JP2002355879A - Conical screw for twin-screw extruder and extrusion molding method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the conical screw of a twin-screw extruder generating no kneading irregularity even if an extrusion amount is increased, enhancing the physical strength of a molded product and mutually meshed to rotate in different directions, and an extrusion molding method using the screws to increase production quantity. SOLUTION: In the conical screws for the twin-screw extruder having a first stage, which consists of a feed part for successively supplying/feeding a molding compound from the base parts of the screws, a mixing part continued thereto to mix the fed molding compound and a compression part for compressing/melting the molding compound mixed in the mixing part, and a second stage, which consists of a vent part for removing air or a volatile substance from the molten molding compound and a metering part for extruding the molten molding compound in constant quantity, and mutually meshed to be rotated in different directions, a disc having a plurality of axially opened grooves arranged thereto in the circumferential direction thereof is provided in the first stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw for a conical twin-screw extruder which meshes with each other and rotates in different directions, and an extrusion molding method using the screw.

[0002]

2. Description of the Related Art FIG. 3 shows a screw for a conical twin-screw extruder of this type, which meshes with each other and rotates in different directions. The screw 1 shown in FIG. 3 supplies the molding material to the molding material supply port 2 of the barrel 4 and mixes it in a feed section Z1 for conveying the same, followed by a mixing section Z2 for mixing the molding material, and then in a mixing section Z2. Stage B comprising a compression portion Z3 for compressing and melting the molded material, and a vent portion Z for removing volatile substances such as air and moisture from the vent port 3 from the molten molding material.
4 and a second stage A consisting of a metering section Z5 for extruding a certain amount of the molten molding material following the second stage A, and is used for molding general-purpose plastics, especially for molding vinyl chloride resin (hereinafter referred to as PVC) or the like. Used for granulation and pipe molding.

[0003]

[Problems to be Solved by the Invention] PVC as molding material
The case where the pipe is formed by using the method will be described. As shown in FIG. 3, when a conventional screw 1 is used to form a pipe of R-PVC (hard vinyl chloride resin) or the like, the molding material receives a heat generating action at a shear rate received from the screw 1, and the heat generating action occurs. In this case, the molding material dissolves, but at this time, the shear rate becomes partially non-uniform, and the non-uniform heat generation causes uneven temperature in the molding material. Occasionally, a wavy phenomenon in which the surface of the pipe, which is a molded product, is entirely or partially uneven, appears.
If the screw rotation speed is increased to increase the extrusion rate and increase the production rate, the shearing rate of the screw naturally increases, and as a result, the mixing unevenness phenomenon also increases, and the pipe surface undulation phenomenon occurs. Also increases. Therefore, the appearance of the molded pipe becomes poor, so that a good molded article cannot be obtained. However, since the molding material in this case is kneaded at a high shear rate, the characteristic values of the physical strength such as the impact strength and elongation of the molded product such as a pipe are improved. In the actual forming operation, the screw is operated at a screw rotation speed within a range where the appearance of pipes without waving phenomenon is good and the physical strength can be ensured in terms of quality, in which case the screw rotation speed is held low, and the amount of extrusion I have to keep it low. Therefore,
In the R-PVC pipe molding using a conical twin-screw extruder rotating in different directions with each other, the production capacity is limited at a low level because the extrusion rate is kept low.

An object of the present invention is to provide a screw for a conical twin-screw extruder which rotates in different directions without interlocking even when the extrusion amount is increased and which has high physical strength of a molded product,
An object of the present invention is to provide an extrusion molding method using the screw to improve the production amount.

[0005]

In order to achieve the above-mentioned object, the present invention provides a feed section for supplying and conveying a molding material in order from a screw base, a mixing section for mixing the conveyed molding material in succession, A first stage consisting of a compression section that compresses and melts the molding material mixed in the mixing section, a vent section that removes air and volatile substances from the molding material in a molten state, and further a molding section in a molten state. In a screw for a conical twin-screw extruder, which meshes with each other and rotates in different directions, having a second stage composed of a metering portion for extruding a fixed amount, a groove opened in an axial direction in the first stage is formed in a circumferential direction. And a screw for a conical twin-screw extruder, wherein a plurality of arranged disks are provided.

[0006] It is preferable that the conical type twin screw be characterized in that the disk is provided between the mixing section and the compression section.

Then, using the screw for the conical twin screw extruder described above, the molding material is passed through the first stage and the second stage of the screw to mix, compress and compress.
It is more preferable to adopt an extrusion molding method characterized by extruding a fixed amount after melting and removing air and volatile substances.

[0008] Therefore, by inserting a disk having a plurality of circumferentially arranged grooves arranged in the axial direction into the first stage of a screw for a conical twin screw extruder which meshes with each other and rotates in different directions, the molding material is increased. The screw's heat-generating effect on the screw has been improved, and there is no unevenness in kneading. Improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The screw 10 shown in FIG. 1 is similar to the above-described conventional screw in that the first stage B has a barrel 15
A molding material is introduced from the molding material supply port 11 of the above, and a feed part Z1 for conveying the molding material, a mixing part Z2 for mixing the conveyed molding material, and a molding material mixed in the mixing part Z2 are compressed and melted. And a compression portion Z3. The second stage A also has a vent portion Z4 for removing moisture and volatile substances from the molding material melted in the first stage B through the vent port 12, and a molten molding material located therebefore. It consists of a metering part Z5 that pushes out a certain amount.

