JP2002225095A - Injection mold for syringe cylinder made of synthetic resin, molding method, and syringe cylinder made of synthetic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection mold which can mold at a high molding speed and is capable of providing a syringe cylinder made of a synthetic resin having little flaw. SOLUTION: A gate G is provided so as to communicate with the side part of a flange molding cavity being the end part on the side of the fixed template of a cylinder molding cavity 18 from the side part of the end part 14a on the side of the movable template 10 of a hot runner nozzle 14. A region, where the cylinder molding cavity 18 and the hot runner nozzle 14 are arranged so as to be superposed one upon another side by side, can be reduced to the utmost. A cooling water pipe 19 can be arranged so as to uniformly surround the periphery of the cylinder molding cavity 18. The uniformization of the shrink speed of the resin can be accelerated and warpage or falling generated at the time of shrinking can be prevented. A molding speed can be increased to the utmost and productivity can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal mold for injection molding of a synthetic resin syringe cylinder, a molding method, and a synthetic resin syringe cylinder.

[0002]

2. Description of the Related Art In a syringe, a plunger is pushed into a cylinder in which an injection needle is mounted on a cylindrical projection at a distal end, thereby forming a drug solution enclosing portion. In recent years, synthetic resin syringes have become widespread for disposable use. In general, a mold for injection molding of a syringe cylinder made of a synthetic resin uses a cold runner or a semi-hot runner combining a cold runner and a hot runner.

However, in these systems in which a cold runner is employed at least in part, the resin in the cold runner portion must be discarded for each molding cycle, resulting in a large loss.
In addition, there are limits to the molding speed and the number of molded products.

[0004]

Therefore, a direct hot runner type mold having no cold runner portion can be considered. That is, a core extending from the movable mold plate is inserted into a concave portion of the fixed mold plate to form a cavity for molding a cylinder, and a hot runner nozzle with a built-in heater extending from the fixed mold plate is provided at an end on the movable mold plate side. A gate is provided, through which the molten resin is filled from a cavity corresponding to the end of the body near the flange of the cylinder.

[0005] However, in this case, the hot runner nozzles are arranged in parallel so as to overlap the sides of the cavity, so that it is impossible to arrange a cooling pipe in a portion where the hot runner nozzles are arranged. That is, it becomes impossible to arrange a cooling pipe around the cavity. Therefore, at the time of cooling, the temperature distribution of the resin in the cavity differs between the hot runner nozzle side and the opposite side, and as a result, the contraction speed differs. For this reason, the syringe cylinder, which is a molded product, is likely to warp or fall.

This tendency becomes more remarkable as the molding speed is increased. Therefore, there is a problem that the molding speed cannot be increased and productivity is poor. On the other hand, when the gate of the hot runner nozzle is provided corresponding to the portion corresponding to the body of the syringe cylinder as described above, the following problem occurs. That is, after one cycle of molding, the solidified resin chip may remain at the molten resin injection port of the hot runner nozzle, and this chip is extruded into the cavity together with the molten resin in the next cycle.

[0007] If the molding speed is slow, there is no problem since the resin chips are melted in the molten resin and solidified after disappearing. However, if the molding speed is to be increased, the resin chips may remain without being melted, and there is a possibility that foreign matter that is weakly bonded to the surrounding resin in the molded product. If there is a foreign substance in a portion that may come into contact with the chemical solution, it is a problem, and this must be eliminated as a defective product, and the defective rate increases. The present invention has been made in view of the above problems, and provides an injection molding die and a molding method for a synthetic resin syringe cylinder capable of obtaining a molded article having a high molding speed and a small number of defects. An object of the present invention is to provide a synthetic resin syringe cylinder.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, a first aspect of the present invention provides a fixed mold plate and a movable mold for clamping each other to form a cavity for molding a cylinder of a synthetic resin syringe. Plate, an edge-gate-type hot runner nozzle extending from the fixed-side mounting plate side to the movable mold plate to which the fixed mold plate is attached, and a cylinder molding cavity from the side of the movable mold plate-side end of the hot runner nozzle. A gate for communicating with the end of the fixed mold plate side and a cooling path arranged so as to surround the cylinder molding cavity. Things.

According to the present invention, it is possible to prevent the cavity and the hot runner nozzle from being arranged side by side with each other, that is, overlapping each other as much as possible. Therefore, it is possible to arrange the cooling path evenly and uniformly surrounding the periphery of the cylinder molding cavity. Thereby, the uniformity of the shrinkage speed of the resin in the cavity for cylinder molding can be promoted, and the warpage and the fall that occur at the time of shrinkage can be prevented. Even if the molding speed is increased, there is no risk of occurrence of the above-mentioned warping or the like, and as a result, the molding speed can be increased and the productivity can be improved.

