JPH02160401A - Manufacture of extra fine long metallic fiber - Google Patents

Abstract

PURPOSE:To efficiently mass-produce an extra fine long metallic fiber by performing ultrasonic vibration cutting of its edge surface while a metallic sheet coil material is rotated when extra fine long metallic fiber used as the base material of conductive plastic products is manufactured. CONSTITUTION:When extra fine long fiber is manufactured, an ultrasonic vibra tion unit 6 is mounted to a tool holder 7 and a cutting tool 5 is locked to the ultrasonic vibration unit 6. The tool holder 7 in this state is moved by a feed device provided to the main machine to press the tip 5a of the cutting tool 5 to the edge surface of a thin plate coil material 1, a specified feed, for exam ple, 3-60upsilonm/rev is given to the tool holder 7, as well as a main shaft 3 is actuat ed together, and a mandrel 2 is rotated at a specified circumferential speed, for example, 10-400m/min, and power supply of an ultrasonic wave generator 6b is simultaneously switched on, thereby the ultrasonic output generated in the ultrasonic wave generator 6b is impressed to the pilezoelectric transducer 6a of the holder 6, the ultrasonic vibration caused by this is transmitted to the tip 5a of the cutting tool 5 and resonates, and the ultrasonic vibration cut ting of thin plates 100 is performed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing ultrafine long metal fibers.

[Conventional technology and its technical issues]

Copper-based, stainless steel, and other metal fibers are used as base materials for composite materials such as conductive plastic products and electromagnetic shielding plastic products. As is well known, metal fibers can be divided into short fibers and long fibers, but long fibers are said to be preferable because their properties such as conductivity and shielding effect are proportional to the fiber content.For example, In Japanese Patent Publication No. 63-26783, a bundle of long metal fibers is used as a molding pellet for molding a plastic product in which conductive fibers are dispersed, and a thermoplastic plastic is impregnated and coated by a method such as extrusion. 1000 to 3500 in the cross section by cutting to the specified size.
It is proposed to obtain moldable pellets containing zero conductive fibers.

In order to create such composites, strict conditions are required for the long metal fibers to have a uniform cross-sectional shape and dimensions, be as thin as possible, have high strength, and have little variation, but conventional methods have not met these requirements. It was difficult to mass-produce products stably at low cost.

That is, as a method for manufacturing long metal fibers, a method of repeatedly drawing a wire rod using a die is commonly used, but the practical limit of this method, including the cost, is about 50 μm as the fiber diameter. As a countermeasure to this problem, a bundling method has been developed in which a large number of drawn wires are bundled and drawn, and this method has been applied to the production of ultrafine stainless steel fibers. However, since cumbersome pre- and post-processing steps are essential for bundling,
The above-mentioned fiber price is extremely expensive at about 30 million yen per ton.

Therefore, as an alternative method, the wire rod is hung between the left and right drums, and the wire rod is rotated while the wire rod is applied with a knife to cut the wire rod, or a thin plate of coil material is used as the base material.
A method has been adopted in which cutting is performed by rotating this and applying a cutting tool having a rake angle of 30 to 40' to the end face and a minute V groove formed on the back surface of the cutting edge.

However, all of the above methods have the following problems because the cutting edge of the tool is strongly pressed against the base material and cutting energy is applied by rotation of the base material and feeding power.

■The cross-sectional shape of the fiber tends to become irregular, the width becomes constant, and the thickness becomes thicker than the feed amount per spindle rotation (approximately three times the feed amount).

Therefore, when it is made into a composite material, there is a large variation in performance.

■If the feed rate is reduced, the cutting blade will slip, making stable cutting impossible and therefore making it impossible to produce very thin fibers.

■Since the unevenness of the free-forming surface cannot be suppressed, the strength decreases due to the notch effect, there is a lot of variation in shape and size, and there is a lot of variation in strength, and it is easy to be cut into short pieces when kneaded with plastics.

■Because the cutting edge is pressed against the base material and slides, the fibers tend to weld together due to frictional heat, making it difficult to create proper long fibers where each strand is independent.

■As a tool, an expensive special knife with a fine V-groove on the back side is essential, which increases production costs.

The present invention was devised to solve the above-mentioned problems, and its purpose is to efficiently produce ultrafine long metal fibers with uniform cross-sectional shape and dimensions, high strength, and little variation. The goal is to provide a method that can be mass-produced at low cost.

[Means to solve the problem]

In order to achieve the above object, the present invention has been developed by rotating a thin metal coil material tightly wound around a core metal around an axis.
This method involves cutting the end face of the coil material using a cutting tool that vibrates ultrasonically.

