JP2000015523A - Wire guide member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an anti-wear properly by forming at least a contact part with a wire by an aluminous sintered body containing the specific weight % of Al2O3, and the specific weight % of Ti in terms of TiO2 and dispersing an oxide particle containing Ti into the grain and grain boundary of an alumina crystal layer. SOLUTION: In a guide roller 2, nozzle 3, electrified terminal 4, article to be machined 5 and rollers 6, 7 as a wire guide member, the contact part with a wire 1 is composed of an aluminous sintered body containing 60-99 weight % of AL2O3 and 0.2-5 weight % of Ti in terms of TiO2. On its surface, an oxide particle containing Ti is educed and dispersed in an alumina crystal grain and across its grain boundary. Thereby, a residual stress is formed in a semi-grain boundary and minute area and a hardness is extremely increased and the wear by degraining can be restrained effectively and consequently, the anti-wear property and anti-chipping property are extremely improved and a long life is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a guide roller for guiding a wire in a wire electric discharge machine, and a wire guide member such as an energizing terminal.

[0002]

2. Description of the Related Art In a wire electric discharge machine, a wire is used as an electrode, and a voltage is applied between the wire and a workpiece to cause a discharge phenomenon. This is to perform shape processing.

[0003] The members that come into contact with the wire include a guide roller, a nozzle, a current-carrying member, and the like. Such a wire guide member is required to have abrasion resistance in order to slide with the wire. Used. In addition, in the case of a guide roller or a nozzle, since it slides on a wire to which a voltage of 150 V or more is applied, insulation is also required.

[0004] In response to such demands, it has been proposed that the ceramics be composed of ceramics containing alumina, zirconia, silicon nitride or the like as a main component, and silicon nitride ceramics are particularly desirable (Japanese Patent Application Laid-Open Nos. 17
3819, JP-A-62-84928, and JP-B-5-3.
0569).

[0005]

However, when a metal mold for punching is to be machined with high precision using a wire electric discharge machine, the conventional wire having a diameter of about 0.8 to 0.2 mm cannot cope with the problem. Therefore, a very thin wire having a diameter of about several tens of μm must be used. And with such a reduction in diameter,
The wear of the guide member has been accelerated, and even the wire guide member made of silicon nitride ceramics has been replaced after being used for about one week, and the frequency of replacement has become a problem.

SUMMARY OF THE INVENTION Accordingly, the present invention has been completed in view of the above circumstances, and an object of the present invention is to provide a wire guide member with further improved wear resistance and reduced production cost.

[0007]

According to the wire guide member of the present invention, at least the contact portion with the wire is made of Al ₂ O ₃ 60-9.
9 wt%, in terms of Ti to TiO ₂ 0.2 to 5 wt%
And oxide particles containing Ti are dispersed within the grains of the alumina crystal phase and in the grain boundaries.

According to another wire guide member of the present invention, at least the contact portion with the wire is made of 60 to 99% by weight of Al ₂ O ₃ ,
The i in terms of TiO ₂ 0.2 to 5 wt%, the Mg Mg
It is composed of an alumina-based sintered body containing 0.1 to 3% by weight in terms of O, and oxide particles containing Mg are dispersed in the grains of the alumina crystal phase and in the grain boundaries.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described with reference to FIG. FIG. 1 is a schematic view of a wire electric discharge machine, FIG. 2 is a sectional view of a guide roller, and FIG.

In the wire electric discharge machine A shown in FIG.
Is a metal wire, 2 is a guide roller serving as a guide member for the wire 1, 3 is a nozzle, 4 is an energizing terminal, 5 is a workpiece,
Reference numeral 6 denotes a roller on which the wire 1 has already been wound, and reference numeral 7 denotes a roller on which the wire 1 is wound.

The wire 1 is guided by the guide roller 2 in the direction of the arrow in the figure. The wire 1 contacts the workpiece 5 via the nozzle 3 and the energizing terminal 4 and is guided by the guide roller 2 below. It is wound up.

Then, the wire 1 is used as one electrode,
A voltage is applied to the workpiece 5 to cause a discharge phenomenon, thereby causing the workpiece 5 to be electrically corroded to perform cutting and shape processing.

Further, a guide roller 2 as a wire guide member, a nozzle 3, an energizing terminal 4, a workpiece 5, a roller 6,
In 7, the contact portion with the wire 1 is made of the alumina sintered body having the above-described configuration.

