JPS6139366B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for directly producing short metal fibers for composite materials having bent ends from a molten metal or alloy (hereinafter collectively referred to as metal). Short metal fibers are mainly used to strengthen concrete and plastics by mixing them into these materials (base materials). Therefore, in order to make the composite reinforcing effect by mixing short metal fibers more effective, it is important to improve the adhesion between the fibers to be mixed and the base material. Conventionally, in order to improve adhesion, methods such as plating the surface of the fibers, creating irregularities to an appropriate degree of roughness, and bending the ends into a dogleg shape have been adopted. However, these methods complicate the process and increase manufacturing costs. Under these circumstances, the present inventor developed a method for directly producing short metal fibers by rapidly cooling molten metal (liquid quenching method).
By adopting an improved method, we succeeded in manufacturing short metal fibers with bent ends simply and inexpensively. By the way, the conventionally proposed methods for directly producing metal fibers from molten metal can be roughly divided into (1) melt spinning method and (2) melt extraction method. be. The former attempts to produce continuous fibers by applying back pressure to the molten metal and causing it to collide with a cooling substrate that moves at high speed to rapidly cool it. Furthermore, this method can be divided into centrifugal quenching, single roll method, twin roll method, etc. depending on the cooling method. On the other hand, the molten metal drawing method is a method in which no pressure is applied to the molten metal, and the solidified portion is drawn out (or scraped out) by contacting the molten metal with a cooling substrate. Among these methods, in the case of the molten metal spinning method (1), by narrowing the nozzle hole for ejecting the molten metal, fibers having a narrow width and a flat cross section can be continuously obtained. The present invention relates to a method for efficiently producing short metal fibers having at least one bent end by improving the above-described melt spinning method, and a cooling body used in the production. The present invention will be explained in detail below with reference to the drawings. FIG. 1 shows the main parts of a cooling body used in the present invention, in which a is a plan view and b is a side view. 1 in the diagram
is the substrate of the cooling body, and the entire body is formed in the shape of a roll, drum, or endless belt. 2
are V-shaped grooves with a depth h ₁ bored on the surface of the substrate 1 at predetermined intervals (flat portions 4). Also, Figure 2 a,
b is a short metal fiber manufactured by the cooling body shown in FIG. 1, 5 is a main body, 6 is a bent part, and 7 is a hook at the tip. FIG. 3 shows a case in which a V-shaped ridge 3 is provided on the surface of the substrate 1 according to the present invention, in which a is a plan view of the main part and b is a side view. Fourth
Figures a and b show the product (short metal fiber). Further, FIG. 5 shows a case in which a V-shaped groove 2 and a V-shaped ridge 3 following the V-shaped groove 2 are provided on the surface of the substrate 1 according to the present invention, where a is a plan view of the main part and b is a side view. It is. Figures 6a and 6b show the products. In order to carry out the method of the present invention, for example, a cooling body (for example, roll-shaped) having V-shaped grooves 2 provided at predetermined intervals on the surface of a substrate 1 as shown in FIG. 1 is moved (rotated) at high speed, and Alternatively, a molten alloy may be jetted onto the surface of the substrate 1 from a nozzle (not shown). At that time, the molten metal flows along the surface of the substrate 1, flows into the V-shaped groove 2, and is rapidly solidified. As a result, Figure 2a
Alternatively, as shown in b, it is possible to produce a short metal fiber having a bending part 6 or a bending part 6 and a hook part 7 at the tip of the main body 5. Further, in the present invention, a V-shaped ridge 3 as shown in FIGS. 3a and 3b is provided on the surface of the substrate 1 of the cooling body, and the molten metal is heated while the cooling body is moved (rotated) as in the case of FIG. 1. When the molten metal is ejected onto the surface of the substrate 1, the molten metal flows along the gentle slope of the V-shaped ridge 3 and rapidly solidifies. Therefore, short metal fibers as shown in FIGS. 4a and 4b are obtained. In addition, as shown in FIGS. 5a and 5b, the substrate 1 of the cooling body
V-shaped groove 2 and subsequent V-shaped ridge 3 on the surface of
When the molten metal is spouted onto the surface of the substrate 1 while moving (rotating) the cooling body in the same way as in the case of FIG. 1, the molten metal flows down along the gentle slope of the V-shaped ridge 3. Since it flows into the character-shaped groove 2 and is rapidly solidified, short metal fibers as shown in FIGS. 6a and 6b are produced. In addition, it is preferable that the V-shaped groove 2 and the V-shaped ridge 3 in the present invention have dimensions as described below.

