JP2002154136A - Injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding machine which can prevent air from contacting a heated and fluidized resin material,can displace the air with an inner gas, can easily control a material supply unit and can exactly supply a solid resin material to a plasticizing cylinder portion even when a high seed continuous molding is conducted. SOLUTION: An injection molding machine is equipped with a material supply unit for supplying a solid resin material SM from a hopper 1 to a plasticizing cylinder portion 10 wherein the material supply unit is a uniaxial eccentric screw pump 20 having a material passage 24, a distance between a material discharge opening 24b and a material in-take opening 24a is distant by one pitch or more of a twist of the material passage 24, a suction opening 25 in communication with a place between the material passage 24 and the outer portion of the monoaxial eccentric screw pump 20 is formed between the material in-take opening 24a and the material discharge opening 24b and the suction opening 25 is connected to vacuum means 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an injection molding machine. The injection molding machine heats, pulverizes, and fluidizes the solid resin material supplied from the material supply unit by the plasticizing cylinder, and injects the fluidized resin material into the mold from the plasticizing cylinder to mold. And manufactures molded products.
However, since the heated and fluidized resin material in the plasticizing cylinder is at a high temperature, when air comes into contact with this resin material, the material resin is oxidized by oxygen in the air, causing the molded product to change color or color. That is, so-called resin burning occurs. For this reason, vacuuming the plasticizing cylinder,
It is necessary to fill with an inert gas. The present invention relates to an injection molding machine that can prevent such fluidized resin material from coming into contact with air and causing resin burning in a molded product.

[0002]

2. Description of the Related Art In a conventional injection molding machine, as a conventional technique for preventing air from contacting a heated and fluidized resin material m, a technique described in Japanese Patent Application Laid-Open No. 6-190891 (conventional example 1) and a technique described in Japanese Patent Application Laid-Open No. HEI 6-90891. Technique described in Kaihei 8-207048 (Conventional example 2)
There is.

FIGS. 6A and 6B are schematic explanatory views of a conventional injection molding machine. FIG. 6A shows an injection molding machine of Conventional Example 1, and FIG. 6B shows an injection molding machine of Conventional Example 2. As shown in FIG. 1A, the injection molding machine of the conventional example 1 is a rotary valve type material supply machine between the hopper 1 into which the solid resin material SM is carried in and the material supply cylinder 14 of the plasticizing cylinder unit 10. A unit 120 is provided.
The rotary valve type material supply unit 120 is composed of a hollow housing 121 and a rotary valve body 122 airtightly and rotatably mounted inside the housing 121. The rotary valve body 122
A plurality of recessed pocket portions 123 are formed on the outer peripheral surface of the device. Therefore, when the rotary valve 122 is rotated, the solid resin material SM is supplied from the hopper 1 to the pocket 123, and when the rotary valve 122 further rotates, the pocket 12 is rotated.
3 falls into the material supply tube 14,
The solid resin material SM can be supplied to the plasticizing cylinder unit 10.

The hopper 1 and the material supply tube 14 are airtightly shut off by a rotary valve body 122. The material supply tube 14 has a suction port 125 connected to a vacuum pump (not shown). I have. Therefore, the inside of the plasticizing cylinder 10 can be evacuated by evacuating the suction port 125 by a vacuum pump, so that air can be prevented from coming into contact with the heated and fluidized resin material LM. .

As shown in FIG. 6 (B), the injection molding machine of the prior art 2 is provided with a shutter type material supply unit 130 between the hopper 1 and the material supply cylinder 14 of the plasticizing cylinder section 10. The shutter-type material supply unit 130 includes a supply cylinder
131 and a plurality of shutter units 141 provided in the supply cylinder 131,
142 and 143. A first shutter 141 is provided between the upper end of the supply cylinder 131 and the lower end of the hopper 1 so as to be openable and closable, and the first shutter 141 allows communication between the hopper 1 and the supply cylinder 131. , Can be airtightly closed. Further, a third shutter portion 143 is provided between the lower end of the supply tube 131 and the upper end of the material supply tube 14 of the plasticizing cylinder portion 10 so as to be openable and closable.
The third shutter 143 allows the supply tube 131 and the material supply tube 14 to communicate with each other or to be airtightly closed. A second shutter section 142 is provided between the first shutter section 141 and the third shutter section 143, and a vacuum chamber 13 is provided between the second shutter section 142 and the third shutter section 143.
3 are formed. The vacuum chamber 133 has a suction port 133p connected to a vacuum pump (not shown).