For example, a guide roller 2 shown in FIG.
According to the method, the adhesive 2 made of an epoxy-based adhesive, an acrylic-based adhesive, or an inorganic adhesive is provided around the cylindrical mounting bracket 22.
In this configuration, the ceramic body 21 of the alumina-based sintered body serving as the contact portion is joined through a knurl 3, and the outer periphery of the mounting bracket 22 is subjected to knurling to increase the joining strength with the adhesive 23. I have. The mounting bracket 22 has a through hole 22a having a key groove, and is attached to the through hole 22a through a shaft.

In the current-carrying terminal 4 shown in FIG.
And is formed of an alumina sintered body having a low specific resistance by containing a large amount of TiO ₂ . By applying a voltage to the energizing terminal 4 and guiding the wire 1 by inserting the wire 1 through the through hole 4a,
A voltage is applied to the wire 1.

The contact portions of the ceramic body 21 and the cylindrical body of the current-carrying terminals 4 are made of an alumina-based sintered body, and oxide particles containing Ti are precipitated on the surface of alumina crystal grains and over grain boundaries. By dispersing, residual stress is formed at the quasi-grain boundary and the minute region, the hardness is remarkably improved, and the wear due to the shedding can be effectively suppressed, and as a result, the wear resistance and chipping resistance are greatly improved. And a longer life is achieved.

In order to prepare an alumina-based sintered body in which oxide particles containing Ti are dispersed as described above, a compound containing Ti and other additives are added to alumina powder, and a molded body of such a mixture is formed. Heating in a reducing atmosphere, thereby forming a solid solution of Ti in Al ₂ O ₃ , and then heating in an oxidizing atmosphere to form Ti into an oxide, thereby forming Ti in an alumina crystal phase and at grain boundaries. It is characterized in that oxide particles containing Ti are precipitated and dispersed.

In place of such a production, a molded body made of a mixture containing a compound containing Ti and Mg or other additives is heated in an oxidizing atmosphere to obtain Ti and Mg.
Is dissolved in Al ₂ O ₃ , and then heat-treated in a reducing atmosphere to dissolve Ti in Al ₂ O ₃ and to use Mg as an oxide in the crystal grains and in the grains of Al ₂ O _3. It may be precipitated and dispersed in the field.

The oxide phase containing Ti and Mg is, for example, TiO ₂ , Al ₂ TiO ₅ , RE ₂ Ti ₂ O
₇ (RE is a rare earth element), MgO, MgAl ₂ O _4, etc., all of which have excellent chemical and thermal stability, do not impair the oxidation resistance of the guide member for wire electric discharge machining, The hardness is greatly improved, resulting in a wire guide member with excellent wear resistance and long life.

If the Ti content of the alumina-based sintered body is small, the volume fraction of the dispersed particles is small, and the effect of improving the wear resistance is small. A coarse Al ₂ TiO ₅ phase is formed, and minute cracks are generated due to a difference in thermal constant from the parent, which reduces the fracture resistance of the guide member for a wire electric discharge machine.

[0021] Thus, according to the present invention, the Ti content in the sintered body in terms of TiO ₂ 0.2 to 5% by weight, preferably to 0.5 to 3% by weight.

With respect to the Mg content, if the Mg content is small, the volume fraction of the dispersed particles is small, and the effect of improving the wear resistance is reduced. If the Mg content is large, sintering is hindered, and a dense sintered body is formed. It is difficult to obtain. Therefore, in the present invention,
The Mg content is 0.1 to 3% by weight, preferably 0.1 to 2% by weight in terms of MgO.

With respect to the crystal grain size of the Al ₂ O ₃ mother phase, if the average grain size is 10 μm or less, preferably 5 μm or less,
This is good in that the strength is increased to improve the fracture resistance.

When the size of the oxide particles containing Ti or Mg dispersed in the crystal phase grains of Al ₂ O ₃ and in the grain boundaries is small, the distance between the dispersed particles is small and the gap between the dispersed phase and the parent phase is small. By maintaining the crystal consistency, the strain at the interface is large, and a large hardening effect is brought about. In order to sufficiently exhibit the effect of improving the abrasion resistance, the average particle diameter of the oxide particles containing Ti or Mg is preferably 0.2 μm or less.

In the highly wear-resistant alumina sintered body of the present invention, the oxide particles containing Ti or Mg may be uniformly dispersed from the surface to the inside, but at least 0.01 mm or more from the surface of the ceramic. It is preferable to form a wear-resistant layer in which the oxide particles containing Ti or Mg are dispersed in a region up to the depth of. From the viewpoint of improving the service life of the guide member, the thickness of the wear-resistant layer is preferably 0.02 μm or more.

