JPH0595718U - Injection mold - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an injection molding die capable of easily manufacturing a large number of molded articles having no quality unevenness. [Structure] The distance R from the sprue 182 provided at the center of the mold 1 to the resin injection gates of the cavities 2A, 2B, 2G, and 2H farthest away is set to R = 1, and the cavities 2A and 2
The cross-sectional area S of the extreme end of the runner communicating with B, 2G, and 2H is S = 1. At this time, since the distance R to the resin injection gates of the cavities 2C, 2D, 2E, and 2F near the sprue 182 is R = 0.5, the cavities 2C, 2D, 2
Cross-sectional area S = 2 at the extreme end of the runner communicating with E and 2F
/ 3.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to an injection molding die for molding a large number of molded products.

[0002]

[Prior Art]

 When manufacturing an elongated bottomed cylindrical container such as a vacuum blood collection tube, a cold runner is provided which is branched from at least two branch points from the nozzle of the injection molding machine to the cavity through the sprue. It is known that multiple injection molding is performed by using an injection molding die provided with a resin injection gate communicating with each cavity.

In this case, there is a problem in that the product weight and quality of the molded product molded in each cavity vary.

In order to improve this point, conventionally, for example, as described in Japanese Utility Model Laid-Open No. 1-99609, in order to make the flow to each cavity uniform in the multi-cavity molding, a signal from a resin pressure sensor is used. A multi-cavity injection molding mold has been proposed in which the resin filling amount in each cavity is made uniform by adjusting the opening of the flow control valve without changing the dimensions of the gate and runner.

[0005]

[Problems to be solved by the device]

 However, in the conventional case as described above, a resin pressure sensor and a flow rate adjusting valve are required for each cavity, the mold structure becomes complicated, the mold cost becomes high, and the flow rate depends on the signal from the pressure sensor. Since there is a delay in the operation of the regulator valve, there is no effect even if it is applied in an injection molding process where the resin injection time is short, and the flow rate regulator functions as a function to hinder the flow of the molten resin. However, there is a problem in that the quality of the molded product deteriorates due to the accumulation of particles and decomposition or deterioration.

[0006] Then, in order to grasp the phenomenon that appearance defects are likely to occur in the molded product molded from the cavity provided in the center of the mold and to basically elucidate the cause, a runner of a multi-cavity mold is used. When the flow state of the molten resin flowing inside was analyzed, the following points were found.

That is, the longer the resin flow path from the sprue to the cavity, the faster the molten resin flowing in the cold runner is cooled, and the flow velocity becomes slower.

Therefore, as shown in FIG. 16 (a), regarding the molten resin supplied from the sprue x and flowing in the cold runner y, the molten resin a, a ′ around the inner side is the outer side at the first branch point. A resin flow path that is shorter than the surrounding molten resin b, b'is formed, and the resin temperature is high and the flow velocity is fast.

Further, as shown in FIG. 16 (b), in the molten resin flowing in the runner y at the second branch point, the inward molten resins c and c ′ are the outer molten resin d. , D ', the resin flow path is formed to be shorter, and the resin temperature is higher and the flow velocity is faster. Even between the molten resin c and c ′ of the same inner circumference, the molten resin c is mainly the molten resin a of the inner circumference at the first branch point, and the molten resin c ′ is the outermost stream of the molten resin c ′ at the first branch point. Since the molten resin b around the molten resin is the main stream, the molten resin c forms a resin flow path shorter than the molten resin c ′, and the resin temperature is high and the flow velocity is fast.

Further, as shown in FIG. 16C, in the molten resin flowing in the runner y at the third branch point, the inward molten resins e and e ′ are the outward molten resin f. , F ', the resin flow path is formed to have a shorter resin temperature and a higher flow velocity. Even between the molten resin e and e ′ of the same inner circumference, the molten resin e is mainly the inner molten resin c at the second branch point, and the molten resin e ′ is the outer stream at the second branch point. Since the molten resin d around it is the main stream, the molten resin e forms a resin flow path shorter than the molten resin e ′, and the resin temperature is high and the flow velocity is fast.

As a result, as shown in FIG. 16C, the molten resin is filled into the cavity 16K communicating with the runner in which the shortest resin flow path is formed, the earliest. Then, the molten resin is sequentially filled in the order of the cavities 16L and 16O 2, 16P which are communicated with the runner in which the short resin flow path is formed.

At this time, in the molded product in the cavity 1K that is filled the earliest, so-called melody is generated due to the sink mark phenomenon in which a concave portion is generated on the surface. For example, as shown in FIG. It is likely to occur on the outer peripheral surface of the tip portion (indicated by the arrow in the figure) or on the inner peripheral surface of the tip portion of the molded product (indicated by the arrow in the figure) as shown in FIG. The so-called "mela" associated with the sink mark phenomenon occurs more severely in the molded product obtained from the cavity communicating with the runner in which the short resin flow path is formed.

Then, a resin flow path that is shorter is formed at the end portion of the runner that communicates with the resin injection gate that is located closer to the sprue. Normally, since the sprue is placed in the center of the mold, the resin note 1 gate of the cavity communicating with the runner in which the short resin flow path is formed is located near the center of the mold.

In view of the above points, the present invention solves the problems of the prior art and provides an injection molding die capable of easily manufacturing a large number of molded products having no quality unevenness. It was done as a purpose.

[0015]

[Means for Solving the Problems]

 The invention of claim 1 of the present application corresponds to the shape of the molded product to be molded between the fixed-side mold plate and the movable mold of the mold including the fixed-side mold plate, the movable mold, and the runner stripper plate. 4 or more cavities with the inner surface shape are formed, and the fixed side template is provided with cold runners branched at at least 2 or more branch points toward the resin injection gate of each cavity through the sprue. In the injection molding die in which the runner length from the sprue to the resin injection gate communicating with each cavity is approximately equal, the end of the runner communicating with the resin injection gate located near the sprue. However, it is an injection molding die whose cross-sectional area is smaller than the end portions of other runners.

The invention of claim 2 of the present application relates to a molded product to be molded between a fixed-side mold plate and a movable mold of a mold including a fixed-side mold plate, a movable mold and a runner stripper plate. Four or more cavities with an inner surface shape corresponding to the shape are formed, and a cold plate branched at at least two or more branch points toward the resin injection gate of each cavity through the sprue on the fixed side template. In a mold for injection molding in which a runner is provided and the runner length from the sprue to the resin injection gate communicating with each cavity is approximately the same, the runner communicating with the resin injection gate located near the sprue. Is a mold for injection molding in which the peripheral portion of the end portion of is made of a material having higher thermal conductivity than the peripheral portions of the end portions of other runners.

The invention according to claim 3 of the present application provides a molded product to be molded between a fixed side mold plate and a movable mold of a mold provided with a fixed side mold plate, a movable mold and a runner stripper plate. Four or more cavities with an inner surface shape corresponding to the shape are formed, and a cold plate branched at at least two or more branch points toward the resin injection gate of each cavity through the sprue on the fixed side template. In a mold for injection molding in which a runner is provided and the runner length from the sprue to the resin injection gate that communicates with each cavity is approximately the same, the runner that communicates with the resin injection gate located near the sprue. Is a mold for injection molding in which the surface roughness of the runner surface of the other end of the runner is rougher than that of the other end.

