JP6780403B2 - Aggregates of titanium sponge grains, rod-shaped consumable electrodes for melting plasma arcs or melting vacuum arcs and massive briquettes for melting electron beams, and sorting methods and devices for titanium sponge grains. - Google Patents

Description

The present invention relates to an aggregate of titanium sponge particles, particularly an aggregate of titanium sponge particles having excellent shelf suspension resistance, a rod-shaped consumable electrode for plasma arc melting or vacuum arc melting, and an electron beam melting using the same. The present invention relates to a method and an apparatus for sorting bulk briquettes and titanium sponge grains.

Metallic titanium or titanium alloys are widely used not only for aircraft materials but also for consumer heat exchangers, structural materials for buildings, roofing materials, and the like in recent years.

Metallic titanium or titanium alloy is produced by the following steps. First, ilmenite ore (main component ilmenite FeTiO ₃ ) mainly composed of titanium oxide is purified into artificial rutile (purity 85-93% TiO ₂ ) from which iron has been removed by acid leaching or chlorination, and carbon and chlorine gas are obtained. It is converted to titanium tetrachloride TiO ₄ using. Next, this titanium tetrachloride TiO ₄ is distilled many times to produce high-purity titanium tetrachloride TiO ₄ , and the temperature is about 900 to 1000 ° C., for example, by the Kroll method of reducing with magnesium or the Hunter method of reducing with sodium. Sponge-like (spong-like) metallic titanium Ti (sponge titanium) is produced at high temperatures. Currently, most titanium sponges are industrially manufactured by the Kroll process.

Since this sponge titanium is a large lump, it is press-cut into small lumps, crushed and sized to a predetermined size by a shearing device such as a jaw crusher, and the particle size is adjusted to, for example, about 5 to 19 mm by a sieving process. After that, it is shipped as a product (aggregate of titanium sponge grains).

The shipped aggregate of titanium sponge particles is melted by a melting process by vacuum arc remelting (VAR: Vacuum Arc Remelting), plasma arc melting (PAM: Plasma Arc Melting) or electron beam melting (EBM: Electron Beam Melting). It is made of titanium or titanium alloy ingot, and the ingot is further forged, and then rolled or hot extruded according to the application, and processed into forged products, plate-shaped thick plates, thin plates, and other plate materials, rods, and mold materials. And ship it to the user as a product.

In the above-mentioned melting step, for example, in the melting step by electron beam melting, an aggregate of titanium sponge particles, which is a melting raw material, is directly supplied to the electron beam melting furnace via a vibration feeder and a feeder tube. Since the aggregates of titanium sponge particles are supplied via the feeder tube, it is desirable that the particle size of the aggregates of titanium sponge particles is as uniform as possible, and the shape of each titanium sponge particle is also spherical with few irregularities.

In the melting process by vacuum arc melting, plasma arc melting, or some electron beam melting, the rod-shaped consumable electrode or briquette obtained by cold press molding of the aggregate of titanium sponge particles is melted to melt the ingot. To manufacture. Since the rod-shaped consumable electrode or briquette is manufactured by solidifying an aggregate of titanium sponge particles by press molding or the like, it is desirable that the dimensions and shapes of the individual titanium sponge particles constituting the aggregate as a raw material are the same.

Most of the titanium sponge granules of the aggregate produced by the above-mentioned crushing and sizing have a granular outer shape, but since they undergo a mechanical crushing process, some of the aggregates are elongated or flat. Furthermore, there are inevitably those having various shapes such as those having a plurality of protrusions such as a starfish type and a star type (hereinafter, these are collectively referred to as "deformed titanium sponge granules"). The irregularly shaped titanium sponge particles are not sufficiently removed by the sieving process and are inevitably mixed with the aggregate of titanium sponge particles to be shipped.

When such irregularly shaped titanium sponge particles of various shapes are mixed in the aggregate of titanium sponge particles, when the aggregate of titanium sponge particles is supplied to the electron beam melting furnace via the feeder tube, it is in the middle of the feeder tube. A blockage phenomenon (shelf suspension) called clogging, arching or bridging occurs, which hinders the continuous and stable supply of titanium sponge particles to the electron beam melting furnace. Therefore, the operating rate of the electron beam melting furnace is lowered, and the manufacturing cost of titanium or a titanium alloy is increased.

Further, in a vacuum arc melting furnace, a plasma arc melting furnace, or some electron beam melting furnaces, when a rod-shaped consumable electrode or briquette obtained by press-molding an aggregate of titanium sponge particles is melted to produce an ingot, a deformed sponge is produced. When titanium particles are mixed into an aggregate of sponge titanium particles for manufacturing rod-shaped consumable electrodes or briquettes, the uniformity of cold press molding decreases, which causes the rod-shaped consumable electrodes and briquettes to be molded. The strength of the material is reduced, which may lead to breakage.

For this reason, among the aggregates of titanium sponge grains, titanium sponge grains in which non-metallic foreign substances are accidentally mixed in during the manufacturing process, titanium sponge grains that have been discolored due to oxidation reaction or nitriding reaction in the manufacturing process, and irregularly shaped titanium sponge. Grains are sorted and removed to some extent by visual inspection or machine in advance before shipping.

