JP2010269472A - Method for molding resin part and mold for molding resin part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for molding a resin part with a high production efficiency and superior in energy saving. <P>SOLUTION: The method for molding the resin part which melts a resin 11 and molds it in a cavity space 85, includes: a temperature elevating process 21 for elevating the temperature of a cavity mold set 8 equipped with the cavity space 85; a molding process 22 for injecting a molten resin 11 into the cavity mold set 8; a cooling process 23 for cooling the cavity mold set 8; and a part taking-out process 24 for taking out a cooled resin part from the cavity mold set 8. The cavity mold set 8 is equipped with a pair of a first cavity mold 8a and a second cavity mold 8b, and the cavity mold set 8 is freely removable from a fixed mold 6 and a movable mold 7 of a mold body. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a molding method and a molding die for a resin component that does not have a weld line by molding the resin component while maintaining a temperature equal to or higher than the melting point of the resin material.

When molding a resin part, the resin is heated to a temperature equal to or higher than the melting point, and the molten resin is injected from the nozzle into the cavity space of the mold to be molded. However, when the molten resin is injected into the cavity space, the molten resin is cooled by the mold and the temperature is lowered, so that the molten resin is changed from a molten state to a semi-molten state or a solid state.
Accordingly, due to the solidification of the resin accompanying the temperature drop of the molten resin, a weld line is generated at the resin molded part where the resin merges. In particular, in the case of a ring-shaped molded product, the flow is divided in two directions from the injection port and often merges. In this case, there is a high possibility that a weld line is generated at the merge point. Depending on the product, the weld line becomes a problem with respect to strength, appearance, and seal. Therefore, efforts have been made to eliminate the weld line.

For example, in order to prevent the occurrence of weld lines, there is a method in which a material having poor thermal conductivity is used for a part constituting a cavity space for molding a resin part (Patent Document 1). According to this, the heat retention effect of the low thermal conductivity material is utilized to join the resins while maintaining the fluid resin at a relatively high temperature, thereby preventing the occurrence of weld lines.
On the other hand, as a technique related to the heating of the mold, there is a method of heating only the cavity instead of heating the entire mold by having an external heating means (Patent Document 2). According to this, it is said that heating performance can be improved and equipment cost can be reduced.

JP 2000-334743 A JP 09-104048

However, the conventional molding method for resin parts has the following problems.
In the method of Patent Document 1, the heat retention effect of the low thermal conductivity material is utilized, and the occurrence of weld lines is prevented by joining the resin while maintaining a relatively high temperature state of the injected resin flowing in the cavity. However, since a low thermal conductivity material is used for the mold, it takes much time to cool the mold, and the productivity is not good. In addition, the cooled mold must be heated again at the time of the next molding, and since the entire mold is repeatedly cooled and heated, a large amount of energy is used, which is also a problem from the viewpoint of reducing carbon dioxide. It was.
On the other hand, in the method of Patent Document 2, there is no mention of eliminating the weld line, and only when the heating is performed, not the entire mold, but only with the cavity, but when cooling, the entire mold is performed. Since it has to be cooled, it takes time to cool, and much energy is required to cool the whole, which is a problem from the viewpoint of reducing carbon dioxide.

  An object of the present invention is to solve the above-mentioned problems and to provide a molding method and a molding die for resin parts that have high production efficiency and excellent energy saving.

In order to achieve the above object, the resin component molding method and molding die according to the present invention employ the following configurations.
(1) In a method for molding a resin component in which a resin is melted and molded in a cavity space, a temperature raising step for raising the temperature of a cavity mold including the cavity space, a molding step for injecting the molten resin into the cavity die, A cooling step for cooling the cavity mold, and a component removal step for removing the cooled resin part from the cavity mold, the cavity mold including a pair of first cavity mold and second cavity mold, The cavity mold is detachable from the mold body.
(2) In the method for molding a resin component described in (1), the temperature raising step, the cooling step, and the component removing step are performed in a state where the cavity mold is removed from the mold body. To do.
(3) In the method for molding a resin part described in (1) or (2), the resin is injected while maintaining the temperature of the cavity mold at a temperature equal to or higher than the melting point of the resin.