[Table] Groove depth or ridge height h ₁ or h ₂ is 0.3
If it is smaller than mm, the bent part 6 of the manufactured short metal fibers may be too short and hardly contribute to improving the adhesion, and if it is larger than 5 mm, it will be difficult to separate it from the cooling body, making continuous production impossible. It may disappear. Also, the width k ₁ or k ₂ of the groove or ridge is
If it is narrower than 0.5 mm, there is a risk that the manufactured fibers will be continuous, and even if short fibers are formed, the bent portions may be too short and no longer contribute to improving adhesion. Also, the angle α of the slope of the groove or ridge is 30
If it is less than 90°, it may not become short fibers, and if it is more than 90°, it is difficult to produce grooves or ridges.
A range of 30 to 90° is preferred. On the other hand, the angle β of the slope is related to the angle of the bent part of the produced short fiber,
If the angle is too small, the effect of improving adhesion will hardly appear, so it is preferable to set the lower limit to about 20°. Further, the length of the short fiber main body 5 can be arbitrarily set depending on the purpose. That is, by setting the intervals (flat parts 4) between the V-shaped grooves 2 (V-shaped ridges 3) of the cooling body to a desired interval, the length of the main body 5 can be made to a desired length. For example, when used to strengthen concrete, etc., 5 to 40
Approximately 0.3 mm is appropriate, and when used as a reinforcing material for brake pads, shorter lengths (for example, at least 0.3 mm) are appropriate. Also, the pressure when spouting molten metal onto the cooling body is
0.05 to 3 Kg/cm ² , and the moving speed of the cooling body (peripheral speed in the case of a roll or drum) is approximately 2 to 40 m/sec. The fibers can be made amorphous and have good strength and corrosion resistance. Furthermore, by selecting the type of alloy, it is also possible to impart excellent electromagnetic shielding properties or vibration damping properties to the produced short fibers. Furthermore, in the present invention, short fibers having double bent portions as shown in FIG. 2b, FIG. 4b, and FIG. Obtainable. In this case, the adhesion to the composite material base material can be further improved. Next, examples of the present invention will be shown. Example 1 A roll made of Cu-1%Cr alloy was used as a cooling body, and V-shaped grooves were formed on the surface of the roll as shown in Figure _1.
= 1.2mm, k ₁ = 1.0mm, α = β = 67.5°, = 10mm
It was formed using the specifications of A molten metal having an alloy composition of Fe ₇₀ Cr ₁₀ P ₁₀ C ₁₀ (at%) is rotated at a circumferential speed of 25 m/sec at a pressure of 0.5 Kg/cm ² from a nozzle with a hole diameter of 0.5 mm and 10 holes. It was sprayed onto the roll surface and rapidly solidified to produce short fibers with a width of 1 mm, a thickness of 30 μm, a main body length of 10 mm, a bent part of about 1 mm, and one end bent at a bending angle of about 60°. The X-ray diffraction image of this short fiber revealed that it was amorphous, showing a halo pattern. Also
It had enough viscosity that it would not break when bent 180°. Example 2 As a cooling body, a V-shaped ridge as shown in FIG. 3 was provided on the surface (h ₂ = 1.2 mm, k ₂ = 1.0 mm, α = β = 67.5
゜, = 10 mm) using a Cu roll,
A molten metal with an alloy composition of Fe ₇₂ Cr ₈ P ₁₃ C ₇ (at%) was
A nozzle of 0.5 mm and 10 holes was sprayed at a pressure of 0.5 Kg/cm ² onto the surface of the roll rotating at a circumferential speed of 18 m/sec, and rapidly solidified.
A short fiber was produced with a main body length of 10 mm, a bent part of about 1 mm, and one end bent at a bending angle of about 60°. The X-ray diffraction image of this short fiber showed a halo pattern, indicating that it was amorphous. Embodiment 3 As a cooling body, a V-shaped groove and a V-shaped ridge (h ₁ = h ₂ = 2.4
mm, k ₁ = k ₂ = 2.0 mm, α = β = 67.5°, = 10
molten SUS430 stainless steel is applied to the roll using a Cu roll having a diameter of 0.8 mm and 6 holes at a pressure of 0.3 Kg/cm ² and rotating at a circumferential speed of 15 m/s. When ejected onto the surface and rapidly solidified, it turned out to be 1.5 mm wide, 60 μm thick, and 10 mm long.
Short fibers having bent portions at both ends with a bending angle of about 65° and a bending angle of about 65° were obtained. As explained above, according to the present invention, short fibers suitable for being mixed into concrete, plastic, etc. to increase their strength can be easily produced. Although the above embodiments have been described using rolls as cooling bodies, it goes without saying that short fibers similar to those in the above embodiments can be obtained even when endless belts are used as cooling bodies.

[Brief explanation of the drawing]

In FIGS. 1, 3, and 5, a is a plan view and b is a side view of the cooling body used in the present invention. Also, Fig. 2 a, b, Fig. 4 a, b,
Figures 6a and 6b are side views showing short fibers obtained by the present invention. 1: Substrate, 2: V-shaped groove, 3: V-shaped ridge,
4: flat part, 5: main body, 6: bent part, 7: hook part.

Claims (1)

[Scope of Claims] 1 A cooling body having a plurality of V-shaped grooves or V-shaped ridges arranged at predetermined intervals on its surface is moved, and molten metal or alloy is jetted and collided with the surface of the cooling body to rapidly cool it. A method for producing short metal fibers for composite materials, which comprises coagulating the process to produce short fibers with bent ends. 2. A cooling body having a plurality of pairs of V-shaped grooves followed by inverted V-shaped ridges arranged at predetermined intervals on the surface is moved, and molten metal or alloy is jetted and collided with the surface of the cooling body to rapidly cool it. A method for producing short metal fibers for composite materials, which comprises solidifying the fibers to produce short fibers bent at both ends. 3 V-shaped grooves, V-shaped ridges, or V-shaped grooves followed by inverted V-shaped ridges are arranged at predetermined intervals on the surface of a roll-shaped (or drum-shaped) or endless belt-shaped substrate. A cooling body for producing short metal fibers for composite materials, characterized by: