JPS62184829A - Vent type extruder - Google Patents

Abstract

PURPOSE:To make the amount of molten resin overflowing a venting hole as small as possible and prevent the resin overflowed by any chance from being sucked by a vacuum pump by a structure wherein the outer end of the venting hole is connected to a position higher than the bottom lid of an airtight vacuum chamber, in the upper part of which a connecting hole to the vacuum pump is provided at a position far apart from the joint of the venting hole. CONSTITUTION:Venting of pellets, filling material or the like in semi-molten state is done by passing along a venting hole 15 part when carried in the direction of the axes of a cylinder 11 and of a screw shaft 12 by means of the screw shaft 12. At that time, some part of resin A or of the filling material in molten or semi-molten state overflows in the venting hole 15. However, because the venting hole 15 inclines, the gravitational force acts on the resin or filling material in the venting hole 15 as a force to pull the resin of filling material back into the cylinder 11. In addition, because the venting hole 15 inclines in the forward direction of rotation, the resin or filling material in the venting hole is again scratched off by the flight 14 of the screw shaft 12 as the screw shaft 12 rotates. Consequently, almost all the resin or filling material in the venting hole is brought back into the cylinder 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to be used] The present invention relates to a vent-type extruder in which gas generated in a cylinder is vented midway through the cylinder in a synthetic resin extruder.

[Prior art]

Conventionally, a vent hole for degassing is provided perpendicularly through the cylinder at the upper surface of the cylinder where the raw material pellets are heated and starts to melt, and is directly connected to a vacuum pump.

〔problem〕

However, a portion of the molten resin leaks out from the vent hole, and the molten resin is sucked into the vacuum pump, often making it difficult to operate the vacuum pump. Either the vacuum pump must be stopped for cleaning, or a spare vacuum pump must be installed and switched over from time to time for cleaning.

The purpose of this invention is to minimize the amount of bath molten resin leaking out of the vent holes as described above, and to prevent it from being sucked into the vacuum pump even if the resin leaks out of the vent hole.

[Means for resolving problems]

In this invention, when the screw shaft rotates, a vent hole is provided in the side surface of the cylinder on the side where the circumferential surface descends, and this vent hole is located higher toward the outer end, and the screw shaft rotates in the forward direction with respect to the radial direction of the cylinder. The outer end of this vent hole is connected to a position higher than the bottom cover of the airtight vacuum chamber, the bottom cover of which can be opened and closed, and the vent hole is provided at an upper part of the airtight vacuum chamber. The problem was solved by using a vent type extruder, which is characterized by having a vacuum pump connection hole provided at a position remote from the hole connection part.

[For production]

In this invention, which is configured like a constriction, a vacuum pump is connected to the vacuum pump connection hole at the top of the airtight decompression chamber, and while operating the vacuum pump, pellets or pellets are collected from the supply port of the cylinder as in a normal vent-type extruder. When the extruder is operated by supplying a mixture of filler and filler, the gas generated in the cylinder is suctioned and removed by the vacuum pump through the inclined vent hole and the airtight vacuum chamber.

In addition, since the pressure is reduced near the inner end surface of the vent hole, some of the molten resin or the mixture of this and additives such as fillers overflows into the vent hole. Since the outer end is tilted upward in the forward rotational direction of the screw shaft, most of it is rolled up into the cylinder again by the rotation of the screw shaft and transported downstream of the cylinder.

However, a small amount of the bath-molten or semi-molten resin remains on the inner wall surface of the vent hole, and the amount increases with the passage of time, and eventually begins to wet the inside of the airtight vacuum chamber from the vent hole. This allows the gas to be inhaled and gM! am
The fat is separated and only the gas is exhausted from the top of the airtight vacuum chamber by a vacuum pump.

The molten resin then solidifies when it comes into contact with the wall surface and bottom cover of the airtight vacuum chamber. When a sufficient amount of wet resin has accumulated in the airtight vacuum chamber, temporarily stop the vacuum pump, bring the pressure inside the airtight vacuum to atmospheric pressure, and open the bottom cover.
Remove the resin inside, close the bottom cover again, and restart the vacuum pump.

〔effect〕

In the same way, since the device of the present invention is configured and operates as described above, the wet field is completely separated from the gas through the vent hole, so the bath melt resin is sucked into the vacuum pump, making this operation impossible. In addition, the resin accumulated in the airtight vacuum chamber can be easily removed by opening the bottom cover, which significantly improves the operating efficiency of the extruder compared to conventional models.
Production costs can be reduced.

[Embodiment]

In order to further deepen the understanding of the present invention, a description will now be given based on representative embodiments shown in the drawings.

In the figure, reference numeral 10 denotes a vent-type presser, and its cylinder 11 and screw shaft 12 are installed horizontally on a base 13. 14 is a flight of a screw shaft, the screw shaft 12 rotates in the direction of the arrow, and a vent hole 15 for degassing is provided on the side surface of the cylinder 11 on the side where the circumferential surface descends; In the illustrated example, the inclination angle of the hole 15 seems to be at a higher position at the outer end by 45 degrees with respect to the vertical line, and also with respect to the radial direction of the cylinder 11 and in the forward rotation direction of the screw shaft 12. It is installed at a 45° inclination.

