GB2118080A - Apparatus for producing flake particles - Google Patents

Abstract

Discrete small cooling surfaces (6) are arrayed on the surface of a rotatable or endlessly movable heat extracting member (10). The discrete surfaces (6) are defined by one oblique set of parallel grooves (4a) crossed by another set of parallel grooves (4b) in different direction. An opening of a nozzle means (12) is directed toward the outer surface of the heat extracting member (10). A stream (2) of molten metal is projected upon the continuously passing discrete surfaces (6); the heat of the molten material is extracted by each discrete surface (6), and the metal solidifies on it as a discrete flake particle. <IMAGE>

Description

SPECIFICATION Apparatus for producing flake particles This invention relates to apparatus for producing flake particles by projecting a stream of molten (e.g. metallic) material upon the rotating or moving surface of a heat extracting member, thereby extracting the heat from the molten material so as to solidify it into a large number of flake particles. The thus solidified flakes may, for example, be removed from the heat extracting member by means of centrifugal force.

Heretofore, various kinds of flake particle making apparatus have been provided which produce flake particles by contacting molten metal with the rotating surface of a heat extracting member and allowing the molten metal to solidify thereon.

The most typical known to us is disclosed by U.S. Patent 4,21 5,084. There the heat extracting member is a rotating drum, upon the outer surface of which a continuing stream of molten material is projected. The outer rotating surface is constructed to have a number of serrations formed substantially parallel to the axis of rotation of the drum. When a continuing thin stream of molten metal is projected upon the surface of three serrations, the heat contained in the metal is extracted by the serrations, resulting in solidification of the metal into a large number of flake particles.

Accordingly, if it is required to increase the production rate of flake particles by carrying out the process in parallel, it becomes necessary to lengthen each rotating drum and to provide a plurality of nozzles.

However, it is also demanded to effect fine and correct adjustment of the nozzle opening to obtain flake particle as fine and as equal in size as possible.

Such adjustment is not only accompanied by technical difficulties, but such a fine nozzle also results in troubles with respect to its service life, process control, and costs.

Since such metal flake particles are most generally mixed into plastics for use as electromagnetic interference shielding material, it is also required to be capable of being uniformly mixed and dispersed.

However, flake particles produced according to such conventional apparatus as mentioned contain considerable amounts of deformed particles or smaller sized one although they are generally made square in shape, thereby obstructing uniform mixing and dispersion of the flake particles into plastics material.

The main cause for bringing about such a non-uniformity in size and shape of the particles is considered to be that the serrated surface of the heat extracting member is higher at the rear part of each upper surfaced serration than at the front part of one with respect to the direction of the rotation of the rotating member; thereby the molten metal is liable to be repelled or shed such that the phenomenon hinders smooth transferring of the molten metal onto the heat extracting member.

As typical prior art for obtaining fine solidified metal particles, there have been found several U.S.

Patents such as Nos. 3710842, 3838185, 3896203,3904344, and 3908745. However, all of these prior art inventions relate to methods or apparatus for producing filaments or fibres.

What is desired in the making of flake particles is high production efficiency with low cost, using apparatus which is readily controllable in operation, which can be operated for a long service period, and which is capable of producing flake particles of uniform shape and size.

The present invention provides apparatus for producing flake particles from a stream of projected molten material, comprising, an endless heat extracting member having an outer periphery carrying a plurality of heat extracting sections, a molten material reservoir with a nozzle or nozzles for directing the molten material onto the outer surface of the heat extracting sections, and means for driving the heat extracting member to cause the heat extracting sections to pass the nozzle(s), wherein; each heat extracting section constitutes a unit discrete cooling surface defined by two adjacent first parallel grooves extending obliquely with respect to both edges of the heat extracting member and two second parallel grooves extending in a different direction from the first parallel grooves, the heat extracting sections are constituted by an integrated member comprising the unit discrete cooling surfaces successively arrayed both along and transversely to the direction in which the heat extracting member is driven, and at least two sides of each discrete cooling surface cross a line normal to the direction in which heat extracting member is driven.

