JP3139570B2 - Nozzle closing valve for metal injection molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a nozzle closing valve for closing a material flow path between a mold and an injection machine.

[0002]

2. Description of the Related Art Conventionally, injection machines of an injection molding apparatus include a type having a stop valve in a nozzle and a type not having a stop valve. And the so-called open type without a stop valve is often found in relatively small equipment, and the leakage of material during metering or before and after injection is caused by the solidification of the material at the nozzle tip due to the temperature drop, or the decrease in fluidity, etc. It is intended to prevent the leakage and allow some leakage of the material. On the other hand, in the case of a type in which a stop valve is provided in a nozzle to prevent accurate metering or leakage before and after injection, a valve mechanism is often provided in the nozzle, and the valve mechanism in the nozzle is formed of, for example, resin molding. Injection molding equipment has been put to practical use and has a proven track record. Further, in the case of a molding machine for metal casting, a type using a piston type valve for a supply port or an injection port of molten metal is also known as such a valve mechanism.

[0003]

However, among the above-mentioned types, the open type without a stop valve allows the device to be constructed very easily, but on the other hand, it is difficult to form an oxidizing device such as a magnesium alloy. In the case of molding with a thixomold using an easy-to-use metal material, it easily reacts with the air in the outside world and is easily oxidized, which tends to cause inconveniences such as clogging of nozzles or deterioration of product quality.
Also, material leakage was potentially dangerous. On the other hand, in the case of the type in which the valve mechanism is provided in the nozzle, the maintainability is poor, the durability of the valve mechanism is deteriorated due to the high temperature region, and further, there is a problem that material stays in the valve mechanism. there were. Such a problem has become even more serious in the case of a magnesium alloy which is easily oxidized as described above. Further, in the case of a valve mechanism in which a piston type valve is used for a supply port and an injection port of the molten metal, the molten metal is easily inserted into a slide portion or the like, and there is a problem in operation reliability and durability.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a nozzle closing valve for opening and closing a material flow path between an injection machine and a mold by using a rotary mechanism between the injection machine and the mold. A rotatable valve main body was provided, and the valve main body was provided with a contact surface capable of closely contacting each of a tip end of the injection machine and a material supply inlet on the mold side. Then, a through hole is formed to connect the contact surfaces and communicate the material flow path on the injection machine side and the material flow path on the mold side. The through hole has a tapered shape with a small diameter on the injection machine side and a large diameter on the mold side. did. In addition, the contact surface has a spherical shape.

[0005]

The material passage is opened and closed by rotating the valve body by the rotating mechanism to change the communication state of the tapered through hole. The flow path is shut off while the material is being measured, and the flow path is opened in the injection process. When the molded article solidifies in the mold after injection, the mold is released, but the solidified body in the through hole is extracted together with the molded article. In other words, the through-hole has a large diameter on the mold side, and thus is pulled out as it is. Then, immediately after that, if the valve body is rotated to close the flow path, the contact between the molten metal remaining on the injection machine side and the air is cut off, and there is no problem such as oxidation. In addition, since the through-hole tapers toward the injection machine, it is effective in preventing backflow. Further, such a valve mechanism has good maintainability from the outside.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a nozzle closing valve of a metal injection molding apparatus according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is an overall front view of a metal injection molding apparatus of the present invention, FIG. 2 is an enlarged sectional view of a nozzle closing valve, and FIG. 3 is a sectional view taken along line AA of FIG. FIG.

First, a general outline of a metal injection molding apparatus will be described with reference to FIG.

The metal injection molding machine includes a mold 3 connected to one end of the injection machine 1 via a nozzle closing valve 2 and a material supply chamber 4 connected to the other end of the injection machine 1. The ingot-shaped metal material W supplied from 4 is processed to form a semi-solid slurry, and is injected into the mold 3.

The injection machine 1 includes a heating cylinder 7 supported by a cylinder holder 6 on a support table 5 and a screw 8 provided in the heating cylinder 7. A coil 10 and a heat insulating material 11 are provided and cover the periphery. The inside of the heating cylinder 7 is configured as a material flow path 9, and a nozzle portion 1 as a tip of an injection machine is provided at the tip of the heating cylinder 7.
2, and the tip end surface of the nozzle portion 12 has a curved concave shape 12a as shown in FIG.

On the other hand, the screw 8 has a spiral groove provided at least in front of the material supply chamber 4, and a stop valve 13 is provided at the tip of the spiral groove.
The lower end of the material supply chamber 4 faces the upper end of the rear end of the spiral groove. The rear extension of the screw 8 is connected to a screw rotation motor 14 so as to be rotatable.

