JPH05277349A - Device for producing powder kneaded material - Google Patents

Abstract

PURPOSE:To provide a device for producing a kneaded material excellent in flowability even in the case of a small quantity of a binder as a material for MIM or CIM and high in density. CONSTITUTION:A kneading device 2 to knead a powder and a binder is provided with a heating means 2b for heating the kneaded material at 110-350 deg.C in a kneading process, a kneading means 2c for kneading the powder and the binder and a pressurizing means 2d for pressurizing the kneaded material to the pressure of 2-9kgf/cm<2> in the kneading process and the kneading device 2 is arranged in a chamber which is 20 to 5X10<-3> Torr in degree of vacuum by being connected to a vacuum evacuating device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a powder kneaded material, and more specifically, the obtained kneaded material has excellent flow characteristics and high density, even though the amount of binder is small. MIM method (Metal Injection Molding Process)
The present invention relates to an apparatus for producing a powder kneaded material suitable for injection molding, which is suitable for use in a CIM method (Ceramics Injection Molding Process).

[0002]

2. Description of the Related Art In the case of applying various kinds of precision parts and functional materials by applying MIM or CIM, which has recently attracted attention, fine powders of metals, alloys, and ceramics and an organic binder in a predetermined ratio. The mixture is kneaded to obtain a kneaded product having desired flow characteristics, and the kneaded product is subjected to injection molding or extrusion molding to obtain a molded product having a desired shape. Then, the molded body is subsequently heated to remove the binder, and then sintered under a predetermined condition, and the obtained sintered product is subjected to finish processing.

In the above-mentioned MIM and CIM, it is said that the smaller the amount of the organic binder used, the more preferable. This is because, when the binder is removed from the kneaded product, if the amount of binder increases, fatal structural defects such as blisters and cracks and large dimensional changes easily occur in the molded product after the process. Is. However, if the amount of the binder is too small, the uniform kneading with the powder does not proceed smoothly, and the flow characteristics of the obtained powder kneaded material deteriorate, making it difficult to obtain a good molded product during injection molding or extrusion molding. .. Therefore, in MIM and CIM, the mixing ratio of the powder and the organic binder to be used is determined in consideration of the above problems.

By the way, in both MIM and CIM, the kneading of the powder and the organic binder is usually carried out under atmospheric pressure under heating / pressurization. However,
The kneading in the air has an adverse effect on the uniform kneading of the powder and the organic binder due to the adsorption of moisture, humidity, and air in the air on the surface of the powder. This causes a problem that the properties of the kneaded body are remarkably different. In particular, the powder is, for example, Ti powder with high surface activity, or the finer the powder,
The above-mentioned problems are prominent.

From the above, kneading is performed at 20 to 50 To
It has also been attempted to carry out under a vacuum as low as rr. However, the conventional kneading under vacuum is usually about 2 kgf /
Since it is carried out under a low pressure of about cm ^2, it is not affected by moisture or climatic conditions, but there is a problem in that the effect of dispersing the powder is extremely deteriorated and the formability is lowered. The tendency becomes more remarkable as the powder becomes finer.

In order to solve such a problem, it is necessary to increase the amount of the organic binder compounded. However, on the other hand, it takes a long time to remove the binder from the molded body, and the shape retention is poor. As a result, the productivity is likely to be lowered, and further, the quality of the sintered product is lowered and the quality of the product is also lowered. An object of the present invention is to solve the above problems in MIM and CIM, and to provide an apparatus for producing a powder kneaded product having excellent flow characteristics despite a small amount of organic binder.

[0007]

In order to achieve the above-mentioned object, in the present invention, a kneading device for kneading powder and a binder comprises a heating means for heating the kneaded product to 110 to 350 ° C. in the kneading process. A kneading means for kneading the powder and the binder, and a pressurizing means for pressurizing the kneaded material at a pressure of ² to 9 kgf / cm ^{2 in} the kneading process, and the kneading device is connected to a vacuum exhaust device. Provided is an apparatus for producing a powder kneaded material, which is arranged in a chamber having a vacuum degree of 20 Torr to 5 × 10 ⁻³ Torr.

