JP2012228784A - Biaxial different direction rotary extruder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxial different direction rotary extruder that secures the strength of the screw tip without causing restriction for design of a die head, and can reduce the pressure fluctuation in the cylinder by preventing the retention of the resin.SOLUTION: An adapter 5 in which a through-hole 5a that communicates an opening of a cylinder 2 and an opening of a die head 20 is provided is arranged between the cylinder 2 and the die head 20. Protrusion shafts 21 and 22 that project from the cylinder 2 are provided to the ends of the screws 3 and 4. Bearings 23 and 24 that support the protrusion shafts 21 and 22 are provided at the adapter 5.

Description

  The present invention relates to a biaxial different-direction rotary extruder used for extrusion molding of a thermoplastic resin or the like.

  2. Description of the Related Art A biaxial different-direction rotary extruder is one in which a biaxial screw is rotated in a different direction within a hollow portion of a cylinder, and is often used for manufacturing an extruded shape made of a synthetic resin.

  As shown in FIG. 7, Patent Document 1 discloses a two-shaft rotating extruder including a cylinder (2) having a built-in heater and a two-shaft disposed in a hollow portion (2a) of the cylinder (2). Screw (3), motor (M) for rotating twin screw (3), hopper (H) for supplying thermoplastic resin (P) to the base end side of cylinder (2), cylinder (2) The die head (6) attached to the tip of the screw, the funnel-shaped cap (7) attached to the tip of each screw (3), and the die head (6) provided on the axis of the screw (3) Each of the caps with shafts (7) has a cylindrical part (13) whose base end is screwed to the screw (3), and a cylindrical part. A taper portion (14) that is continuous with the tip of (13) and a shaft portion (15) extending in the axial direction from the tip of the taper portion (14) have been proposed.

  The die head (6) has a resin extrusion passage (11) with a circular cross section (a circle centered at the center between the shaft centers of each screw) that opens to the opposite cylinder side, and a cylinder side opening (12a) that has a cylinder (2 ) Hollow portion (2a) having the same cross-sectional shape (glass shape) as the cross-sectional area is gradually reduced and the resin guide passage (12) leading to the resin extrusion passage (11) and the bearing portion (8 ) Is inserted into the bottomed hole (6a). The bearing portion (8) is disposed so as to face the resin extrusion passage (11) in the direction of the drawing sheet so as not to interfere with the resin extrusion passage (11).

JP 2010-247383 A

  According to the biaxial counter-rotating extruder of Patent Document 1 shown in FIG. 7 above, the shaft cap (7) which is the tip of the screw (3) is provided by the bearing portion (8) provided on the die head (6). By being supported, there is an advantage that the vibration of the screw (3) can be prevented.

  However, since the bearing portion (8) is provided in the die head (6), the diameter of the resin extrusion passage (11) <the distance between the axes of the biaxial screw (3) −the radius of the bearing portion (8) × 2. It is necessary to secure the relationship. Therefore, there is a problem that the degree of freedom in designing the die head (6) (especially the size of the diameter of the resin extrusion passage (11)) is restricted, and the diameter of the bearing (8) is also restricted. Since the diameter of the shaft portion (15) that forms the tip portion of the screw (3) cannot be increased, it is difficult to increase the strength of the screw tip portion. Further, since the hole (6a) into which the bearing portion (8) is inserted needs to have a bottom, the resin tends to stay here, and depending on the resin, this stay may have an adverse effect. There is also a problem that maintenance is troublesome.

  The object of the present invention is to reduce the pressure fluctuation in the cylinder without restricting the die head design, ensuring the strength of the screw tip, and preventing the resin from staying in view of the current state of the prior art described above. Is to provide a twin-screw counter-rotating extruder capable of reducing the size.

  A biaxial counter-rotating extruder according to the present invention includes a cylinder, a biaxial screw arranged in a hollow portion of the cylinder and rotated in a different direction, and a die head arranged on the tip side of the cylinder. In the counter-rotating extruder, an adapter provided with a through-hole that communicates the opening of the cylinder and the opening of the die head is disposed between the cylinder and the die head, and a protruding shaft that protrudes from the cylinder is provided at the screw tip. The adapter is provided with a bearing portion that supports the protruding shaft portion.

  The adapter interposed between the cylinder and the die head is provided with a through hole that communicates the opening of the cylinder and the opening of the die head, thereby ensuring a resin passage that leads from the opening of the cylinder to the opening of the die head. The projecting shaft portion is fixed to the screw so that the shaft center thereof coincides with the shaft center of the corresponding screw. And the bearing part which fits by this protrusion shaft part and supports this rotatably is provided in the through-hole of an adapter. As the die head, a conventional one having no bearing portion is used. The clearance gap between the protruding shaft portion and the bearing portion is set to about 5 to 100 μm.

