JPH0286417A - Manufacture of tubular body with one end sealed - Google Patents

Abstract

PURPOSE:To obtain a tubular body almost free from ununiformed sections by inserting a rodlike core pin sharp in the tip into a die correspondent to the outer shape of the tubular body to be molded so that the core pin is not brought into contact with the die and injecting molten resin through a gate oppositely provided to the tip of the core pin. CONSTITUTION:A die 21 has an inner shape correspondent to the outer shape of a tubular body 1' and both a projecting annular part edge 25 correspondent to a contricted part 2 and a gate 24 for forcedly feeding resin are formed. Firstly molten resin forcedly fed into a molding chamber from the gate 24 is allowed to collide against the tip of a core pin 23 but the tip is sharpened in a conical shape and therefore resistance is made small and molten resin is uniformly split around the core pin and smoothly allowed to flow. As a result, the pressure exerted on the core pin 23 is made small and therefore the core pin 23 is not shifted from the ordinary position and injection-molding is performed and the homogeneous tubular body free from ununiformed sections is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a tubular body, particularly a tubular body that is sealed at one end.

[Conventional technology]

Tubular bodies with one end sealed are used for various purposes, such as test tubes and the like. Examples thereof are shown in FIGS. 4 to 7.

FIG. 4 is a sectional view of a tubular body made of an injection molded body of synthetic resin, for example PvC. As shown, one end thereof is sealed and the other end is open. Further, an annular constriction 2 is formed in a predetermined position in the circumferential direction. This tubular body 1 is used in a continuous ambulatory peritoneal dialysate container (bag) shown in FIG.

FIG. 5 shows the bag partially in section. In the same figure, 1
0 is the bag body. The bag body 10 is made of a soft vinyl chloride resin sheet (soft PV
It is manufactured by joining the edges 12 of C sheet) 11.11' by heat sealing. The accommodation space 13 thus formed within the bag body accommodates an infusion preparation such as Ringer's solution.

The tubular body 1 shown in FIG. 4 is attached to the lower edge of the bag body 10. The tubular body 1 is inserted between the PVC sheets 11 and 11' from the sealed end side, and is fused and fixed to the sheets. A conduit 14 made of soft PvC is connected to the open end of the tubular body 1 . Furthermore, a cylindrical body 15 is provided at the lower edge of the bag body 10 for a medical solution mixed injection port.

The cylindrical body 15 is also made of PvC, and the PvC sheet 11
．． 11' and is fused and fixed. The cylindrical body 15 is open at both ends, and the open end located outside the storage space 13 is sealed with a rubber stopper 16.

When performing peritoneal dialysis treatment using the conventional bag described above, the procedure is as follows.

First, a needle of a syringe is inserted into the rubber stopper 16, and necessary medical solutions such as insulin and antibiotics are co-injected into the bag. In addition, the tubular body 1 is photographed from above the bag body 10,
As shown in FIG. 7, the portion 11 above the constricted portion 2 is broken off. As a result, the accommodation space 13 and the conduit 14 communicate with each other via the remaining portion 12 of the tubular body, and the dialysate filled inside can be poured out. The bag in this state is suspended at a high position, and the dialysate in the bag body 10 is injected into the patient's abdominal cavity by gravity through a tube connected to the tip of the conduit 14 and placed in the patient's abdominal cavity.

By the way, the tubular body shown in FIG. 4 has been conventionally manufactured by injection molding as shown in FIG. 8, for example.

In FIG. 8, 21 and 22 are molds, and 23 is a core pin. The mold 21 has an inner surface shape corresponding to the outer shape of the tubular body 1, and is provided with an annular white edge 25 corresponding to the constricted portion 2. Further, a gate 24 for press-fitting resin is formed. The core pin 23 has a shape corresponding to the internal space of the tubular body 1 and has a flat top. As shown,
After closing the mold and forming a predetermined molding space, gate 2
From step 4, PvC is press-fitted and injection molding is performed.

[Problem to be solved by the invention]

The conventional manufacturing method for obtaining the tubular body 1 has the following problems.

That is, since the top surface of the core pin 23 is flat, the gate 2
4, the resistance to the resin flow press-fitted into the molding chamber is large. For this reason, as shown in FIG. 9, the core pin 23 may tilt due to pressure from the resin flow indicated by the arrow in the figure. As a result, uneven thickness occurs in the obtained tubular body 1, and the constricted portion 2
There is a problem that it becomes easy to bend.

An object of the present invention is to prevent the core pin 23 from tilting when manufacturing the tubular body 1 by injection molding, and to obtain a product having a uniform wall thickness without uneven thickness.

[Means to solve the problem]

In order to solve the above problems, in the present invention, the top of the core pin is sharpened to reduce resistance to resin flow and prevent the core pin from tilting.

