JP2002187172A - Method for manufacturing clip made of synthetic resin and clip made of synthetic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the holding force of a clip made of a synthetic resin and to suppress the manufacturing cost of the clip made of the synthetic resin. SOLUTION: A pair of holding pieces 1 and the bent parts 2 connecting the holding pieces 1 are integrally molded from a synthetic resin. A proper number of shrink strains S are provided to the inside surfaces of the bent parts 2. A locking rib 5 is provided to the inside of the leading end part of either one of or both of the holding pieces 1 along the longitudinal direction of the leading end part. Anti-slip emboss processing 6 is applied to either one of or both of the holding pieces 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clipping device in which the opening of a clip is forcibly opened when the clip is pushed out by a predetermined pressing tool, and the opening is closed by the elastic force of the clip itself after being pushed out. The present invention relates to a method for manufacturing a formed synthetic resin clip and a synthetic resin clip.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 58-4698 discloses a clip in which a pair of holding pieces and a bent portion are integrally formed by a single elastic plate, and a widening ear is formed on the left and right ends of the holding pieces. Have been. This clip is pushed out in a state where the opening of the clip is opened by a predetermined pressing tool,
It is used as a clip for holding paper or the like in the opening. The clip of the present invention is formed by bending an elastic plate. At present, the clip is formed by bending a metal plate, and is commercially available.

[0003]

When a clip is formed by bending a tough material such as a metal material, a piece of paper or the like can be sufficiently clamped. However, when this clip is injection-molded with a synthetic resin, the holding force of the holding piece becomes extremely weak, and it has been difficult to put it to practical use like a metal clip. In particular, it has been found that the strength of the bent portion and the elasticity of the holding piece are extremely inferior to those of the metal clip.

In addition, in the case of molding using an injection molding machine, after the molded product is cut off, a projecting portion remaining at the boundary portion between the gate opening of the mold and the product is manually cut off one by one, a so-called gate. An operation called processing is required. This operation also increases the manufacturing cost of clips molded from synthetic resin. Therefore, in order to mold this kind of clip with a synthetic resin, it is necessary to increase the clamping force of the clip to the level of a metal clip and to reduce the manufacturing cost.

The inventor of the present invention has made intensive studies to increase the gripping force of the synthetic resin by effectively reflecting the shrinkage characteristic of the synthetic resin upon the gripping force of the clip. Based on the standpoint that the problem can be solved, a technology that uses the setting of the spacing between the holding pieces when molding the tip of the holding piece and the distortion called so-called sink mark that occurs when the bent portion contracts is developed. It is. That is, an object of the present invention is to provide a synthetic resin clip manufacturing method and a synthetic resin clip that can increase the clamping force of the synthetic resin clip and reduce the manufacturing cost of the synthetic resin clip.

[0006]

According to a first manufacturing method of the present invention, a pair of holding pieces 1 and a bent portion 2 connecting the holding pieces 2 are integrally formed of synthetic resin. This is a method for manufacturing a synthetic resin clip in which the expanding ears 3 are formed to project from the left and right ends of the holding piece 1. In this manufacturing method, the inner distance between the tips of the holding pieces 1 is set to 0.1 mm to 0.6 mm with the core pin P for sliding forming the holding pieces 1 during injection molding. Further, the thickness of the bent portion 2 is set to 1 mm to 3 mm in the injection molding die Q. Then, this is a manufacturing method in which the distal end portion of the holding piece 1 is crimped by the contraction of the bent portion 2 accompanying the curing of the synthetic resin after the core pin P and the mold Q are removed.

According to this manufacturing method, the inner space of the holding piece 1 is reduced to 0.1 due to the shrinkage of the bent portion 2 accompanying the curing of the synthetic resin.
Shrinkage starts at an interval of 1 mm to 0.6 mm, and this interval gradually closes, and finally the holding pieces 1 come into contact with each other to generate a strong crimping force. Further, when the thickness of the synthetic resin of the bent portion 2 is set to 1 mm to 3 mm, when the bent portion 2 contracts, a shrinkage distortion called so-called sink occurs inside the bent portion 2. This distortion during contraction occurs when the thickness of the bent portion 2 is set to 1 mm or more. Then, due to the sink mark, the inside of the longitudinal center portion of the bent portion 2 contracts more than the both ends of the bent portion 2, and the distortion at the time of the contraction increases the strength of the bent portion 2, and the holding piece 1 To enhance the crimping force.

