JPS62152832A - Molding of plastic by means of high frequency heating - Google Patents

Abstract

PURPOSE:To attempt improvement in the working efficiency of a high frequency heating apparatus by setting a mold in the high frequency heating apparatus while the old is being closed and held by clamping parts. CONSTITUTION:A molding material 10 is placed on the surface of a bottom force 1 formed of a silicone resin. The bottom force 1 is then placed on a conductive plate 3 formed of aluminium. A conductive plate 2 formed of aluminium is placed on the mold surface side of the bottom force 1. The mold is then pressed by means of a press 4 from the upper side of the conductive plate 2 and the conductive plate 2, the bottom force 1 and the conductive plate 3 are clamped by using an aluminium clamp 5 while the pressing is being kept. After the pressing is released, the conductive plate 2, the bottom force 1 and the conductive plate 3 are being kept in a body. The conductive plates 2, 3 and the bottom force 1 being clamped and fixed by the clamp 5 is placed between electrodes 7, 8 of a high frequency heating apparatus and a high frequency voltage is applied while the electrodes is being contacted with them under a specified pressure. A molding is thereby formed along the inner surface of the cavity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermoforming method using high frequency. The method of the present invention is used when foam molding thermoplastics.

[Prior Art] Conventionally, foam molding of plastics has been carried out using dielectric heating using high-frequency voltage. For example, the fourth example uses high-frequency heating for foam molding of thermoplastic resin.
The method shown in FIG. 5 and FIG. 5 is known.

To explain this method, first, a molding material 200 to which a foaming agent has been added is placed in a lower mold 100 of a split mold, and the mold is clamped with an upper mold 300. This mold is placed in a high-frequency heating device, sandwiched between electrodes 400 and 500, and a high-frequency voltage is applied to heat and foam mold the molding material 200. Then, molding is performed while pressing the electrode 400 and the electrode 500 with a press 600 or the like to prevent the split mold from opening due to the pressure of foaming.
Even after foaming is completed, the pressurized state is maintained and the product is cooled in a high-frequency heating device. After cooling, the split mold is removed from the high-frequency heating device, the mold is opened, and the molded product is taken out, thereby completing the molding.

[Problems to be Solved by the Invention] In the conventional method described above, cooling is performed while maintaining pressure within the high-frequency heating device, and the cooling time generally takes a long time. There was a problem that the mobility rate was low.

The present invention has been made in view of these problems,
The present invention provides a method for molding plastics using high-frequency heating, which greatly improves the movability of a high-frequency heating device and enables efficient molding.

Means for Solving Problem L] The method for molding plastics by high-frequency heating of the present invention includes a step of placing a molding material in a cavity of a mold in which at least one of the split molds is formed of an insulating material; A mold clamping process in which the mold is clamped and held by a clamping member, and the clamped and held mold is placed in a high-frequency heating chamber and a high-frequency voltage is applied to heat the molding material and the cavity mold is heated. A molding process of forming a molded body along the surface, a solidification process of taking out the clamped mold from the high-frequency heating device and cooling and solidifying the molded body, and a solidification process of opening the mold to form the molded body. It is characterized by consisting of a demolding process for taking out the mold.

The mold used in the present invention is made of a conventional insulating material with a small dielectric constant, such as silicone resin or Teflon resin. The entire mold may be made of an insulating material, or either the upper mold or the lower mold may be made of an insulating material. In the placement step, the molding material is placed in the cavity of this mold. Here, as the molding material, a mixture of a thermoplastic resin and a foaming agent, or a resin mixture before crosslinking and curing can be used.

The mold with the molding material placed thereon is clamped.

In this mold clamping step, which is a feature of the present invention, the mold is clamped and held in a state where it is clamped by clamping members.

If the mold can withstand the clamping force of the clamping members, the mold can be directly clamped and clamped, but in the case of high-frequency heating, the mold is generally made of resin and cannot withstand the clamping force. Since this is often the case, it is desirable to sandwich the material with conductive plates or the like interposed therebetween.