According to a fourth aspect of the present invention, there is provided a mold including a fixed-side mold plate, a movable mold, and a runner stripper plate, which is a molded product to be molded between the fixed-side mold plate and the movable mold. Four or more cavities with an inner surface shape corresponding to the shape are formed, and a cold plate branched at at least two or more branch points toward the resin injection gate of each cavity through the sprue on the fixed side template. In a mold for injection molding in which a runner is provided and the runner length from the sprue to the resin injection gate communicating with each cavity is approximately equal, the cavity that communicates with the resin injection gate located near the sprue is connected. A resin flow control member is provided at the end of the resin so that the resin flow control member is connected to the pressing member and the molten resin is filled in the cavity. The oil flow control member is placed in the end of the cavity and pressure is applied by the pressing member to prevent the end of the cavity from being filled with the molten resin. It is an injection molding mold that has a mechanism to help the molten resin to be filled.

In the present invention, examples of the molded article include a reduced pressure blood collection tube, a container, a cover, a housing, a drawer, and a box having a wall thickness of 0.5 to 2 mm and a total length of 200 mm or less.

In the present invention, as the resin, all resins used for injection molding can be used, and examples thereof include polyethylene terephthalate, polycarbonate, polyethylene, acrylonitrile-butadiene-styrene copolymer, polymethylmethacrylate, nylon, Polyoxymethylene or the like is used.

In the present invention, as the material of the mold, iron or an alloy is used, and one having a thermal conductivity of 0.05 to 0.50 cal / cm · sec · ° C is preferably used. When the thermal conductivity of the mold is less than 0.05 cal / cm · sec · ° C, it takes a long time to cool the runner and the shot time becomes long. On the contrary, 0.50 cal / cm · sec · ° C. If it exceeds, the runner will be cooled too quickly, making it difficult to fill the molten resin.

In the present invention, the surface roughness of the runner surface of the mold is preferably in the range of ∇∇ to ∇∇∇∇ according to the surface roughness standard of JIS B0601 (hereinafter abbreviated as surface roughness standard). . If the surface roughness is less than ∇∇, the appearance of the obtained molded product is likely to deteriorate, and conversely, if it exceeds ∇∇∇∇, the molten resin is sprue surface, runner surface and cavity surface. It adheres to the surface of the mold, deteriorates the moldability (fillability), and tends to become a short mold.

First, an example of the entire structure of the injection molding die according to the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway vertical sectional view showing an example of an injection molding die of the present invention. Reference numeral 1 denotes an injection molding die for manufacturing a blood collection tube which is a molded product, and includes a movable die 11 and a fixed-side die plate 12.

The movable die 11 is composed of a core 111, a receiving plate 112 and a projecting stripper plate 113. The core 111 and the receiving plate 112 may have an integrated structure.

The core 111 has a distal end portion and a central portion which are elongated cylinders, the distal end portion is a portion which forms the inner surface of a molded product to be molded, and the top portion is a hemispherical convex spherical surface. The tip portion of the core 111 may be a draft taper surface of 10/1000 or less, the outer surface of which gradually shrinks toward the top. The central portion of the core 111 is inserted into a hole 113a formed in the projecting stripper plate 113. The base end portion of the core 111 has a larger diameter than the tip end portion and the central portion, and is fitted and fixed in a hole 112a formed in the receiving plate 112. The core 111 is fixed to the movable die mounting plate 15 via a receiving plate 112.

The stationary mold plate 12 is provided with a through hole 121 that forms an outer peripheral surface of a molded product to be molded. The fixed-side template 12 is provided with a gate 122 at a position corresponding to the top of the convex spherical surface on the top of the core 111.

A runner stripper plate 18 and a runner / gate connecting plate 19 are provided between the fixed-side template 12 and the fixed-side template mounting plate 16.

The runner stripper plate 18 is provided with a runner 181 and a sprue 182. The runner / gate connecting plate 19 is provided with a runner 191 that connects the runner 181 and the gate 122.

Then, at the time of mold opening, between the core 111 and the fixed-side mold plate 12, between the core 111 and the protruding stripper plate 113, between the fixed-side mold plate 12 and the runner-gate connecting plate 19, and the runner-gate connecting plate. 19 and the runner stripper plate 18 are opened, and the pressure is released between the runner stripper plate 18 and the fixed-side template mounting plate 16 to be in a free state.

Thus, at the time of mold clamping, the outer peripheral surface of the tip portion of the core 111, the projecting stripper plate 113, and the wall surface of the through hole 121 of the stationary-side mold plate 12 form a molded product to be molded. 20 is formed. Then, the molten resin supplied through the sprue 182 and the runners 181 and 191 is injected into the cavity 20 from the gate 122 by an injection molding machine (not shown) to mold the molded product.

In the invention of claim 1 of the present application, the end portion of the runner communicating with the resin injection gate arranged near the sprue has a smaller cross-sectional area than the end portions of the other runners. The cross-sectional area of the end portion of the runner is determined as follows, for example. That is, assuming a case where a sprue is provided at the center of the die, as described with reference to FIG. 16 above, the cavity 16K disposed at a position close to the center of the die having the sprue x is provided. The resin injection gate is connected to a runner in which a shorter resin flow path is formed.

Therefore, the cross-sectional area S of the most distal end of the runner communicating with the cavity is defined as S, the distance from the center of the mold to the resin injection gate of the cavity is defined as R, and the resin injection of the cavity farthest from the center of the mold is performed. The cross-sectional area S of the most distal part of the runner communicating with the service gate is S = 1. At this time, assuming that the distance R from the center of the mold to the resin injection gate of the cavity farthest is R = 1, for example, S = 1 and R = 0. In the range of 5 or more and less than 0.7, S = 2/3, in the range of R 0.3 or more and less than 0.5, S = 1/2, and in the range of R less than 0.3, S = 1/3 And

In the above case, the cross-sectional area of the most distal end portion of the runner is adjusted for convenience. However, a runner in which a short resin flow path is formed each time the runner is branched at the branch point. The cross-sectional area may be adjusted more finely according to the degree.

Hereinafter, an example of an injection molding die according to the first aspect of the present invention will be described with reference to the drawings. FIG. 2 is a schematic diagram showing the sprue, runner, and cavity portions of an example of an injection molding die for manufacturing the thin-walled rectangular tubular container shown in FIG.

A sprue 182 is provided at the center of the die runner stripper plate 18 (see FIG. 1), and cold runners 181 are provided from the sprue 182 toward the eight cavities 2A to 2H. . The runner 181 is branched into two at the first branch point, further branched into two at the second branch point, and communicated with a resin injection gate (not shown) communicating with each cavity. ing.

The distance R = 1 from the sprue 182 provided at the center of the mold 1 to the resin injection gates of the cavities 2A, 2B, 2G, 2H that are farthest away is set to the cavities 2A, 2B, 2G, 2H. The cross-sectional area S of the most distal end of the communicating runner is S = 1.

At this time, since the distance R to the resin injection gate of the cavities 2C, 2D, 2E, 2F near the sprue 182 is R = 0.5, the runners communicating with the cavities 2C, 2D, 2E, 2F are The cross-sectional area S of the extreme end is S = 2/3. It should be noted that the cross-sectional area S of sprues other than the above is S = 1.

FIG. 4 is a schematic view showing a sprue, a runner and a cavity portion of another example of the injection molding die for manufacturing the thin-walled cylindrical container as shown in FIG.

