JP3524857B2 - Method and apparatus for stabilizing measurement of metal injection molding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for stabilizing the weighing of an in-line screw type metal injection molding machine for magnesium alloy, aluminum alloy, zinc alloy and the like.

[0002]

2. Description of the Related Art Conventionally, as an in-line screw type metal injection molding machine, one having a structure shown in FIG. 2 has been generally adopted. As shown in the figure, the metal injection molding machine rotates a cylinder barrel 1, a screw 2 that rotates and reciprocates in the cylinder barrel 1 in the axial direction, a screw drive device 7 that advances the screw 2 at high speed, and a screw 2. It is composed of a motor 8 and the like.

In the above molding machine, the screw 2 is rotated by a motor 8 and a solid molding material, for example, a low melting point alloy material chip (hereinafter referred to as material chip) 15 is used.
The hopper 11 feeds the cylinder barrel 1 from a feed port 1a through a constant-volume feed screw type feeder 10. The material chip 15 reaches the metering section from the supply section of the screw 2 through the compression section by the rotation of the screw 2, and the heat applied from the heater 4 provided on the outer circumference of the cylinder barrel 1 and the shearing force by the screw rotation during that time. It is kneaded and melted to a completely molten state or a semi-molten state. And
The screw 2 is retracted by the reaction force of the transportation propulsive force or the screw drive device 7 and the like, and a storage chamber 6 of a molding material of a molten state or a semi-molten material (hereinafter referred to as a molten material) is formed at the tip of the cylinder barrel 1. , A predetermined amount of molten material is weighed therein. Next, the screw 2 is advanced at high speed in the axial direction by the screw driving device 7, so that the backflow prevention ring 5 attached to the tip end of the screw 2 is closed,
The measured molten material is injected into the cavity from the nozzle 3 provided at the tip of the cylinder barrel 1 through the runner and gate of the die 9 that is clamped, and the molded product 1 is obtained.
6 is obtained.

[0004]

As described above, the screw used in the metal injection molding machine is divided into three zones from the hopper side to the tip, that is, the supply section, the compression section, and the metering section. In the weighing process, the supply unit preheats the material chips fed from the hopper while transferring them forward, and sends the material chips to the next compression unit. The compression unit melts the molding material by the shearing action and the heat quantity from the heater attached to the outer circumference of the cylinder barrel, and sends the molding material to the next metering unit. The metering unit homogenizes the molten material in the molten state or the semi-molten state and sends it to the tip side of the cylinder barrel.

Since the screw has no heating means, the temperature is lower than the temperature of the cylinder barrel which is always heated by the heater. Further, since the screw supply unit is adjacent to the cylinder flange and the screw driving device having no heating means, the temperature becomes lower than the temperature of the cylinder barrel.

At the start of molding, a large amount of material chips of about room temperature are charged from the hopper, so that the temperature of the screw supply section becomes lower. As a result, the material chips fed from the hopper always have a lower temperature than the intended temperature because the screw has a low temperature, and the preheating state of the material chips in the screw supply unit cannot be controlled appropriately. Therefore, melting in the compression section is delayed or difficult, and the rotational load pressure of the screw increases, and the metering tends to become unstable. Therefore, when a large amount of material chips were charged at one time at the start of molding, it was necessary to wait for a long time until the temperature of the screw supply section was recovered. Therefore, do not put a large amount of material chips at the beginning of molding,
It was necessary to charge the material chips in several batches with a certain time interval to prevent the temperature drop in the screw supply section.

When molding a large product having an injection weight of 50% or more of the injection function, a large amount of material chips are supplied from the hopper in a fixed cycle, so the temperature of the screw supply section is always low. There was a possibility that the screw rotation load pressure increased and the weighing became unstable.

The present invention has been made to solve the above problems, and is caused by poor preheating of the molding material at the screw supply portion at the start of molding or when molding a large product. The purpose is to prevent measurement instability due to an increase in screw rotation load pressure.