The conductive plate used here applies a high frequency voltage to the mold by contacting the electrode of the high frequency heating device, and the larger the contact area with the mold, the more uniformly the molding material is heated. Note that the conductive plate needs to be a good electrical conductor, and is preferably made of aluminum or aluminum alloy, which is not a ferromagnetic material. If the entire mold is made of an insulating material, the mold is sandwiched between two conductive plates in the mold clamping step.

Also, either one of the split types can be constructed of a conductive plate.

Mold clamping is performed by applying a predetermined pressure to the mold using a press or the like, as in the past. In the present invention, the clamping member clamps the mold while maintaining this pressurized state. Here, the clamping member may be any member as long as it can hold the mold clamping, and various materials such as bolts and nuts, clamps, etc. can be used. In particular, it is easy to clamp and release the clamp.
Preferably, a clamp is used. Note that when using a conductive plate, the clamp will come into contact with the conductive plate, so to prevent short circuits caused by the clamp, the clamp itself should be covered with an insulator, or the clamp itself should be covered with an insulating material. It is necessary to do something like clamp it.

In the molding process, the clamped molded body is placed in a high-frequency heating device, and a high-frequency voltage is applied to the mold. Generally, a high frequency voltage is applied by bringing an electrode of a high frequency heating device into surface contact with a mold or a conductive plate.

Then, the molding material in the mold is heated by dielectric loss, and molding is performed by foaming, vulcanization, hardening, etc.

After the molding is completed, a solidification process is performed. In the present invention, the mold is not clamped by the electrodes of the high-frequency heating device, but is clamped independently of the high-frequency heating device. Therefore, even when the mold is removed from the high-frequency heating device, there is no problem of the mold cracking due to foaming pressure or the like. Therefore, the feature of the present invention is that the solidification step is performed after the mold is removed from the high-frequency heating device. As a result, after heating is completed, the high-frequency heating device can heat another molding material, greatly improving the movability. Then, the mold taken out from the high-frequency heating device is cooled while maintaining the mold clamped state, and the molded product is solidified by cooling or vulcanization hardening.

Thereafter, in a demolding step, the mold is opened and the solidified molded product is taken out.

Functions and Effects of the Invention] In the molding method of the present invention, the mold is placed in a high-frequency heating device while being clamped and held by the clamping member. Therefore, instead of clamping the mold using the electrodes of the high-frequency heating device as in the past, the mold-clamping state can be maintained independently of the high-frequency heating device. Therefore, the solidification step after -C molding can be performed by taking out the mold from the high frequency heating device. This greatly improves the operating rate of the high-frequency heating device and greatly improves productivity.

[Example] Hereinafter, the present invention will be explained in detail using an example shown in the drawings. In this example, the present invention was utilized for molding a protective molding for an automobile.

(Placement Step) A vinyl chloride resin containing a foaming agent was used as the molding material, and the molding material 10 was placed on the mold surface of the lower mold 1 made of silicone resin.

(Mold Clamping Step) Next, the lower mold 1 was placed on the surface of the IS conductive plate 3 made of aluminum, and the conductive plate 2 made of aluminum was placed on the mold surface side of the lower mold 1. Here, a mold surface serving as an upper mold is formed on the surface of the conductive plate 2 facing the mold surface of the lower mold 1, and the lower mold 1 and the conductive plate 2 constitute a mold.

Then press 4 from above the conductive plate 2 to
The conductive plate 2 is pressurized at a pressure of kg/cm2, and while maintaining the pressurized state, an aluminum clamp 5 is used to connect the conductive plate 2 through an insulator 6 made of Teflon or ceramics.
, the lower mold 1 and the conductive plate 3 were sandwiched. When the pressure of the press 4 is released, the lower die 1 is moved to the conductive plate 2.
．． 1~10':4 at 3! The conductive plate 2, the lower mold 1, and the conductive plate 3 are held and fixed together by being held under a pressure of Pkq/C1.

