JP2001205417A - Injection molding method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding method and device which prevent a metering defect and shorten molding time. SOLUTION: This device has a metering and transferring means(6) consisting of a metering cylinder (3) which is supplied with raw material chips (1) from its one end, a metering screw (4) which is disposed in the metering cylinder (3) and meters and transfers the raw material chips (1) and a preheating means (5) which preheats the raw material chips (1) and a melting and injecting means (10) consisting of an injection cylinder (7) which is connected to the other end of the metering cylinder (3), an injection piston (8) which is disposed in the injection cylinder (7) and moves back and forth within the injection cylinder (7) and a high-speed heating means (9) which is mounted at the injection cylinder (7) and heats the raw material chips (1) at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method and apparatus which heats and melts a supplied raw material chip in a cylinder of an injection molding machine and injects it into a mold for molding.

[0002]

2. Description of the Related Art In general, there are a die casting method and a thixomolding method as injection molding methods of a light alloy such as a magnesium alloy. The die casting method uses a light alloy ingot of magnesium or the like as a molding material, and supplies the molten metal melted in the furnace to the sleeve by an automatic water heater or manual pumping, etc., and the reciprocating motion provided in the sleeve The molten metal is injected and filled into the mold cavity by advancing a possible plunger at high speed.

[0003] On the other hand, the thixomolding method uses a light alloy chip obtained by cutting a light alloy ingot of magnesium or the like as a raw material and heats it in a cylinder of an injection molding machine to obtain fluidity without contact with the atmosphere. Is made into a semi-solid slurry (thixotropic state) with good quality and is injected into a mold as it is and molded. Specifically, as shown in FIG. 7, a light alloy tip 30 having a diameter of about 3 to 5 mm
It is supplied into the cylinder 32 via the hopper 31, and is transferred forward by rotating a screw 33 which is reciprocally mounted in the cylinder 32. While the light alloy chip 30 is transferred forward in the cylinder 32 by the rotation of the screw 33, the light alloy chip 30 is brought into a molten state by the heating of the electric heater 34 attached to the outer peripheral portion of the cylinder 32. At this time, the screw 33 is moved to the hopper 3 at a constant speed.
When the screw 33 is retracted to the first side and a predetermined retraction stroke is reached, the rotation and retraction of the screw 33 is terminated, and a predetermined amount of the molten material measured in a storage portion formed in front of the screw 33 is advanced by the screw 33 to thereby advance the nozzle. It is injected through a mold 35 into a mold cavity 37 formed in a mold 36.

[0004]

As described above, the conventional injection molding method has the following problems. In the die casting method, when the molten metal is supplied from the furnace to the sleeve, in the case of an automatic water heater, the molten metal supply error becomes about 5% or more due to fluctuations in the liquid level, the molten metal temperature, and the variation of the hot water supply device. There is a problem that variations occur.
For this reason, when the supply amount of the molten metal is small, molding defects such as defective filling and hot wrinkling occur in the molded product. On the other hand, when the supply amount of the molten metal is large, excessive burr occurs in the molded product, There are problems such as lack of accuracy. Further, in the case of manual pumping, since the measurement is carried out by visual measurement, the precision of supplying the molten metal is further low.

On the other hand, in the thixomolding method, since the transfer, heating, and melting of the raw material chips are simultaneously performed in a single cylinder, the transfer and melting behavior of the raw material chips in the cylinder becomes complicated. For example, in the case of a magnesium alloy, the root side of the cylinder is approximately 500 ° C. of the solidus temperature.
The tip side is set to the liquidus temperature of about 600 ° C, and a normal temperature magnesium alloy chip and a forming temperature molten magnesium alloy are continuously placed in a single cylinder from the root side to the tip side. It will exist.

As a result, there is a problem that excessive rotation resistance is generated at the time of screw rotation due to variations in the state of transfer and melting of the raw material chips, resulting in poor measurement of the molten raw material.
As with the die casting method, when the weighing failure occurs, when the supply amount of the molten metal is small, molding defects such as poor filling and hot wrinkles occur in the molded product. There are problems such as the generation of burrs and lack of dimensional accuracy. Also, when molding large products or shortening the molding time, high melting capacity is required.However, in order to increase the heating area of the cylinder, the screw and cylinder become longer, and a large electric heater is added. There is a need to.

