JPS6317571B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The short fibers of the present invention have properties such as high elastic modulus, high abrasion resistance, good electrical and thermal conductivity, and good wettability and sinterability, and are suitable for use in composite materials and porous sintered materials. The present invention relates to a method for producing ultrafine short fibers of copper alloy suitable for use as a base material for binding materials.

Fibers, especially metal fibers, have properties such as thermal conductivity and electrical conductivity, so they can be used as friction materials such as clutches and brake linings, as base materials for various structural composite materials such as reinforced plastics, conductive plastics, and shielding materials, as well as for filters and heat exchangers. It is expected to be widely used as a base material for porous sintered products such as pipes and heat exchanger components, as well as sound absorbing materials with different materials impregnated or mixed into the pores, sound insulating materials, Oiles metal, and abrasive materials. .

By the way, the metal fibers used for this type of application are generally required to be short and fine fibers with a diameter of 100 microns or less and a length of 10 mm or less, and to have good physical properties such as tensile strength.
To obtain such short fibers, the conventional method is to roll a cast ingot to make a wire rod, use this as a starting material and draw it with a die, etc., and repeat this drawing and annealing several times until the desired diameter is reached. The method used was to stretch the fibers and then shred the long fibers.

However, this method requires a very labor-intensive process of rolling, drawing, annealing, drawing, and shredding to obtain the desired fibers, resulting in low productivity.Moreover, each step of rolling, drawing, and annealing requires a large-scale process. There were some drawbacks, such as the need for equipment, which led to extremely high production costs.

The present invention was developed through research to eliminate the drawbacks of the conventional method for producing ultrafine short metal fibers, and its purpose is to provide ultrafine short fibers made of copper alloy having the above-mentioned characteristics. The objective is to provide a method that allows for extremely simple, inexpensive, and efficient mass production.

Another object of the present invention is that the fiber shape is not a simple straight line, but is curved in whole or in part in the fiber axis direction, and exhibits good properties as a base material for composite materials, porous sintered products, etc. It is an object of the present invention to provide a method for producing irregularly shaped ultrafine short fibers of copper alloy very efficiently.

In order to achieve the above object, the present invention rotates a block made of a relatively low ductility copper alloy such as brass, and at the same time, a plurality of blades having a length equal to the desired fiber length are attached to the copper alloy block in steps. By applying tools arranged parallel to each other through shapes, irregularities, or grooves, and turning by setting the specified tool rake angle, feed, and cutting speed, ultrafine short fibers with a non-circular cross section are produced at each cutting edge. Furthermore, by carrying out the same method with a tool having a curved surface or unevenness on the rake face and/or flank face of each of the blade parts, the fiber length direction becomes curved or uneven. The ultra-fine short fibers are created in each blade part. However, in any of the methods of the present invention, short fibers are created by utilizing natural cracks in the material, and methods of applying chatter vibration or forced vibration from the outside are not adopted.

The present invention will be specifically described below with reference to the accompanying drawings.

Figures 1 and 2 show an embodiment of the method for producing short copper alloy fibers according to the present invention. 1 is a copper alloy block which is a raw material for producing short fibers, and this copper alloy block is made of brass. A typical material with relatively low ductility is processed into a rod or column shape by a conventional method such as casting.

In order to obtain copper alloy short fibers, the axial end of the copper alloy block 1 is grasped with a holding means such as a chuck, and the copper alloy block 1 is held through this holding means.
The cutting edge portion 4 of the tool 3 is rotated at a predetermined speed and number of rotations, and has a predetermined rake angle θ on the end face 11 of the copper alloy block 1 and has a specially processed blade portion.
The cutting edge 4 is brought into contact with the circumferential surface 12 of the copper alloy block 1 to give a feed f in the direction of the block axis, or the cutting edge 4 is brought into contact with the circumferential surface 12 of the copper alloy block 1 to give a feed in the direction perpendicular to the block axis. .