[0008]

In the apparatus of the present invention, the kneading of the powder and the binder is evacuated to a vacuum degree of 20 Torr to 5 × 10 ^-3 Torr.
The kneading device is placed in a high vacuum chamber. Therefore, during kneading, the kneaded product is hardly affected by moisture and humidity.

Further, since the kneading is carried out under heating and pressurization at a temperature of 110 to 350 ° C. and a pressure of ^{2 to} 9 kgf / cm ² , the effect of dispersing the powder is improved and uniform kneading is possible even with a small amount of binder. Then, it becomes possible to obtain a powder kneaded product having excellent flow characteristics.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An example of the apparatus of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of the device of the present invention, and FIG. 2 is a schematic sectional view of the kneading device. In FIG. 1, a kneading device 2 described later is arranged in a chamber 1 having a seal structure. And chamber 1
A vacuum evacuation device 3 in which a rotary pump 3a and a mechanical booster 4 are combined is connected to the via a path p ₁ . Further, an inert gas introduction device 4 such as N ₂ gas or Ar gas is connected to the chamber 1 via a path p ₂ .

As shown in FIG. 2, the kneading device 2 encloses a kneading container 2a having an upper opening for kneading a kneading material 5 composed of powder and a binder, and an outer wall of the kneading container 2a. And heating means 2b for heating the kneaded material 5,
It is indispensable that the kneading material 5 is composed of kneading means 2c for kneading the kneading material 5 and pressurizing means 2d for continuously pressing the kneading material 5 in the kneading process of the kneading material 5.

First, the heating means 2b may be any means as long as it can heat the kneaded material 5 to a temperature of 110 to 350 ° C., for example, an electric heater or a pipe for flowing a heat medium such as hot oil. Can be raised. As the kneading means 2c, 2c, any means may be used as long as it can overcome the viscosity of the kneaded material 5 and knead it.

The kneading means 2c, 2c are rotary shafts 6a which are hermetically inserted into the chamber 1 from the power source 6 shown in FIG.
It is adapted to be driven by operating the power source 6 in connection with the power source 6. Next, the pressurizing means 2d has a lid shape for pressurizing the entire kneaded material 5 from the opening of the kneading container 2a, and the shaft 7a provided at the center thereof has the hydraulic or pneumatic cylinder shown in FIG. It is connected to the device 7. The cylinder device 7 is connected to the power source 6 and driven by the power source 6. As a result, the shaft 7a moves up and down as shown by the arrow, and the kneaded material 5 can be pressed by the lower surface of the heating means 2d at a pressure of ² to 9 kgf / cm ² .

When the pressure at this time is less than 2 kgf / cm ² , the uniform kneading of the powder and the binder does not proceed sufficiently, the flow characteristics of the resulting kneaded product deteriorate, and when the pressure is more than 9 kgf / cm ^2. Is considered to be advantageous for improving the properties of the kneaded product, but more than that, the cylinder device 7 is unnecessarily increased in size, which is not industrially advantageous.

In the initial stage of the kneading process, the powder is not yet compatible with the binder, and therefore often scatters from the kneading container 2a. To prevent such problems,
For example, as shown in FIG. 2, the sealing lid 8 is attached to the upper part of the kneading container 2a via the seal 8a, and the shaft 7a of the pressurizing means 2d is rotatably sealed and pulled out from the center portion by the seal 8b. Is preferred.

The device of the present invention operates as follows. First, a predetermined powder and a binder are put into the kneading container 2a at a predetermined quantitative ratio. Any powder or binder may be used as long as it can be used in MIM or CIM and is not particularly limited. Next is chamber 1
And close the leak valve 9a of the leak pipe 9,
The vacuum exhaust device 3 is activated to move the inside of the chamber 1 to 20 Torr to 5
A vacuum of 10 ^-3 Torr is applied.

When the degree of vacuum is lower than 20 Torr, water and moisture in the chamber 1 cannot be sufficiently removed, so that the flow characteristics of the obtained kneaded product are apt to deteriorate, and 5 × 10 ⁻³ To
Above rr, the effect practically only reaches saturation. When kneading surface-active powder such as Ti powder, for example, a desired inert gas is introduced into the chamber 1 from the inert gas introducing device 4 of FIG. You may adjust to a proper atmosphere.