The heat extracting member may be constructed as either of drum type or of endless belt type.

The discrete surfaces provided on the heat extracting member can be formed by merely cutting grooves.

Moreover, these discrete small surfaces, regardless of their shape, either formed as faces arrayed along the direction of rotation, flat faces normal to the diametrical line of the heat extracting member, or as planes higher at the rear portion with respect to the direction of rotation while being sectioned by an edge line into two surfaces inclining down both to the axial and rotational direction, they all receive molten material without repelling it from their surface.

The discrete small surfaces formed by crossing many number of grooves as mentioned above usually take the form of parallelogram, but they can be made as triangular planes by cutting each triangle by grooves formed parallel to the axis of rotation.

Since these small surfaces are arranged in an array in axial direction and further in number of arrays in peripheral directions one after another, the nozzle or orifice for projecting molten material onto these surface can be made to have a length extending over the almost entire axial length of said heat extracting member such that the molten metal can be applied through a single nozzle or orifice onto all of the discrete small surfaces in the array.

By virtue of the fact that the molten material can be projected concurrently onto a plurality of these discrete small surfaces through the orifice or nozzle as mentioned above, projected molten material is concurrently cooled and solidifies on each discrete small surface.

As explained above, the molten material projected through the nozzle solidifies and formed into a number of flake particles closely similar to the shape and size of the discrete small surfaces formed on the outer periphery of the heat extracting member, and yet with greatly increased production efficiency.

In addition, since the nozzle or orifice of the present invention is able to be made as one having width corresponding to the axial length of the heat extracting member, it is not required to make the diameter or caliber very small as done in the conventional ones.

This makes adjustment or size controlling of the nozzle far much easier and contributes to lengthen the service life of the apparatus as a whole as well as in lowering the running cost.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 A is a partly cross sectioned elevational view showing a typical embodiment of the present invention.

Fig. 1 B is a cross sectioned front view of a nozzle opening and the shape of the molten material being ejected through the opening.

Fig. 2 is a front view of the surface of a heat extracting member in the form of a drum.

Fig. 3 is a perspective schematic view showing the way of forming a number of small discrete surfaces on the surface of heat extracting member by a number of spirally formed grooves formed on the surface thereof.

Fig. 4 is a cross sectioned elevation showing a typical embodiment of the present invention.

Fig. 5 is an enlarged side view showing a part of the heat extracting member.

Fig. 6 is a perspective view showing a stream of the molten material being ejected onto the surface of the heat extracting member.

Fig. 7A is an enlarged fragmented plan view showing a part of the heat extracting member.

Fig. 7B is a plan view showing the shape of a flake particle formed by the present invention.

Fig. 8 is a schematic elevation showing. a. part of a heat extracting member of cylindrical drum type having a number of small discrete cooling surfaces formed on the outer surface.

Fig. 9A through Fig. 9D are fragmented sectional.views showing several type nozzle openings.

Fig. 10 is a plan view showing the surface of a heat extracting member of an embodiment.

Fig. 11 is a cross sectional side view taken along line 11-11 of Fig.10.

Fig. 12 is an enlarged perspective view showing some of the discrete small cooling surfaces of th( embodiment of the present invention Fig. 1 3 is a front view showing another way of forming discrete small cooling surfaces different from those previously described. Flg. 14 is a partially cross sectionalfront view showing the present invention provided with a plurality of orifices.

Fig. 1 5 is a partly perspective cross sectional view showing a plurality of nozzle for projecting molten material.

Fig. 1 6 is an enlarged sectional view showing the part of the nozzle.

Fig. 17 is a partly cross sectioned plan view taken along line 17-17 of Fig. 16.

Fig. 1 8 is a cross sectional elevation of the-protruding nozzle provided with a heating means.

Fig. 1 9 is a schematic perspective view showing a manner of forming a large number of small discrete cooling surfaces by a number of looped grooves.

Fig. 20 is a schematic front view showing a part where the two looped grooves intersect with each other.

Fig. 21 is a schematic side elevation of a heat extracting member having each discrete small cooling surface is formed normal to each diametral line of the drum.