Visual sorting is currently performed by the operator monitoring the titanium sponge grains moving at a constant speed on the belt conveyor. Titanium sponge particles mixed with non-metallic foreign matter and titanium sponge particles that have discolored are relatively easy to monitor, but irregularly shaped titanium sponge particles cannot be accurately sorted without three-dimensional observation, and can be visually checked by the operator. Sorting by is inherently difficult.

Further, since the worker cannot perform such a sorting work for a long time, several workers often perform the sorting work at the same time. However, the sorting work may be overlooked, and the sorting work by several people may cause a difference in the level of the sorting work. Furthermore, since it is impossible for the same worker to always engage in visual sorting work, a shift system must be introduced in which workers are sequentially replaced, but there is a difference in the level of sorting work between shifts. May occur.

Therefore, it is not possible to visually select and remove irregularly shaped titanium sponge particles having various shapes.

In Patent Document 1, light is projected onto the transferred titanium sponge grains from a plurality of directions, wavelengths of red, green, and blue are extracted from the reflected light from the titanium sponge grains, and these are numerically converted into electrical signals, and these are used. A method for detecting a foreign substance contained in titanium sponge particles is disclosed by comparing with a reference value of a non-defective product.

Patent Document 2 includes a sponge titanium grain delivery portion and an opening provided in the middle of the delivery portion, and the cross-sectional shape of the delivery portion orthogonal to the delivery direction of the sponge titanium grains is corrugated or W-shaped. A sponge titanium grain sorting device in which an opening is formed in a direction orthogonal to the extending direction of the valley in a corrugated or W type, or in a direction along the extending direction of the valley in the valley. Is disclosed. It is said that this sorting device can efficiently sort and remove irregularly shaped titanium sponge particles mixed in titanium sponge grains.

Japanese Unexamined Patent Publication No. 63-157044 Japanese Unexamined Patent Publication No. 2014-166602

In the method disclosed in Patent Document 1, although it is certainly possible to detect, sort and remove foreign substances other than colored sponge titanium particles and sponge titanium particles, irregular sponge titanium particles having various shapes are detected. You can't.

Although the sorting apparatus disclosed in Patent Document 2 can sort out long deformed titanium sponge grains, it cannot sort and remove deformed titanium sponge grains having various shapes other than long shape. Can not.

In general, research and development on powder or granular material has been carried out for a long time in the industry dealing with powder, and many techniques for classifying and sorting powder or granular material are known. Classification / sorting methods include dry classification, wet classification, counting method, etc. (see "Reference: Powder" Theory and Application ", p. 455, Table 6-3").

For example, sieving and centrifugation are known as dry classification, but since centrifugation mainly targets powders and granules of about 200 to 50 μm, it is applicable as a method of selecting titanium sponge particles having a particle size of about 5 to 19 mm. Can not. Further, in the wet separation method, it is difficult to apply to titanium sponge particles because it is necessary to bring the powder or granular material into contact with the liquid. As described above, the conventionally known classification / sorting technique for powder or granular materials cannot be directly used for sorting titanium sponge grains.

In particular, in order to select irregularly shaped titanium sponge grains having various shapes,
(I) Obtaining the shape of titanium sponge grains (individual recognition),
It is necessary to (II) extract the specificity of the shape of the acquired titanium sponge grains and perform a discrimination calculation, and (III) to sort the titanium sponge grains based on the result of the discrimination calculation.

However, the suspension resistance (fluidity) of titanium sponge grains is the physical properties (shape, dimensions, particle size, mass, density, fine irregularities on the surface, chemical composition of the surface) and environmental conditions (temperature, temperature,) of the titanium sponge grains. Humidity). For this reason, it is important how to determine the liquidity evaluation index.

The dimensions and mass of titanium sponge grains are relatively easy to grasp. For example, the dimensions of titanium sponge grains can be narrowed down to some extent by using the conventional sieving method, and the mass of titanium sponge grains can be automatically reduced by applying general-purpose sorting technology based on individual mass. Can be processed.

On the other hand, in order to obtain the density of titanium sponge particles, it is necessary to accurately grasp the shape of the powder or granular material. The "bulk density", which is often used in quality control of powders and granules, is extremely sensitive and can be easily used as an index of particle shape if the same substance has the same particle size. However, it cannot be used for sorting irregularly shaped titanium sponge grains.

The particle size and shape of the powder or granular material are the most important characteristic values among the various physical properties of the powder or granular material, and many studies have been conducted so far and they have been established as standards. However, since the shape of the powder or granular material varies and is suitable depending on the use of the powder or granular material, it is not easy to extract the specificity of the shape. Some of them are shown below.

[Equivalent diameter of sphere] This is a method of reducing to a sphere that is the easiest to handle both geometrically and physically. The equivalent volume sphere diameter uses the diameter of a sphere having the same volume as the powder granule, and the equal surface area sphere equivalent diameter uses the diameter of the sphere having the same surface area as the powder granule.

