JPH048304B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a synthetic resin container lid having pilfer-proof properties, and more specifically, a skirt wall having a circumferential weakening line extending in the circumferential direction and extending in the axial direction. The present invention relates to a method of manufacturing a synthetic resin container lid in which an axial weakening line is also formed.

<Prior Art> Recently, synthetic resin container lids have been proposed and put into practical use in place of metal container lids as container lids with pilfer-proof properties for containers such as food and beverage bottles. I'm getting used to it. A typical example of a prior art document disclosing such a synthetic resin container lid is JP-A-58-51116.

The synthetic resin container lid disclosed in JP-A-58-51116 has a top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall. A line of weakness is formed. This circumferential weakening line is composed of a plurality of slits (kerfs) extending in the circumferential direction at intervals in the circumferential direction and a plurality of bridge portions located between the slits. A female thread is formed in a region above the circumferential weakening line on the inner circumferential surface of the skirt wall, and an appropriate shape is formed in a region below the circumferential weakening line on the inner circumferential surface of the skirt wall. An engagement means is formed. The above-mentioned Japanese Patent Application Laid-Open No. 58-51116 discloses that a plurality of bridges are provided in order to allow the lid to be removed from the neck of the container without leaving a part of the lid on the neck when the container is opened. At least one of the bridging parts is made to be a non-breakable bridging part that is stronger than the other bridging parts and does not break when opening the mouth and neck part, and in relation to the non-breakable bridging part, in the axial direction. Forming an extending axial line of weakness is also disclosed.

Furthermore, the above-mentioned Japanese Patent Application Publication No. 58-51116 also discloses a method for manufacturing the synthetic resin container lid of the above-mentioned type. In this manufacturing method, a preformed body is formed that includes a top wall and a skirt wall that hangs down from the periphery of the top wall. A female thread is formed in the upper region of the inner peripheral surface of the skirt wall of this preformed body, and an engagement means is formed in the lower region. Furthermore, a plurality of protrusions are formed at intervals in the circumferential direction in a region between the female thread and the engagement means on the inner circumferential surface of the skirt wall. Following the shaping of the preform, the skirt wall is continuously cut in the circumferential direction from the outside in the area where the protrusions are present at a cutting depth such that only the protrusions remain. When such cutting is performed, the skirt wall is completely cut off at the angular portion where the protrusion does not exist, forming a slit, and the protrusion that remains without being completely cut constitutes a bridge portion. When at least one of the bridges is made to be an unbreakable bridge, the above-mentioned cutting is not carried out at a particular angular position, and the strength of the bridge existing at such an angular position is made greater than that of other bridges. do. The formation of the axial line of weakening is accomplished by partially cutting the skirt wall in the axial direction at the desired location after the circumferential cutting described above.

<Problems to be Solved by the Invention> The manufacturing method disclosed in the above-mentioned Japanese Unexamined Patent Publication No. 58-51116 has the following problems to be solved. That is, when forming the axial direction weakening line, the axial direction weakening line is located at a specific position with respect to the non-breakable bridge portion (a position that coincides with or is close to one circumferential end of the non-breakable bridge portion). is necessary. Therefore, when performing an axial cut to form an axial line of weakness, it is necessary to position the preform at a specific angular position with sufficient precision relative to the cutting blade. However, because the outer circumferential surface of the preformed body is usually uniform over the entire circumferential direction, it is not impossible to automatically position the preformed body at a specific angle position quickly and precisely. It is also extremely difficult to automate and speed up manufacturing.

The present invention has been made in view of the above facts, and its technical problem is that automation and speeding up can be realized easily enough without the need to position the preformed body at a specific angular position. An object of the present invention is to provide a method for manufacturing a synthetic resin container lid that also has an axial weakening line.

<Means for Solving the Problems> The solution means of the present invention for achieving the above-mentioned technical problems is that, in molding a preformed body, at least one of the plurality of protrusions has a circumferential width other than that of the preformed body. The purpose is to form a wide protrusion that is larger than the circumferential width of the protrusion, and to form an axially weakened line that extends in the axial direction by being positioned in a predetermined relationship with the wide protrusion.

