JP2004514610A - Screw structure for lid structure - Google Patents

Abstract

A lid structure including a container neck (24) having an external thread (34) engaged with an internal thread (58) of the container neck (24). The external thread (34) includes a pad (44) on the bottom screw convolution (36). The sealing member (64) of the lid body (30) is drawn downward against the sealing surface (70) of the container neck (24).

Description

[0001]
(Technical field)
The present invention relates to a screw structure for a lid structure, for example a screw structure used between two members in a multi-piece lid or between a container neck and a lid. In particular, the present invention relates to a screw structure adapted to hermetically seal between the lid members or between the lid and the container neck.
[0002]
(Background of the Invention and Technical Problems Shown in the Prior Art)
A common type of container has a threaded neck adapted to engage a threaded lid (screw lid). Typically, the screw cap is formed of a cap body having threads that engage the threaded neck of the container. The lid body includes a spout such as an end wall with a spout opening. A closure for closing the opening when in the closed state with respect to the lid body can be provided. Typically, such a lid is attached to the container neck by an automatic lid mounting machine.
[0003]
In containers using screw caps where the container and / or the lid, or both, are formed of an elastic plastic material, it is difficult to keep the lid sealed to the container neck under certain circumstances. The lid may loosen or slightly move axially on the container neck. This is known as "chucking". Elastic thermoplastics produce a cold flow (resin creep phenomenon) under pressure, which results in a gradual loosening of the lid on the container neck. The low coefficient of friction between the screw on the lid and the screw on the neck also increases the tendency of the lid to loosen gradually, ie the screws are slightly loosened. Conventional screw caps can cause some unscrewing or loosening from the threaded container neck when shipped and / or subjected to rough handling.
[0004]
Known lid retaining structures include the structure disclosed in U.S. Pat. No. 3,682,345, in which the container screw frictionally locks the cap screw to the container neck screw to hold the lid sealed against the container neck. A projection for engagement is included on each screw turn.
[0005]
A container screw structure with a projection on each screw turn increases the rotational force required to loosen the lid from the container neck, but for the same reason, the lid is first screwed into the threaded neck with an automatic lid mounting machine. The required rotational force also increases considerably. This increased rotational force exists throughout the rotational engagement of the lid with the threaded neck and also increases the energy consumption of the lidder.
[0006]
The inventor of the present application has found that the rotational force required for screwing the lid can be minimized in a wide range, while the lid and the container structure can keep the lid airtightly sealed against the container neck. Has been found to be advantageous. The inventor has found that undesired undesired axial orientation with respect to the container neck due to excessive clearance between the lid and the container neck, or due to loosening of the screw such that the lid is partially disengaged from the container neck. It has been recognized that it would be advantageous to provide a lid and container structure that prevents lid movement.
[0007]
A first and a second lid member screwed together, wherein a preselected screw engagement between the members closely contacts the sealing surface of the first member to the sealing surface of the second member; Lid structures adapted to be made are also known. For example, the first member is a lid main body, and the second member is a lid pouring and closing stopper screwed to the lid main body. The lid body is sealed to the container and has a penetrating outlet passage and an upright valve member. The closure has a spout opening, which is closed by the valve member when the closure is relatively rotated (screwed) over the lid body to the sealed position. Such a lid structure can use a preselected relative rotational position between the members as the seal position. The preselected relative rotational position can be determined, for example, by one or more rotational stops located on one or both members. In this preselected relative rotational position, both parts must simultaneously be in a preselected threaded position to ensure a sufficient sealing action. It was doubtful that this relationship was actually being implemented.
[0008]
The inventor of the present application believes that the sealing action between the two lid members depends on the screw tolerance, the axial gap of the screw, and the like, and the effective sealing action at a preselected relative rotational position between the lid members is further improved. It has been recognized that it would be desirable to provide a threaded structure that is assured by:
[0009]
The present inventor has recognized that it would be advantageous to provide an improved screw structure for a lid structure that has reduced ease of loosening of the lid during shipping, storage and handling.
[0010]
(Brief summary of the invention)
SUMMARY OF THE INVENTION The present invention is a screw structure for a lid structure disposed between two lid members, which, once fully engaged, exerts an effective axial sealing force between the two members. It also provides a threaded structure that mitigates external forces, internal pressure of the content product, or material, and / or prevents subsequent loosening of the member caused by cold flow of one or both elastic plastic materials. The two lid "members" can be two cooperating parts of a multi-piece lid assembly attached to the container, or the two members can be a container neck and a lid member.
[0011]
According to one aspect of the invention, the two threaded lid members are adapted to be sealed to one another around the opening at a preselected relative rotational position, wherein one or more pads are connected to one another. One screw-turn portion of the thread of one member is provided such that when a preselected relative rotational position is reached, one screw-turn portion of the other member exceeds the pad. During the last few degrees (angle) of screwing of the two members when reaching a preselected relative rotational position, the threaded portion of the other member exceeds one or more pads and the height of the pads The lid members are drawn toward each other by a distance equal to, exerting a suitable axial sealing force between the two members. If the resilient sealing member is disposed between the two members, the sealing member is compressed by the axial sealing force to seal the members together.
[0012]
Another concept of the present invention provides a cooperating threaded structure for engaging a lid body with a threaded neck of a container. The screw structure of the present invention includes a first helical screw formed on the outer surface of the container neck, and a second helical screw formed on the inner surface of the lid body and cooperating with the first helical screw. The first and second helical screws can be continuous or interrupted. The first helical screw includes one or more pads disposed on one screw convolution of the helical screw. The second helical thread is configured to relatively loosely engage the first helical outer thread of the container neck until the first pad is reached. These pads formed on the first helical screw of the container neck have a downwardly projecting thickness, the thickness being the axial play between the screw-turned parts of the two helical screws in the screw structure. It is chosen to fill a substantial amount of the gap. Thus, the present invention reduces the vertical gap or play between the screw on the lid and the screw on the container while minimizing the rotational force required to attach the lid body to the container neck.
