JP3867657B2 - Extruder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an extruder particularly suitable for use in an injection molding apparatus, and more particularly to an extruder that extrudes a molding material such as rubber supplied in a continuous tape form while being plasticized by rotation of a screw under heating.
[0002]
[Prior art]
A molding material such as rubber is supplied to an extruder, and this is forwardly fed while being plasticized (heat softened) under heating by rotation of a screw of the extruder, and extruded from the tip of a screw cylinder to an injection machine. As an injection molding device that injects into the mold from the injection machine, the molding material sent in a continuous tape form is received at the supply port of the extruder, bitten by the rotation of the screw, and then advanced forward There is something made.
[0003]
Patent Document 1 below discloses this type of injection molding apparatus.
In such an extruder, as shown in FIG. 7, a cylindrical hopper flange (supply part) 202 having an opening-shaped supply port 200 corresponding to the tape shape of the molding material 208 is used as a screw in the extruder. A tape-shaped molding material 208 is provided on the base end side of the cylinder and continuous therewith.
[0004]
As shown in FIG. 8, the hopper flange 202 is provided with an undercut-like introduction groove 204 extending in the circumferential direction following the supply port 200 on the inner peripheral surface (the introduction groove 204 is perpendicular to the axis). The molding material 208 supplied to the supply port 200 is once introduced and stocked there.
The molding material 208 stocked here is bitten by the rotation of the screw 206, and further fed forward with the rotation of the screw 206 to be plasticized.
[0005]
[Patent Document 1]
Japanese Examined Patent Publication No.7-115354 [0006]
[Problems to be solved by the invention]
Incidentally, the tape-shaped molding material 208 that is continuously fed has variations in the thickness and width of the tape, and the amount supplied to the hopper flange 202 is not necessarily constant.
Thus, even when the supply amount to the hopper flange 202 is larger than the appropriate amount, the molding material 208 put (supplied) into the supply port 200 is forcibly bitten by the rotation of the screw 206 as it is. Then it is sent forward.
[0007]
However, when the plasticized molding material 208 is pushed out from the tip of the screw cylinder, there is resistance, and an internal pressure is acting in the screw cylinder, so that an imbalance is present between the supply amount of the molding material 208 and the extrusion amount. When this occurs, the molding material 208 plasticized by the internal pressure is pushed back to the hopper flange 202 side, and a dumpling-like lump is generated at the introduction groove 204 portion.
Alternatively, the molding material 208 that is supplied to the supply port 200 and enters the hopper flange 202 is not fed forward by the internal pressure at the tip end side of the screw cylinder, and as it is rotated in the introduction groove 204 as the screw 206 rotates. It becomes.
[0008]
When a dumpling-shaped lump of the molding material 208 is generated inside the hopper flange 202, specifically, the introduction groove 204, the tape-shaped molding material 208 is pushed out by the pressure from the dumpling-shaped lump, and the hopper flange 202 is pressed there. Thus, the supply of the tape-shaped molding material 208 is cut off.
[0009]
Alternatively, the molding material 208 that has entered the hopper flange 202 is not smoothly fed forward, and the scraper action (biting action) is caused by the rotation of the screw 206 inside the hopper flange 202, specifically the rotation of the spiral flight part 210. As a result, the tape-shaped molding material 208 is cut, and as a result, the supply of the tape-shaped molding material 208 to the hopper flange 202 is interrupted.
Thus, if such a supply interruption occurs, a series of steps before and after the extrusion by the extruder are stopped.
[0010]
[Means for Solving the Problems]
The extruder of the present invention has been devised to solve such problems.
Thus, according to the first aspect of the present invention, a cylindrical supply portion having a continuous tape-shaped molding material supply port is provided on the base end side of the screw cylinder, and the molding material supplied to the supply port is screwed. An extruder that extrudes from the tip of the screw cylinder while being plasticized by rotation of the screw, and has an introduction groove extending in a circumferential direction following the supply port on the inner peripheral surface of the supply portion, and a groove bottom surface and a flight portion of the screw The molding material supplied to the supply port is guided to the introduction groove, and the introduction groove is formed in a spiral in the same direction as the spiral direction of the screw. characterized in that is formed with and helix angle of the guide grooves as a groove at an angle corresponding to the helix angle of the screw.