The present invention will be explained below based on the accompanying drawings.

1 and 2 show an overview of the method for producing ultrafine long metal fibers according to the present invention, and FIG. 3 shows the tool configuration.

Reference numeral 1 is a thin plate coil material which is a raw material for fiber manufacturing, and a thin plate 100 made by rolling a desired metal such as copper metal such as brass or iron metal such as stainless steel is tightly wound around a core bar 2, and the outer peripheral edge is welded or the like. Fixed. The core metal 2 is attached to the main shaft 3, supported by the other end surface or the tailstock shaft 4, and rotated around the axis at a required rotational speed.

5 is a cutting tool, and a serious cutting tool, a single-edged cutting tool, etc. are used. This cutting tool 5 is preferably configured by firmly fixing a tip 5b to a tip holder 5a by brazing or the like. and.

This cutting tool 5 is attached to an ultrasonic vibration unit 6, and the main part of the ultrasonic vibration unit 6 is mounted on a tool rest 7.

The ultrasonic vibration unit 6 is a holder 6d that houses the main body of an ultrasonic vibrator 6a such as a Langevin piezo stack type.
and an ultrasonic oscillator 6b that applies an ultrasonic electrical output to the ultrasonic vibrator 6a via a cable 6c, and the horn of the ultrasonic vibrator 6a and the cutting tool 5 are tightened with a nut 56 or the like. It is firmly fixed by any vibration transmission means. The city record holder 6d can be attached to the tool rest 7 in any way, but for example, as shown in FIG. The base 9 may be movably mounted, and the base 9 may be fixed to the tool rest 7 with bolts or the like. The ultrasonic oscillator 6
b preferably has a built-in microcomputer, automatically corrects a decrease in amplitude when it occurs, and automatically tracks a set frequency.

In producing ultrasonic long fibers, the ultrasonic vibration unit 6 is attached to the tool post 7, and the cutting tool 5 is fixed to the ultrasonic vibration unit 6. At this time, it is desirable that the vibration direction of the cutting edge substantially coincides with the cutting direction, and this can be set by attaching the holder 6 to the slider 8 at a slight inclination angle (2 to 8 degrees).

In this state, the tool rest 7 is moved by the feed device provided in the main machine, and the tip 5a of the cutting tool 5 is brought into contact with the end face of the thin coil material 1, and the tool rest 7 is moved to the required feed, for example, 3 to 60 mm.
μm/rev and drive the main shaft 3 along with it to move the core metal 2 to a required circumferential speed, for example 10 to 100 Il/ff1in.
Rotate with . At the same time, power is turned on to the ultrasonic oscillator 6b.

As a result, the ultrasonic output generated by the ultrasonic oscillator 6b is applied to the vibrator 6a of the holder 6, and the resulting ultrasonic vibration passes through the tip holder 5b of the cutting tool 5 to the tip 5a.
As a result, the thin plates 100 constituting each layer of the thin plate coil material 1 resonate at the set ultrasonic frequency.
For example, ultrasonic vibration cutting is performed at 15 to 50 KHz.

Since the cutting direction almost coincides with the ultrasonic vibration and the vibration direction is the principal force direction, the flank of the tip 5a does not collide with the end face of the thin coil material, and therefore the relative position between the end face of the thin coil material and the cutting edge is Long fibers F that do not fluctuate and are continuous without interruption are created.

In normal cutting, cutting energy is applied by rotating the fiber material and feeding power, and J11 fibers are generated by pressing the cutting edge against the fiber material, and the relative displacement between the fiber material and the cutting tool is linear at a constant cutting speed. increases to In the present invention, cutting energy is supplied by ultrasonic vibration of the cutting edge, and the tip 5a is not in constant contact with the end surface of the thin coil material 1, but is in pulsed contact for a certain period of time, and then moves away. Repeat, the amplitude is ±2~3
It is about 0 μm. As a result, the cycle in which the energy during separation is released to the surface layer of the thin coil material 1 is repeated,
Cuts easily in small increments with extremely low cutting resistance.

Therefore, even at a minute feed rate of 10 μtm/rev or less, a stable cutting state is achieved, and ultra-thin long fibers are stably created. The cross-sectional dimension of the fiber is determined by the plate thickness W of the coil material and the feed rate, so it is easy to control. For example, when the plate thickness is 0.05 m +++ and the feed rate is 0.005 mm, a fiber having a diameter of about 18 μm can be obtained.

