35 also has a mold having the same shape as the bottom seal unit 30. The mold is cooled, and the film 1 heated by the bottom seal unit 30 is cooled. The bottom seal unit 30 and the cooling unit 35 are arranged at positions corresponding to both side edges of the film 1 to be conveyed.

  Two side seal units 40 are provided with one pitch separated in the conveying direction, and each has a long rectangular upper and lower molds that cover the entire width of the film 1. These molds are also heated, and the adjacent side portions of two bags adjacent in the transport direction are simultaneously heat-sealed. Accordingly, the punching allowance (margin) between the side seal portions of the adjacent bags is also heat sealed. The side seal cooling unit 45 also has a pair of upper and lower molds of the same type as the side seal unit 40. The molds are cooled and heated by the side seal unit 40 (side seal portion and margin). Cool down.

  The punching unit cuts (cuts) the film 1 along the lines corresponding to the four sides of the bag indicated by the chain line 2A, and separates the bag 2 from the film 1.

  Parts heated by the bottom seal unit 30 and the side seal unit 40 that are higher than normal temperature (heated parts) are indicated by hatching in FIGS. The portions heated by these sealing units have heat until they are cooled by the cooling units 35 and 45 in the next stage, so the film portion between the bottom sealing unit 30 and the cooling unit 35 is heated. Part of the film portion between the side seal unit 40 and its cooling unit 45 is also hatched.

  As described later, between the bottom seal unit 30 and its cooling unit 35 and between the side seal unit 40 and its cooling unit 45, above (or below) the side of the conveyance path of the film 1. Are provided with infrared cameras (thermographic cameras, thermal image cameras) 50 and 51 and visible light (color) cameras 60 and 61 for photographing the film portion immediately below.

  The bag-making film 1 is mainly a plastic film, and may slip and stretch in the process of conveyance. If it does so, the pattern and bottom seal part and side seal part which are represented by the fixed pitch on the film 1 may shift. When this deviation becomes large, a part of the bag 2 after punching may not be sealed (unsealed), and as a result, it cannot be used as a bag.

  The inspection device measures the displacement of the positions of the bottom seal portion 3A and the side seal portion 4A with reference to the pattern (especially the reference mark 5) shown on the film 1, and determines whether the displacement is within an allowable range. Judgment. The electrical configuration of this inspection apparatus is shown in FIG.

  The inspection device 10 includes a processing device 11, a setting unit 12, and a determination result output unit 13, and the above-described infrared cameras 50 and 51 and visible light cameras 60 and 61 are connected to the processing device 11. The processing device 11 is realized by a computer, for example, and includes a storage unit (not shown). The processing device 11 executes image processing and measurement determination processing described later (measurement means, determination means). The setting unit 12 is an input device, and includes not only a keyboard and a mouse but also a communication device that receives transmitted data and a storage device that stores the data. The setting unit 12 sets a threshold value indicating an allowable range described later. The determination result output unit 13 outputs measurement results by the processing device 11 and pass / fail determination results, and is realized by a display device, an output device, a communication device, a storage device, or the like. The output unit 13 stores a defective portion of the film and outputs a discharge signal for discharging from the conveyance path after the punching is completed. FIG. 1 shows two infrared cameras 50 and 51 and visible light cameras 60 and 61 arranged on the left and right of the conveyance path, but the processing based on the left and right sets of cameras is the same. For convenience of explanation, infrared cameras 50 and 51 and visible light cameras 60 and 61 arranged on one side are shown in FIG. 4 as representatives.

  5 to 10 show processing for measuring and determining the displacement of the bottom seal portion 3A.

  FIG. 5 shows the state of the film 1 in a range that is traced back by three pitches of the pattern from the position of the end of the bottom seal cooling unit 35 on the upstream side in the conveying direction to the upstream side. Although the bottom seal portion of the manufactured bag 2 is indicated by reference numeral 3A (FIG. 3), the bottom seal portion shown in FIG. 5 and the sealed area around the bottom seal portion are adjacent to the corresponding bag portion for each pitch. This includes the punching allowance (margin) between the sides of the film 1 and the punching allowance (margin) between the sides of the film 1 and is referred to as a bottom seal portion region, and is indicated by reference numeral 3 (indicated by hatching or dotted gray display).

  FIG. 6 shows the relationship between the infrared camera 50 and the visible light camera 60 and the range including the bottom seal area 3 and the reference mark 5 on the film 1 imaged by these cameras. The infrared camera 50 and the visible light camera 60 are arranged so that their optical axes are orthogonal to the surface of the film 1, and photograph the surface of the film 1 from vertically above. The field of view of the infrared camera 50 is set in a range in which the reference mark 5 can be accommodated so that the portion representing the feature amount of the bottom seal area 3 can be contained in the thermal image. Is done. The field of view of these cameras is preferably about one pitch of the pattern in the transport direction of the film 1. The distance between the two cameras 50 and 60 (the distance between the optical axes), in this embodiment, the distance L1 along the transport direction of the film 1 is preset or measured.