[0009]

A method for stabilizing the weighing of a metal injection molding machine according to the present invention comprises a screw feeding section consisting of a feeding section, a compression section and a weighing section from the hopper side to the tip.
It is characterized by heating directly at the start of molding or when molding a large product.

A metal stabilizing apparatus for a metal injection molding machine according to the present invention forms a screw supply section consisting of a supply section, a compression section and a metering section from the hopper side toward the tip at the start of molding or for molding a large product. In this case, a heating means for directly heating is installed in the molding machine.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described based on examples with reference to the drawings.

In FIG. 1, the reference numeral 1 designates a cylinder barrel in which a screw 2 is provided. The screw 2 rotates in the cylinder barrel 1 to feed a material chip 15 as a molding material to the front, and moves forward at a high speed so that the molten material stored in a storage chamber 6 formed in the front is put into a mold 9. To eject.

A nozzle 3 is attached to the front end of the cylinder barrel 1, and a supply port 1a for supplying a material chip 15 to the cylinder barrel 1 is provided at the rear end.
The hopper 1 is provided above the supply unit 1a via the feeder 10.
1 is attached. A heater 4 is attached to the outer peripheral wall of the cylinder barrel 1.

A backflow preventing ring 5 is provided at the tip of the screw 2 to open a flow path between the screw 2 and the storage chamber 6 at the time of measurement and close the flow path at the time of injection. A screw drive device 7 for advancing the screw 2 at a high speed and a motor 8 for rotating the screw 2 are connected to the rear end of the screw 2.

Generally, the screw can be divided into a supply section, a compression section, a metering section, etc. from the hopper side toward the tip.

In the present embodiment, a through passage 12 is formed inside from the rear end portion of the screw 2 to the supply portion.
Heating medium piping for supplying heating medium such as oil or gas to the pipe 1
3 is provided. A heating medium temperature controller 14 is connected to the heating medium pipe 13 for heating.

Next, the operation will be described.

When the mold 9 is closed, the molten material measured in the storage chamber 6 in the cylinder barrel 1 is injected into the mold 9 by the high speed advance of the screw 2. After that, rice grain-sized material chips 15 start to be fed from the feeder 10 to the supply section of the screw 2, and at the same time, the screw 2 rotates and the material chips 15 put in the cylinder barrel 1 are sent to the front of the cylinder barrel 1. Cylinder barrel 1 in the meantime
The heat is transmitted from it and gradually melts. Screw 2 is
While rotating, it retreats to form the storage chamber 6 in the front, and collects the molten material.

The amount of molten material required for the next injection is stored in the storage chamber 6.
The rotation of the screw is stopped at the point where it is stored in, and the molding material is heated and held at the respective screw positions in the solid state and the molten state until the next measurement is started. The temperature of the cylinder barrel 1 at this time is 500-
While the temperature is about 600 ° C., the supply part of the screw 2 into which the material chip 15 at about room temperature is always put is in a state of being deprived of heat by the molding material. Therefore, when molding a large product having an injection weight of 50% or more of the injection functional force, the supply part of the screw 2 has a temperature higher than the temperature of the cylinder barrel 1 by 10%.
The temperature may be as low as 0 ° C or higher. Therefore, by heating the screw 2 from the inside by flowing a heating medium whose temperature is controlled by the heat medium temperature controller 14 into the through passage 12 that has passed to the inside of the screw 2 of the supply part, the temperature of the screw supply part is increased. It does not decrease and is kept at a certain temperature. As a result, the shortage of residual heat of the material chip 15 is eliminated even when molding a large product.