[0011]
Of those claims 2, Oite to claim 1, the groove width of the guide grooves is characterized in that it is gradually narrowed toward the end from the beginning.
[0012]
According to a third aspect of the present invention, in any one of the first and second aspects, the introduction groove rotates at least once in the circumferential direction .
[0013]
[Operation and effect of the invention]
As described above, according to the present invention, the introduction groove extending in the circumferential direction along the inner peripheral surface of the cylindrical supply portion following the supply port in the direction perpendicular to the conventional shaft center is the same direction as the spiral direction of the screw. It is formed as a spiral groove that forms a spiral.
[0014]
In this way, the introduction groove is a spiral groove in the same direction as the screw spiral direction, so that the molding material supplied in a tape shape continuous to the supply port can be bitten by the flight part of the screw. To be suppressed. Then, the molding material supplied to the supply port is well guided to the tip side of the screw cylinder along the spiral introduction groove, and the molding material stagnates near the supply port to generate a dumped lump there. Good avoidance.
This improves or solves the problem of the interruption of the supply of the tape-shaped molding material which has occurred conventionally.
[0015]
Here in the helix angle of the introduction groove, your clauses without the angle corresponding to the helix angle of the screw.
Further, the groove width of the introduction groove can be gradually reduced from the start end to the end (claim 2 ).
By doing in this way, the molding material that has entered the introduction groove and has advanced along the spiral can be smoothly transferred into the screw groove.
[0016]
The introduction groove can also be formed so as to rotate at least once in the circumferential direction (claim 3 ).
In such a case, the damming portion protruding to the screw side can be satisfactorily formed between the introduction groove and the introduction groove adjacent to each other in the axial direction after one rotation, and by the damming action of the damming portion, It is possible to satisfactorily inhibit the plasticized molding material on the tip side of the screw cylinder from backflowing (reverse flow) and generating a dumpling-like lump in the vicinity of the supply port .
[0017]
【Example】
Next, embodiments of the present invention will be described in detail with reference to the drawings.
In FIG. 1, 10 is a mold, 12 is an injection machine for injecting a rubber material (molding material) into the mold 10, and 14 is an extruder for extruding the plasticized rubber material into the injection machine 12.
[0018]
The injection machine 12 has an injection cylinder 16, a plunger 18, and a drive unit 20 that drives the plunger 18 downward in the figure, and pushes the rubber material in the injection cylinder 16 downward. Thus, injection is injected from the nozzle 22 at the tip into the molding cavity 24 of the mold 10.
[0019]
The extruder 14 has a screw cylinder 26, a screw 28 inside the screw cylinder 26, and a drive unit 30 that rotationally drives the screw 28, and is a tape that is continuously fed while being supported by a roller 32. The rubber material (molding material) 34 is extruded from the tip of the screw cylinder 26 into the injection cylinder 16 of the injection machine 12 while being plasticized (heat-softened) by heating by rotation of the screw 28.
[0020]
Here, the extruder 14 has a hopper flange (supply part) 36 on the proximal end side of the screw cylinder 26, and the tape-like rubber material 34 is supplied to a supply port 44 described later in the hopper flange 36. .
[0021]
FIG. 2 specifically shows the hopper flange 36 together with the screw 28.
As shown in the figure, the hopper flange 36 has a pair of flange portions 38 and 40 at axial end portions and a cylindrical portion 42 therebetween. The cylindrical portion 42 is parallel to the axial direction, that is, the front-rear direction. A supply port 44 having an elongated hole shape is provided so as to penetrate the wall of the cylindrical portion 42 inward and outward.
In the figure, reference numerals 50 and 52 denote a shaft portion and a flight portion of the screw 28, respectively.
[0022]
The hopper flange 36 also has an introduction groove 54 formed on the inner peripheral surface thereof following the supply port 44.
Here, the introduction groove 54 forms a predetermined gap between the groove bottom surface and the top surface of the flight part 52 in the screw 28, and extends in the circumferential direction along the inner peripheral surface of the hopper flange 36 while drawing a spiral. ing.