For this reason, the first shutter portion 141 and the second shutter portion 142 are opened, and the solid resin material S in the hopper 1 is opened.
M is dropped into the vacuum chamber 133, and the first shutter 141, the second shutter
After the shutter 142 is closed and the inside of the vacuum chamber 133 is evacuated, the third shutter 143 is opened to supply air to the material supply cylinder 14 when the solid resin material SM is supplied to the plasticizing cylinder 10. Can be prevented from entering.

After the vacuum chamber 133 is evacuated and an inert gas is introduced into the vacuum chamber 133 from the suction port 133p, the air interposed in the solid resin material SM is replaced with the inert gas and plasticized. It can be supplied to the cylinder unit 10.

[0008]

However, in the injection molding machine of the prior art example 1, the solid resin material SM is supplied from the pocket 123.
Is dropped into the material supply tube 14 of the plasticizing cylinder portion 10, air interposed in the solid resin material SM in the pocket portion 123 also enters the material supply tube 14 at the same time. Then, there is a problem that the air that has entered the material supply cylinder 14 may come into contact with the heated and fluidized resin material LM.
In addition, in the injection molding machine of Conventional Example 2, each of the shutter portions 141,
Since the airtightness is maintained between the hopper 1 and the vacuum chamber 133 and between the vacuum chamber 133 and the material supply cylinder 14 by the 142 and 143, the air is prevented from entering the plasticizing cylinder 10 together with the solid resin material SM. Although it is possible to replace the air with an inert gas, each of the shutter units 141, 142,
It is necessary to precisely control the movement of the 143, and there is a problem that the control becomes complicated. Further, in both the injection molding machine of the first conventional example and the injection molding machine of the second conventional example, the solid resin material SM is allowed to fall freely from the inside of the pocket portion 123 and the vacuum chamber 133 into the material supply tube 14. Thus, the solid resin material SM is supplied to the plasticizing cylinder unit 10, and the supply of the solid resin material SM can be performed only intermittently. Therefore, when high-speed continuous molding is performed,
There is a problem that the supply of the solid resin material SM is insufficient.

In view of such circumstances, the present invention can prevent air from contacting a heated and fluidized resin material,
Provide an injection molding machine that can replace air with an inert gas, easily control the material supply unit, and reliably supply the solid resin material to the plasticizing cylinder even when performing high-speed continuous molding. The purpose is to do.

[0010]

According to a first aspect of the present invention, there is provided an injection molding machine comprising: a hopper for storing a solid resin material; a plasticizing cylinder for heating and fluidizing the solid resin material; An injection molding machine comprising: a material supply unit for supplying the solid resin material to a plasticizing cylinder portion, wherein the material supply unit includes a stator having a material passage formed therein, and a rotor inserted into the material passage. A material introduction port of the single-shaft eccentric screw pump is connected to the hopper, and a material discharge port of the single-shaft eccentric screw pump is air-tightly connected to the plasticizing cylinder portion. The material outlet and the material inlet are separated by at least one pitch of the material passage twist, and between the material inlet and the material outlet, Charge and suction port communicating is formed between the passage and the outside of the uniaxial eccentric screw pump, the suction port, and wherein connected to the vacuum means.
A second aspect of the present invention is the injection molding machine according to the first aspect, wherein the twist of the material passage is separated by one pitch or more between the suction port and the material discharge port. The injection molding machine according to claim 3 is the invention according to claim 1 or 2, wherein a space between the suction port and the material introduction port is:
The twist of the material passage is separated by one pitch or more. According to a fourth aspect of the present invention, in the injection molding machine according to the first aspect, an inert gas supply is provided between the suction port and the material discharge port to communicate between the material passage and the outside of the uniaxial eccentric screw pump. The mouth is formed,
The inert gas supply port and the suction port are separated by at least one pitch of the twist of the material passage, and the inert gas supply port is connected to inert gas supply means. I do.