[0010] According to a second aspect of the present invention, in the first aspect, the cylinder molding cavity is formed in a trunk molding cavity for molding a trunk for inserting a plunger and in an opening peripheral edge at a rear end of the trunk. A flange for forming a flange portion to be formed, and a cavity for forming a cylindrical projection for forming a cylindrical projection for mounting an injection needle formed at the front end of the trunk portion, wherein the gate is a flange. 2. The layout according to claim 1, which is provided in the body molding cavity near the part molding cavity, that is, fixing the cylinder molding cavity from the side of the movable mold plate side end of the hot runner nozzle. In a layout in which the gate communicates with the side of the end on the template side, if the gate is provided in the vicinity of the cylindrical projection forming cavity in the body forming cavity, the body forming Will be the gate corresponding to the front end portion of the core for defining the inner periphery of the cavity, the core by the injection pressure of the molten resin from the gate is likely to or deformed collapse. On the other hand, in the present invention, the gate can be made to correspond to a portion relatively close to the base end of the core, so that it is possible to prevent the core from falling down and to prevent the molded product from becoming uneven in thickness. .

According to a third aspect of the present invention, in the first aspect, the cylinder molding cavity is formed at a trunk molding cavity for molding a plunger insertion trunk, and at an opening peripheral edge at a rear end of the trunk. A flange for forming a flange portion to be formed, and a cavity for forming a cylindrical projection for forming a cylindrical projection for mounting an injection needle formed at the front end of the trunk portion, wherein the gate is a flange. It is characterized by being provided on the side edge of the part.

After one cycle of molding, a solidified resin chip may remain at the molten resin injection port of the hot runner nozzle, and this chip is extruded into the cavity in the next cycle to be formed in the molded product. There is a risk of becoming foreign matter. On the other hand, according to the present invention, even if the above-mentioned tip remains as a foreign substance in the cylinder of the syringe which is a molded product, there is no problem since the tip is not in the liquid medicine enclosing portion but in the flange portion. Also, since a gate is provided corresponding to the flange,
As a result of the gate being able to correspond to a portion relatively close to the base end of the core, it is possible to prevent the core from falling down, etc., and to prevent uneven thickness of the molded product.

According to a fourth aspect of the present invention, there is provided a method for molding a synthetic resin syringe cylinder using the injection molding die according to the second or third aspect, wherein a tip of a cylindrical projection of the syringe is provided. The movable shaft provided on the movable mold plate for partitioning the bottom surface of the corresponding cylindrical projection molding cavity is advanced toward the fixed mold plate after filling the molten resin into the cylindrical projection molding cavity, and the cylindrical shape is formed. The method is characterized in that the bottom surface of the projection molding cavity is positioned.

When the molten resin is charged from the side of the cavity for molding the flange portion, there is a concern that the molten resin may be poorly rotated around the cavity for molding the cylindrical projection, particularly at the front end side. Therefore, in the present invention, since the movable shaft is advanced to position the bottom surface of the cylindrical projection molding cavity after the molten resin is filled in the cylindrical projection molding cavity, the filling of the cylindrical projection molding cavity is defective. Does not occur. As a result, a syringe cylinder without defects can be obtained.

According to a fifth aspect of the present invention, there is provided a body for inserting a plunger, a cylindrical projection for mounting an injection needle on a front end of the body, and a flange on an opening peripheral edge at a rear end of the body. From the gate position corresponding to the side edge of the collar,
An object of the present invention is to provide a synthetic resin syringe cylinder formed by injection molding using an edge gate type hot runner nozzle. In the present invention, even if the solid resin chip remaining at the injection port of the hot runner nozzle remains as a foreign matter in the cylinder, which is a molded product, the solid resin chip remains at the flange portion, not at the chemical solution enclosing portion, and thus has no problem.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partially cutaway side view showing a syringe cylinder according to an embodiment of the present invention. Referring to FIG. 1, syringe cylinder 1 is entirely made of a molded product of a synthetic resin such as polypropylene, for example, and is injection-molded by an injection mold using an edge-gate type hot runner nozzle described later.

The syringe cylinder 1 has a body 2 for inserting a plunger (push) (not shown). At the front end 2a of the body 2, a cylindrical projection 3 for mounting an unshown injection needle is formed toward the front. 1 and 2
Referring to (a), an outward flange 5 having, for example, an elliptical or elliptical shape is formed on the periphery of the opening 4 at the rear end 2b of the body 2. As shown in FIG. 1 and FIG.
Has a cutout recess 6 at the side edge 5a thereof at a position farthest from the periphery of the opening 4, and a gate cutting trace 7 remains at the bottom of the cutout recess 6 as shown in FIG. are doing.