Here, the spiral direction of the introduction groove 54 is the same as the spiral direction of the screw 28, specifically, the spiral direction of the flight part 52.
[0023]
Further, the spiral angle of the introduction groove 54, that is, the inclination angle with respect to the axial center of the screw 28 is the same as that of the screw 28, that is, the flight angle of the flight part 52.
Furthermore, the introduction groove 54 has an axial pitch equal to the axial pitch of the flight part 52.
[0024]
Here, the introduction groove 54 is provided in a state in which it rotates just once in the circumferential direction.
In the drawing, 54-1 represents the start end of the introduction groove 54, and 54-2 represents the end, and the start end 54-1 and the end end 54-2 protrude inward toward the screw 28 side. Adjacent to each other in the axial direction with the part in between.
[0025]
The protruding portion is configured as a blocking portion 56 that functions to block back the rubber material 34 on the distal end side of the screw cylinder 26 from flowing back to the supply port 744 side.
The inner surface of the dam member 56 is located at substantially the same position in the radial direction as the top surface (outer surface) of the flight part 52, and there is almost no gap between them.
[0026]
FIG. 3 shows the developed shape of the introduction groove 54.
The guide grooves 54 as shown in the figure, wide groove width W ₁ in the axial direction at the starting end 54-1, is narrower groove width W ₂ in the axial direction at the end 54-2, and the starting 54- The groove width continuously changes from 1 to the end 54-2.
[0027]
As shown in FIG. 4, in this example, the introduction groove 54 has a predetermined groove depth h from the start end 54-1 to the end end 54-2. However, as shown in FIG. From the position rotated from 360 ° to the end 54-2 rotated from 360 ° to the end 54-2, the groove depth h is continuously reduced. Thus, it is possible to reach the terminal 54-2.
[0028]
As described above, in the extruder 14 of the present example, the introduction groove 54 that extends in the circumferential direction following the supply port 44 is not formed in a direction perpendicular to the axis as in the prior art, but in the spiral direction of the screw 28. Since it is formed in a form in which a gap is formed between the groove bottom surface and the top surface of the flight part 52 of the screw 28, it is continuous with the supply port 44. The rubber material 34 supplied in the form of a tape is favorably suppressed from being bitten by the flight portion 52 of the screw 28, and the rubber material 34 supplied to the supply port 44 is moved along the spiral introduction groove 54. Good guidance to the tip side of the screw cylinder 26 is possible.
As a result, it is possible to satisfactorily avoid the rubber material 34 stagnating in the vicinity of the supply port 44 and forming a dumpling-like lump there, and improve the problem of tape breakage of the rubber material 34 caused by the dumpling-like lump. Or it can be solved.
[0029]
In this example, the spiral angle of the introduction groove 54 is set to an angle corresponding to the spiral angle of the screw 28, and the groove width of the introduction groove 54 is gradually narrowed from the start end 54-1 toward the end end 54-2. The rubber molding 34 that has entered the introduction groove 54 and has advanced along the spiral groove can be smoothly transferred into the groove of the screw 28.
[0030]
The introduction groove 54 is also formed so as to rotate once in the circumferential direction, and by doing so, the damming portion 56 can be satisfactorily formed between the introduction groove and the introduction groove adjacent in the axial direction, Due to the damming action of the damming portion 56, the rubber material 34 on the front end side in the screw cylinder 26 backflows (backflow) to form a dumpling-like lump at the supply port 44, and thereby the tape-like rubber material 34. Can be suppressed well.
[0031]
5 and 6 show a reference example of the present invention.
In this example, on the inner peripheral surface of the hopper flange 36, the supply groove 44 is followed by the introduction groove 58 similar to the conventional one, that is, in the circumferential direction along the inner peripheral surface of the hopper flange 36 in a direction perpendicular to the axis of the screw 28. The extending groove 58 is provided, and at the base end corresponding to the supply port 44 of the screw 28, the flight heights h ₁ and h ₂ of the flight portion 52a are set to the flight height h ₃ of the flight portion 52 of the screw 28 main body. This is an example of lowering.
[0032]
In this example, as shown in FIG. 6A, the screw 28 has a flight height h ₃ in the main body of the screw 28 with the flight height of the flight portion 52a extending from the base end to the length L in the axial direction. It is lower than.