According to the first aspect of the present invention, when the uniaxial eccentric screw pump is driven, the solid resin material in the hopper is sucked from the material introduction port and forcedly and continuously from the material discharge port to the plasticizing cylinder. Can be supplied. Moreover, by controlling only the rotation of the rotor of the uniaxial eccentric screw pump, the amount of the solid resin material sent from the hopper to the plasticizing cylinder can be adjusted, so that the material supply unit can be easily controlled. Further, the distance between the material introduction port and the material discharge port is at least one pitch of the twist of the material passage, so that the hopper and the plasticizing cylinder portion can be airtightly shut off.
Furthermore, since the suction port is formed between the material introduction port and the material discharge port, if the space communicating with the suction port is evacuated by the vacuuming means, while removing air interposed in the solid resin material, A solid resin material can be supplied to the plasticizing cylinder. Therefore, it is possible to prevent air from entering the plasticizing cylinder together with the solid resin material, and from contacting the heated and fluidized resin material with air. Furthermore, if the rotation speed of the uniaxial eccentric screw pump is increased, the supply speed of the solid resin material to the plasticizing cylinder can be increased. Therefore, even when high-speed continuous molding is performed, the solid resin material can be reliably supplied from the hopper to the plasticizing cylinder. According to the second aspect of the invention, the suction port is separated from the material discharge port by one or more pitches of the twist of the material passage. For this reason, after the space between the hopper and the suction port is hermetically shut off by the rotor, and before the suction port communicates with the plasticizing cylinder portion, the space communicating with the suction port is evacuated by the vacuum means. Can be. Therefore, the solid resin material can be supplied to the plasticizing cylinder while removing the air present in the solid resin material. According to the third aspect of the invention, the suction port is always airtightly shut off by the hopper, the plasticizing cylinder, and the rotor. That is, since the space communicating with the suction port is a space sealed by the rotor and the stator, the air interposed in the solid resin material can be completely removed before the solid resin material is supplied to the plasticizing cylinder. . Therefore, it is possible to prevent air from entering the plasticized cylinder together with the resin material and from contacting the heated and fluidized resin material with air. Further, since the volume for vacuuming is small and the time for vacuuming can be shortened, even if the rotation speed of the single-shaft eccentric screw pump increases, air interposed in the solid resin material can be reliably removed. According to the invention of claim 4, since the inert gas supply port is formed between the suction port and the material discharge port,
If the inert gas is supplied to the space communicating with the inert gas supply port in the material passage by the inert gas supply means, the air present in the solid resin material can be reliably replaced with the inert gas. Further, in the material passage, the space communicating with the suction port and the space communicating with the inert gas supply port are always air-tightly shut off. Gas is not sucked by the evacuation means. Therefore, the amount of inert gas used for replacement can be reduced.

[0012]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic vertical sectional view of the injection molding machine of the first embodiment. As shown in the figure, the injection molding machine of the first embodiment is basically composed of a hopper 1, a plasticizing cylinder section 10, and a single-axis eccentric screw pump 20A.
The injection molding machine of the first embodiment is characterized in that the material supply unit for supplying the solid resin material SM from the hopper 1 to the plasticizing cylinder unit 10 is a single-axis eccentric screw pump 20A.

First, the hopper 1 will be described. Hopper 1
The solid resin material SM is supplied and stored therein, and the solid resin material SM is supplied to a uniaxial eccentric screw pump 20 described later from the lower end thereof.

Next, the plasticizing cylinder 10 will be described. The plasticizing cylinder unit 10 is for heating, pulverizing and fluidizing the solid resin material SM to obtain a fluidized resin material LM. The plasticizing cylinder unit 10 includes a heating cylinder 11, a screw 12, and a drive motor 13.

