JPH06234054A - Metallic injection molded articles and their production - Google Patents

Abstract

PURPOSE:To provide the process for production of metallic injection molded articles capable of safely and inexpensively producing the metallic injection molded articles which can be easily recycled, have high mechanical strength and have high dimensional and weight accuracy under a good working environment. CONSTITUTION:Metallic raw materials K which have >=450 deg.C m. p. and have the shape of debris of machining are supplied to an inline screw type injection machine 1 having 1.1 to 2.0 compression ratio. The supplied metallic raw materials K are kneaded by driving the screw 10 and are kneaded and melted by the heat obtd. by the kneading and the heat applied from the outside of a cylinder barrel 2. A prescribed amt. of the raw materials are stored into the cylinder barrel 2. The heat applied from the outside of the cylinder barrel 2 is controlled within + or -15 deg.C of the m.p. of the metallic raw materials K at the time of obtaining the metallic injection molded articles by injecting the stored metallic raw materials K into metallic molds 40. The metallic raw materials are injected together with the metallic raw materials K solidified in the front end of a nozzle 3 into the metallic molds 40 at the time the injection stroke of the previous cycle is executed in an injection stroke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal injection molded product and a method for producing the same, and specifically, a metal raw material having a melting point of 450 ° C. or less is directly kneaded and melted by an in-line screw type injection machine and injected into a mold. The present invention relates to a metal injection-molded product obtained by the above and a method for producing the metal injection-molded product.

[0002]

2. Description of the Prior Art Mechanical components, as is well known, are made of metal or synthetic resin. When molding machine components from synthetic resins, most are by injection molding. The injection molding method is suitable for high-mix, high-volume production of precision molded products. Therefore, automobile parts, OA equipment parts, FA equipment parts, office equipment parts and the like can be obtained by this injection molding method. However, since there are many types of resin and there are a wide variety of molded products, it is important to separate the resins by type even if they collect unnecessary synthetic resin molded products, even if they use chemical operations. It is extremely difficult even by the enemy method, and it is not possible economically. Molding with a mixture of different types of resin does not give a molded product of the desired quality.Therefore, the collected synthetic resin is used only for molding paving stones, benches, etc. where relatively strict quality is not required. Limited and not fully recycled.

On the other hand, the above-mentioned mechanical components made of metal are manufactured by machining such as cutting and pressing, and also by a sintering method, a casting method and the like obtained from metal powder. The casting method is a method of obtaining a product by injecting molten metal into sand or a mold having voids having the shape and dimensions of the product to be manufactured, and simply by casting the molten metal into the mold, There is an advantage that a desired casting or product can be manufactured. Further, it is relatively easy to collect a used casting product, melt it in a melting furnace, and reuse it. However, according to the casting method, since the molten metal is solidified under the action of gravity, there is a drawback in that the cast product has cavities and the quality is poor. In addition, since it is solidified under the action of gravity, it is impossible to make a delicate casting product. Therefore, in order to improve quality, manufacture more complicated and elaborate castings, or rationalize production, a pressure casting method using a force other than gravity has been proposed. As the pressure casting method, hot chabber method, cold chabber method, squeeze cast method, etc. are known.By the squeeze cast method, large products such as aluminum wheels of automobiles are cast, and small and medium-sized articles are
It is manufactured by the hot chabber method, cold chabber method, and the like.

[0004]

According to the above pressure casting method, it is possible to remove cavities from the casting to some extent.
The quality is improved to some extent. Further, since the pressure is applied, metal products of various shapes can be obtained relatively accurately. Further, the casting product produced by the pressure casting method can be remelted in the melting furnace if it is collected, and thus can be reused relatively easily.
However, since the entire mold is put in a container and the atmosphere is increased by gas pressure for casting, the atmospheric pressure is generally low. Therefore, air bubbles are often left in the casting, a product having sufficient mechanical strength cannot be obtained, and the dimensional and weight accuracy is not sufficient, so that it is impossible to perform precision molding. Further, like the general casting production, there is a drawback that a large amount of heat is released from a melting furnace for melting a metal and a large amount of energy is required. Further, the pressure casting method also has a drawback that the working environment is bad like the conventional casting method. That is, since the metal must be melted in the melting furnace, it is a high temperature operation. There is also a risk of burns from the molten metal scattered from the melting furnace. Furthermore, since there is a melting furnace, the equipment becomes large or the factory becomes large.

Therefore, the present invention provides a metal injection-molded article which is easy to recycle, has high mechanical strength, and has high dimensional and weight accuracy, and high mechanical strength.
It is an object of the present invention to provide a method for producing a metal injection-molded article, which is capable of producing a metal injection-molded article having a high dimensional and weight accuracy in a good working environment, safely and at low cost.