[Triaxial diameter] The triaxial diameter is a method of defining the dimensions of a rectangular parallelepiped (outer tangent rectangular parallelepiped) having the minimum volume in which one particle is exactly accommodated by the length L, width B, and thickness T of the particles. It is ideal for measuring the shape of powder or granular material, but the measurement is complicated.

[Projection diameter] This is a method of arranging powder or granular materials on a plane substrate and observing the appearance of the powder or granular material from a certain direction (for example, from directly above). Projection of the powder or granular material by an optical microscope, an electron microscope, or photography. After obtaining the figure, calculate the parameters (projected particle size) listed below (for example, see Shigeo Miwa: "General Theory of Powder Engineering", 1981, Nikkan Kogyo Shimbun).

1 (a) to 1 (d) are explanatory views showing various methods for calculating projected particle diameters.

(A) Feret diameter As shown in Fig. 1 (a), the size of the sample is continuously measured while moving the sample (powder and granular material) randomly arranged on the plane substrate in a certain direction (for example, the arrow direction) with a fine movement device. Measure or measure the dimensions while moving a magnified projection or magnified photograph of those particles in one direction. In principle, it is suitable for measuring convex-shaped powders and granules, but errors occur in powders and granules containing concave parts such as irregularly shaped sponge titanium particles. Also, the information is limited to information regarding a certain direction of the powder or granular material.

(B) Martin diameter As shown in FIG. 1 (b), the length of the line segment that bisects the projected area of the powder or granular material in a certain direction is used. However, it is not possible to obtain information on the uneven portion of the irregularly shaped titanium sponge grains in the projected area.

(C) Maximum diameter in a fixed direction As shown in FIG. 1 (c), a portion having a maximum width is measured in a fixed direction. In principle, it is suitable for measuring powder or granular material having a convex portion shape, but an error occurs in a deformed sponge titanium granule containing a concave portion. Also, the information is limited to information regarding a certain direction of the powder or granular material.

(D) Equivalent diameter of projected circle As shown in FIG. 1 (d), the diameter of a circle equal to the projected area of the powder or granular material is used. If the powder or granular material is convex and the arrangement of the powder or granular material is random, the surface area of the powder or granular material is equal to four times the average projected area of the powder or granular material. However, the projected area does not include information on the uneven portion of the irregularly shaped titanium sponge grains. Therefore, it is not possible to obtain information on the anisotropy of the powder or granular material.

(E) Equivalent circumference circle equivalent diameter Use the diameter of a circle having a circumference equal to the circumference of the projected figure of the powder particles. In principle, it is not possible to distinguish the uneven portion of the deformed sponge titanium grains.

In this way, many evaluation criteria regarding the particle size and shape of powder or granular material have been known so far, but irregular titanium sponge grains that cause a blockage phenomenon (shelf suspension) due to having various shapes are identified. The evaluation method that can be performed has not been known so far. For this reason, a deformed shape that causes shelving contained in an aggregate of titanium sponge particles obtained by press-cutting a large mass of titanium sponge and further crushing and sizing the small mass to a size of about 5 to 19 mm. By efficiently selecting and removing titanium sponge particles, an aggregate of titanium sponge particles having a predetermined size and shape and, as a result, excellent in shelf suspension resistance (fluidity) is desired.

The present invention has been made in view of this problem of the prior art, and the sponge obtained by press-cutting a large mass of titanium sponge and further crushing and sizing the small mass to a size of about 5 to 19 mm. It is an aggregate of titanium grains, has excellent shelf suspension resistance (for example, it is difficult for shelf suspension to occur during grain transportation), and is molded during the production of rod-shaped consumable electrodes or briquettes after press molding, which is a post-process. An aggregate of titanium sponge particles with excellent properties (for example, high density after molding, high bending force of press molding material, and relatively small processing force required for press molding), and a plasma arc made from this. It is an object of the present invention to provide a rod-shaped consumable electrode for melting or vacuum arc melting, a massive briquette for melting an electron beam, and a method and an apparatus for sorting titanium sponge particles.

As a result of diligent studies to solve the above problems, the present inventor has obtained the findings A and B listed below and completed the present invention.

(A) The suspension resistance of the aggregate of titanium sponge grains is the projected area obtained by projecting the titanium sponge grains crushed and sized to a size of about 5 to 19 mm from above along the normal line of the plane base. and Ap (mm ^2), a convex ratio is the area Ach of convex hull calculated from the projected shape ratio of ^{(mm 2) (Ap / Ach} ), is calculated from the shape which is projected on a plane base projection Two shape parameters, the circularity of Wadell, which is the ratio (Lr / Lp) of the length Lp (mm) of the peripheral edge of the figure and the length Lr (mm) of the circumference of a circle having an area equal to the projected area Ap. Strongly correlates with.

(B) An aggregate of titanium sponge particles having a convex ratio of 0.84 or more and a Wadell circularity of 0.55 or more has excellent shelf suspension resistance and can achieve the above object.

The present invention is as listed below.

