JPH0543499B2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a method of applying heat and pressure to workpieces made of thermoplastic plastic, thereby bonding the workpieces together or imparting a certain shape or pattern to the workpieces. The present invention relates to a thermal processing method.

Prior Art Since thermoplastic plastics soften when the temperature is raised, various heating processing methods such as high-frequency dielectric heating processing and ultrasonic heating processing have been conventionally used to utilize this property. Among them, for example, the high frequency dielectric heating processing method is carried out as follows.

When a plastic film with high high-frequency loss, such as a soft vinyl chloride resin film, is inserted between electrodes and a high-frequency voltage is applied, each molecule that makes up the film causes rotational movement due to the high-frequency electric field.
As a result, friction between adjacent molecules generates heat uniformly throughout the film, and the temperature of the film rises due to heating from within. If pressure is applied to the film in this state, if a pair of films is held between the electrodes, they will adhere to each other, and if a certain pattern is applied to the pressurized object in advance, the film will be bonded with the pressurized object. By applying pressure, the pattern of the pressurized object is transferred to the film.

However, conventional thermal processing methods for plastics, including the above-mentioned high-frequency dielectric heating processing method, have the following disadvantages when the target product is not a simple planar shape but a three-dimensional shape with a curved surface.

In other words, if the target product has a three-dimensional shape with curved surfaces, etc., when applying pressure to the heated plastic with a pressurizer, it is difficult to apply pressure uniformly to the entire plastic, resulting in poor adhesion or uneven transfer. There is an inconvenience that the pattern becomes uneven.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional circumstances, and is a method for thermal processing of plastics, which can uniformly apply pressure to the entire heated plastic to perform good processing. The purpose is to provide the following.

Structure of the Invention That is, the method for thermally processing plastics of the present invention includes laminating the plastic to be processed and a hollow cushion between an upper mold and a lower mold, each having an inner surface shape that does not resemble the surface shape of a product and having a heating function. At the same time as the plastic to be processed is heated by the upper mold and the lower mold, a fluid is injected into the hollow part of the cushion, and the hollow part of the cushion is sandwiched between the upper mold and the lower mold. This method is characterized in that the plastic to be processed is pressed against the inner surface of the mold with uniform pressure by the pressure of the fluid injected into the mold to perform predetermined processing such as patterning.

Embodiments of the Invention The present invention will be described in more detail below with reference to FIG.

FIG. 1 is a diagram showing a state in which plastic is subjected to heat processing by implementing the present invention. In the figure, one of the electrodes 1 and 2, which also serves as an upper mold and a lower mold, is shaped to form the desired product, and also has an unillustrated process that contacts the plastic 3 to be processed. A pattern for transferring the pattern to the plastic 3 to be processed is formed on the pressure surface. That is, as shown in the figure, the plastic 3 to be processed is placed in contact with the electrode 1.
and the electrode 2, and furthermore, a hollow cushion 4 is laminated with the plastic to be processed 3 so as to be in contact with the entire plastic to be processed.
is arranged between the electrode 1 and the plastic to be processed 3, and the electrodes 1 and 2, the cushion 4, and the plastic to be processed 3 are fixed in the above positional relationship. Note that the electrode 1 and the electrode 2 are connected to a power supply device 5, and a hollow portion 4a of the cushion 4 is connected to the electrode 1 and the electrode 2.
is connected to a pressurizing pump (not shown) via an air supply pipe 6.

The electrodes 1 and 2, the plastic to be processed 3 and the cushion 4 are arranged as described above, and the plastic to be processed 3 is thermally processed in the following manner. First, air is sent from a pressure pump (not shown) to the hollow part 4a of the cushion 4 through the air pipe 6, and the cushion 4 uniformly applies pressure to the plastic 3 to be processed. In that case, the reaction force will be received by electrode 1 and electrode 2, so
The plastic to be processed 3 is substantially connected to each electrode 1, 2.
However, the force that presses the plastic to be processed against the electrode 2 is exerted by the cushion 4.
It is equalized by . Next, in this state, electricity is applied to the electrodes 1 and 2 from the power supply device 5, and an alternating frequency voltage is applied to the plastic 3 to be processed between the electrodes 1 and 2. As a result, the plastic 3 to be processed is heated from the inside and softened, and is pressed against the electrode 2 with uniform pressure by the pressing force of the cushion 4, and is formed into a shape that conforms to the electrode 2.
The pattern formed on the image is transferred evenly, resulting in the desired pattern.

In the above embodiments, the heating means for the plastic to be processed is induction heating using alternating frequency voltage, but other means such as ultrasonic heating may also be used, and the fluid supplied to the cushion 4 is limited to air. However, other gases and fluids can be used.

Further, in the above embodiment, the cushion 4 and the electrode 1
Although the cushion 4 is arranged separately from the electrode 1, it is also possible to bond the cushion 4 to the electrode 1 in advance.

Effects of the Invention As described above, according to the plastic thermal processing method of the present invention, by applying even and uniform pressure to the plastic to be processed using a fluid and performing heat processing, it is possible to When joining processed plastics, make sure that no bonding defects occur, and when transferring a certain pattern to the processed plastic, make sure that the transferred pattern is not uneven. Heat processing can be performed.

Further, according to this invention, the cushion is a means to equalize the pressure applied to the plastic to be processed, and since it does not expand greatly, the surface of the cushion hardly stretches, and therefore, when heated,・Adverse effects such as misalignment of the pattern on the surface of the softened plastic are prevented. Furthermore, in this invention, since the plastic to be processed is heated by the upper mold and the lower mold, the pressing force is made uniform by the cushion, and the surface shape of the product is improved. The system can be made more compact and work can be done more quickly.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Electrode, 2... Electrode, 3... Plastic to be processed, 4... Cushion, 5... Power supply device, 6
...Air pipe.

Claims (1)

[Claims] 1. A plastic to be processed and a hollow cushion are stacked and arranged between an upper mold and a lower mold, each having an inner surface shape similar to that of a product and having a heating function, and the plastic to be processed is placed between the upper mold and the lower mold. A fluid is injected into the hollow part of the cushion at the same time as the plastic is heated by the mold, and the pressure of the fluid injected into the hollow part of the cushion is applied to the plastic to be processed, so that the plastic is heated by the upper and lower molds. A method of thermal processing of plastics characterized by pressing one inner surface with uniform pressure.