JPH0230847B2 - KANETSUSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heating device for preheating tablets used in transfer molding.

[Background technology]

In the transfer molding method, it is necessary to heat the tablet (resin lump) in advance, which is placed in a pot and compressed by a plunger.For this reason, the inventor developed and used a heating device shown in Fig. 1. There is. That is, this device consists of a lower electrode 3 consisting of a pair of rollers 1 and 2 arranged in parallel, and an upper electrode 4 supported above the lower electrode 3 in parallel with the lower electrode 3.
Then, the cylindrical tablet 5 is connected to the lower electrode 3.
By placing the tablet 5 on top and rotating the rollers 1 and 2, the upper and lower electrodes 3,
If high frequency power 6 is applied between 4 and 4, the tablet 5 will be heated by dielectric heating. The rotation of the tablet 5 causes the tablet to be heated uniformly in the circumferential direction.

However, in this heating device, as shown in the figure, the electric field between the tablet 5 and the upper electrode 4 tends to concentrate at both ends of the tablet 5 due to the characteristics of the electric field. will be heated significantly.

For this purpose, this preheated tablet 5 is loaded into the pot 8 of the transfer molding device 7 as shown in FIG. 2 (two tablets are loaded in the figure) and compressed by the plunger 9. Then, both ends, which are heated significantly, are deformed first, and this deformation causes the air a around the middle of the tablet to be confined to both ends. Therefore, if molding is performed in this state, air will be forced into a cavity not shown in the drawings, resulting in bubble defects in the molded product.

[Purpose of the invention]

The object of the present invention is to be able to heat the center of the tablet to a higher temperature than the edges, so that when the tablet is compressed in the pot, the tablet is deformed from the center, effectively releasing air around the tablet and sealing it in the resin. An object of the present invention is to provide a heating device that can prevent such problems.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, the strength of the electric field generated between the lower electrode and the upper electrode is made to differ in the length direction of the electric field, and the electric field strength at the center of the tablet is made larger than that at both ends. It can be heated to a higher temperature than both ends.

Embodiment 1 FIG. 3 shows an embodiment of the present invention. In particular, this embodiment shows a heating device for loading two tablets in series in a pot of a transfer molding device and compressing them integrally. It shows. In the figure, the lower electrode 11 consists of two rollers 12 and 13 arranged in parallel to each other, and the rotating shafts 14 and 15 of each roller 12 and 13 are supported by bearings 16 and 17, and a plurality of gears 18 , 19, 20 is fixedly installed, and is rotated by a motor 22. Two cylindrical tablets 2 are placed on these rollers 12 and 13.
3 and 24 can be placed in series, and the rollers 12 and 1 can be placed in series.
3, each tablet 23, 24 is rotated. Note that the tablets 23 and 24 are fixed in their axial positions (lengthwise positions) on the rollers 12 and 13, and for this purpose, for example, stoppers 25 and 25 as shown are provided on the lower electrode 11. attached.

On the other hand, an upper electrode 26 is disposed above the lower electrode 11 in a substantially parallel manner and is supported by a support member (not shown). This upper electrode 26 consists of a roof-shaped main electrode 27 extending in the length direction and an auxiliary electrode 28 fixedly installed in the center of this main electrode 27, and a high frequency power source 29 is connected between it and the lower electrode 11. Connected. The auxiliary electrode 28 has a shape in which its downward protrusion length is changed in the length direction of the electrode, and the portion corresponding to the collision position of the tablets 23 and 24, in other words, the tablets 23 and 24 are
Considering the tablet, the protruding length of the portion 28a corresponding to the central portion is also the largest, and both ends 28b,
It has a shape that gradually decreases toward 28b.

According to the above configuration, when the rollers 12 and 13 are rotated by the motor 22, the tablets 23 and 24 are rotated, and when high frequency power is applied between the upper and lower electrodes 26 and 11, the upper electrode 26 and the lower electrode 11 are rotated. ,
Furthermore, the upper electrode 26 and the tablets 23, 24
An electric field is generated between them, and the tablets 23 and 24 are heated uniformly in the circumferential direction by the dielectric heating.
At this time, the auxiliary electrode 28 and the tablet 2
3 and 24, the electric field strength at the central portion 28a having a large protrusion length is higher than that at both end portions 28b and 28b.
Since the electric field strength of tablet 23,
24, the central portion in the combined length direction is heated more significantly than both ends, and the central portion is heated to a high temperature.

Therefore, the tablets 23 and 24 heated in this way are treated as one tablet and placed in the pot 8 of the transfer molding machine as shown in FIG.
When the tablets 23 and 24 are loaded into the tablet and compressed by the plunger 9, the central portion of the tablets 23, 24 is first deformed, and then the both ends are deformed, as shown in the figure. Therefore, the air a existing on the inner surface of the pot 8 and the outer periphery of the tablets 23 and 24 is expelled upward and downward of the pot 8 as shown by the arrows in the figure, thereby reliably preventing air from being trapped in the resin. . That is, a good molded product without bubbles can be manufactured.