That is, according to the present invention, there is provided a top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall, and the inner peripheral surface of the skirt wall has a female thread and a region where the female thread exists. A pre-molded body having a plurality of protrusions arranged at intervals in the circumferential direction on the lower side and an engaging means arranged below the area where the protrusions are present is made of synthetic resin. The material is molded, and then, in the region of the skirt wall of the preformed body where the protrusion exists, the skirt wall is circumferentially cut at a cutting depth such that only the protrusion remains from the outer circumferential surface of the skirt wall. In a method for manufacturing a synthetic resin container lid, which involves cutting continuously over a period of time, at least one of the plurality of protrusions formed on the inner peripheral surface of the skirt wall of the preformed body The skirt wall of the preformed body is further provided with a wide protrusion whose direction width is larger than the circumferential width of the other protrusions, and which is located in a predetermined relationship with respect to the wide protrusion, and at least A manufacturing method is provided, characterized in that an axial weakened line is formed that extends axially through a region where the engagement means is formed.

<Function> In the manufacturing method of the present invention, since the axial weakening line is formed in the molding of the preformed body,
There is no need to subsequently perform an axial cutting step to form an axial line of weakening in the preform, thus avoiding the above-mentioned problems associated with performing such an axial cutting step. The formation of the axial weakened line in the preformed body does not cause so-called forced cutting during die cutting because the axial weakened line extends in the axial direction, that is, in the die cutting direction, and therefore, the axial weakened line does not cause breakage, etc. This can be carried out suitably without causing any problems. If a circumferential weakening line is also to be formed in the preformed body, excessive punching will occur due to the presence of the axially extending slits, resulting in problems such as fracture of the bridge. In the manufacturing method of the present invention, the circumferential weakened line is formed by performing circumferential cutting subsequent to the shaping of the preform. Since this circumferential cutting is carried out continuously in the circumferential direction, it can be carried out sufficiently easily and quickly.
The normal ridges constitute a normal bridge, and the wide ridges constitute a wide bridge, ie, a non-breakable bridge.

<Preferred Specific Example of the Invention> Hereinafter, a specific example of the manufacturing method according to the present invention will be described in more detail with reference to the accompanying drawings.

In one specific example of the manufacturing method according to the present invention,
First, a preform 2 having the form shown in FIG. 1 is molded from a suitable synthetic resin material such as polypropylene or polyethylene. Molding of such a preform 2 can be carried out by injection or compression molding, which is known per se.

The preformed body 2 has a circular top wall 4 and this top wall 4.
A cylindrical skirt wall 6 that hangs down from the periphery of the cylindrical skirt wall 6 is provided. In the illustrated example, an annular protrusion 8 is formed on the inner surface of the top wall 4. A step 10 displaced radially inward is formed near the lower end of the outer surface of the skirt wall 6, and a step 12 displaced radially outward is formed near the lower end of the inner surface of the skirt wall 6. and 14 are formed, and the skirt wall 6
The thickness is gradually reduced downward in the axial direction from the step portions 10, 12, and 14 as boundaries. The step 1 on the outer surface of the skirt wall 6
In the region above 0, an uneven or knurled shape 16 is formed to prevent fingers engaged therefrom from slipping. On the other hand, the skirt wall 6
In the region 18 located relatively upward on the inner surface of the
A female thread 20 is formed. A region 22 of the inner surface of the skirt wall 6 located below the region 18 (i.e., a region between the step portion 12 and the step portion 14)
A plurality of (14 in the illustrated case) protrusions 24 are formed at intervals in the circumferential direction. Conveniently, each of the plurality of ridges 24 extends substantially parallel to the central axis 26, such that each of the plurality of ridges 24 extends radially inwardly from the inner surface of the skirt wall 6. Advantageously, the amount of protrusion is substantially the same as the radial depth of the step 12. A region located below the region 22 on the inner surface of the skirt wall 6 (i.e., a region below the step portion 14) 2
At 8, an engaging means 30 is formed. In the illustrated embodiment, the engagement means 30 is comprised of a plurality of generally triangular flap pieces extending radially inward from the inner surface of the skirt wall 6 at circumferentially spaced intervals. If desired, from a plurality of flap pieces having other suitable shapes, from a plurality of protrusions having suitable shapes arranged at intervals in the circumferential direction, or (from the axial weakening line portion described later). The engaging means 30 can also be constituted by an annular protrusion extending continuously in the circumferential direction.