[0006]

In order to achieve the above object, the present invention provides a metal injection molded product according to claim 1, which has a melting point of 450 ° C. or less, a particle diameter of 5 mm and a length of 5 mm. 1
A granular or columnar metal raw material having a size of 0 mm or less or a metal raw material having a shape of cutting powder of 10 mm or less and having a size of 10 mm or less is directly kneaded and melted by an in-line screw type injection machine 1 and injected into a mold. can get. In the invention described in claim 2, the metal raw material according to claim 1 is zinc, tin,
Lead, bismuth, terbium, tellurium, cadmium, thallium, astatine, polonium, selenium, lithium, indium, iodine, sulfur, sodium, potassium, phosphorus, rubidium, cesium, francium, gallium metal element or alloy element alone or metal element or It is obtained from one kind or a mixture of two or more kinds of alloying elements. The invention according to claim 3 has a supply step of supplying the metal raw material according to claim 1 or 2 to the in-line screw type injection machine 1 having a melting point of 450 ° C. or less, and the metal raw material supplied by the supply step. A kneading and melting step of driving and kneading 10 and kneading and melting by the heat obtained by the kneading and the heat applied from the outside of the cylinder barrel 2, and the metal raw material kneaded and melted in the kneading and melting step in the injection cylinder barrel 2. When a metal injection-molded article is obtained by a storage step of storing a predetermined amount of the metal raw material and an injection step of injecting the metal raw material stored by the storage step into the mold 40, heat applied from the outside of the cylinder barrel 2 is applied to the melting point of the metal raw material. Plus / minus 1
In addition to controlling within 5 degrees C, the injection stroke is configured to inject into the mold 40 together with the metal raw material solidified at the tip of the nozzle 3 when the injection stroke of the previous cycle is performed. The invention according to claim 4 is the kneading and melting process according to claim 3, wherein a screw having a compression ratio of 1.1 to 2.0 is used.

The metal raw material in the present invention refers to a metal element or alloy element alone or a mixture of one or more metal elements or alloy elements. Practical examples include zinc, tin, lead, bismuth, terbium, tellurium,
Examples thereof include cadmium, thallium, astatine, polonium, selenium, lithium, indium, iodine, sulfur, sodium, potassium, phosphorus, rubidium, cesium, francium and gallium. Each of these metal raw materials has a melting point of 450 ° C. or less, and is a metal element or alloy that can be kneaded and melted by an in-line screw type injection machine and injection-molded.

These metal raw materials can be obtained by various methods. For example, the ingot can be obtained by chipping with a chipping machine. Alternatively, cutting powder obtained by cutting with a cutting machine can be used. The metal raw materials obtained by these methods are relatively thin and long. Since it is long, it melts easily from the tip in the cylinder barrel 2. Furthermore, conventionally known reduction method, gas atomization method,
It can also be obtained by a vacuum spraying method, a rotating consumable electrode method, or the like.

The particle size or size of the raw material metal applied to the present invention is not particularly limited as long as it can be supplied to the cylinder barrel and kneaded and melted. However, considering the ease of kneading / melting in the cylinder barrel and the cost of obtaining the metal raw material, the size of the metal raw material is 10 mm or less, preferably 5 mm or less in any case. That is, when the metal raw material is granular or columnar, the particle size is 5 mm and the length is 10 mm or less, and when it is in the shape of cutting powder for machining, the length is preferably 10 mm or less.

The metal raw material selected as described above is
It is injected into the mold device from an in-line screw type injection machine, and a screw including a supply unit, a compression unit, a measuring unit, etc. is applied to the screw. The compression ratio of the screw, that is, the ratio of the space capacity in the groove of the supply section to the space capacity of the groove in the metering section is selected to be 1.1 to 2.0. A screw having a compression ratio of 1, that is, a screw that is not compressed can melt the above-mentioned metal, but the melting efficiency becomes poor. On the other hand, when the compression ratio exceeds 2, the torque for crushing the metal raw material becomes too large, and the resistance for advancing the metal raw material forward becomes too large, resulting in a "closed" state. As a result of the experiment, the preferable compression ratio was 1.2 to 1.8.

