JPS62146607A - Molding process for functional parts with engineering plastic thick wall - Google Patents

Abstract

PURPOSE:To enable the functional parts with engineering plastic thick wall and without the occurrence of sinks or voids to be molded by heating molds while arranging a good heat-conductive member in a cavity. CONSTITUTION:A good heat-conductive member 3 is received in the positioning hole 9 on the bottom force 6 of molds 7. A rod heater 11 is inserted in a driving shaft mounting hole 10 of the good heat-conductive member 3. The engineering thermosetting plastic material is injected into a cavity 7, and the top force 5 and the bottom force 6 of the molds are heated to a specified temperature. At this time, the good heat-conductive member 3 is caused to be in contact with the bottom force 6, and as it is made of metal, when it is heated a little by a heater 11, its temperature becomes same as the temperature of the molds. After heating, when a specified time passes, the engineering plastic material in the cavity 8 is heated by the heat of the top and bottom forces of the molds and the good head-conductive member 3, and is cured. After perfect curing, the heater 11 is drawn out. Accordingly, the functional parts are uniformly cured in short time, and inner sinks voids do not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of molding functional parts such as gears, cams, and pulleys from engineering plastics.

(Prior Art) Generally, the above-mentioned functional parts are molded using engineering plastic materials by injection molding, monomer casting, or the like.

(Problems to be Solved by the Invention) However, with these methods of molding engineering plastic functional parts, it is possible to produce large functional parts for automobiles, such as timing gears and pulleys with a wall thickness of 10+n or more. If mass production is attempted, sink marks and voids will occur in the resulting functional parts, making it impossible to obtain stable functional parts. Conventionally, engineering plastic functional parts with a wall thickness of 10B or more have not been mass-produced.

In other words, when trying to mold an engineering plastic functional part with a wall thickness of 10 mm or more, because the functional part is thick, the part of the engineering plastic material injected into the cavity close to the mold surface and the mold surface The curing speed is different from the part far from the mold, resulting in an unbalanced molding shrinkage. For this reason, shrinkage voids are likely to occur in the center of the product in the thickness direction, and sink marks are also likely to occur on the surface of the product due to shrinkage in areas that are slow to cure or cool.

Therefore, the present invention aims to solve the above-mentioned problems of the prior art, and when molding thick-walled engineering plastic functional parts with a wall thickness of 10 m or more, the resulting functional parts are free from sink marks. The purpose of the present invention is to provide a method for molding thick-walled engineering plastic functional parts that does not generate voids or voids.

(Means for Solving the Problems) The method for molding thick-walled engineering plastic functional parts of the present invention provides a method for molding thick-walled engineering plastic functional parts by placing a good amount of heat in the cavity of a mold for the functional parts. A thermal member is arranged so that heat is transferred from the mold and maintained at approximately the same temperature as the surface of the mold, and while the mold is heated, an engineering plastic material is injected into the cavity of the mold. In particular, the good heat conductive member used in the method for molding thick-walled engineering plastic functional parts of the present invention, which is characterized by being cured or cooled thereafter, becomes a part of the engineering plastic functional parts to be molded. A good heat conductive member may be placed in the cavity only for the purpose of heating and hardening the engineering plastic material, but it may also be used as a reinforcing member for the functional part concerned, or especially when the functional part is a gear, a pulley, etc. It is preferable that the member forming the shaft hole is a part of the functional component. This good heat conductive member is
It may be composed only of metal pipes, etc., but for example, when a metal plate is further connected to the metal pipe and placed in the cavity, the position is equidistant from the upper mold surface and the lower mold surface of the cavity. It is more advantageous to uniformly heat and harden the engineering plastic material by arranging the metal plate to be located at the center.

Of course, it is also possible to have a shape in which a number of metal plates are connected to a metal pipe.