In this way, as is clear from FIG. 2a, a thin layer 5 of the copper alloy block begins to accumulate on the rake face 7 of the cutting edge 4 in response to the rotation of the copper alloy block 1 and the feed f of the tool 3. , when this reaches a certain level, cracks 10 occur due to an unstable phenomenon and are sheared and separated, resulting in acicular short fibers 6 having a length L corresponding to the cut l.
is created.

However, at this time, if the tool rake angle θ, cutting speed V, and feed f are not appropriate, the collected thin layer will flow out for a long time along the rake face, resulting in curved or curled flow chips, or the free surface The chips become serrated chips with a series of serrated irregularities on the sides, making it impossible to obtain the desired short fibers.

Therefore, the present invention provides a tool rake angle θ, a cutting speed V
and feed f to predetermined conditions, basically, Tool rake angle θ: Approximately 0 to -40° Cutting speed V: Approximately 86 to 276 m/min Feed rate f: Approximately 0.05 to 0.3 mm/ rev.

First, the tool rake angle has a large effect on fiber formation. Tools used for normal cutting have a large rake angle on the positive side to reduce the power load on the machine body to encourage the discharge of flowing chips, and are equipped with a breaker at the cutting edge for worker safety. A method is used to break up long flowing chips. However, such ordinary cutting chips vary in shape (length, thickness) and do not have characteristics suitable for use as composite fibers.

The present invention uses a tool with a negative rake angle, which is considered to be harmful according to the conventional wisdom of cutting, and uses this tool to strongly compress the copper alloy pieces 5' that have been scraped and accumulated on the rake face 7. Fibers are generated by promoting natural cracking (shearing) of the material, and for this reason, the upper limit of the tool rake angle is set to 0° in the present invention.

However, if the tool rake angle is made extremely negative, serrated chips tend to occur in areas where the feed rate is large, and flow-type chips occur in areas where the feed rate is small. Therefore, the lower limit of rake angle is −
40°, and thin and hard fibers can be produced at 0 to -40°.

Next, as the feed amount is decreased, the fiber cross-sectional area tends to become smaller, and the smaller the feed and the more negative the rake angle, the thinner the short fibers can be. However, if the feed rate is too small, the side edges in the longitudinal direction of the fibers tend to form a series when leaving the cutting edge 4, resulting in a flowing chip. Should be set to a range. According to actual studies conducted by the present inventors, it was found that the feed rate should be at least about 0.05 mm/rev when the rake angle is within the above range. Furthermore, the upper limit is approximately 0.3 mm/rev for the purpose of producing short fibers with a small cross-sectional area.

Next, the cutting speed affects productivity, and the faster the cutting speed, the more fibers can be produced. However, on the other hand, the faster the cutting speed is, the narrower the fiber generation area becomes. This is thought to be due to an increase in the cutting speed, which increases the fracture strain of the material and makes it difficult for the chips to separate. Generally, the tool rake angle is 0 to -40°,
When the feed rate is 0.05mm/rev or more, it is approximately 86~
The speed is 276m/min.

The above are the basic conditions, but the inventors actually investigated and found that within the framework of the above basic conditions, the relationship between the tool rake angle, feed amount, and cutting speed is set as follows. It was found to be the most effective. In other words, when the tool rake angle is approximately 0 to -10°, the lower limit of the feed amount is approximately 0.07 to 0.1 in the entire cutting speed range.
mm/rev and the value gradually increases as the tool rake angle becomes more positive.

When the tool rake angle is more than about -10° and up to about -20°, the cutting speed should be lower than the upper limit, and the lower limit of the feed rate should be within the range of about 0.05 to 0.07 mm/rev and the tool rake angle is close to positive. The value increases gradually as the cutting speed increases.

When the tool rake angle exceeds approximately -20° and reaches approximately -30°, the cutting speed should be approximately 158 m/min or less, and when the cutting speed is at the lower limit, the feed rate should be approximately 0.05 mm/rev or more,
When the cutting speed is approximately 158m/min, the feed rate should be approximately 0.05~
During 0.075mm/rev, the cutting speed is from the lower limit to approx.
Between 158m/min, the feed rate is approximately 0.05mm/rev.
In addition, the upper limit of the feed rate is set to a smaller value as the cutting speed is faster and the tool rake angle is more negative.