To explain with reference to FIG. 2 together with FIG. 1, in the manufacturing method according to the present invention, the preformed body 2
It is important that at least one of the plurality of protrusions 24 formed in the above-mentioned protrusions 24 is made into a wide protrusion 24A whose circumferential width is larger than the circumferential width of the other protrusions 24. . In the illustrated case, one of the 14 protrusions 24 is made into a wide protrusion 24A. Additionally, it is important that at least the area 28 of the skirt wall 6 is formed with an axial line of weakening 32 extending in the axial direction and positioned in a predetermined relationship with respect to the wide ridge 24A. In the illustrated embodiment, the axial line of weakness 32 extends along the central axis 26 from an upper end located slightly above said area 28 (i.e., an upper end located within the lower part of said area 22) to a lower end of the skirt wall 6. It extends substantially parallel to the If desired, the axial line of weakening 32 can extend along the central axis 2
It can also be tilted relative to 6. The axial weakening line 32 is in a predetermined relationship with the wide protrusion 24A, that is, one end in the circumferential direction of the wide protrusion 24A, preferably in the direction of rotation of the container lid when the container lid is attached to the mouth and neck as will be described later. It is important that it is located substantially in line with or in close proximity to the front end, as viewed from above (clockwise in FIG. 1). Regarding the plurality of flap pieces (or protrusions) constituting the engagement means 30, the axial weakening line 32 is located between two adjacent flap pieces (or protrusions).
It is convenient to be located in between. The axial weakening line 32 itself can consist of a so-called score, which is produced by locally reducing the thickness of the material. Alternatively, the axial weakening line 32 can also be formed from a so-called perforation.
In the illustrated embodiment, there is only one wide protrusion 24A, but if desired, two or more circumferentially spaced protrusions 24 may be added to the wide protrusion 24A.
It is also possible to form an axial weakened line 32 in association with each of the wide protrusions 24A.

In one specific example of the manufacturing method according to the present invention,
After the preformed body 2 is formed, the circumferential weakening line is formed. Referring to FIG. 3, the circumferential weakening line is formed by the cutter 34 in the region 22 (i.e., the region 22 where a plurality of protrusions 24 are present) in the skirt wall 6 of the preformed body 2. This can be accomplished by cutting circumferentially at a predetermined depth from its outer surface. In the illustrated example, the disc-shaped cutter 34 is rotated at a relatively high speed about its central axis, and the preformed body 2 is rotated about its central axis or along the outer periphery of the preformed body 2. By moving the disc-shaped cutter 34,
The entire circumference of the preformed body 2 is exposed to the action of the disc-shaped cutter 34. It is important that the cutting depth of the cutter 34 is such that the skirt wall 6 is cut in the region 22 while leaving only the plurality of protrusions 24 formed on the inner surface of the skirt wall 6.

By cutting as described above, a circumferential weakened line 36 (see FIG. 4) is formed in the region of the skirt wall 6. In such a circumferential weakened line 36, only the portion where the plurality of protrusions 24 are present remains, and this remaining portion defines the bridge portion 38. Between the bridges, the skirt walls 6 are completely separated.
Thus, the skirt wall 6 has a circumferential weakening line 3
The pilfer-proof hem 42 is divided into a main portion 40 located above the circumferential weakening line 36 and a pilfer-proof hem 42 located below the circumferential weakening line 36. 40. The upper end of the axial direction weakening line 32 mentioned above intersects with a portion of the circumferential direction weakening line 36 other than the bridge portion 38 (i.e., the slit), or the above-mentioned axial direction weakening line 32
The upper end of the bridge portion 3 is located at the circumferential weakening line 36
It is convenient to match the portion other than 8 (ie, the slit).

As described above, at least one of the plurality of protrusions 24 in the preformed body 2 is the wide protrusion 24A, and therefore, when the circumferential direction weakening line 36 is formed as described above, the circumferential direction Weakening line 3
Of the plurality of bridging parts 38 in No. 6, the bridging part 38A generated due to the wide protrusion 24A inevitably becomes the wide bridging part 38A. On the other hand, as described above, in the preformed body 2, the wide protrusion 24A and the axial direction weakening line 32 are positioned in a predetermined relationship. Thus, the wide bridging portion 38A in the circumferential weakened line 36 and the axial weakened line 32 are necessarily located in a predetermined relationship without requiring any special association operation etc. when forming the circumferential weakened line 36. It turns out.

To explain with reference to FIG. 4, after or before the formation of the circumferential weakening line 36 described above, a line is formed on the inner surface of the top wall 4 of the preformed body 2, more specifically, on the inner surface of the top wall 4. A sealing liner 44 made of a suitable synthetic resin material can be formed within the annular ridge 8. Formation of the sealing liner 44 can be accomplished, for example, by stamping methods that are well known per se. Instead of forming the sealing liner 44 separately, the top wall 4 of the preform 2
A sealing protrusion of an appropriate form can also be integrally formed on the inner surface of the holder.