An object of the present invention is to solve such a problem and to provide an injection molding method and apparatus which can prevent weighing errors and shorten the molding time.

[0008]

In order to solve the above-mentioned problems, according to the present invention, the supplied material chips (1) are heated and melted in a cylinder of an injection molding machine. In the injection molding method in which the raw material chips (1) are pre-heated, weighed and transferred, and the transferred raw material chips (1) are heated in the injection molding method of performing injection molding into the molds (11a, 11b). It is characterized in that it is melted and separated into a part to be injected into the mold (11a, 11b).

According to the second aspect of the present invention, the supplied raw material chips (1) are heated and melted to form the molds (11a, 11b).
In an injection molding device (2) that performs injection molding into the inside,
A measuring cylinder (3) to which a raw material chip (1) is supplied from one end; a measuring screw (4) arranged in the measuring cylinder (3) for measuring and transferring the raw material chip (1); ), Pre-heating means (5) for pre-heating, a metering transfer means (6), an injection cylinder (7) connected to the other end of the measuring cylinder (3), and an injection cylinder (7). A melt injection means, comprising: an injection piston (8) installed and reciprocated in an injection cylinder (7); and a melt heating means (9) attached to the injection cylinder (7) and melting and heating the raw material chip (1). (10), the raw material chips (1) are pre-heated by the measuring and transferring means (6),
The melt injection means (10) is supplied to the melt injection means (10).
The raw material chip (1) supplied in (1) is heated and melted and injected into the molds (11a, 11b).

According to a third aspect of the present invention, in the injection molding apparatus according to the second aspect, the preheating means (5) pre-heats the raw material chips (1) in the measuring cylinder (3) to a temperature at which the chip shape can be maintained. It is characterized by heating. According to a fourth aspect of the present invention, in the injection molding apparatus according to the second or third aspect, the melt heating means (9) turns the raw material chip (1) into a molten state after the end of the raw material supply by the measuring and transferring means (6). It is characterized by heating to a temperature.

According to a fifth aspect of the present invention, in the injection molding apparatus according to any one of the second to fourth aspects, the injection piston (8), after the measurement is completed, heats the raw material chip (1) by the high-speed heating means (9). The material chip (1) moves at a low speed to the disposed heating and melting section, and moves at a high speed when the raw material chip (1) is melted and injected. According to a sixth aspect of the present invention, in the injection molding apparatus of any of the second to fifth aspects, the melt heating means (9) is a high-speed heating means such as an induction heating apparatus.

According to a seventh aspect of the present invention, in the injection molding apparatus according to any one of the second to sixth aspects, the injection molding apparatus (1) includes an injection cylinder (7) disposed in a vertical direction. It is a vertical injection molding apparatus in which dies (11a, 11b) are arranged on the upper side of (7). According to an eighth aspect of the present invention, in the injection molding apparatus according to any one of the second to seventh aspects, the raw material chip (1) is a light alloy chip such as a magnesium alloy.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the metal injection molding machine of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional configuration view of a metal injection molding apparatus showing an embodiment of the present invention, and FIG.
FIG. 3 is a configuration diagram showing a state of a heating and melting step in the apparatus of FIG. 1, and FIG.
Is a configuration diagram showing a state of an injection holding pressure process in the apparatus of FIG. 1, FIG. 5 is a configuration diagram showing a state of a product removal and measurement step in the apparatus of FIG. 1, and FIG. FIG. In the metal injection molding apparatus of the present embodiment, the supplied raw material chip 1 is heated and melted,
In an injection molding apparatus 2 for performing injection molding into the molds 11a and 11b, the raw material chips 1 are preheated, measured and transferred, and the transferred raw material chips 1 are melted and melted. The raw material chips 1 are preliminarily heated by the measuring and transferring means 6, measured and transferred to the melting and injection means 10, and transferred by the melting and injection means 10. The obtained raw material chip 1 is melted at a high speed and injected into the dies 11a and 11b. The material chip 1 is a light alloy chip such as a magnesium alloy such as AZ91D.