However, the difference between the screw shape of the present invention and the conventional screw shape is that the mixing portion Z2 of the first stage B portion.
A disk 13 in which a plurality of axially open grooves are arranged in the circumferential direction between the disk 13 and the compression portion Z3. The disk 13 is similar in shape to a gear, but is provided with grooves 14 (14a, 14b, 14c...) For stirring the molding material so as to have a uniform temperature as shown in FIG. When the molding material conveyed from the screw portion of the feed portion Z1 and the mixing portion Z2 passes through the groove 14 of the disk 13, the molding material in the screw groove is stirred and mixed as a whole. Also, the disc 13 has no feed capability itself, and the molding material serves as a barrier to the forward force, so that it acts as a resistance to the forward flow, and a pushing force enough to overcome the resistance is generated in the screw groove. Become
In the screw groove in the feed side direction of the disk 13, the shear force due to the screw rotation is effectively transmitted to the molding material. As a result, the temperature of the molding material is higher than that of the conventional screw. On the other hand, the molding materials conveyed and compressed in the respective screw grooves in the feed direction from the right screw and the left screw disk 13 in the feed direction and subjected to shearing force and having different temperatures are mixed together at the portion immediately after the disk 13. It has the effect of mixing and stirring to make the temperature uniform.
As a result, the molding material that has passed through the disk 13 is ensured to have a uniform molding material without temperature unevenness on average. Although the movement of the molding material theoretically follows the above development,
The specific movement of the molding material coming out of the vicinity of the disk 13 and the groove 14 of the disk 13 has not been verified yet, and the details thereof are not clear. However, according to the embodiment described below, the disk 13 is mounted on the first stage B of the screw 10.
It became clear that by attaching to the part, kneading unevenness was eliminated, and a product that could be increased in extrusion amount could be obtained.

As a result, the molding material passes through the disk 13 to have a more uniform temperature at the first stage B than that of the conventional screw, and the temperature also rises. It is now possible to obtain a molded article that can be increased even if the number is increased. The disc 13 did not have uneven kneading, and the effect of improving physical properties such as impact strength and elongation strength of the molded product was remarkable.

Next, an embodiment in which the performance of the screw of the present invention is compared with that of a conventional screw by R-PVC pipe molding will be described below. 1. Extruder used: Shape TEC-67 (manufactured by Toshiba Machine) 2. 2. Molding material used: R-PVC Molding content: Pipe molding Screw to be used: Screw 10 type (present invention type) Screw 1 type (conventional type) 5. Operation data and operation results Screw shape Rotation speed Extrusion amount Pipe appearance Physical properties (min ^-1 ) (kg / h) (Good / bad) (Elongation%) Screw 10 type 24 291 Good 80-130 Screw 10 type 29 324 Good 180 ~ 203 Screw 1 type 29 324 Evil 80 ~ 130

As described above, the screw 10 of the present invention
The shape is less uneven than conventional screw 1, so there is no waviness on the surface of the product pipe, and even if the screw speed is increased and the amount of extrusion is increased, the appearance of the pipe is good and the physical properties are good. A good pipe was formed.

[0014]

As described above, when the extrusion amount is increased, kneading unevenness occurs, and the appearance of the molded product is deteriorated. No unevenness, high physical strength of molded products,
A screw for a conical twin-screw extruder that meshes with each other and rotates in different directions was provided, and extrusion molding using such a screw to improve production volume became possible.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a screw showing one embodiment of the present invention.

FIG. 2 is an explanatory view of a screw showing one embodiment of the present invention, and is a cross-sectional view taken along line CC of FIG. 1;

FIG. 3 is an explanatory view of a conventional screw.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Screw 11 Molding material supply port 12 Vent port 13 Disk 14 Groove

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F207 KA01 KK13 KK26 KL06 KL42 KL45

Claims (3)

[Claims] 1. A molding material is supplied in order from a screw base.
A feed section to be conveyed, a mixing section that mixes the conveyed molding material subsequently thereto, and a first stage including a compression section that compresses and melts the molding material mixed in the mixing section, A conical twin-screw extruder that rotates in different directions and has a second stage consisting of a vent section that removes air and volatile substances from the molding material and a metering section that further extrudes a certain amount of the molten molding material. A screw for a conical twin-screw extruder, wherein a disk having a plurality of axially open grooves arranged in a circumferential direction is provided in the first stage. 2. The screw for a conical twin screw extruder according to claim 1, wherein said disk is provided between said mixing section and said compression section. 3. Using a screw for a conical twin screw extruder according to claim 1 or 2, the molding material is mixed, compressed and melted by passing through the first stage and the second stage of the screw. After removing air and volatile substances,
An extrusion molding method characterized by extruding a certain amount.