JPS6057534B2 - How to sort glass bottles with defects in the mouth - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sorting glass pins, and more particularly to a method for automatically sorting out glass pins with a defective mouth portion on a production line.

It is known that various defects occur in glass bits during the production process.

One of the typical defects is a minute rack called a crack in the industry. These cracks are difficult to detect in appearance, and glass pins with cracks cannot be reliably sorted out without a skilled inspector.
In particular, if there is a crack in the opening of the glass pin, the bottle may be chipped when the nozzle of the filling machine comes into contact with the bottle.
Otherwise, the entire pin may be destroyed.
Also, even if it does not break during filling, there is a risk that a small amount of outside air will enter through cracks in the bottle after the cap is applied and cause the contents to change in quality. Glass pins are highly disliked, and pins with cracks at the mouth must be completely screened out before being shipped from the bottle factory. Many methods have been developed to automatically inspect cracks in glass pins, and each method has been put into practical use according to its characteristics.Among them, there are two types of methods for automatically inspecting cracks in glass bottles: non-contact and contact. Both have been put into practical use.

The non-contact inspection method irradiates the glass bin with visible light, infrared rays, laser light, etc., and cracks cause these light rays to appear. The reflected light is detected by a photoelectric conversion element. However, this type of inspection method has the disadvantage that the inspection accuracy varies widely depending on the angle at which the crack enters the bottle. That is, if the direction of the crack is close to parallel to the direction of the irradiated light beam, detection becomes impossible because almost no reflection occurs. Therefore, if the direction of the crack is assumed in advance, sufficient inspection accuracy can be obtained, but if the crack is in a random direction, sufficient inspection accuracy cannot be obtained. Unavoidable. On the other hand, the contact type inspection method scans the surface of the glass pin while pressing the contact against the surface of the glass pin and inspects for the presence of cracks, so the rate of inspection accuracy changes depending on the direction of the crack. Although the contactors are small, there is a drawback that the inspection accuracy decreases due to wear of the contacts, and there is a disadvantage that a lot of effort is required for maintenance and management of the inspection device.

Therefore, there has been a demand for a non-contact inspection method for glass bins that is capable of achieving constant inspection accuracy regardless of the direction of cracks. While conducting repeated studies to solve the above technical problem, the present inventor learned that there is a method that does not directly detect the presence or absence of cracks, but instead judges the presence or absence of cracks based on the strength of the glass pin. Ivy.

This method normally applies high pressure to the inside of the glass pins, and destroys the pins whose strength has decreased due to the presence of cracks or other defects, thereby selectively removing them. However, it has been found that this method is effective when cracks exist in the body and bottom of the glass pin, but not when cracks exist in the mouth of the glass pin.
This is because the mouth of a glass pin generally has a small diameter and a large wall thickness, has greater mechanical strength than the body, and has a nozzle that injects high-pressure fluid into the pin. This is because the pin is often sealed, so even if there is a small rack, it is less likely to break due to the pressure applied inside the pin. The present invention solves the drawbacks of the prior art as mentioned above,
This was done with the purpose of providing a method for sorting and removing glass pins that have cracks at their mouths, regardless of the direction of the cracks.In order to break and sort out defective pins, high pressure is applied inside the pins. Although this method is similar to the method of injecting fluid, the selection principle is completely different.

That is, the present invention heats the opening of the glass pin to a high temperature below its softening point, then blows cooling air onto both the inner and outer surfaces of the glass pin to generate distortion in the glass pin, and applies a weak external force to the opening. The summary of this paper is a method for sorting glass pins with defects in the mouth, which is characterized by selectively destroying glass pins with defects such as cracks in the mouth. It is something to do. The present invention will be explained in more detail below with reference to Examples.

The drawings all show embodiments of the present invention, and the first
The figure shows the heating process of the glass pinhole section. FIG. 2 is a sectional view showing the process of blowing cooling air.

The device used in this example is an improved nozzle part of the device used for wind-cooling strengthening of glass cups, plates, bowls, etc., for use with glass pins. Since the device is well known, only its essential parts are illustrated. The apparatus used in the embodiment consists of a roller chain suspended between a pair of large sprockets 1 (FIG. 2), the link plates 2 of which are shown in the drawing.

A shaft 3 is rotatably provided at a portion of the chain corresponding to a pin, and moves between the sprockets as the chain moves. A holder 5 that holds the bottom of the glass pins 4 to be sorted is fixed to the upper end of the shaft 3, while a small sprocket 6 is fixed near the lower end of the shaft 3, and small chains 7, 8, etc. Since the glass pins 4 are engaged with each other and rotate the shaft 3, the glass pins 4 move between the large sprockets while rotating. In the part where the glass pin 4 to be sorted moves linearly between the sprockets, multiple sets of burners 9 and 10 are provided as shown in Fig. 1, and the glass pin 4 passes under these burners while rotating. During this process, the mouth part is heated to a temperature 70 to 800C lower than the softening point.

For example, the softening point of ordinary soda lime glass is around 730°C, so the opening of the glass pin 4 is 650~660°C.
It is best to heat it up to . Furthermore, if the temperature approaches the softening point, there is a risk of deformation, and conversely, if the temperature is too low, sufficient strain cannot be formed, and a glass pin with a defect in the opening cannot be completely removed. When the glass pin 4 with its mouth heated in this manner comes to the large sprocket 1, the nozzle 12 descends from the disk 11 mounted coaxially with the sprocket 1.

