JPH0627594U - Synthetic resin cap - Google Patents

Abstract

(57) [Summary] [Structure] On the inner surface of the PP ring, a plurality of plate-shaped wings are located closer to the tip in the cap rotation direction at the time of opening and toward the inside of the cap, and the base end thereof is gradually downward. In the cap made of synthetic resin provided on the downstream side in the cap opening direction, the PP ring is provided with an inclination score substantially parallel to the base end of the wing. [Effect] When a score is formed on the PP ring, the probability that the inclined score overlaps the wing is reduced, and the incidence of defective score formation can be significantly reduced. When the cap is opened, the score breaking force acts almost at right angles to this tilt score, so it is more susceptible to score breaking force than the conventional vertical score, preventing score failure. You will definitely be able to break the score.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a so-called wing lock cap, which is a synthetic resin cap provided with a wing for engaging with a step portion of a bottle mouth on the inner surface of a pill fur proof ring.

[0002]

[Prior art]

 FIG. 5 shows a wing lock cap disclosed in JP-A-58-51116. This cap is roughly configured by a disc-shaped top plate portion 1 and a skirt portion 2 hanging down from the peripheral edge thereof. A liner 16 is attached to the inner surface of the top plate portion 1. A screw 9 is formed on the inner surface of the middle part of the skirt portion 2 so as to be screwed with the screw of the mouth of the bottle to which the cap is attached. On the inner surface of the lower portion of the skirt portion 2, bridge forming ribs 3 ... The bridge forming ribs 3 are formed in the shape of a rod having a substantially square horizontal cross section, and are projectingly provided on the inner surface of the skirt portion 2 so that the longitudinal direction thereof is along the longitudinal direction. A notch 12 is formed along the circumferential direction in the protruding portion of the bridge forming ribs 3 in the skirt portion 2 of the cap. The skirt portion 2 is divided into a cylindrical portion 2a on the top plate portion 1 side and a pilfer proof ring portion (hereinafter referred to as a PP ring) 2b on the lower end side by the notch 12. A cap body 20 is formed from the top plate 1 and the cylinder 2a. The cap body 20 and the PP ring 2b are connected to each other only by the bridge forming rib (hereinafter referred to as rib) 3. A plurality of wings 10 are projected on the inner surface of the PP ring 2b. These wings 10 have a substantially triangular plate shape, and are provided such that the tips thereof are located in the cap rotation direction A when the cap is opened and inside the cap. Further, the base ends of these wings 10 are provided so as to gradually incline toward the downstream side in the opening direction A toward the lower side.

This cap is used by being attached to the bottle mouth. When this cap is turned in the direction to attach it to the bottle mouth, when the wing 10 of the PP ring 2b hits the bottle mouth step, a force is applied to push the wing 10 in the rotation direction A when opening the cap. The tip of the wing 10 is displaced outwardly by further tilting depending on the direction (hereinafter referred to as a tilted state when mounted). As a result, the PP ring 2b can ride over the step of the bottle mouth with almost no resistance. When the wing 10 gets over the step of the bottle mouth, the wing 10 stands up to its original state and its tip is displaced inward, so that the wing 10 is locked under the step of the bottle mouth. When the cap is turned in the opening direction A to open the bottle, a force to erect the wing 10 is applied, so that the tip of the wing 10 tends to be displaced inward, and the wing 10 and the bottle mouth step portion Since the engaged state is strongly maintained, the PP ring 2b cannot climb over the stepped portion of the bottle mouth. On the other hand, since the cap body 20 rises, the bridge forming rib 3 is cut, the PP ring 2b remains in the bottle mouth, and only the cap body 20 is removed from the bottle mouth. Then, this indicates that the bottle has been opened.

FIG. 6 also shows a PP core 2b of such a wing lock cap having a vertical score (hereinafter, a vertical score) for separating the PP ring 2b separated from the cylindrical portion 2a from the container in a band shape. The cap disclosed in Japanese Patent Publication No. 63-11224 is shown as an example of the formation of the above. In this cap, two vertical scores 14a, 14b are formed on the PP ring 2b, the PP ring 2b and the cylindrical portion 2a are separated when the cap is opened, and the vertical scores 14a, 14b are broken, resulting in a PP ring. 2b can be removed from the mouth of the bottle in the shape of a band.