Fig. 22 is a schematic side elevation showing the portion of the discrete small cooling surface being connected by a radius to a gently inclined wall of a groove.

Fig. 23 is a schematic front view, wherein grooves of one group of grooves out of two groups crossing each other are formed in parallel with the axis of the heat extracting drum.

Fig. 24 is an enlarged side view showing a heat extracting drum composed of an outer peripheral member and a separately formed inner body portion.

Fig. 25 is an enlarged side view showing an endless belt type heat extracting member composed of an outer heat extracting layer and a separately formed inner supporting member.

Fig. 26 is a schematic illustration of an apparatus for producing flake particles employing an endless belt type heat extracting member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLE I In Figs. 1 through 23, and 24, numeral 10 denotes a heat extracting member formed as a drum of substantially round cross section, the outer surface of which is made of a material having high heat conductivity and good wear resistance such as copper chromium alloy.

A coolant, for example, water can be introduced into the interior of the heat extracting member 10. The heat extracting member or drum is rotated by means of a shaft 1 Oa having a through hole (not shown) through which the coolant is introduced.

In Fig. 1, numeral 11 is a driving means coupled to said shaft 1 Oa so as to rotate the heat extracting member 10 at high speed of rotation. The driving means 11 is consisting of an electric motor, transmission means and other well known devices and is capable of adjusting the rotational speed of the heat extracting member of drum.

The shaft 1 Oa is connected to a means (not shown) for supplying the coolant through a swivel (not shown).

In Figs. 1 through 4, 1 3 denotes a means for supplying molten material disposed above the heat extracting member 10, and is generally composed of a reservoir 1 7 made of a refractory material or materials such as graphite and/or quartz, wrought steel or iron and a heater 18 disposed around said reservoir 17.

At the bottom of the reservoir 1 7, a nozzle 1 2 having an elongated opening extending along the axis of the heat extracting member 11 is provided, through which a continuing stream of molten material such as aluminum alloy is projected in the form of a band or a ribbon upon the outer peripheral surface of the heat extracting drum 10.

Since the nozzle 12 extends over the surface of the heat extracting member along the axis of the heat extracting member, the molten material 2 is ejected as a continuous stream, as shown in Fig. 1 , on the entire surface of the width of the heat extracting member in the form of a band or a curtain.

Numeral 1 9 is a conduit which communicates a gas supply source, not shown, to the molten metal reservoir 17. Gas such as air or argon is supplied from the gas supply source.

In the drawing, numeral 21 is a temperature measuring device to detect the temperature of the molten material contained in the reservoir.

Explanation will not be made on the outer surface of the heat extracting member 10.

In Fig. 1 , a large number of grooves 4a of one group are engraved on the outer surface of the heat extracting member 10, in parallel with each other extending obliquely with a predetermined angle of inclination between both axial ends of the extracting member 1 0. Also a large number of grooves 4b of the other group are engraved on the surface of the heat extending member in a similar manner but with an angle of inclination in different direction from that of the grooves 4a, such that each of the grooves 4b crosses the groove 4a, finally, the groups of the groove 4a and groove 4b define a large number of small discrete heat extracting or cooling surface 6 on the outer peripheral surface of the heat extracting drum such that a plurality of the cooling surfaces 6 is arrayed in both the rotational and axial directions of the heat extracting member 10.

In this embodiment, each of the grooves 4a and 4b defining a unit small discrete heat extracting surface is directed to cross a line 1 Ob on the surface depicted parallel to the axis of the heat extracting member 10.

As particularly shown in Fig. 3, grooves 4a and 4b are formed along a pair of imaginary lines 4c and 4d going spirally around the cylindrical surface 1 Oc defining the outer peripheral surface af the heat extracting member 1 0, the entire or part of the grooves cross each other and form a large number of small discrete heat extracting surface.

In Fig. 2 these grooves 4a and 4b are positioned at an equal angle 6i, 62 of 450 to the both axial end faces, namely, to the axis of the heat extracting members 10 at the equal spacing, accordingly, the shape of a small discrete cooling surface 6 defined by two pairs of grooves 4a and 4b takes the form of a square having four equal sides of length M as shown in Fig. 7A.