A heating device is provided on the outer peripheral portion of the cylinder barrel of the in-line screw type injection machine, and the temperature of the heating device is precisely and precisely controlled. That is, the melting point of the target metal raw material is controlled within ± 15 ° C, preferably within ± 10 ° C. If the temperature is lower than this temperature, the rotational torque of the screw increases, the motor, the drive mechanism, etc. are upsized and the cost is increased. On the other hand, if the temperature exceeds the above range, melting will occur too quickly. As a result, the molten metal raw material and the unmelted metal raw material are no longer pumped from the supply section to the next compression section. Metal raw materials have higher thermal conductivity than plastics, and rapidly cool and solidify even in the mold. Therefore, it is desirable that the injection speed is also higher than that at the time of injection molding of plastic, that is, 20 cm / s or more.

Next, an embodiment of the injection molding machine will be described. As shown in FIG. 1, the injection molding machine S includes an inline screw type injection machine 1 and a mold device 40. The injection machine 1 includes a cylinder barrel 2, a screw 10 that is rotationally driven in the cylinder barrel 2 and is also axially driven, and a drive device 20 that drives the screw 10.
And a supply device 30 for supplying the metal raw material to the cylinder barrel 2.

The cylinder barrel 2 has a tubular shape. A nozzle 3 for injecting the molten metal raw material is provided at the tip portion thereof, and the end portion on the opposite side of the nozzle 3 is connected to the casing 21 of the drive device 20. And cylinder barrel 2
An opening 4 for supplying the metal raw material is opened at a position closer to the drive device 20 than the intermediate portion. On the outer peripheral portion of the cylinder barrel 2, heating devices 5, 5, ... Are provided from the opening 4 to the nozzle 3. Although not shown in the figure, the heating devices 5, 5, ... Are capable of finely controlling the temperature by a control device.

The screw 10 is made of a metal raw material as shown in FIG.
The supply part 12 which bites into 1 and 11 and sends it to the next compression part 13 and the compression part 13 which makes the molten metal compressed by the screw grooves 11 and 11 becoming gradually shallower and causing the entrained air to flow back to the opening 4 side. , Measuring unit 1 for storing molten metal
4 and a backflow prevention ring 16 is provided at the tip thereof. The compression ratio, that is, the ratio of the space capacity V2 in the groove of the supply unit 12 and the space capacity V1 in the groove of the measuring unit 14 is 1.
It is selected as 1 to 2.0.

The drive unit 20 includes an electric motor or a hydraulic motor 22. A reduction gear is housed in the casing 21, and the screw 10 is rotationally driven at a predetermined speed via the reduction gear. An injection ram is provided inside the casing 21, and the screw 10 is axially driven at a relatively high speed. The drive speed of the motor and ram is also controlled by the controller. The supply device 30 includes a funnel-shaped hopper 31.
And a screw feeder 33 provided below the hopper 31 and a supply path 34. The screw of the screw feeder 33 is driven at a speed controlled by the controller. The lower end of the supply passage 34 is connected to the opening 4 of the cylinder barrel 2.

The mold device 40 includes a fixed plate 41 and a movable plate 4.
2 and. A fixed mold 43 and a movable mold 44 are attached to the boards 41 and 42, respectively. A sprue 45 is formed in the fixed mold 43 in the axial direction, and a runner 46 is formed along the parting line between the fixed mold 43 and the movable mold 44. Movable mold 4
4 is provided with a cavity 47 for molding a product. The movable platen 42 is driven with respect to the fixed platen 41 in the mold opening direction or the mold closing direction, but a drive mechanism is not shown. Further, the fixed plate 41 and the movable plate 42 are connected by tie bars 48, 48, ... And the movable mold 44 is clamped to the fixed mold 43 by a toggle mechanism, but the toggle mechanism is not shown.

Next, an example of manufacturing a metal product using the above injection molding machine will be described. A metal raw material K having a size of 10 mm or less is prepared and stored in the hopper 31. On the other hand, the heating device 5,
The temperature of 5, ... Is set within ± 15 degrees C of the melting point of the metal raw material K by the control device. The motor 22 is started to drive the screw 10, and at the same time, the screw feeder 33 is driven at a predetermined speed. Then, the metal raw material K stored in the hopper 31 is supplied to the supply unit 12 in the cylinder barrel 2 through the opening 4 from the predetermined amount-specified supply passage 34 determined by the rotation speed of the screw feeder 33. The supplied metal raw material K is kneaded by the rotating screw 10. While being kneaded, it is melted by frictional heat and heat applied from the heating devices 5, 5, ... And is sent to the next compression section 13. Compressor 1
Since the screw grooves 11 of 3 are gradually shallower, the molten metal is compressed and the entrained air flows back to the opening 4 side. Then, the melt-kneaded metal is measured by the measuring unit 1.
Sent to 4. As the screw 10 moves backward,
Stored in a predetermined amount.