[0005]

[Problems to be solved by the device]

 These conventional wing lock caps have the following problems. In the former cap shown in FIG. 5, when the cap ring 2b and the cap body 2a are separated by turning the cap in the opening direction and the cap body 2a is removed from the bottle mouth, the separated PP ring 2b Since it remains in the mouth, it is troublesome to remove the PP ring 2b remaining in the bottle mouth when the bottle is collected and reused. Further, when the cap body 2a is closed again after being opened once, the PP ring 2b and the cap body 2a come into close contact with each other, and it is difficult to determine whether or not the cap is opened at a glance.

On the other hand, in the latter cap in which the vertical scores 14a and 14b are formed on the PP ring, the PP ring 2b is cut into a band shape and removed from the bottle mouth portion when the cap is opened as described above. Although the above-mentioned problem in the cap that leaves the ring 2b can be solved, in the cap in which the base end of the wing 10 is gradually inclined downward toward the downstream side in the opening direction A, two vertical scores are obtained. When forming 14a and 14b, there was a problem that the rate of poor score formation was high and the success rate of score breakage was poor. That is, when an attempt is made to form a vertical score on the PP ring 2b which is provided so that the base end of the wing 10 is gradually inclined downward in the opening direction A, the score crosses the wing. Since there is an interference convex part (bead) between the wings to prevent reversal tilting of the wing in the middle, the range in which the score can be formed is further narrowed. The probability that a score could be formed without hitting a wing or an interference protrusion was low. Furthermore, when the cap is opened, each force of the opening direction force (F1) and the ascending direction force (F2) acts on this score as shown in FIG. The force that breaks the score is the resultant force (F) of both of them, and the score breaking force (that is, the resultant force F) acts diagonally upward on the vertical score 14. Therefore, when the score 14 perpendicular to the PP ring 2b is formed, it becomes difficult for the score breaking force to directly act on the score, and the score 14 is hard to break. If the score 14 is easily cut, the score may be unnecessarily cut except when the cap is opened.

The present invention has been made in view of the above circumstances. It is possible to form a score on the PP ring of the wing lock cap and to remove the PP ring in a band shape when the cap is opened. The aim is to provide a cap that reliably forms a score without covering the part and that the score will surely break when the cap is opened.

[0008]

[Means for Solving the Problems]

 The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is a pilfer that is connected to a top plate portion, a tubular portion that hangs from the peripheral edge thereof, and a lower end of the tubular portion through a bridge. A proof ring is formed on the inner surface of the tube, and a screw that engages with the screw of the bottle mouth is formed on the inner surface of the pill fur proof ring. Direction and inside the cap, and the base end of which is provided so as to gradually incline downward toward the downstream side in the cap opening direction, in the synthetic resin cap, the pill fur proof ring comprises: It is a synthetic resin cap provided with an inclination score substantially parallel to the base end of the wing.

Further, the invention according to claim 2 comprises a top plate portion, a tubular portion hanging from a peripheral edge thereof, and a pill fur proof ring connected to a lower end of the tubular portion via a bridge. A screw is formed on the inner surface of the tubular portion that is screwed into the screw of the bottle mouth, and a plurality of plate-shaped wings are formed on the inner surface of the pill fur proof ring toward the tip in the cap rotation direction when the cap is opened and inward of the cap. Of the synthetic resin cap, which is located at the point where the base end of the cap gradually inclines toward the downstream side in the cap opening direction, near the place where the wings are connected, An interference protrusion is provided at a position opposite to the direction of rotation of the cap when the cap is opened, and two tilt scores almost parallel to the base end of the wing are added to the pill fur proof ring using the formula (n + 1) ( p1 + p2) -np2- > D> n (p1 + p2) + t (where p1 is the pitch between the wings, p2 is the distance between the wings and the interference projection, t is the width of the wings, and n is the number of wings that fall between the two vertical scores. , D are the pitches between the two vertical scores, respectively) and are synthetic resin caps formed in a positional relationship satisfying the above conditions.

[0010]

[Action]

 In the synthetic resin cap of the present invention, as described in claim 1, since the PP ring of the winged cap has an inclination score substantially parallel to the base end of the wing, the PP ring has a score. The probability of the score overlapping the wings when forming is reduced. In addition, in the inclined score, when the cap is opened, the resultant force (score breaking force) of the force in the opening direction and the force in the ascending direction acts almost at right angles to the score.

