JP2000218677A - Screw for molding machine, extrusion molding machine and injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw for a molding machine having a simple structure and capable of efficiently plasticizing and melting a raw material resin. SOLUTION: A screw 10 for a molding machine can feed a raw material resin introduced from a hopper on an upstream end side toward a downstream end while plasticizing and melting the same and is equipped with the flight absent portion 15 provided to a compression portion C between the upstream and downstream ends. In this case, the depth of the flight absent part 15 is gradually reduced from the upstream end toward the downstream end.

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 molding machine which is applied to an extrusion molding machine, an injection molding machine or the like, and which conveys a resin material introduced into an upstream end to a downstream end while plasticizing and melting.

[0002]

2. Description of the Related Art Generally, a barrel screw (heating tube) of an extrusion molding machine or an injection molding machine is equipped with a molding machine screw for conveying various raw materials such as various pellets and resin powder while melting and kneading them. ing. From the viewpoint of each step of molding resin, such a molding machine screw is
It is roughly divided into a supply section (solid transport section) located on the upstream side, a measuring section located on the downstream side, and a compression section (plasticizing section) located in the middle between the two. Here, on the upstream side of the molding machine screw, the raw material resin such as pellets has not been melted yet, and the supply section of the molding machine screw plays a role of transporting the solid phase resin. That is, the raw resin starts melting in the compression section, and the liquid phase resin plasticized and melted in the compression section is pressurized by the measuring section.

In this case, in the compression section, first, a so-called melt film in which the raw material resin is plasticized and melted to be in a fluid state is formed in a region close to the inner wall surface of the barrel. Also, on the upstream side in the screw groove of the compression section, the plasticized and melted resin stays and forms a so-called melt pool section, and on the downstream side in the screw groove, the raw resin that is not plasticized and melted is A so-called solid bed is formed. Here, in the compression section, plasticizing and melting of the raw material resin must be effectively promoted, but the solid bed is generally pressed to the downstream side and tends to abut on the side surface of the screw flight. For this reason, the heat for melting the solid bed is mainly transferred from the melt film existing near the inner wall surface of the barrel to the solid bed, but the amount of heat transferred from the melt film to the solid bed is limited. . In this regard, a problem has been pointed out that the solid bed cannot be efficiently melted in the compression section of the screw for a molding machine.

As a technique for solving such a problem, a technique disclosed in Japanese Patent Application Laid-Open No. H8-103926 is known. The screw for a conventional molding machine described in this publication is formed by melting only the thermoplastic matrix resin of a liquid crystal resin composite in which a thermoplastic liquid crystal resin is composited into a fibrous form in a thermoplastic matrix resin. It is used at the time. This conventional screw for a molding machine has a flight non-existent portion where no screw flight is provided between the upstream end and the downstream end. When a liquid crystal resin composite is molded using this molding machine screw,
Since the contact between the solid bed and the screw flight in the flight non-existent portion can be reduced, a melt pool can be formed around the solid bed. For this reason, the amount of resin that melts from the solid bed into the melt pool can be increased.

[0005]

However, even if a flight non-existent portion is provided as in the above-described conventional screw for a molding machine, the size (volume) of the solid bed existing in the flight non-existent portion is reduced by the compression portion. The size of the solid bed existing in the screw groove of the same. For this reason, even if heat was transmitted to the solid bed from both the melt film and the melt pool part, the melting efficiency of the solid bed remained low because the thermal conductivity inside the solid bed was low. .

Accordingly, an object of the present invention is to provide a screw for a molding machine having a simple structure and capable of efficiently plasticizing and melting a raw material resin.

[0007]

According to a first aspect of the present invention, there is provided a screw for a molding machine which is capable of plasticizing and melting a raw material resin introduced at an upstream end and conveying the resin to a downstream end. Comprising a flight non-existing portion provided between the upstream end and the downstream end, wherein the depth of the flight non-existing portion gradually decreases from the upstream end to the downstream end. .

