JPH02269663A - Adjustment of torque for opening cap of container made of synthetic resin - Google Patents

Abstract

PURPOSE:To allow adjusting the torque for opening a cap mounted on a mouth by a method wherein a chamfer is formed at the inside corner of a top open end of a mouth so as to adjust the area of a cap sealing material in contact with the top open end. CONSTITUTION:A chamfer 9 is formed at the inside corner of an open end 3 of a mouth 2 to adjust the area of the open end in contact with a cap sealing material 8 when a cap 6 is screwed on the mouth 2, so that the torque for opening the cap for the first time is adjusted. That is, the area of the open end is reduced as a larger chamfer is formed, and the compression stress on the area of the cap seal material in contact with the open end increases, which is produced corresponding to the compression load from the open end 3 when the cap 6 is screwed on the mouth 2. On the other hand, the compression stress on the area of the cap seal material 8 in contact with the open end 3 is not increased so much with a little chamfer. Therefore, the torque for opening the cap 6 is adjusted corresponding to the size of the chamfer 9 formed on the open end 3.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for adjusting the opening torque of a cap attached to the mouth of a synthetic resin container, particularly a polyethylene terephthalate resin bottle (hereinafter referred to as a PET bottle). .

(Prior art) In general, when opening a container made of synthetic resin from the mouth, if the cap is tightened too tightly to the mouth, the cap becomes difficult to open; If it is too loose, the contents inside the container may leak or give a feeling of uneasiness as if the container is leaking. For this reason, the opening torque of the cap has conventionally been adjusted, and is usually adjusted based on the capper conditions. In the case of an aluminum cap, this adjustment method is performed by adjusting top pressure and side pressure, and tightening of a threaded portion formed on the inner surface of the cap is performed by adjusting torque.

However, in the case of any cap, the above adjustment method requires stopping the production line midway through and making adjustments, and the adjustment is very time-consuming.
There was a problem in that it led to a decrease in manufacturing efficiency. In addition, in the case of a synthetic resin cap, the opening torque can also be adjusted by changing the material and thickness of the cap sealing material provided on the inner surface of the cap. Since the determination of the material and thickness is influenced by the temperature, there is a problem in that it is very difficult to freely adjust the opening torque.

(Problems to be Solved by the Invention) The present invention is a method for adjusting the opening torque of a synthetic resin container, which eliminates such inconveniences and allows the adjustment of the opening torque of the cap of a synthetic resin container in a simple manner. is intended to provide.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a threaded portion in the circumferential direction on the outside of the mouth, and a cap is screwed onto the mouth from the outside and tightened. In a method for adjusting the torque at the time of initial opening of a cap of a synthetic resin container with a closed mouth part, when the cap is tightened on the cough mouth part, the mouth part comes into contact with a cap sealing material provided on the inner upper surface of the cap. A chamfer is provided at the inner corner of the opening end of the cap to adjust the torque when the cap is initially opened.

(Function) According to the above-described means, the area of the opening end can be arbitrarily set by providing a chamfered portion at the inner corner of the opening end of the mouth.

If this chamfer is made larger, the area of the opening end will be reduced, and when the cap is tightened to the opening, the compressive stress generated on the contact surface of the cap sealing material with the 11n opening end will increase in response to the compressive load from the opening end. be done. This makes it easier for the cap seal material to bite into the opening end, and as a result, the cap seal material also comes into contact with the chamfered portion, increasing its contact surface.

Therefore, as the chamfer increases in size, the torque when opening a closed cap increases due to the increase in frictional force as the contact surface increases.

In addition, if there is less chamfering, the compressive stress generated on the contact surface of the cap sealing material with the open end will not be increased so much, and the contact surface of the cap sealing material will not be increased, so the torque when opening the closed cap will be lower than the above. is smaller compared to the case of .

Therefore, depending on the size of the chamfered part on the opening end,
The magnitude of the cap opening torque is adjusted.

