JP6186728B2 - Preform inspection method and preform inspection apparatus - Google Patents

Description

  The present invention relates to a preform inspection method and a preform inspection apparatus molded into a bottle-shaped synthetic resin container by blow molding, and in particular, an undissolved gel that is a visible defect generated in the preform, a brown discoloration portion, The present invention relates to a preform inspection method and a preform inspection apparatus capable of selectively detecting a black color changing portion and a solid foreign matter.

  Conventionally, a synthetic resin bottle formed by forming a bottomed cylindrical preform using a thermoplastic resin such as polyethylene terephthalate, and then molding the preform into a bottle shape by biaxial stretch blow molding or the like, It is generally used in a wide field as a beverage container in which beverages are filled as contents. When mass-producing such synthetic resin bottles, it is desired to increase the productivity by inspecting the preforms for defects prior to blow molding and eliminating preforms having defects. .

  As a technique for inspecting the presence or absence of defects in a preform, for example, Patent Document 1 discloses a technique of a preform inspection apparatus in which illumination and a CCD camera are arranged so as to sandwich a preform.

  Patent Document 2 discloses a technique of an inspection apparatus that inspects a transparent inspection object having at least two layers. The apparatus includes a surface light source that emits light having a first wavelength λ1 and light having a second wavelength λ2 different from the first wavelength λ1, and the first wavelength λ1 and the light. An imaging device that images an inspection object irradiated with light of the second wavelength λ2, and image data captured by the imaging device for each of the light of the first wavelength λ1 and the second wavelength λ2. A density value of each pixel is extracted, and a computing device for obtaining a pixel density ratio for the light of the first wavelength λ1 and the light of the second wavelength λ2 for each pixel, the computing device comprising the pixel density Whether the inspection object is good or bad is determined based on the amount of change in the ratio.

  Patent Document 3 also exposes a plastic-colored article to radiation in the near infrared range, measures the radiation returning from or passing through the article, and analyzing the radiation that has returned or passed through. Thus, a technique for providing defect data for the article or its contents is disclosed.

Japanese Patent Laid-Open No. 11-100119 JP 2011-169735 A JP-T-2004-509352

By the way, the applicant's examination from the past has identified some visible defects that may interfere with the molding of the synthetic resin bottle, and the defects are undissolved gel, brown discoloration, black It is called a discoloration part or solid foreign matter.
Here, the undissolved gel refers to a gel-like portion in which the resin of the preform 10 is not dissolved, and is generated in a state where it is depressed on the outer surface or the inner surface of the preform 10 and is white. The undissolved gel is a defect that may become a starting point of breakage when blow-molded, and is not preferable in appearance.
Further, the brown discolored portion refers to a portion where the resin of the preform 10 has changed to brown, and the black discolored portion refers to a portion where the resin of the preform 10 has changed to black, and these are mainly inside the preform 10. Further, the solid foreign matter is a solid foreign matter mixed in the preform 10, and any of them is an undesirable defect in appearance.

(Conventional example)
In order to detect these defects, a conventional example studied by the inventors prior to the completion of the present invention will be described with reference to the drawings.
2A and 2B are schematic diagrams for explaining the preform inspection apparatus in the conventional example. FIG. 2A is a plan view, FIG. 2B is a cross-sectional view taken along the line C-C, and FIG. -D shows a cross-sectional view.

In FIG. 2, a preform inspection apparatus 101 includes a reflector 102 provided on the anti-imaging side of the preform 10, a visible light illumination 103 provided on the imaging side of the preform 10, and a visible light emitted from the visible light illumination 103. An imaging unit 4 that captures an image of the preform 10 that reflects light and outputs an image signal, and an inspection unit (not shown) that performs a defect inspection of the preform 10 based on the image signal are provided.
In addition, the preform 10 is imaged by the imaging means 4 in a state of revolving and rotating along the conveyance direction.

(Visible light illumination)
The visible light illumination 103 is illumination that emits visible light such as a fluorescent lamp, and is provided on the imaging side of the preform 10. Although not shown, the visible light illumination 103 has a substantially flat plate shape having a plurality of fluorescent lamps and reflectors. When viewed from above, the visible light illumination device 103 has a pair of opposed substantially L shapes. Visible light is irradiated to the preform 10 located in the region from the left-right direction and the imaging side.
In the present specification, the imaging side of the preform 10 refers to the side on which the imaging means 4 is located with respect to the arc-shaped trajectory passing through the centers of the plurality of preforms 10. The imaging side refers to the side where the imaging means 4 is not located with respect to the locus.