The screw rotation motor 14
Is mounted on the support base 5 via a slide guide 15, and is slidable back and forth (left and right in FIG. 1).

The rear end of the screw 8 extends further rearward than the screw rotating motor 14 via a coupling, and is connected to a screw longitudinal movement cylinder unit 16. Therefore, the screw 8 and the screw rotating motor 14 both move forward and backward by the operation of the screw longitudinal movement cylinder unit 16.

The sliding portion between the heating cylinder 7 and the screw 8 is provided with a sealing portion such as a metal packing or a metal seal at an appropriate position, so that the inside of the heating cylinder 7 has a sealed structure which avoids contact with the outside. I have.

A ceramic plate 17 is provided at the joint between the support base 5 and the cylinder holder 6, and a proper place on the support base 5 side and a proper place behind the heating cylinder 7 are cooled by a cooling coil or the like. This is because the cylinder holder 6 is heated more than a normal injection molding machine, so that adverse effects on other devices and the like are avoided.

Next, the outline of the material supply chamber 4 will be described.

The material supply chamber 4 is partitioned from above into an ingot introduction chamber 21, a heating chamber 22, a heat insulation chamber 23, and a chop chamber 24. A first shutter 25 is provided between the introduction chamber 21 and the heating chamber 22. And a second shutter 26 is provided between the heating chamber 22 and the heat retaining chamber 23 so as to be able to shut off. In addition, each room 21, 22, 2
Both metal seals 3 and 24 use a metal packing and a metal seal at appropriate places, and have a sealed structure.

The first and second shutters 25, 2
The opening and closing cylinder units 6 and 28 can be moved forward and backward by the respective opening and closing cylinder units 27 and 28 so as to open and close in a direction perpendicular to a material supply path formed in a vertical direction.

The introduction chamber 21 is a chamber for supplying an ingot W. The introduction chamber 21 is configured so that the temperature inside the chamber can be kept constant by a heater provided therearound, and has an ingot holder that can be lowered toward the heating chamber 22. I have.

The heating chamber 22 is a chamber for heating the ingot W, and has a ceramic sleeve on which a heating coil is wound on a second shutter 26 on which the ingot W is placed.

An inert atmosphere conversion mechanism 30 is connected between the heating chamber 22 and the introduction chamber 21. The inert atmosphere generating mechanism 30 includes a vacuum pump 31 for evacuating the air in the room and a gas cylinder 32 for supplying an inert gas such as argon, nitrogen, carbon dioxide or the like into the room. It is provided to maintain good quality.

The heat-retaining chamber 23 is a chamber for preventing the temperature from lowering until the heated ingot W is chopped. The chamber is longer than the chamber, and is also considered to serve as a temporary stock room for the material or a chamber for regulating the supply amount.

The lower chop chamber 24 is a chamber for cutting and crushing the ingot W having reduced deformation resistance and supplying it to the screw 8 in the lower heating cylinder 7. , Kneader type 2-axis chopper 3
3 are provided.

The biaxial chopper 33 has a pair of rotating bodies having spiral blades facing in opposite directions. The rotating bodies are rotated in opposite directions to engage the spiral blades in a non-contact state, and the ingot W is moved downward. It is crushed so as to draw in. The two-axis chopper 33 rotates in synchronization with the screw 8 and also serves as a stopper for the ingot W when stopped.

The chop chamber 24 is also heated and held by a heater to prevent the temperature from dropping.
The three-drive hydraulic or electric motor is located far away from the device to avoid adverse effects of heat.

On the other hand, the mold 3 adjacent to the nozzle closing valve 2 described later has a pair of fixed molds 34 and a movable mold 35, and a material supply inlet 36 is provided at the center of the fixed mold 34. . The front surface of the material supply inlet 36 is
As shown in FIG. 2, a tapered runner 37 serving as a material flow path provided inside has a spherical concave shape 36a, and communicates with a product shape portion 38 between the two dies 34, 35 as shown in FIG. The taper of the runner 37 is
It has a shape that the side expands.

Next, the nozzle closing valve 2 will be described.

The nozzle closing valve 2 is provided on a rotary bearing 40 and includes a valve body 41 rotatable about a vertical axis and a rotating mechanism for driving the valve body 41 to rotate. The rotating mechanism is not shown. It is driven by a motor, a cam or the like.

As shown in FIG. 2, the valve body 41 is made of, for example, a metal material or fine ceramic and has a substantially spherical shape. The valve body 41 has a nozzle 12 on the injection machine 1 side and a material supply inlet 36 on the mold 3 side. The contact surfaces 42a and 42b are provided in close contact with the concave shapes 12a and 36a.