However, the shape of the small discrete cooling surface 6 is not limited to be a square as shown in the example of Fig. 7A and the angle of each of the 01, and 62 can be selected within the ranges, as shown in a formula: 50 < (61or62) < 850 When both of the angles 0, and 62 are set equal but other than 450, the small discrete surface will become a rhombus, when the angles 0, and 62 are set different, the discrete cooling surface will become a quadrangle other than a square or rhomboid.

Since the small discrete cooling surfaces 6 are formed directly on the substantially cylindrical surface of the heat extracting member 10, they take the cross sectional configuration along the surface of the member 10 as shown in Fig. 8, in addition a gentle- slope in front of the small discrete cooling surface and the crossing of the grooves 4a and 4b are connected so as-to define a radius contour r.

Since the discrete surface 6 is formed to have such a configuration, molten material projected upon this portion will exactly ride on each of the discrete small cooling surfaces without being repelled, even if the heat extracting member is rotated at a considerably high speed.

As can be clearly understood from Figs. 4, 5 and 8, the grooves 4a and 4b of the preferred embodiment are defined by two sloped walls, the one at the rear side with respect to the rotation of the heat extracting member is gently sloped, while the other wall immediately forward is formed to constitute an upstanding wall of half conduit trough.

By virtue of such sectional configuration, forward edge of each discrete small cooling surface can be prevented from rebounding or repelling the molten impinging material continuously ejected from the orifice 12.

As shown in Fig. 6, the grooves 4a and 4b defining the discrete small surface, of course, can be made as those having a trough like simple configuration.

When a molten material 2 is projected as a continuous stream through the nozzle 1 2 upon the small discrete cooling surfaces 6 of the heat extracting member 1 0 while it is being rotated, the molten material, as shown in Fig. 4, simultaneously contacts to the plurality of discrete small surfaces 6 so as to be extracted its heat by the small cooling surfaces 6 and solidifies thereon and is disintegrated, and peels off due to the centrifugal force of the rotation of the member 10, into flake particles 23 and then fall into a pile.

Although the nozzle 12 of this embodiment has a length extending almost over the axis of the heat extracting member 10 such that the molten material 2 can be projected from the single nozzle 12 located at the portion above the heat extracting member, simultaneously on a plurality of said small surfaces 6 aligned in the axial direction, but it is not required to follow this type of construction.

Beneath the heat extracting member 10, a conveyor 22 is positioned to receive thereon flake particles 23 laid as a pile, and the conveyor is driven from time to time to transfer the thus piled flake particles into a box 22b positioned immediately below the front end of the conveyor. In the drawing numeral 22a is a partition plate for partitioning the right side and left side of the conveyor, and 24 is a wiper wheel which wipes and removes the flake particles 23 which are still kept left on the small cooling surfaces 6 without being stripped off by the centrifugal force imparted by the rotation of the heat extracting member 10.

Production tests have been conducted by using the apparatus described above and in the following test conditions.

As a result, flake particles 23 of substantially square shape each having equal sides or two pairs of equal sides as shown in Fig. 7B were obtained.

A. Material and Size of the Heat Extracting Member 10

Copper-chromium alloy Material (containing 1.5% by weight of Cr) Diameter (D) 300.0 mm Length (L) 40.0 mm Number of spiral grooves 4a and 4b 560 (number of division) Depth of the grooves 4a and 4b (H) 0.12 mm Width of the grooves 4a and 4b (N) 0.4 mm Length of the one side of the 0.79 mm discrete small surface (M) Length of the diagonal of the 0.12 mm small surface (S) B. Condition of Test Running

r Example I Example II Kind of Molten Material Aluminium of 99.7% purity Aluminium of 99.7% purity Atmosphere of Melting Argon gas Air Heating Temperature 8500C 7800C Size of Nozzle Opening 10.0(1) x 0.4 mm(b) 15.0(1) x 0.35(b) Pressure of Projection 0.6 kg/cm2 above 0.8 kg/cm2 above atmospheric pressure atmospheric pressure Number of Rotation of the 1800 rpm 2200 rpm heat extracting member 10 Peripheral speed of the 28.3 m/S 34.5 m/S above member Material of the wiper Cotton Cloth Cotton Cloth C. Results (1) According to the Example I, flake particles 23 each having a length of a side M of 0.79 mm and thickness T of 30-40 form, were obtained at a production efficiency of 48 kg per hour and the average weight of one flake particle was proved to be 0.060 mg.

