JP2010008305A - Strain inspection device of glass bottle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate and automate the inspection of the permanent strain of a glass bottle caused by the insufficiency of a slow cooling process. <P>SOLUTION: The problem is solved by the following process: Polarizing plates are respectively provided under the bottom part of the glass bottle and above the mouth part of the glass bottle in opposed relationship so that the directions x and y of the polarizing surfaces of them cross each other at a right angle and a light source is provided on the side opposite to the bottle of one polarizing plate while a line sensor camera is provided on the side opposite to the bottle of the other polarizing plate. The bottom part of the rotating bottle is irradiated with light from the light source while the light transmitted through one polarizing plate, the bottom part of the bottle and the other polarizing plate is detected by the line sensor camera and the strain of the bottle is inspected on the basis of the detection quantity of light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a glass bottle distortion inspection apparatus suitable for automatically inspecting permanent distortion (residual stress) remaining in a glass of a glass bottle after molding due to an insufficient slow cooling process. .

Known methods for inspecting glass bottles for scratches and distortion include the crossed Nicols method and the Senarmont method.
In the crossed Nicols method, as shown in the following Patent Documents 1 to 3, one polarization is applied to a glass bottle between two polarizing plates provided so that the directions x and y of the polarization planes are orthogonal to each other. Light is irradiated from the outside of the plate, light is received by a light receiving element outside the other polarizing plate, and wrinkles such as scratches and distortion are inspected by a change in the voltage. If there is no wrinkle, the light passing through the bottle is not disturbed, and the light beam hardly reaches the light receiving element due to the action of the polarizing plate whose polarization plane is orthogonal, but if there is a wrinkle, the light is scattered or the polarization direction is changed. As a result, the light reaches the light receiving element and the presence of soot can be known.
This method is suitable for inspection automation, but due to various factors, the correlation between the voltage output from the light receiving element and the physical quantity of the soot (for example, internal stress) is not necessarily good, and is not suitable for quantitative measurement. It had been. Therefore, when the difference between the normal value and the abnormal value is very large, the threshold value is set to be considerably larger than the normal value, and this is used as a simple inspection method for roughly detecting the abnormal value.

The Senalmon method is an inspection method for performing quantitative measurement of strain. The angle scale of the analyzer is adjusted to 0 degree, and an observation object is put in a place where the entire visual field appears dark and black, and the position where distortion is to be quantified is searched and fixed while rotating. Next, the analyzer rotation frame is slowly rotated to read the angle at the darkest position. The amount of distortion is obtained by applying the rotation angle to a calculation formula.
Therefore, this method needs to be operated by the measurer, and there may be individual differences depending on the measurer, and is not suitable for automation of the inspection.
JP 49-29879 A JP 49-51995 A Japanese Utility Model Publication No. 54-124592

  The present invention is a glass bottle distortion inspection apparatus using the crossed Nicols method for inspecting permanent distortion caused by an insufficient slow cooling process. It is an object of the present invention to improve the correlation between (stress) and to set an appropriate threshold to enable accurate inspection.

[Claim 1]
The present invention provides a polarizing plate on the lower side of the bottom of the glass bottle and the upper side of the mouth so that the polarization plane directions x and y are orthogonal to each other, and a light source is provided on the opposite side of the one polarizing plate to the bottle. A line sensor camera is provided on the side of the polarizing plate opposite to the bottle to irradiate light to the bottom of the rotating bottle from the light source, and the light transmitted through the one polarizing plate, the bottom of the bottle, and the other polarizing plate is lined. An inspection device that receives light with a sensor camera and inspects bottle distortion based on the amount of light received,
The glass bottle distortion inspection apparatus is characterized in that a direction of a light receiving element array of the line sensor camera is directed in a radial direction of the bottle and is inclined with respect to directions x and y of the polarization plane.

[Claim 2]
Further, according to the present invention, the direction of the light receiving element array of the line sensor camera is coincident with a straight line L inclined by 45 ° with respect to the directions x and y of the polarization plane, or inclined within 30 ° with respect to the straight line L. The glass bottle distortion inspection apparatus according to claim 1.