A sprue 182 is provided at the center of the stationary mold plate of the mold 1, and cold runners 181 are provided from the sprue 182 toward the 16 cavities 4A to 4P. The runner 181 is branched into two at the first branch point, further branched into four at the second branch point, and communicated with a resin injection gate (not shown) communicating with each cavity. There is.

A distance R = 1 from the sprue 182 provided in the center of the mold 1 to the resin injection gates of the cavities 4A, 4D, 4M, 4P farthest away is set in the cavities 4A, 4D, 4M, 4P. The cross-sectional area S of the most distal end of the communicating runner is S = 1.

At this time, since the distance R to the resin injection gate of the cavities 4F, 4G, 4J, and 4K closest to the sprue 182 is R = 0.4, the runners communicating with the cavities 4F, 4G, 4J, and 4K are connected. The cross-sectional area S of the endmost portion is S = 1/2.

Further, since the distance R to the resin injection gates of the cavities 4B, 4C, 4E, 4H, 4I, 4L, 4N, and 4O next to the sprue 182 is 0.8, the cavities 4B and 4C are shown. , 4E, 4H, 4I, 4L, 4N, 4O, the cross-sectional area of the end of the runner is S = 1. The cross-sectional area S of runners other than the above is S = 1.

FIG. 6 is a schematic diagram showing the sprue, runner, and cavity portions of another example of the injection molding die for manufacturing the thin-walled cylindrical container as shown in FIG.

A sprue 182 is provided at the center of the stationary mold plate of the mold 1, and cold runners 181 are provided from the sprue 182 toward the 16 cavities 6A to 6P. The runner 181 is branched into two at the first branch point, further divided into two at the second branch point, and further divided into two at the third branch point, to each cavity. It is communicated with a resin injection gate (not shown) communicating therewith.

The distance R = 1 from the sprue 182 provided at the center of the mold 1 to the resin injection gates of the cavities 6A, 6D, 6M, 6P that are farthest away is set to the cavities 6A, 6D, 6M, 6P. The cross-sectional area S of the most distal end of the communicating runner is S = 1.

At this time, since the distance R to the resin injection gate of the cavities 6F, 6G, 6J, 6K closest to the sprue 182 is R = 0.50, the runners communicating with the cavities 6F, 6G, 6J, 6K. The cross-sectional area S of the outermost portion of S is set to S = 2/3.

Further, since the distance R to the resin injection gate of the cavities 6B, 6C, 6E, 6H, 6I, 6L, 6N and 6O next to the sprue 182 is R = 0.79, the cavities 6B and 6C are , 6E, 6H, 6I, 6L, 6N, 6O, the cross-sectional area S of the end of the runner is S = 1. The cross-sectional area S of runners other than the above is S = 1.

FIG. 8 is a schematic diagram showing the sprue, runner, and cavity portions of an example of an injection-molding injection-molding die for manufacturing the thin-walled cylindrical container as shown in FIG.

A sprue 182 is provided at the center of the stationary mold plate of the mold 1, and a cold runner 181 is provided from the nozzle of the injection molding machine through the sprue 182 toward the 24 cavities 8A to 8X. There is. The runner 181 is branched into two at the first branch point, further branched into two at the second branch point, further branched into three at the third branch point, and communicated with each cavity. A resin injection gate (not shown) is provided.

The distance R = 1 from the sprue 182 provided in the center of the mold 1 to the resin injection gates of the cavities 8A, 8D, 8U, 8X farthest away is set to the cavities 8A, 8D, 8U, 8X. The cross-sectional area S of the most distal end of the communicating runner is S = 1.

At this time, since the distance R = 0.39 to the resin injection gate of the cavity 8J, 8K, 8N, 8O closest to the sprue 182, the cavities 8J, 8K, 8N, 8O near the sprue 182 are located. The cross-sectional area S of the outermost end of the runner communicating with is S = 1/2.

Further, since the cavities 8F, 8G, 8I, 8L, 8M, 8P, 8R and 8S next to the sprue 182 have a distance R to the resin injection gate R = 0.61, the cavities 8F and 8G , 8I, 8L, 8M, 8P, 8R, 8S, the cross-sectional area S of the end of the runner S = 2/3.

Further, since the distance R to the resin injection gate of the cavities 8E, 8H, 8Q, 8T closest to the sprue 182 is R = 0.78, the runners communicating with the cavities 8E, 8H, 8Q, 8T are The cross-sectional area S of the extreme end is S = 1.

Further, since the distance R to the resin injection gate of the cavities 8B, 8C, 8V, 8W next to the sprue 182 is R = 0.87, the runners communicating with the cavities 8B, 8C, 8V, 8W are The cross-sectional area S of the extreme end is S = 1. The cross-sectional area S of runners other than the above is S = 1.

In the invention of claim 2 of the present application, the peripheral portion of the end portion of the runner communicating with the resin injection gate arranged at the position close to the sprue has a higher thermal conductivity than the end portions of other runners. Is a high quality material.

The portion made of a material having a high thermal conductivity is formed, for example, in a die body by a nesting method. A seal rubber or the like may be interposed between the mold body and the insert made of a material having a high thermal conductivity in order to prevent heat conduction therebetween.

In the present invention, a material having a thermal conductivity of 0.05 to 0.50 cal / cm · sec · ° C. is preferably used for the mold, and within this range, the heat transfer of the mold body is performed. The ratio of the thermal conductivity of the portion made of a material having a high thermal conductivity to the conductivity is preferably 1.5 to 10. If this ratio is less than 1.5, so-called mella due to the sink phenomenon is likely to occur in the molded product obtained from the cavity communicating with the runner in which a short resin flow path is formed. However, the strength of the mold is reduced, and durability is likely to be a problem.

The material of the peripheral portion of the end portion of the mold runner is determined, for example, as follows. That is, assuming a case where a sprue is provided in the center of the mold, as described with reference to FIG. 16 above, resin injection into a cavity connected to a runner in which a shorter resin flow path is formed is formed from the sprue. The gate is located closer to the center of the mold with the sprue.

Therefore, when the distance from the center of the mold to the resin injection gate of the cavity is R and the distance from the center of the mold to the resin injection gate of the cavity is R = 1, for example, R The mold material around the outermost end of the runner that communicates with the cavity within a range of less than 0.7 has a higher thermal conductivity than the mold material around the runner that communicates with the cavity farthest from the mold center. Use a material with a high rate. Also, when R is 0. The mold material of the outermost peripheral part of the runner communicating with the cavity within the range of 7 or more is the same as the mold material of the peripheral part of the runner communicating with the cavity farthest from the mold center.

As described with reference to FIG. 16 described above, the shortest resin flow path is formed in FIG. 16 from the sprue 182 to the cavity 16K via the flow path of ace. It is a thing. The mold material around the portion corresponding to the runner surface facing the flow path of ac may be a material having high thermal conductivity.

Hereinafter, an example of an injection molding die according to the second aspect of the present invention will be described with reference to the drawings. FIG. 10 is a schematic diagram showing a sprue, a runner, and a cavity portion of an example of an injection molding die for manufacturing the thin rectangular plate shown in FIG.

A sprue 182 is provided at the center of the stationary mold plate of the mold 1, and runners 181 are provided from the sprue 182 toward the 16 cavities 10A to 10P. The runner 181 is branched into two at a first branch point, is branched into two at a second branch point, and is communicated with a resin injection gate (not shown) communicating with each cavity. There is.