Further, in the cap according to claim 2, in the cap in which the wing and the interference convex portion are formed on the PP ring, two inclination scores substantially parallel to the base end of the wing are expressed by the formula ( n + 1) (p1 + p2) -np2-t> D> n (p1 + p2) + t (where p1 is the pitch between the wings, p2 is the distance between the wings and the interference projections, t is the width of the wings, and n is two) The number of wings that fall between the slope scores of D, D represents the pitch between the two slope scores, respectively.) Therefore, at least one of the slope scores is sure to be a wing or an interference projection. It can be formed without cost.

[0012]

【Example】

 Hereinafter, a synthetic resin cap of the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of the cap of the present invention, and the same components as those shown in FIGS. 5 and 6 are designated by the same reference numerals. This cap is roughly configured by a disc-shaped top plate portion 1 and a skirt portion 2 hanging from the peripheral edge thereof. A liner 16 is attached to the inner surface of the top plate portion 1. On the inner surface of the middle portion of the skirt portion 2, there is formed a screw 9 to be screwed with a screw at the mouth of the bottle to which the cap is attached. Ribs 3 are projected from the inner surface of the lower portion of the skirt portion 2. Each of the ribs 3 is formed in a rod shape having a substantially square horizontal cross section, and is projectingly provided on the inner surface of the skirt portion 2 such that the longitudinal direction thereof is along the longitudinal direction. A notch 12 is formed along the circumferential direction in the protruding portion of the rib 3 ... In the skirt portion 2 of the cap. The skirt portion 2 is divided by the cut 12 into a cylindrical portion 2a on the top plate portion 1 side and a PP ring 2b on the lower end side. A cap body 20 is formed from the top plate 1 and the cylinder 2a. The cap body 20 and the PP ring 2b are continuously connected only by the rib 3.

A plurality of wings 10 are projected on the inner surface of the PP ring 2b. These wings 10 have a substantially triangular plate shape, and are provided such that the tips thereof are located in the cap rotation direction A when the cap is opened and inside the cap. Further, the base ends of these wings 10 are provided so as to gradually incline toward the downstream side in the opening direction A toward the lower side.

The cap of this embodiment is characterized in that the PP ring 2 b is provided with an inclination score 40 substantially parallel to the base end of the wing 10. The inclination score 40 is weakened by making a cut in the perforation or in the thickness direction so as to be broken by the breaking force applied to the score when the PP ring 2b is turned in the opening direction. Has been formed.

This cap is used by being attached to the bottle mouth. When this cap is turned in the direction to attach it to the bottle mouth, when the wing 10 of the PP ring 2b hits the bottle mouth step, a force is applied to push the wing 10 in the rotation direction A when opening the cap. Depending on the direction, the wing 10 is further tilted to be in a tilted state when mounted, and the tip of the wing 10 is displaced outward. As a result, the PP ring 2b can ride over the stepped portion of the bottle mouth with almost no resistance. Then, when the wing 10 gets over the step of the bottle mouth, the wing 10 stands up to its original state and its tip is displaced inward, so that the wing 10 is locked under the step of the bottle mouth. To open the bottle with the cap attached, when turning the cap in the opening direction A, a force is applied to raise the wing 10, and the tip of the wing 10 tends to be displaced inward. Since the engagement state with the step portion is strongly maintained, the PP ring 2b cannot get over the step portion of the bottle mouth. On the other hand, since the cap main body 20 rises, the bridge forming rib 3 is cut, the PP ring 2b remains in the bottle mouth, and only the cap body 20 is removed from the bottle mouth. At this time, the tilt score 40 formed on the PP ring 2b has a resultant force F (score breaking force) of the force F1 in the opening direction and the force F2 in the rising direction as shown in FIG. And the inclination score 40 is broken by the score breaking force F. The PP ring 2b broken from the inclination score 40 becomes a band shape and is removed from the bottle mouth. Then, this indicates that the bottle has been opened.

