JP2018196970A - Extruder - Google Patents

Abstract

In an extruder having a cylinder provided with a heater and a screw housed in the cylinder, it is possible to achieve both suppression of unmelted resin pellets and shortening of the screw length. The height of the groove 23 of the screw 20 near the material supply port 11 on the base end side of the cylinder 10 is set to a height corresponding to the size of the resin pellet so that the resin pellet R overlaps in the groove 23. And the heat can be supplied to the resin pellet R at a position near the inner wall surface 10b of the cylinder 10. Furthermore, by reducing the height of the groove 23 of the screw 20 from the vicinity of the material supply port 11 on the proximal end side of the cylinder 10 toward the extrusion port 12 on the distal end portion, the resin pellet that becomes smaller according to the molten state Since the distance between the inner wall surface 10b of the cylinder 10 and the resin pellet R can be kept short corresponding to R, the resin is sufficiently melted at the tip of the cylinder 10. [Selection] Figure 1

Description

  The present invention relates to an extruder used for resin molding.

  The extruder used for resin molding includes a cylinder equipped with a heater and a screw housed in the cylinder, and melts and kneads resin pellets made of thermoplastic resin by heating with the heater and rotation of the screw. There is known an extruder that is in a state and extrudes the molten resin from an extrusion port (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-166428

  By the way, in an extruder, when resin pellets are filled in layers formed in the groove formed between the flights of the screw, resin pellets far from the inner wall surface of the cylinder (resin pellets accumulated at the bottom of the groove) ), It is difficult for heat to be transferred to the resin pellets. In order to eliminate all undissolved resin pellets and make all the resin pellets into a molten state, it is necessary to secure a certain screw length, and there is concern about an increase in the size of mechanical equipment.

  The present invention has been made in consideration of such a situation, and in an extruder provided with a cylinder provided with a heater and a screw accommodated in the cylinder, it is possible to suppress unmelted resin pellets, An object is to provide a structure capable of achieving both shortening of length.

  The present invention includes a cylinder provided with a heater, a spiral groove formed on the outer periphery, a screw rotatably accommodated inside the cylinder, and a material supply port provided on the base end side of the cylinder. An extrusion port provided at the tip of the cylinder, and the resin pellets that are introduced into the cylinder from the material supply port are melted and kneaded by the heater and the screw to be in a molten state, and the molten resin is In the extruder for extruding from the extrusion port, the height of the groove of the screw near the material supply port is a height corresponding to the size of the resin pellet before melting, and the height of the groove of the screw is the cylinder. It is comprised so that it may become low as it goes to the said extrusion port from the said material supply port vicinity.

  According to the present invention, since the height of the groove of the screw near the material supply port is a height corresponding to the size of the resin pellet before melting, it is possible to suppress the overlap of the resin pellet in the groove, Heat can be supplied to the resin pellets at a position close to the inner wall surface of the cylinder. Thereby, the resin pellet is easily melted. Furthermore, since the height of the screw groove is reduced as it goes from the vicinity of the material supply port to the extrusion port, the distance between the cylinder inner wall surface and the resin pellet corresponding to the resin pellet that becomes smaller depending on the molten state Can be kept close to each other, so that the resin is sufficiently melted at the tip of the cylinder.

  As described above, according to the present invention, the resin pellets can be efficiently melted, so that the resin pellets can be prevented from being melted even if the screw length is shortened.

  According to the present invention, in an extruder provided with a cylinder provided with a heater and a screw housed inside the cylinder, it is possible to achieve both suppression of unmelted resin pellets and shortening of the screw length. It becomes possible.

It is sectional drawing which shows schematic structure of the extruder to which this invention is applied. It is a side view of the screw used for the extruder of FIG. 3A is an enlarged view corresponding to part A in FIG. 2, FIG. 3B is an enlarged view corresponding to part B in FIG. 2, and FIG. 3C is an enlarged view corresponding to part C in FIG. It is. It is a side view which shows the prior art example of a screw. 5D is an enlarged view corresponding to the D portion in FIG. 4, FIG. 5E is an enlarged view corresponding to the E portion in FIG. 4, and FIG. 5F is an enlarged view corresponding to the F portion in FIG. It is.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an extruder 1 to which the present invention is applied. FIG. 2 is a side view of the screw 20 used in the extruder 1 of FIG.

  The extruder 1 includes a cylinder 10, a screw 20, a heater 30, a hopper 40, a rotation mechanism 50, and the like.

  The cylinder 10 is a cylindrical member, and a cylindrical space 10a is formed therein. A material supply port 11 that opens upward is provided on the base end side of the cylinder 10. An extrusion port 12 is provided at the tip of the cylinder 10.

  A screw 20 is accommodated in the cylinder 10 (in the cylindrical space 10a). A flight 22 is spirally formed on the outer periphery of the screw shaft 21 of the screw 20. The spiral flight 22 forms a spiral groove 23 on the outer periphery of the screw 20.

  The screw 20 can rotate inside the cylinder 10 and can move forward and backward. The screw 20 is rotated inside the cylinder 10 by a rotation mechanism 50 having a motor or the like. The screw 20 is moved forward and backward by an advance / retreat mechanism (not shown).

  A heater 30 is wound around the outer periphery of the cylinder 10. The heater 30 is driven and controlled by, for example, a heater controller (not shown), and the temperature inside the cylinder 10 can be controlled to a temperature at which the resin pellet R can be melted by the driving control of the heater 30.

  A hopper 40 is disposed above the material supply port 11. The inside of the hopper 40 communicates with the inside of the cylinder 10 through the material supply port 11. The hopper 40 is filled with resin pellets R made of a thermoplastic resin.