(2) According to the Example 11, 68 kg/hour of square flake particles 23 were obtained each having a length of one side M = 0.79 mm and thickness T = 30 to 35 microns (cm).

As can be clearly observed from the examples, flake particles of very fine surface area can be obtained continuously, according to the present invention.

In addition, since the orifice or nozzle 1 2 has a considerably wide opening, there is no fear of clogginy of the nozzle 12 and is readily handled or operated with very less change of troubles.

Preferably, aithough the length of the opening of the orifice or nozzle 1 2 can be selected within a range of from 1 mm to 50 mm, longer one also can be used, similarly preferable width of the opening may be 0.1 to 5 mm but is not limited to this value mentioned above.

Also the shape of the opening of the nozzle or orifice can be modified, as shown in Fig. 1 B to have its middle portion narrowed in space as compared with that at its both axial ends, with an intention to restrain the thickness of the ejected molten material at the middle portion so as not to become larger due to the less extent of resistance to projection as compared with higher resistance to the ejection of molten material at the both axial end of the opening.

In the examples explained above, aluminum was used as a molten material, however, various other material such as copper base or nickel base alloys, iron, amorphous alloys and the like.

EXAMPLE II Fig. 14 shows a plurality of nozzles or orifices 12 extending along the axis of the heat extracting member 10, and in the construction of this device all other parts excepting these nozzles are the same as shown in Fig. 1 , so further detailed explanation will be omitted.

Fig. ? 4 also shows that each of the streams 2 of the molten material spreads over a plurality of small discrete surfaces 6.

EXAMPLE Ill Figs. 1 5 through 1 8 show an embodiment using a nozzle 1 2 having a projected portion 1 2c detachably attached to a molten material reservoir 1 7.

Especially in Fig.15, the reservoir 1 7 is arranged above the heat extracting member 10 and is provided with a first heating means 1 8 using a burner for maintaining the temperature of the molten material received in the reservoir and a heating jacket surrounding the heating means 1 8.

In the drawing, 24 is a wiper wheel coupled to the driving means 11 through a shaft 24a.

The heat extracting member 10 in this example has a construction the same as that of the Example I, so it will not be explained again.

Now, the nozzle 12 will be explained in detail.

The molten material reservoir 1 7 has, at its bottom, an opening and the nozzle 12 is detachably fixed to the bottom of the reservoir being in alignment with the opening.

The nozzle 12 is composed of a flange 12a, and a projecting cylindrical portion 1 2b formed integral with the flange 1 2a and defining at its tip end a projecting slot 1 2c of narrow elongated rectangular shape for projecting the molten material such as aluminum or aluminum alloys received in the reservoir 17 in the form of a band or a curtain.

As also shown in Fig. 1 6, this nozzle 12 is positioned, at first, by aligning its axially extending hole 1 2d with the opening of the reservoir 17 and then tightly secured to the bottom of the reservoir by the aid of a fixture 30 consisting of a plurality of holding blocks 32 each having at least one oblong aperture.

a plurality of stud bolts 31 threaded into the bottom of the reservoir 1 7 and the same number of tightening nuts 33.

The distance between the upper surface of the heat extracting member 10 and the lowermost end of the projection opening 12c is selected for aliowing adjustment within the range of at least 0.05 mm up to 50 mm.

In Figs. 1 6 and 17, numeral 26 denotes a second heating means using a burner positioned such that the flame coming from the burner can heat the projection 1 2b so as to prevent the molten material 2 flowing through the nozzle 1 2 from being cooled by the temperature of the surrounding air down to below the required temperature.

