JPH04258362A - Spray forming method - Google Patents

Abstract

PURPOSE:To precisely measure the height of the pre-formings and to calculate the piling yield at the same time by arranging the distance measuring device with using the radio wave on upper side of the base plate and executing with spray forming while measuring the height of the pre-formed body. CONSTITUTION:The distance measuring device with using the radio wave of about 10-300mm of the wave length is used, the dispersion with the metallic granule is low extremely, if the spray forming method is used, the distance can be measured high precisely. For example, if the load cell, etc., is used commonly and the weight of the molten metal 2 is measured, the piling yield can be grasped.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spray molding method.

0002

[Prior Art] The spray molding method can obtain a uniform fine structure with high density, and the molding process can be simplified compared to the conventional powder metallurgy method, so it is a method that can be expected to significantly improve productivity. It is attracting attention.

The apparatus shown in FIG. 1 is exemplified as an apparatus for obtaining, for example, a block-like preform using the spray molding method. A tundish 1 contains molten metal 2,
It flows down by gravity through the tundish nozzle 13 into the chamber 3 having a non-oxidizing atmosphere. Above tundish 1
A gas atomizer 4 is disposed below the gas atomizer 4, and high-pressure inert gas ejected from the gas atomizer 4 becomes a jet stream 5 and is blown onto the molten metal stream 6 to atomize it. The atomized metal particles are collected in the lower collector 7.
The liquid is deposited in a semi-solidified state on the substrate 8 set at 200° C. and gradually solidifies. The collector 7 can be moved up and down using a stepping motor 10 or the like as a driving source, and by lowering the collector 7 according to the amount of deposited metal particles, the distance between the tundish nozzle 13 and the top surface of the deposit can be kept constant. It is possible to obtain a block-like preform 9 with an increased stacking height while maintaining the same.

0004

[Problems to be Solved by the Invention] In order to obtain a good preform in the above-mentioned spray molding method, it is important to keep the top surface of the deposit in a semi-solidified state and finish it into the target shape. It is greatly affected by various parameters such as molten metal temperature, molten metal speed, atomizing gas pressure, atomizing gas flow rate, and spray distance, and these require strict control. In performing such control, one of the important issues is to maintain the height of the top surface of the preformed body constant as a prerequisite.

[0005] A conventional general spray molding apparatus has a load cell 11 disposed below a tundish 1 as shown in FIG. 1, calculates the total amount of molten metal 2 flowing down from the measured load change, Estimating the weight of the preform on the substrate 8 from past deposition yield 11 (ratio of metal particles collected on the substrate to the total amount of atomized metal particles),
This was converted into the height of the preform 9. However, the height of the preform obtained by the above method is not necessarily accurate, and there has been a demand for improved accuracy.

The above deposition yield is calculated by measuring any two of the following: (1) the weight of the preform, (2) the weight of the residual molten metal, and (2) the weight of the recovered metal after the completion of spray molding. It is desirable for production control to be able to grasp the deposition yield during the spray molding operation.

[0007] Therefore, as a method for measuring the height of a preform during spray molding, a method using a distance measuring device using a laser has been adopted. However, even if a laser has a high resolution in a normal environment, in an atmosphere where metal particles etc. are diffused, such as in the chamber of a spray molding machine, the light waves will be scattered and highly accurate measurement values will not necessarily be obtained. The problem is that it cannot be used.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a spray molding method in which the height of a preform can be measured with high accuracy and the deposition yield can be calculated at the same time.

[0009]

[Means for Solving the Problems] The present invention achieves the above objects by spraying a jet stream of high-pressure gas onto molten metal flowing vertically downward to atomize it, and depositing the atomized metal particles onto a substrate. In a spray molding method for obtaining a preform by deposition, a distance measuring device using radio waves is disposed above the substrate, and spray molding is performed while measuring the height of the preform. It is.

0010

[Operation] The distance measurement method using laser has a wavelength of 0.5
It uses light waves of about 1 μm, and although it has high resolution, it is susceptible to scattering by water vapor and dust, and high accuracy cannot necessarily be achieved in an atmosphere where metal particles are diffused, such as in the chamber of a spray molding machine. .

The present invention uses a distance measuring device using radio waves with a wavelength of about 10 to 300 mm, and the scattering caused by the metal particles is extremely small, making it possible to measure distances with high accuracy even when used in spray molding. It is possible.

Furthermore, as shown in FIG. 1, for example, a load cell 11
If the reduction in weight of the molten metal 2 is measured using the above methods, it is also possible to grasp the deposition yield during spray molding.

[0013] The present invention does not limit the method of measuring distance using radio waves, and examples thereof include an antenna drive method, a slide short method, a PIN-diode method, and a two-frequency mixed modulation method.

Next, a distance measuring method using a simple FM radar using the slide short method, for example, will be explained.

As shown in FIG. 1, a transmitting/receiving antenna 20 is disposed above the board and connected to a radio wave oscillator, detector, and computer (not shown). The radio waves generated by the radio wave oscillator are transmitted from the transmitting section of the antenna 22 to the preformed body 9.
Transmit to the surface.

The radio waves reflected on the surface of the preform 9 are caught by the receiving section of the antenna 20 and sent to a detector. The detected data is converted into distance data by a computer as follows. As shown in Figure 2, an arbitrary time t
If the frequencies after 1 lapse are fT for the transmitted wave and fR for the received wave, the difference between fT and fR is proportional to the propagation delay time τ. Here, the distance from the antenna 22 to the preformed body 9 is d
, the speed of the radio wave is c, the relationship τ=2d/c holds true, and the distance d can be found from the propagation delay time τ. The height of the preform may be calculated from the distance d obtained in this way and the height of the substrate surface.

[0017]

EXAMPLE A block preform was produced under the conditions shown in Table 1.

[0018]

[Table 1]

The height of the preform at 60, 120, and 180 seconds after the start of spray molding was measured using an FM radar measuring instrument, which is one of the distance measurement techniques of the radio wave method, and at the same time, the spray molding was stopped. The preform was immediately taken out of the chamber and its height was measured.

As a comparative example, a Michelson laser interferometer, which is a distance measurement technique using a laser application method, was used.
The height of the preform was measured in the same manner as in the examples. Table 2 shows the values obtained by dividing the numerical values obtained by each method by the measured values and the average error.

[0021]

[Table 2] As described above, according to the method according to the present invention, it is possible to improve measurement accuracy.

[0022]

[Effects of the Invention] Since the present invention is configured as described above, it is possible to provide a spray molding method that can accurately measure the height of a block-like preform and calculate the deposition yield if necessary. .

[Brief explanation of the drawing]

FIG. 1 is a schematic illustration of a spray molding method.

FIG. 2 is an explanatory diagram showing the measurement principle of an FM radar.

[Explanation of symbols]

1 Tundish 2 Molten metal 3 Chamber 4 Gas atomizer 5 Jet flow 6 Molten metal flow 7 Collector 8　　　　Substrate 9 Preformed body 10 Motor 11 Load cell 13 Tundish nozzle 20 Transmitting/receiving antenna

Claims (1)

[Claims] Claim 1: A spray molding method in which a jet stream of high-pressure gas is sprayed onto a molten metal flowing vertically downward to atomize it, and the atomized metal particles are deposited on a substrate to obtain a preform. A spray molding method characterized in that a distance measuring device using a distance measuring device is disposed above the substrate, and spray molding is carried out while measuring the height of the preform.