The distance R from the sprue 182 provided in the center of the mold 1 to the resin injection gates of the cavities 10A, 10D, 10M and 10P farthest from each other is set to communicate with the cavities 10A, 10D, 10M and 10P. The mold material around the runner is a material with low thermal conductivity.

At this time, since the distance R to the resin injection gate of the cavity 10F, 10G, 10J, 10K closest to the sprue 182 is R = 0.50, the runners communicating with the cavity 10F, 10G, 10J, 10K are A nest 30 made of a material having a high thermal conductivity is provided around the outermost end.

In this case, in order to exert more effect, a nest made of a material having a high thermal conductivity is also formed around the portion corresponding to the runner surface facing the flow path ac in FIG. 30 is provided as an extension.

Further, the distance R to the resin injection gates of the cavities 10B, 10C, 10E, 10H, 10I, 10L, 10N, and 10O next to the sprue 182 is R = 0.79, so that the cavities 10B, 10C, and 10E. , 10H, 10I, 10L, 10N, and 10O, the mold material around the outermost end of the runner communicating with 10H, 10I, 10L, 10N, and 10O has a low thermal conductivity. In addition, the mold material around the runner other than the above is a material having low thermal conductivity.

In the invention of claim 3 of the present application, the runner end portion, which communicates with the resin injection gate disposed near the sprue, has a surface roughness of the runner surface more than that of the other runner end portions. It's easy.

In the present invention, the surface roughness of the runner surface of the mold is preferably in the range of ∇∇ to ∇∇∇∇. Among them, it is connected to the resin injection gate located near the sprue. The surface roughness of the runner surface at the end of the runner is rough, and the range is preferably ∇∇ to ∇∇∇.

The surface roughness of the runner surface at the end of the runner is determined, for example, as follows. That is, assuming that a sprue is provided at the center of the mold, as described with reference to FIG. 16 above, the resin of the cavity communicated with the runner in which a shorter resin flow path is formed from the sprue to the cavity is formed. The injection gate is located closer to the center of the mold with the sprue.

Therefore, when the distance from the center of the mold to the resin injection gate of the cavity is R and the distance from the center of the mold to the resin injection gate of the cavity is R = 1, for example, R The surface roughness of the runner surface at the most distal end of the runner communicating with the cavity within a range of less than 0.7 is rougher than the surface roughness of the runner surface of the runner communicating with the cavity farthest from the mold center. In addition, the runner surface at the extreme end of the runner that communicates with the cavity where R is 0.7 or more is the same as the runner surface of the runner that communicates with the cavity farthest from the mold center.

Hereinafter, an example of an injection molding die according to the third aspect of the present invention will be described with reference to the drawings. FIG. 12 is a schematic view showing a sprue, a runner, and a cavity portion of an example of an injection-molding injection-molding die for manufacturing a thin-walled rectangular tubular container similar to that shown in FIG.

A fixed side mold plate of the mold 1 is provided with a sprue 182 at the center, and runners 181 are provided from the sprue 182 toward the eight cavities 12A to 12H. The runner 181 is branched into two at a first branch point, is branched into two at a second branch point, and is communicated with a resin injection gate (not shown) communicating with each cavity. ..

A distance R = 1 from the sprue 182 provided at the center of the mold 1 to the resin injection gates of the cavities 12A, 12B, 12G, and 12H farthest from each other is communicated with the cavities 12A, 12B, 12G, and 12H. The surface roughness of the runner surface at the extreme end of the runner is ∇∇∇.

At this time, since the distance R to the resin injection gates of the cavities 12C, 12D, 12E, and 12F near the sprue 182 is 0.5, the runners communicating with the cavities 12C, 12D, 12E, and 12F are the maximum. The surface roughness of the end runner surface is ∇∇. The surface roughness of the runner surface other than the above is ∇∇∇.

FIG. 13 shows another injection molding injection mold for manufacturing a thin-walled cylindrical container (outer diameter 20 mm, length 100 mm, wall thickness 1.3 mm) similar to that shown in FIG. It is a schematic diagram which shows the part of a sprue, a runner, and a cavity of an example.

A sprue 182 is provided at the center of the stationary mold plate of the mold 1, and runners 181 are provided from the sprue 182 toward the 16 cavities 13A to 13P. The runner 181 is branched into two at a first branching point, is branched into four at a second branching point, and is communicated with a resin injection gate (not shown) communicating with each cavity.

The distance R = 1 from the sprue 182 provided at the center of the mold 1 to the resin injection gates of the cavities 13A, 13D, 13M, and 13P farthest from each other is communicated with the cavities 13A, 13D, 13M, and 13P. The surface roughness of the runner surface at the extreme end of the runner is ∇∇∇∇.

At this time, since the distance R to the resin injection gate of the cavities 13F, 13G, 13J, 13K closest to the sprue 182 is R = 0.4, the runners communicating with the cavities 13F, 13G, 13J, 13K are The surface roughness of the runner surface at the extreme end is ∇∇∇.

Further, since the distance R to the resin injection gates of the cavities 13B, 13C, 13E, 13H, 13I, 13L, 13N, 13O next to the sprue 182 is 0.8, the cavities 13B, 13C, The surface roughness of the runner surface of the runner communicating with 13E, 13H, 13I, 13L, 13N, and 13O is ∇∇∇∇. In addition, the surface roughness of the runner surface of runners other than the above is ∇∇∇∇.

FIG. 14 is a schematic diagram showing the sprue, runner, and cavity portions of another example of the injection molding die for manufacturing the thin-walled cylindrical container as shown in FIG.

The mold plate on the fixed side of the mold 1 is provided with a sprue 182 at the center, and runners 181 are provided from the sprue 182 toward the 16 cavities 14A to 14P. The runner 181 is branched into two at the first branching point, two at the second branching point, two at the third branching point, and two at the third branching point to inject resin into each cavity. It is connected to a gate (not shown).

The distance R = 1 from the sprue 182 provided at the center of the mold 1 to the resin injection gates of the cavities 14A, 14D, 14M, and 14P farthest from each other is communicated with the cavities 14A, 14D, 14M, and 14P. Let the surface roughness of the runner surface of the runner be ∇∇∇∇.

At this time, since the distance R to the resin injection gate of the cavity 14F, 14G, 14J, 14K closest to the sprue 182 is R = 0.34, the runners communicating with the cavity 14F, 14G, 14J, 14K are The surface roughness of the runner surface at the extreme end is ∇∇.

Since the distance R to the resin injection gates of the cavities 14B, 14C, 14E, 14H, 14I, 14L, 14N, 14O next to the sprue 182 is R = 0.73, the cavities 14B, 14C, 14E are , 14H, 14I, 14L, 14N, 14O is defined as ∇∇∇∇. The surface roughness of the runner surface of runners other than the above is ∇∇∇∇.

According to the invention of claim 4 of the present application, a resin flow control member is provided in a distal end of a cavity communicating with a resin injection gate disposed near the sprue, and the resin flow control member is provided. When the member is connected to the pressing member and the cavity is filled with the molten resin, the resin flow control member is kept inside the end of the cavity and pressure is applied by the pressing member, and the cavity is closed. It is said to be a mechanism that helps the molten resin to fill the other end while preventing the molten resin from filling the inner end.

