JP4227816B2 - Powder heat treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a powder heat treatment apparatus. For example, the present invention relates to a powder heat treatment apparatus that heats and melts a composite powder having child particles attached to the surface of mother particles to form a film on the surface of the mother particles, or heats and melts thermoplastic particles to form a spheroid.
[0002]
[Prior art]
As a conventional heat treatment apparatus, a cylindrical hot air supply nozzle that blows hot air downward, a hot air supply nozzle lower end and an annular gap are provided so as to surround the lower end of the hot air supply nozzle and supplied from the hot air supply nozzle An annular powder supply header for supplying powder into the hot air and a powder supply header and a hopper arranged with a gap below the powder supply header. The hopper closes the top opening of the hopper. There is a top plate that is provided with openings at the center and peripheral edge of the top plate. (See, for example, patent literature)
[0003]
In this apparatus, heat treatment is performed as follows. First, hot air is supplied downward from the hot air supply nozzle. Next, the unprocessed powder is jetted from the annular powder supply header toward the hot air. The hot air flows almost downward, and the heat treatment of the powder is performed in this flow. Hot air and powder blown from the nozzle are introduced into the hopper through the opening at the center of the top plate. During the heat treatment, cold air is taken into the apparatus through the gap between the hot air supply nozzle and the powder supply header, the gap between the powder supply header and the hopper, and the opening at the periphery of the hopper top plate.
[0004]
[Patent Literature]
Japanese Patent Laid-Open No. 2000-52341 (FIG. 1)
[0005]
[Problems to be solved by the invention]
The hot air gradually spreads in the radial direction and mixes with the cold air to flow while lowering the temperature. However, the spread in the radial direction in the hopper is slight, and the time during which the hot air flows almost directly becomes longer than the time required for the heat treatment. In addition, the time required for the hot air to mix with the cold air and to decrease the temperature is longer than the time required for the heat treatment. For this reason, the powder remains in a high temperature flow almost directly below after the heat treatment, the adjacent processed powders are fused and condensed, and the particle size of the processed powder is a desired value. In some cases, the particle size distribution of the powder before treatment and the particle size distribution of the powder after treatment may be significantly different.
[0006]
An object of the present invention is to provide a powder heat treatment apparatus capable of preventing the fusion-aggregation of the powder after heat treatment and obtaining the processed powder having a uniform particle size.
[0007]
[Means for Solving the Problems and Effects of the Invention]
In order to solve the above-mentioned problems, the powder heat treatment apparatus of the present invention comprises a cylindrical hot air supply nozzle for blowing hot air downward, a concentric shape with a lower end portion of the hot air supply nozzle and an annular clearance between the lower end portion of the hot air supply nozzle. An annular powder supply header having a powder supply nozzle for supplying powder into the hot air blown from the hot air supply nozzle, and arranged below the powder supply header with a gap from the powder supply header. The hopper is provided with a top plate that closes the upper end opening of the hopper. Openings are formed in the center and the peripheral portion of the top plate, respectively, and the hot air containing the above powder is passed through the top plate at the center of the top plate. In a powder heat treatment apparatus that introduces cold air into the hopper through an opening, and introduces cold air into the annular gap between the hot air supply nozzle and the powder supply header, the gap between the powder supply header and the hopper, and the opening at the peripheral edge of the hopper top plate Introduced cold Those having a swirl flow generating means for swirling the.
[0008]
In the powder heat treatment apparatus having the above-described configuration, the unprocessed powder is supplied from the powder supply header into the hot air supplied from the hot air supply nozzle. After the powder is heat-treated, the flow of hot air containing the powder becomes a swirl flow under the influence of the swirled cold air. The swirl radius increases as the swirl flow becomes downstream. Therefore, the processed powders are dispersed in the flow with the larger turning radius, and the distance between the adjacent processed powders is increased, so that the processed powders collide with each other and are fused and condensed. This is prevented and suppressed. Moreover, since hot air and cold air mix with each other while swirling, the temperature of the hot air drops rapidly, and the processed powder exists in a lower temperature gas. The risk of condensation is reduced.
