JPH0866759A - Spray deposition method - Google Patents

Abstract

PURPOSE: To reduce the thickness of a hole layer by turning an atomizer to move the jet flow of a high-pressure gas back and forth between the central part and outer peripheral part of a preform and stopping the forward and backward movement for a specific period in the inner and outer peripheral parts in one period of the forward and backward movement. CONSTITUTION: The jet flow 6 of the high-pressure gas ejected by the atomizer 5 is blown to molten metal 2 flowing down perpendicularly to atomize this molten metal. The atomized metallic particles are deposited on a moving base plate 9, by which the preform 11 is obtd. The atomizer 5 is rotated to move the jet flow of the high-pressure gas back and forth between the central part and outer peripheral part of the perform 11 and is stopped for the 1/18 to 1/3 period in the inner and outer peripheral parts in one period of the forward and backward movement. As a result, the shape control of the upper surface of the preform 11 is executed and the thickness of the hole layer in the outer peripheral part or the outer edge part is reduced, by which the yield of the defectless part of the castable preform is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spray deposition method known as an Osprey method or a spray casting method, and more particularly to a spray deposition method for reducing the pore layer of a cylindrical preform. Is.

[0002]

2. Description of the Related Art The spray deposition method can obtain a uniform fine structure and can simplify the molding process as compared with the conventional powder metallurgy method. Therefore, it has attracted attention as a method which can be expected to greatly improve the productivity. There is. An example of this spray deposition method is:
JP-B-54-29985, JP-A-62-156206 and the like can be mentioned.

FIG. 5 is an explanatory view showing an example of an apparatus for producing a block preform by using the spray deposition method. A metal melt 2 is put in the tundish 1, and the metal melt 2 is allowed to flow down naturally in a chamber 4 in a non-oxidizing atmosphere via a tundish nozzle 3. A gas atomizer 5 is arranged below the tundish 1,
The high-pressure inert gas ejected from the gas atomizer 5 becomes a jet stream 6 and is sprayed on the molten metal stream 7.
This is atomized. The atomized metal particles are deposited in a semi-solidified state on the substrate 9 set on the lower collector 8 and gradually solidified. The collector 8 is a stepping motor
It can be moved up and down and rotated using 10 etc. as a drive source, and if the collector 8 is gradually lowered according to the amount of metal particles deposited, the distance between the tundish nozzle 3 and the topmost surface of the deposition is kept constant. Thus, it is possible to obtain a lump-shaped preform 11 having an increased deposition height.

The material produced by the above spray deposition method is
Less segregation than materials made by ingot method,
It has the features that there is little contamination of unnecessary elements (oxygen etc.) and that the type and amount of alloying elements can be increased because the solid solution limit of solute elements is expanded due to rapid solidification.

[0005]

On the other hand, the present inventors have
Up to now, the above-mentioned spray deposition method has been improved so that the gas atomizer 5 is rotated by employing, for example, the cam mechanism shown in FIG. 6 shown in FIG. 1 of JP-A-62-156206, and ejected from the gas atomizer 5. The high pressure inert gas jet stream 6 is reciprocated between the central portion and the outer peripheral portion of the preform 11,
Attempts have been made to produce a cylindrical preform having the above characteristics.

However, in the cylindrical preform obtained by the above method, spherical particles adhere to the outer peripheral surface of the preform cooled by spray gas, radiation, etc. during production, and the three points of particles are vacant. It has a hole layer with a thickness of about 10 mm that becomes holes. The presence of this vacancy layer causes cracking during processing such as forging in a later step, and therefore must be removed by turning, which causes a reduction in yield. Therefore, there has been a problem to reduce the void layer and improve the sound yield of the preform, which is a value obtained by dividing the weight of the preform from which the outer peripheral void layer is removed by the melt weight.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the thickness of the pore layer of the preform so that the yield of sound parts that can be forged is improved. It is intended to provide an improved spray deposition method.