The heating cylinder 11 is a hollow cylindrical member. A heating device (not shown) for heating the solid resin material SM, such as a heater, is provided on a wall surface of the heating cylinder 11. A material supply cylinder 14 to which a solid resin material SM is supplied from a uniaxial eccentric screw pump 20A described later is formed at the upper rear end of the heating cylinder 11. The material supply cylinder 14 is provided with a suction port 14h, and the suction port 14h is connected to a vacuum pump (not shown). At the tip of the heating cylinder 11, a mold M is provided.

The heating cylinder 11 includes a screw 1
2 is rotatably inserted. This screw 12
Is a member having a spiral screw thread formed on the outer peripheral surface thereof. The rear end of the screw 12 is air-tightly and rotatably attached to the rear end of the heating cylinder 11. A drive motor 13 is provided at the rear end of the screw 12.
Of the main shaft is attached.

Therefore, when the drive motor 13 is driven, the screw 12 rotates. Then, the solid resin material SM between the inner surface of the heating cylinder 11 and the outer peripheral surface of the screw 12 is sent to the tip of the heating cylinder 11 while being pulverized by the threads of the screw 12. In addition, the solid resin material SM is heated by a heater or the like provided in the heating cylinder 11. Therefore, the solid resin material SM becomes the fluidized resin material LM, and the fluidized resin material LM is supplied to the mold M from the tip of the heating cylinder 11 and molded, so that a molded product can be manufactured.

A description will now be given of a single-shaft eccentric screw pump 20A which is a feature of the injection molding machine of the first embodiment. As shown in FIG. 1, the uniaxial eccentric screw pump 20A is
1. It is basically composed of a stator 22A and a rotor 23A.

The housing 21 is a hollow cylindrical member, the upper end of which is attached to the lower end of the hopper 1, and the lower end of which is air-tightly attached to the upper end of the material supply cylinder 14 of the plasticizing cylinder section 10. Have been.

A stator 22A made of an elastic material is hermetically mounted inside the housing 21. The stator 22A has a material passage 24A, which is a through hole penetrating between the upper end and the lower end. The upper end of the material passage 24A is a material introduction port 24a, which communicates with the hopper 1. The lower end of the material passage 24A is a material outlet 24b, which is air-tightly connected to the material supply cylinder 14 of the plasticizing cylinder 10.

FIG. 2 is a diagram showing a temporal change in the relative position of the stator 22A and the material passage 24A in each cross section of the single-axis eccentric screw pump 20A. As shown in FIGS. 1 and 2, the material passage 24A has an oval cross section and a material introduction port.
The cross section is twisted at least one turn between 24a and material outlet 24b. The axial length when the cross section of the material passage 24A is twisted by one turn is one pitch of the twist of the material passage 24A.

The rotor 23A is inserted into the material passage 24A. The rotor 23A is a shaft formed in a spiral shape, and the length of one pitch of the twist is the same as that of the material passage.
It is half the length of one pitch of 24A twist. This rotor 2
3A has a circular cross section whose diameter is the same length as the width of the material passage 24A.

Accordingly, the outer surface of the stator 22A and the rotor
The inner surface of 23A is in air-tight contact with each cross section, and the stator 22A and rotor
An airtight space is formed between 23A.

The upper end of the rotor 23A passes through the hopper 1 and is connected to the main shaft of a motor 27 via a flexible joint 26. The center axis of the main shaft of the motor 27 is disposed coaxially with the center axis of the stator 22A.

For this reason, when the motor 27 is driven, the rotor 23A rotates around the main axis of the motor 27, and the rotor 23A rotates.
A reciprocates in the material passage 24A in each cross section. Then, the solid resin material SM in the hopper 1 is sucked from the material introduction port 24a, and the solid resin material SM can be forcibly and continuously supplied to the plasticizing cylinder 10 from the material discharge port 24b. In addition, the uniaxial eccentric screw pump 20
If only the rotation of the rotor 23A of A is controlled, the amount of the solid resin material SM sent from the hopper 1 to the plasticizing cylinder 10 can be adjusted, so that the control is easy.