Since a large permanent strain (caused by an insufficient slow cooling process) that affects the strength of the glass bottle is generated at the bottom of the bottle, the present invention examines the strain at the bottom of the bottle.
When the bottom of the glass bottle is inspected by the crossed Nicols method, as shown in FIGS. 2 and 3, a cross-shaped dark portion 12 (shaded portion) is generated in the same direction as the polarization plane direction xy of the polarizing plate. This is because when the polarized light is transmitted through the part with the bottom of the bottle, if the plane of polarization is in the diameter direction of the part of the bottle, the direction of the plane of polarization hardly changes even if there is a large distortion. It is done.
As shown in FIG. 2, when the direction xy of the polarization plane of the polarizing plate and the light receiving element array of the line sensor camera are set in the same direction, the dark portion 12 is measured by the line sensor camera, and accurate measurement cannot be performed. The correlation between the voltage output from the sensor camera and the amount of distortion (internal stress) becomes worse.

As shown in FIG. 3, by inclining the direction xy of the polarization plane of the polarizing plate and the light receiving element array of the line sensor, the correlation between the voltage output from the line sensor camera and the amount of distortion (internal stress) is improved.
Most preferably, the light-receiving element array of the line sensor camera coincides with the straight line L inclined by 45 ° with respect to the directions x and y of the plane of polarization. It is possible to accurately inspect the vicinity of the important bottle bottom. If it exceeds 30 degrees, there is a possibility that the vicinity of the outer periphery of the important bottle bottom may be related to the dark portion 12, which is not preferable.

There are permanent strains (residual stress) and temporary strains (thermal stress) as the glass bottles are slowly cooled. Residual stresses and thermal stresses are not yet cooled in the downstream of the slow cooling furnace. However, only the residual stress remains when cooled to room temperature.
As a result of simulating the magnitude of strain in the slow cooling process of the glass bottle, the peak of permanent distortion (residual stress) occurs in the outer peripheral part of the inner surface of the bottle bottom (near the inner hem corner part 4), and the permanent distortion in the central part is I found it very small.
In FIG. 3, the central portion 12 on the bottom surface of the bottle is a dark portion. However, as described above, since the permanent distortion at the central portion is very small, there is no hindrance to the distortion inspection.

  Since the glass bottle distortion inspection apparatus of the present invention uses the orthogonal Nicol method, it is easy to automate. In addition, since there is a good correlation between the voltage output from the light receiving element and the amount of distortion (internal stress), it is possible to accurately inspect by setting the threshold value appropriately.

  Hereinafter, the present invention will be described in detail with reference to the drawings relating to the embodiments. 1 is a side view of the glass bottle distortion inspection apparatus of the embodiment, FIGS. 2 and 3 are schematic views of the glass bottle viewed from above the polarizing plate 9, and FIG. 4 is a measurement result of the inspection apparatus of the embodiment and the Senarmon method. It is a related figure of a measurement result.

The glass bottle distortion inspection apparatus shown in FIG. 1 includes a support 5, a rotation driving roller 6, a light source (surface light source) 7, polarizing plates 8 and 9, and a line sensor camera 10.
The glass bottle 1 that has moved from the outlet of the slow cooling furnace by a conveyor (not shown) is taken into the support base 5 and is rotatably supported, and is rotated by the rotation driving roller 6. Such a support base and a rotation driving roller are well known. A line sensor in which a polarizing plate 8 is provided on the lower side of the glass bottle bottom 2, a surface light source 7 is provided on the lower side (the side opposite to the glass bottle), and a polarizing plate 9 is attached above the glass bottle opening 3. A camera 10 is provided. Therefore, the line sensor camera 10 is located on the side opposite to the bottle of the polarizing plate 9. The directions x and y of the polarization planes of the polarizing plates 8 and 9 are orthogonal to each other. The bottle bottom 2 rotating from the light source 7 is irradiated with light, the light transmitted through the polarizing plate 8, the bottle bottom 2 and the polarizing plate 9 is received by the line sensor camera 10, and the distortion of the bottle is inspected by the amount of the received light. .