The measuring and transferring means 6 includes a measuring cylinder 3 disposed horizontally as shown in the figure, a measuring screw 4 disposed in the measuring cylinder 3, and performing a measuring and transferring of the raw material chips 1 by a rotational drive by a motor. And preheating means 5 for performing preheating. A hopper 12 for supplying the raw material chips 1 is provided at one end of the measuring screw 4, and Ar gas is supplied from the piping together with the raw material chips 1 to prevent oxidation. The preheating means 5 is, for example, an electric heater, and preheats the raw material chip 1 to a temperature at which the chip shape can be maintained, that is, a solidus temperature ± 20 ° C. For example, in the case of AZ91D among magnesium alloys, since the solidus temperature is about 470 ° C, preheating is performed so as to be in the range of 450 to 490 ° C.

The melt-injection means 10 is disposed vertically, and the injection cylinder 7 is vertically connected to the other end of the measuring cylinder 3.
And an injection piston 8 arranged in the injection cylinder 7 and capable of reciprocating up and down, and a high-speed heating means (melting heating means) mounted around the upper side surface of the injection cylinder 7 to heat the raw material chip 1 at high speed. 9 As described above, in the present embodiment, the vertical injection molding apparatus has the injection cylinder 7 in the vertical direction.

The other end of the measuring cylinder 3 is opened and communicated with the lower side surface of the injection cylinder 7 to form a raw material supply port 13, and the raw material chips 1 are supplied from the measuring and transferring means 6. The high-speed heating means 9 is, for example, an induction heating device. Further, a thermocouple 14 is provided together with the high-speed heating means 9, and detects the temperature of the molten raw material chip 1 in the injection cylinder 7 and controls the high-speed heating means 9 to a predetermined temperature.
The injection piston 8 stands by below the raw material supply port 13 at the time of metering, and transfers the raw material chips 1 supplied from the measuring and transferring means 6 upward. At the time of injection into the dies 11a and 11b, it is controlled to rise at high speed. After the injection, the injection piston 8 is lowered to a position below the original material supply port 13.

The high-speed heating means 9 heats the raw material chips 1 to a temperature at which the raw material chips 1 are brought into a molten state and a liquidus temperature ± 40 ° C. after the raw material supply by the measuring and transferring means 6 is completed. For example, in the case of AZ91D among magnesium alloys, the liquidus temperature is about 5
Since it is 95 ° C., it is heated to 555-635 ° C. The injection cylinder 7 is connected to a pipe for Ar gas, and is supplied with Ar gas as needed to prevent oxidation. A fixed mold 1 is provided at the tip of the nozzle of the melt injection means 10.
The mold cavity 15 is formed between the movable mold 1a and the movable mold 11b. Mold cavity 1
Numeral 5 is connected to a pipe of a vacuum device, and the vacuum device performs evacuation during the period from the measurement process to the end of the injection and pressure holding process.

Next, the injection molding operation of this embodiment will be described with reference to FIGS. As shown in FIG. 2, when the raw material chips 1 are supplied from the hopper 12 together with the Ar gas into the measuring cylinder 3, the measuring screw 4 is driven to rotate, and the supplied raw material chips 1 are supplied to the left side of the drawing. Mouth 1
3 and is supplied to the inside of the injection cylinder 7. At this time, the raw material chips 1 are transferred through the measuring cylinder 3 while being preheated by the preheating means 5 to such an extent that the shape of the raw material chips 1 is maintained.