Here, the length L is 100 mm with respect to the axial length 60 mm of the supply port 44. That is, the flight height of the flight part 52a is lowered over a range of 100 mm.
[0033]
In this proximal end, the flight height of the flight portion 52a Yes set to be gradually increased toward in the figure from the start right, namely the screw 28 distally a smooth transition to the original flight height h ₃ It ’s like that.
In this example, the flight height h ₁ in FIG. 6A is 2.5 mm, and h ₂ is 3.5 mm. On the other hand the original flight height _{h 3} is 5mm.
[0034]
Here, the flight heights h ₁ and h ₂ of the flight part 52a are increased stepwise when viewed at every pitch, but when viewed along the spiral, the flight height continuously increases and changes. .
[0035]
Also in this example, as shown in FIGS. 6B and 6C, the cross-sectional shape of the flight part 52a is a substantially arc shape. That is, the cross-sectional shape of the top part of each flight part 52a has a smooth curved shape.
On the other hand, the cross-sectional shape of the flight part 52 of the main body part of the screw 28 has an angular rectangular shape as indicated by a two-dot chain line in (B) and (C).
[0036]
Also in this example, at the portion of the supply port 44, the flight portion 52a at the base end portion of the screw 28 can be satisfactorily suppressed from biting the tape-like rubber material 34 by the scraper action due to the rotation, and the tape breaks. Therefore, it is possible to satisfactorily prevent the supply of the rubber material 34 from being interrupted.
[0037]
In addition, in this example, since the cross-sectional shape of the flight part 52a at the base end part of the screw 28 is substantially arc-shaped, the biting of the rubber material 34 by the flight part 52a can be suppressed more favorably.
[0038]
Although the embodiments and reference examples of the present invention have been described in detail above, this is merely an example.
For example, in the above example, the present invention is applied to an extruder that plasticizes and extrudes the rubber material 34 to the injection machine 12. However, the present invention is an extruder that plasticizes a rubber material and other molding materials and simultaneously supplies them to a mold. Alternatively, it can be applied to an extruder other than such an injection molding apparatus depending on circumstances, and various modifications can be made without departing from the spirit of the present invention.
[Brief description of the drawings]
FIG. 1 is a view showing an injection molding apparatus including an extruder according to an embodiment of the present invention.
FIG. 2 is a view showing a main part of the extruder of the same example.
3 is a diagram showing in more detail the shape of the introduction groove in FIG. 2. FIG.
4 is a view showing an example of an introduction groove different from FIG.
FIG. 5 is a diagram showing a main part of a reference example .
6 is a view showing a main part of the screw in FIG. 5;
FIG. 7 is a view showing a hopper flange conventionally used in an extruder.
FIG. 8 is a view showing a cross-sectional structure of the hopper flange of FIG. 7 together with a screw.
[Explanation of symbols]
12 Injection machine 14 Extruder 26 Screw cylinder 28 Screw 34 Rubber material (molding material)
36 Hopper flange (supply section)
44 supply ports 52,52a flight portions 54, 58 guide grooves 54-1 start 54-2 termination W _{1, W 2} groove width h _{1, h} 2, _{h 3} Flight Height

Claims (3)

A cylindrical supply part having a continuous tape-shaped molding material supply port is provided on the base end side of the screw cylinder, and the molding material supplied to the supply port is plasticized by rotation of the screw while the screw cylinder An extruder for extruding from a tip,
An introduction groove extending in the circumferential direction following the supply port is provided on the inner peripheral surface of the supply unit so as to form a gap between the groove bottom surface and the top surface of the flight part of the screw, and is supplied to the supply port. together form a molding material which is to direct the said introduction groove, the introduction groove, a spiral in the same direction as the direction of the helical grooves of the screw and the helix angle of the introduction groove at an angle corresponding to the helix angle of the screw An extruder characterized by being formed. Oite to claim 1, an extruder, wherein a groove width of the guide grooves is made gradually narrower toward the end from the beginning. The extruder according to any one of claims 1 and 2 , wherein the introduction groove rotates at least once in the circumferential direction.

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