In addition, the good heat conductive member may be placed in the cavity of the molding die in such a way that heat is transferred from the same mold and maintained at approximately the same temperature as the mold surface, and the good heat conductive member is directly molded. The structure may be such that it comes into contact with the mold, or the structure may include a heater for heating the heating member. Of course, if the good heat conductive member is brought into contact with the mold and the heater is inserted, the good heat conductive member will be heated by the heat transfer from the mold and by the heater if necessary, so that it will not touch the mold. It becomes very easy to heat the members with good heat conductivity to approximately the same temperature.

The engineering plastic material used in the present invention is
It may be a thermosetting resin or a thermoplastic resin, for example, polyamide, polyacetal, PDT, PET, modified PPO.
Resins such as , phenol, epoxy, polycarbonate, and special engineering plastics can be used.

In the method of the present invention, if the engineering plastic material is a thermosetting resin, a curing treatment is performed, and if it is a thermoplastic resin, a cooling treatment is performed to harden the engineering plastic material in the mold. to make thick-walled molded products.

(Function) In the method for molding thick-walled engineering plastic functional parts of the present invention, by arranging the member with good heat conductivity, it is possible to heat and cool the member and the mold surface of the molding die so as to maintain them at approximately the same temperature. Therefore, the engineering plastic material injected into the mold cavity is heated to the same degree as the mold surface and the heat conductive material, and as a result, the entire material is kept at approximately the same temperature during subsequent curing or forced cooling. The temperature decreases while being maintained at Furthermore, in the past, the distance between heating parts for engineering plastic materials was the same as the distance between opposing mold surfaces, but in the method of the present invention, a metal plate is connected to an iron pipe with a good heat conductive member as described above. When a good heat conductive member is placed between opposing mold surfaces, the distance between the heating parts becomes much shorter than in the past, making it easier for heat to spread throughout the engineering plastic material. Therefore, the engineering plastic material of the mold can be uniformly cured or cooled.

(Example) Hereinafter, an example of the method for molding a thick-walled engineering plastic functional part of the present invention and the obtained thick-walled functional part will be described based on the drawings.

In this embodiment, as shown in FIG. 1, a good heat conductive member 3 consisting of a metal collar member 1 for mounting a drive shaft and a metal plate 2 welded and fixed to this collar member 1 is attached to the shaft hole. An automotive timing gear with a wall thickness of 10 m was molded from an engineering plastic material by a monomer casting method.

Note that fins 4 are attached to the metal plate 2 of the good heat conductive member 3 to enhance the thermal conductivity to the engineering plastic material and to strengthen the bond with the engineering plastic material.

Next, a method for molding the engineering plastic functional part of this embodiment will be explained with reference to FIG. 1.

First, the good heat conductive member 3 is placed in the positioning hole 9 provided in the lower mold 6 of the mold 7. And this good heat conductive member 3
Insert the rod heater 11 into the drive shaft mounting hole 10 of the.

Next, a thermosetting engineering plastic material is injected into the cavity 8, and the upper mold 5. The lower mold 6 is heated to a predetermined temperature. At this time, since the good heat conductive member 3 is in contact with the lower mold 6 and is made of metal, the heat of the lower mold 6 is transmitted and the temperature rises, but by slightly heating it with the heater 11, Bring to the same temperature as the mold. After a certain period of time has elapsed after heating, the engineering plastic material in the cavity 8 is transferred to the upper mold 5. Lower mold 6
Then, it is warmed and hardened by the heat of the good heat conductive member 3.

After curing is completed, the heater 11 is removed and the obtained timing gear is placed in the upper mold 5. Take it out from the lower mold 6. At this time, the heat capacity of the heater 11 is smaller than the heat capacity of the mold collar member 1 for attaching the drive shaft of the good heat conductive member 3, and since it contracts first, the heater 11 can be easily removed.

In this embodiment, when the good heat conductive member is fitted into the positioning hole 9 in the cavity 8 and arranged, the metal plate 2 is equidistant from the mold upper surface 12 and the mold lower surface 13 of the cavity 8. The structure is such that it is located at a position where Therefore, the wall thickness of the molded automotive timing gear is 10
Although it is a seal, the engineering plastic material has a mold upper surface 12 and a metal plate 2 located at an interval of approximately 5 cranes.
d between the mold lower surface 13 and the other plate surface 15 of the metal plate 2 d2. The upper mold 5 of the mold will be heated respectively. Since the lower mold 6 and the good heat conductive member 3 were heated to the same temperature, the functional component was uniformly cured in a short time, and no internal shrinkage voids were generated. Note that the upper mold 5 and lower mold 6 used in this example are each provided with temperature adjustment holes 16 to facilitate obtaining desired curing conditions.