  In this way, the protruding shaft portion provided at the tip of the screw is rotationally supported by the bearing portion provided on the adapter, so that the vibration of the screw in the direction orthogonal to the axial direction is suppressed, and thereby the pressure caused by the resin in the cylinder The fluctuation becomes smaller. Since the pressure fluctuation adversely affects the generation of scratches in the cylinder and the quality of the extruded product, the fluctuation of the pressure can be suppressed, thereby extending the equipment life and improving the quality of the extruded product.

  When the bearing portion is provided in the die head, the degree of freedom in designing the die head is restricted, and there is a problem that the diameter of the bearing portion and the diameter of the screw tip supported by the bearing portion must be reduced. There is also a problem that the resin tends to stay in the bearing portion.

  On the other hand, according to the biaxial counter-rotating extruder of the present invention, by providing the bearing portion on the adapter, which is a separate member from the die head, the diameter of the bearing portion is about the same as the diameter of the shaft portion of the screw. Since the die head can be made large and the die head has no bearing, the degree of freedom in designing the die head is not restricted. Further, since both ends of the bearing portion are opened, there is an advantage that the resin hardly stays.

  The shape of the biaxial screw may be a parallel type in which the two axes are parallel, or may be a conical type in which the distance between the axes of the two axes is gradually reduced.

  The bearing portion may be formed integrally with the adapter, or may be a separate member from the adapter. In any case, the bearing portion has a cylindrical portion into which the protruding shaft portion is fitted, and a plurality of bridge portions passed between the outer peripheral surface of the cylindrical portion and the peripheral surface of the through hole. It is preferable.

  The adapter, the bearing portion that is a separate member from the adapter, and the protruding shaft portion are formed of an appropriate metal (stainless steel, steel) or the like. More preferably, a solid lubricant layer is formed on the inner periphery of the cylindrical portion of the bearing portion. The solid lubricant layer may be coated, but preferably, the cylindrical portion has a double-cylinder structure, and the cylindrical portion of the bearing portion includes an outer cylinder integrally provided with a bridge portion, and an inner cylinder. The inner cylinder is detachably fitted, and the inner cylinder is formed of a self-lubricating material such as a solid lubricant-dispersed sintered material. If it does in this way, an other member can be used as it is by exchanging only the inner cylinder worn by use. It is also possible to integrally form the main body portion, the outer tube and the bridge portion of the adapter, and to fit the inner tube of another member formed of a self-lubricating material into this.

  The number of bridge portions is, for example, two, and is arranged linearly via a cylindrical portion. The number of bridge portions may be three or more and may be arranged at a required interval in the circumferential direction.

  In the case of a biaxial counter-rotating extruder, in the kneading part near the tip of the biaxial screw, in the lower part of the part where the screws mesh with each other, the molten thermoplastic resin gathers from both sides, and the pressure in this part increases, Since the thermoplastic resin is separated at the upper part of the cylinder and the pressure at this part becomes smaller, the fluctuation of the pressure causes the vibration of the screw, and the upper inner surface of the cylinder is easily damaged. Therefore, by adjusting the direction of the bridge portion to a direction in which the vibration of the screw is likely to occur, it can be advantageous in preventing the occurrence of scratches on the upper inner surface of the cylinder. For example, when there are two bridge portions and these are arranged in a straight line through the cylindrical portion, the angle formed by the bridge portion of one bearing portion and the bridge portion of the other bearing portion is 10:10. It is set to be in the direction.

  It is preferable that a spiral groove is formed on the outer peripheral surface of the protruding shaft portion.

  A gap is provided between the projecting shaft portion and the cylindrical portion of the bearing portion so that they can be rotated relative to each other. By adjusting this gap, the resin can be prevented from entering the gap. . However, it is difficult to completely eliminate the intrusion. Therefore, by providing a helical groove on the outer peripheral surface of the protruding shaft portion, when the protruding shaft portion rotates in the bearing portion (cylindrical portion), the resin enters the helical groove of the protruding shaft portion one after another. In addition to the structure in which both ends of the bearing part are opened, a feeding function by a spiral groove is added, and it is further prevented that resin stays between the protruding shaft part and the bearing part. Is done. The direction of the spiral groove is the same as the direction of the spiral blade provided in the screw, whereby the resin in the bearing portion is sent in the same direction as that sent out by the screw. The direction of the spiral groove may be the direction opposite to the spiral blade of the screw. In this case, the resin in the bearing portion is sent in the direction opposite to the direction sent out by the screw, and then by the screw. Even in this case, the resin is prevented from staying between the protruding shaft portion and the bearing portion.