(1) Obtained by projecting titanium sponge grains crushed and sized to a size of about 5 to 19 mm placed on a horizontally arranged flat base from above along the normal line of the flat base. The convex ratio, which is the ratio (Ap / Ach) of the projected area Ap (mm ² ) to the convex package area Ach (mm ² ) calculated from the projected shape, is 0.84 or more, and the plane substrate The ratio (Lr / Lp) of the length Lp (mm) of the peripheral edge of the projected figure calculated from the shape projected above and the length Lr (mm) of the circumference of a circle having an area equal to the projected area Ap. ) Is an aggregate of titanium sponge grains having a circularity of 0.55 or more.

(2) A rod-shaped consumable electrode for plasma arc dissolution or vacuum arc dissolution, which is made of the aggregate of titanium sponge particles described in item 1.

(3) A massive briquette for melting an electron beam, which is made of the aggregate of titanium sponge particles described in item 1.

(4) For example, from an aggregate of titanium sponge granules obtained by further crushing and sizing a large mass of titanium sponge produced by the Kroll process to a size of about 5 to 19 mm. , A method of selecting titanium sponge grains for producing titanium metal or titanium alloy ingots that are melted in a plasma arc melting furnace, electron beam melting furnace or vacuum arc melting furnace.
The crushed and sized titanium sponge particles are placed on a flat substrate,
The ratio (Ap / Ach) of the projected area Ap (mm ² ) obtained by projecting from above along the normal line of the plane base and the area Ach (mm ² ) of the convex packet calculated from the projected shape. A circle having a convexity ratio of 0.84 or more and having an area equal to the projected area Ap and the length Lp (mm) of the peripheral edge of the projected figure calculated from the shape projected on the plane base. A method for selecting sponge titanium grains, which sorts sponge titanium grains having a Wadell circularity of 0.55 or more, which is a ratio (Lr / Lp) to the circumference length Lr (mm).

(5) For example, plasma arc melting is performed from an aggregate of titanium sponge particles obtained by press-cutting a large mass of titanium sponge produced by the Kroll process and further crushing and sizing the small mass to a size of about 5 to 19 mm. A device that sorts titanium sponge grains for producing titanium metal or titanium alloy ingots that are melted in a furnace, electron beam melting furnace, or vacuum arc melting furnace.
A mounting means for mounting the crushed and sized titanium sponge grains on a flat surface substrate,
The ratio of the projected area Ap (mm ² ) obtained by projecting from above along the normal line of the plane base of the sponge titanium grains to the convex package area Ach (mm ² ) calculated from the projected shape. A circle having an area equal to the projected area Ap and the convex ratio of (Ap / Ach) and the length Lp (mm) of the peripheral edge of the projected figure calculated from the shape projected on the plane base. A measuring means for measuring the circularity of Wadell, which is the ratio (Lr / Lp) to the length of the circumference Lr (mm),
A sorting device for titanium sponge grains, comprising a sorting means for sorting titanium sponge grains having a convex ratio (Ap / Ach) of 0.84 or more and a circularity of Wadell of 0.55 or more.

According to the present invention, for example, an aggregate of titanium sponge particles obtained by press-cutting a large mass of titanium sponge produced by a Kroll process and further crushing and sizing the small mass to a predetermined size, which is suspended on a shelf. In addition to being excellent in property (fluidity), it is also excellent in formability during the production of rod-shaped consumable electrodes of plasma arc melting furnaces or vacuum arc melting furnaces by cold press molding, which is a subsequent process, or massive briquettes for electron beam melting. An aggregate of titanium sponge grains can be provided.

Specifically, according to the present invention, it is possible to manufacture a rod-shaped consumable electrode or a lump briquette having a high density and a high bending force while being less likely to be suspended during transportation, and the processing force required for press molding is relatively small. An aggregate of titanium sponge grains can be provided.

Therefore, according to the present invention, a rod-shaped consumable electrode for plasma arc melting or vacuum arc melting, a massive briquette for electron beam melting, and a method for selecting titanium sponge particles using the aggregate of titanium sponge as a material. And a sorting device can be provided.

1 (a) to 1 (d) are explanatory views showing various methods for calculating projected particle diameters. FIG. 2 is an explanatory diagram of the convexity ratio. FIG. 3 is an explanatory diagram of Waddell's circularity. FIG. 4 is a graph showing the results of calculating and classifying the convexity ratio and Waddell's circularity using a model figure. FIG. 5 is an explanatory diagram conceptually showing the mounting means. FIG. 6 is a flow chart showing an example of control of the sponge titanium grain sorting device according to the present invention. FIG. 7 is a graph showing the measurement results of the distribution of the shape parameters of the titanium sponge grains. FIG. 8 is an explanatory view showing a shelf suspension resistance (fluidity) test apparatus.

The present invention will be described.

1. 1. Aggregation of Titanium Sponge Granules According to the Present Invention The aggregate of titanium sponge granules according to the present invention has a convex ratio of 0.84 or more as defined below and a Wadell circularity of 0.55 as defined below. That is all.