In the injection cylinder 7, the injection piston 8 stands by at a position below the raw material supply port 13, and a predetermined amount of the raw material chips 1 is deposited on the upper part of the injection piston 8.
The supply amount of the raw material chips 1 to the injection cylinder 7 is measured and controlled by the rotation time of the measuring screw 4 in the measuring cylinder 3. When the supply of the predetermined amount of the raw material chips 1 is completed, FIG.
As shown in the figure, the rotation of the measuring screw 4 of the measuring cylinder 3 is completed, and at the same time, the injection piston 8 is set at 0.1 to 0.5 m /
At a low speed of s, it rises to the heating and melting section where the high-speed heating means 9 is installed. The raw material chip 1 has a temperature at which a predetermined molten state is obtained in a short time of 5 to 30 seconds, that is, a liquidus temperature ± 4.
Heat to 0 ° C. At this time, the temperature of the raw material chip 1 is indirectly measured by a thermocouple 14 attached to the injection cylinder 7, and when the temperature of the raw material chip 1 is lower than the predetermined temperature, the high-speed heating means is set to the predetermined temperature. 9 is controlled.

When the raw material chip 1 is in a molten state, as shown in FIG. 4, the injection piston 8 moves up to the dies 11a and 11b at a high speed of 0.5 to 5.0 m / s, and the molten metal is filled in the mold cavity. 15 is injected and filled. After a lapse of a cooling time of about 1 to 10 seconds after the completion of the injection, filling, and pressure holding, the injection piston 8 immediately descends to its original position, that is, below the raw material supply port 13, and the measurement of the next shot is started. You. After the cooling time is over, as shown in FIG. 5, the mold is opened, the product is ejected, and the molded product is taken out. Then, the steps of weighing, heating and melting, injection holding pressure, product taking out, and weighing shown in FIGS. Next, the molding cycle time will be described with reference to FIG.

When a large automobile part was molded by an injection molding apparatus having a mold clamping force of 650 tons and a maximum injection capacity of 10 kg to which the present invention was applied, the shot cycle was 10 seconds for closing and measuring, 18 seconds for heating and melting, and 1 injection holding pressure. Seconds, cooling 4
Seconds, and the mold opening protrusion was 20 seconds, for a total of 53 seconds. At this time, there was no occurrence of molding defects due to poor weighing.

On the other hand, the conventional mold clamping force of 650 tonnes
When a large automobile part was molded using a thixol molding injection molding machine, a shot cycle of 90 seconds or more was required due to the melting ability of the molding machine. This is mold closing 5
Second, injection, holding pressure 2 seconds, weighing 35 seconds, mold opening 5 seconds, ejection 1 second, middle 42 seconds. This is because the thixomolding method has a low melting ability and requires an intermediate time for melting the raw material chips. At this time, the raw material supply error was ± 2% or more due to instability of the melting behavior, and a weighing defect occurred, and a molding defect such as a filling defect and hot wrinkles occurred.

[0023]

According to the first and second aspects of the present invention, a part for preheating the raw material chips, measuring and transferring the raw material chips, and a part for melting the transferred raw material chips and injecting them into the mold are provided. By separating the material into chips, it is possible to perform measurement while maintaining the tip shape of the raw material chips, so that excessive rotation resistance does not occur when the screw rotates and accurate measurement can be performed. There is no defect, and the molding quality is improved.

Further, since the raw material chips are preliminarily heated and then heated and melted, the melting ability can be improved. Therefore, the raw material chips can be heated to the melting temperature in a short time and the molding time can be shortened. .

Also, large and heavy products which could not be molded without using a long and long injection molding machine can now be molded with a small injection molding machine, and the equipment and molding costs can be reduced. . Furthermore, by separating the preheating and the heating and melting, a high-speed heating means such as an induction heating means can be applied, so that the amount of heat required for melting can be given in a short time with a minimum heating area.

According to the third aspect of the present invention, the preheating means preheats the raw material chips in the measuring cylinder to a temperature at which the chip shape can be maintained. Weighing can be performed accurately. Further, by preheating, there is an effect that the melt injection means can be melted and heated in a short time.

According to the fourth aspect of the present invention, the raw material chips are heated to a temperature at which the raw material chips are brought into a molten state after the raw material supply by the measuring and transferring means is completed by the melting and heating device. It can be carried out.