  Also, the bearing portion is a member different from the adapter provided with the through hole, and the radially outer end of the bridge portion fixed to the cylindrical portion is provided on the inner peripheral surface of the adapter through hole. It is preferable that the groove is detachably fitted.

  In this way, the bearing portion can be easily processed, and a material having excellent lubricity can be used as the bearing portion.If the bearing portion is worn, the adapter can be used as it is. Only the bearing can be replaced. In a conical type biaxial counter-rotating extruder, it is difficult to form a bearing part integrally with an adapter, but it can be easily applied to a conical type by processing the bearing part as a separate member. be able to.

  The protruding shaft is provided with a female screw on the inner periphery of the base, and is mounted on the inner periphery of the screw tip so that it is screwed onto a male screw member that is screwed onto the screw, so that it can be detachably attached to the screw. It is preferable that In the existing biaxial counter-rotating extruder, each screw has a screw cap fitted into a screw hole formed at the tip of the spline shaft, with a plurality of screw segments fitted into the shaft provided with the spline. In this case, instead of the screw cap, a protruding shaft portion (with a spiral groove) having the same threaded portion as the screw cap and the tip portion protruding in the axial direction may be used. By using it, it is possible to obtain a biaxial counter-rotating extruder according to the present invention without changing an existing screw. As a matter of course, various conventional ones can be used for the configuration of the biaxial different-direction rotary extruder other than the protruding shaft portion and the adapter. Further, since the vibration of the screw can be suppressed and the cylinder can be prevented from being damaged, the material and surface treatment of the screw and cylinder can be changed from the conventional ones.

  The biaxial counter-rotating extruder according to the present invention can be obtained by using an existing die head, replacing the existing screw cap with a protruding shaft portion, and adding an adapter, and changing other equipment. Therefore, it is possible to prevent the vibration of the screw during extrusion molding.

  The thermoplastic resin targeted by the biaxial counter-rotating extruder of the present invention is not particularly limited. For example, a resin having a high melt viscosity, which is difficult to be melt-molded such as melt extrusion, a resin that is easily decomposed by heat, a low Examples include difficult-to-mold resins containing additives having boiling points or additives that are easily thermally decomposed. Resins for engineering plastics such as ultra-high molecular weight polyethylene, ultra-high polymerization degree polyvinyl chloride, polytetrafluoroethylene, polyimide and the like can be cited as examples of resins that are difficult to be melt-molded such as melt extrusion due to their high melt viscosity. Examples of the resin that is easily pyrolyzed include biodegradable resins such as polylactic acid and polyhydroxybutyrate, high chlorinated polyvinyl chloride, and polyacrylonitrile. You may mix | blend an appropriate foaming agent with these resin as needed.

  According to the biaxial counter-rotating extruder of the present invention, the protruding shaft portion provided at the screw tip is rotationally supported by the bearing portion provided in the adapter, so that the vibration of the screw in the direction orthogonal to the axial direction is suppressed. Therefore, the pressure fluctuation due to the resin in the cylinder is reduced. Since the die head is not provided with a bearing portion, there is no restriction on the degree of freedom in designing the die head and the diameter of the bearing portion, and the strength of the screw tip portion can be easily secured. Further, since both ends of the bearing portion are opened, an advantage that the resin is less likely to stay can be obtained, and excellent maintainability can be obtained.

FIG. 1 is a longitudinal sectional view showing an embodiment of a biaxial counter-rotating extruder according to the present invention. FIG. 2 is a front view of the adapter of the biaxial counter-rotating extruder according to the present invention. 3 is a cross-sectional view taken along line III-IIII in FIG. FIG. 4 is a perspective view of a protruding shaft portion of the biaxial different-direction rotary extruder according to the present invention. FIG. 5 is a perspective view of an adapter of a biaxial counter-rotating extruder according to the present invention. FIG. 6 is an exploded perspective view showing a main part of the two-axis different direction rotary extruder according to the present invention. FIG. 7 is a longitudinal sectional view showing a conventional biaxial different-direction rotary extruder.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 6 show a two-shaft counter-rotating extruder according to the present invention.

  The biaxial counter-rotating extruder (1) has a cylinder (2) with a built-in heater, a pair of screws (3) (4) arranged in the hollow part (2a) of the cylinder (2), and a cylinder. A die head (20) attached to the tip of (2) via an adapter (5) is provided.

