JPH11158510A - Method for rolling powder and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder rolling method with which powder in formed into a plate-like or bar-like formed product having small electric resistance and high bonding strength among the powders and hardly developing the breakage by bending, etc., without damaging the characteristic possessed by the powder, and the apparatus therefor. SOLUTION: The objective powder having electric conductivity at least on the surface and the lower m.p. metal powder than that of the objective powder, are pre-mixed to form the electric conductive powder 9. The electric conductive powder is poured between one pair of rolls 12 arranged parallel to each other and electricity is supplied between the rolls, and the objective powders are welded by melting only the low m.p. metal powder by the resistant heating through the electric supply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for rolling a powder into a plate or a rod while maintaining the properties of the powder.

[0002]

2. Description of the Related Art There has been known a method of manufacturing a thin plate by molding a powder of a hard-to-work metal material such as tungsten or molybdenum at room temperature and high pressure, and further through processing steps such as sintering, hot forging, and rolling. ing. However, such a method has problems that the processing steps are complicated, various facilities are required, the yield is low, and the product cost is high. Therefore, a powder rolling means capable of directly manufacturing a thin plate by directly rolling the powder in a high temperature state without going through processing steps such as sintering, hot forging, and rolling has been devised and filed (for example, Japanese Unexamined Patent Publication No. Hei. -115302, JP-A-7-138610).

As shown in FIG. 3, the powder rolling means flows a conductive powder 3 between two rolls 1 and heats the powder by applying a current between the rolls. It is to be rolled. In this figure, 2 is a hopper, 4 is a formed rolled plate, and 5 is a power source.

[0004]

However, in the conventional powder rolling means, since the powder is completely melted and integrated, the specific surface area is greatly reduced, and the characteristics (eg, electrical characteristics, However, there is a problem that the characteristics and biological treatment function are almost impaired.

[0005] Therefore, conventionally, in order to form the powder into a rod or plate while maintaining the properties of the powder,
A plastic binder is used as a bonding agent. However, in this case, since the conductivity of the plastic binder is low, the electrical resistance of the molded product increases, and when used as an electric component, heat generation and conductive loss increase, so that the current capacity can be limited and energy consumption can be reduced. There are problems such as loss.

Further, when a powder having a catalytic performance or a powder having a biological treatment function by bacteria or the like is similarly molded, the bonding strength of a plastic binder is low, and
There was a problem that the molded product was easily broken when bent or folded. Further, when the ratio of the plastic binder is increased to increase the strength, the powder surface is covered with the binder, and the specific surface area is reduced, so that the characteristics are deteriorated.

The present invention has been made to solve the above problems. That is, an object of the present invention is to form a powder into a plate or rod-shaped molded product that has a small electric resistance between the powders, a high bonding strength, and is not easily damaged by bending or the like, without impairing the properties of the powders. It is an object of the present invention to provide a powder rolling method and an apparatus therefor.

[0008]

According to the present invention, a target powder having at least a surface having conductivity and a low melting point metal powder having a lower melting point than the powder are mixed in advance to form a conductive powder, Flowing the conductive powder between a pair of rolls,
A powder rolling method is provided, wherein a current is applied between the rolls, and only the low-melting-point metal powder is melted by resistance heating by the current application to weld between the target powders. According to a preferred embodiment of the present invention, it is preferable to previously perform a surface modification for covering the surface of the target powder with a metal material.

According to the powder rolling method of the present invention, the conductive powder obtained by mixing the target powder and the low-melting metal powder is energized to melt only the low-melting metal powder and weld the target powder. It is formed into a plate or rod having a structure in which the contact portion of the target powder is welded with the low-melting metal solidified (solidified). Thereby, since the low melting point metal is welded between the target powders, the electric resistance is reduced. In addition, the target powder other than the contact part has the characteristics (electrical characteristics,
(Catalytic property or biological treatment function) is maintained as it is, and a void remains between the target powders, so that a fluid (gas or liquid) can freely flow, and heat release and reactivity can be maintained. it can. Further, since the low melting point metal has higher bonding strength and flexibility as compared with a plastic binder, it can be easily processed without being damaged by bending or the like.