According to the fifth aspect of the present invention, the injection piston moves the material chips at a low speed to the high-speed heating means after the end of the measurement, and moves at a high speed when the material chips are melted and injected. Therefore, heat melting and injection can be performed efficiently. In the invention according to claim 6,
Since the melting and heating means is a high-speed heating means such as an induction heating device, the material chips can be efficiently heated and melted, and the molding time can be shortened.

According to the seventh aspect of the present invention, since the injection molding apparatus is a vertical injection molding apparatus having an injection cylinder in a vertical direction, it is possible to prevent entrainment of gas due to undulation of molten metal in an injection step. . In the invention according to claim 8, in the case of a metal injection molding apparatus in which the material chips are light alloy chips such as a magnesium alloy, it is necessary to heat the material chips at a high temperature. Failure can be prevented and molding time can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional configuration diagram of a metal injection molding apparatus showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a state of a measuring step in the apparatus of FIG.

FIG. 3 is a configuration diagram showing a state of a heating and melting step in the apparatus of FIG. 1;

FIG. 4 is a configuration diagram showing a state of an injection pressure holding step in the apparatus of FIG. 1;

FIG. 5 is a configuration diagram showing a state of a product removing and measuring step in the apparatus of FIG. 1;

FIG. 6 is a chart illustrating an injection molding process time.

FIG. 7 is a schematic sectional configuration view of a conventional metal injection molding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw material chip 2 Injection molding apparatus 3 Measuring cylinder 4 Measuring screw 5 Preheating means 6 Measuring transfer means 7 Injection cylinder 8 Injection piston 9 High-speed heating means (melting heating means) 10 Melt injection means 11a, 11b Mold 12 Hopper 13 Material supply Mouth 14 Thermocouple 15 Mold cavity

Claims (8)

[Claims] 1. A raw material chip (1) supplied is heated and melted in a cylinder of an injection molding machine to form a mold (11a, 11).
b) In the injection molding method of molding by injection into the inside, the raw material chip (1) is pre-heated, the part to be measured and transferred, and the transferred raw material chip (1) are heated and melted, and the mold ( 11a, 11b). 2. In an injection molding apparatus (2) for heating and melting a supplied raw material chip (1) and injecting it into a mold (11a, 11b) for molding, the raw material chip (1) is formed from one end. A measuring cylinder (3) to be supplied, a measuring screw (4) arranged in the measuring cylinder (3) for measuring and transferring the material chips (1), and a preheating means for preheating the material chips (1) (5), an injection cylinder (7) connected to the other end of the measurement cylinder (3), and an injection cylinder (7) disposed in the injection cylinder (7). An injection piston (8) reciprocating in the inside, and a melt injection means (10) attached to the injection cylinder (7) and comprising a melt heating means (9) for melting and heating the raw material chip (1). Reserve the raw material chips (1) by the transfer means (6) It is heated and supplied to the melt injection means (10).
An injection molding apparatus which heats and melts the raw material chip (1) supplied in (0) and injects it into the molds (11a, 11b). 3. The injection molding apparatus according to claim 2, wherein the preheating means (5) preheats the raw material chips (1) in the measuring cylinder (3) to a temperature at which the chip shape can be maintained. 4. The melting heating means (9) is configured to heat the raw material chips (1) to a temperature at which the raw material chips (1) are in a molten state after the raw material supply by the measuring and transferring means (6) is completed.
The injection molding apparatus according to the above. 5. The injection piston (8) moves the raw material chip (1) at a low speed to the heating and melting section in which the high-speed heating means (9) is disposed after the measurement, and the raw material chip (1) melts. 5. The injection molding apparatus according to claim 2, wherein the injection molding apparatus moves at a high speed when performing injection. 6. The injection molding apparatus according to claim 2, wherein the melting heating means is a high-speed heating means such as an induction heating device. 7. An injection molding apparatus (1) in which an injection cylinder (7) is disposed vertically and a mold (11a, 11b) is disposed above the injection cylinder (7). The injection molding apparatus according to any one of claims 2 to 6, wherein 8. The injection molding apparatus according to claim 2, wherein the material chip (1) is a light alloy chip such as a magnesium alloy.