Further, the material inlet 24a of the material passage 24A is provided.
A suction port 25 communicating between the material passage 24A and the outside is formed between the material passage 24A and the material discharge port 24b. The suction port 25 is separated from the material discharge port 24b by one or more twists of the material passage 24A. Also, the suction port 25 is
For example, it is connected to evacuation means 30 such as a vacuum pump. Therefore, the space between the hopper 1 and the suction port 25 is a rotor.
After air-tightly closed by 23A and before the suction port 25 communicates with the plasticizing cylinder part 10, the evacuation means 3
With 0, the space communicating with the suction port 25 can be evacuated.

Moreover, the suction port 25 is connected to the material discharge port 24.
The space communicating with the suction port 25 is always airtight by the rotor 23A and the space communicating with the hopper 1 and the space communicating with the plasticizing cylinder 10 because the material passage 24A is separated from the material passage 24A by one or more twists. Is shut off.
That is, the space communicating with the suction port 25 is a space sealed by the rotor 23A and the stator 22A.

Therefore, if the space communicating with the suction port 25 is evacuated by the evacuation means 30, the air present in the solid resin material SM accommodated in the space can be completely removed. Therefore, the plasticizing cylinder unit 10 has SM
At the same time, air enters and it is possible to prevent air from contacting the resin material LM that has been heated and fluidized.

Further, since the space communicating with the suction port 25 has a small volume, the time for vacuuming can be shortened. Therefore, even if the rotation speed of the single-shaft eccentric screw pump 20A increases,
Air interposed in the solid resin material SM can be reliably removed.

Next, the operation and effect of the injection molding machine of the first embodiment will be described. First, the solid resin material S
M is charged, and the inside of the plasticizing cylinder 10 is evacuated from the suction port 14h of the material supply cylinder 14 by a vacuum pump.
Next, when the space passing through the suction port 25 from the suction port 25 is evacuated by the vacuuming means 30, the preparation for operating the injection molding machine is completed. In the material passage 24A,
The space communicating with the suction port 25 is constantly evacuated by the evacuation unit 30.

FIGS. 3 and 4 show a single-shaft eccentric screw pump 20.
FIG. 5 is a diagram showing a change over time in a relative position between a stator 22A and a material passage 24A in each cross section of FIG. 2 to 4, hatched portions indicate portions in which the solid resin material SM is accommodated. The angle described above each row indicates the rotation angle of the rotor 23A from the start of rotation.

As shown in FIG. 2, when the motor 27 is driven, the rotor 23A is rotated.
Since A reciprocates in the material passage 24A, the solid resin material SM in the hopper 1 is sucked from the material introduction port 24a.
The sucked solid resin material SM is sent through the material passage 24A as the rotor 23A rotates.

When the rotor 23A rotates 360 °, that is, one rotation, the space between the material introduction port 24a and the suction port 25 (in FIG. 2,
(A and C), the space formed by the stator 22A and the rotor 23A accommodates the solid resin material SM, and the space is hermetically shut off from the hopper 1 by the stator 22A and the rotor 23A.

As shown in FIG. 3, when the rotor 23A further rotates, the solid resin material SM is fed in the direction of the material discharge port 24b. Then, the space accommodating the solid resin material SM is communicated with the suction port 25, so that the air existing in the solid resin material SM is removed by the evacuation unit 40.

The suction port 25 and the space accommodating the solid resin material SM remain in communication with each other while the rotor 23A rotates from 360 ° to 720 °, that is, one rotation. The housed space is the stator 22A
The rotor 23A and the hopper 1 and the plasticizing cylinder 10 are airtightly shut off by the rotor 23A. Therefore, the air present in the solid resin material SM can be completely removed by the vacuuming means 40.

As shown in FIG. 4, when the rotor 23A further rotates, the space containing the solid resin material SM communicates with the material discharge port 24b, and the solid resin material SM flows from the material discharge port 24b to the material supply cylinder 14. Supplied. This solid resin material S
Since air is completely removed from M, air does not enter the material supply cylinder 14 together with the solid resin material SM, and the degree of vacuum in the plasticizing cylinder unit 10 does not decrease.