(reflector)
When viewed from above, the reflector 102 is a plate-like member that is curved corresponding to the locus of the preform 10 described above, and is usually painted white to suppress adverse effects of lens flare and background. .

(Imaging means)
The imaging unit 4 includes a screw unit imaging unit 41, a trunk unit imaging unit 42, and a bottom unit imaging unit 43 that respectively image the thread portion, the trunk portion, and the bottom portion of the preform 10.

(Inspection means)
The inspection unit is an information processing apparatus having a CPU, a memory, and the like, and receives image signals output from the screw unit imaging unit 41, the trunk unit imaging unit 42, and the bottom unit imaging unit 43. This inspection means sets a predetermined area as an inspection window for each image signal, performs binarization processing on a predetermined threshold value, etc., and if a visible defect is detected, the preform 10 is determined as a defective product. , A discharge signal for discharging the preform 10 is output to a discharge means (not shown).

  In order to inspect the preform using such a preform inspection apparatus 101, the preform 10 is irradiated with visible light from the imaging side, and the preform 10 on which the visible light is reflected is imaged. Then, based on the output image signal, a visible defect generated in the preform 10 is inspected.

However, in the above-described conventional example, undissolved gel, brown discoloration part, black discoloration part, solid foreign matter and the like generated in the preform 10 can be detected as visible defects, but are called white streaks that are not defects. Has also been detected as a defect. For this reason, there is a problem that the preform 10 with white streaks that can be used as a good product is rejected as a defective product, and the yield cannot be improved.
Here, the white streak is an approximately streak portion that occurs only at the bottom of the preform 10, and the resin of the preform 10 has turned pale white, and is generated inside the preform 10. The white streaks are not considered to be defects because they do not become a starting point of breakage when blow-molded and have no trouble in appearance.

  The present invention has been proposed in order to solve the above-described problems, and does not detect white streaks as defects, and undissolved gels, brown discoloration portions, black discoloration portions, solid foreign matters, and the like as defects. It is an object of the present invention to provide a preform inspection method and a preform inspection apparatus that can be selectively detected.

In order to solve the above problems, the present inventors conducted diligence, tests, and the like, and when imaging was performed using near infrared light transmitted through the preform 10, an undissolved gel, black color was detected without detecting white streaks. It was found that discolored parts and solid foreign matters can be detected.
However, when imaging was performed using transmitted near-infrared light, a new problem of not detecting the brown discoloration occurred, and measures were taken to deal with this problem.
Therefore, the present inventors can further test, etc., and can discriminate between white streaks and brown discoloration parts by imaging using visible light reflected by the preform 10 in addition to near infrared rays transmitted through the preform 10. Based on this finding, we developed a preform inspection method and a preform inspection device that can selectively detect undissolved gel, brown discoloration, black discoloration, and solid foreign matter without detecting white streaks. is there.

In order to achieve the above object, the preform inspection method of the present invention irradiates the preform with near infrared light and visible light, and simultaneously transmits the near infrared light transmitted through the preform and the visible light reflected by the preform. The preform receives light to image the preform, outputs an image signal, inspects the preform for a defect based on the image signal , and is detected as a defect when irradiated with visible light. When the defect is inspected, it is detected as a defect when the defect is inspected out of a portion where the resin of the preform is turned pale white and a portion turned brown. In addition, the irradiation intensity of the near infrared ray is set so that the white-discolored portion is not detected as a defect .

The preform inspection apparatus according to the present invention includes an infrared illumination that irradiates the preform with near-infrared rays, a visible-light illumination that irradiates the preform with visible light, a near-infrared ray that passes through the preform, and the preform. The visible light reflected by the laser beam is simultaneously received to image the preform, and the preform is inspected based on the imaging signal having sensitivity to visible light and near infrared rays for outputting an image signal and the image signal. An inspection means, both detected as a defect when irradiated with visible light, and not detected as a defect when irradiated with near-infrared light, and the part of the preform resin turned light white and turned brown When the defect is inspected, the brown part is detected as a defect, and the white part is detected as a defect. So as not to leave, the irradiation intensity of the near infrared of the infrared illumination is set, it is constituted to detect a defect of the preform.

According to the preform inspection method and the preform inspection apparatus of the present invention, since a preform in which white streaks that can be blow-molded as non-defective products are generated is not rejected as a defect, the yield can be improved. In other words, compared to the case in which preforms with white streaks are rejected and discarded, it is possible to prevent losses such as processing costs spent on discarded preforms and material costs of preforms. Etc. can be improved.
Further, since the preform is imaged by the transmitted near-infrared light and the reflected visible light, the occurrence of lens flare can be reduced as compared with the case where only the reflected visible light is used as in the conventional example described above. it can. Thereby, the inspection window can be widened, and the reliability of the inspection can be improved.