  In the above extruder 1, the resin pellet R filled in the hopper 40 is introduced into the cylinder 10 through the material supply port 11 of the cylinder 10. The resin pellet R put into the cylinder 10 is melted and kneaded by heat from the inner wall surface 10b of the cylinder 10 (heating by the heater 30) and rotation of the screw 20 to be in a molten state, and the molten resin is extruded from the extrusion port 12. . The molten resin extruded from the extrusion port 12 is filled into a cavity in an injection mold (not shown), and the resin molding is manufactured by cooling the molten resin in the cavity.

-Feature part-
Next, the characteristic part of the extruder 1 of this embodiment is demonstrated with reference to FIGS.

  3A is an enlarged view corresponding to part A in FIG. 2, FIG. 3B is an enlarged view corresponding to part B in FIG. 2, and FIG. 3C corresponds to part C in FIG. It is an enlarged view.

  In the extruder 1 of this embodiment, as shown in FIG. 3A, the height h of the groove 23 of the screw 20 near the material supply port 11 of the cylinder 10 corresponds to the size of the resin pellet R before melting. The height is to be. Further, as shown in FIGS. 3A to 3C, the height of the groove 23 of the screw 20 is configured to become lower from the vicinity of the material supply port 11 of the cylinder 10 toward the extrusion port 12. There is a feature in that. The outer diameter of the flight 22 of the screw 20 is constant in the axial direction.

  By forming the groove 23 of the screw 20 in such a shape, the undissolved residue of the resin pellet R can be suppressed even if the length of the screw 20 is shortened. This will be described below.

  First, in the screw 120 shown in FIG. 4 (conventional example), as shown in FIG. 5D (enlarged view corresponding to part D in FIG. 4), the resin pellet R is placed in the groove 123 between the flights 122 of the screw 120. Is filled in a state where a plurality of layers are stacked, heat is unlikely to be transmitted to the resin pellet R (resin pellet R accumulated at the bottom of the groove 123) far from the inner wall surface 110b of the cylinder 110. Further, at the central portion in the axial direction of the screw 120, as shown in FIG. 5E (enlarged view corresponding to the E portion in FIG. 4), heat is transferred to the resin pellet R far from the inner wall surface 110b of the cylinder 110. It becomes difficult to melt the resin pellet R. Then, at the tip of the screw 120, as shown in FIG. 5F (enlarged view corresponding to the F portion in FIG. 4), the height of the groove 123 of the screw 120 is high and the volume is large, so that the resin pellet R It takes time to completely dissolve. For this reason, in order to eliminate the undissolved residue of the resin pellet R and to make all the resin pellets R into a molten state, it is necessary to secure the length of the screw 120 to some extent, and there is a concern about an increase in the size of the mechanical equipment. If the length of the screw 120 is short and the resin pellet R remains undissolved, there is a concern that molding failure due to the undissolved resin (unmelted resin) may occur.

  In contrast, in this embodiment, as shown in FIG. 3A, the height h of the groove 23 of the screw 20 near the material supply port 11 of the cylinder 10 corresponds to the size of the resin pellet R before melting. Therefore, the overlap of the resin pellets R in the groove 23 can be suppressed. Thereby, heat can be supplied to all the resin pellets R at a position close to the inner wall surface 10 b of the cylinder 10.

  Further, since the height of the groove 23 of the screw 20 is configured to become lower from the vicinity of the material supply port 11 of the cylinder 10 toward the extrusion port 12, the central portion in the axial direction of the screw 20 is shown in FIG. As shown in (B), the distance between the inner wall surface 10b of the cylinder 10 and the resin pellet R can be kept close. Furthermore, since the resin pellet R in the groove 23 (resin pellet R reduced in accordance with the molten state) is crushed by the inner wall surface 10b of the cylinder 10, the heat transfer area from the inner wall surface 10b increases. Thereby, melting of the resin pellet R is accelerated. And at the front-end | tip part of the screw 20, since the height of the groove | channel 23 is low and the volume of the groove | channel 23 is small as shown in FIG.3 (C), the resin pellet R will fully fuse | melt.

  Thus, according to the extruder 1 of this embodiment, since the resin pellet R can be efficiently melted, the undissolved residue of the resin pellet R is suppressed and the length of the screw 20 is shortened. It becomes possible to achieve both. And since the length of the screw 20 can be shortened, it becomes possible to reduce the size of the mechanical equipment.

-Other embodiments-
In addition, embodiment disclosed this time is an illustration in all the points, Comprising: It does not become a basis of limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the scope of claims. Further, the technical scope of the present invention includes all modifications within the meaning and scope equivalent to the scope of the claims.

  The present invention can be effectively used for an extruder used for resin molding.

DESCRIPTION OF SYMBOLS 1 Extruder 10 Cylinder 10a Cylindrical space 10b Inner wall surface 11 Material supply port 12 Extrusion port 20 Screw 21 Screw shaft 22 Flight 23 Groove 30 Heater 40 Hopper 50 Rotation mechanism R Resin pellet

Claims (1)

A cylinder with a heater;
A spiral groove is formed on the outer periphery, and a screw rotatably accommodated inside the cylinder;
A material supply port provided on the base end side of the cylinder;
An extrusion port provided at the tip of the cylinder,
A resin pellet that is introduced into the cylinder from the material supply port, is melted and kneaded by the heater and the screw into a molten state, and an extruder that extrudes the molten resin from the extrusion port,
The height of the groove of the screw in the vicinity of the material supply port is a height corresponding to the size of the resin pellet before melting, and the height of the groove of the screw is from the vicinity of the material supply port of the cylinder. An extruder characterized by being configured to become lower toward the outlet.

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