  Each screw (3) (4) has a shaft portion (3a) (4a) and a spiral blade (3b) (4b) formed integrally with the shaft portion (3a) (4a), respectively. Yes. A pair of screws (3) and (4) rotate in opposite directions, and a pair of screws (3) and (4) mesh with each other on the lower side, and a pair of screws (3) and (4) on the upper side. It is supposed to rotate away (rotate in a different direction).

  The hollow part (2a) of the cylinder (2) has a slightly larger cross-sectional shape than the diameter of each screw (3) (4) so that a pair of screws (3) (4) can be inserted rotatably. Two circles (circles centered on the axes of the screws (3) and (4)) are overlapped to form a glass shape.

  On the opposite cylinder side of the die head (20), a die manufactured according to the extrusion shape of a pipe, a sheet, a profile, or the like is detachably attached via an attachment fitting. The die head (20) is provided with a resin guide passage (20a) that opens to the cylinder side (adapter side) and a resin extrusion passage (20b) that opens to the opposite cylinder side. The resin extrusion passage (20b) has a circular cross-sectional shape centered at the center between the shaft centers of the screws (3) and (4). The resin guide passage (20a) has the same shape as the cross-sectional shape (glass shape) of the hollow portion (2a) of the cylinder (2), and the cross-sectional area gradually decreases, leading to the resin extrusion passage (20b).

  The adapter (5) is provided with a through hole (5a) for communicating the hollow portion (2a) of the cylinder (2) with the resin guide passage (20a) of the die head (20). The adapter (5) is further provided with a bolt insertion hole (5b) for inserting a bolt and a positioning hole (5c) to be fitted to a positioning pin (not shown) provided on the end surface of the cylinder (2). It is attached to the cylinder (2) with bolts for attaching the die head (20).

  The tip of each screw (3) (4) protrudes from the cylinder (2), and the tip of the protruding shaft (21), (22) faces the inlet of the resin guide passage (20a) of the die head (20). ) Is provided. Each protruding shaft portion (21) (22) has a conical tip, and spiral grooves (21a) (22a) are formed on the outer peripheral surface thereof. The protruding shaft portions (21) and (22) are separate members from the screws (3) and (4), and are provided on the inner peripheral surface of the base end portion, so that the screw portions are the tip portions of the screws (3) and (4). Are attached to the screws (3) and (4) in a detachable manner.

  The adapter (5) is arranged between the cylinder (2) and the die head (20) to support the protruding shafts (21) (22) of each screw (3) (4). 5) is provided with bearing portions (23) and (24) for supporting the protruding shaft portions (21) and (22) of the screws (3) and (4).

  A pair of bearings (23) and (24) is provided corresponding to the protruding shafts (21) and (22) of each screw (3) and (4), and is a separate member from the adapter (5). It is detachably attached to the adapter (5).

  Each bearing portion (23) (24) includes a cylindrical portion (25) (27) into which the protruding shaft portion (21) (22) is fitted, and the outer peripheral surface of the cylindrical portion (25) (27) and the through hole (5a ) And a pair of bridge portions (26) and (28) passed between the peripheral surfaces. Each cylindrical part (25) (27) is attached to and detached from the outer cylinder (25a) (27a) and the inner peripheral surface of the outer cylinder (25a) (27a) in which the bridge parts (26) (28) are integrally provided. The inner cylinder (25b) (27b) can be fitted.

  The inner cylinders (25b) and (27b) are formed of a solid lubricant-dispersed sintered material. Solid lubricant-dispersed sintered materials are obtained by uniformly dispersing solid lubricants (graphite, molybdenum disulfide, etc.) in the structure of sintered alloys (bronze-based and iron-based metal base materials) by powder metallurgy. It is self-lubricating (sliding) and has excellent heat resistance. In this way, by replacing only the inner cylinder (25b) (27b) worn by use, the other member (the outer cylinder (25a) (25a) ( 27a)) can be used as is. The material of the inner cylinders (25b) and (27b) is not limited to the solid lubricant-dispersed sintered material, and various materials for bearings can be used as appropriate.

  The shafts of the projecting shafts (21) and (22) of the screws (3) and (4) and the shafts of the cylindrical parts (25) and (27) of the bearings (23) and (24) are connected to the screws (3). The projecting shaft portions (21) and (22) are aligned with the shaft center of (4), and the inner cylinder (25b) of the cylindrical portion (25) (27) of the corresponding bearing portion (23) (24). (27b) is fitted in a rotatable manner.