Embodiment 2 FIG. 5 shows a second embodiment of the present invention, in which the upper electrode 26A is different. Therefore, the first
Components that are the same as those in the embodiment are given the same reference numerals and explanations will be omitted. In this embodiment, the upper electrode 26A is formed in the shape of a ship's bottom, and the amount of downward protrusion of its bottom edge 30 is varied in the length direction, so that a portion corresponding to the combined center of the tablets 23 and 24 is replaced with another portion ( (corresponding parts at both ends).

Therefore, according to this embodiment, the upper electrode 26A
The strength of the electric field generated between the lower electrode 11 and the lower electrode 11 already differs in the length direction, and the strength in the central part is greater than in other parts. As a result, the center of the tablets 23, 24 is heated to a higher temperature than both ends, as in the previous example, to prevent air from being trapped and bubbles from forming in the transfer mold.

Embodiment 3 FIG. 6 shows a third embodiment of the present invention, and the figure schematically shows the main parts. In the figure, the lower electrode 3
1 is composed of rollers as in each of the above examples, but
At this time, the rollers are constructed by pairing a plurality of short rollers 32 made of a conductive material in series with an insulating material 33 interposed therebetween. On the other hand, the upper electrode 34 also has a structure in which conductive members 35 and insulating members 36 are alternately arranged in series. Each pair is formed by a short roller 33 and a conductive member 35 that are vertically opposed to each other in the upper and lower electrodes 34 and 31, and independent high frequency Electric power 37 can be applied. Also, at this time, a high power 37a is applied between the short roller 33a and the conductive member 35a facing the central part of the tablets 23 and 24, and a low power is applied to the parts facing both ends. Configure.

According to this configuration, the electric field strength at the center of the tablets 23, 24 is greater than the electric field strength at both ends, so that the center of the tablets 23, 24 is heated to a higher temperature than at both ends. It turns out. It goes without saying that this prevents air from being trapped in the transfer mold, thereby preventing air bubbles.

It should be noted that the lower electrode 31 can also be connected to a common, so in this case it may be configured as an integral roller.

〔effect〕

(1) Since the protrusion length of the auxiliary electrode of the upper electrode is maximized at the center, the electric field strength at the center of the tablet is maximized, thereby making it possible to heat the center of the tablet to a higher temperature than both ends.

(2) Since the upper electrode itself is configured so that the amount of protrusion is maximum at the center, the electric field strength at the center of the tablet can be maximized in the same way, and the center of the tablet can be heated to a high temperature.

(3) At least the upper electrode is divided in the length direction so that an electric field can be applied independently to each part, and the electric field is maximized at the center of the tablet. can also be heated to high temperatures.

(4) As described in (1), (2), and (3) above, since the center of the tablet is heated to a higher temperature than both ends, air can be effectively expelled during compression inside the transfer mold pot. This prevents air from being trapped in the resin and prevents air bubbles from forming in the molded product.

Although the invention made by the present inventor has been specifically explained based on the examples above, the present invention is not limited to the above examples, and it is understood that various changes can be made without departing from the gist of the invention. Needless to say. For example, when heating one or more tablets, the distribution of electric field strength can be adjusted according to the entire length of the tablets.
Further, the shape of the upper electrode may be made into a shape other than the illustrated example.

[Application field]

The above explanation has mainly been about the application of the invention made by the present inventor to a preheating device for tablets in a transfer molding machine, which is the background field of application, but the present invention is not limited to this. It can also be applied as a heating device for articles that require heating the center of the article to a higher temperature than the edges.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view of a device that has been previously developed and implemented, Fig. 2 is a sectional view of the pot to explain the problems, Fig. 3 is a perspective view of the first embodiment of the present invention, and Fig. 4
The figure is a cross-sectional view of the pot to explain the effect.
The figure is a schematic perspective view of the second embodiment, and FIG. 6 is a schematic side view of main parts of the third embodiment. 11... Lower electrode, 12, 13... Roller, 2
3, 24... Tablet, 26, 27A... Upper electrode, 27... Main electrode, 28... Auxiliary electrode, 29
... High frequency power, 30 ... Bottom edge, 31 ... Lower electrode, 32 ... Short roller, 34 ... Upper electrode, 35
...Conductive member, 37...High frequency power.

Claims (1)

[Scope of Claims] 1. A device configured such that high frequency power can be supplied between a lower electrode on which an object to be heated is placed and an upper electrode placed opposite thereto, and the length of the object to be heated is A heating device characterized in that the upper electrode is configured such that the electric field strength at the center in the direction is greater than the electric field strength at both ends. 2. The heating device according to claim 1, wherein an auxiliary electrode is provided on the upper electrode, and the auxiliary electrode is configured such that its protrusion length toward the lower electrode is maximized at the center. 3. Claim 1, in which the bottom edge of the upper electrode is configured to protrude furthest toward the lower electrode at the central portion.
Heating device as described in section. 4. The heating device according to claim 1, wherein the upper electrode is divided in the length direction so that electric power can be applied independently to each part, and the electric power is set to the maximum in a portion corresponding to the central portion. 5. The heating device according to any one of claims 1 to 4, wherein the object to be heated is a tablet for transfer molding.