Therefore, according to the injection molding machine of this embodiment, when the uniaxial eccentric screw pump 20A is driven, the solid resin material SM in the hopper 1 is sucked from the material inlet 24a and plasticized from the material outlet 24b. Can be forcibly and continuously supplied to the forming cylinder unit 10. Moreover, before the solid resin material SM is supplied to the plasticizing cylinder 10, the air interposed in the solid resin material SM can be completely removed, so that air enters the plasticizing cylinder 10 together with the solid resin material SM and is heated. It is possible to prevent air from contacting the fluidized resin material LM.

When high-speed continuous molding is performed, the supply speed of the solid resin material SM to the plasticizing cylinder 10 can be increased by increasing the rotation speed of the uniaxial eccentric screw pump 20A. Even if it is performed, the solid resin material SM can be reliably supplied from the hopper 1 to the plasticizing cylinder unit 10.

Next, an injection molding machine according to a second embodiment will be described. FIG. 5 is a schematic longitudinal sectional view of the injection molding machine of the second embodiment. As shown in the figure, the injection molding machine of the second embodiment is basically composed of a hopper 1, a plasticizing cylinder section 10, and a uniaxial eccentric screw pump 20A. In the injection molding machine of the second embodiment, similarly to the injection molding machine of the first embodiment, a material supply unit for supplying the solid resin material SM from the hopper 1 to the plasticizing cylinder unit 10 includes a uniaxial eccentric screw pump 20B. However, the single shaft eccentric screw pump 20B
By providing an inert gas supply port 40 in addition to the suction port 25, the air present in the solid resin material SM can be replaced with an inert gas.

Therefore, a description will be given of a uniaxial eccentric screw pump 20B which is a feature of the injection molding machine of the second embodiment. FIG.
As shown in the figure, the single-axis eccentric screw pump 20B
B is twisted at least two turns between the material inlet 24a and the material outlet 24b. This single shaft eccentric screw pump
An inert gas supply port 40 communicating between the material passage 24B and the outside is formed between the suction port 25 of 20B and the material discharge port 24b. This inert gas supply port 40 is
The material passage 24B is separated from the suction port 25 by a twist of one pitch or more. For this reason, the space communicating with the inert gas supply port 40 is different from the space communicating with the suction port 25 and the rotor 23B.
Is always airtight shut off. The distance between the inert gas supply port 40 and the suction port 25 is determined by the material passage 24b.
May be slightly shorter than the length of one twist.

The inert gas supply port 40 is provided with an inert gas supply means 4 for supplying an inert gas such as nitrogen or argon.
5 is connected.

Therefore, according to the injection molding machine of the second embodiment, the inert gas supply port 40 is connected to the suction port 25 and the material passage 24b.
And the inert gas supply means 45
When the inert gas is supplied to the space communicating with the inert gas supply port 40 in the material passage 24B by the
Can be reliably replaced with the inert gas.

In the material passage 24B, the suction port 25
The space communicating with the inert gas supply port 40 and the space communicating with the inert gas supply port 40 are always air-tightly shut off. Will not be sucked.

If the inert gas supply port 40 is provided at least one pitch of the twist of the material passage 24B from the material discharge port 24b as well as the suction port 25, the inert gas supply port 40 communicates with the inert gas supply port 40. Since the space is a space closed by the rotor 23B and the stator 22B, the following effects can be obtained.

First, the solid resin material SM is supplied to the material outlet 24b.
Since the pressure of the inert gas flowing into the plasticizing cylinder 10 together with the solid resin material SM when supplied from the plasticizing cylinder 10 to the plasticizing cylinder 10 can be made equal to the pressure in the plasticizing cylinder 10, It is possible to reduce the change in the atmospheric pressure in the forming cylinder unit 10. In addition, the inert gas supply port 40
Does not flow to the plasticizing cylinder section 10. Therefore, the amount of inert gas used for replacement can be reduced. Further, the volume of the space communicating with the inert gas supply port 40 is reduced, and the work of replacing the air with the inert gas is accelerated. Therefore, even if the rotation speed of the single-shaft eccentric screw pump 20B increases, the air can be reliably replaced with the inert gas.