At the start of molding, the material chip 15 is fed from the feeder 10 into the supply part of the screw 2, and at the same time, the screw 2 is rotated, and the material chip 15 put in the cylinder barrel 1 is in front of the cylinder barrel 1. The heat is transferred from the cylinder barrel 1 during that time and gradually melts. Then, when a certain amount of material chips 15 is put into the cylinder barrel 1, the rotation of the screw 2 is stopped, and the molding material in the cylinder barrel 1 is in a solid state and a melting process at each screw position. In each of the state and the molten state, it is heated and held until the first weighing starts. At this time, the temperature of the cylinder barrel 1 is about 500 to 600 ° C., whereas the supply portion of the screw 2 into which the material chip 15 at about room temperature is always charged is always in a state of being deprived of heat by the material chip 15. The temperature may be 100 ° C. or more lower than the temperature of the cylinder barrel 1.

Therefore, when molding is performed without waiting for the temperature of the screw 2 to recover, preheating of the material chip 15 in the supply part of the screw 2 is insufficient and the material chip 15 is fed to the screw compression part in that state. Therefore, melting in the compression section may be delayed or difficult, and the screw rotation load pressure may increase and the metering may become unstable.

Therefore, if the supply part of the screw 2 is heated from the inside as in the case of molding the large-sized product, the time required for temperature recovery of the supply part of the screw 2 is shortened and the molding can be started immediately. Like

In the above-described embodiment, in order to heat the supply part of the screw 2, the heating medium pipe 13 for heating is installed inside the supply part of the screw 2 to supply the heating medium. An induction heater or an infrared heater may be installed inside the supply part of the screw 2.

[0024]

As described above, according to the present invention, it is possible to prevent the temperature of the screw supply portion from decreasing.
A large product with an injection weight of 50% or more of the screw injection function can be stably molded. Also, at the start of molding,
Even if a large amount of material chips are thrown in at one time, the temperature of the screw supply part is less decreased and the recovery is faster, so that the waiting time can be shortened.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view showing a metal injection molding machine having a screw internal heating means according to an embodiment of the present invention.

FIG. 2 is a sectional side view showing a conventional metal injection molding machine.

[Explanation of symbols]

1 cylinder barrel 1a Supply port 2 screws 3 nozzles 4 heater 5 Backflow prevention ring 6 storage room 7 Screw drive 8 motor 9 mold 10 feeders 11 hoppers 12 through roads 13 Heating medium piping 14 Heat medium temperature controller 15 material chips 16 molded products

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Matsuyama 1-6-1, Funakoshi Minami, Aki-ku, Hiroshima City, Hiroshima Prefecture Japan Steel Works, Ltd. (56) Reference JP 2002-66712 (JP, A) Japanese Unexamined Patent Publication No. 9-1612 (JP, A) Japanese Unexamined Patent Publication No. 9-48053 (JP, A) Japanese Unexamined Patent Publication 2001-179416 (JP, A) Japanese Unexamined Patent Publication 2002-144000 (JP, A) (58) Fields investigated (Int.Cl) . ^7, DB name) B22D 17/20

Claims (6)

(57) [Claims] 1. A method for directly heating a screw (2) supply unit including a supply unit, a compression unit, and a metering unit from the hopper side toward the tip at the start of molding or when molding a large product. A method for stabilizing the weighing of a characteristic metal injection molding machine. 2. Heating for directly heating a screw (2) supply part including a supply part, a compression part, and a metering part from the hopper side toward the tip at the start of molding or when molding a large product. A measuring and stabilizing device for a metal injection molding machine, characterized in that the means is installed in a molding machine. 3. The heating means is a heating medium pipe for heating (13) for supplying a heating medium to the inside of the supply part of the screw (2).
The measuring and stabilizing device for a metal injection molding machine according to claim 2, further comprising: 4. The weighing and stabilizing device for a metal injection molding machine according to claim 2, wherein said heating means has a rod-shaped heater inserted inside the supply portion of the screw (2). 5. The weighing and stabilizing device for a metal injection molding machine according to claim 2, wherein the heating means has an induction heater inserted inside the supply part of the screw (2). 6. The weighing and stabilizing device for a metal injection molding machine according to claim 2, wherein the heating means has an infrared heater inserted inside the supply portion of the screw (2).