Hereinafter, the injection molding die of the invention of claim 4 of the present application will be described with reference to the drawings. FIG. 15A shows an example of the mold of the present invention. In the cavity where a short resin flow path is formed from the sprue to the cavity, that is, in the end of the cavity 20 communicating with the resin injection gate located near the sprue, the outer surface shape corresponding to the inner surface shape of the end portion of the cavity is formed. The resin flow control member 113b having the above is provided so as to be freely inserted and withdrawn.

A pressing member 113c composed of a hydraulic cylinder is connected to the resin flow control member 113b via a receiving plate 113a, and the pressing member 113c is fixed to the projecting stripper plate 113. The pressing member 113c can apply pressure to the resin flow control member 113b.

A pressure of 5 to ²⁰ kg / cm ² is applied to the resin flow control member 113b by the pressing member 113c.

Although a pneumatic cylinder or a spring may be used instead of the hydraulic cylinder, a hydraulic cylinder or a pneumatic cylinder is preferably used. ..

The material of the resin flow control member 113b can be appropriately used as long as it is a material for a mold, but it is preferable that the hardness is higher than the material of the mold body.

The gap between the inner peripheral surface of the end portion of the cavity and the outer peripheral surface of the resin flow control member 113b is preferably in the range of 10 to 30 μm. When it is less than 10 μm, the inner peripheral surface of the cavity end portion or the outer peripheral surface of the resin flow control member 113b is easily scratched, and when it exceeds 30 μm, on the contrary, the inner peripheral surface of the cavity end portion, Molten resin easily enters between the resin flow control member 113b and the outer peripheral surface thereof.

Then, as shown in FIG. 15 (a), the resin flow control member 113b is inserted into the end of the cavity 20 connected to the runner in which the short resin path is formed, and the resin flow control member 113b has a short resin flow path in its cavity. When the molten resin that has been supplied via the press is about to be filled, the tip of the molten resin is pressed while the pressure is applied by the pressing member 113c to help the molten resin fill the other cavity. The resin flow control member 113b is pressed until the molten resin is uniformly filled in the cavity.

The pressure applied to the resin flow control member 113b may be lower than the resin pressure or higher than the resin pressure. When the pressure applied to the resin flow control member 113b is less than the resin pressure, the resin flow control member 113b retreats due to the pressure of the resin, but during this time, the molten resin easily flows to other cavities. When the pressure applied to the resin flow control member 113b is equal to or higher than that of the resin, the resin flow control member 113b is stopped at the position extended by the pressing member 113c, and during this time, the molten resin is made to flow easily in other cavities.

After that, the pressure is released, and as shown in FIG. 15B, the front end surface of the resin flow control member 113b retracts to the end edge of the cavity 20, and the filling of the molten resin into the cavity 20 is completed. To do. At this time, the filling of the molten resin is simultaneously completed in the other cavities.

The cavity in which the resin flow control member 113b is provided is determined as follows, for example. That is, assuming a case where a sprue is provided at the center of the mold, as described with reference to FIG. 1 above, the cavity of the cavity connected to the runner in which a shorter resin channel is formed from the sprue to the cavity is formed. The resin injection gate is located closer to the center of the mold provided with the sprue.

Therefore, when the distance from the center of the mold to the resin injection gate of the cavity is R, and the distance from the center of the mold to the resin injection gate of the cavity is R = 1, for example, R The resin flow control member 113b is provided in the end of the cavity within the range of less than 0.7.

An example of an injection molding die for manufacturing a thin-walled rectangular tubular container having the same arrangement of sprue, runners, and cavities as shown in FIG. 12 and being similar to that shown in FIG. 3 will be described. To do. The distance R from the sprue 182 provided in the center of the mold 1 to the resin injection gates of the cavities 12A, 12B, 12G, and 12H that are the furthest away is R = 1. The resin flow control member 113b is not provided in the cavities 12A, 12B, 12G and 12H.

At this time, since the distance R to the resin injection gate of the cavities 12C, 12D, 12E, 12F near the sprue 182 is R = 0.5, the resin flow into the ends of the cavities 12C, 12D, 12E, 12F. A control member 113b is provided.

Another example of an injection-molding injection-molding die having the same arrangement of sprue, runners, and cavities as shown in FIG. 13 for producing a thin-walled cylindrical container similar to that shown in FIG. 5 will be described. To do.

The distance R = 1 from the sprue 182 provided in the center of the mold 1 to the resin injection gates of the cavities 13A, 13D, 13M, and 13P farthest away. The resin flow control member 113b is not provided in the cavities 13A, 13D, 13M, 13P.

At this time, since the distance R to the resin injecting gate of the cavities 13F, 13G, 13J, and 13K closest to the sprue 182 is R = 0.4, the resin is placed in the ends of the cavities 13F, 13G, 13J, and 13K. A flow control member 113b is provided.

Further, since the distance R to the resin injection gates of the cavities 13B, 13C, 13E, 13H, 13I, 13L, 13N, 13O next to the sprue 182 is 0.8, the cavities 13B, 13C, The resin flow control member 113b is not provided in 13E, 13H, 13I, 13L, 13N, and 13O.

Another example of an injection molding mold for producing a thin cylindrical container similar to that shown in FIG. 7 with a sprue, runner and cavity arrangement similar to that shown in FIG. explain.

The mold plate on the fixed side of the mold 1 is provided with a sprue 182 at the center, and runners 181 are provided from the sprue 182 toward the 16 cavities 14A to 14P. The runner 181 is branched into two at a first branching point, is branched into four at a second branching point, and is communicated with a resin injection gate (not shown) communicating with each cavity.

The distance R = 1 from the sprue 182 provided in the center of the mold 1 to the resin injection gates of the cavities 14A, 14D, 14M, and 14P that are the furthest away. The resin flow control member 113b is not provided in the cavities 14A, 14D, 14M and 14P.

At this time, since the distance R to the resin injection gate of the cavities 14F, 14G, 14J, 14K closest to the sprue 182 is R = 0.4, the resin is filled in the ends of the cavities 14F, 14G, 14J, 14K. A flow control member 113b is provided.

Further, since the distance R to the resin injection gates of the cavities 14B, 14C, 14E, 14H, 14I, 14L, 14N, 14O next to the sprue 182 is 0.8, the cavities 14B, 14C, The resin flow control member 113b is not provided in 14E, 14H, 14I, 14L, 14N, and 14O.

[0109]

[Action]

 In the inventions of claims 1 to 3 of the present application, is the cross-sectional area of the end portion of the runner communicating with the resin injection gate located near the sprue smaller than that of the other runner end portions? , The peripheral part of the end of the runner communicating with the resin injection gate located near the sprue is made of a material having a higher thermal conductivity than the peripheral part of the end of another runner, or , The runner end that communicates with the resin injection gate located near the sprue has a rougher surface on the runner surface than the other runner end, so it is located closer to the sprue. The molten resin is not filled as early as in the cavity communicating with the resin injection gate, and the timing of filling the molten resin in each cavity becomes uniform. In addition, it is possible to easily manufacture a number of thin-walled molded products with uniform quality, and the modification of this mold requires only changing the cross-sectional area of the runner of the runner stopper plate. It is easy to modify and the cost of modification is cheap.