According to this cap, since the PP ring 2b is provided with the inclined score 40 substantially parallel to the base end of the wing 10, the PP ring 2b is separated from the cap body 2a when the cap is opened. At the same time, the PP ring 2b is broken from the inclination score 40 and can be removed in a band shape from the bottle mouth, so that the PP ring 2b does not remain in the bottle mouth, and there is no trouble in reusing the bottle. In addition, since the PP ring 2b is removed once it has been opened, it is possible to easily determine the presence or absence of the opening. Further, since the inclination score 40 is provided almost parallel to the base end of the wing 10, when forming a score on the PP ring 2b, the probability that the inclination score 40 overlaps with the wing provided in parallel with it becomes small. It is possible to significantly reduce the incidence of defective formation. Further, in this inclination score 40, when the cap is opened, the score breaking force F, which is the resultant force of the force F1 in the opening direction and the force F2 in the ascending direction, is shown in FIG. 2 (a). Since it acts almost at right angles to the score 40, it is more susceptible to the score breaking force than the conventional vertical score 14 as shown in FIG. You will be able to break the score.

FIG. 3 shows a second embodiment of the cap of the present invention, and the same components as those shown in FIG. 1 are designated by the same reference numerals. This cap is configured with substantially the same components as the cap shown in FIG. 1 above, and is located in the vicinity of the place where each wing 10 is continuously provided, and on the side opposite to the cap rotation direction A at the time of opening the cap. An interference convex portion 30 is provided at the position, and two tilt scores 40a and 40b parallel to the base end of the wing 10 are formed on the PP ring 2b.

In these two inclination scores 40a and 40b, the positional relationship of each part shown in FIG. 4 is expressed by the following formula (A) (n + 1) (p1 + p2) -np2-t> D> n (p1 + p2) + t. ) (Where p1 is the pitch between the wings, p2 is the distance between the wings and the interference ridges, t is the width of the wings, n is the number of wings that fall between two slope scores, and D is the slope of two). It is formed in a positional relationship that satisfies the pitch between scores.

Further, the interference convex portion 30 is formed in a rectangular parallelepiped shape with the upper side cut out. Due to this shape, when the wings 10 are tilted in the opening direction, that is, when the wings 10 are in the tilted state at the time of mounting, the interference projection 30 has a lower portion where the tips of the adjacent wings 10 overlap. Has been done. Therefore, when the cap 10 is attached to the bottle mouth, the outward projection of the wing 10 which has fallen is not obstructed by the interference protrusion 30 for the adjacent wing 10, and the wing 10 has the bottle mouth step portion. You can get over with almost no resistance and the cap can be attached smoothly. Further, when the cap is rotated to open the cap, even if the wing 10 is bent to the side opposite to the cap opening direction, that is, even if the wing is reversed, the base of the wing is the interference protrusion 30. Ride on and prevent further deformation. Therefore, in this cap, even if the wing 10 is turned over when the cap is opened, the state in which the wing 10 is engaged with the bottle mouth step portion is maintained and the pill fur proof function is reliably achieved.

In the cap of this embodiment, the crossing convex portion is located in the vicinity of the position where the wings 10 provided on the PP ring 2b are connected to each other and on the side opposite to the cap rotation direction A when the cap is opened. 30 is provided, and two inclination scores 40a and 40b parallel to the base end of the wing 10 are formed on the PP ring 2b, and these two inclination scores 40a and 40b are expressed by the formula (A) (n + 1) (p1 + p2). -Np2-t> D> n (p1 + p2) + t (A) (where, p1 is the pitch between the wings, p2 is the distance between the wings and the interference projections, t is the width of the wings, and n is 2 lines) The number of wings that fall between the slope scores of the two, D represents the pitch between the two slope cores), so that the two slope scores formed on the PP ring 2b 40a and 40b do not contact the wings 10 and the interference protrusions 30. Even if one inclination score 40a is applied to the wing 10 or the interference convex portion 30, the other inclination score 40b is always located between the wing 10 and the interference convex portion 30, so that the PP ring 2b is surely secured. One slope score can be formed.