(The conductive plate 2.3 is held and fixed by the molding clamp 5.
And the lower mold 1 is connected to the electrode 7.8 of the high frequency heating device in that state.
As shown in FIG. 2, the electrode 7 is in surface contact with the top surface of the conductive plate 2, and the electrode 8 is in surface contact with the bottom surface of the conductive plate 2 with a predetermined pressure.
A high frequency voltage of W is applied. As a result, the molding material 10
is heated due to the dielectric loss of 1Ω, becomes molten, and the foaming agent foams. Then, a molded body is formed along the inner peripheral surface of the opening 17 formed by the lower surface of the conductive plate 2 and the mold surface of the lower mold 1. Although the clamp 5 is in contact with one electrode 8, there is a distance (h) between the clamp 5 and the other electrode 7 that is at least a distance that does not cause dielectric breakdown, depending on the high frequency voltage.

<Solidification process) After applying a high frequency voltage for 10 to 30 seconds, the conductive plate 2.3 and the lower mold 1 held and fixed by the clamp 5 are heated in that state by high frequency! Taken out from A position, 0.4 ~
Leave to cool for 5 minutes. Thereafter, the clamp 5 is removed, and the solidified molded body is removed from the mold.

According to the above-described molding method of this embodiment, the time the mold is placed in the high-frequency heating device is only 10 to 30 seconds, which is extremely short compared to the conventional method, and the high-frequency heating device can be effectively utilized and movable. rate is improved. In the above embodiment, the upper mold was replaced by the conductive plate 2, but as shown in FIG. Even if the mold 9 and the lower mold 1 are clamped and fixed by the clamp 5, molding can be performed in the same manner.

[Brief explanation of drawings]

Figures 1 and 2 show a molding method according to an embodiment of the present invention. Figure 1 is an explanatory sectional view showing the mold clamping process, and Figure 2 shows the conductive plate and mold after clamping. FIG. 3 is a partial cross-sectional view showing a state in which the device is placed between electrodes of a high-frequency heating device. FIG. 3 is an explanatory sectional view showing another aspect of the embodiment. Figures 4 and 5 show the conventional molding method, Figure 4 is a cross-sectional view showing the state in which the molding material is placed in the lower mold, and Figure 5 is the mold placed in a high-frequency heating device and heated and formed. FIG. 1... Lower mold 2.3.3-... Conductive plate 4... Brace 5... Clamp (clamping member) 6.
...Insulator 7.8.400.500...Electrode 9.
... Upper mold 10 ... Molding material patent applicant
Toyoda Gosei Co., Ltd. Figure 1 Figure 2 Procedural Supplement Voluntary writing) August 9, 1985 Commissioner of the Patent Office Kuro 1) Akio Yu 1, Indication of the incident 1985 Patent Application No. 297395 2, Name of the invention High frequency Method of molding plastics by heating 3, relationship with the amended case Patent applicant Yutaka, 1-1 Nagahata, Ochiai, Kasuga-mura, Nishi-Kasugai-gun, Aichi Prefecture 1)
Synthesis Co., Ltd. Representative: Masao Nemoto 4, Agent: Kodama Building, 3-3-4 Meieki, Nakamura-ku, Nagoya, Aichi Prefecture 450 (tel: 052-583-9720) 5, Invention of the specification subject to amendment Detailed explanation column 6, Contents of amendment (1) In the 4th page, line 14 of the specification, the word "Teflon" will be corrected to "fluorine."that's all

Claims (3)

[Claims] (1) A placing step of placing a molding material in a cavity of a mold in which at least one of the split molds is formed of an insulating material; a clamping step of clamping and holding the mold by clamping members; A molding step in which the clamped and held mold is placed in a high frequency heating device and a high frequency voltage is applied to heat the molding material to form a molded article along the cavity mold surface; A method for molding plastics by high-frequency heating, comprising: a solidification step of taking out the mold and cooling and solidifying the molded object; and a demolding step of opening the mold and taking out the molded object. . (2) A method for molding plastics by high-frequency heating according to claim 1, wherein the holding member is a clamp. (3) A method for molding plastics by high-frequency heating according to claim 1, wherein the clamping member clamps the mold via a conductive plate.