When a raw material resin such as pellets is molded by a molding machine equipped with the molding machine screw, the molding machine screw is driven to rotate in a barrel of the molding machine, and the raw material is placed on the upstream end side of the molding machine screw. Introduce resin. The introduced raw material resin is conveyed in a solid state on the upstream end side, but is gradually melted, a melt film is formed around the screw for the molding machine, and provided between the upstream end and the downstream end. A solid bed and a melt pool part are formed in the flight non-existing part. Here, in the flight non-existing portion where the screw flight is not provided, the solid bed and the screw flight do not come into contact with each other, so that the melt pool portion can be formed all around the solid bed.

Further, since the depth of the flight non-existing portion gradually decreases from the upstream end side to the downstream end side, the inner wall surface of the barrel accommodating the molding machine screw and the bottom surface of the flight non-existing portion are formed. Is gradually narrowed from the upstream side to the downstream side. For this reason, the solid bed extruded toward the downstream side comes into contact with the inner wall surface of the barrel and the bottom surface of the flight non-existent portion. At this time, the solid bed is fixed to the barrel and moves with respect to the screw for the molding machine because of the torque balance, so that the solid bed is crushed. As a result, heat is transmitted from the surrounding melt film and the melt pool to the solid bed having a small volume. It becomes possible to plasticize and melt. Further, since the screw for a molding machine has an extremely simple structure, it can be manufactured at low cost.

[0010] In this case, it is preferable to provide a projection for dividing the solid bed in the non-flight portion.
If such a configuration is adopted, the solid bed existing in the non-flight-existing portion can be pulverized by the protrusions, so that the solid bed can be plasticized and melted more efficiently.

According to a third aspect of the present invention, there is provided an extruder having a screw for a molding machine which can be conveyed to a downstream end while plasticizing and melting a raw material resin introduced to an upstream end. The molding machine screw has a flight non-existing portion provided between the upstream end and the downstream end, and the depth of the flight non-existing portion gradually decreases from the upstream end to the downstream end. It is characterized by being.

Further, the injection molding machine according to the present invention has a screw for a molding machine which can be conveyed to the downstream end side while plasticizing and melting the raw material resin introduced to the upstream end side. The molding machine screw has a flight non-existing portion provided between the upstream end and the downstream end, and the depth of the flight non-existing portion gradually decreases from the upstream end to the downstream end. It is characterized by being.

According to the extrusion molding machine and the injection molding machine, the raw material resin is efficiently plasticized and melted by the molding machine screw, so that a high quality molded product can be efficiently produced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a screw for a molding machine according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a partial sectional view showing an extruder to which a screw for a molding machine according to the present invention is applied. The extruder 1 shown in FIG. 1 has a drive unit 3 including a motor 2 and a barrel (heating cylinder) 6 supported by a support frame 4 and installed on a base unit 5. The barrel 6 is formed in a substantially cylindrical shape. A nozzle head 7 is fixed to the upstream end of the barrel 6 (the left end in FIG. 1), and a raw resin RM such as pellets or resin powder is introduced into the barrel 6 at the downstream end. Hopper 8 is attached. Also, around the barrel 6, the barrel 6
Are provided with a plurality of heaters 9 for heating the inside of the device to a predetermined temperature.

Inside the barrel 6, a screw 1 for a molding machine is provided.
0 is arranged. The molding machine screw 10 is rotationally driven by the drive unit 3 disposed on the side of the barrel 6, and plasticizes and melts the raw material resin RM introduced from the hopper 8 on the upstream end side while the nozzle head on the downstream end side. 7 can be conveyed. From the viewpoint of each step of molding the resin, the molding machine screw 10 includes a supply unit (solid transportation unit) F located on the upstream side, as shown in FIGS.
It is roughly divided into a measuring section M located on the downstream side and a compression section (plasticizing section) C located in the middle between the two.