The angle of inclination with respect to the radial direction is not particularly limited as long as it is between 30° and 90°, that is, in the tangential direction.

The outer end of the vent hole 15 is connected to the middle and upper part of the airtight decompression chamber 16, and the connection port 17 is provided with an automatic closing valve 18. A cooling coil 20 is attached to the outer surface of the side wall 19 of the airtight vacuum chamber 16 . 21
is a bottom cover, and a cooling coil 22 is also attached to the outer surface of the bottom cover, and the side wall 19 and the inner wall surface of the bottom cover 21 serve as cooling heat exchange surfaces. The bottom cover 21 can be opened and closed by a suitable fastener 23 such as a bolt, and can be attached to the airtight decompression chamber 1G.
It is attached to the bottom of the side wall 19.

Reference numeral 24 designates an upper lid, a vacuum pump connection port formed by a transparent plate and provided at a position away from the connection port 17 of 5, and 26 a vacuum pump.

[Operations and effects of embodiments]

In the embodiment described above, when the entire apparatus is operated, the pellets and filler in a semi-bath molten state are passed through the vent hole 15 part by the screw shaft 12 into the cylinder 11 and the screw shaft 12.
When conveyed in the axial direction, gas is degassed and passed through, and some of the melted or half-bath melted resin A-? The filling material is wetted in the vent hole 15, but since the vent hole 15 is inclined as shown in the figure, the mB8 and the filling material in the vent hole 15 are returned to the cylinder 11 due to the action of gravity. As this vent hole 15 is inclined in the forward rotational direction of the screw shaft as shown in the figure, as the screw shaft 120 rotates, the flight 14 scrapes the vent hole 15 again, and most of it is returned to the cylinder 11. .

However, while remaining in the vent hole 15, the bath melts and climbs onto the molten or semi-bath molten resin adhering to the inner wall surface of the vent hole 15, and finally pushes open the self-closing valve 18. A wet field is placed in the airtight vacuum chamber 16, and this side wall 19
Since the bottom cover 21 is cooled by the cooling coils 20 and 22, the molten resin is solidified and accumulated in the airtight vacuum chamber 16.

In this way, the wetted molten resin flows to the lower blade and is separated from the gas, and only the generated gas is sucked and removed by the vacuum pump 26.

In this way, when it is seen through the upper lid 24 that the amount of resin in the airtight vacuum chamber 16 has accumulated near the vent hole connection port 17, the vacuum pump 26 is temporarily stopped and the pressure inside the airtight vacuum chamber 16 is reduced. When the pressure is equalized to atmospheric pressure, loosen the fastener 23, open the bottom cover 21, remove the solidified resin from the airtight vacuum chamber 16, and open the bottom cover 21 again.
Close and tightly seal with the fastener 23, and restart the operation of the vacuum pump.

Therefore, in this embodiment, since the resin is solidified in the airtight decompression chamber 16, the resin removal operation becomes easy, and the reuse can be performed with less atmospheric contamination. Also, since the top lid 24 is transparent, it is easy to monitor the internal condition.
When cleaning the inside, opening the upper and lower lids 24 and 21 makes the task extremely easy.

When the inclination angle α of the vent hole 15 is within the above-mentioned range with respect to the radial direction of the cylinder, the wet rice in the vent hole 15 tends to return to the inside of the cylinder, and in other cases, the amount of wet rice increases.

Furthermore, when the angle of inclination of the vent hole 15 to the vertical is about 45 degrees, installation with the airtight decompression chamber 16 is easy and the amount of wetted bath melt resin is small.

It is also possible to use two airtight decompression chambers 16 and provide them so that they can be connected by sliding them alternately to the connection slot 17 position in case they become full and can be replaced when removing the resin inside. The present invention is the same, and by performing K in this manner, the operating efficiency of the extruder can be further improved.

[Brief explanation of drawings]

The drawing is a partially longitudinal front view showing a typical embodiment of the invention. Main symbols in the diagram 10... 3 press tf machines, 11...
・Cylinder, 12...Screw shaft, 15・
...Vent hole, 16...Airtight vacuum chamber, 21...Bottom cover, 25...Vacuum pump connection hole.

Claims (1)

[Claims] 1) A vent hole is provided in the side of the cylinder on which the circumferential surface descends when the screw shaft rotates, and the vent hole is located higher toward the outer end, and the screw shaft is lowered in the radial direction of the cylinder. The outer end of this vent hole is connected to a position higher than the bottom cover of the airtight decompression chamber whose bottom cover can be opened and closed, and the outer end of this vent hole is connected to a position higher than the bottom cover of the airtight vacuum chamber whose bottom cover can be opened and closed. A vent-type extruder characterized in that a vacuum pump connection hole is provided at a position remote from the vent hole connection portion. 2) The vent type extruder according to claim 1, wherein at least a part of the side wall surface of the airtight vacuum chamber is a heat exchange surface for cooling. 3) The top surface of the bottom lid of the airtight vacuum chamber is a cooling heat exchange surface. The vented extruder according to claim 1, characterized in that the vented extruder is provided as a heat exchange surface for use. 4) The vent-type extruder according to claim 1, wherein the inclination angle of the vent hole is 30° to 90° with respect to the radial direction.