  As shown in FIG. 3, the direction S of the light receiving elements in the line sensor camera 10 coincides with the direction of the straight line L inclined 45 ° with respect to the directions x and y of the polarization planes of the polarizing plates 8 and 9. Reference numeral 11 in FIG. 3 denotes an area (camera light receiving area) where the light receiving element of the line sensor camera 10 receives light. Reference numeral 12 denotes the dark portion. Since the camera light receiving area 11 is not related to the dark part 11 (particularly near the outer periphery of the bottle bottom, which is important), an accurate inspection can be performed.

  The line sensor camera 10 receives light while the glass bottle 1 rotates at least once, and transmits the result to a control device such as a computer or a recording device (not shown). The control device is based on a preset threshold value. If it is determined that the product is defective, a rejection signal is sent to a well-known rejection device (not shown), and the rejection device excludes the defective product from the line. Such determination means and exclusion means are well known.

Figure 4 shows the measurement of eight glass bottles cooled to room temperature (bottles for ripening and storing fruit wine such as plum wine, the same shall apply hereinafter) using both the apparatus of the example (orthogonal Nicol method) and the Senarmon method. The result is shown in a graph. In the figure, the measurement result of the orthogonal Nicol method represents the amount of transmitted light.
The unit “nm” of the measurement result of the Senalmon method is the magnitude of birefringence (phase difference) and is proportional to the stress (photoelasticity).
As a result, the correlation coefficient between the measured value of the apparatus of this example and the Senalmon method is 0.984, which is a very good correlation, and the difference between the measurement results is about the measurement error. It was proved that measurement was possible.

The output signal of the light receiving element of the line sensor camera is sent to a control device such as a computer, and pass / fail judgment is performed.
The threshold value for the pass / fail determination may be set as appropriate so as to ensure the required quality, but can be set as follows, for example.
(1) When a bottle (non-defective product) that does not cause distortion at the peak position of the residual stress is prepared, and the output of the light receiving element at the peak position is A, A + α is set as the threshold value 1, and the light received by detecting the output exceeding this The element is an abnormality detection element.
(2) The threshold value 2 for the number of abnormality detection elements is set appropriately, and if the number of abnormality detection elements exceeds the threshold value 2, it is determined as a defective product.
For example, when the output A is 120 (/ 256), if 140 (/ 256) is set to the threshold value 1 and the threshold value 2 is set to 500, 140 (/ 256) during the inspection (at least during one rotation of the bottle). ) When the number of light receiving elements that output a numerical value exceeding 500 exceeds 500, it is determined as a defective product.

It is a side view of the glass bottle distortion inspection apparatus of an Example. It is a schematic diagram of the state which looked at the glass bottle from the upper direction of the polarizing plate. It is a schematic diagram of the state which looked at the glass bottle from the upper direction of the polarizing plate. It is a related figure of the test | inspection apparatus measurement result of an Example, and a Senalmon method measurement result.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass bottle 2 Bottom part 3 Mouth part 4 Inner hem corner part 5 Support stand 6 Rotation drive roller 7 Light source 8 Polarizing plate 9 Polarizing plate 10 Line sensor camera 11 Camera light-receiving area 12 Dark part

Claims (2)

A polarizing plate is provided on the lower side of the bottom of the glass bottle and the upper side of the mouth so that the polarization plane directions x and y are orthogonal to each other, a light source is provided on the opposite side of the one polarizing plate to the bottle, and the other polarizing plate is provided. A line sensor camera is provided on the opposite side of the bottle, and the bottom of the bottle rotating from the light source is irradiated with light, and the light transmitted through the one polarizing plate, the bottom of the bottle, and the other polarizing plate is received by the line sensor camera. And an inspection device for inspecting bottle distortion based on the amount of received light,
A glass bottle distortion inspection apparatus, wherein a direction of a light receiving element array of the line sensor camera faces a radial direction of the bottle and is inclined with respect to directions x and y of the polarization plane.   2. The direction of the light receiving element array of the line sensor camera coincides with a straight line L inclined by 45 ° with respect to the directions x and y of the polarization plane, or is inclined within 30 ° with respect to the straight line L. Glass bottle distortion inspection equipment.