[0009]
The powder heat treatment apparatus may include a plurality of vertical guide vanes arranged between the powder supply header and the hopper top plate, and the cool air introduced from between the guide vanes may be swirling. This guide vane may be variable in inclination.
[0010]
In the powder heat treatment apparatus, a plurality of cold air inlets may be opened in the top plate, and a plurality of guide vanes provided in the cold air inlet may be used as the swirling cold air generating means.
[0011]
Further, a spiral guide may be provided on the outer periphery of the hot air supply nozzle in the gap between the hot air supply nozzle and the powder supply header, and this guide may be used as the swirling cold air generating means.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, with reference to FIGS. 1-2, the powder heat processing apparatus of one Embodiment of this invention is demonstrated.
[0013]
The powder heat treatment apparatus 1 includes a cylindrical downward hot air supply nozzle 4 and an annular powder supply that is arranged concentrically with the lower end portion of the hot air supply nozzle 4 with an annular gap 6 formed at the lower end portion of the hot air supply nozzle 4. A header 5 and a powder supply header 5 and a hopper 2 disposed with a gap are provided below the powder supply header 5.
[0014]
The hopper 2 includes a top plate 21 that closes the upper end opening thereof. An opening 22 is opened in the center of the top plate 21. Further, a plurality of cold air inlets 23 for introducing cold air into the hopper 2 are formed at the peripheral edge of the top plate 21 at intervals in the circumferential direction. As shown in FIG. 2, the cold air inlet 23 has an arc shape.
[0015]
An annular channel 51 is formed in the powder supply header 5, and the annular channel 51 is connected to a known powder supply source (not shown). The lower part of the inner peripheral surface of the powder supply header 5 is an inversely tapered surface having an inner diameter that increases downward. A plurality of powder supply nozzles 52 are provided on the reverse tapered surface at intervals in the circumferential direction and substantially perpendicular to the tapered surface. Further, cold air is introduced from an annular gap 6 between the powder supply header 5 and the hot air supply nozzle 4.
[0016]
A flange 53 is formed at the lower end of the powder supply header 5, and a plurality of vertical guide vanes 7 are annularly arranged between the flange 53 and the top plate 21, and the guide vanes 7, the flange 53 and the top plate are arranged. A space surrounded by 21 is a powder blowing portion 3. The center part of this powder blowing part 3 becomes the heat treatment part 3a. A gap between adjacent guide vanes 7 serves as a cold air inlet 8.
[0017]
Since the guide vane 7 swirls and sucks cold air into the powder blowing section 3 and the hopper 2, as shown in FIG. 2, one end portion is sharper than the other end portion, and the pointed portion is also sharpened. One end is located radially inward from the other end. The cold air taken in from the cold air inlet 8 is caused to flow by the guide vane 7 slightly inward from the tangential direction of the circle centering on the axis of the powder blowing portion 3 and connecting the tip inside the guide vane. Becomes a swirl flow. The guide vane 7 can be rotated around the shaft 7a, and the inclination of the guide vane 7 can be adjusted.
[0018]
The hot air supply nozzle 4 is connected to a known hot air supply source (not shown), and blows hot air at an appropriate temperature from the upper side to the lower side in the central portion of the powder blowing unit 3.
[0019]
Although not shown, a blower and a powder recovery device having a known configuration are arranged on the downstream side of the hopper 2, and the processed powder in the hopper 2 is discharged to the downstream side together with the airflow and discharged. The collected powder is collected.
[0020]
In the powder processing apparatus having the above configuration, powder is processed as described below.