When the tool rake angle is negative and exceeds approximately -30°, the cutting speed is set to approximately 158 m/min or less, and when the cutting speed is at the lower limit, the feed rate is approximately 0.05 to 0.1 mm/rev, and the cutting speed is approximately 158 m/min. min sets the feed amount to approx.
When the cutting speed is between 0.05 and 0.075 mm/rev and the cutting speed is between the lower limit and about 158 m/min, the feed rate should be adjusted to about 0.05 to 0.1.
Between mm/rev, the faster the cutting speed, the smaller the value.

By setting such conditions, the desired copper alloy short fibers can be produced with a high yield.

Furthermore, in addition to the above, the present invention is characterized by using a specially machined tool for the cutting edge portion. As shown in Figures 3 to 10, this tool has a plurality of blade parts 31 with a length l equal to the length of the fiber to be manufactured, arranged in a step-like shape, in a concave-convex shape, or in a parallel manner through grooves. It is.

First, in the embodiment shown in FIG. 3, an inclined blade part 31 is created by forming notches 32 every length l from one end of the cutting blade part 4 to the other end, and a predetermined rake is formed on each blade part 31. The angle θ and the lateral relief angle λ are given, and the cutout 32 has a predetermined cutout amount m as shown in FIG. 3a in order to improve the separation of the fibers.

In the embodiment shown in FIG. 4, blade portions 8 each having a length l equal to the desired fiber length are provided at the tip of the tool holder 8.
Chips 82 with 1 are installed in a stepped manner, and adjacent chips are provided with a predetermined step m corresponding to the notch amount shown in FIG.
This is the one with the . In this embodiment of FIG. 4,
Since a predetermined rake angle θ can be set for each chip or for each predetermined chip group, it is possible to effectively cope with changes in peripheral speed due to a decrease in the diameter of the copper alloy block 1 due to turning, and it is possible to adjust the rake angle θ for each chip or for each chip group. A large amount of short copper alloy fibers can be created at once.

Next, in FIG. 5, while the blade portions in FIGS. 3 and 4 are inclined with respect to the axis of the copper alloy block, each blade portion 31 is configured perpendicular to the axis of the copper alloy block,
Each blade part 31 is connected by an inclined notch 32. FIG. 6 shows a throw-away version of the one shown in FIG. 5.

In FIG. 7, the cutting edge 4 is provided with a concave and convex blade part, that is, a rectangular or ladder-shaped blade part 31 having a length l equal to the desired fiber length is alternately protruded and recessed. This is what I did. FIG. 8 shows this in a throw-away type.

In FIG. 9, right-angled grooves 33 are formed in the slanted cutting edge 4 at intervals corresponding to the desired fiber length, thereby arranging a plurality of slanted blades 31 in parallel. It is.

Figures 10a to 10d show cutting edges 4 suitable when the turning direction is set on the circumferential surface 12 of the copper alloy block and the feed is set in the radial direction, and its configuration is the same as that described above. , the same reference numerals are shown and the explanation will be omitted.

Figures 11a and 11b show examples of the tool used in the second invention of the present invention, and Figures 3 to 10
The rake face 7 and/or flank face 7' of each blade part 31 constituting the cutting edge part 4 in the figure is made into a curved surface 9,
Alternatively, the uneven surface 9' may be formed by a curve, a straight line, or a combination thereof. Note that FIG. 11 shows some examples, and it goes without saying that the invention is not limited to these.

In any case, according to the present invention, a copper alloy block 1 is turned using a tool 3 as illustrated in FIGS. 3 to 11. In this way, a thin layer on the surface of the copper alloy block 1 is continuously scraped off by each of the plurality of blades 31 of the tool 3 in contact with the copper alloy block 1, but the copper alloy block 1 is made of a material with relatively low ductility; The predetermined tool rake angle, feed rate, and cutting speed are set, so that the thin layer that is raked is maintained at a constant rate, rather than being continuously flowed out and forming flowing chips or serrated chips. When the copper alloy block swells up to a certain amount and is compressed, a crack appears almost along the interface between the scraped thin layer and the surface layer of the copper alloy block, and the copper alloy block is instantaneously broken and separated along this crack, as schematically shown in Figure 2. As shown in FIG.
1, the fiber axis is perpendicular to the cutting direction, and hard copper alloy short fibers 6 having a non-circular cross section are sequentially released from the rake face 7 of the cutter. FIG. 2 emphasizes that the copper alloy short fibers 6 are not connected to each other.