The opposed contact surfaces 42a, 4a
2b, and a through-hole 43 is provided to allow the material flow path 9 on the injection machine 1 side to communicate with the runner 37 on the mold 3 side.
The side has a large diameter tapered shape. Then, the material flow path is opened and closed as shown in FIGS. 2 and 3 by rotating around the vertical axis. However, the rotation need not be 90 degrees as shown in FIG. Any angle may be used.

A heater 44 for controlling the temperature is wound around the valve body 41 to appropriately prevent the nozzle temperature from lowering.
Alternatively, the temperature of the molten metal is prevented from changing. The periphery is covered with a heat insulating material 46.

A pair of scrapers 45 are provided in the vicinity of the nozzle portion 12 and the material supply inlet portion 36 at the same height as the through-hole 43 to scrape off the metal material adhering when the valve body 41 rotates. Like that.

The operation of the valve closing valve 2 will be described. Introducing chamber 21 by inert atmosphere generating mechanism 30
When each chamber and the like is evacuated and inactivated via the heating chamber 22 and the heating chamber 22, an ingot W of, for example, a magnesium alloy or the like is supplied into the introduction chamber 21 and processed.

That is, the ingot W is heated in the heating chamber 22 by the power, frequency, time, and the like set in advance by a test until it reaches the semi-solidified region, and is then chopped by the biaxial chopper 33 in the chop chamber 24. .
That is, in the heated ingot W, the deformation resistance is reduced from about several hundredths to several thousandths.
The helical blades of the two rotating bodies are torn and crushed and cut.

The cut metal material is supplied into the spiral groove of the screw 8 in the heating cylinder 7, and the solid-state dendrite is divided and granulated by the strong stirring action of the screw 7 and the heating from the heating cylinder 7. It is transported forward as a semi-solid slurry.

At this time, the nozzle closing valve 2 closes the flow path as shown in FIG.
Since the screw 3 is open, the screw 8 retreats by the pressure of the slurry extruded forward of the screw 8. Then, a predetermined amount of slurry is stored in front of the screw 8.

When a predetermined amount of slurry is stored, injection is performed. That is, when the stop valve 13 in front of the screw 8 is closed and the nozzle closing valve 2 is simultaneously rotated to communicate the material flow path 9 of the injection machine 1 with the runner 37 on the mold 3 side, the cylinder unit 16 Screw 8
Is rapidly extruded, and a metal material is injected and filled into the product shape portion 38 of the mold 3.

At the time of this injection, the nozzle closing valve 2 is heated by a temperature control heater 44 as necessary.
In addition to smoothing the flow of the material at the time of injection, heating is stopped after the injection is completed.

When coagulated as it is,
The solidified state proceeds from the product shape portion 38 toward the runner 37 on the upstream side, and finally reaches a portion inside the through hole 43 of the nozzle closing valve 2.

Then, after opening the mold 3 at that time,
For example, when the molded body is pushed to the left in the figure by an extrusion pin (not shown) provided on the fixed mold 34, the runner 37 and the solidified body in the through hole 43 are simultaneously extracted with the product shape part 38.

Immediately after being extracted, the nozzle closing valve 2
Is turned to shut off the tip of the nozzle portion 12 to shut off the inside of the heating cylinder 7 from the outside air. Therefore, the oxidation of the metal material remaining in the material flow path 9 does not progress, and the molding quality in the next molding shot does not deteriorate.

During the rotation of the nozzle closing valve 2, the through hole 43
The scraping of the material adhering to the vicinity of the outlet by the scraper 45 is as described above.

Next, the type of another embodiment shown in FIG. 4 will be described.

In this apparatus, a plunger injection machine 50 is provided between a mold 60 and a nozzle closing valve 2 so that the kneading slurry and the injection into the mold are separately performed. . The plunger injector 50 includes a plunger sleeve 52 having a ceramic sleeve 51 inside, and a plunger tip 53 slidable in the plunger sleeve 52. The periphery of the plunger sleeve 52 is covered with a heater 54 for keeping heat. ing.

A heat insulating material 55 is provided around the heater 54 and the plunger sleeve 5 is provided.
A plurality of thermocouples for temperature control are provided at two predetermined locations.
The plunger sleeve 52 is a semi-closed sleeve without a pouring port opened to the outside like a so-called cold chamber sleeve. In the embodiment, the ceramic sleeve 51 is fitted on the inner surface to keep the temperature and to improve the durability, but it may be coated with ceramic.