1A and 1B are schematic views for explaining a preform inspection apparatus according to an embodiment of the present invention, wherein FIG. 1A is a plan view, FIG. 1B is a cross-sectional view along AA, and FIG. ) Shows a BB cross-sectional view. 2A and 2B are schematic diagrams for explaining a preform inspection apparatus according to a conventional example. FIG. 2A is a plan view, FIG. 2B is a cross-sectional view taken along a line C-C, and FIG. -D shows a cross-sectional view.

(Preform inspection device)
In FIG. 1, the preform inspection apparatus 1 of the present embodiment irradiates from an infrared illumination 2 provided on the opposite side of the preform 10, a visible light illumination 3 provided on the imaging side of the preform 10, and the infrared illumination 2. The preform 10 through which the transmitted infrared rays are transmitted and the visible light irradiated from the visible light illumination 3 is reflected is picked up, the image pickup means 4 for outputting an image signal, and the preform 10 based on the image signal. An inspection means (not shown) for inspecting is provided.
Note that the preform 10 is a single-layer preform or a multilayer preform, and is imaged by the imaging unit 4 while revolving and rotating along the transport direction.

(Infrared illumination)
The infrared illumination 2 is an illumination that irradiates near infrared rays, and is provided on the non-imaging side of the preform 10. The infrared illumination 2 is substantially flat and has a plurality of infrared LEDs (not shown), and irradiates near infrared rays on the preform 10 located in the imaging region of the imaging means 4 from the non-imaging side. As a result, the near-infrared ray that has passed through the preform 10 enters the imaging means 4.
In addition, the infrared LED has a peak wavelength of about 800 nm to about 1100 nm, and the irradiated near-infrared light is invisible to the human eye, but a monochrome CCD camera described later has a lower sensitivity than visible light. Also, it has sensitivity to the near infrared rays.
Furthermore, the use of near infrared rays has the effect of reducing the occurrence of lens flare, the inspection window can be widened, and the reliability of inspection can be improved.

As will be described later, the preform inspection device 1 selectively captures undissolved gel, black discoloration, solid foreign matters, and the like without detecting white streaks when imaging using near infrared light transmitted through the preform 10. It can be detected.
However, if the preform inspection apparatus 1 captures an image using only the transmitted near-infrared light, it cannot detect the brown discoloration portion.

(Visible light illumination)
The visible light illumination 3 is illumination that emits visible light such as a fluorescent lamp, and is provided on the imaging side of the preform 10. The visible light illumination 3 is substantially flat and has a plurality of fluorescent lamps and reflectors, not shown, and has a pair of opposed substantially L shapes when viewed from above. Visible light is irradiated from the imaging side to the preform 10 located in the imaging region.
The visible light illumination 3 is not limited to the structure described above.

  As will be described later, the preform inspection apparatus 1 picks up an image using visible light reflected by the preform 10 in addition to the near-infrared light transmitted through the preform 10, so that white streaks and brown discoloration portions are identified. It is possible to selectively detect undissolved gels, brown discolored portions, black discolored portions, solid foreign matters and the like without detecting white streaks.

(Imaging means)
The imaging unit 4 includes a screw unit imaging unit 41, a trunk unit imaging unit 42, and a bottom unit imaging unit 43 for imaging the thread portion, the trunk unit, and the bottom unit of the preform 10, respectively. Usually, it is a monochrome CCD camera and has sensitivity to visible light and near infrared rays.

(Inspection means)
The inspection unit is an information processing apparatus having a CPU, a memory, and the like, and receives image signals output from the screw unit imaging unit 41, the trunk unit imaging unit 42, and the bottom unit imaging unit 43. This inspection means sets a predetermined area as an inspection window for each image signal, performs binarization processing for a predetermined threshold value, etc. When an abnormality is detected, the preform 10 is determined to be defective, and the preform A discharge signal for discharging 10 is output to a discharge means (not shown).

  The abnormality is a defect that should be visually recognized, specifically, an undissolved gel, a brown discolored portion, a black discolored portion, a solid foreign matter, and the like, and is a dark portion when displayed on a monitor. That is, when inspecting the visible defect, the preform inspection apparatus 1 of the present embodiment detects undissolved gel, brown discoloration portion, black discoloration portion and solid foreign matter as defects, and white stripes usable as non-defective products are detected. Since the generated preform 10 is not rejected as a defective product, the yield can be improved.