If a curved surface 9 or an uneven surface 9' is formed on the rake surface 7 and/or flank surface 7' of each blade part 31, 31 as shown in FIG. As the surface layer is plastically deformed, the copper alloy short fibers 6', which are not simply linear but have irregular shapes that are curved or bent in whole or in part in the fiber axis direction, are simultaneously removed from a wide area of the copper alloy block 1. Can be created in large numbers in succession. These short fibers have good pull-out resistance and entanglement properties, and this combined with the fact that the free surface is rough over the entire length and has a large surface area makes it suitable for use as a base material for composites, a base material for porous sintered products, and the like.

The copper alloy short fibers 6, 6' are connected to each blade portion 31, 3.
By arbitrarily setting the length l of 1, it is possible to freely manufacture from relatively long to short lengths, and the thickness (cross-sectional area) of copper alloy short fibers 6, 6'
can be adjusted by adjusting the rake angle, feed rate, and cutting speed of the cutting edge 4 within the ranges specified above.

In addition, when using a tool 3 with an inclined blade part 31 (Fig. 3, Fig. 4, Fig. 9, etc.),
The actual turning thickness (A') is fcosα due to the inclination angle α (see Fig. 9), which is formed by the orthogonal line between the cutting surface and the axis of the copper alloy block. The fiber thickness can be reduced, which is advantageous in producing ultra-fine staple fibers.

Next, specific examples of the present invention will be shown.

[Example 1] A free-cutting brass rod with an outer diameter of 60 mm and a length of 200 mm (Cu: 53.78%, Pb: 2.98%, Fe: 0.23%,
Fe+Sn: 0.3%, balance Zn, tensile strength 38.4Kg/
mm ² , elongation 23.6%, reduction of area 25.2%), and a tool with the shape shown in Figure 3 (Material: P class carbide, l: 5 mm, number of blades: 3), and a protrusion length that does not cause chatter. Fixed on the tool post, average cutting speed 86~276m/min, tool feed rate 0.021~
Ultrafine short fibers were produced by the method shown in Figure 1 under the conditions of 0.306 mm/rev and tool rake angle of 10 to -40°.

FIG. 12 shows the influence of turning conditions on short fiber production at this time. In FIG. 12, the desired ultrafine short fibers were obtained in the area surrounded by diagonal lines. The area surrounded by solid lines to the right of each cutting speed display is the fiber generation area.

From the results shown in Fig. 12, as mentioned above, the cutting speed is approximately 86 to 276 m/min, and the tool rake angle is approximately 0.
It can be seen that it is necessary to satisfy the conditions of -40°, feed rate of approximately 0.05 to 0.3 mm/rev, and to have the above-mentioned relationship between cutting speed, tool rake angle, and feed rate.

In other areas, that is, in areas where the rake angle is extremely negative and the feed rate is large, the chips will be serrated, and if the rake angle is large or the feed rate is too small, the chips will be flow-type chips, which will remove the target short fiber. Difficult to generate.

Figure 13 shows the relationship between the cross-sectional area of ultrafine short fibers and manufacturing conditions in the present invention, and shows that the smaller the feed, the smaller the cross-sectional area (in this experiment, the cross-sectional area was up to 0.005 ^mm2) . It can be seen that cutting speed and tool rake angle affect the cross-sectional area in the region where the feed rate is large.

FIG. 14 shows the results of examining the productivity of short fiber production according to the present invention. From this figure, it can be seen that the present invention has extremely high productivity, and that the productivity is highest when the feed is reduced and the cutting speed is increased.