Further, rare earth elements, Zr, Hf, Mo, W
Is excellent in chemical stability, has a great effect of suppressing the growth of alumina crystal grains, and improving the strength of the guide member.
Also, the presence of Si oxides can significantly improve the toughness of the material by promoting anisotropic growth of alumina crystals. In the highly wear-resistant alumina-based sintered body of the present invention, it is important to add the above oxide.
The addition amount is preferably 0.3 to 35% by weight.

In order to produce the highly wear-resistant alumina-based sintered body of the present invention, first, a predetermined amount of a Ti-containing compound and a Mg-containing compound are added to alumina powder having an average particle size of 0.1 to 1 μm and mixed. I do. The compound may be any of oxide powder, metal powder, organic salts, inorganic salts and a solution thereof. The above mixture is formed into an arbitrary shape by a desired forming means, for example, a die press, a cold isostatic press, a casting, an injection molding, an extrusion molding, or the like. Next, the formed body is subjected to a known sintering method, for example, a hot press method, a normal pressure sintering method, a gas pressure sintering method, a microwave heating sintering method, and a hot isostatic pressure (HIP) treatment after sintering. Sintering is performed by various sintering techniques, such as after glass sealing (HIP).

According to the present invention, in the calcination, heat treatment is performed in a reducing atmosphere in which Ti can be dissolved in the alumina crystal, and then heat treatment is performed in an oxidizing atmosphere in which Ti can be precipitated as oxide from the solid solution. Alternatively, heat treatment is performed in an oxidizing atmosphere in which Ti and Mg can form a solid solution in alumina crystals, and then heat treatment is performed in a reducing atmosphere in which Mg can be deposited as an oxide from the solid solution. The compact is fired densely by using any of the heat treatment steps described above. However, heat treatment is performed after such dense firing, or HIP is performed after solid solution and precipitation to densify. Good.

By adding a Ti compound to alumina,
When Ti is heat-treated in a reducing atmosphere, the ionic valence of Ti becomes 3+, the solubility in alumina crystals increases, and a solid solution is formed. Then, by treating this solid solution in an oxidizing atmosphere, the ionic valence of Ti becomes 4+, and the solubility in the alumina crystal is reduced.
i is mainly deposited as TiO ₂ and Al ₂ TiO ₅ .

When a compound containing Ti and Mg is simultaneously added to alumina, if the compound is treated in an oxidizing atmosphere, T
i and Mg can be simultaneously dissolved in alumina crystals at the same molar ratio. Then, by treating this solid solution in a reducing atmosphere, the ionic valence of Ti becomes 3+, and the Ti alone is preferentially dissolved in alumina. Since Mg alone cannot be dissolved in alumina, it is mainly deposited in the form of MgAl ₂ O ₄ . Examples of such a reducing atmosphere include a hydrogen-containing atmosphere, an inert gas atmosphere, and a high vacuum atmosphere having an oxygen partial pressure of 10 ⁻⁶ atm or less. The treatment in the oxidizing atmosphere is performed in the air.

Further, when the temperature at the time of such solid solution or precipitation treatment is low, the required structure is not formed, and alumina crystal grains and precipitated particles are coarsened. Therefore, regarding the temperature at the time of solid solution or precipitation,
It is good to make it in the range of 0 to 1600 ° C.

Thus, according to the wire guide member of the present invention, the contact portions such as the ceramic body 21 and the cylindrical body of the current-carrying terminals 4 are made of the above-mentioned alumina sintered body, thereby providing excellent wear resistance. (Vickers hardness: 1600 kg /
mm or more) and high toughness (fracture toughness value (K1C): 4M)
Pa√m or more), whereby the composition could be used for a long period of time.

Further, according to the present invention, the conductivity can be increased because the electric resistance is sharply reduced in firing in a hydrogen atmosphere when 2% by weight of TiO ₂ is added. Therefore, by utilizing this characteristic, the current-carrying terminal 4 shown in FIG.
A cylindrical body having a through hole as shown in FIG.

[0034]

Next, an embodiment of the present invention will be described in detail with a guide roller 2 shown in FIG. (Example 1) A ceramic body 21 (outer diameter: 57 mm) of the guide roller 2 was made of various ceramic materials.