The plunger sleeve 52 is oriented vertically, and the plunger tip 53 is configured to slide up and down. A material supply inlet 56 is provided on the lower side surface of the plunger sleeve 52, and the inner tapered shape is provided. Material passage 57 is open toward the inside of the sleeve 52. Further, on the front surface of the material supply inlet portion 56, a spherical concave shape 56 which can be brought into close contact with the spherical nozzle closing valve 2 is provided.
a is formed. Although the plunger sleeve 52 is oriented vertically in the embodiment, the plunger sleeve 52 may be oriented horizontally.

The end of the plunger sleeve 52 is
Connected to 0. The mold 60 includes a pair of mold support frames 61, 62, a fixed mold 63, a movable mold 64, and a shunt 65 held by the mold support frames 61, 62. It communicates with a product shape part 66 between the two dies 63 and 64 via a child 65. The configurations of the nozzle closing valve 2, the screw injector 1, and the like are the same as those in the above-described example.

The outline of the operation of the injection molding machine thus configured is as follows. First, with the nozzle closing valve 2 closing the material flow path, the screw 8 rotates to push the slurry forward.

When a certain amount of slurry is accumulated, the stop valve 13 in front of the screw 8 which has been opened is closed, and at the same time, the nozzle closing valve 2 rotates to communicate the flow path.

Thereafter, the screw 8 advances and the slurry accumulated in the front is pushed into the plunger sleeve 52 in a short time, and then the flow path is shut off by the nozzle closing valve 2 and injected by the plunger tip 53. At this time, since the semi-solidified slurry remains in the through hole 43 of the nozzle closing valve 2, the internal slurry is prevented from leaking to the outside during rotation.
For example, means such as providing a cover member made of ceramic or the like capable of closing each end of the through hole 43 along the rotation direction is employed. In this case, the temperature is constantly heated by the temperature control heater 44 so as not to solidify the internal slurry at the same time.

If the injection is performed in such a manner that the flow path on the screw injection machine 1 side is shut off, even if the mold is opened to take out the product after solidification, the metal material upstream of the nozzle closing valve 2 is air. Oxidation can be effectively prevented without contacting Further, since the plunger sleeve 52 is also a semi-closed sleeve that does not come into contact with the outside as described above, the effect of preventing oxidation is high.

Further, by performing the kneading and injection of the materials in separate apparatuses as described above, it becomes extremely easy to set, for example, the temperature management and the time management during the kneading and the injection to optimal conditions, respectively. It can contribute to improvement of molding quality. In addition, since the pressure at the time of injection does not affect the screw 8 side, strict performance is not required for the structural materials such as the heating cylinder 7 and the screw 8, and the kneading and injection are performed simultaneously with the screw 8. Since there is no need to simultaneously move the screw 8 and the rotation motor 14 at high speed, it is possible to provide an energy-saving compact device.

[0052]

As described above, the nozzle closing valve of the present invention
Since it is rotatably arranged between the injection machine and the mold, and the communication of the material flow path is blocked or opened by the tapered through hole, not only can the material leak be prevented, but also the outside air can be prevented. As a result, the material can be reliably shut off, thereby preventing impurities from being mixed by oxidation. For this reason, the quality of a molded article can be improved. In addition, the structure is simple, and it is not always in a high temperature state as in the case where it is installed inside the nozzle, and it is easy to maintain from the outside, so in terms of maintainability, durability, reliability, etc. It is superior to the conventional valve structure.

[Brief description of the drawings]

FIG. 1 is an overall front view of a metal injection molding apparatus according to the present invention.

FIG. 2 is an enlarged sectional view of a nozzle closing valve.

FIG. 3 is a cross-sectional view taken along line AA in FIG.
Rotated state diagram

FIG. 4 is a partial view of an injection molding apparatus according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection machine 2 Nozzle closing valve 3 Die 9 Material flow path 36 Material supply inlet 37 Runner 41 Valve main body 42a, 42b Contact surface 43 Through hole W Ingot

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-220801 (JP, A) JP-A-2-163572 (JP, A) JP-A-2-36666 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) B22D 17/30 B22D 17/00 B22D 17/20 B29C 45/23

Claims (1)

(57) [Claims] A nozzle closing valve for opening and closing a material flow path between an injection machine and a mold, the nozzle closing valve includes a valve body provided between the injection machine and the mold, and a valve body provided between the injection machine and the mold. A rotation mechanism for rotating around a rotation axis is provided, and the valve body includes:
While providing a contact surface that can be in close contact with each of the tip of the injection machine and the material supply inlet on the mold side, the contact surfaces are connected, and the material flow path on the injection machine side and the mold side are connected. Metal, characterized in that a through hole for communicating the material flow path is formed, the through hole is formed in a tapered shape with a small diameter on the injection machine side and a large diameter on the mold side, and the contact surface is formed in a spherical shape. Nozzle closing valve for injection molding equipment.