Numeral 22 is a reflector plate which surrounds the nozzle 12 and reflects the amount of heat supplied by the second heating means 26 toward the nozzle 1 2 so as to uniformly heat the projection 12b of the nozzle 12.

Such a reflecting plate 22 in practical use is fixed tightiy to the holding block 32 and is bent into a semicircular cross section to cover almost half periphery of the projection 12b.

EXAMPLE IV Fig. 1 8 shows another form of heating means for the nozzle 1 2 having a projection portion 12b.

In this instance, the second heating means 26 is integrally provided at the projecting portion 1 2b of the nozzle 1 2, namely, the outer surface of the projecting portion 1 2b is covered by a heat insulation material 27 within which a heater 28 is embedded so as to heat the nozzle 12 for preventing lowering of the temperature of the molten material 2 passing through the nozzle-from occurring. As an actual heating means, heating element using a nichrome wire can be used.

By constituting the nozzle 1 2 as shown above, meritorious effect similar to that obtained by the above example Ill can be obtained.

EXAMPLE V Alternatively, as shown in Fig. 24, heat extracting member 10, can be composed of an outer peripheral portion 1 Od and a main body portion 1 Oe for supporting the peripheral portion, so as to allow replacement of the outer peripheral portion in case of possible wear, damage and/or repairing.

EXAMPLE VI Fig. 21 shows an embodiment wherein the small cooling surfaces 6 are formed normal to the diametric line to the center of the each surface 6, by forming the small cooling surfaces in this manner, molten material impinging on these small surfaces can be exactly applied thereon without being repelled or rebounded.

If the gentle slope at the rear side of each groove with respect to the direction of rotation and each flat part of the small surface 6 is connected by a curved face having a radius r as shown in Fig. 22, molten material projected on these small surface can be applied more exactly thereon without being repelled or rebounded even if the heat extracting member is rotated at a considerably high speed.

EXAMPLE VII Shown in Fig. 23 is another form of a discrete small cooling surfaces 6. In this example, a heat extracting member 10 is also formed on a cylindrical drum, one of the two group of grooves crossing each other is spirally formed as 4a and the groove of the other group represented as 4b is formed in parallel with the axis of the heat extracting member 10, thus the surface 6 constitutes a rhomboid.

EXAMPLE VIII As shown in Fig.13, each of the number of rhomboids defined by two kinds of grooves 4a and 4b is further separated by a groove 4f to constitute a unit discrete cooling surface 6 of substantially triangular shape.

EXAMPLE IX Shown in Fig. 1 9 is an embodiment following a different manner of forming discrete small surfaces 6.

In this embodiment, the heat extracting member 10 is also formed as a cylindrical drum.

Grooves 4a extend obliquely along the surface of the drum at a certain angle, while the remaining grooves 4b similarly extending but at another angle, both between the two opposite axial ends of the drum.

They are constituted by engraving them as a plurality of endless loops along the lines 4c and 4d, respectively, which are formed around the cylindrical surface 1 Oc.

In order to constitute discrete small cooling surfaces in uniform size and shape as many as possible, each loop of groove is required as shown in Fig. 20, to have a portion having a sharp point and deviated from the remaining part of the looped groove.

All of the looped groove are also required to have such deviated portions with their sharp points being aligned on the same line parallel to the axis. Such manner of positioning the looped grooves is required such that a pair of grooves 4a and 4b can form a discrete small cooling surface 6 as shown in Fig. 20, and thus enabling all other pair of grooves to form similar surfaces 6.

EXAMPLE X Figs.10,11 and 12 show another embodiment, having different type discrete small cooling surfaces 6 instead of aforementioned surface of square, rhomboid or other quadrangles shape sectioned by a large number of grooves 4a and 4b shown in the preceding examples.

Each of such cooling surface 6 is composed of two gently sloped triangular faces 6a and 6b at the upper surface part and inclining down in the direction of rotation as well as to the axial direction of the heat extracting member 10, and these faces 6a and 6b intersects each other to constitute a crest edge line or ridge 6c running in the direction of rotation.