In addition, the present inventors have also experimented with producing copper alloy ultrafine short fibers by cutting methods using flat milling cutters, end mills, etc., but these methods require interrupted processing, so the productivity is significantly lower than that of the present invention. Furthermore, since heavy cutting is performed intermittently due to the rotation of the tool itself, the movement of the tool is complicated, and even if there is a slight deviation in the machine or tool, the manufacturing conditions will immediately change. Therefore, it was not possible to produce ultra-fine staple fibers without any variation. The present invention is a simple method that feeds the copper alloy block in the axial direction or in the direction perpendicular to it without rotating the tool, so there are fewer problems with the accuracy of machines and tools, and there is less variation in cross-sectional area and physical properties. Can produce high quality ultra-fine short fibers.

[Example 2] The same materials and dimensions as in Example 1 were used as the raw materials, and the rectangular throw-away chip shown in Fig. 4 (material: P class carbide, 12.7 mm) was used as the tool.
As shown in Figure 15, the flank surface of the mouth (opening x 4.8 mm) has a lightning-shaped uneven surface (l ₁ : 3 mm, l ₂ : 3 mm, l ₃ : 6.9 mm).
The formed fiber was attached to a holder, and irregularly shaped short fibers were manufactured using the same cutting conditions as in the example.

As a result, as in Example 1, the desired deformed short fibers were produced in each chip in the area shown in FIG. Figures 16a and 16b show the appearance and cross-sectional shape of the short fibers obtained. Note that 7-3 brass, gun metal, and lead bronze castings also showed good results under the above-mentioned manufacturing conditions.

According to the first aspect of the present invention described above, it has characteristics such as high elastic modulus, high abrasion resistance, good electrical and thermal conductivity, and good wettability and sinterability, and is suitable for composite materials and fiber metallurgy. Ultra-fine short fibers suitable for use as base materials are produced extremely efficiently.
Moreover, it can be industrially produced in large quantities with high efficiency by reducing variations in physical properties and cross-sectional area, etc., and the manufacturing process is very simple and there are fewer problems with the accuracy of machines and tools, so raw materials with a low degree of processing are used. This has the advantage of being able to significantly reduce manufacturing costs.

Further, according to the second aspect of the present invention, in addition to the above-mentioned characteristics, an excellent effect can be obtained in that short fibers having good pull-out resistance and entanglement properties can be produced in large quantities extremely efficiently.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing one embodiment of the present invention, FIG. 2 is an enlarged view of the main part thereof, FIG. 2a is a principle explanatory diagram showing the short fiber production mechanism of the present invention, and FIG.
The figure is a side view showing one embodiment of the tool used in the present invention, FIG. 3a is a partially enlarged view thereof, and FIGS. 11a and 11b are perspective views showing the blade part of the tool of the present invention and the obtained short fibers, and FIG. 12 shows appropriate conditions for producing short fibers in the embodiment of the present invention. Graph, Figure 13 is the first
FIG. 2 is a graph showing the relationship between feed and cross-sectional area in the embodiment, FIG. 14 is a graph showing short fiber productivity according to the present invention, FIG. 15 is a plan view showing the tool in the embodiment of the present invention, and FIG. 16 a and b are a perspective view and a cross-sectional view of short fibers obtained by the tool of FIG. 15; DESCRIPTION OF SYMBOLS 1... Copper alloy block, 3... Tool, 6, 6'... Copper alloy short fiber, 7... Rake face, 7'... Flank face, 9...
Curved surface, 9′...uneven surface, 31...blade portion.

Claims (1)