Convex ratio: Obtained by projecting titanium sponge grains crushed and sized to a size of about 5 to 19 mm placed on a horizontally arranged flat base from above along the normal of the flat base. Ratio (Ap / Ach) of the projected area Ap (mm ² ) to be projected and the convex hull area Ach (mm ² ) calculated from the projected shape.
Wadell's circularity: The length Lp (mm) of the peripheral edge of the projected figure calculated from the shape projected on the horizontally arranged plane base, and the length of the circumference of a circle having an area equal to the projected area Ap. Ratio with Lr (mm) (Lr / Lp)
The reason for defining the convexity ratio and Waddell's circularity in this way will be described. First, the present inventor conducted a shelf suspension resistance (fluidity) test many times using an aggregate of titanium sponge particles, and investigated the shape of the deformed titanium sponge particles that cause shelf suspension (occlusion phenomenon). As a result, the suspension resistance of the aggregate of titanium sponge particles strongly correlates with the two shape parameters of the convexity ratio (Ap / Ach) (convexity ratio) and the circularity (Lr / Lp) of Wadell. It has been found.

FIG. 2 is an explanatory diagram of the convexity ratio. AKH Kwan and CF Mora: "Effects of various shape parameters on packing of aggregate particles", Magazine of Concrete Research, 2001, 53, No. 2, April, P91-100 It is described in.

In addition, FIG. 3 is an explanatory diagram of Waddell's degree of circularity, which is a diagram of the contents described in Shigeo Miwa: "General Theory of Powder Engineering", 1981, Nikkan Kogyo Shimbun. Is.

The graph of FIG. 4 shows the results of calculating and classifying the convexity ratio (Ap / Ach) and Wadell's circularity (Lr / Lp) using the model figure.

As shown in the graph of FIG. 4, the convexity ratio (Ap / Ach) becomes large in a shape having few surface irregularities. The convexity ratio (Ap / Ach) is close to 1 for circles, squares, rectangles, and triangles. On the other hand, the convex ratio (Ap / Ach) is small in shapes that include many recesses, such as cruciforms, starfish, and stars. That is, if there are many uneven portions in the deformed titanium sponge grains, the deformed sponge titanium is likely to be entangled with other sponge titanium grains during flow from these, and the suspension resistance (fluidity) of the aggregate of the sponge titanium grains is suspended. ) Decreases.

Further, as shown in the graph of FIG. 4, when the circularity (Lr / Lp) of Waddell becomes small, the depth of the unevenness becomes large, or the depth of the unevenness is not large but the number of unevenness increases. As Wadell's circularity (Lr / Lp) increases, the surface becomes smoother and closer to a circle. That is, when the shape of the irregularly shaped titanium sponge particles deviates from the circular shape, the suspension resistance (fluidity) of the aggregate of the titanium sponge particles decreases.

From the graph of FIG. 4, there is a tendency that these two shape parameters (Ap / Ach) and (Lr / Lp) approach a perfect circle when their values approach 1, but they always have a clear correlation. Each is a parameter that indicates the peculiarity of the figure, and by using both of them, it is possible to improve the sorting accuracy of the irregularly shaped sponge titanium grains that cause shelf suspension.

Specifically, an aggregate of titanium sponge grains having a convex ratio (Ap / Ach) of 0.84 or more and a Wadell circularity (Lr / Lp) of 0.55 or more has a shelf suspension resistance. Excellent in fluidity (for example, shelving is unlikely to occur during grain transportation), and excellent in moldability during cold rolling of rod-shaped consumable electrodes or massive briquettes after press molding, which is a post-process. ..

2. The rod-shaped consumable electrode for melting a plasma arc or a vacuum arc according to the present invention and the massive briquette for melting an electron beam according to the present invention are manufactured by, for example, an aggregate of titanium sponge particles according to the present invention. It is an aggregate of titanium sponge particles obtained by press-cutting a large mass of titanium sponge and further crushing and sizing the small mass to a size of about 5 to 19 mm, and has the above-mentioned convex ratio (Ap / Ach) and Since it has Wadell's circularity (Lr / Lp), the dimensions and shape of the titanium sponge grains are more uniform than before.

Therefore, when a rod-shaped consumable electrode for plasma arc melting or vacuum arc melting or a massive briquette for electron beam melting is manufactured by cold rolling using an aggregate of titanium sponge particles according to the present invention as a raw material, It is said that excellent formability during rolling of a rod-shaped consumable electrode or a lump briquette, for example, a rod-shaped consumable electrode or a lump briquette having a high density and a bending resistance can be produced, and the processing force required for press molding is relatively small. You can get the effect.

3. 3. Sorting device and sorting method for titanium sponge grains according to the present invention In the sorting device for titanium sponge grains according to the present invention, for example, a large block of titanium sponge produced by a Kroll process is press-cut to obtain 5 small blocks. An ingot of metallic titanium or a titanium alloy is produced by melting in a plasma arc melting furnace, an electron beam melting furnace or a vacuum arc melting furnace from an aggregate of titanium sponge particles obtained by crushing and sizing to a size of about 19 mm. It is a device for sorting titanium sponge grains for this purpose.