[0046]

According to the first aspect of the present invention, the solid resin material in the hopper can be forcibly and continuously supplied to the plasticizing cylinder portion, and the control of the material supply unit is easy. In addition, since the solid resin material can be supplied to the plasticizing cylinder part while removing air interposed in the solid resin material by the evacuation means, air enters the plasticizing cylinder part together with the solid resin material, and the plasticizing cylinder part is heated. It is possible to prevent air from contacting the fluidized resin material. Furthermore, if the rotation speed of the uniaxial eccentric screw pump is increased, the supply speed of the solid resin material to the plasticizing cylinder can be increased. Therefore, even when high-speed continuous molding is performed, the solid resin material can be reliably supplied from the hopper to the plasticizing cylinder. According to the invention of claim 2,
After the hopper and the suction port are hermetically shut off by the rotor and before the suction port communicates with the plasticizing cylinder portion, the space communicating with the suction port can be evacuated by the vacuuming means. Therefore, the solid resin material can be supplied to the plasticizing cylinder while removing the air present in the solid resin material. According to the invention of claim 3,
Air enters the plasticizing cylinder together with the resin material, and it is possible to prevent air from contacting the heated and fluidized resin material. In addition, since the volume for vacuuming is small, even if the rotation speed of the uniaxial eccentric screw pump is increased, air interposed in the solid resin material can be reliably removed. According to the fourth aspect of the invention, the air can be reliably replaced with the inert gas, and the amount of the inert gas used for the replacement can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of an injection molding machine according to a first embodiment.

FIG. 2 is a diagram showing a temporal change in a relative position between a stator 22A and a material passage 24A in each cross section of the single-axis eccentric screw pump 20A.

FIG. 3 is a diagram showing a temporal change in a relative position between a stator 22A and a material passage 24A in each cross section of the single-axis eccentric screw pump 20A.

FIG. 4 is a diagram showing a temporal change in a relative position of a stator 22A and a material passage 24A in each cross section of the single-axis eccentric screw pump 20A.

FIG. 5 is a schematic longitudinal sectional view of an injection molding machine according to a second embodiment.

FIG. 6 is a schematic explanatory view of a conventional injection molding machine, wherein (A)
2 shows the injection molding machine of Conventional Example 1, and (B) shows the injection molding machine of Conventional Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hopper 10 Plasticizing cylinder part 20 Uniaxial eccentric screw pump 22 Stator 23 Rotor 24 Material passage 24a Material introduction port 24b Material discharge port 25 Suction port 30 Vacuum evacuation means 40 Inert gas supply port 45 Inert gas supply means SM Solid resin material

Claims (4)

[Claims] 1. A hopper in which a solid resin material is stored, a plasticizing cylinder for heating and fluidizing the solid resin material, and a plasticizer for supplying the solid resin material from the hopper to the plasticizing cylinder. An injection molding machine comprising a material supply unit, wherein the material supply unit is a single-shaft eccentric screw pump including a stator having a material passage formed therein and a rotor inserted into the material passage. The material introduction port is communicated with the hopper, the material discharge port of the uniaxial eccentric screw pump is air-tightly communicated with the plasticizing cylinder portion, and a gap between the material discharge port and the material introduction port is provided. The material passage is separated by at least one pitch of twist, and between the material introduction port and the material discharge port, the material passage and the outside of the uniaxial eccentric screw pump. And suction port communicating is formed between an injection molding machine in which the suction port, characterized in that connected to the vacuum means. 2. The injection molding machine according to claim 1, wherein a twist of said material passage is separated by at least one pitch between said suction port and said material discharge port. 3. The injection molding machine according to claim 1, wherein a twist of the material passage is separated by at least one pitch between the suction port and the material introduction port. 4. An inert gas supply port is provided between the suction port and the material discharge port, the inert gas supply port communicating between the material passage and the outside of the uniaxial eccentric screw pump. 2. The apparatus according to claim 1, wherein a gap between the port and the suction port is at least one pitch of the twist of the material passage, and the inert gas supply port is connected to inert gas supply means. 4. The injection molding machine according to 2 or 3.