[0008]

In order to achieve the above object, in the spray deposition method according to the present invention, a jet stream of high-pressure gas ejected from an atomizer is sprayed onto a vertically molten metal melt to atomize it. In the spray deposition method in which the atomized metal particles are deposited on a moving substrate to obtain a preform, the atomizer is rotated to generate a jet stream of high-pressure gas between the central portion and the outer peripheral portion of the preform. Reciprocating between 1 and 18-1 /
It stops for three cycles.

[0009]

In order to reduce the thickness of the outer peripheral hole layer, the inventors of the present invention have studied the above-mentioned problems and found various solutions to the problems.
It was thought that a method of increasing the amount of heat flowing into the deposition surface per unit time should be taken. And as a concrete method,
A method of reducing the atomizing gas pressure to increase the generated particle size and increasing the heat amount of the spray cone itself,
Consider a method to reduce the collector rotation and descent speed to increase the amount of deposition per unit time, a method to change the movement pattern and locally increase the amount of heat only at the places where the preform is cooled by the atomizing gas, etc. It was However, the method of increasing the amount of heat of the spray cone itself and the method of rotating and lowering the collector may cause a problem that the temperature of the entire preform increases and the desired degree of quenching cannot be obtained, resulting in deterioration of mechanical properties. On the other hand, in the method of changing the movement pattern, the degree of quenching is obtained even with the current movement pattern. Therefore, the characteristic of the rapid solidification is changed by changing the movement pattern that can increase the amount of heat of only the outer peripheral surface of the preform. It is considered that the thickness of the outer peripheral hole layer can be reduced while satisfying the condition, and the present invention has been completed by developing this movement pattern.

According to the present invention, the atomizer is rotated to reciprocate the jet stream of the high-pressure gas between the central portion and the outer peripheral portion of the preform, and the outer peripheral portion is included in one reciprocating movement cycle.
Since it is stopped for 1/18 to 1/3 cycle, it is possible to increase the heat quantity of the outer peripheral portion of the preform while obtaining the desired degree of quenching.
It is possible to reduce the vacancy layer in the outer peripheral portion of the deposit and improve the yield of the forgeable sound portion.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a comparison diagram of movement patterns used in a spray deposition method according to the present invention and a spray deposition method of a comparative example. In the present embodiment, these movement patterns are used by using the apparatus shown in FIGS. 5 and 6. The gas atomizer 5 was rotated by using a cam mechanism for drawing a preform having a diameter of about 200 mm under the following execution conditions.

Implementation conditions Material: High speed steel (SKH56) Melting temperature: 1450 ° C Melt weight: 100 kg Atomizing gas pressure: 9.9 atm Substrate rotation speed: 150 rpm Base plate position: 650 mm

Based on the preformed body produced above, the influence of the outer peripheral stop angle on the outer peripheral hole layer thickness in the method of the present invention and the comparative method (wherein the hole layer thickness is the deposit Is a value obtained by dividing the actually measured value of the hole layer thickness of the outer peripheral portion from the photograph of the central cross-section taken at a magnification of 5 times), and the preforming by the method of the present invention and the comparative method. Effect of outer peripheral stop angle on body upper half cross-sectional shape, effect of outer peripheral stop angle on yieldable sound part yield in the method of the present invention and comparative method (where sound part yield is hole layer thickness and It is a value obtained by dividing the weight of the preformed body excluding the upper cut portion by the weight of the preformed body.). These results are shown in FIGS.

In the movement patterns of the method of the present invention and the comparative method shown in FIG. 1, the horizontal axis represents the rotation angle of the cam shaft and the vertical axis represents the acceleration of the cam follower, and the rotation angle of the cam shaft ranges from 0 ° to 360 °. Corresponds to one cycle of reciprocating movement from the central portion to the outer peripheral portion of the preform. The movement pattern of the method of the present invention is different from the movement pattern of the comparative example in the case where the preform is stopped at the outer peripheral portion, that is, the outer peripheral portion stop section shown in FIG. Here is an example.

