JPH0538910Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a vent device for a twin-screw kneading extruder.

(Prior art) A twin-screw kneading extruder used for extrusion molding of thermoplastic resin has a vent opening in a barrel into which a screw is inserted, and the vacuum pressure releases scattered plastic pieces, powder, or monomer. They are now inhaling flying debris.

By the way, the vent port of the conventional twin-screw kneading extruder is
As shown in FIG. 3, the vent port 1 is opened upward on the upper surface of the barrel 2, so that when the vacuum vent is pulled, plastic pieces, powder, or monomer particles 3 scattered by the vacuum pressure are released. Once it adheres to the inner wall 1a of the vent port 1 and stays there, it is heated by the heat of the barrel 2 and becomes a burnt material, and then it falls back into the screws 4, 4 due to gravity, and this is heated by the screws 4, 4. It will be extruded.

As a result, this is mixed into products, causing one lot of defective products.

In order to prevent this, the vent port 1 is cleaned once or several times a day, but if this cleaning is done while the extruder is running, the products extruded during that time may become defective. becomes unavoidable.

Therefore, although it is possible to prevent vent build-up by opening the vent port upward, it is difficult to prevent the vent build-up from entering the screw again, and there is no way to simultaneously satisfy these two preventive measures. Nakatsuta.

The present invention focuses on the drawbacks of the prior art described above, and
The present invention provides a vent device for a twin-screw kneading extruder having a vent port structure that can solve two preventive measures at the same time with one component.

(Structure of the invention) In order to achieve the above object, the present invention has a vent opening that opens in a direction perpendicular to the screw axis at a position horizontally above or below the axis of the screw of a twin-screw kneading extruder; On the rear side in the direction of rotation of the screw that is inserted into the vent port and rotates within the vent port, there is an inner sloped surface that slopes upwardly following the inner peripheral surface of the barrel, and an outer sloped surface that slopes downwardly in the opposite direction to the sloped surface on the back surface thereof. The vent block is fixed to the barrel to form a vent block.

(Function) The measure to prevent vent build-up is based on the ``inner inclined surface that slopes up following the inner peripheral surface of the barrel on the rear side of the vent opening in the direction of screw rotation.'' By configuring the inner inclined surface in this way, The molten resin transferred by the rotation of the screw is transferred into the barrel from the wide cross-sectional area of the opening to the narrow side, creating a wedge effect. This makes it difficult for the resin to flow, and serves as a measure to prevent vent build-up. In addition, as a measure to prevent the vented material from entering the screw again, an outer sloped surface that slopes downward in the opposite direction to the sloped surface is formed on the back side of the screw, so that there is no accumulation of material during suction. After the scattered objects stay on the inner wall surface of the vent port for a long time, the weight prevents them from entering the screw side where they fall.

(Embodiment) The present invention will be described below with reference to the embodiment shown in FIGS. 1 and 2, using the same reference numerals for parts common to FIG. 3.

As shown in FIG. 1, which shows a longitudinal section of an example of a vent device for a twin-screw kneading extruder according to the present invention, a vent port 1 is provided on one side of a barrel 2 into which parallel two-screw screws 4, 4 are inserted in parallel. is opened horizontally. A vent block 5 and a vent port 6 are connected to the outside of the vent port 1, and their outer ends are sealed so that suction can be drawn in the direction of the arrow.

In addition, as shown in Figure 2, the screw 4,
Between the horizontal line A and B passing through the axis of 4, this horizontal line A
- It can be opened within a range of 180° below B.

In either case, inside the vent port 1, there is an inner inclined surface 5a that slopes upwardly following the inner circumferential surface of the barrel 2 on the rear side in the direction of rotation of the screw, and an inner inclined surface 5a that slopes downwardly in the opposite direction to the inclined surface 5a on the back surface thereof. The insert portion 5c of the vent block 5 is inserted, and the vent block 5 is fixed to the barrel 2.

Therefore, the scattered objects sucked and scattered from the vent port 1 mainly adhere to the outer sloped surface 5b, but since this sloped surface 5b slopes downwardly toward the outside, they fall into the barrel 2 again. Therefore, flying objects do not enter the screws 4, 4 side, and are prevented from being mixed into the product.

[Effect of the invention]

As explained above, the present invention opens the vent opening in the barrel of a twin-screw kneading extruder in a direction perpendicular to the screw shaft at a position above or below the horizontal line passing through the axis of the screw shaft. , and by providing an inner inclined surface that slopes upward following the inner peripheral surface of the barrel on the rear side of the vent port in the direction of screw rotation, the molten resin transferred by the rotation of the screw flows through the opening with a wide cross-sectional area. Since the resin is transferred into the barrel from the narrow surface to the narrow surface with a wedge effect, it becomes difficult for the resin to flow in the lateral direction of the vent port as the screw rotates, thereby preventing vent build-up. In addition, by providing an outer inclined surface that slopes downward in the opposite direction to the inner inclined surface on the back side of the inner inclined surface, there is no possibility of accumulation, and the particles scattered during suction will not stay on the inner wall of the vent port for a long time. After staying there, the weight prevents it from falling and entering the screen. These prevent deposits from entering the product, thereby reliably preventing the production of defective products. Further, there are various effects such as the fact that the debris that comes off when cleaning the vent port does not enter the screw, making it possible to clean it at any time even during operation.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, FIG. 2 is an explanatory view showing the installation range of the vent port in the present invention, and FIG. 3 is an explanatory view of the prior art. 1...Vent port, 2...Barrel, 4...Screw, 5...Vent block, 5a...Inner inclined surface, 5b...Outer inclined surface.

Claims (1)

[Scope of utility model registration request] A vent opening perpendicular to the screw axis at a position above or below the horizontal line passing through the screw axis of the twin-screw kneading extruder, and a rotating direction of the screw inserted into the vent opening and rotating within the vent opening. It consists of a vent block fixed to the barrel to form an inner inclined surface on the rear side that slopes upward following the inner circumferential surface of the barrel, and an outer inclined surface on the back side that slopes downward in the opposite direction to the inclined surface. A vent device for a twin-screw kneading extruder characterized by the following.