According to the invention of claim 4 of the present application, the resin flow control member is provided so as to be able to enter and exit in the end of the cavity that communicates with the resin injection gate arranged at a position close to the sprue. When the member is connected to the pressing member and the cavity is filled with the molten resin, the resin flow control member is kept inside the end of the cavity and pressure is applied by the pressing member, and the cavity is closed. The resin injection gate is located near the sprue because it has a mechanism to prevent the molten resin from filling the end of the inside while filling the molten resin into other cavities. The molten resin is not filled as quickly as in the cavity communicating with the cavity, and the timing of filling the molten resin in each cavity is uniform, so a thin-walled molded product with uniform quality can be obtained. It can be easily manufactured by taking many pieces.

[0111]

【Example】

Example 1 Using a mold shown in FIG. 2, a 100-ton injection molding machine manufactured by Toshiba Machine Co., Ltd., polycarbonate (PC) (made by Teijin Chemicals: trade name “L-1250”) was used as a resin, and injection pressure was used. Under a molding condition of 1200 kg / cm ² , mold temperature of 80 ° C., resin temperature of 295 ° C., and injection time of 1.8 seconds, a thin rectangular container (outer diameter 20 mm, length 40 mm, wall thickness) as shown in FIG. 8 mm (2 mm) was manufactured. As a result, the appearance of the thin-walled rectangular tubular container obtained from the eight cavities was good.

Comparative Example 1 Using the same mold as that shown in FIG. 2 except that the cross-sectional area S = 1 of the entire runner was used, in the same manner as in Example 1, eight thin-walled rectangular containers were manufactured. went. As a result, the appearance of the thin-walled rectangular cylindrical container obtained from the eight cavities is the same as that of the thin-walled rectangular cylindrical container obtained from the cavities corresponding to the cavities 2C, 2D, 2E, and 2F closest to the sprue 182. Was observed. It should be noted that no sink mark was observed on the surface of the thin-walled rectangular tubular container obtained from other cavities.

Example 2 Using a mold shown in FIG. 4, a J-220E injection molding machine manufactured by Japan Steel Works, Ltd. was used, and polyethylene terephthalate (PET) as a resin (manufactured by Mitsui Petrochemical Co., Ltd .: trade name “Pet J”). --001 "), injection pressure 1400 kg / cm ² , mold temperature 15 ° C., resin temperature 305 ° C., injection time 2.5 seconds under the molding conditions of a thin cylindrical container (outer diameter 20 mm) as shown in FIG. , Length 100 mm, wall thickness 1.5 mm) were produced. As a result, the appearances of the thin-walled cylindrical containers obtained from the 16 cavities were all good.

Comparative Example 2 16 thin-walled cylindrical containers were manufactured in the same manner as in Example 2 except that the same die as that shown in FIG. It was As a result, the appearance of the thin-walled cylindrical container obtained from the 16 cavities is the same as that of the thin-walled cylindrical container obtained from the cavities corresponding to the cavities 4F, 4G, 4J, and 4K closest to the sprue 182. Was observed. It should be noted that no sink mark was found on the surface of the thin-walled cylindrical container obtained from other cavities.

Example 3 Using the mold shown in FIG. 8, a J-150E injection molding machine manufactured by Japan Steel Works, Ltd. was used, and PET (manufactured by Mitsubishi Rayon Co., Ltd .: trade name “MA580”) was used as a resin, and an injection pressure of 1 was used. Under the molding conditions of 300 kg / cm ² , mold temperature 15 ° C., resin temperature 295 ° C., and injection time 3.0 seconds, a thin cylindrical container (outer diameter 16 mm, length 75 mm, wall thickness 1. (3 mm) 24 pieces were manufactured. As a result, the appearances of the thin-walled cylindrical containers obtained from the 24 cavities were all good.

Comparative Example 3 Using the same die as shown in FIG. 8 except that the cross-sectional area S = 1 of the entire runner was used, 24 thin-walled cylindrical containers were manufactured in the same manner as in Example 3. It was As a result, the appearance of the thin-walled cylindrical container obtained from the 24 cavities is the same as that of the thin-walled cylindrical container obtained from the cavities corresponding to the cavities 8J, 8K, 8N, and 8O closest to the sprue 182. Was observed. It should be noted that no sink mark was found on the surface of the thin-walled cylindrical container obtained from other cavities.

Example 4 The mold body was made of a material (SUS 420) having a thermal conductivity of 0.05 cal / cm · sec · ° C., and the mold part 30 having a high thermal conductivity had a thermal conductivity of 0.31 cal l. Using a mold shown in FIG. 10 made of a material having a temperature of / cm · sec · ° C (Kobe Steel Co., Ltd .: trade name “HR750”) and using J-150E manufactured by Japan Steel Works, PET (Kodak) as a resin. Manufactured by the company: product name “CODACK7352”), injection pressure 1600 kg / cm ² , mold temperature 15 ° C., resin temperature 300 ° C., injection time 2. Under the molding condition of 4 seconds, 16 thin plates (width 20 mm, length 50 mm, wall thickness 3 mm) as shown in FIG. 13 were manufactured. With respect to the thin plate obtained from 16 cavities, the amount of sink marks at the central portion with the most sinks was measured according to JIS B0601. The results are shown in Table 1. The amount of sink mark is indicated by the maximum height Rmax.

Example 5 A mold portion 30 having a high thermal conductivity is made of a material having a thermal conductivity of 0.14 cal / cm · sec · ° C. (Kobe Steel Co., Ltd .: trade name “HR30P”) and is shown in FIG. In the same manner as in Example 4 except that the same die as that used in Example 4 was used, 16 thin-walled plates similar to Example 4 were taken. With respect to the thin plate obtained from 16 cavities, the amount of sink was measured in the same manner as in Example 4. The results are shown in Table 1.

Example 6 A mold part 30 having a high thermal conductivity is made of a material having a thermal conductivity of 0.11 cal / cm · sec · ° C. (Kobe Steel Co., Ltd .: trade name “HR40P”). Except for the above, 16 thin plates similar to those in Example 4 were prepared in the same manner as in Example 4. With respect to the thin plate obtained from 16 cavities, the amount of sink was measured in the same manner as in Example 4. The results are shown in Table 1.

Comparative Example 4 Instead of the mold part 30 having a high thermal conductivity, a material having a thermal conductivity of 0.06 cal / cm · sec · ° C. (Kobe Steel Co., Ltd .: trade name “KSTM420”) was used. Sixteen thin plates similar to those in Example 4 were taken in the same manner as in Example 4 except that a mold composed of mold parts was used. With respect to the thin plate obtained from 16 cavities, the amount of sink was measured in the same manner as in Example 4. The results are shown in Table 1.

[0121]

[Table 1]

Example 7 The surface roughness of the runner surface at the extreme end of the runner communicating with the cavities 12C, 12D, 12E, 12F is ∇∇∇, and the surface roughness of the runner surfaces of the other runners is ∇∇∇∇. 12, using a 100-ton injection molding machine manufactured by Toshiba Machine Co., Ltd., using PC (manufactured by Teijin Kasei: trade name "L-1250") as a resin, injection pressure 1200 kg / cm ² , Mold temperature 15 ° C, resin temperature 290 ° C, injection time 0. Under a molding condition of 7 seconds, eight thin-walled rectangular tubular containers (outer diameter 20 mm, length 40 mm, wall thickness 2 mm) as shown in FIG. 3 were manufactured. As a result, the appearance of the thin-walled rectangular tubular container obtained from the eight cavities was good.

