JP2005040983A - Mold for molding resin pipe molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To release a core mold from a product resin pipe sufficiently smoothly without causing the fear of the adhesion of a mold release agent to the outer surface of the product resin pipe and the damage of the product resin pipe. <P>SOLUTION: In this mold equipped with an outer mold 1 and the core mold 2 and used for molding the resin pipe in a demarcated cavity 9, a tapered draft is provided on the cavity demarcating part 5 of the core mold 2 over the total length thereof and the surface roughness of the cavity demarcating part 5 is set to 0.5-1.0 μm as arithmetic average roughness (Ra). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００２５】
【発明の効果】
以上に述べたとこらから、明らかなように、この発明によれば、とくに、コア型のキャビティ区画部分の表面粗さを０．５〜１．０μｍとすることにより、そのキャビティ区画部分に特別大きな抜き勾配を付与する必要なしに、ひいては、それらを原因とする問題のことごとくを十分に取り除いて、成形型内の樹脂パイプに対し、キャビティ区画部分を、そのパイプの損傷等の発生なしに極めて円滑に離型させることができる。
【図面の簡単な説明】
【図１】この発明の実施形態を示す断面図である。
【図２】従来技術を示す断面図である。
【図３】従来技術を型開き状態で示す断面図である。
【図４】樹脂成形品を例示する斜視図である。
【符号の説明明】
１ 外型
２ コア型
３ ゲート型
４ 中空部
５ キャビティ区画部分
６ ランナ
７ ゲート
８ キャビティ窪み
９ キャビティ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molding die for a resin pipe molded product suitable for use as a photosensitive drum applied to, for example, a copying apparatus, an image recording apparatus, a printer, and the like. The present invention proposes a technique for advantageously reducing the core-type drawing resistance.
[0002]
[Prior art]
FIG. 2 shows an example of a molding die used for molding a resin pipe having an outer mold and a core mold, preferably seamless, in other words, without transfer of a mold parting line. There is something.
[0003]
This molding die includes a hollow outer mold 21 having a tubular shape as a whole, and a core mold 23 having a cavity partition portion 22 disposed on one end side of the outer mold 21 and entering the hollow portion of the outer mold 21. The gate mold 25 is disposed on the other end side of the outer mold 21 and partitions the gate 24. Here, the core mold 23 may be an end mold that closes one end of the outer mold hollow portion. The gate mold 25 also functions as an end mold for molding the top wall portion of the molded product.
[0004]
According to such a molding die, the resin material is injected through the gate 24 into the molding cavity 26 defined by the cooperation of the respective molds 21, 23, 25 in the mold closing posture. Here, a resin pipe having a top wall and a flange integral therewith is molded.
[0005]
Then, the resin pipe is taken out from the molding die by cooling the resin pipe and separating the core mold 23 and the gate mold 25 from each other in the required order with respect to the outer mold 21 as shown in FIG. After that, the resin pipe P remaining in the outer mold 21 can be released from the outer mold 21 using, for example, an ejector pin or the like (not shown), and removed from the resin mold P by appropriate means.
FIG. 4 is a perspective view showing the appearance of the resin pipe taken out in this way.
[0006]
[Problems to be solved by the invention]
However, in molding the resin pipe P using such a molding die, when the molded resin pipe P is closely contacted with the cavity partition portion 22 of the core mold 23, many of them are mirror-finished. The release resistance of the cavity partitioning portion 22 from the inner peripheral surface of the pipe is increased. Therefore, when a large pulling force for releasing the mold is applied to the core mold 23, the resin pipe P, as shown in the figure. However, there is a problem that the flange portion F of the pipe P is easily deformed, the base portion of the flange portion F is easily damaged, and the length of the pipe-shaped portion of the resin pipe P exceeds 200 mm. Was particularly serious.
[0007]
Therefore, in order to reduce the mold release resistance of the core mold 23, a release agent is applied to the surface of the cavity partition portion 22, the draft angle of the cavity partition portion 22 is increased, and the core portion 22 is subjected to a surface treatment. However, according to the first method of applying the release agent, there is a high possibility that the release agent adheres to the outer surface of the resin pipe P. In the subsequent formation of the coating film on the surface, there was a problem of causing poor adhesion of the coating film, and in the molding of the resin pipe P, a release agent may be frequently applied. In the second method of increasing the draft angle of the cavity section 22, the change in the thickness of the pipe P in the length direction increases, and the pipe P has a required dimension. In some cases, physical properties cannot be given. Rutotomoni, product pipe P due to variations in the cooling rate of the pipe P or the like in a molding die, there is a problem that a relatively large deformation is undeniable.