(4) In the method for molding a resin part according to any one of (1) to (3), the cavity mold has a mechanism for clamping the first cavity mold and the second cavity mold. It is characterized by.
(5) In the method for molding a resin part according to any one of (1) to (4), the cavity mold has a mechanism capable of preventing back flow of the resin in a state of being removed from the mold body. It is characterized by.
(6) In the method for molding a resin part according to any one of (1) to (5), the resin is a material having a melting point of 300 ° C. or higher.
(7) In a mold for resin parts in which resin is melted and molded in a cavity space,
The cavity mold including the cavity space includes a pair of first cavity mold and second cavity mold, and the cavity mold is detachable from the mold body. .
(8) In the mold for resin parts described in (7),
A molding die for resin parts, comprising a mechanism for clamping the first cavity die and the second cavity die.
(9) In the molding die for resin parts as described in (7) or (8),
The first cavity mold provided with an injection hole for injecting the resin has a convex part,
The said convex part is thin, and it fits into the recessed part which a fixed mold has, and is contacting, It is a molding die of the resin component characterized by the above-mentioned.

(1) In a method for molding a resin component in which a resin is melted and molded in a cavity space, a temperature raising step for raising the temperature of a cavity mold including the cavity space, a molding step for injecting the molten resin into the cavity die, A cooling step for cooling the cavity mold, and a component removal step for removing the cooled resin part from the cavity mold, the cavity mold including a pair of first cavity mold and second cavity mold, Since the cavity mold is detachable from the mold body, the temperature raising process, the cooling process and the part removing process are separated from the mold body with the cavity mold removed from the mold body. it is possible to carry out the, can omit the time or cooling temperature of the entire mold in the prior art, it is possible to shorten the cycle time in the whole process, production efficiency Well made. In addition, the temperature of the entire mold is not raised or cooled, but only the cavity mold set consisting of a pair of first cavity mold and second cavity mold is heated or cooled, so that useless energy is not used. Energy saving can be realized.
(2) In the resin component molding method described in (1), the temperature raising step, the cooling step, and the component removing step are performed only with the cavity die in a state where it is removed from the die main body. Since it is not necessary to heat or cool, the time for heating or cooling is shortened.
(3) In the method for molding a resin part described in (1) or (2), the resin is injected while maintaining the temperature of the cavity mold at a temperature equal to or higher than the melting point of the resin. Since the molten resin injected into the space can be maintained in a molten state until joining, and does not solidify by cooling, the generation of weld lines can be prevented.

(4) In the method for molding a resin part according to any one of (1) to (3), the cavity mold is a mold clamping mechanism for clamping the first cavity mold and the second cavity mold. Therefore, the cavity mold set can be handled alone, and can be moved to each step of the temperature raising step, the cooling step, and the component taking-out step. Further, since the first cavity mold and the second cavity mold are not separated when the molten resin is injected from the mold body after injection in the molding process, the state in the molding process can be maintained.
(5) In the method for molding a resin part according to any one of (1) to (4), the cavity mold has a mechanism capable of preventing back flow of the resin in a state of being removed from the mold body. After the injection of the molten resin in the molding process, when the mold body is released from the mold clamping and removed from the mold body, the molten resin does not flow out of the cavity mold set. It can be handled and can maintain the pressure during holding at the final stage of the molding process.
(6) In the method for molding a resin part according to any one of (1) to (5), the resin is a material having a melting point of 300 ° C. or higher. Even in the case of molding, it is possible to prevent the occurrence of weld lines.

(7) In a mold for resin parts in which resin is melted and molded in a cavity space, the cavity mold including the cavity space includes a pair of first cavity mold and second cavity mold, and the cavity mold Since the mold is detachable from the mold body, a cavity mold set consisting of a pair of a first cavity mold and a second cavity mold is used instead of heating or cooling the entire mold. Only the temperature is raised or cooled, so energy can be saved without using wasted energy.
(8) In the molding die for resin parts as described in (7), since it has a mechanism for clamping the first cavity die and the second cavity die, the cavity die set alone It can be handled and moved to each step of the temperature raising step, the cooling step, and the component take-out step. Further, since the first cavity mold and the second cavity mold are not separated when the molten resin is injected from the mold body after injection in the molding process, the state in the molding process can be maintained.
(9) In the molding die for a resin part described in (7) or (8), the first cavity mold provided with an injection hole for injecting the resin has a convex portion, and the convex portion Is thin and has a feature of being in contact with the recessed portion of the fixed mold so that the heat capacity is small, and after injecting the molten resin in the molding process, the mold of the mold body When the fastening is released and the mold is removed from the mold body, the temperature of the convex portion of the first cavity mold is lowered to the temperature of the concave portion of the fixed mold. And since the molten resin is solidified and sealed in the injection hole provided in the convex portion, it can be handled without flowing out of the cavity mold set, and the pressure during holding pressure in the final stage of the molding process can be reduced. Can be held.