The synthetic resin container lid 46 manufactured as described above has a neck portion 4 having a shape as shown in FIG.
Applicable to containers comprising 8. A male thread 50 and a locking jaw portion 52 located below the male thread 50 are formed on the cylindrical outer peripheral surface of the mouth and neck portion 48 .

When closing the mouth and neck part 48 with the container lid 46, the container lid 46 is fitted onto the mouth and neck part 48, and the container lid 46 is rotated in the closing direction, that is, clockwise when viewed from above in FIG. In this way, the female thread 20 of the container lid 46 is screwed into the male thread 50 of the neck portion 48. Thus, the container lid 46 moves downward in the axial direction as it rotates, and when the female thread 20 is fully screwed into the male thread 50, the engaging means 30 of the container lid 46 engages with the locking jaws of the neck portion 48. 52 and is locked onto the lower surface of the locking jaw portion 52. Also, the sealing liner 44 of the container lid 46 is pressed against the top surface of the neck 48, thus sealing the neck 48.

In order to unseal the neck portion 48, the container lid 46 is rotated in the opening direction, that is, counterclockwise when viewed from above in FIG. In this way, since the female thread 20 of the container lid 46 is moved along the male thread 50 of the neck portion 48, the container lid 46 moves upward in the axial direction as it rotates. However, since the engaging means 30 formed on the inner surface of the pilfer-proof hem 42 of the container lid 46 engages with the lower surface of the locking jaw 52 of the neck part 48, cannot move and therefore the circumferential line of weakness 36, more particularly its bridging portion 38.
, and the axial line of weakness 32 . Thus, the circumferential weakening line 3
The bridging portion 38 at 6 is broken leaving the wide bridging portion 38A which is wide and therefore strong, and the axial weakening line 32 is also broken, thereby making the pilfer-proof hem 42 into a band-like shape. When opened, the engagement means 30 is disengaged from the lower surface of the locking jaw 52. After that,
The entire container lid 46, including the pilfer-proof skirt 42, which is connected to the main portion 40 by the wide bridge 38A, which remains unbroken, is moved axially upwards with rotation, thus The entire container lid 46 is removed from the neck part 48, and the neck part 48 is opened.

Although a specific example of the manufacturing method of the present invention has been described above in relation to a specific form of container lid with reference to the accompanying drawings, the present invention is not limited to such specific example, and the scope of the present invention is Needless to say, various modifications and modifications are possible without departing from the above.

<Effects> According to the manufacturing method of the present invention, there is no need to position the preformed body at a specific angle position after the molding of the preformed body, and therefore, it is possible to manufacture a synthetic resin container lid that also has an axial weakening line. , can be automated and speeded up quite easily.

[Brief explanation of drawings]

FIG. 1 is a side view, partially in cross section, of an example of a preformed body molded in the first stage of the manufacturing method of the present invention. FIG. 2 is a partially exploded view showing a part of the preformed body shown in FIG. 1 on an enlarged scale. FIG. 3 is an enlarged partial sectional view showing an example of a method for forming circumferential weakening lines on the preformed body of FIG. 1 at a later stage of the manufacturing method of the present invention.
FIG. 4 shows a state in which an example of a container lid manufactured by the manufacturing method of the present invention is attached to the mouth and neck of the container.
FIG. 3 is a side view partially cut away and partially cut away. 2...Preformed body, 4...Top wall, 6...Skirt wall, 20...Female thread, 24...Protrusion, 24A...
... Wide protrusion, 30 ... Engagement means, 32 ... Shaft direction weakening line, 36 ... Circumferential direction weakening line, 38
...Bridging portion, 38A... Wide bridging portion, 40... Main part of skirt wall, 42... Pilfer-proof hem, 46... Container lid, 48... Mouth and neck, 50...
Male thread, 52...locking jaw part.

Claims (1)

[Scope of Claims] 1 Comprising a top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall, the skirt wall has a female thread on the inner circumferential surface, and a region below the area where the female thread exists. A pre-molded body having a plurality of protrusions arranged at intervals in the circumferential direction and an engaging means arranged below the area where the protrusions exist is made of synthetic resin material. Then, in the area where the protrusion of the skirt wall of the pre-formed body exists, the skirt wall is cut from the outer peripheral surface of the skirt wall to a depth such that only the protrusion remains. In a method for manufacturing a synthetic resin container lid, which involves continuous cutting across the entire length; The wide protrusion has a width larger than the circumferential width of the other protrusions, and the skirt wall of the preformed body is further provided with at least the engagement member positioned in a predetermined relationship with respect to the wide protrusion. A manufacturing method characterized in that an axial weakened line is formed that extends in the axial direction in a region where the joining means is formed.