[0013]
These pads pull the lid body downwardly over the container neck to seal against the container neck. These pads may be of a preselected height to compress a resilient seal member held in the lid body in contact with the container neck by a preselected amount.
[0014]
According to one embodiment of the invention, these pads are substantially rectangular in shape with angled end faces. The pad is formed integrally with the first helical screw of the container neck and protrudes below its lowest screw convolution.
[0015]
If the container neck is formed as part of a bottle or other container, the invention can be realized inexpensively by adjusting the bottle tool. No additional material is required to form an extrusion blow molded bottle with one or more pads on the screw, and a minimum amount of material is needed to form an injection blow molded bottle with one or more pads on the screw It is said.
[0016]
While gradual embodiments include one or more pads on the container neck, the present invention alternatively includes forming one or more pads on the lid body. In such an embodiment, the pads are placed on top of the lid body screws so that the lid body can be screwed almost completely onto the container neck with minimal rotational force until the container screws reach the pads. Are arranged so as to protrude upward from the screw-turned portion.
[0017]
Many other advantages and features of the present invention will be readily apparent from the following detailed description of the invention and its embodiments, the claims, and the accompanying drawings.
[0018]
BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings form a part of the specification, and like reference numerals are used to refer to like parts throughout.
[0019]
(Detailed description of preferred embodiments)
While the present invention may take many different forms, some specific examples of which are illustrated in the drawings and described herein in detail, the disclosure herein is a basic description of the invention. It should be regarded as illustrative and not intended to limit the invention to the particular embodiments illustrated.
[0020]
FIG. 1 shows a lid structure 20 including two lid members, a container neck 24 and a lid body 30. The container neck 24 can be formed of a suitable material such as glass or plastic. Advantageously, the lid body 30 is made of plastic. The container neck 24 has a plurality of screw turns including a bottom screw turn 36 and a top screw turn 38, which can be recognized by observing the contour of the screw structure. . The helical thread structure 34 can be a continuous thread or a discontinuous thread. The threaded structure 34 includes one or more pads 44 (only one shown) projecting downwardly from the bottom threaded portion 36. If multiple pads are used, the pads can be spaced around the centrifuge of the threaded structure. Each pad 44 includes an angled or inclined front end surface 44a, an inclined bottom surface 44b, and an angled rear end surface 44c.
[0021]
Lid body 30 includes a deck 46 and a depending skirt 48. The deck 46 includes a discharge nozzle 50. The depending skirt 48 includes an inner helical thread structure 58 that can be rotationally threaded with the thread structure 34 of the container neck 24. The screw structure 58 includes a plurality of screw turns, including a top screw turn 60, an intermediate screw turn 62, and a bottom screw turn 63, which are formed by viewing the lid body in cross-section. I can recognize. A “crab claw” seal 64 or other strut compression seal is provided on the inner surface of the deck 46. The seal 64 is compressed by the upper sealing surface 70 of the container neck 24 when the lid body 30 is screwed onto the container neck 24 to form a seal.
[0022]
FIG. 2 shows the threaded structures 34, 58 a few degrees (angle) before the last tightening. The seal 64 has not yet been completely deformed or compressed by the upper sealing surface 70. The bottom threaded portion 63 of the lid body 30 has not yet encountered the pad 44 (located out of the plane of FIG. 2 and thus cannot be seen in FIG. 2). There is a vertical gap, i.e., play a, between the intermediate screw turning portion 62 of the lid body and the lowest and highest screw turning portions 36, 38 of the container neck 24. A vertical gap a also exists between the uppermost threaded portion 38 of the container neck 24 and the uppermost and intermediate threaded portions 60, 62 of the lid body 30.
[0023]
Until the bottom screw convolution 63 of the lid body reaches the pad 44 (FIG. 3), the gap a (FIG. 2) between the screw convolutions 60, 62, 63 of the lid body and the screw convolutions 36, 38 of the container neck is It is sufficient to provide a relatively loose screwing, which reduces the rotational force and allows a fast and trouble-free screwing of the lid body 30 to the container neck 24.
[0024]
FIG. 3 shows the lid body 30 fully tightened on the container neck 24, whereby the seal 64 is elastically compressed against the upper sealing surface 70 of the container neck 24. In this state, the bottom screw turning portion 63 is pulled downward below the pad 44. The pad 44 has an axial length, that is, a height b. As the bottom screw convolution 63 is pulled down a distance b, the axial play a (FIG. 2) between the threaded structures 34, 58 is also reduced by the length b. This reduction is important and prevents the container neck 24 from chucking from the lid body 30. In one currently preferred embodiment, this distance b is about 0.508 mm (0.020 inch). In any case, the engagement between the pad 44 and the screw of the lid skirt preferably does not take place until almost the last of the threading for mounting has been reached. Thus, the increased rotational force required to engage the pad and move the lid to the final threaded position is not required in almost every threading step.
[0025]
The location of pad 44 can also be used for venting or bleeding the pressure vessel. When the lid is first unscrewed, the screw on the lid is quickly released from the pad, resulting in a loose fit along the screw due to pressurized gas (eg, carbon dioxide from a carbonated beverage bottle). Will function as a passage for bleeding air.
[0026]
Pads 44 are generally shown as rectangular, but other shapes are possible, including semicircular, triangular, tapered, and the like. Also, the number of turns of the screw of the container and the number of turns of the screw in the lid body can be less or more than in the illustrated example without departing from the invention.
[0027]
From the foregoing, it will be appreciated that many modifications and variations can be made without departing from the spirit and scope of the invention. It is to be understood that no limitations on, or should be intended to, the particular devices set forth herein. It is, of course, intended that all modifications that come within the scope of such claims be covered by the dependent claims.
[Brief description of the drawings]
FIG.
FIG. 4 is a cutaway elevational view of the container neck and the lid body of the present invention.
FIG. 2
FIG. 4 is an enlarged cutaway sectional view of the container neck and the lid body of the present invention at a relative position where the lid body is partially screwed into the container neck.
FIG. 3
FIG. 3 is a cross-sectional view similar to FIG. 2, but showing the container neck and the lid body in a relative position where the lid body is completely screwed into the container neck of the present invention.