The mold device 40 is closed and the nozzle 3 provided at the tip of the cylinder barrel 2 is sprued 45.
Touch. Then screw 10 with the injection ram.
Is driven to inject the stored molten metal into the cavity 47. Since the solidification of the molten metal is fast,
The speed of the injection ram is controlled so that the speed of injection is not less than cm / s. After cooling and solidification, the mold is opened and the metal injection molded product is taken out. During this, kneading, melting, compression and storage for the next injection are performed as described above. And it ejects similarly. At this time, the metal solidified at the tip of the nozzle 3 by the previous injection is simultaneously injected. Less than,
By repeating the above operation, the metal raw material as described above is used for metal injection molding, for example, automobile parts, OA equipment parts, FA equipment parts, office equipment parts, home appliance parts, electric tool parts, Obtain parts for communication equipment.

[0019]

【Example】

Example 1: [Preparation of metal raw material] The metal raw material was obtained by cutting an ingot of a lead alloy of two elements of lead-tin. The particle size distribution and maximum size of the obtained metal raw material were measured. The results are shown in Table 1. Table 1 Particle size distribution (Wt%) Size (length mm) Ratio 5 or less 72.0 5-10 15.0 10-15 10.5 15 or more 2.5 The maximum length was 18 mm. [Injection molding] The above-mentioned metal raw material is injected into a mold by the inline screw type injection machine having the compression ratio of 1.5 described above.
The terminal of the battery for the wheel car was obtained. At this time, since the melting point of the lead alloy is 329 ° C., the temperature of the heating devices 5, 5, ... Of the cylinder barrel 2 is set to 3 in consideration of frictional heat with the screw.
It was set to 25 degrees C. The temperature of the heating device 5 of the nozzle 3 was set to 330 ° C, which is higher than this. Injection speed is 30 cm
Was / s.

[Results] The dimensional accuracy and weight accuracy of the terminals of the motorcycle battery molded under the above conditions were measured. Although the cavity of the mold had an acute angle part, it was also injected into the acute angle part, and the dimensional accuracy and weight accuracy were good.

Concrete Example: A concrete molding method of the core used in the lost core molding method of the bismuth-tin alloy will be described.
Since the melting point of this bismuth-tin alloy is 90 ° C, the temperature of the heating devices 5, 5, ... Of the cylinder barrel 2 is set to 85 ° C in consideration of frictional heat with the screw. Since the melting point of bismuth-tin alloy is low, the temperature of the heating device 5 of the nozzle 3 is also set to 85 ° C. Injection speed is 2 from other experimental examples
Set to 0 cm / s. Then, by injecting into the mold by the in-line screw type injection machine, a core molded product excellent in size and weight accuracy can be obtained. The obtained core molded product is inserted into a plastic mold to obtain a glass-filled nylon plastic molded product having a shape that encloses the core. Thereafter, the plastic molded product is heated to a temperature of 90 to 100 ° C. higher than the melting point of the bismuth-tin alloy. Then, since the core is formed of the bismuth-tin alloy, it melts. And it melts out from the hole provided in the plastic molded product. In this way, a seamless molded article of hollow glass-filled nylon is obtained. An example of molding a terminal of a battery for a motorcycle from a lead-tin binary alloy and a concrete molding method of a core used in a lost core molding method of a bismuth-tin alloy have been described. It is obvious that the above-mentioned automobile parts, OA equipment parts and the like can be obtained in the same manner from other metal raw materials having a temperature of C or less.

[0022]

As described above, the metal injection-molded article according to the present invention is a granular or columnar metal raw material having a melting point of 450 ° C. or less, a particle size of 5 mm and a length of 10 mm or less, or a machining cutting powder. It is obtained by directly kneading and melting a metal raw material having a shape of 10 mm or less and using an in-line screw type injection machine and then injecting it into a mold, so that it is excellent in size and weight accuracy and has a large mechanical strength. . Further, since the molded product is molded from metal, it can be easily recycled. According to the invention of claim 3, a metal raw material having a melting point of 450 ° C. or less is injected into a mold by an in-line screw type injection machine to obtain a metal injection molded product.
It does not require a melting furnace, which is a high-temperature work and has a large amount of heat radiation.
Therefore, it is possible to obtain a metal injection-molded product without fear of burns and with little energy loss, that is, excellent in working environment, safe and at low cost. Further, since a metal injection molded product is obtained by injection into a mold, it is possible to obtain a metal injection molded product having excellent dimensional and weight accuracy and high mechanical strength. In particular, since the heat applied from the outside of the cylinder barrel 2 is controlled to be within ± 15 ° C. of the melting point of the metal raw material, the metal raw material is efficiently melt-kneaded, stored and injected. In the injection process, when the injection process of the previous cycle is carried out, it is injected into the mold together with the metal raw material solidified at the tip of the nozzle 3, so it is not necessary to remove the solidified metal, and the injection cycle can be shortened. According to the invention of claim 4, since the screw having a compression ratio of 1.1 to 2.0 is used, in addition to the effect of the invention of claim 3, a metal raw material having a melting point of 450 ° C. or less is used. With the in-line screw, it is possible to effectively melt and obtain the effect of advancing.