(Experimental Example 1) A cap having the inclination score 40 shown in FIG. 1 (hereinafter, referred to as an example) and a cap having a vertical score (hereinafter, referred to as a comparative example) were prepared, and the respective caps were formed. The score breakage rate when the cap of the cap was opened was examined. A polypropylene cap having the same structure as the cap shown in FIG. 1 was produced, and a cut score was formed between the wings of the PP ring in parallel with the wing base end to form an inclined core (Example). The main dimensions of this cap are as follows. Cap body outer diameter ...... 30mm Cap body portion height ...... 19mm PP ring outer diameter ...... 31.0 to 32.0mm PP ring inner circumference ...... 29 to 30.5mm PP ring height ...... 5.0mm PP Ring thickness …… 0.8-1.0mm Wing thickness …… 0.7mm Wing length …… 4.0mm Wing inclination angle …… 30 degrees Incline score inclination angle …… 30 degree Incline score length ...... 4.5 mm Depth of cut of inclination score ...... 0.5 to 1.0 mm On the other hand, the cap of the comparative example has a principal part which is exactly the same as the cap of the above-mentioned example, and the score is formed vertically. . The cut depth of the vertical score was the same as the tilt score of the example. In the production of the caps of these Examples and the caps of Comparative Examples, a score was formed based on the position of the wings. In the cap of the example, the failure occurrence rate at which the inclination score overlaps with the wing and does not break is 126/1000, whereas in the cap of the comparative example, the failure occurrence rate is as high as 640/1000. Met . Next, the caps of Examples and Comparative Examples, each having a good inclination score or vertical score, were attached to the bottle mouth of the same standard, and the cap was not torn off from the bottle mouth when the cap was opened. The success rate of score breakage was measured. The number of samples was 500 for each cap. As a result, the score breaking success rate of the cap of the example was 75%, whereas the score breaking success rate of the cap of the comparative example was 20%.

A cap having the same structure as the cap shown in FIG. 3 was manufactured. The dimensions of the main part are the same as those of the example cap in the above (Experimental example 1), and the interference occurs at a position in the vicinity of the position where the wings 10 are connected in series and on the side opposite to the cap rotation direction A when the cap is opened. While providing the convex portion 30, two inclination scores 40a and 40b parallel to the base end of the wing 10 were formed on the PP ring 2b. These slope scores were formed so as to satisfy the formula (A) (n + 1) (p1 + p2) -np2-t> D> n (p1 + p2) + t ... (A). Here, the dimensions of each part in the formula were set as follows. p1 (pitch between wings) …… 5.5mm p2 (spacing between wings and interference projections) …… 1.5mm t (width of wings) …… 0.7mm n (enter between two slope scores) Wing number) ... 1 piece D (pitch between two inclination scores) ... 10.0 mm Substituting these into equation (A), the pitch D between the two inclination scores is 11.8 to 7.7 mm. It suffices if it is any, and in the prototype example, two inclined cores were formed with D = 10.0 mm. As a result, at least one inclination score was formed for all prototype caps. Using the cap manufactured in this manner, a cap was attached to the bottle mouth and the success rate of score rupture when the cap was opened was measured as in (Experimental Example 1). As a result, the score rupture success rate was 90%, and the success rate was further improved as compared with the example cap in the above (Experimental Example 1).

[0023]

[Effect of device]

 As described above, the synthetic resin cap of the present invention comprises the top plate portion, the tubular portion hanging from the peripheral edge thereof, and the PP ring connected to the lower end of the tubular portion via the bridge, A screw is formed on the inner surface of the cylindrical portion, which is screwed into the screw of the bottle mouth, and a plurality of plate-shaped wings are located on the inner surface of the PP ring toward the tip in the cap rotation direction at the time of opening and inside the cap. In addition, in the synthetic resin cap provided so that the base end of the cap gradually inclines toward the downstream side in the cap opening direction, the PP ring is provided with an inclination score substantially parallel to the base end of the wing. Since it is provided, when opening the cap, the PP ring is separated from the cap body and is broken from the inclined score, the PP ring is removed from the bottle mouth in a band shape, and the PP ring does not remain on the bottle mouth. There is no hassle if you want to reuse the bottles. In addition, since the PP ring is removed after the plug is opened, it is possible to easily determine whether the plug is opened or not.

Further, in this cap, since the inclination score is provided almost parallel to the base end of the wing, when forming a score on the PP ring, the probability that the inclination score overlaps with the wing becomes small, and the defective rate of score formation occurs. Can be significantly reduced.

Further, in this inclination score, when the cap is opened, the score breaking force, which is the resultant force of the force in the opening direction and the force in the rising direction, acts on the inclination score at a right angle. Therefore, as compared with the conventional vertical score, the score is more susceptible to score breaking force, and it is possible to prevent score failure and reliably break the score.