[0021]
First, hot air is blown out from the hot air supply nozzle 4 to the heat treatment section 3a. When the hot air is blown out, the powder before processing is jetted and supplied together with air from the powder supply nozzle 52 toward the hot air flowing downward in the heat treatment section 3a. Further, due to the operation of the blower described above, the outside air, that is, the cool air is introduced into the hopper 2 and the powder blowing portion 3 from the cold air introduction port 23 of the top plate 21, the cold air introduction port 8 between the guide vanes 7 and the annular gap 6 for introducing the cold air. Incorporated.
[0022]
In the vicinity of the outlet of the hot air supply nozzle 4, the hot air blown from the hot air supply nozzle 4 and the cold air taken in from the annular gap 6 both flow almost downward. The pre-treatment powder is supplied in a flow of hot air that goes directly below. This flow remains almost unaffected by the cold air introduced from between the guide vanes 7, and the powder is heated to the processing temperature or higher in the flow of hot air that goes directly below it, completing the heat treatment of the powder. To do.
[0023]
By the way, the flow of the hot air is a flow almost directly below in the vicinity of the hot air supply nozzle 4, but it becomes a swirl flow because it is affected by the swirling cold air flowing around the hot air as it goes downstream. In this swirl flow, the swirl radius increases as going downstream. For this reason, the processed powder is dispersed as it goes downstream, that is, the interval between the adjacent processed powders is increased, and the processed powders are prevented from colliding and condensing.
[0024]
Further, the hot air that has turned into a swirl flow is mixed with the cold air introduced from the cold air inlet 23 of the top plate 21 and the annular gap 6 for introducing the cold air, and the temperature is suddenly lowered to become the processing temperature or lower. Is quickly cooled. Note that the cold air taken into the hopper 2 from the cold air inlet 23 of the top plate 21 flows along the inner peripheral surface of the hopper 2 and prevents the treated powder from adhering to the inner peripheral surface of the hopper 2.
[0025]
The powder heat treatment apparatus of the present invention is not limited to the apparatus of the above embodiment, and the configuration of each part can be changed as appropriate. For example, a guide vane may be provided at the cold air inlet 23 so that the cold air taken from the cold air inlet 23 becomes a swirling flow.
[0026]
Further, a spiral guide may be provided on the outer periphery of the hot air supply nozzle 4 in the cold air introduction annular gap 6 so that the cold air taken in from the annular gap 6 becomes a swirling flow.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a powder heat treatment apparatus according to an embodiment of the present invention.
2 is a cross-sectional view taken along the line II-II in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Powder heat processing apparatus 2 Hopper 21 Top plate 22 Opening 23 Open for cold air introduction (cold air introduction part)
3 Powder blowing portion 3a Heat treatment portion 4 Hot air supply nozzle 5 Annular powder supply header 51 Annular flow channel 52 Powder supply nozzle 53 鍔 6 Crevice (cold air introduction portion)
7 Guide vane 7a shaft

Claims (2)

A cylindrical hot air supply nozzle that blows hot air downward, and a concentric space with the lower end of the hot air supply nozzle and concentric with the lower end of the hot air supply nozzle to supply powder into the hot air blown from the hot air supply nozzle An annular powder supply header having a powder supply nozzle, and a hopper disposed below the powder supply header with a gap therebetween,
The hopper is provided with a top plate that closes the upper end opening of the hopper,
Openings are made in the center and peripheral edge of the top plate,
Hot air containing the above powder is introduced into the hopper through the opening at the center of the top plate,
In the powder heat treatment apparatus for introducing cold air into the annular gap between the hot air supply nozzle and the powder supply header, the gap between the powder supply header and the hopper, and the opening at the peripheral edge of the hopper top plate,
A powder heat treatment apparatus comprising a plurality of guide vanes arranged annularly between a powder supply header and a hopper top plate, and provided with swirling flow generating means for introducing cold air as swirling flows from between the guide vanes . Adjust the inclination of the guide vane and adjust the swirl speed of the cold air introduced by changing the inclination .
The powder heat treatment apparatus according to claim 1.

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