The sorting device according to the present invention includes a mounting means, a measuring means, and a sorting means.

The mounting means has a function of placing crushed and sized titanium sponge grains on a flat substrate without significance. The mounting means is not limited to a specific means, and any powder or granule having the same size and mass as the titanium sponge granules may be placed.

FIG. 5 is an explanatory diagram conceptually showing the mounting means. As shown in the figure, as the mounting means, for example, a hopper type in which the titanium sponge particles are intermittently freely dropped from above on the belt conveyor, or a downward ejection means in which the titanium sponge particles are ejected onto the belt conveyor from below. The type is illustrated.

The measuring means has a function of measuring the convex ratio (Ap / Ach) of the individual titanium sponge grains constituting the aggregate of titanium sponge grains and the circularity (Lr / Lp) of Wadell. Any measuring means can be used as long as the convex ratio (Ap / Ach) of the titanium sponge grains and the circularity (Lr / Lp) of Wadell can be measured. For example, the titanium sponge grains placed on a flat substrate. An example is a combination of a digital camera that captures a photograph and creates a projected figure, and an image processing means that processes the captured image.

The sorting means is based on the convexity ratio (Ap / Ach) of each sponge titanium grain measured by the measuring means and the circularity (Lr / Lp) of Wadell, and the convexity ratio (Ap / Ach): 0.84 or more. Sponge titanium grains satisfying Wadell's circularity (Lr / Lp): 0.55 or more are selected, and convex ratio (Ap / Ach): 0.84 or more and Wadell's circularity (Lr / Lp). : Has a function of removing sponge titanium particles that do not satisfy 0.55 or more. The sorting means may be any means having this function, and is not limited to a specific means.

As the sorting means, for example, the sensor incorporated in the measuring means detects the titanium sponge particles flowing one after another on the belt conveyor, and the measuring means individually recognizes each titanium sponge grain individually. After measuring them, the measuring means calculates Wadell's circularity (Lr / Lp) and convexity ratio (Ap / Ach), and a predetermined discriminant, for example, convexity ratio (Ap / Ach) ≥ 0.84. In addition, pass or fail is determined according to Wadell's circularity (Lr / Lp) ≥ 0.55.

The sorting means receives the result, and the titanium sponge grains that are passed are allowed to flow on the belt conveyor as they are, and the titanium sponge grains that are rejected operate the sorting spatula installed next to the belt conveyor. It has a function of ejecting a rejected sponge from the conveyor, which is exemplified.

FIG. 6 is a flow chart showing an example of control of the sponge titanium grain sorting device according to the present invention.

As shown in FIG. 6, the measuring means includes a front sensor unit, a photographing unit, an image analysis / discrimination unit, and a rear sensor unit.

First, the front sensor unit distinguishes particles moving on the belt conveyor, tracks the movement of individual particles, assigns identification numbers to the particles, and performs individual recognition. Next, the front sensor unit sets the shooting timing according to the moving speed.

The shooting unit sets the shutter speed and exposure to obtain a clear image from the camera settings, that is, the moving speed of particles and the brightness at the shooting location. The photographing unit photographs the particles numbered by the identification number by, for example, a digital camera device according to the photographing timing.

The image analysis / discrimination unit performs image analysis on the captured image using image processing software, discriminates pass / fail by a preset discriminant, and codes the result to the identification number.

Further, the rear sensor unit distinguishes and tracks moving particles, and sends the particle identification number and the pass / fail code to the sorting means.

Next, the classification unit, which is an element of the sorting means, is based on the convexity ratio (Ap / Ach) of the individual sponge titanium grains and the circularity (Lr / Lp) of Wadell obtained from the measuring means. Sponge titanium grains satisfying (Ap / Ach): 0.84 or more and Wadell's circularity (Lr / Lp): 0.55 or more were selected, and the convex ratio (Ap / Ach): 0.84 or more, And Wadell's circularity (Lr / Lp): Removes sponge titanium grains that do not satisfy 0.55 or more.

Next, a sorting method according to the present invention for sorting sponge titanium grains using this sorting device will be described.

In the sorting method according to the present invention, as described above, for example, the small lumps obtained by press-cutting a large lump of titanium sponge produced by the Kroll process are further crushed and sized to a size of about 5 to 19 mm. This is a method for selecting titanium sponge grains for producing an ingot of metallic titanium or a titanium alloy, which is melted in a plasma arc melting furnace, an electron beam melting furnace or a vacuum arc melting furnace from the obtained aggregate of titanium sponge grains. ..

First, the crushed and sized titanium sponge grains are placed on a flat substrate by a placing means.

The convex ratio (Ap / Ach) of the titanium sponge grains and the circularity (Lr / Lp) of Wadell are measured for each titanium sponge grain by the measuring means.

By the sorting means, sponge titanium grains satisfying the convexity ratio (Ap / Ach): 0.84 or more and the circularity (Lr / Lp) of Wadell: 0.55 or more are selected, and the convexity ratio (Ap / Ap / Ach): Removes sponge titanium particles that do not satisfy Wadell's circularity (Lr / Lp): 0.55 or more and 0.84 or more.