As is clear from the results shown in FIG. 2, when the outer peripheral stop angle of the preform is 20 ° or less, the outer peripheral hole layer thickness hardly changes, but the outer peripheral stop angle is
It can be seen that the hole layer thickness at the outer periphery decreases as it increases beyond 20 °, and becomes almost constant when the stop angle at the outer periphery exceeds 100 °.

However, as is clear from the results shown in FIG. 3, the shape of the upper part of the deposit changes as the outer peripheral stop angle increases, and the central portion rises when the outer peripheral stop angle is 0 ° (in the case of the comparative method). When the outer peripheral stop angle is 70 ° (in the case of the method of the present invention), it becomes almost flat and the outer peripheral stop angle is 100 °.
When it becomes larger (in the case of the method of the present invention), a dent appears near the outer peripheral portion. Therefore, the outer peripheral stop angle is 0
° or the outer peripheral stop angle exceeds 100 °, the upper part of the deposit must be cut flat during forging, and as shown in Fig. 4, the yield of the forgeable sound part of the forged deposit after cutting is Peripheral stop angle is 60 ° to 80 °, that is, within 1 cycle of movement from the center of the preform to the outer periphery
Maximum between 6 and 2/9 cycles. Further, as is clear from FIG. 4, the stop angle that can be expected to be effective in improving the yield of sound parts is within the range of 20 ° to 120 °, that is, 1 / 18th of one cycle of movement from the central part to the outer peripheral part of the preform. ~ 1/3 cycle.

In the above description, in order to facilitate understanding of the present invention, the case where the columnar preform shown in FIG. 5 is manufactured by the spray deposition method has been described as an example. The present invention is not limited to the spray deposition method of the columnar preform, but can be applied to the case of manufacturing a plate, a roll, etc. by the spray deposition method. The formation of the pore layer can be reduced.

[0018]

As described above, according to the spray deposition method of the present invention, the shape of the upper surface of the preform can be controlled and the thickness of the hole layer at the outer peripheral portion or the outer edge portion can be reduced. Thus, it is possible to improve the yield of sound parts of the forged preform.

[Brief description of drawings]

FIG. 1 is a comparison diagram of movement patterns used in a spray deposition method according to the present invention and a spray deposition method of a comparative example.

FIG. 2 is a graph showing the influence of the outer peripheral stop angle on the outer peripheral hole layer thickness in the method of the present invention and the comparative method.

FIG. 3 is a view showing the influence of the outer peripheral stop angle on the preform upper shape in the method of the present invention and the comparative method, where a is the outer peripheral stop angle of 0 °, and b is the outer peripheral stop angle. Is 70 °, and c is an upper half sectional view of the preform in the case where the outer peripheral stop angle is 100 °.

FIG. 4 is a graph showing the influence of the outer peripheral portion stop angle on the yield of a sound part that can be forged by the method of the present invention and the comparative method.

FIG. 5 is an explanatory diagram showing an example of an apparatus used in the spray deposition method.

FIG. 6 is an explanatory diagram showing an example of a cam mechanism used in a spray deposition method apparatus.

[Explanation of symbols]

1: Tandeshisu 2: Molten metal 3:
Tundish nozzle 4: Chamber 5: Gas atomizer 6:
Jet flow 7: Molten metal flow 8: Collector 9:
Substrate 10: Stepping motor 11: Preform

Claims (2)

[Claims] 1. A preform is prepared by spraying a jet stream of high-pressure gas ejected from an atomizer onto a vertically molten metal melt to atomize the same and depositing the atomized metal particles on a moving substrate. In the spray deposition method to be obtained, the atomizer is rotated to reciprocate the jet stream of the high-pressure gas between the central portion and the outer peripheral portion of the preform, and in the reciprocating movement cycle, 1/18 to A spray deposition method characterized by stopping for 1/3 cycle. 2. The spray deposition method according to claim 1, wherein the atomized metal particles are deposited on a rotating substrate to obtain a cylindrical preform.