JPH0698649B2 - Stick manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stick manufacturing method for manufacturing a stick made of a synthetic resin material by injection molding instead of wooden disposable chopsticks.

[0002]

2. Description of the Related Art Recently, synthetic resin sticks have been used instead of wooden disposable chopsticks from the viewpoint of nature protection. The above-mentioned stick is usually injection-molded in such a manner that a pair of stick bodies arranged in parallel in close proximity to each other are continuously formed at one end thereof so as to be separable. The gate for resin introduction into the cavity shaped body,
For the purpose of realizing the uniform supply of resin to the cavity portions corresponding to both stick bodies, they are provided corresponding to the continuous portions of the stick body.

[0003]

The gate adopted here is a side gate formed along the parting line of the molding die, and communicates with the cavity from the spool through the inside of one molding die. There are tunnel gates, pin gates that communicate with the cavity from the direction orthogonal to the parting line, etc. In both cases, if the size is adjusted to the amount supplied to the cavity, the planned stick division The cross-sectional area becomes large and it becomes difficult to cut by hand.

In other words, it is necessary to make the gate small in order to make the cross-sectional area of the divided portion of the stick as small as possible and to easily divide the stick (in the case of the pin gate, it is structurally large). However, it is difficult to supply the resin, so it is necessary to impose a limit on the size of the stick body or set the injection pressure high to forcefully introduce the resin into the cavity, because the resin supply becomes difficult. There is. The former treatment may lose practicality in consideration of the general usage pattern of the product. In addition, the latter treatment involves considerable difficulty in mold making, especially in a continuous portion of the stick, it is difficult to accurately form a gate at a divided portion of the stick, and a cavity portion corresponding to each stick body is formed. There is a risk that it will not be possible to ensure a uniform resin supply to the resin. Further, when a side gate or a tunnel gate is used, even if the resin can be supplied well, dust is generated when the gate is cut, which may attach to the product and cause stains.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a weld line is formed in a portion where resins separately injected in a cavity come into contact with each other, and the strength of the portion is significantly lowered. Focusing attention, form a gate of sufficient size for each cavity part corresponding to each stick body so that the above-mentioned weld line may be generated at the divided part of the stick, and in a molding-friendly way, An object of the present invention is to provide a stick manufacturing method capable of easily manufacturing a stick that can be easily broken with high yield.

[0006]

Therefore, in the present invention,
In a stick manufacturing method of molding a stick in which a pair of stick bodies arranged in parallel in close proximity to each other so that they can be divided at one end thereof by injection molding, a stick is divided into continuous parts of the stick body. The cavity of the molding die is formed so that the cross-sectional area of the part is as small as possible, and at the position where the resin reaches the above-mentioned divided parts evenly, the cavity part corresponding to each stick body is attached. The independent gates are made to communicate with each other, and the synthetic resin material is injected and molded through the gates.

In this case, in particular, the pin gates are respectively communicated with the cavities corresponding to both stick bodies adjacent to the divided portion, and the continuous portions on both sides of the divided portion are narrowed toward the divided portion. A portion of the cavity may be formed to have a shape.

[0008]

As a result, since there is no restriction in reducing the cross-sectional area of the above-mentioned divided portion as much as possible, the condition that a weld line is generated at that portion is combined with the accurate division at the divided portion. Moreover, it is possible to provide a product in which the stick can be easily handed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the manufacturing method of the present invention will be specifically described below with reference to the drawings. The drawing shows a molding die for forming a stick in which a pair of stick bodies arranged in parallel with each other in close proximity to each other is separable at one end thereof. The cavities of the molding die are the cavity portions 1 and 1 corresponding to the respective stick bodies.
Are arranged in parallel and formed over the upper and lower mold members 2, 3. Then, one end of each of the cavity portions 1 and 1, that is, a portion corresponding to the top portion of the stick body in this embodiment, is formed with a V-shaped continuous portion 1A in plan view so as to be continuous with each other at a divided portion D. 1A is formed. Further, pin gates 4 and 4 are respectively communicated with the cavity portions 1 and 1 at equal distances to the continuous portion through the upper mold member 2, and at the time of injection molding, the pin gate 4 from the spool 5 is connected. Synthetic resin is introduced into the cavity portions 1 and 1 through the holes 4 and 4.

In this case, the cross-sectional area A of the divided portion D is
As shown in FIG. 3, the mold is formed so as to be as small as possible. And as a result of injection molding,
Since the synthetic resin is filled in each of the cavity portions 1 and 1 and simultaneously reaches the divided portion D through the continuous portions 1A and 1A thereof, a weld line is generated here. The stick molded in this way is
Since the strength of the divided portion D is low, it is easy to divide the hand, and moreover, it is possible to surely divide the portion. Further, in this embodiment, since the pin gate is adopted,
Contrary to the case where a gate such as a side gate or a tunnel gate is adopted, dirt of dust caused by cutting the gate can be avoided.

In the above embodiment, the gates 4 and 4 are connected to the cavity portion 1 at a position relatively close to the continuous portion.
However, it may be provided at a remote position, for example, at the opposite end of the cavity portion. When a side gate or a tunnel gate is adopted, each of the continuous portions 1A, 1A described above is used.
The gates may be communicated with each other.

[0012]

As described above in detail, the present invention forms the cavity of the molding die so that the cross-sectional area of the divided portions of the continuous portions of both stick bodies is as small as possible.
At a position where the resin reaches the divided parts evenly, an independent gate is made to communicate with the cavity portion corresponding to each stick body, and a synthetic resin material is injected and molded through the gate. The effect of forming a gate of a sufficient size for each cavity corresponding to each stick body, and manufacturing a stick that is easy to divide in a reasonable shape in molding and with good yield Is obtained.

[Brief description of drawings]

FIG. 1 is a plan view of an opened molding die showing an embodiment of the manufacturing method of the present invention.

FIG. 2 is a sectional view taken along the line II of the above embodiment.

FIG. 3 is a sectional view taken along line II-II of the above embodiment.

FIG. 4 is a plan view of a stick formed in the above embodiment.

[Explanation of symbols]

 1, 1 cavity part 1A, 1A continuous part 2, 3 type member 4, 4 pin gate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B29L 31:44 4F

Claims (3)

[Claims] 1. A method for manufacturing a stick, wherein a pair of stick bodies, which are arranged in close proximity to each other and are parallel to each other, are separably connected at one end thereof by injection molding. The cavity of the molding die is formed so that the cross-sectional area of the divided part of the continuous part of is as small as possible, and it corresponds to each stick body at the position where the resin reaches the divided part evenly. A method for manufacturing a stick, characterized in that an independent gate is communicated with the cavity portion to be formed, and a synthetic resin material is injected through the gate and molded. 2. A pin gate is connected to a cavity portion corresponding to both stick bodies adjacent to the divided portion, and the continuous portions on both sides of the divided portion are narrowed toward the divided portion. The method for manufacturing a stick according to claim 1, wherein a portion of the cavity is formed as described above. 3. A stick in which a pair of stick bodies arranged in parallel with each other in close proximity to each other are separably connected at one end thereof, and a synthetic resin is injected by injection molding into both stick bodies adjacent to the divided portion. A stick characterized by a structure in which there is a portion and the continuous portion of the stick body is formed so as to be narrowed toward the divided portion.