Next, an injection mold 8 for injection-molding the above-mentioned syringe cylinder 1 will be described with reference to FIG. The injection mold 8 includes a fixed mold plate 9 and a movable mold plate 10 that are clamped to each other. The fixed mold plate 9 is fixed to the fixed-side mounting plate 11. Reference numerals 12 and 13 denote holding blocks interposed between the fixed mold plate 9 and the fixed-side mounting plate 11, and are fixed to the fixed-side mounting plate 11. The holding blocks 12 and 13 hold the hot runner nozzle 14.

The hot runner nozzle 14 is mounted on the fixed side mounting plate 1.
A pair of gates G are provided extending from the first side toward the movable mold plate 10 at opposing positions on the side of the end portion 14 a of the hot runner nozzle 14 on the movable mold plate 10 side. That is, referring to FIG. 4, the hot runner nozzle 14
This is called an edge gate type, and is configured to have a gate G in a direction orthogonal to the central axis 32 of the cylindrical nozzle body 31. Inside the hot runner nozzle 14, a heater (not shown) for keeping the resin in the resin passage in a molten state is incorporated. In the present embodiment, the description will be made on the basis of two-cavity. However, one-cavity or three-or-more-cavity may be employed.

Referring to FIG. 3 again, a pair of cores 15 are fixed to the fixed mold plate 9 on both sides of the hot runner nozzle 14. PL is a parting line. The movable mold plate 10 includes a first block 10a and a second block 10b.
And a third block 10c. The movable plate 10 is fixed to the movable-side mounting plate 16, and an intermediate block 17 is interposed between the movable-type plate 10 and the movable-side mounting plate 16. The fixed mold plate 9 and the movable mold plate 10 form a cavity 18 for molding a cylinder of a synthetic resin syringe. First and second blocks 10a, 10 of movable plate 10
A cooling water pipe 19 as a cooling path is arranged in b to surround the cavity 18.

Reference numeral 51 denotes a support block for supporting a movable shaft, which will be described later. Reference numeral 52 denotes a drive mechanism for raising and lowering the movable shaft via the support block 51. Referring to FIG.
The cylinder forming cavity 18 includes a body forming cavity 20 for forming the body 2 of the syringe cylinder 1,
A flange forming cavity 21 for forming the flange, and a cylindrical protrusion forming cavity 2 for forming the cylindrical protrusion 3.
2 is included. The gate G is provided so as to be continuous with the side edge of the flange forming cavity 21 corresponding to the side edge of the flange 5 of the syringe cylinder 1.

Referring to FIGS. 4 and 5, a fixing pin 23 for defining the inner peripheral surface of the cavity 22 for forming a cylindrical projection extends from the tip end 15a of the core 15. The fixing pin 23 is inserted into a guide hole 25 formed in a movable shaft 24 for defining the bottom surface 22a of the cavity 22 for molding a cylindrical projection when the mold is clamped.
Specifically, after the mold is clamped, the cylindrical projection molding cavity 2 is formed.
When the molten resin is filled into the cylinder molding cavity 18 including the cylinder 2, as shown in FIG. The movable shaft 24 is advanced toward the fixed mold plate 9 (upward in the figure) after the cavity 22 for molding the cylindrical protrusion is sufficiently filled with the molten resin R after being retracted by a fixed amount (for example, 2 mm). And FIG.
As shown in FIG. 5, a line L1 at the tip of the movable shaft 24 is
And the bottom surface 22 of the cylindrical projection molding cavity 22.
a is positioned. By doing this,
Insufficiency of filling the molten resin into the cylindrical projection molding cavity 22 can be prevented, and as a result, it is possible to obtain a syringe cylinder 1 having no defect.

According to the present embodiment described above, the flange from the side of the end portion 14a of the hot runner nozzle 14 on the movable mold plate 10 side to the fixed mold plate 9 side of the cylinder forming cavity 18 is formed. Since the gate G is provided so as to communicate with the side portion of the molding cavity 21, the region where the cylinder molding cavity 18 and the hot runner nozzle 14 are arranged to overlap each other sideways can be reduced as much as possible. Therefore, it is possible to arrange the cooling water pipe 19 so as to uniformly and uniformly surround the periphery of the cylinder forming cavity 18. Thereby, the uniformity of the shrinkage speed of the resin in the cylinder forming cavity 18 can be promoted, and the warpage and the fall that occur during the shrinkage can be prevented. Even if the molding speed is increased, there is no risk of occurrence of the above-mentioned warping or the like, and as a result, the molding speed can be increased and the productivity can be improved.