Next, the results of the investigation using an actual aggregate of titanium sponge particles will be described.

First, an aggregate of titanium sponge granules made of normal grade industrial pure titanium under a sieve (1 inch under) having a size of 1 inch and whose typical chemical composition is shown in Table 1 was prepared. Since it contains a wide range of titanium sponge particles as it is, it is classified using a sieve with a mesh size of 4.75 and 19.0 mm to remove fine titanium sponge particles, and the size of the aggregate of titanium sponge particles is increased to +4.75. Aligned to ~ -19.0 mm. If a normal-grade sponge of 1 inch under is used as it is, fine grains may be mixed, and they may enter the gaps of relatively large grains, increase the fluidity, and it is difficult to grasp the influence of the shape of the grains. ..

From this, 1000 titanium sponge grains were arbitrarily taken out to form an aggregate of titanium sponge grains, and the convex ratio (Ap / Ach) of each titanium sponge grain and the circularity of Wadell (Lr / Lp) were determined.

Specifically, one titanium sponge grain was placed on a horizontally installed flat base, and a projected figure was created by photographing with a digital camera from a position 60 mm above the normal of the flat base. The background was white on the flat board, and the number of shooting pixels was 2448pixelx3264pixel, which was saved in Tif format. The saved image was subjected to the image processing of the following steps (i) to (vi) using commercially available image processing software (Mathematica, Image J).

(I) Binarize.

(Ii) Obtain the projected area Ap (number of pixels) occupied by the titanium sponge grains.

(Iii) The convex hull of titanium sponge grains is obtained, and the area Ach (number of pixels) included in the convex hull is obtained.

(Iv) Obtain the convex ratio (Ap / Ach) of titanium sponge grains.

(V) The total of the line segments connecting the center points of the rectangular polygons of the pixels corresponding to the peripheral portion of the image of the titanium sponge grain, that is, the length Lp of the peripheral portion is obtained.

(Vi) The circularity (Lr / Lp) of Wadell is determined by using the length Lr of the circumference of a circle having an area equal to the projected area Ap.

Ask as.

The measurement results are shown in the graph of FIG. The graph of FIG. 7 shows the distribution of the shape parameters of the titanium sponge grains, the horizontal axis showing the convexity ratio (Ap / Ach), and the vertical axis showing the circularity (Lr / Lp) of Waddell.

As shown in the graph of FIG. 7, the convex ratio (Ap / Ach) of the aggregate of about 1000 titanium sponge grains is distributed from 0.417 to 0.999, and the circularity (Lr / Lp) of Wadell is 0.096 to 0.947. It was distributed.

Next, in order to investigate the shelf suspension resistance (fluidity) of the aggregate of titanium sponge particles, the shelf suspension resistance (fluidity) test apparatus shown in FIG. 8 was created. This shelf-suspension test device uses transparent acrylic circular pipes (between parts A and B and between parts C and D) and funnel-shaped pipes (between parts B and C). It was created by aligning the centers of each and connecting them. FIG. 8 shows a state of being cut by a plane including the center line, and the entire cross-sectional shape is a semicircle. All the dimensions in FIG. 8 are internal methods. The flat surface including the center line can be attached and detached by attaching a cover of a transparent acrylic plate, and the shelf suspension resistance (fluidity) of the aggregate of titanium sponge grains can be observed. Further, it has a structure in which the acrylic plate can be removed to take out the titanium sponge particles.

The above-mentioned aggregate of titanium sponge particles is poured from above the shelf-suspendability (fluidity) test device and accommodated, and the aggregate of sponge particles is opened by opening the lid attached to the lowermost portion (part D). I let it fall freely. This operation was repeated many times, and shelving (blocking phenomenon) was generated 77 times in the vicinity of the C portion.

Every time shelving occurred, the cover of the transparent acrylic plate was removed, and the surrounding sponge titanium particles causing shelving (blocking phenomenon) were taken out. The location of shelving is clearly visible from its shape, as it is called arching or bridging. Here, attention is paid to the lowermost surface of the bridging portion (bridging portion) of the portion where the particles are blocked, and the particles causing the blockage are limited to the first layer of the particles lined up on the lowermost surface. It was limited to 3 particles in the radial radial direction from the center line in the C part. The shape parameters of these particles (convex ratio (Ap / Ach) and Waddell's circularity (Lr / Lp)) were investigated.

As a result, there were no titanium sponge grains having a convexity ratio (Ap / Ach) of 0.84 or more and Wadell's circularity (Lr / Lp) of 0.55 or more in the hanging portion.