While maintaining the degree of vacuum, the heating means 2
b, the power source 6 is operated to rotate the driving means 2c, 2c, and at the same time, the cylinder device 7 is operated to lower the pressurizing means 2d to lower the pressure on the kneaded material 5 from ² to 9 kgf / cm ² . Is applied. After the pressurizing / heating kneading under vacuum is continued for a predetermined time, the operation of the pressurizing means 2b and the kneading means 2c, 2c is stopped to raise the pressurizing means 2d, and when the kneaded material 5 is cooled, vacuum exhaust is performed. The operation of the device 3 is stopped, the leak valve 9b is opened, the pressure in the chamber 1 is set to normal pressure, and the kneaded product is taken out.

Using this apparatus, the powders and binders shown in Table 1 were mixed in the indicated proportions (% by weight) and kneaded under the indicated conditions. The density of the obtained kneaded product was measured by the Archimedes method, and the relative density (%) to the calculated vacuum degree was calculated. The above results are collectively shown in Table 1.

[0020]

[Table 1] Further, the relationship between the flow characteristics of each kneaded product and the temperature was measured.
The relationship is shown in FIG. 3 for Samples A ₁ and A ₂ , FIG. 4 for Samples B ₁ and B ₂ , FIG. 5 for Samples C ₁ , C ₂ and C ₃ , and to Samples D ₁ , D ₂ and D ₃ . Is shown in FIG. 6, Samples E ₁ and E ₂ are shown in FIG. 7, and Samples F ₁ and F ₂ are shown in FIG. In all of the figures, the mark ◯ indicates the case where the conditions were satisfied according to the present invention, and the mark  indicates the case when the conditions were the atmosphere.

As is clear from the results in Table 1 and FIGS. 3 to 8, the kneaded product produced under the conditions using the apparatus of the present invention has a smaller amount of binder than that produced in the atmosphere. In addition, it has a high density and excellent flow characteristics.
The same effect can be obtained even if the powder is a mixed powder of metal and ceramics.

[0022]

As is apparent from the above description, by using the device of the present invention, it is possible to achieve high density with a small amount of binder.
It is possible to produce a kneaded product having high fluidity. Therefore, it can be applied to MIM and CIM to stably produce a sintered product of excellent quality, and its industrial value is very large.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a device of the present invention.

FIG. 2 is a schematic sectional view showing an example of a kneading device of the present invention.

FIG. 3 is a graph showing the relationship between the flow characteristics of samples A ₁ and A ₂ and temperature.

FIG. 4 is a graph showing the relationship between the flow characteristics of samples B ₁ and B ₂ and temperature.

FIG. 5 is a graph showing the relationship between the flow characteristics of samples C ₁ , C ₂ and C ₃ and temperature.

FIG. 6 is a graph showing the relationship between the flow characteristics of samples D ₁ , D ₂ and D ₃ and temperature.

FIG. 7 is a graph showing the relationship between the flow characteristics of samples E ₁ and E ₂ and temperature.

FIG. 8 is a graph showing the relationship between the flow characteristics of samples F ₁ and F ₂ and temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 chamber 2 kneading device 2a kneading container of kneading device 2 b heating means of kneading device 2 c kneading means of kneading device 2 d pressurizing means of kneading device 2 evacuation device 3a rotary pump 3b mechanical booster 4 inert gas introducing device 5 Kneaded material 6 Power source 6a Rotating shaft 7 Cylinder device 7a Shaft 8a, 8b Seal 9 Leak pipe 9a Leak valve

Claims (2)

[Claims] 1. A kneading device for kneading powder and a binder,
A heating means for heating the kneaded product to 110 to 350 ° C. in the kneading process, a kneading device for kneading the powder and the binder, and a pressurizing device for pressurizing the kneaded product at a pressure of ² to 9 kgf / cm ^{2 in} the kneading process. A powder kneaded product, characterized in that the kneading device is provided in a chamber connected to a vacuum exhaust device and having a vacuum degree of 20 Torr to 5 × 10 ⁻³ Torr. apparatus. 2. The apparatus for producing a powder kneaded material according to claim 1, further comprising an inert gas introducing device connected to the chamber.