Further, the surface treatment method in which the cavity partition portion 22 is coated with hard chrome coating, molybdenum coating, or the like has a problem that the effect is small as compared with the above case.
[0008]
The present invention has been made to solve such problems of the prior art, and the object of the present invention is to provide a resin pipe molded and cooled in a molding cavity. Despite the excellent mold releasability, all the inconveniences caused by the prior art, such as the unexpected attachment of the mold release agent to the outer surface of the pipe and the large thickness change in the axial direction of the pipe, were sufficiently solved. In providing a molding die for resin pipe moldings.
[0009]
[Means for Solving the Problems]
A molding die for a resin pipe molded product according to the present invention includes an outer mold and a core mold, and is for molding a resin pipe in a cavity to be partitioned. Is provided over the entire length, and the surface roughness of the cavity section is in the range of 0.5 to 1.0 μm in terms of arithmetic average roughness (Ra) defined by JIS B0601.
[0010]
When the cavity section of the core mold is mirror-finished and its arithmetic average roughness (Ra) is a small one having a roughness of about 0.1 to 0.2 μm, it is within the cavity of the molding mold. The resin pipe that has been molded and cooled there has a very high degree of adhesion to the cavity section, and it is difficult for air to enter between them. The mold release resistance to inevitably increases.
[0011]
However, since the surface roughness of the cavity section is 0.5 to 1.0 μm in terms of arithmetic average roughness (Ra), the surface roughness is 5 to 10 times that of the mirror finish. Even if the pipe is in close contact with the cavity partition due to cooling in the cavity, the air between the cavity partition and the resin pipe is slightly affected, such as by the action of an extraction external force on the core mold. As a result of rapid penetration, this substantially eliminates the mold release resistance of the cavity section, so that the mold opening of the core mold is performed sufficiently smoothly by the action of a small external force. Become.
Therefore, even if the molded resin pipe has a flange portion as described in the prior art, the risk of deformation, breakage, etc. thereof can be sufficiently removed.
[0012]
Here, when the surface roughness of the cavity partition portion is less than 0.5 μm, the roughness is too small, leading to an artificial entry of air between the cavity partition portion and the resin pipe. On the other hand, if it exceeds 1.0 μm, it is inevitable to increase the mold release resistance due to the excessive roughness even though the draft is provided in the cavity section.
[0013]
As described above, since the release resistance of the cavity partition portion can be sufficiently reduced without applying the release agent to the core partition portion, surface treatment, etc. The possibility of adhesion to the outer surface of the resin pipe can be completely removed.
[0014]
In such a molding die, preferably, the inclination angle of the draft angle of the cavity partitioning portion is set in the range of 3 to 9 minutes, while effectively reducing the mold release resistance of the core die, the resin pipe in the axial direction The thickness change is advantageously suppressed. In other words, if the tilt angle is less than 3 minutes, it is difficult to reduce the mold release resistance to a sufficient level even if the surface roughness as described above is imparted to the cavity partition part, while if it exceeds 9 minutes. In a relatively long resin pipe, there is a possibility that the influence of the wall thickness change becomes obvious.
[0015]
These are particularly effective when the length of the cavity section is 200 mm or more.
If the length is less than 200 mm, the release resistance of the core type is not so high, so it is difficult to confirm the conspicuity of the effect by setting the surface roughness of the cavity partition portion in the above range.
[0016]
Furthermore, it is preferable that the average diameter of the cavity partition portion is 15 mm or more, especially 16 to 30 mm.
This is because the release resistance is not so high in the case where the diameter is less than 15 mm, as in the case of the length.
In addition, it is desirable that the diameter of the core mold base is 3 mm or more smaller than the inner diameter of the outer mold. Thereby, since the thickness of the thinnest part becomes 1.5 mm or more, it is possible to ensure sufficient filling of the resin and give the pipe the required strength.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below based on the drawings.