Claims (6)

A screw structure for engaging the first lid member with the second lid member,
A first lid member having a first sealing surface;
A second lid member having a second sealing surface;
A first screw structure formed on an outer surface of the first lid member and including a plurality of screw turning portions;
A second screw structure formed on the inner surface of the second lid member and including a plurality of screw turns.
One of the first threaded structure and the second threaded structure includes a pad extending axially from one of the plurality of threaded portions of the threaded structure, the one of the plurality of threaded portions in the threaded structure; The one convoluted portion of the screw structure is a final screw convoluted portion that engages the other of the first and second screw structures in the direction of screwing the second lid member to the first lid member. Wherein the pad is adapted to be screwed over the other threaded structure of the first and second threaded structures, and wherein the first sealing surface is resiliently connected to the second sealing surface. A screw structure in which the pad has a sufficient height to axially pull the second lid member on the first lid member for pressing. The first threaded structure includes a first bottom screw convoluted portion, the second threaded structure includes a second bottom screw convoluted portion, and the pad includes the first bottom screw of the first threaded structure. A second threaded portion formed in a convoluted portion, wherein the second bottom screw convoluted portion of the second threaded structure is screwed over the pad to draw the second sealing surface toward the first sealing surface. 2. The threaded structure of claim 1, wherein the pad includes a front end surface that is inclined in a tangential direction of the thread. The screw structure according to claim 1, wherein the first lid member includes a lid body, and the second lid member includes a container neck. 4. The screw structure according to claim 3, wherein the second lid member includes a pouring opening. The one screw turning portion is a first bottom screw turning portion of the plurality of screw turning portions of the first screw structure, and the second screw turning portion is a second screw turning portion of the plurality of screw turning portions. And wherein the first threaded structure is loosely threaded with the second threaded structure until the second bottom threaded portion of the second lid member exceeds the pad. The screw structure according to claim 1, wherein the screw structure is configured to fit. The one screw structure is the first screw structure, the second lid member includes an elastic seal member, and the second seal surface is supported by the elastic seal member, and the second cover member includes an elastic seal member. The second screw of the second lid member is arranged to be in contact with the first sealing surface of the first lid member when the lid member is drawn to the first lid member. The container lid structure according to claim 1, wherein the pad has a height sufficient to elastically compress the seal member when the structure exceeds the pad.