As shown in FIGS. 2 and 3, the screw 10 for the molding machine is provided with an upstream screw flight 11a extending from the supply section F to the compression section C. The outer diameter of the upstream screw flight 11a is substantially the same in the longitudinal direction,
The depth of the upstream screw groove 12a gradually decreases from the upstream to the downstream. The screw 10 for the molding machine is provided with a downstream screw flight 11b that extends from the compression section C to the measuring section M. The outer diameter of the downstream screw flight 11b is substantially the same in the longitudinal direction, and the depth of the downstream screw groove 12b gradually decreases from the upstream to the downstream, and is substantially the same in the measuring section M. Further, a dalmage type mixing section 1 for improving kneading performance is provided at an upstream end of the screw 10 for a molding machine.
4 are provided.

Here, the molding machine screw 10 has a flight non-existent portion 15 near the center of the compression portion C located between the upstream end and the downstream end. As shown in FIGS. 2 and 3, the flight non-existent portion 15 is not provided with a screw flight. That is, in the flight non-existent portion 15, the upstream screw flight 11a and the downstream screw flight 11b which were originally continuous are disconnected. In this case, the length in the longitudinal direction of the flight non-existing portion 15 is about twice the screw diameter (the outer diameter of the screw flight).

The depth d of the flight non-existent portion 15
(The depth from the bottom surface 15a of the flight non-existent portion 15 to the outer edges of the screw flights 11a and 11b, see FIG. 5)
As shown in FIG. 2, the temperature gradually decreases from the upstream end to the downstream end. That is, in the flight non-existent portion 15, the outer diameter of the core 10a (see FIG. 5) of the molding machine screw 10 gradually increases from the upstream end toward the downstream end.

When the raw material resin RM such as pellets is formed by the extruder 1 equipped with the screw 10 for a molding machine, the screw 10 for the molding machine is rotated and driven by a drive unit 3 in a barrel 6 of the extruder 1. Raw material resin is introduced from the hopper 8 to the upstream end side of the molding machine screw 10. The introduced raw material resin RM is transported in a solid state in the upstream supply unit F, but is gradually melted from near the upstream end of the compression unit C. Thereby, the screw 10 for the molding machine is
, That is, between the inner wall surface of the barrel 6 and the screw 10 for a molding machine, a melt film is formed. Also,
A solid bed and a melt pool portion are formed in the flight nonexistent portion 15 provided in the compression section C between the upstream end and the downstream end.

Here, in the flight non-existent portion 15 where no screw flight is provided, a predetermined space is formed between the upstream screw flight 11a and the downstream screw flight 11b. There is no contact with the side screw flight 11a and the downstream screw flight 11b. This makes it possible to form a melt pool portion all around the solid bed.

Further, since the depth of the flight non-existing portion 15 gradually decreases from the upstream end to the downstream end, the inner wall surface of the barrel 6 accommodating the molding machine screw 10 and the flight non-existing portion 15 are formed. The space between the bottom surface 15a of
It gradually narrows from upstream to downstream. For this reason, the solid bed extruded toward the downstream side eventually becomes the inner wall surface of the barrel 6 and the flight non-existent portion 1.
5 is in contact with the bottom surface 15a. At this time, the solid bed is fixed to the barrel 6 and moves with respect to the molding machine screw 10 (the bottom surface 15a of the flight non-existent portion 15) because of the torque balance, so that the solid bed is crushed.

Accordingly, since heat is transmitted from the surrounding melt film and the melt pool to the solid bed having a small volume, even if the thermal conductivity inside the solid bed is low, the solid bed can be efficiently used. It becomes possible to carry out plasticizing and melting well uniformly. Further, since the screw 10 for a molding machine has an extremely simple structure, it can be manufactured at low cost. Furthermore, according to the extrusion molding machine 1 provided with the molding machine screw 10,
Since the raw material resin RM is plasticized and melted efficiently and homogeneously by the molding machine screw 10, a molded product having high quality can be efficiently produced.

The screw 10 for a molding machine described above.
Has been described as being applied to the extruder 1,
However, it is not limited to this. That is, the molding machine screw 10 can be applied to an injection molding machine. In this case, a check ring may be provided at the upstream end of the molding machine screw 10. In addition, screw 10 for molding machine
In the above, the flight non-existing portion 15 having a predetermined length is continuously provided near the approximate center of the compression portion C, but is not limited to this. That is, the length of the flight non-existing portion 15 may be set to be short and may be provided intermittently in the compression portion C.