1 is an overall view of a molding apparatus according to a first embodiment. It is a figure which shows all the processes of the shaping | molding method of 1st Example. It is a figure which shows the structure of the cavity metal mold | die of 1st Example. It is a figure which shows the backflow prevention mechanism of 1st Example of a cavity metal mold | die. It is a figure which shows the backflow prevention mechanism of 2nd Example of a cavity metal mold | die.

Hereinafter, an embodiment embodying a method for molding a resin component according to the present invention will be described in detail with reference to the drawings.
FIG. 1 shows the configuration of the molding apparatus 1. The molding device 1 includes a screw driving device 2 for driving a screw, a hopper 3 for storing a resin material, a screw pump 10 for melting and heating the resin, a fixed die 6 and a movable die 7. On the movable mold 7, a cavity mold set 8 including a pair of first cavity mold 8a and second cavity mold 8b is disposed.
The screw pump 10 includes a plurality of heaters 4 for heating the resin, a nozzle 5 for injecting molten resin into the cavity space, a hollow cylinder 9, and a screw rotatably held in the cylinder 9. 13.

FIG. 3 shows the fastened state and the disassembled state of the cavity mold set 8.
FIG. 3A shows the fastening state of the cavity mold set 8. FIG. 3B shows an exploded state of the cavity mold set 8.
A cavity space 85 shown in (b) is formed inside the cavity mold set 8. A convex portion 89 protruding in a rectangular parallelepiped shape is formed on the contact surface of the first cavity mold 8a with the fixed mold 6. The first cavity mold 8a is formed with guide holes 82 penetrating at four places and bolt holes 83a penetrating at four places. An injection hole 84 for injecting resin is formed on the upper surface of the convex portion 89.
Four cylindrical guide pins 86 are fixed to the second cavity mold 8b at positions corresponding to the guide holes 82 formed in the first cavity mold 8a. Also, four screw holes 83b are formed at positions corresponding to the bolt holes 83a formed in the first cavity mold 8a. Further, as shown in FIG. 3B, a lower recess 85b is formed at the center of the second cavity mold 8b, and similarly, an upper recess (not shown) is formed at the center of the first cavity mold 8a. 85a is formed.

The tightening bolt 87 passes through the bolt hole 83a formed in the first cavity mold 8a and is screwed into the screw hole 83b formed in the second cavity mold 8b. The two-cavity mold 8b is screwed. At this time, the cylindrical guide pin 86 formed in the second cavity mold 8b is fitted into the guide hole 82 formed in the first cavity mold 8a, and the first cavity mold 8a and the second cavity Positioning with the mold 8b is performed.
Further, by screwing the first cavity mold 8a and the second cavity mold 8b, the cavity portion 85 is formed by the upper recess 85a of the first cavity mold 8a and the lower recess 85b of the second cavity mold 8b. It is formed.

Next, a method for molding a resin component according to the present invention will be described. FIG. 2 shows all the steps for performing the molding method of the resin part.
First, in the temperature raising step 21 as the first step, the cavity mold set 8 including the plurality of first cavity molds 8a and the second cavity mold 8b is heated and heated by a temperature raising device (not shown). The In this embodiment, the cavity mold set 8 is heated to 340 ° C. or higher.

Next, the plurality of cavity mold sets 8 whose temperature has been increased to 340 ° C. are sequentially conveyed to the molding process which is the second process. The cavity mold set 8 is disposed on the movable mold 7 of the molding apparatus 1, and the movable mold rises, and the cavity mold set 8 is sandwiched between the fixed mold 6 and the movable mold 7.
That is, in the molding step 22, the cavity mold set 8 whose temperature has been raised is attached between the fixed mold 6 and the movable mold 7 which are the mold main body, and the movable mold 7 is moved upward so that the mold is Complete. Here, the fixed mold 6 is formed with a concave portion 63 that fits into the convex portion 89 of the first cavity mold 8 a, and an injection flow path 61 is formed in the concave portion 63.
The molding apparatus 1 includes a plurality of heaters 4 above the nozzle 5, and the fixed mold 6 and the movable mold 7 are heated to 150 ° C. in advance. The resin 11 is injected into the cavity mold set 8 while being heated to 350 ° C. and melted by a plurality of heaters 4. The molding process will be described in detail below.

FIG. 4A shows a state where the resin 11 is injected in the completed mold state. By completing the mold, the injection flow path 61 formed in the fixed mold 6 is connected to the injection hole 84 of the first cavity mold 8a.
The resin 11 is supplied from the popper 3 to the screw pump 10. The screw pump 10 is rotationally driven by the screw driving device 2. The screw 13 that is rotationally driven sends out the molten resin 11 heated by the heater 4 while being pressurized toward the outlet of the nozzle 5. Thereby, the resin 11 is melted and pressurized by the screw pump 10 and injected into the fixed mold 6. In the screw pump 10, it is heated by the heater 4 and is injected from the nozzle 5 in a molten state by the rotation of the screw 13.
The fixed mold 6 has an injection channel 61 that connects the outlet of the nozzle 5 and the inlet of the cavity mold set 8, so that the molten resin 11 passes from the nozzle 5 via the injection channel 61 to the cavity mold. Injection is injected into the injection hole 84 and the cavity space 85 formed in the set 8. The shape of the cavity space 85 is the same as the shape of the resin component.