Next, the preform inspection method of this embodiment will be described.
The preform inspection method of the present embodiment is an inspection method performed using the preform inspection apparatus 1. First, the infrared illumination 2 irradiates the preform 10 with near infrared rays from the non-imaging side, and the visible light illumination 3. However, the preform 10 is irradiated with visible light from the imaging side.
Further, as described above, the preform 10 revolves and rotates along the conveyance direction.

Here, preferably, as adjustment and setting of the preform inspection apparatus 1, first, imaging is performed so that the inspection unit detects the brown discoloration portion with the infrared illumination 2 turned off and the visible light illumination 3 turned on. Adjust the iris (aperture) of the means 4, then turn on the infrared illumination 2 (the visible light illumination 3 is kept on), and increase the near-infrared irradiation intensity from low intensity to high intensity. Infrared illumination 2 may be set to an intensity that does not detect white streaks and detects undissolved gel, brown discoloration, black discoloration, and solid foreign matter. This adjustment and setting is usually performed using a limit sample or the like before the start of inspection or during periodic inspection.
In this way, adjustment and setting of the preform inspection apparatus 1 can be performed easily and appropriately, and productivity and inspection reliability can be improved.
In addition, irradiation intensity means the light beam per unit solid angle (a unit is a watt / steradian).

  Next, the image pickup means 4 picks up the preform 10 through which the near infrared ray irradiated from the infrared illumination 2 is transmitted and the visible light irradiated from the visible light illumination 3 is reflected, and outputs the image signal to the inspection means. To do.

The inspection means inspects a visible defect generated in the preform 10 based on the image signal.
This inspection means performs binarization processing on the image signal, inspects whether or not an abnormality (usually a darkly displayed portion) is not detected in the inspection window, and if detected, a preform 10 is judged as a defective product, and a discharge signal is output to a discharge means (not shown).
That is, when the preform inspection method of the present embodiment inspects a visible defect, an undissolved gel, a brown discoloration portion, a black discoloration portion, and a solid foreign matter are selectively detected as defects, and the preform 10 is generated. White streaks are not detected as defects. Thereby, so-called “waste splash” can be prevented and the yield can be improved.

  As described above, according to the preform inspection apparatus 1 and the preform inspection method of the present embodiment, the preform 10 with white streak that can be used as a non-defective product is not rejected as a defective product, so that the yield is improved. It is possible to improve economy and productivity.

As described above, the preform inspection method and the preform inspection apparatus of the present invention have been described with reference to the preferred embodiments. However, the preform inspection method and the preform inspection apparatus according to the present invention are limited to the above-described embodiments. However, it goes without saying that various modifications can be made within the scope of the present invention.
For example, in the above-described embodiment, when inspecting a visible defect, an undissolved gel, a brown discoloration part, a black discoloration part, and a solid foreign matter are selectively detected as defects. It is not limited to the object. For example, it can be applied to various objects that can be identified by near-infrared rays that have passed through the object to be inspected or not identified and that they can be identified by visible light reflected by the object to be inspected or not. can do.

1, 101 Preform inspection device 2 Infrared illumination
3, 103 Visible light illumination
4 Imaging means
41 Imaging means for screw part
42 Imaging unit for trunk 43 Imaging unit for bottom

Claims (3)

Irradiate the preform with near infrared and visible light,
Simultaneously receiving near-infrared light transmitted through the preform and visible light reflected by the preform to image the preform, and output an image signal,
Based on the image signal, inspect the preform for defects ,
Of the parts that are detected together as defects when irradiated with visible light, and are not detected as defects when irradiated with near infrared rays, the resin of the preform has turned pale white and the part turned brown, When inspecting a defect, the irradiation intensity of the near infrared ray is set so that the brown-colored portion is detected as a defect and the white-colored portion is not detected as a defect. A characteristic preform inspection method. The preform inspection method according to claim 1, wherein the near infrared ray is emitted from an infrared LED, and the visible light is emitted from a fluorescent lamp.
Infrared illumination that irradiates the preform with near infrared radiation,
Visible light illumination for irradiating the preform with visible light;
An imaging means having sensitivity to visible light and near-infrared light that outputs the image signal while simultaneously receiving near-infrared light transmitted through the preform and visible light reflected by the preform to image the preform;
Inspecting means for inspecting the preform based on the image signal,
Of the parts that are detected together as defects when irradiated with visible light, and are not detected as defects when irradiated with near infrared rays, the resin of the preform has turned pale white and the part turned brown, When inspecting a defect, the near-infrared irradiation intensity of the infrared illumination is set so that the brown-colored part is detected as a defect and the white-colored part is not detected as a defect,
A preform inspection apparatus for detecting defects in the preform.

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