Next, a second embodiment of a screw for a molding machine according to the present invention will be described with reference to FIGS. Note that the same elements as those of the screw 10 for a molding machine according to the first embodiment of the present invention shown in FIGS. 1 to 5 are denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIGS. 6 to 8, the flight non-existent portion 15 of the molding machine screw 10A according to the second embodiment is provided with a projection 16 for dividing the solid bed. In this molding machine screw 10A, four projections 16 formed in a rod shape are fixed to the flight non-existent portion 15. If such a configuration is adopted, the solid bed existing in the non-flight-existing portion can be pulverized by the protrusions, so that the solid bed can be plasticized and melted more efficiently. The shape of the protrusion 16 is not limited to a rod shape, and a fin-shaped protrusion may be employed. The number of the projections 16 is 4
The number of protrusions 1 is not limited to one, but may be one or more.
6 may be provided in the flight non-existence section 15.

[0027]

Since the screw for a molding machine according to the present invention is constructed as described above, the following effects can be obtained. That is, by providing a flight non-existing portion between the upstream end and the downstream end of the molding machine screw, and gradually decreasing the depth of the flight non-existing portion from the upstream end to the downstream end, a simple operation is achieved. A screw for a molding machine having a structure and capable of efficiently plasticizing and melting the raw material resin can be realized.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an extruder to which a screw for a molding machine according to the present invention is applied.

FIG. 2 is a side view showing a screw for a molding machine according to the present invention.

FIG. 3 is a development view of the screw for a molding machine shown in FIG. 2;

FIG. 4 is a sectional view taken along line IV-IV in FIG. 2;

FIG. 5 is a sectional view taken along line VV in FIG. 2;

FIG. 6 is a side view showing a second embodiment of the screw for a molding machine according to the present invention.

FIG. 7 is a development view of the screw for a molding machine shown in FIG. 6;

FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Extrusion molding machine, 6 ... Barrel, 10, 10A ... Screw for molding machines, 11a ... Screw flight on the upstream side, 11b ...
Downstream screw flight, 12a ... upstream screw groove,
12b: Downstream screw groove, 15: Flight non-existent part,
16: protrusion, C: compression section, F: supply section, M: measuring section, R
M: Raw material resin.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuji Sato 1F, Takamichi, Iwazuka-cho, Nakamura-ku, Nagoya-shi, Aichi F-term (reference) 4F206 AC01 AC04 JA02 JA03 JA04 JA05 JA07 JQ16 JQ17 JQ18 JQ23 JQ27 4F207 AC01 AC04 KA01 KL05 KL07 KL24

Claims (4)

[Claims] 1. A screw for a molding machine capable of conveying a raw resin introduced to an upstream end side to a downstream end side while plasticizing and melting the resin material, wherein no flight is provided between the upstream end and the downstream end. Wherein the depth of the non-flight portion is gradually reduced from the upstream end toward the downstream end. 2. The screw for a molding machine according to claim 1, wherein the flight non-existing portion is provided with a projection for dividing a solid bed. 3. An extruder having a screw for a molding machine that can be conveyed to a downstream end while plasticizing and melting a raw material resin introduced to an upstream end, wherein the screw for the molding machine is connected to the upstream end and the upstream end. An extruder including a flight non-existing portion provided between the extruder and the downstream end, wherein the depth of the flight non-existing portion gradually decreases from the upstream end to the downstream end. . 4. An injection molding machine having a screw for a molding machine which can be conveyed to a downstream end while plasticizing and melting a raw material resin introduced to an upstream end, wherein the screw for the molding machine comprises: An injection molding machine comprising a flight non-existing portion provided between the downstream end and a flight non-existing portion, wherein the depth of the flight non-existing portion gradually decreases from the upstream end to the downstream end. .