  FIG. 7 shows a thermal image taken by the infrared camera 50. A thermal image (indicated by reference numeral 3a) of the adjacent bottom seal portion region 3 is shown. FIG. 8 shows a color image taken by the visible light camera 60. An image 5a of the reference mark 5 appears. Shooting by these two cameras 50 and 60 is performed simultaneously and when the film 1 is in a stopped state.

  FIG. 9 is a superposition of the thermal image of FIG. 7 and the color image of FIG. 8 (the optical magnifications of the two cameras 50 and 60 are the same). FIG. 10 shows that the color image is moved (shifted) in the superimposed image by the length on the image corresponding to the distance L1 between the optical axes of the two cameras 50 and 60 (in the direction corresponding to the transport direction). The obtained image is shown. FIG. 10 accurately represents the bottom seal portion region 3 and the reference mark 5 that actually appear on the film 1. The above image processing is performed by the processing device 11.

  The processing device 11 further performs the following measurement process and determination process. The feature amount of the thermal image 3a in the bottom seal portion region is obtained on the image of FIG. The bottom seal part has a curved edge that curves in the range of each bag in accordance with the shape of the mold of the bottom seal unit 30, and there is a raised convex seal part between adjacent bottom seal parts . Intersection points 31 and 32 between the curved line and the convex portion are cited as feature points. The conveyance direction of the film 1 is taken as the X axis and the width direction is taken as the Y axis. The midpoint 33 between the two feature points 31 and 32 is set as a feature point of the bottom seal portion region. The X and Y coordinates of the midpoint 33 are feature quantities.

  With respect to the reference mark image 5a, the X and Y coordinates of the center point (center of gravity) of the reference mark image 5a are used as feature amounts.

  Using these feature amounts, distances X1 and Y1 in the X and Y axis directions between the point 33 on the thermal image and the center of the reference mark image 5a are obtained. These distances are compared with parameters (threshold values) Xa, Xb, Ya, Yb that define a predetermined allowable range.

  If the distance X1 satisfies Xa ≦ X1 ≦ Xb, the deviation between the bottom seal portion and the reference mark is good (OK) in the X-axis direction, and if X1 <Xa or X1> Xb, it is determined as defective (NG).

  Also in the Y direction, if Ya ≦ Y1 ≦ Yb is satisfied, the deviation between the bottom seal portion and the reference mark is good (OK) in the Y axis direction, and if Y1 <Ya or Y1> Yb, it is determined as bad (NG). To do.

  These parameters Xa, Xb, Ya, Yb are input from the setting unit 12.

  FIGS. 11 to 16 show processing for measuring and determining the deviation of the side seal portion 4A.

  FIG. 11 shows the state of the film 1 in a range that is traced back by 3 pitches from the position 1 pitch upstream of the pattern in the transport direction from the side seal cooling unit 45. The side seal portion of the manufactured bag 2 is indicated by reference numeral 4A (FIG. 3), but the range indicated by hatching in FIG. 11 includes side seals of adjacent bag portions and a margin between them. Is referred to as a side seal portion region and is denoted by reference numeral 4.

  FIG. 12 shows the relationship between the visible light camera 61 and the infrared camera 51 and the range including the side seal portion area 4 and the reference mark 5 on the film 1 imaged by these cameras. The visible light camera 61 and the infrared camera 51 are arranged so that their optical axes are orthogonal to the surface of the film 1 and photograph the surface of the film 1 from vertically above. The visual field of the visible light camera 51 is set in a range in which the reference mark 5 can be accommodated, and the visual field of the infrared camera 51 can accommodate a portion representing the feature amount of the side seal portion region 4 in the thermal image. Set to The range of these visual fields is preferably about one pitch of the pattern in the transport direction of the film 1. The distance between the two cameras 61 and 51 (the distance between the optical axes), in this embodiment, the distance L2 along the transport direction of the film 1 is preset or measured.

  FIG. 13 shows a color image taken by the visible light camera 61. An image 5a of the reference mark 5 appears. FIG. 14 shows a thermal image taken by the infrared camera 51. A thermal image (indicated by reference numeral 4a) of the side seal portion region 4 appears. Shooting by these two cameras 61 and 51 is performed simultaneously and when the film 1 is in a stopped state.