[Brief description of drawings]

FIG. 1 is a view showing an example of an injection molding machine used for carrying out the present invention, in which (a) is a front view showing a part in section, (b)
[Fig. 3] is a partially enlarged view of a screw portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 In-line screw type injection machine 2 Cylinder barrel 3 Nozzle 5 Heating device 10 Screw 11 Screw groove 12 Supply part 13 Compressing part 14 Measuring part 40 Mold device

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[Procedure amendment]

[Submission date] March 25, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Prior Art Mechanical components, as is well known, are made of metal or synthetic resin. When molding machine components from synthetic resins, most are by injection molding. The injection molding method is suitable for high-mix, high-volume production of precision molded products. Therefore, automobile parts, OA equipment parts, FA equipment parts, office equipment parts and the like can be obtained by this injection molding method. However, the kind of the resin Many since moldings are also diverse, even if recovered becomes unnecessary synthetic resin molded article, separating the resin for each type can be used chemical operations, also physically It is extremely difficult to do so economically, and it is not economically feasible. Molding with a mixture of different types of resin does not give a molded product of the desired quality.Therefore, the collected synthetic resin is used only for molding paving stones, benches, etc. where relatively strict quality is not required. Limited and not fully recycled.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

On the other hand, the above-mentioned mechanical components made of metal are manufactured by machining such as cutting and pressing, and also by a sintering method, a casting method and the like obtained from metal powder. The casting method is a method of obtaining a product by injecting molten metal into sand or a mold having voids having the shape and dimensions of the product to be manufactured, and simply by casting the molten metal into the mold, There is an advantage that a desired casting or product can be manufactured. Further, it is relatively easy to collect a used casting product, melt it in a melting furnace, and reuse it. However, according to the casting method, since the molten metal is solidified under the action of gravity, there is a drawback in that the cast product has cavities and the quality is poor. In addition, since it is solidified under the action of gravity, it is impossible to make a delicate casting product. Therefore, in order to improve quality, manufacture more complicated and elaborate castings, or rationalize production, a pressure casting method using a force other than gravity has been proposed. The pressure casting method hot tea
Members method, cold chamber method, squeeze casting method and the like are known, by the squeeze casting method, large products, such as aluminum wheel of a motor vehicle is cast, small and medium-sized of small products, hot-chamber method, is produced in a cold chamber method or the like ing.

Claims (4)

[Claims] 1. A melting point of 450 ° C. or less and a particle size of 5 m.
m or a grain-like or columnar metal raw material K having a length of 10 mm or less or a machined cutting powder or the like and having a size of 10
A metal injection-molded product obtained by directly kneading and melting a metal raw material K having a size of mm or less with an in-line screw type injection machine 1 and injecting it into a mold 40. 2. The metal raw material K according to claim 1 is zinc,
Tin, lead, bismuth, terbium, tellurium, cadmium,
Thallium, astatine, polonium, selenium, lithium, indium, iodine, sulfur, sodium, potassium, phosphorus, rubidium, cesium, francium, gallium metal element or alloying element alone or one or more metal element or alloying element Metal injection moldings obtained from the mixture. 3. A supply step of supplying the metal raw material K according to claim 1 or 2 having a melting point of 450 ° C. or less to the in-line screw type injection machine 1, and the metal raw material supplied by the supply step in the screw 10. A kneading and melting step of driving and kneading and kneading and melting by the heat obtained by the kneading and the heat applied from the outside of the cylinder barrel 2, and the metal raw material K kneaded and melted in the kneading and melting step into the injection cylinder barrel 2. When a metal injection molded product is obtained by a storage process of storing a predetermined amount and an injection process of injecting the metal raw material K stored by the storage process into the mold 40, heat applied from the outside of the cylinder barrel 2 is applied to the metal raw material K. The melting point is controlled within plus / minus 15 ° C, and in the injection stroke, the metal raw material K solidified at the tip of the nozzle 3 when the injection stroke of the previous cycle is performed. Both mold 40
A method for producing a metal injection-molded product, which comprises: 4. The method for producing a metal injection molded product according to claim 3, wherein a screw having a compression ratio of 1.1 to 2.0 is used.