[Claims] 1. In order to obtain short copper alloy fibers, a metal block made of a copper alloy with relatively low ductility such as brass is used as a raw material, and a blade with a length equal to the length of the fiber to be produced is used as a tool. Cutting speed is approximately 86 to 276 m/min, feed rate is approximately 0.05 to approximately
Turning was performed within the range of 0.3 mm/rev and tool rake angle of approx. 0 to -40°, and the feed amount, tool rake angle, and cutting speed were set to the following conditions, and the fiber axis was cut for each cutting edge. A method for producing copper alloy short fibers, which is characterized by creating short fibers having a non-circular cross section that is perpendicular to the direction and each fiber is separated and independent. When the tool rake angle is approximately 0 to -10°, the lower limit of the feed rate is approximately 0.07 to 0.1 in the entire cutting speed range.
mm/rev and the value gradually increases as the tool rake angle becomes more positive. When the tool rake angle is more than about -10° and up to about -20°, the cutting speed should be lower than the upper limit, and the lower limit of the feed rate should be within the range of about 0.05 to 0.07 mm/rev and the tool rake angle is close to positive. The value increases gradually as the cutting speed increases. When the tool rake angle exceeds approximately -20° and reaches approximately -30°, the cutting speed should be approximately 158 m/min or less, and when the cutting speed is at the lower limit, the feed rate should be approximately 0.05 mm/rev or more,
When the cutting speed is approximately 158m/min, the feed rate should be approximately 0.05~
During 0.075mm/rev, the cutting speed is from the lower limit to approx.
Between 158m/min, the feed rate is approximately 0.05mm/rev.
In addition, the upper limit of the feed rate is set to a smaller value as the cutting speed is faster and the tool rake angle is more negative. When the tool rake angle is negative and exceeds approximately -30°, the cutting speed is set to approximately 158 m/min or less, and when the cutting speed is at the lower limit, the feed rate is approximately 0.05 to 0.1 mm/rev, and the cutting speed is approximately 158 m/min. min sets the feed amount to approx.
When the cutting speed is between 0.05 and 0.075 mm/rev and the cutting speed is between the lower limit and about 158 m/min, the feed rate should be adjusted to about 0.05 to 0.1.
Between mm/rev, the faster the cutting speed, the smaller the value. 2. To obtain short copper alloy fibers, a metal block made of a copper alloy with relatively low ductility such as brass is used as a raw material, and as a tool, a plurality of blades with a length equal to the length of the fiber to be produced are formed in a stepped shape. , a cutting speed of approximately 86 to 276 m/min, using a tool arranged in parallel with an uneven shape or a groove and having a curved surface or an uneven surface on the rake face and/or flank surface of each blade part,
Feed rate approx. 0.05~0.3mm/rev, tool rake angle approx. 0~
Turning was carried out within the range of −40° and with the feed rate, tool rake angle, and cutting speed set to the following conditions, so that the fiber axis of each cutting edge was perpendicular to the cutting direction.1
A method for producing copper alloy short fibers, which is characterized by creating short fibers in which each fiber has a separate, independent, non-circular cross section and is curved in the fiber axis direction. When the tool rake angle is approximately 0 to -10°, the lower limit of the feed rate is approximately 0.07 to 0.1 in the entire cutting speed range.
mm/rev and the value gradually increases as the tool rake angle becomes more positive. When the tool rake angle is more than about -10° and up to about -20°, the cutting speed should be lower than the upper limit, and the lower limit of the feed rate should be within the range of about 0.05 to 0.07 mm/rev and the tool rake angle is close to positive. The value increases gradually as the cutting speed increases. When the tool rake angle exceeds approximately -20° and reaches approximately -30°, the cutting speed should be approximately 158 m/min or less, and when the cutting speed is at the lower limit, the feed rate should be approximately 0.05 mm/rev or more,
When the cutting speed is approximately 158m/min, the feed rate should be approximately 0.05~
During 0.075mm/rev, the cutting speed is from the lower limit to approx.
Between 158m/min, the feed rate is approximately 0.05mm/rev.
In addition, the upper limit of the feed rate is set to a smaller value as the cutting speed is faster and the tool rake angle is more negative. When the tool rake angle is more than about -30° and has a large negative value, the cutting speed should be set to about 158 m/min or less, and when the cutting speed is at the lower limit, the feed rate should be set between about 0.05 and 0.1 mm/rev, and the cutting speed should be set to about 158 m/min. min sets the feed amount to approx.
When the cutting speed is between 0.05 and 0.075 mm/rev and the cutting speed is between the lower limit and about 158 m/min, the feed rate should be adjusted to about 0.05 to 0.1.
Between mm/rev, the faster the cutting speed, the smaller the value.