Further, the cap of the present invention comprises a top plate portion, a tubular portion that hangs from the peripheral edge thereof, and a PP ring that is connected to the lower end of the tubular portion via a bridge, and is attached to the inner surface of the tubular portion. A screw to be screwed into the screw of the bottle mouth is formed, and a plurality of plate-shaped wings are located on the inner surface of the PP ring toward the tip in the cap rotation direction at the time of opening and at the inner side of the cap. In a synthetic resin cap that is installed so that it gradually inclines downward toward the downstream side in the cap opening direction, it is near the place where each wing is connected, and is opposite to the cap rotation direction when opening the cap. In addition to providing an interference convex portion at the position on the side, two inclination scores substantially parallel to the base end of the wing are given to the PP ring by the formula (n + 1) (p1 + p2) -np2-t> D> n (p1 + p2). + T (where p1 is the pitch between the wings) P, p2 is the distance between the wing and the interference projection, t is the width of the wing, n is the number of wings that fall between the two slope scores, and D is the pitch between the two slope scores.) Since the two slope scores formed on the PP ring do not affect the wings or the interference protrusions, it is assumed that one slope score affects the wings or the interference protrusions. However, the other inclination score is always located between the wing and the interference protrusion, and one inclination score can be reliably formed on the PP ring.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a first embodiment of a synthetic resin cap of the present invention.

FIG. 2 illustrates the action direction of the score breaking force at the time of opening the cap having the tilt score and the conventional cap having the vertical score. (A) shows the action of the score breaking force on the tilt score. FIG. 3B is an enlarged view of a main part showing a direction, and FIG. 3B is an enlarged view of a main part showing a direction in which a score breaking force acts on a vertical score.

FIG. 3 is a front sectional view showing a second embodiment of the synthetic resin cap of the present invention.

FIG. 4 is an enlarged view of an essential part for explaining the positional relationship of each part in setting the score forming condition of the cap.

FIG. 5 is a front sectional view showing an example of a conventional cap with wings.

FIG. 6 is a front sectional view showing an example of a conventional cap with wings.

[Explanation of symbols]

1 ... Top plate part, 2 ... Skirt part, 2a ... Cap body part, 2b ... PP ring (pill fur proof ring part), 3 ... Rib, 9 ... Screw, 10 ... Wing, 1
2 ... Notch, 30 ... Interference convex part, 40 ... Inclination score, 40a, 40b ... Inclination score, F1 ... Force in opening direction, F2 ... Force in upward direction, F ... Score breaking force, p1
...... Pitch between wings, p2 …… spacing between wings and interference projections, t …… width of wing, n …… number of wings between two slope scores, D …… between two slope scores Pitch.

Claims (2)

[Scope of utility model registration request] 1. A top plate part, a tube part hanging from the periphery of the top plate part, and a pill fur proof ring connected to the lower end of the tube part via a bridge. A screw that is screwed into the screw is formed, and a plurality of plate-shaped wings are located on the inner surface of the pill fur proof ring toward the tip in the cap rotation direction when opening and toward the inside of the cap, and the base end thereof is downward. In the synthetic resin cap provided so as to gradually incline toward the downstream side in the cap opening direction, the pill fur proof ring is provided with an inclination score substantially parallel to the base end of the wing. And synthetic resin cap. 2. A top plate part, a tube part hanging from the periphery of the top plate part, and a pill fur proof ring connected to the lower end of the tube part via a bridge, and the inner surface of the tube part of the bottle mouth. A screw that is screwed into the screw is formed, and a plurality of plate-shaped wings are located on the inner surface of the pill fur proof ring toward the tip in the cap rotation direction when opening and toward the inside of the cap, and the base end thereof is downward. In a synthetic resin cap that is provided so as to gradually incline toward the downstream side in the cap opening direction, in the vicinity of the place where each wing is connected, and on the opposite side of the cap rotation direction when opening the cap. In addition to providing an interference convex portion at the position of, the two tilt scores almost parallel to the base end of the wing are given to the pill fur proof ring by the formula (n + 1) (p1 + p2) -np2-t>D> n (p1 + p2 ) +
t (where p1 is the pitch between the wings, p2 is the distance between the wings and the interference protrusion, t is the width of the wings, n is the number of wings that fall between the two slope scores, and D is the slope score of the two) The caps made of synthetic resin are characterized in that they are formed in a positional relationship satisfying the above (individual pitches).