The triangular surfaces 6a are formed on groove engraved along lines 4a, while the surfaces 6b on grooves on lines 4b.

Rearmost end of the gently sloped face 6a terminates into a steep wall 5b like a cliff defined by a crest line 9a, similarly, the sloped face 6b terminated into a steep wall 5a being defined by a crest line 9b.

A pair of gently sloped faced 6a and 6b constitute a discrete small convex cooling surface 6 for forming thereon a flake particle, while each steep wall 5a or 5b acts as a step for separating each discrete convex surface 6 from all other neighbouring ones successively formed along grooves 4a and 4b, one after another.

In the drawings, numeral 23 denotes a flake particle solidified on the small convex cooling face 6, while numeral 2 denotes a stream of molten material being projected and falling upon same small surface 6. A number of such gentle slopes 6a and 6b and the steep walls 5b and 5a are formed, by cutting parallel grooves 4b, at first and then by cutting or grinding off a half portion of the thus formed grooves in transverse direction along 4b, or vice versa. This crossed machining will result in many number of convex surfaces 6 separated by steps 5a and 5b.

EXAMPLE Xl In Fig. 9A, nozzle 12 is formed as having a circular opening, while in Fig. 9B the nozzle 1 2 of circular opening is directed upward toward the heat extracting member 10 disposed above the nozzle 12 to inject the molten material 2 upwardly from a molten material supplying means 13 positioned below the heat extracting member 1 0.

Fig. 9C shows another type of nozzle, in which outlet of the opening is placed being very close to the upper outer surface of the heat extracting member 10, while Fig. 9D shows still another type of nozzle arrangement, wherein nozzle opening is positioned being directed to and very close to the lower surface of the heat extracting member 1 0 disposed above the nozzle, so as to minimize oxidation and/or nitriding of the molten material during its flowing onto the discrete surfaces 6.

EXAMPLE XII Fig. 26 shows another embodiment in which the heat extracting member 10 is arranged as an endless type one.

As shown in Fig. 25, the heat extracting member 10 is composed of a body portion 1 Oe made of a flexible endless metal belt, around the outer surface of which an outer endless surface member 1 Od are detachably fixed by means of a number of protrusions and grooves 1 Of being disposed in the direction transverse to the movement of the belt.

On the surface of the outer endless surface member 1 Od, discrete small cooling surfaces 6 are formed by forming a number of parallel grooves of one group extending obliquely to the direction of movement and forming the same number of parallel grooves of the other group which obliquely crossing the former grooves.

The heat extracting member 10 of this example is supported by a driving pulley 40 supported on an axis 1 Oa, a pair of follower pulley 41 and 42, and a tension pulley 43.

A means for supplying a molten material 13 is disposed above and the nozzle 12 is directed to the position where the follower pulley 41 turns the heat extracting member 10.

In the drawing, numeral 44 is a cooling box into which a coolant is introduced to cool the device.

A wiper wheel 24 is disposed between the follower pulley 41 and 42 so as to be in contact with the outer surface of the heat extracting member 10 together with a box 22b to surround the part lower than the follower pulley 41.

As can be clearly understood from the drawing, the box 22b and the portion where the follower pulley 41 confronting the nozzle 12 are substantially shielded from the interior of the cooling box 44.

By moving the heat extracting member 10 constructed as mentioned above while cooling it, molten material was ejected through the nozzle 12 upon the heat extracting member, the stream of molten material contacts the small surfaces 6 of the heat extracting member, and solidifies thereon into a great number of flake particles 23.

In this example, too, the discrete small surfaces formed on the endless belt type heat extracting member can be optionally made as, quadrangles, triangles or any other configuration.

Nozzle 12 can also be optioned to have any desired configuration.