(Embodiment) An example of an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a PET container whose opening end has been chamfered on the inside using the method for adjusting the opening torque of a synthetic resin container according to the present invention.
This is the top of the bottle.

The SS P E T bottle is molded by biaxial stretching blowing, and the body 1 is formed into a substantially cylindrical shape, and the mouth 2 whose diameter decreases upward from the body 1 is connected to the other parts of the container. It is made thicker. A threaded part 4 is formed in the mouth part 2 all around the circumferential direction from the open end 3 to the lower outer side thereof, and a support ring 5 is provided at the lower part of the threaded part 4. The mouth part is closed by a synthetic resin cap 6, and the cap 6 has a threaded part 7 formed all around the inner circumferential direction thereof to be screwed into the threaded part 4 of the mouth part 2, and a threaded part 7 on the inner upper surface. A cap sealing material 8 is provided.

The open end 3 is provided with a chamfered portion 9 along the entire circumferential direction at the inner corner thereof, and when the chamfer angle is θ, the width of the open end 3 is W, and the width of the chamfered portion 9 is is formed in W2.

In the PET bottle constructed in this way, as shown in FIG. 2, the width WI of the open end 3 is reduced by being cut by the chamfered part 9, so that when the cap 6 is tightened on the mouth part 2, The contact surface of the cap seal material 8 with the open end 3 becomes smaller, and the compressive stress generated on the contact surface of the cap seal material 8 is increased due to the compressive load received from the open end 3.

As a result, the cap sealing material 8 bites deeply into the open end 3 and comes into contact with the chamfered portion 9, and as a result, when the cap 6 is completely closed, the contact surface increases to W, +W. .

As the contact surface w, +W increases, the frictional force when opening the cap increases, and as a result, a large torque is required to open the cap 6.

Therefore, the size of the chamfered portion 9 is adjusted such that the chamfer angle θ
By setting the width W2 and the width W2, the opening torque is increased.

From the above, by appropriately setting the size of the chamfered portion 9 on the open end 3 as the chamfer angle 62 width W2, the magnitude of the opening torque of the cap 6 can be adjusted to suit the purpose of the container. It can be set to .

In the above description, the cap 6 is made of synthetic resin, but caps made of other materials such as aluminum alloy are equally useful.

In addition, in order to adjust the size of the chamfered part 9 to be formed, when molding the preform by injection molding prior to biaxial stretch blow molding, the chamfered part 9 of the preform mold is adjusted. Either adjust the size of the chamfered portion 9 by replacing the part to be molded, or prepare a mold in advance so that a larger chamfered portion 9 is formed, and then modify the mold appropriately. This can be done by

(Effects of the Invention) As is clear from the above description, the present invention provides a chamfered portion at the inner corner of the open end of the mouth to adjust the contact area between the open end and the cap sealing material. You can adjust the torque when opening the cap that is closed in the section.
Adjustment of the opening torque for synthetic resin containers allows you to adjust the opening torque of synthetic resin containers by simply changing the opening end of the mouth, without having to perform time-consuming work such as adjusting the tightening torque on the cap itself. It has the effect of providing a method.

[Brief explanation of drawings]

1 and 2 show an example of the implementation of the present invention.
The figure is a cross-sectional view of the upper part of the synthetic resin container, and FIG. 2 is a cross-sectional view showing a state in which the mouth of the container is closed with a cap. 2... Mouth part 3... Opening end 4... Threaded part 6... Cap, cap sealing material, chamfered part

Claims (1)

[Claims] Method for adjusting torque at initial opening of a cap of a synthetic resin container in which a threaded portion is provided in the circumferential direction on the outside of the mouth, and a cap is screwed onto the mouth from the outside and tightened to close the mouth. In this method, a chamfer is provided at the inner corner of the opening end of the mouth portion that contacts the cap sealing material provided on the inner upper surface of the cap when the cap is tightened to the mouth portion, and the torque at the time of initial opening of the cap is reduced. A method for adjusting the opening torque of a synthetic resin container, the method comprising: adjusting the opening torque of a synthetic resin container.