(Reference Example) As a means to prevent the occurrence of sink marks and voids when molding thick-walled engineering plastic functional parts, for example, a functional component reinforcing member 17 as shown in FIG. Similar to the method of molding meat functional parts, a method of placing it inside the cavity of a mold can be considered.

In this method, the functional component reinforcing member 17 is constructed by welding an iron rod 18 to a metal collar member l for attaching a drive shaft, and attaching a mesh-like cloth 19 that does not react with the molding material such as glass cloth to the iron rod 18 with a diameter of 4 mm. It is constructed by wrapping it around to form a crane.

This functional component reinforcing member 17 is placed in the cavity 8 formed by the upper mold 5 and the lower mold 6 to mold a functional component with a wall thickness of 10+n, in substantially the same manner as in the embodiment. In this molding method, since the diameter of the cross 19 is 4 mm, the wall thickness (d3+d,) of the engineering plastic material of the functional part molded between the upper mold surface 12 and the lower mold surface 13 is is 611. therefore,
Enables uniform heating and uniform curing of engineering plastic materials. Furthermore, the mesh-like cloth 19 is impregnated with the engineering plastic material to form a strong bond, resulting in a so-called anchor effect.

(Effects of the Invention) In the method for molding thick-walled engineering plastic functional parts of the present invention, by arranging a member with good heat conductivity in the cavity, the member and the mold surface of the molding die are kept at approximately the same temperature. Therefore, when molding thick-walled engineering plastic functional parts, the difference between the parts of the engineering plastic material injected into the cavity that are close to the mold or parts that have good heat conductivity is There is no difference in curing speed, and there is no variation in molding shrinkage after curing. Therefore, it is possible to mold thick-walled engineering plastic functional parts without sink marks or voids.

Therefore, the molding method of the present invention has made it possible to mass-produce engineering plastic functional parts with a wall thickness of 10 m or more with stable quality.

Further, the good heat conductive member used in the method for molding thick-walled engineering plastic functional parts of the present invention is integrated into the obtained functional part as a functional part reinforcing member or the like. For this reason, the use of materials with good heat conductivity not only does not cause disadvantages such as reduced workability or increased production costs compared to conventional molding methods, but also has the secondary effect of improving the strength of functional parts. It also plays.

[Brief explanation of the drawings] Figure 1 is a cross-sectional view of a mold to show the method for molding the engineering plastic thick-walled functional parts of the example. Figure 2 is the engineering plastic thick-walled functional parts and products of the reference example. FIG. 3 is a cross-sectional view of a mold for showing a molding method. In the figure, 1... Metal collar member for drive shaft attachment 2... Metal plate 3... Good heat conductive member 4... Fin
5... Upper mold 6... Lower mold 7... Mold 8... Cavity 9... Positioning hole 10... Drive shaft mounting hole 11... Rod heater fang 1 Fig. 1... 16yy7) Hanging metal collar livestock p material 2 with shoulder rest
...Metal plate 3...Good heat conductive member 4...Fin 5...Upper mold 6--Lower mold 7
... Mold 8... Capacity, 9... Standing -
Jja'5R10...1% double 13'/ya7torei1
Lll... rod heater

Claims (1)

[Claims] When molding a thick-walled functional part of engineering plastic, a member with good heat conductivity is placed in the cavity of a mold for the functional part so that heat is transferred from the mold and the mold surface is approximately the same as that of the mold surface. An engineering plastic thick-walled functional part characterized in that the engineering plastic material is injected into the cavity of the mold while heating the mold and injecting the engineering plastic material into the cavity of the mold, followed by curing or cooling. Molding method.