  FIG. 15 is an overlay of the color image of FIG. 13 and the thermal image of FIG. 14 (the optical magnifications of the two cameras 61 and 51 are the same). In FIG. 16, the thermal image is moved (shifted) in the superimposed image by the length on the image corresponding to the distance L2 between the optical axes of the two cameras 61 and 51 (in the direction corresponding to the transport direction). The obtained image is shown. FIG. 16 accurately represents the side seal portion region 4 and the reference mark 5 that actually appear on the film 1. The above image processing is performed by the processing device 11.

  The processing device 11 further performs the following measurement process and determination process. The feature amount of the thermal image 4a in the side seal portion area is obtained on the image of FIG. The side seal portion region has a thick band shape extending in the Y-axis direction. The X coordinate of the center (feature point) of the X coordinates of both sides 41 and 42 of this strip-shaped thermal image is used as the feature amount of the side seal portion region 4a.

  For the reference mark image 5a, the X coordinate of the center point (centroid point) of the reference mark image 5a is used as a feature amount.

  Using these feature amounts, a distance X2 in the X-axis direction between the feature point on the thermal image and the center of the reference mark image 5a is obtained. This distance X2 is compared with parameters (threshold values) Xc and Xd (input from the setting unit 12) for obtaining a predetermined allowable range.

  If the distance X2 satisfies Xc ≦ X1 ≦ Xd, the deviation between the side seal portion and the reference mark is good (OK) in the X-axis direction, and if X1 <Xc or X1> Xd, it is determined as defective (NG).

  Regarding the Y direction of the side seal portion region 4a, if the mold of the side seal unit 40 is sufficiently longer than the width of the film 1, it is not necessary to measure the deviation.

  In the above description, for ease of understanding, the color image is shifted by a length corresponding to the distance L1 in FIG. 9 to derive FIG. 10, and the thermal image is shifted by a length corresponding to the distance L2 in FIG. However, since the image shift of these lengths L1 and L2 can be executed in the calculation for deriving X1 and X2, image shift processing is not necessarily required. In addition, it is possible to more accurately determine the amount of deviation by correcting lens distortion as necessary.

  When it is determined that the bottom seal area or the side seal area is defective (NG), the position of the area determined as NG on the film is stored, and the number of conveyance pitches by intermittent conveyance is stored. Can be removed when the bag including the region at that position reaches the defective discharge portion (after the punching unit).

DESCRIPTION OF SYMBOLS 1 Film for bag making 2 Bag 2A Bag part 3 Bottom seal part area | region 3A Bottom seal part 3a Thermal image 4 Side seal part area | region 4A Side seal part 4a Thermal image 5 Reference mark 5a Color image of a reference mark
10 Inspection equipment
11 Processing device (image processing means, measurement means, judgment means)
12 Setting section
13 Judgment result output section
30 Bottom seal unit
31, 32, 33 Features
35 Bottom seal cooling unit
40 Side seal unit
41, 42 Side edges of the zonal image
45 Side seal cooling unit
50, 51 infrared camera
60, 61 Visible light camera

Claims (6)

An infrared camera disposed at a position for photographing the heat seal portion to be inspected, a visible light camera disposed at a position for photographing the pattern portion to be inspected, and the infrared camera and the visible light when the film for bag making is stopped Based on the value corresponding to the distance between the camera and the arrangement, the specific position of the heat seal part in the thermal image taken by the infrared camera, and the specific position in the picture image taken by the visible light camera Measuring means for measuring the positional relationship with
A seat heel inspection apparatus comprising: The measurement means includes a determination means for determining whether or not a positional deviation amount between the specific position of the heat seal portion and the specific position of the pattern is within an allowable range;
The heat sealing unit inspection apparatus according to claim 1. In a bag making machine that transports a long bag making film intermittently by a predetermined length and heat seals a predetermined part by a processing unit in a stopped state,
An infrared camera disposed at a position where the target heat seal portion is photographed in a stopped state, and a measuring means for measuring a feature quantity of a thermal image obtained by the infrared camera;
An inspection apparatus for a heat seal part comprising: While the bag-making film is stopped, the heat seal part to be inspected is photographed with an infrared camera, and the pattern part to be inspected is photographed with a visible light camera.
Based on a value corresponding to a distance between the arrangement of the infrared camera and the visible light camera, a specific position of a heat seal portion in a thermal image photographed by the infrared camera, and a specific position in a picture image photographed by the visible light camera Measuring the positional relationship between the heat seal part and the pattern,
Inspection method of heat seal part. Based on the above measurement, determine whether the amount of positional deviation between the specific position of the heat seal part and the specific position of the pattern is within the allowable range.
The inspection method of the heat seal part of Claim 4. In a bag making machine that transports a long bag making film intermittently by a predetermined length and heat seals a predetermined part by a processing unit in a stopped state,
Shoot the target heat seal part with the infrared camera in the stop state,
Measure the feature value of the thermal image obtained by the infrared camera,
Inspection method of heat seal part.

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