Comparative Example 5 As shown in FIG. 5, in the same manner as in Example 7 except that the mold corresponding to FIG. 12 in which the surface roughness of the runner surfaces of all the runners was ∇∇∇∇ was used. Eight similar thin-walled rectangular tubular containers were manufactured. As a result, the appearance of the thin-walled rectangular cylindrical container obtained from the eight cavities is similar to that of the thin-walled rectangular cylindrical container obtained from the cavities corresponding to the cavities 12C, 12D, 12E, and 12F closest to the sprue 182. Occurrence of sink marks was observed. It should be noted that no sink mark was found on the surface of the thin-walled rectangular tubular container obtained from the other cavities.

Example 8 The surface roughness of the runner surface at the extreme end of the runner communicating with the cavities 13F, 13G, 13J and 13K is ∇∇, and the surface roughness of the runner surfaces of the other runners is ∇∇∇∇. Using a certain mold shown in FIG. 13, a J-150E injection molding machine manufactured by Japan Steel Works, Ltd., using PET (made by Mitsubishi Rayon Co., Ltd .: trade name “MA580”) as a resin, injection pressure 1200 kg / cm ² , metal Sixteen thin-walled cylindrical containers (outer diameter 20 mm, length 100 mm, wall thickness 1.3 mm) as shown in FIG. 5 under molding conditions of mold temperature 15 ° C., resin temperature 290 ° C., and injection time 1.5 seconds. It was manufactured. As a result, the appearances of the thin-walled cylindrical containers obtained from the 16 cavities were all good.

Comparative Example 6 As shown in FIG. 8, in the same manner as in Example 1 except that the mold corresponding to FIG. 13 in which the surface roughness of the runner surfaces of all the runners was ∇∇∇∇ was used. Sixteen thin-walled cylindrical containers were manufactured in the same manner. As a result, the appearance of the thin-walled cylindrical container obtained from the 16 cavities is the same as that of the thin-walled cylindrical container obtained from the cavities corresponding to the cavities 13F, 13G, 13J, and 13K closest to the sprue 182. Was observed. No sink marks were found on the surface of the thin-walled cylindrical container obtained from the other cavities.

Example 9 The surface roughness of the runner surface at the extreme end of the runner communicating with the cavities 14F, 14G, 14J and 14K was ∇∇, and the surface roughness of the runner surfaces of the other runners was ∇∇∇∇. Using a certain mold shown in FIG. 14, using a J-220E injection molding machine manufactured by Japan Steel Works, using PET (Mitsui Petrochemical Co., Ltd .: trade name “PET J001”) as a resin, injection pressure 1300 kg / cm ² 16 molds of thin-walled cylindrical container (outer diameter 25 mm, length 75 mm, wall thickness 1.5 mm) as shown in FIG. 7 under molding conditions of mold temperature 15 ° C., resin temperature 300 ° C., and injection time 1 second. It was manufactured. As a result, the appearances of the thin-walled cylindrical containers obtained from the 16 cavities were all good.

Comparative Example 7 Thin wall similar to Example 9 in the same manner as in Example 9 except that a mold corresponding to FIG. 14 in which the surface roughness of the runner surfaces of all runners was ∇∇∇∇ was used. 16 cylindrical containers were manufactured. As a result, the appearance of the thin-walled rectangular container obtained from the 16 cavities is similar to that of the thin-walled cylindrical container obtained from the cavities corresponding to the cavities 14F, 14G, 14J, and 14K closest to the sprue 182. Occurrence of sink marks was observed. No sink mark was found on the surface of the thin-walled cylindrical container obtained from the other cavities.

Embodiment 10 A resin flow rate adjusting member 113b as shown in FIG. 15 is provided in the ends of the cavities 12C, 12D, 12E and 12F arranged in the central portion, and the resin flow rate adjusting members are provided in the ends of the other cavities. Using a mold with the sprue, runner, and cavity arrangement similar to that shown in FIG. 12 without the 113b, a J-100 J injection molding machine manufactured by Japan Steel Works was used, and PET (Mitsubishi Rayon Co., Ltd .: trade name " MA580 "), an ejection pressure of 1200 kg / cm ² , a mold temperature of 15 ° C, a resin temperature of 290 ° C, and an injection time of 0. Under a molding condition of 7 seconds, a pressure of 4 kg / cm ² was applied to the resin flow rate control member by a pressing member for 0.7 seconds from the start of injection, and then 0, and a thin rectangular cylindrical container (outer diameter Eight pieces of 20 mm, a length of 40 mm, and a wall thickness of 2 mm were manufactured. As a result, the appearance of the thin-walled rectangular tubular container obtained from the eight cavities was good.

Comparative Example 8 Eight thin-walled rectangular tubular containers similar to those of Example 10 were manufactured in the same manner as in Example 10 except that the resin flow rate adjusting members 113b were not provided in the ends of all the cavities. I made it. As a result, the appearance of the thin-walled rectangular cylindrical container obtained from the eight cavities is similar to that of the thin-walled rectangular cylindrical container obtained from the cavities corresponding to the cavities 12C, 12D, 12E, and 12F closest to the sprue 182. Occurrence of sink marks was observed. It should be noted that no sink mark was found on the surface of the thin-walled rectangular tubular container obtained from the other cavities.

Example 11 A resin flow rate adjusting member 113b as shown in FIG. 15 is provided in the ends of the cavities 13F, 13G, 13J and 13K arranged in the central portion, and the resin flow rate adjusting members are provided in the ends of the other cavities. Using a mold with the sprue, runner, and cavity arrangement similar to that shown in FIG. 13 without 113b, a 150-ton injection molding machine manufactured by Toshiba Machine Co., Ltd. was used, and PET (manufactured by Teijin Ltd .: trade name “L1250”) was used as the resin. The injection pressure is 1200 kg / cm ² , the mold temperature is 100 ° C., the resin temperature is 290 ° C., the injection time is 1.5 seconds, and the pressure of the resin flow rate adjusting member is 7 kg / cm ² for 1.5 seconds from the start of injection by the pressing member. Under the molding conditions of 0 after the application, 16 thin-walled cylindrical containers (outer diameter 20 mm, length 100 mm, wall thickness 1.3 mm) as shown in FIG. 5 were manufactured. As a result, the appearances of the thin-walled cylindrical containers obtained from the 16 cavities were all good.

Comparative Example 9 16 thin-walled cylindrical containers similar to those in Example 11 were produced in the same manner as in Example 11 except that the resin flow rate adjusting member 113b was not provided in the ends of all the cavities. went. As a result, the appearance of the thin-walled cylindrical container obtained from the 16 cavities is the same as that of the thin-walled cylindrical container obtained from the cavities corresponding to the cavities 13F, 13G, 13J, and 13K closest to the sprue 182. Was observed. No sink mark was found on the surface of the thin-walled cylindrical container obtained from the other cavities.

Example 12 A resin flow rate adjusting member 113b as shown in FIG. 15 is provided in the ends of the cavities 14F, 14G, 14J and 14K arranged at the center, and resin flow rate adjusting members are provided in the ends of the other cavities. Using a mold with a sprue, runner, and cavity arrangement similar to that of FIG. 14 without the 113b, a J-150E injection molding machine manufactured by Japan Steel Works, Ltd. was used, and PET (Kodak: trade name "9921" was used as the resin. )), An injection pressure of 1300 kg / cm ² , a mold temperature of 15 ° C., a resin temperature of 300 ° C., an injection time of 1 second, and a pressure of 5 kg / cm ² for 1 second from the start of injection by the pressing member on the resin flow rate adjusting member. Sixteen thin-walled cylindrical containers (outer diameter 25 mm, length 75 mm, wall thickness 1.5 mm) as shown in FIG. As a result, the appearances of the thin-walled cylindrical containers obtained from the 16 cavities were all good.