If the feed rate is constant, the thickness of the plate can be reduced; for example, if a metal foil with a thickness of 0.02m++ is used, it will be approximately 10μ.
m, foil thickness 0.01 m5 + thickness, feed 0.
If the length is 03 mm, ultrafine long fibers of about 6 μm can be produced.

If the ultrasonic frequency is increased under these conditions, the cutting speed can be increased, thereby improving productivity.

Furthermore, according to the present invention, no unreasonable crushing force is applied to the free-forming surface of the fibers, resulting in a geometric surface roughness with small irregularities, and the strength decrease in the direction perpendicular to the fiber axis direction due to the notch effect is extremely reduced. It will be less than that. Conventional cutting methods cannot suppress the unevenness of the free-forming surface, resulting in a decrease in strength due to the notch effect.

Moreover, since the cutting edge is not strongly pressed against the surface of the thin coil material, abnormal cutting heat is not generated, and therefore, the cutting edge can be cut without forcing the thin coil material or forming any fine V-grooves on the back surface of the tip 5a. The long fibers are not welded together, and are discharged as individual long fibers corresponding to the thin plate 100, and wound up on a winding roll or the like.

Figure 4 shows approximately 400 fibers of long metal fiber F obtained by the present invention.
It shows a cross section enlarged twice, the cross-sectional shape is almost completely rectangular, and the free surface f has very few irregularities. The width W of the long metal fibers F corresponds to the thickness of the thin coil material 1, and the thickness t approximately corresponds to the amount of feed per rotation of the main shaft, so that the shape and dimensions are uniform.

〔Example〕

Next, examples of the present invention will be shown.

■As a thin coil material, brass (C
268OR) and attach it to a 140mmφ core metal with a diameter of 1
It was wound to a thickness of 0 mφ and had an outer diameter of 160 mmφ.

On the other hand, an ultrasonic vibration device shown in FIGS. 1 and 3 was used as a tool. The ultrasonic vibration system has a vibrator: Langevin piezo stack type, an oscillation method: an inverter frequency automatic tuning type, a maximum ultrasonic output of 120 W, and an oscillation frequency of 20 KHz.

The cutting tool used was a serious cutting tool tip made of carbide with a nose radius of RO, and was brazed to the tip holder.

The cutting tool was fastened directly to the horn of the vibrator using a nut. The cutting tool was mounted on the holder with an inclination so that the pitching angle was 7 to 15'', and the cutting direction and vibration direction were almost the same.The cutting conditions were: 1 peripheral speed (V):
20 to 100 m/min, feed amount per spindle rotation 3
~50 μm/rev.

■As a result, under any cutting conditions, the cross section is almost perfectly rectangular, the free surface has few irregularities, and the width matches the plate thickness.
Ultra-thin long fibers (converted diameter 18 μm) whose thickness almost matched the feed amount (minimum 5 μm in this example) were continuously created without welding together the fibers.

For comparison, we stopped the application of ultrasonic waves and attempted to manufacture long fibers using the normal cutting method.We found that the fibers with high feed rates had large surface irregularities, were curled and brittle as a whole, and were broken in some places along the length. In addition, chips that could not be called basolateral fibers were produced in which adjacent fibers were irregularly welded together. Furthermore, in a region where the feed rate is small, vibration occurs and the cutting edge slips, making cutting itself impossible.

〔Effect of the invention〕

According to the present invention as described above, long metal fibers having a uniform cross-sectional shape and dimensions, which are extremely thin, and of good quality with little decrease in strength due to notches and little variation in strength can be industrially stably and inexpensively mass-produced. It is possible to obtain excellent effects such as being able to increase the fiber density in a matrix of other materials in which the cross-sectional shape of the fibers is rectangular and uniform.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an outline of the method for manufacturing ultrafine metal long surfaces according to the present invention, Fig. 2 is an enlarged view thereof, Fig. 3 is a partially cutaway plan view of a cutting tool used in carrying out the present invention, and Fig. 4 FIG. 1 is an enlarged cross-sectional view of a long metal fiber according to the present invention. DESCRIPTION OF SYMBOLS 1... Thin coil material, 2... Core metal, 5... Cutting tool, 6... Ultrasonic vibration unit, F... Metal long fiber.

Claims (1)

[Claims] It is characterized by cutting the end face of the thin metal coil material wrapped around a core metal with a cutting tool that vibrates ultrasonically while rotating the thin metal coil material around its axis to create ultrafine long metal fibers with a nearly rectangular cross section. A method for producing ultrafine long metal fibers.