In the second manufacturing method, a pair of holding pieces 1 and a bent portion 2 for connecting the holding pieces 2 are integrally formed of synthetic resin. This is a method for manufacturing a protruding synthetic resin clip. In this manufacturing method, the thickness of the left and right end portions of the bent portion in the injection molding die Q is set to be thicker than the thickness of the central portion in the longitudinal direction, and shrinkage of the bent portion 2 due to curing after the die Q is removed. This is a manufacturing method in which the strength of the left and right ends of the bent portion 2 is increased by distortion. As described above, when the thickness of the both end portions of the bent portion 2 is made thicker than the center portion of the long portion, distortion at the time of contraction called shrinkage occurs at each of the both end portions. Then, the strength of both longitudinal ends of the bent portion 2 is inevitably increased, and the crimping force of both ends of the holding piece 1 continuous to the bent portion 2 is naturally increased.

The third means is that, in the bent portion 2, the longitudinal center portion of the outer surface of the bent portion 2 is recessed from both ends, and a pair of tapers 4 are provided from the center portion inclining in the direction of each holding piece. This is a manufacturing method in which a parting surface of an injection molding die Q and a gate port Q1 are provided at a boundary of a taper 4 and injection molding is performed. By providing the gate opening Q1 of the injection molding die Q at the boundary of the taper 4, the protruding portion remaining at the boundary between the gate opening and the product becomes a slight flat protrusion.

The fourth means relates to a synthetic resin clip in which a pair of holding pieces 1 and a bent portion 2 for connecting the holding pieces 2 are integrally formed by a synthetic resin. In this clip, an appropriate number of contraction strains S are provided on the inner surface of the bent portion 2, and a locking rib 5 along the longitudinal direction of the tip portion is provided inside one or both tip portions of the holding piece 1.
It is that it protruded. The locking ribs 5 strongly support a piece of paper or the like held between the holding pieces 1.

The fifth means is a means for solving the problem in that in the clip made of synthetic resin, one or both of the holding pieces 1 are provided with anti-slip crimping processing 6 on the inner side of the distal end.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. The clip of the present invention is a clip in which a pair of holding pieces 1 and a bent portion 2 for connecting the holding pieces 2 are integrally formed with a synthetic resin. (See FIGS. 2 and 3). As the synthetic resin, a thermoplastic such as polycarbonate is used.

The method of manufacturing the clip according to the present invention is based on an injection molding method. The inner distance H between the tips of the holding pieces 1 is set to 0.1 mm to 0.6 mm with the slide core pin P forming the holding pieces 1.
(See FIG. 1). When the synthetic resin is injected into the mold Q and the core pin P is pulled out, the inner space H at the tip of the holding piece 1 is opened at an interval of 0.1 mm to 0.6 mm (see FIG. 2). Thereafter, as the synthetic resin cures, the distance gradually narrows and contacts, and after 48 to 72 hours when the molecular structure of the material is stabilized, a pressing force is generated between the sandwiching pieces 1. In the experiment, the crimping strength was highest when the inner distance H was set to 0.3 mm.
Due to the relationship with the wall thickness, the pressure changes slightly. Therefore, even if the size of the entire clip is changed within the range currently in practical use, the inner distance H between the front end portions of the holding pieces 1 is set to 0.
It has been found that by setting the thickness to 1 mm to 0.6 mm, a crimping force usable as a practical clip can be obtained.

On the other hand, the thickness L of the bent portion 2 is set to 1 mm to 3 mm in the injection molding die Q (see FIG. 2). The reason why the thickness L of the bent portion 2 is set to 1 mm or more is that a shrinkage strain S called sink mark is generated from the thickness L due to the curing of the synthetic resin (see FIGS. 3 and 4). This shrinkage strain S distorts the design dimensions of the product C, and is not a desirable phenomenon in ordinary injection molding. However, paying attention to the fact that when the shrinkage strain S called sink mark occurs, the strength of the strained portion is increased, and by intentionally generating the shrinkage strain S in the bending portion 2, the strength of the bending portion 2 is strengthened and 1
The crimping force is increased. The reason why the thickness of the bent portion 2 is set within 3 mm is that the thickness is set from the maximum size (13.3 × 17.9 mm) of this kind of clip currently in practical use. Therefore, when the size of the clip is set to an unprecedented size, the thickness of the bent portion 2 may be set to 3 mm or more. Further, when the bent portion 2 is formed, the outer curve 2C of the bent portion 2 is set to be large, and the inner curve 2D formed inside the bent portion 2 is set so as to be as close to a perfect circle as possible. 1 can increase the pressing force.

When the thickness of the left and right end portions 2A of the bent portion 2 is set to be thicker than the thickness of the longitudinal center portion 2B in the injection molding die Q, the left and right end portions 2A of the bent portion 2 are set.
A contraction strain S can be generated on the inner surface of A. However, the thickness of the left and right ends 2A must be set to 1 mm or more as described above. Therefore, in order to generate the contraction strain S on both the left and right end portions 2A of the bent portion 2, the thickness of the left and right end portions 2A is set to 1 mm or more, and the thickness of the central portion 2B is set to 1 mm or less. By setting the thickness of the left and right end portions 2A in this manner, strong contraction and hardening due to the contraction strain S occurs in the left and right end portions 2A of the bent portion 2 and, accordingly, the crimping force of the left and right ends of the holding piece 1. (See FIG. 3).

Further, in the bent portion 2, a longitudinal center portion of the outer surface of the bent portion 2 is recessed from both ends, and a pair of tapers 4 are provided from the center portion inclining in the direction of each holding piece (see FIG. 2). The boundary of the taper 4 is defined as the parting surface Q2 of the mold Q, and the gate of the injection molding mold Q is provided at the boundary of the taper 4 (see FIG. 1). When the molded product C is cut off after the injection molding, the protruding portion C1 remaining at the gate port Q1 and the boundary portion of the taper 4 becomes a slightly flat protruding portion C1 (see FIG. 2). Moreover, since the gate port Q1 is provided at the top of the taper 4, the operation of separating the product C from the flat protruding portion C1 can be performed very easily. Further, after the product C is separated, the protruding portion C1 is extremely small, so that there is no problem in using the product C as it is. Moreover, this protruding portion C1 is
Since it remains in the recess of the central portion 2B, there is no need for gate processing. As a result, all the labor and cost required for this gate processing can be saved.

The clip of the present invention is obtained by integrally molding the pair of holding pieces 1 and the bent portion 2 connecting the holding pieces 2 with each other. This is the clip that caused S (see FIGS. 2 and 3). Further, when a locking rib 5 is provided on the inside of one or both ends of the clip 1 of the clip along the longitudinal direction of the tip, the tip of the clip 1, particularly the crimping force, is strong. The pinching force of the left and right ends and the pinching force of the locking rib 5 can act on each other (see FIG. 2). The illustrated locking rib 5 is provided on one of the holding pieces 1, and the other holding piece 1 is provided with a fitting recess 7 into which the locking rib 5 is fitted. When the locking rib 5 and the fitting recess 7 are formed as a pair in this manner, even a single piece of paper can be reliably held. Further, the locking ribs 5 may be formed on both of the holding pieces 1, and the number of the locking ribs 5 can be set arbitrarily.

Reference numeral 6 denotes a non-slip textured surface 6 provided on the inside of one or both ends of the holding piece 1 (see FIG. 2). This embossing 6 is provided on the surface of the holding piece 1 which is in contact with the paper piece, and may be provided on the surface of the locking rib 5. The embossing 6 increases the coefficient of friction on the contact surface with the sandwiched paper piece.

[0019]

According to the present invention, the above object has been attained. That is, the inner distance between the tips of the holding pieces 1 is set to 0.1 mm to 0.6 mm by the slide core pin P which forms the holding pieces 1 at the time of injection molding, and the thickness of the bent portion 2 is set to 1 mm by the injection molding die Q. After the core pin P and the mold Q are removed, the bent portion 2 contracts due to the hardening of the synthetic resin after the core pin P and the mold Q are removed. 1 was able to increase the pressing force.

The thickness of the left and right ends of the bent portion of the injection molding die Q is set to be larger than the thickness of the central portion in the longitudinal direction, and the bent portion 2 accompanying the hardening of the synthetic resin after the die Q is removed. According to the manufacturing method of increasing the strength of the bending portion 2 on the left and right due to the shrinkage strain of the holding piece, the pressing force on the left and right ends of the holding piece 1 can be increased. As a result, a clamping force comparable to the clamping force of a conventional metal clip can be obtained.