FIG. 1 is a cross-sectional view showing a molding die according to the present invention in a closed state and an enlarged sectional view of a core die, and this molding die has the same basic structure as described in the prior art.
[0018]
That is, 1 in the figure shows a hollow outer mold having a tubular shape as a whole, 2 is a core mold disposed on one end side of the outer mold 1 and closing one end of the hollow portion, and 3 is 1 shows a gate mold disposed on the other end side of the outer mold 1.
[0019]
Here, the core mold 2 is provided with a cavity partition portion 5 that enters the hollow portion 4 of the outer mold 1 having a circular cross-sectional shape and shares a central axis with the hollow portion 4. The gate mold 3 includes a gate 7 that communicates with the runner 6, and opens into the gate 7, and in cooperation with the outer mold 1, the cavity recess 8 that contributes to the formation of the inclined wall flange of the molded product. With
[0020]
The molding die thus configured defines a cavity 9 corresponding to the shape of the molded product in the mold closed state of each of the molds 1, 2, and 3 as shown in FIG.
By the way, the cavity partition portion 5 of the core mold 2 here is tapered as shown in the enlarged cross-sectional view of FIG. 1B, and preferably has a tapered draft angle, preferably 3 to 9 minutes. Is provided over the entire length, and the surface roughness of the cavity partition portion 5, particularly the peripheral surface portion thereof, is defined by JIS B0601 by, for example, an appropriate type of blasting or filing. The average roughness (Ra) is in the range of 0.5 to 1.0 μm.
[0021]
After the resin pipe molded in the cavity 9 by injection molding or the like is cooled and hardened in the cavity 9 by using the molding die as described above, the molds 1, 2, and 3 are opened by the mutual mold opening operation. When taking out from the molding die, here, the cavity partition portion 5 of the core mold 2 is given the draft as described above, and the surface roughness is given. Due to the input to the mold 2 due to the action of the mold opening external force, it can be relatively displaced relatively in the direction of withdrawal from the resin pipe. Once such relative displacement occurs, Since the close contact state is completely released, the cavity partition portion 5 is smoothly retracted and displaced from the pipe without exerting a large force on the flange portion or the like of the resin pipe. Can.
[0022]
Therefore, according to this molding die, the resin pipe can be effectively protected from deformation, damage and the like without requiring application of a release agent to the cavity partition portion 5 or the like.
This is particularly effective when the length of the cavity partition part 5 is 200 mm or more and when the average diameter of the part is 15 mm or more, especially 16 to 30 mm.
[0023]
【Example】
In forming a resin pipe having a form as shown in FIG. 4 made of a polyamide-based resin, having an outer diameter of 30 mm, an average inner diameter of 26.5 mm, a total length of 280 mm, and a pipe portion of 260 mm in length. When the product quality was examined using the surface roughness of the cavity section of the core mold as a parameter, the results shown in Table 1 were obtained.
[0024]
[Table 1]

[0025]
【The invention's effect】
As is apparent from the above description, according to the present invention, the surface roughness of the core-type cavity partition portion is set to 0.5 to 1.0 [mu] m. Without the need to provide draft, by removing all the problems caused by them, the cavity section of the resin pipe in the mold is very smooth without causing damage to the pipe. Can be released.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a conventional technique.
FIG. 3 is a cross-sectional view showing the prior art in a mold open state.
FIG. 4 is a perspective view illustrating a resin molded product.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer type | mold 2 Core type | mold 3 Gate type | mold 4 Hollow part 5 Cavity division part 6 Runner 7 Gate 8 Cavity hollow 9 Cavity

Claims (4)

A molding die comprising an outer mold and a core mold, and molding a resin pipe in a partitioned cavity,
Resin that provides a draft angle that tapers in the cavity section of the core mold over its entire length, and that the surface roughness of the cavity section is in the range of 0.5 to 1.0 μm in terms of arithmetic average roughness (Ra) Mold for pipe molding products. The molding die for a resin pipe molded product according to claim 1, wherein the draft angle is in a range of 3 to 9 minutes. The molding die for a resin pipe molded product according to claim 1 or 2, wherein the length of the cavity partition portion is 200 mm or more. The mold for molding a resin pipe according to any one of claims 1 to 3, wherein an average diameter of the cavity partition portion is 15 mm or more.

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