That is, in the method of manufacturing a tubular body with one end sealed according to the present invention, a mold having an inner surface shape corresponding to the outer shape of the tubular body to be molded is provided with an outer shape corresponding to the shape of the internal space of the tubular body. A rod-shaped core pin with a sharp tip is inserted into the mold so as not to touch the mold, and a resin melt is injected around the core pin from a gate provided in the mold so as to face the pointed end of the core pin. The method is characterized in that a molten resin is filled between the inner surface of the mold and the outer surface of the core pin and then cured.

[Effect]

When manufacturing a tubular body by the method of the present invention, the resin flow press-fitted from the gate of the mold hits the tip of the core pin as in the conventional manufacturing method. However, in the case of the present invention, since the tip of the core pin is sharp, the resin flow receives little resistance and is smoothly injected into the molding chamber. Therefore, the resistance applied to the core pin is also reduced, and the inclination as shown in FIG. 9 does not occur.

〔Example〕

FIG. 1 is a diagram showing an embodiment in which the present invention is applied to the manufacture of a tubular body used as an outlet of a bag used for peritoneal dialysis. In this figure, the same parts as in FIG. 8 are given the same reference numerals. That is, 21° and 22 are molds, 23 is a core pin, and 24 is a gate.

As shown in the figure, the mold used in this example has a core pin 2.
The mold is exactly the same as the mold used in FIG. 8, except that the tip of No. 3 is conically pointed. Molten PVC is press-fitted into the molding chamber through the gate 24 of this mold to perform molding.

Figure 2 shows PvC press-fitted into the molding chamber from the gate 24.
It shows the flow. As shown, the PvC flow hits the tip of the core pin 23. However, since this tip is conically pointed, the resistance to the PvC flow is significantly smaller than if the tip was flat as shown in FIG. Also,
As shown in the figure, the PvC flow is evenly divided around the core pin and flows smoothly. As a result, core pin 23 becomes Pv
The pressure received from the C flow is small, and there is no force in a direction that would cause an inclination. Therefore, injection molding is performed without the core pin 23 shifting from its normal position, and a tubular body with uniform wall thickness without uneven thickness can be obtained.

An example of the tubular body obtained using the method of the above example is shown in the third example.
As shown in the figure. In the figure, 1' is the tubular body manufactured in the above embodiment. The internal space of the tubular body 1' corresponds to the outer shape of the core pin 23 used, and the space on the sealed end side has a conical shape. Further, a constricted portion 2 is formed on the outer periphery at a predetermined position.

The constricted portion 2 is an annular white edge 25 provided on the inner surface of the mold 1.
It corresponds to

Further, a sleeve-shaped outer tube 3 is provided on the open end side of the annular body 1'.
is provided. The outer tube 3 may be manufactured separately from the tubular body 1 and fixed by heat fusion, for example. Furthermore, by using a suitable mold, it is also possible to integrally mold the outer tube 3. This outer tube 3 is used to connect a conduit 14 in the infusion bag shown in FIG. That is, the tubular body 1'
A conduit 14 is inserted between the outer tube 3 and the outer tube 3. If sterilization is performed in an autoclave in this state, the conduit 1 will
4 is fused and joined to the outer tube 3 and the tubular body 1'.

In addition, although the above embodiment describes the production of a tubular body used for the spout of a bag used for peritoneal dialysis, the present invention can also be applied to the production of other tubular bodies with one end sealed, such as test tubes and blood collection tubes. The same can be applied.

〔Effect of the invention〕

As detailed above, according to the present invention, when manufacturing a tubular body with one end sealed by injection molding of synthetic resin, uneven thickness can be prevented and a product with uniform wall thickness can be obtained. effect can be obtained.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining an embodiment of the manufacturing method according to the present invention, and FIG.
A cross-sectional view showing an example of a tubular body obtained by applying the example,
FIG. 4 is a cross-sectional view of a conventional tubular body. Figures S5 to C are diagrams for explaining a bag used for peritoneal dialysis using this tubular body, the first diagram shows the conventional manufacturing method of the tubular body, and the first diagram shows the problems. It is a diagram. 1.1'... Tubular body, 2... Constriction, 3... Outer tube, 10... Infusion bag body, 11.11'... Soft PVD sheet, 12... Edge, 13...Storage space,
14... Conduit, 15... Cylindrical body, 16... Rubber stopper, 21° 22... Mold, 23... Core pin, 24...
...Gate, 25...ring-shaped white edge. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] In a mold having an inner surface shape corresponding to the outer shape of the tubular body to be molded, a rod-shaped core pin having an outer shape corresponding to the shape of the internal space of the tubular body and having a sharp tip is placed in such a way that it does not touch the mold. Insert the resin melt around the core pin from a gate provided in the mold so as to face the tip of the core pin, and fill the space between the inner surface of the mold and the outer surface of the core pin with the resin melt. 1. A method for manufacturing a tubular body with one end sealed, the method comprising: curing the tubular body at one end;