  The pair of bridge portions (26) and (28) are arranged in a straight line (positions spaced by 180 °) via the cylindrical portions (25) and (27). The radially outer end (26a) (28a) of each bridge part (26) (28) can be attached to and detached from the groove (29) (30) provided on the peripheral surface of the through hole (5a) of the adapter (5). It is inserted in. The grooves (29) and (30) have a substantially T-shaped cross section in which the large-diameter portion is wider than the inner-diameter portion, and corresponding to this, the bridge portions (26) and (28) The radially outer ends (26a) and (28a) are also substantially T-shaped in cross section.

  The direction of the bridge parts (26) and (28) is not parallel to the line (biaxial center line) perpendicular to the line connecting the axes of the screws (3) and (4), but is inclined. Is set to As shown in FIG. 2, the upper ends of the upper bridge portions (26) and (28) are separated from the biaxial center line and the lower ends of the lower bridge portions (26) and (28) are biaxial center lines as shown in FIG. (The angle between the bridge portion (26) of one bearing portion (23) and the bridge portion (28) of the other bearing portion (24) is set to 10:10) ing.

  In the above, the die head (20) is the same as a conventional bearingless die head, and the projecting shaft portions (21) and (22) with spiral grooves (21a and 22a) are rotated in two different directions. It replaces the screw cap used to secure the screw segment in the extruder. Therefore, the biaxial counter-rotating extruder (1) according to the present invention is obtained without changing the extruder main body such as the cylinder (2) and the biaxial screw (3).

  In order to confirm the effect of the biaxial counter-rotating extruder (1) according to the present invention, the existing equipment (without screw cap and adapter only for screw function) and that of the present invention (screw cap with spiral groove (21a) (22a The cylinder (2) internal pressure comparison experiment was carried out with respect to the projecting shaft portions (21) and (22) with a) and adapters with bearings (23) and (24) added.

  According to this, the pressure fluctuation width of each part in the cylinder (2) reaches about 4 MPa depending on the place in the conventional one, but in the case of the present invention, it is within about 1 MPa in any place. Therefore, according to the biaxial counter-rotating extruder (1) of the present invention, it is possible to suppress pressure fluctuations, and scratches and wear of the cylinder (2) can be suppressed. ) Can be improved, stable extrusion can be performed, and the product quality of the extruded product is also improved.

  Here, the outer diameter of the bearing portions (23) and (24) provided on the adapter (5) should be the same as or slightly larger than the outer diameter of the shaft portions (3a) and (4a) of the screws (3) and (4). Therefore, the outer diameter of the protruding shaft portions (21) and (22) can be increased to the same extent as the outer diameter of the shaft portions (3a) and (4a) of the screws (3) and (4). Compared to the one using the die head (6) with bearing (8) shown in Fig. 7, it is possible to increase the strength of the screw tip and to reduce pressure fluctuation in the cylinder (2). It will be something. Further, since the die head (20) is a bearingless die head, the degree of freedom in designing the die head (20) is not restricted. Also, both ends of the bearing portion (23) (24) are open, and the projecting shaft portion (21) (22) with the spiral groove (21a) (22a) rotates inside this, so the resin is retained. There is also an advantage that it is difficult to do.

(1) Two-axis different direction rotary extruder
(2) Cylinder
(2a) Hollow part
(3) (4) Twin screw
(5) Adapter
(5a) Through hole
(20) Die head
(21) (22) Protruding shaft
(21a) (22a) Spiral groove
(23) (24) Bearing
(25) (27) Cylindrical part
(26) (28) Bridge part

Claims (4)

  In a biaxial counter-rotating extruder comprising a cylinder, a biaxial screw arranged in a hollow portion of the cylinder and rotated in a different direction, and a die head arranged on the tip side of the cylinder, An adapter provided with a through-hole that communicates the opening of the cylinder and the opening of the die head is disposed between them, and a protruding shaft that protrudes from the cylinder is provided at the tip of the screw. A biaxial different-direction rotary extruder, characterized in that a supporting bearing portion is provided.   The bearing portion includes a cylindrical portion into which the protruding shaft portion is fitted, and a plurality of bridge portions passed between the outer peripheral surface of the cylindrical portion and the peripheral surface of the through hole. 1. A biaxial different-direction rotary extruder according to 1.   The biaxial different-direction rotary extruder according to claim 1 or 2, wherein a spiral groove is formed on the outer peripheral surface of the protruding shaft portion.   The bearing portion is a member different from the adapter provided with the through hole, and the radially outer end portion of the bridge portion fixed to the cylindrical portion is formed in a groove provided on the inner peripheral surface of the adapter through hole. The biaxial counter-rotating extruder according to any one of claims 1 to 3, wherein the extruder is detachably fitted.

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