Using the shelf suspension resistance (fluidity) test apparatus shown in FIG. 8, the fluidity of the aggregate of titanium sponge particles as delivered was tested. First, using a sorting device, the aggregates of titanium sponge were classified according to the convexity ratio and the circularity of Wadell as described below, and were sorted so that about 1000 titanium sponge grains could be obtained in each classification.
Classification 1: 0.417 ≤ Ap / Ach ≤ 0.999 0.096 ≤ Lr / Lp ≤ 0.947
Category 2: 0.84 ≤ Ap / Ach ≤ 0.999 0.55 ≤ Lr / Lp ≤ 0.947
Classification 3: 0.84 ≤ Ap / Ach ≤ 0.999 Lr / Lp <0.54
Category 4: Ap / Ach <0.83 0.55 ≤ Lr / Lp ≤ 0.947
Category 5: Ap / Ach <0.83 Lr / Lp <0.54
Next, for each of the categories 1 to 5, the shelf suspension test was performed 120 times with the shelf suspension resistance (fluidity) test device, and the occurrence rate of shelf suspension was calculated. The results are shown in Table 2.

As shown in Table 2, when the test was conducted in the state of receiving (Category 1), the occurrence rate of hanging on the shelf was about 64%.

On the other hand, in the example (classification 2) in which the convexity ratio (Ap / Ach) and the circularity of Waddell (Lr / Lp) were within the scope of the present invention, shelving did not occur.

Further, the shelving occurrence rate of Comparative Examples 2 to 4 (Category 3 to 5) was about 27 to 100%. The shelving occurrence rate of 27% seems to be a good number at first glance, but if shelving occurs during the actual melting of titanium sponge under vacuum, if it is mild, the feeder is vibrated by the vibration device attached to it. It may be possible to eliminate the suspension, but if it still does not, break the vacuum of the melting furnace to open the furnace to the atmosphere, and the operator enters the furnace and applies a tool to the blocked part of the feeder to eliminate the blockage. Will be done.

This work takes a long time and significantly reduces productivity. In addition, since it is a device that melts in a vacuum, if it is exposed to the atmosphere for a long time, it will cause rust on the structure inside the furnace, which will have an adverse effect on quality by lowering the degree of vacuum during the subsequent melting work. .. Therefore, it is necessary to eliminate the shelving phenomenon, and the significance of the present invention is extremely large.

Claims (5)

An aggregate of the size of the particle size 5~19mm integer grain sponge titanium particles,
The sponge titanium grains are calculated from the projected area Ap (mm ² ) obtained by projecting from above along the normal line of the planar substrate when placed on the horizontally arranged planar substrate, and the projected shape. The convex ratio, which is the ratio (Ap / Ach) to the area Ach (mm ² ) of the convex package, is 0.84 or more, and the peripheral edge of the projected figure calculated from the shape projected on the plane substrate. The circularity of Wadell, which is the ratio (Lr / Lp) of the length Lp (mm) of the circle to the circumference length Lr (mm) of a circle having an area equal to the projected area Ap, is 0.55 or more. , An aggregate of titanium sponge grains. A rod-shaped consumable electrode for plasma arc dissolution or vacuum arc dissolution, which is made of the aggregate of titanium sponge particles according to claim 1. A massive briquette for melting an electron beam, which is made of the aggregate of titanium sponge particles according to claim 1. Nodules obtained a large mass of titanium sponge by pressing cut, from the size to an integer grain-obtained titanium sponge particles in an aggregate particle size 5～19M m by sieving processes, plasma arc melting furnace, A method of selecting titanium sponge grains for producing ingots of metallic titanium or titanium alloys that are melted in an electron beam melting furnace or a vacuum arc melting furnace.
The crushed and sized titanium sponge particles are placed on a flat substrate,
The ratio (Ap / Ach) of the projected area Ap (mm ² ) obtained by projecting from above along the normal line of the plane base and the area Ach (mm ² ) of the convex packet calculated from the projected shape. A circle having a convexity ratio of 0.84 or more and having an area equal to the projected area Ap and the length Lp (mm) of the peripheral edge of the projected figure calculated from the shape projected on the plane base. A method for selecting sponge titanium grains, which sorts sponge titanium grains having a Wadell circularity of 0.55 or more, which is a ratio (Lr / Lp) to the circumference length Lr (mm). Nodules obtained a large mass of titanium sponge by pressing cut, of an aggregate of size to an integer grain sponge titanium having a grain size of 5～19M m by sieving processes, plasma arc melting furnace, an electron beam melting furnace Or a device that sorts titanium sponge grains for producing ingots of metallic titanium or titanium alloys that are melted in a vacuum arc melting furnace.
A mounting means for mounting the crushed and sized titanium sponge grains on a flat surface substrate,
The ratio of the projected area Ap (mm ² ) obtained by projecting from above along the normal line of the plane base of the sponge titanium grains to the convex package area Ach (mm ² ) calculated from the projected shape. A circle having an area equal to the projected area Ap and the convex ratio of (Ap / Ach) and the length Lp (mm) of the peripheral edge of the projected figure calculated from the shape projected on the plane base. A measuring means for measuring the circularity of Wadell, which is the ratio (Lr / Lp) to the length of the circumference Lr (mm),
Titanium sponge grains provided with a sorting means for selecting titanium sponge grains having a convex ratio (Ap / Ach) of 0.84 or more and a circularity (Lr / Lp) of Wadell of 0.55 or more. Sorting device.