Here, a mechanism for maintaining the pressure-holding state of the resin 11 in the final molding step in the cavity mold set 8 will be described. Shown in FIG. 4 is one embodiment of a cavity mold set 8. At the time of removing the cavity mold set 8 from the fixed mold 6 and the movable mold 7, the injection hole 84 of the cavity mold set 8 needs to be closed. If the injection hole 84 is not closed, the resin 11 in the pressurized and melted state flows backward from the injection hole 84, and a nest is generated in the cavity space 85 or a dimension defect occurs.
The resin 11 is injected from the nozzle 5 into the cavity space 85 in the cavity mold set 8 via the injection flow path 61 provided in the fixed mold 6 and the injection hole 84 formed in the first cavity mold 8a. The A cooling medium flow path 62 is formed in the fixed mold 6. The cooling medium flow path 62 includes a plurality of annular flow paths around the injection flow path 61 and the convex portion 89 with the injection flow path 61 as a central axis. A cooling medium 64 for cooling the gate part 12 of the resin component flows through the cooling medium flow path 62. The injection hole 84 has a taper with a smaller cross-sectional area as it is closer to the fixed mold 6.
The convex portion 89 of the first cavity mold 8 a provided with the injection hole 84 is fitted and brought into contact with the concave portion 63 of the fixed mold 6. While securing the injection flow path 61, the convex portion 89 is narrowed to reduce the heat capacity.

As shown in FIG. 4B, the resin 11 is injected by the cooling medium 64 when the mold 11 is separated from the fixed mold 6 by the lowering of the movable mold 7 after the injection is completed. By adjusting the temperature of the flow path 61 and the injection hole 84 part of the first cavity mold 8a, the gate part 12 is cooled first and becomes a solid state, so that the molten resin 11 in the space of the cavity mold set 8 is obtained. Is sealed by the solid-state gate portion 12, can prevent backflow of the molten resin 11 in the cavity space 85, and can maintain the pressure-holding state of the resin 11. As shown in FIG. 4B, since the injection hole 84 has a draft taper with a smaller cross-sectional area as it is closer to the fixed mold 6, the gate portion 12 closing the injection hole 84 is in a molten state. Even if the pressure of the resin 11 is received, it does not pop out. On the other hand, when the cavity mold set 8 is disassembled, the gate portion 12 can be pulled out by the drawing taper.
And it is conveyed to the cooling device which is not shown in figure, and the cavity metal mold | set set 8 cools by the cooling process 23 which is a 3rd process.
After the cavity mold set 8 is cooled, the fastening bolts 87 are removed and disassembled in the component removal process which is the fourth process 24, and the resin component molded in the cavity space 85 is removed. Thereafter, the cavity mold set 8 is again returned to the first step and reheated.

  As described above in detail, according to the resin component molding method of this embodiment, in the resin component molding method in which the resin 11 is melted and molded in the cavity space 85, the cavity mold set 8 including the cavity space 85 is used. The temperature is increased from the temperature raising step 21 for raising the temperature, the molding step 22 for injecting the molten resin 11 into the cavity die set 8, the cooling step 23 for cooling the cavity die set 8, and the cavity die set 8. The cavity mold set 8 includes a pair of first cavity mold 8a and second cavity mold 8b, and the cavity mold set 8 is a mold body. Since the mold 6 and the movable mold 7 are detachable, the temperature raising step 21, the cooling step 23, and the component removing step 24 are performed in the cavity mold set 8 Since it can be performed separately from the mold body in a state of being removed from the mold body, the time for heating or cooling the entire mold in the prior art can be omitted, and the cycle time in all processes can be shortened. Production efficiency. Also, rather than heating or cooling the entire mold, only the cavity mold set consisting of a pair of first cavity mold and second cavity mold is heated or cooled, so no wasted energy is used. Energy saving can be realized.

Further, since the temperature raising step 21, the cooling step 23, and the component removing step 24 are performed only with the cavity mold set 8 in a state of being removed from the mold body, it is not necessary to heat or cool the entire mold. The time for heating or cooling is shortened.
Further, since the resin 11 is injected while maintaining the temperature of the cavity mold set 8 at a temperature equal to or higher than the melting point of the resin 11, the molten resin 11 injected into the cavity space 85 is kept until the merge. Since the molten state can be maintained and there is no solidification due to cooling, the generation of weld lines can be prevented.