Further, in the bent portion 2, a longitudinal center portion of the outer surface of the bent portion 2 is recessed from both ends, and a pair of tapers 4 inclined from the center portion toward each holding piece are provided. Parting surface Q of mold Q for injection molding
When the molded product C is separated by providing injection molding by providing the gate port Q1 and the gate port Q1, the protrusion C1 remaining at the boundary between the gate port Q1 for injecting the synthetic resin into the mold Q and the product is extremely small. Was successful. Moreover,
Since the protruding portion C1 is formed in a portion in which the longitudinal center portion of the outer surface of the bent portion 2 is recessed from both ends, it can be used without any problem in using it as a clip even when it is left as it is. . Therefore, there is no need to cut off the protruding portion C1 which has been a problem in the production of the synthetic resin clip, and the production cost of the synthetic resin clip can be reduced.

In the clip of the present invention, an appropriate number of shrinkage strains S are provided on the inner surface of the bent portion 2, and one or both of the holding pieces 1 are provided inside the tip portion along the longitudinal direction of the tip portion. Since the locking rib 5 is protruded, the pressing force of the holding piece 1 obtained by the bent portion 2 and the holding force of the locking rib 5 interact with each other to firmly hold the sandwiched paper piece and the like. Can be supported.

The slipping of the paper pieces and the like held therebetween is prevented by the anti-slip graining processing 6 applied to the inside of one or both of the tips of the holding pieces 1 of the clip of the present invention.

As described above, according to the present invention, various industrially useful effects such as an increase in the clamping force of the synthetic resin clip and a reduction in the manufacturing cost of the synthetic resin clip can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing a setting state of a slide core pin at the time of injection molding in a manufacturing method of the present invention.

FIG. 2 is a longitudinal sectional view showing one embodiment of the clip of the present invention.

FIG. 3 is a plan view showing an embodiment of the clip of the present invention.

FIG. 4 is a plan view showing another embodiment of the clip of the present invention.

[Explanation of symbols]

 C Product C1 Projecting portion H Inner interval L Thickness P Core pin Q Mold Q1 Gate opening Q2 Parting surface S Shrinkage strain 1 Nipping piece 2 Bend 2A Left and right ends 2B Center 2C Outer curve 2D Inner curve 3 Spreading ear 4 Taper 5 Locking rib 6 Texture processing 7 Fitting recess

Claims (5)

[Claims] 1. A method of manufacturing a synthetic resin clip in which a pair of holding pieces and a bent portion for connecting the holding pieces are integrally formed of synthetic resin, and expansion ears are formed to project right and left ends of the holding pieces. In, the inner spacing of the tip of the holding piece is 0.1 mm with the core pin for the slide that forms the holding piece during injection molding
And 0.6 mm, and the thickness of the bent portion is set to 1 mm to 3 mm in the injection mold, and the pinch piece is shrunk by the shrinkage of the bent portion due to the hardening of the synthetic resin after removing the core pin and the mold. A method for producing a synthetic resin clip, comprising crimping a tip portion. 2. A method for manufacturing a synthetic resin clip in which a pair of holding pieces and a bent portion connecting the holding pieces are integrally formed by a synthetic resin, wherein the left and right ends of the bent portion are formed by an injection molding die. The synthetic resin is characterized in that the thickness is set to be thicker than the thickness of the central part in the longitudinal direction, and the strength of the right and left ends of the bent part is increased by contraction distortion of the bent part due to curing of the synthetic resin after removing the mold. Method of manufacturing clips. 3. In the bent portion, a longitudinal central portion of the outer surface of the bent portion is recessed from both ends, and a pair of tapers inclined from the central portion in the direction of each holding piece are provided. 3. The method for producing a synthetic resin clip according to claim 2, wherein a parting surface of the mold and a gate port are provided and injection molding is performed. 4. In a synthetic resin clip in which a pair of holding pieces and a bent portion connecting the holding pieces are integrally formed with a synthetic resin, an appropriate number of shrinkage strains are provided on the inner surface of the bent portion, and the holding is performed. A clip made of synthetic resin, characterized in that a locking rib extending along the longitudinal direction of the distal end portion is provided inside one or both distal ends of the pieces. 5. The synthetic resin clip according to claim 4, wherein an inner surface of one or both of the holding pieces is subjected to anti-slip embossing.