Alumina (Al ₂ O ₃ ) powder and titanium oxide (TiO ₂ ) powder were prepared as raw material powders at the composition ratios shown in Table 1, press-molded at a pressure of 1 ton / cm ² , and then 3 ton / cm ² Cold isostatic pressing (CIP) at a pressure of cm ²
To obtain a molded body. This compact was fired for 2 hours under the firing conditions shown in Table 1 and then heat-treated for 2 hours under the heat treatment conditions shown in Table 1.

[0036]

[Table 1]

These sintered bodies (ceramic bodies 21) were processed into mirror surfaces, and precipitated particles in alumina crystal particles were confirmed on a scanning electron micrograph, and α-Al in the sintered bodies was determined by X-ray diffraction measurement. Crystals other than ₂ O ₃ were identified.

Further, the flexural strength is determined by JIS-R1601, and the fracture toughness (KIC) is determined by Vickers indentation method.
According to JIS-Z2244, Vickers hardness (load 1)
kg) was measured for the wear rate by the pin-on-disk method (load 1 kg, speed 5 m / sec, 5 minutes).

In addition, conventional zirconia (as a main component, Z
rO, slightly containing Al ₂ O ₃ and Y ₂ O ₃ ), silicon nitride (Si ₃ N ₄ as a main component, slightly Al ₂ O ₃ and Y ₂ O)
₃ ), and the same measurement was performed for alumina. The results shown in Table 1 were obtained.

As is clear from Table 1, the sample N of the present invention
o. As for Nos. 3 to 5, it can be seen that the abrasion speed is significantly reduced.

Example 2 In this example, as shown in Table 2, magnesium oxide (MgO) was further added, and various samples were similarly prepared. You can see that.

[0042]

[Table 2]

(Example 3) As a material of the ceramic body 21, a sample No. shown in Table 1 was used. Using 3 to 8 and conventional zirconia, silicon nitride, and alumina, each was equipped with the wire electric discharge machine shown in FIG. 1 and an actual machine test was performed.

In this test, using a wire having a wire diameter of 0.1 mm under normal processing conditions, the time required for the wear amount of the ceramic body 21 to reach 30 μm was examined. is there. The mark “○” indicates that the time was about 500 hours or more and the abrasion resistance was excellent, and the device could be used for a long period of time. The mark “X” indicates that the abrasion resistance was poor.

[0045]

[Table 3]

As is clear from the results shown in Table 3, when the ceramic body 21 made of the alumina-based sintered body of the present invention is used, extremely good abrasion resistance is obtained, and the life is about three times that of the comparative example. It can be extended and its replacement frequency has been reduced.

[0047]

As described above, according to the wire guide member of the present invention, the contact portion with the wire is made of a wear-resistant alumina sintered body having a specified composition, so that the diameter is several tens μm.
Even if a wire having an extremely small diameter is used, the abrasion is reduced, and as a result, a wire guide member having a long life and reduced production cost can be provided with less frequent replacement.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a wire electric discharge machine according to the present invention.

FIG. 2 is a sectional view of a guide roller.

FIG. 3 is a sectional view of an energizing terminal.

[Explanation of symbols]

 A wire electric discharge machine 1 wire 2 guide roller 3 nozzle 4 energizing terminal 5 workpiece 6 roller 7 roller 21 ceramic body

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuo Mukai 1-1, Yamashita-cho, Kokubu-shi, Kagoshima Kyocera Corporation Kokubu Plant (72) Inventor Hirofumi Igarashi 1-1, Yamashita-cho, Kokubu-shi, Kagoshima Kyocera Corporation F-term (reference) in Kokubu Plant of Shikisha 3C059 AA01 AB05 FB04

Claims (2)

[Claims] At least a contact portion with a wire is made of Al ₂ O ₃
60-99 wt%, 0.2 in terms of Ti to TiO ₂
A wire guide member comprising an alumina-based sintered body containing 5% by weight, wherein oxide particles containing Ti are dispersed in grains of an alumina crystal phase and in grain boundaries. 2. The method according to claim 1, wherein at least the contact portion with the wire is made of Al ₂ O ₃
60-99 wt%, 0.2 in terms of Ti to TiO ₂
An alumina sintered body containing 5% by weight and 0.1 to 3% by weight of Mg in terms of MgO, and oxide particles containing Mg dispersed in the grains of the alumina crystal phase and in the grain boundaries. A wire guide member characterized by the above-mentioned.