JPH0260137B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for destructively inspecting glass bottles. (Prior art) Glass bottles, such as glass bottles for carbonated beverages, which are subject to large internal pressures during use, must undergo strength testing on all glass bottles at a bottle making factory. Destructive testing methods have been adopted, including one in which a pressure rod is inserted from the mouth of a glass bottle and the bottom of the glass bottle is pressed. However, when using the former method, as shown in Figure 4, a relatively large tensile stress is generated in the center of the body, so glass bottles with weak defects in the center of the body cannot be reliably rejected. However, defects in other parts cannot be detected, and when using the latter method, as shown in Figs. Regarding the surface, relatively large tensile stress occurs at the bottom corners, so glass bottles with defects in these areas can be reliably eliminated, but defects in other areas cannot be detected. Therefore, even if glass bottles are inspected using a combination of these two methods, glass bottles with defects on the shoulders or lower part of the body cannot be detected, and glass bottles that pass the inspection cannot be detected after being filled with contents. This caused problems such as damage. (Objective of the Invention) The present invention solves these conventional problems and provides a destructive inspection of glass bottles that can reliably detect and eliminate glass bottles that have defects with low strength in the shoulder or lower part of the body. It was completed for the purpose of method. (Structure of the Invention) The present invention is characterized in that a vertical impact load is applied to the top surface of the mouth of a glass bottle placed on a table, and a large tensile stress is generated in the shoulder and lower part of the glass bottle. This will be explained in detail below with reference to the illustrated embodiments. In the embodiment shown in FIG. 1, a glass bottle 1 to be inspected is placed on a horizontal stand 10 made of hard resin, and a vertical impact load is applied by dropping a weight 11 onto the top surface 2 of the mouth. is added. A portion 12 of the weight 11 in contact with the mouth top surface 2 of the glass bottle 1 is made of hard resin to prevent the mouth top surface 2 from being scratched. The weight 11 is supported by a vertical guide rod 13 so as to be able to move up and down, and after the weight 11 is raised to a predetermined height by winding up a string 14 attached to one end with a wheel 15 with a ratchet, the ratchet is removed and the ratchet is lifted. The attached wheel 15 is rotated in the opposite direction to drop the weight 11 onto the top surface 2 of the mouth of the glass bottle 1. The weight of the weight 11 should be set according to the shape and wall thickness of the glass bottle 1 to be inspected, but the weight shown in the drawing is 170 g, the internal capacity is 500 c.c., the total length is 138 mm, and the average glass wall thickness is 2.3 mm. 13.2Kg to inspect glass bottles
The weight of the sample was used. In addition to the method described above, various methods can be used to raise and lower the weight 11, such as using a rotating cam or pushing it up using a cylinder.
In either case, it is necessary to align the central axis of the weight 11 and the central axis of the glass bottle 1 so that no eccentric load is applied to the glass bottle 1. In addition, machine 1
It is preferable to provide a through hole 16 in the center of the glass bottle 1 to facilitate the removal of fragments when the glass bottle 1 is broken. In this way, when a vertical impact load is applied to the top surface of the mouth of glass bottle 1, stress as shown in Figure 2 is generated per unit load on the outer surface of glass bottle 1, and stress is generated on the inner surface of glass bottle 1 as shown in Figure 2. The stress shown in Figure 3 is generated. In these figures, the solid line is the stress in the circumferential direction, and the broken line is the stress in the axial direction. As is clear from these stress distribution diagrams, strong tensile stress in the circumferential direction is generated on the outer circumferential surface of the shoulder 3 and the lower body 4 of the glass bottle 1 due to the impact load, and the shoulder 3 of the glass bottle 1
Strong tensile stress is also generated on the inner circumferential surface of the bottom corner portion 5, and the glass bottle 1 having defects with low strength in these portions will surely be destroyed by the tensile stress. Further, since the tensile stress caused by such an impact load acts only momentarily, the strength of the glass bottle 1 is hardly deteriorated, and the contradiction of strength reduction due to strength testing can be avoided. Next, 150 glass bottles 1 were prepared, and the first group was not scratched, and the second group was made with a vertical scratch of 4 mm in length using a carbide grindstone on the outer surface at a height of 5 mm from the bottom. , a third group with similar damage to the part 10mm from the bottom, a fourth group with similar damage to the part 20mm from the bottom, and a fifth group with 30 pieces of damage to the part 30mm from the bottom were created. . Destructive tests were conducted on the glass bottles in each group while increasing the falling distance of the weight 11, and the number of bottles broken is shown in the table below.

[Table] As is clear from the table above, the falling distance of the weight is
If it is set to 10 cm, an intact glass bottle will not be destroyed at all, and all glass bottles that have been damaged in the lower part 4 within a range of 10 to 20 mm from the bottom can be reliably destroyed. (Effects of the Invention) As is clear from the above description, the present invention is capable of reliably destroying and removing glass bottles with defects in the shoulder or lower part of the body, which could not be inspected in the past. In addition, since the capping machine applies a longitudinal impact load to the glass bottle that is similar to the axial load applied to the glass bottle, the glass bottles inspected by the method of the present invention have no impact during capping. It is effective in preventing troubles on the filling line. Moreover, the present invention hardly causes any deterioration in the strength of the glass bottle due to the application of a load, so it greatly contributes to the industry as a solution to the drawbacks of conventional destructive testing methods for glass bottles.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention, and FIGS. 2 and 3 are graphs showing the stress distribution generated in a glass bottle when the strength of the glass bottle is tested by the method of the present invention. 4, 5, and 6 are graphs showing the stress distribution generated in a glass bottle when the strength of the glass bottle is tested by the conventional method. 1: Glass bottle, 2: Top of mouth, 3: Shoulder, 4: Lower body.

Claims (1)

[Claims] 1. A method for destructively inspecting glass bottles, which is characterized by applying a vertical impact load to the top surface of the mouth of a glass bottle placed on a stand, and generating large tensile stress in the shoulders and lower body of the glass bottle.