The cavity mold set 8 has a mechanism for clamping the first cavity mold 8a and the second cavity mold 8b in a state where the cavity mold set 8 is detached from the mold body. 8 can be handled independently and can be moved between the steps.
Further, since the cavity mold set 8 has a mechanism capable of preventing the back flow of the resin when it is detached from the mold body, the cavity mold set 8 can prevent the back flow of the resin alone. Therefore, when removing from the mold body, the resin does not flow out of the cavity mold set 8, and the pressure during holding can be maintained even when the resin is in a molten state.
Further, since the resin 11 is a material having a melting point of 300 ° C. or higher, it is possible to prevent the occurrence of weld lines even when a resin part is molded with a resin having a high melting point.

Next, a second embodiment will be described. The second embodiment is different from the first embodiment only in the mechanism for holding pressure alone in the cavity mold set 8, so only the differences will be described in detail and the other descriptions will be omitted.
In FIG. 5A, the resin 11 is injected from the nozzle 5 into the injection hole 84 and the cavity space 85 of the cavity mold set 8 through the injection flow path 61 provided in the fixed mold 6. The fixed die 6 is temperature-controlled at 180 ° C. to 200 ° C. during molding, but the temperature is lower than the temperature 340 ° C. of the molten resin 11, and the convex portion 89 provided with the injection hole 84 is thin and has a small heat capacity. When the fixed mold 6 and the cavity mold set 8 are separated after the injection of the resin 11 is completed, the temperature of the fixed mold 6 is low as shown in FIG. The gate part 12 of the resin part formed in the path 61 formed in the above is cooled first and solidified, and the molten resin 11 in the space of the cavity mold set 8 is sealed in the gate part 12 in the solid state. In addition, pressure can be maintained in itself and the backflow of the molten resin can be prevented.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, and various applications are possible.
For example, in the present embodiment, the first cavity mold 8a and the second cavity mold 8b are fastened by screw fastening with a fastening bolt 87. However, if a sufficient fastening force can be secured, one-touch fastening is possible. Tools may be used.

DESCRIPTION OF SYMBOLS 1 Molding device 2 Screw drive device 3 Hopper 4 Heater 5 Nozzle 6 Fixed mold 7 Movable mold 8 Cavity mold set 8a First cavity mold 8b Second cavity mold 10 Screw pump 11 Resin 13 Screw 21 Temperature rising process 22 Molding process 23 Cooling process 24 Parts removal process

Claims (9)

In the molding method of resin parts that melt resin and mold in the cavity space,
A temperature raising step for raising the temperature of the cavity mold comprising the cavity space;
A molding step of injecting molten resin into the cavity mold, a cooling step of cooling the cavity mold,
From the cavity mold, it has a part removal step of taking out the cooled resin part,
The method of molding a resin component, wherein the cavity mold includes a pair of first cavity mold and second cavity mold, and the cavity mold is detachable from a mold body. In the molding method of the resin component according to claim 1,
The method of molding a resin part, wherein the temperature raising step, the cooling step, and the component removing step are performed in a state where the cavity mold is removed from the mold body. In the molding method of the resin component according to claim 1 or 2,
A method for molding a resin component, wherein the resin is injected while maintaining a temperature of the cavity mold at a temperature equal to or higher than a melting point of the resin. In the molding method of the resin component according to any one of claims 1 to 3,
A method for molding a resin component, comprising a mechanism for clamping the first cavity mold and the second cavity mold. In the molding method of the resin component according to any one of claims 1 to 4,
The method for molding a resin part, wherein the cavity mold has a mechanism capable of preventing a back flow of the resin in a state where the cavity mold is detached from the mold body. In the molding method of the resin component according to any one of claims 1 to 5,
The method for molding a resin part, wherein the resin is a material having a melting point of 300 ° C. or higher. In a mold for resin parts that melts the resin and molds it in the cavity space,
The cavity mold including the cavity space includes a pair of first cavity mold and second cavity mold, and the cavity mold is detachable from the mold body. . In the molding die for resin parts according to claim 7,
A molding die for resin parts, comprising a mechanism for clamping the first cavity die and the second cavity die. In the molding die of the resin part according to claim 7 or claim 8,
The first cavity mold provided with an injection hole for injecting the resin has a convex part,
The said convex part is thin, and it fits into the recessed part which a fixed mold has, and is contacting, It is a molding die of the resin component characterized by the above-mentioned.

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