This nozzle 12 is attached to the tip of a hollow shaft 13, and this center shaft 13 has a cam follower 14 at its upper end, and is slid in the vertical direction by a rail cam 15. When the hollow shaft 13 descends as shown in FIG. 2, compressed air flows from the distributor 17 through the hole 16, and the nozzle 1
Cooling air will blow out from 2. The nozzle 12 is inserted into the mouth of the glass pin 4 and consists of an inner nozzle 18 that cools the mouth from the inside, and an outer nozzle 19 that cools the mouth of the glass pin 4 from the outside. Each of these nozzles is provided with a large number of fine holes to uniformly cool the mouth of the glass pin 4. During this time, the glass pin 4 continues to rotate. As a result, the opening of the glass pin 4 changes from a temperature of about 650°C to 1
As it is rapidly cooled to around 00°C within 15 seconds, a large compressive stress is generated on the surface due to the principle of wind cooling strengthening, and on the other hand, a large tensile stress is generated in the center, causing distortion. be done. If there are no defects at the mouth of the glass pin, this strain will be uniformly balanced on the glass surface, so the glass pin will not be damaged, and on the contrary, the heat resistance and mechanical strength will decrease. The result will be an improvement.

However, there are cracks in the mouth. If a defect exists, the strain distribution will be disturbed in that part, and the strain will be in an unbalanced state. And if the crack is deep and its tip reaches the tensile stress layer caused by wind cooling, the glass pin will not react when a slight external force is applied to it, or when no external force acts on it. Even if this happens, the tip of the crack will become the starting point and the glass pin will break. In addition, even if the crack is shallow and does not reach the tensile stress layer, the value of compressive stress formed by wind cooling is maximum at the glass surface and rapidly decreases toward the inside, so the tip of the crack is Considering this, the compressive stress value becomes extremely small compared to the case without cracks, and the resistance force when an external force acts on the glass pin naturally becomes small.
Therefore, by applying a small external force to the mouth of the glass pin, it is possible to sort out even relatively shallow cracks. Note that as a device for applying an external force, a type in which a glass pin is continuously struck with a small rotating hammer is known, but other suitable devices may be used as appropriate.

Through the above process, the glass pin with a defect in the mouth part is destroyed by itself or by a slight external force, and only the glass pin with no defect in the mouth part and strengthened by generating compressive stress in the mouth part remains and is shipped. It will be done. It happens.

In the above explanation, it is assumed that the air pressure supplied to the inner nozzle 18 and the air pressure supplied to the outer nozzle 19 are equal, but if higher pressure air is supplied to the inner nozzle through another distributor, the air pressure will be even higher. Good results can be obtained.

This is because the inner surface of the mouth of the pin is less likely to be cooled than the outer surface, and when the inner and outer surfaces are cooled with equal air pressure, the inner and outer surfaces tend to be unbalanced in strain. As a result, there is a risk that even non-defective glass pins will be destroyed. According to research by the present inventors, the pressure of the air for cooling the inner surface is 0.3 to 3.0k91c! is the range of i,
The best results are obtained when the pressure is about 2 to 5 times the pressure of the air for cooling the external surface. The present invention has the following effects.

1) Glass pins with defects such as cracks on the mouth can be automatically selected.

In particular, the accuracy of sorting does not change depending on the angle of the crack as in the case of optical inspection, and there is no trouble caused by contact wear as in the case of contact inspection, so the same level of accuracy is always maintained. Sorting accuracy can be obtained. ). ) In the method of injecting high-pressure fluid into the inside of the glass pin to destroy a cracked glass pin, the glass pin hole part has a large wall thickness and is sealed by a high-pressure fluid injection nozzle, so cracks may occur in the glass pin hole part. As mentioned above, it is difficult to sort even if

However, the method of the invention makes it possible to avoid these drawbacks. This is because the strain caused by air cooling is more likely to be formed in a thicker part, so that the relatively thick mouth part is rather advantageous for the present invention. In other words, this is where the difference between a method that applies stress from the outside and a method that generates stress within the glass itself appears. 3) Generally, it is common knowledge that glass pins that have undergone an inspection process lose some of their strength due to handling for inspection, external force loading, etc.

However, in the present invention, the mouth portion of the glass pin is strengthened by air cooling, so the strength of the glass pin that does not break is much higher than that of the glass pin before the test. In particular, in a test in which a glass pin was dropped onto a concrete floor with its mouth facing downward and the height at which it was broken was measured, the glass pin before the test was broken in an average of 1 drop, whereas the glass pin that had undergone the process of the present invention was broken in one drop on average. The glass pins did not break down to an average length of 24 cm, indicating that their strength was improved. Therefore, the glass pins shipped through the process of the present invention can withstand impact from the nozzle of the filling machine well, and can also help prevent troubles during filling. As described above, the present invention applies the air-cooling strengthening method to the mouth of the pin and cleverly utilizes this to select glass pins with defects in the mouth, and we believe that it has great practical value. .

[Brief explanation of the drawing]

The drawings all show embodiments of the present invention, and FIG. 1 is a sectional view showing a heating process, and FIG. 2 is a sectional view showing a cooling process.

Claims (1)

[Claims] 1. After heating the mouth of a glass bottle to a high temperature below the softening point, cooling air is blown onto both the inner and outer surfaces of the mouth of the glass bottle to generate distortion in the mouth of the glass bottle, and a weak external force is applied to the mouth of the glass bottle to cause the mouth to become distorted. A method for sorting glass bottles with a defect in the opening, characterized by destroying glass bottles with the defect.