Claims (22)

1. Apparatus for producing flake particles from a stream of projected molten material, comprising, an endless heat extracting member having an outer periphery carrying a plurality of heat extracting sections, a molten material reservoir with a nozzle or nozzles for directing the molten material onto the outer surface of the heat extracting sections, and means for driving the heat extracting member to cause the heat extracting sections to pass the nozzle(s), wherein: each heat extracting section constitutes a unit discrete cooling surface defined by two adjacent first parallel grooves extending obliquely with respect to both edges of the heat extracting member and two second parallel grooves extending in a different direction from the first parallel grooves, the heat extracting sections are constituted by an integrated member comprising the unit discrete cooling surfaces successively arrayed both along and transversely to the direction in which the heat extracting member is driven, and at least two sides of each discrete cooling surface cross a line normal to the direction in which heat extracting member is driven.

2. Apparatus as claimed in claim 1, wherein the second parallel grooves extend obliquely at the same angle as but inclining opposite to the first parallel grooves, thereby defining each discrete cooling surface as a parallelogram.

3. Apparatus as claimed in claim 1, wherein the second parallel grooves extend normal to the direction in which the heat extending member is driven, thereby defining each discrete cooling surface as a parallelogram.

4. Apparatus as claimed in claim 1 , wherein each discrete cooling surface is formed substantially as a quadrangle and is sectioned into two halves of substantially triangular shape by a groove formed normal to the direction in which the heat extracting member is driven.

5. Apparatus as claimed in any of claims 1 to 4, wherein the nozzle extends in the transverse direction of the heat extracting member with a length sufficient to apply the same molten material onto the discrete cooling surfaces aligned on the transverse direction.

6. Apparatus as claimed in any of claims 1 to 4, wherein a plurality of the nozzles are aligned transversely of the heat extracting member.

7. Apparatus as claimed in any preceding claim, wherein the or each nozzle is constructed as a nozzle assembly comprising a flange to be detachably fixed to the reservoir, a protruding body member integrally formed with the flange and directed toward the heat extracting member, and a nozzle opening provided at the tip end of the body member.

8. Apparatus as claimed in claim 7, wherein the body member is provided with a heating means.

9. Apparatus as claimed in any preceding claim, wherein the spacing between the opening of the or each nozzle and the cooling surfaces is in the range from 0.05 mm to 50 mm.

10. Apparatus as claimed in claim 9, wherein the spacing is adjustable within the said range.

11. Apparatus as claimed in any of claims 1 to 10, wherein each groove is composed of a wall at the front side with respect to the direction of driving, and a wall at the other side at the rearward of the direction of driving and having an inclination more gentle than the former wall.

12. Apparatus as claimed in any of claims 1 to 10, wherein each groove is composed of a wall at the front side with respect to the direction of driving, and a wall at the other side at the rearward of the direction of driving and having an inclination more gentle than the former wall.

13. Apparatus as claimed in any of claims 1 to 10, wherein each groove is composed of a wall at the front side with respect to the direction of driving and a wall at the other side at the rearward of the direction of driving and having an inclination more gentle than the former wall and the discrete cooling surface is connected to the latter wall with a curved surface.

14. Apparatus as claimed in any preceding claim, wherein the heat extracting member consists of an outer portion and an inner body portion supporting the outer portion, and the outer portion is detachably fixed to the inner body portion.

1 5. Apparatus as claimed in any preceding claim, wherein the heat extracting member is constructed in the form of a drum.

1 6. Apparatus as claimed in claim 1 5, wherein the grooves are formed along a plurality of endless loops around the drum.

1 7. Apparatus as claimed in claim 15, wherein the grooves are formed along a spiral line around the drum.

1 8. Apparatus for producing flake particles as claimed in claim 15, wherein the grooves are formed along a plurality of spiral lines around the drum.

1 9. Apparatus as claimed in any of claims 1 5 to 18, wherein the discrete cooling surfaces are formed normal to the diametral line of the drum.

20. Apparatus as claimed in any preceding claim, wherein the heat extracting member is constructed as a substantially exact circular cylindrical dum and each discrete cooling surface is formed as an arcuated face along the circular peripheral surface of the drum.

21. Apparatus as claimed in any of claims 1 to 14, wherein the heat extracting member is constructed as an endless belt passing around at least two shafts.

22. Apparatus for producing flake particles, substantially as described with reference to any embodiment illustrated in the accompanying drawings.