Further, according to the present invention, there are provided a pair of rolls provided in parallel with each other, and a power supply facility for supplying a current between the rolls. A conductive powder mixed with a low melting point metal powder having a melting point lower than that flows into the rolls, an electric current is applied between the rolls, and only the low melting point metal powder is melted by resistance heating by the electric current to weld the target powders. A powder rolling apparatus characterized by the following.

According to this structure, the conductive powder is supplied between the rolls, where the current generated by the current flow causes the powder to generate heat due to its internal resistance, and only the low-melting-point metal powder having a low melting point dispersed in the powder is dissolved. The powder can be combined. The pair of rolls are compressed with each other so that the electric resistance of the conductive powder located between the rolls becomes sufficiently small, and the conductive powder passes through the rolls. The passed low-melting-point metal is condensed and solidified in the passed conductive powder to fix the target powder therebetween, and can be formed into a plate or rod shape.

According to a preferred embodiment of the present invention, the lower end has an opening having opposing edges parallel to the axis of the roll, a hopper for supplying powder between the rolls, and a vibrator for applying vibration to the hopper. And a driving device for rotating and driving the rolls, and a winding machine for winding a molded product formed into a plate or a rod. With this configuration, the powder material (conductive powder) is continuously supplied to the hopper, and the hopper is vibrated by a vibrator, and is smoothly supplied between the rolls from the hopper.
Furthermore, powder rolling can be continuously performed by winding the molded product formed by the winding machine.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, common parts are denoted by the same reference numerals, and redundant description is omitted.
1 is an overall configuration diagram of a powder rolling device according to the present invention. As shown in this figure, the powder rolling apparatus 10 of the present invention includes a pair of rolls 12 provided in parallel with each other, and an energizing facility 14 for energizing between the rolls 12. Further, the apparatus 10 includes a hopper 16 having an opening having opposite edges parallel to the axis of the roll 12 at its lower end and supplying powder between the rolls, a vibrator 18 for applying vibration to the hopper 16, The apparatus includes a driving device 20 that rotationally drives the motor 12 and a winding machine 22 that winds a molded product formed into a plate or a rod. In this figure, reference numeral 23 denotes a pinch roll.

The roll 12 is a rolling roll, and also serves as one electrode (anode or cathode) for energization. The roll 12 is preferably water-cooled by cooling water passing therethrough so as not to be damaged by heat. In addition, the roll 12
, The roll itself may be heated without cooling. Further, the rolls 12 are rotationally driven inward by a drive device 20 (for example, a motor) to roll the conductive powder 9 supplied from above. The rolling force in this rolling is set so that the electric resistance of the conductive powder 9 located between the rolls is sufficiently small.

Power supply equipment 14 includes a power supply 14a and electric wires 14b.
(Cable), a voltage is applied between the rolls 12, and a predetermined current flows through the conductive powder 9 located therebetween. This current value is set so that the conductive powder 9 itself generates heat due to internal resistance, and only the low melting point metal powder 8 having a low melting point dispersed in the powder is dissolved to bind the target powder 7. The power supply 14a may be either a DC power supply or an AC power supply.

With the above-described structure, the conductive powder 9 is supplied between the rolls 12, where the powder generates heat due to its internal resistance due to the electric current, and only the low melting point metal powder 8 having a low melting point dispersed in the powder. Can dissolve and bind the target powder. Further, the powder material (conductive powder 9) is continuously supplied to the hopper 16, and the hopper 16 is vibrated by the vibrator 18 to smoothly supply the powder from the hopper 16 to the rolls. By rolling up the molded product formed at 22, powder rolling can be performed continuously.