Comparative Example 10 16 thin-walled rectangular cylindrical containers similar to those in Example 12 were manufactured in the same manner as in Example 12 except that the resin flow rate adjusting member 113b was not provided in the ends of all the cavities. I went. As a result, the appearance of the thin-walled rectangular container obtained from the 16 cavities is similar to that of the thin-walled cylindrical container obtained from the cavities corresponding to the cavities 14F, 14G, 14J, and 14K closest to the sprue 182. Occurrence of sink marks was observed. No sink mark was found on the surface of the thin-walled cylindrical container obtained from the other cavities.

[0134]

Since the inventions of claims 1 to 3 of the present application are configured as described above, the molten resin is filled faster into the cavity communicating with the resin injection gate arranged at a position closer to the spool. Since each cavity is filled with molten resin and the timing is uniform, it is possible to easily manufacture a number of thin-walled molded products without quality unevenness. The mold can be modified simply by changing the cross-sectional area of the runner stopper plate runner, so it is easy to modify the mold after it has been started, and the cost of modification is low. Since the invention of claim 4 of the present application is configured as described above, the molten resin is not filled as early as in the cavity communicating with the resin injection gate disposed near the sprue, and each cavity is Since the molten resin is filled in at the same time, it is possible to easily manufacture a large number of thin-walled molded products with uniform quality.

[0135]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an entire injection molding die of the present invention.

FIG. 2 is a schematic view showing a sprue, a runner and a cavity of an example of an injection molding die according to the first aspect of the present invention.

3 is a cross-sectional view showing a thin-walled rectangular tubular container manufactured from the mold of FIG.

FIG. 4 is a schematic view showing a sprue, a runner and a cavity of another example of the injection molding die according to the first aspect of the present invention.

5 is a cross-sectional view showing a thin-walled cylindrical container manufactured from the mold of FIG.

FIG. 6 is a schematic view showing a sprue, a runner and a cavity of another example of the injection molding die according to the invention of claim 1 of the present application.

7 is a sectional view showing a thin-walled cylindrical container manufactured from the mold of FIG.

FIG. 8 is a schematic view showing a sprue, a runner and a cavity of another example of the injection molding die according to the first aspect of the present invention.

9 is a sectional view showing a thin-walled cylindrical container manufactured from the mold of FIG.

FIG. 10 is a schematic view showing a sprue, a runner and a cavity portion of an example of an injection molding die according to the invention of claim 2 of the present application.

FIG. 11 is a perspective view showing a thin plate manufactured from the mold of FIG.

FIG. 12 is a schematic view showing a portion of a sprue, a runner, and a cavity of an example of an injection molding die of the inventions of claims 3 and 4 of the present application.

FIG. 13 is a schematic view showing a sprue, a runner and a cavity of another example of the injection molding die according to the third and fourth inventions of the present application.

FIG. 14 is a schematic view showing a sprue, a runner and a cavity portion of another example of the injection molding die according to the third and fourth inventions of the present application.

FIG. 15 is a cross-sectional view showing a state in which the resin flow control member in the end of the cavity controls the resin filling in the injection molding die according to the invention of claim 4 of the present application;
FIG. 15A is a cross-sectional view showing a state in which resin filling is controlled by applying pressure to a resin filling control member inserted in the end of the cavity, and FIG. 15B shows a state in which the pressure of the resin filling control member is released. It is a sectional view showing the state where it was made to retreat from the inside of the end of the cavity.

FIG. 16 is a schematic diagram illustrating a resin flow channel flowing in a conventional mold runner, FIG. 16 (a) is a schematic diagram illustrating a resin flow channel at a first branch point, and FIG. 16 (b). Is the second
16 is a schematic view illustrating a resin flow path at a branch point of FIG.
(C) is a schematic diagram explaining the filling state of the molten resin into the resin flow path and the cavity at the third branch point.

FIG. 17 is a cross-sectional view showing a conventional molded product.

[Explanation of symbols]

 1 Mold 11 Movable Mold 12 Fixed Side Mold Plate 15 Movable Mold Mounting Plate 16 Fixed Side Mold Plate Mounting Plate 18 Runner Stripper Plate 19 Runner / Gate Connecting Plate 30 High Thermal Conductivity Mold Part 111 Core 112 Receiving Plate 113 For Overhanging Stripper plate 113b Resin flow rate adjusting member

Claims (4)

[Scope of utility model registration request] 1. An inner surface shape corresponding to a shape of a molded product to be molded is provided between a fixed side mold plate and a movable mold of a mold including a fixed side mold plate, a movable mold and a runner stripper plate. 4 or more cavities are formed, and the fixed side template is provided with cold runners branched at least at two or more branch points toward the resin injection gate of each cavity through the sprue. In the injection molding die in which the runner length to the resin injection gate communicating with the cavity is approximately equal, the end of the runner communicating with the resin injection gate located near the sprue is the end of the other runner. An injection molding die characterized in that its cross-sectional area is smaller than that of the portion. 2. A mold having a fixed-side mold plate, a movable mold, and a runner stripper plate, having an inner surface shape corresponding to the shape of a molded product to be molded between the fixed-side mold plate and the movable mold. 4 or more cavities are formed, and the fixed side template is provided with cold runners branched at least at two or more branch points toward the resin injection gate of each cavity through the sprue. In the injection molding die in which the runner length to the resin injection gate communicating with the cavity is made approximately equal, the peripheral part of the end of the runner communicating with the resin injection gate located near the sprue is An injection mold, which is made of a material having a higher thermal conductivity than the peripheral portion of the end portion of the runner. 3. A mold having a fixed-side mold plate, a movable mold, and a runner stripper plate, having an inner surface shape corresponding to the shape of a molded product to be molded between the fixed-side mold plate and the movable mold. 4 or more cavities are formed, and the fixed side template is provided with cold runners branched at least at two or more branch points toward the resin injection gate of each cavity through the sprue. In the injection molding die in which the runner length to the resin injection gate communicating with the cavity is approximately equal, the end of the runner communicating with the resin injection gate located near the sprue is the end of the other runner. The mold for injection molding is characterized in that the runner surface has a roughened surface. 4. A mold having a fixed-side mold plate, a movable mold, and a runner stripper plate, having an inner surface shape corresponding to the shape of a molded product to be molded between the fixed-side mold plate and the movable mold. 4 or more cavities are formed, and the fixed side template is provided with cold runners branched at least at two or more branch points toward the resin injection gate of each cavity through the sprue. In the injection molding die in which the runner lengths to the resin injection gate communicating with the cavity are made substantially equal, the resin flow control member is provided in the end of the cavity communicating with the resin injection gate located near the sprue. The resin flow control member is provided so that it can freely move in and out, and when the resin flow control member is connected to the pressing member and the molten resin is filled in the cavity, the resin flow control member is With a mechanism that helps to fill the molten resin into other cavities while preventing the molten resin from filling the ends in the cavity while being put into the end of the cavity and being pressed by the pressing member. A mold for injection molding, which is characterized in that