After one cycle of molding, a chip in which the resin is solidified at the gate G portion of the hot runner nozzle 14 remains, and this chip is extruded into the cylinder molding cavity 18 in the next cycle to mold. Even if it remains as a foreign substance in the product, it remains at the side edge 5a of the flange 5 and not at the portion filled with the chemical solution, so there is no problem at all. As a result, it can contribute to an increase in the molding speed. Further, since the gate G is arranged not at the distal end side of the core 15 but at the portion near the base end of the core 15, the injection pressure is applied when the molten resin is fed to the cylinder molding cavity 18 through the gate G. Is not deformed so as to fall down, and as a result, it is preferable in that uneven thickness of the molded product can be prevented and dimensional accuracy can be ensured.

The present invention is not limited to the above embodiment. For example, in FIG. 4, the gate G is arranged in the body forming cavity 20 in the vicinity of the flange forming cavity 21. In any case, the core can be prevented from falling down, thereby preventing uneven thickness from occurring. In FIG. 4, the cylinder molding cavity 18 may be turned upside down, and the gate G may be provided corresponding to the side of the end of the body molding cavity 20 on the side of the cylindrical projection molding cavity 22. . In addition, various changes can be made within the scope of the claims of the present invention.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of a syringe cylinder made of a synthetic resin according to an embodiment of the present invention.

FIG. 2A is a schematic front view of a flange of a syringe cylinder, and FIG. 2B is a side view of the flange.

FIG. 3 is a cross-sectional view of an injection mold of the synthetic resin syringe cylinder of FIG. 1;

FIG. 4 is an enlarged view of a main part of FIG. 3;

FIG. 5 is a cross-sectional view of a main part of an injection molding die showing a state in which a movable shaft for defining a bottom surface of a cylindrical projection molding cavity is retracted when a molten resin is filled after clamping. is there.

FIG. 6 is a cross-sectional view of a main part of an injection molding die showing a state in which a movable shaft is advanced to position a bottom surface of a cylindrical projection molding cavity after filling of a molten resin is completed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Syringe cylinder 2 Body 3 Cylindrical projection 4 Opening 5 Flange 5a Side edge 6 Notch recess 7 Gate cut mark 8 Injection molding die 9 Fixed mold plate 10 Movable mold plate 14 Hot runner nozzle 14a End portion 15 Core 18 Cylinder molding cavity 19 Cooling water pipe (cooling path) 20 Trunk molding cavity 21 Flange molding cavity 22 Cylindrical projection molding cavity 22a Bottom surface G Gate

Continued on the front page (72) Inventor Haruhito Hino 41-14 Iguchi, Takubo, Shigenobu-cho, Onsen-gun, Ehime Prefecture F-term in Matsuyama Plant of Fuji Seiki Co., Ltd.

Claims (5)

[Claims] 1. A fixed mold plate and a movable mold plate which are clamped with each other to form a cavity for molding a cylinder of a synthetic resin syringe; and a fixed mold plate for attaching the fixed mold plate to a movable mold plate. An edge gate type hot runner nozzle extending toward the end; a gate extending from the side of the movable mold plate side end of the hot runner nozzle to the fixed mold plate side end of the cylinder molding cavity; and a cylinder forming cylinder. And a cooling path arranged to surround the cavity. 2. The cylinder molding cavity according to claim 1, wherein the cylinder molding cavity comprises a trunk molding cavity for molding a plunger insertion trunk, and a flange formed at an opening peripheral edge at a rear end of the trunk. A cavity for forming a cylindrical projection for forming a cylindrical projection for mounting an injection needle formed at the front end of the body portion, wherein the gate is in the vicinity of the cavity for forming a flange. An injection mold for a synthetic resin syringe cylinder, which is provided in a body molding cavity of the above. 3. The cylinder molding cavity according to claim 1, wherein the cylinder molding cavity is formed with a body molding cavity for molding a body for inserting a plunger, and a flange formed on an opening peripheral edge at a rear end of the body. A cavity for molding a cylindrical projection for forming a cylindrical projection for mounting an injection needle formed at the front end of the trunk, and the gate is provided on a side edge of the flange. A mold for injection molding of a syringe cylinder made of synthetic resin, characterized in that it is made. 4. A method for molding a synthetic resin syringe cylinder using the injection mold according to claim 2 or 3, wherein a cylindrical projection corresponding to a tip end surface of the cylindrical projection of the syringe is formed. The movable shaft provided on the movable mold plate for partitioning the bottom surface of the cavity is advanced toward the fixed mold plate after filling the molten resin into the cylindrical projection molding cavity, and the bottom surface of the cylindrical projection molding cavity is formed. A method for molding a syringe cylinder made of synthetic resin, characterized in that the cylinder is positioned. 5. A body for inserting a plunger.
It has a cylindrical projection for mounting an injection needle at the front end of the trunk and has a flange at the opening periphery of the rear end of the trunk, and is an edge gate type from a gate position corresponding to the side edge of the flange. A synthetic resin syringe cylinder formed by injection molding using a hot runner nozzle.