Further, according to the method of the present invention, the conductive powder 9 comprises the target powder 7 having at least a surface having conductivity,
It is formed by previously mixing low melting point metal powder 8 having a lower melting point than this powder. The target powder 7 is preferably a metal powder having conductivity itself, but the present invention is not limited to this, and may be a ceramic powder or the like. When ceramic powder is used, it is preferable to previously perform surface modification for covering the surface of the target powder 7 with a metal material.

The target powder 7 is preferably a powder that can be used as an electric component, a powder having a catalytic performance, a powder having a biological treatment function with bacteria or the like, but the present invention is not limited to these. The space between the powders may be used as a filter or the like.

FIG. 2 is a diagram schematically showing a bonding structure between particles. In this figure, (A) shows a bonding structure according to the present invention, and (B) shows a bonding structure using a conventional plastic binder. In this figure, 7, 8 are
A target powder and a low melting point metal are used, and 6 is a plastic binder.

According to the powder rolling method of the present invention described above,
Conductive powder 9 obtained by mixing target powder 7 and low melting point metal powder 8
2A, only the low melting point metal powder 8 is melted and the target powders are welded to each other, so that the melting and solidification (solidification) of the low melting point metal 8 makes contact with the target powder as shown in FIG. The part is formed into a plate or rod shape having a welded structure. Therefore, since the space between the target powders 7 is welded with the low melting point metal 8, the electric resistance is reduced. In addition, the target powder 7 other than the contact portion has characteristics (electrical characteristics, catalytic characteristics,
Or the biological treatment function) is kept as it is, and a void remains between the target powders, so that the fluid (gas or liquid)
Can be freely circulated, and heat radiation and reactivity can be maintained. Further, since the low melting point metal 8 has a higher bonding strength and is more flexible than a plastic binder, it can be easily processed without being damaged by bending or the like.

On the other hand, in the conventional bonding structure, when the ratio of the binder 6 is increased, the powder surface is covered with the binder 6, the specific surface area is reduced, and the characteristics are deteriorated. Further, since the binder 6 has lower conductivity and lower bonding strength and flexibility than the low melting point metal 8, it is clear that the performance is low in all of the electric resistance, the bonding strength, the bending and the like.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

[0023]

As described above, the powder rolling method and apparatus according to the present invention have a low electric resistance between powders, a high bonding strength, and are unlikely to be damaged by bending or the like, without impairing the properties of the powders. It has excellent effects such as being able to form a powder into a plate or rod-like molded product.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a powder rolling device according to the present invention.

FIG. 2 is a diagram schematically showing a bonding structure between particles.

FIG. 3 is a schematic view of a conventional powder rolling device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roll 2 Hopper 2a Opening edge 3 Powder 4 Board 5 Power supply 6 Plastic binder 7 Target powder 8 Low melting metal 9 Conductive powder 10 Powder rolling device 12 Roll (rolling roll) 14 Current supply facility 16 Hopper 18 Shaker 20 Drive device 22 Winding machine 23 Pinch roll

Claims (4)

[Claims] An object powder having at least a surface having conductivity and a low melting point metal powder having a lower melting point than the powder are mixed in advance to form a conductive powder, and the conductive powder is placed between a pair of rolls. A powder rolling method, wherein the powder is flowed, current is applied between the rolls, and only the low-melting metal powder is melted by resistance heating by the current application to weld the target powder. 2. The powder rolling method according to claim 1, wherein a surface modification for covering the surface of the target powder with a metal material is performed in advance. 3. A pair of rolls provided in parallel with each other, and an energizing facility for energizing between the rolls, whereby a target powder having at least a surface having conductivity, and a low melting point having a lower melting point than the powder. The conductive powder mixed with the melting point metal powder is allowed to flow between the rolls, an electric current is applied between the rolls, and only the low melting point metal powder is melted by resistance heating by the energization to weld between the target powders. Powder rolling equipment. 4. A hopper for supplying powder between the rolls having an opening having opposite edges parallel to the axis of the roll at the lower end, a vibrator for applying vibration to the hopper, and rotating the rolls. The powder rolling device according to claim 3, further comprising: a driving device; and a winder that winds a molded product formed into a plate or a rod.