JP3061849B2 - Sintered Fe-Co-V alloy and method for producing the same - Google Patents

Description

The present invention relates to a sintered Fe—Co—V alloy suitable as a material for forming a magnetic circuit component and a method for producing the same.

(Prior art) Fe-Co alloy containing about 50% by weight of Co has a high saturation magnetic flux density and a high magnetic permeability, and a low coercive force.
It is used as a material for forming various magnetic circuit components, and is used, for example, in the yoke and armature of a print head mounted on a dot matrix printer.

This type of print head performs printing by selectively releasing many armatures from the magnetic force of permanent magnets by forming a magnetic circuit of the electromagnets from yoke to armature when the electromagnet is driven. It is. In such a print head, in order to improve the responsiveness of the armature and improve the high-speed printing performance, a material having a high saturation magnetic flux density and a high magnetic permeability as a material for forming the yoke and the armature, that is, It is desired to have a small volume that can sufficiently transmit magnetic flux. In general, Fe-Co alloys are often used to satisfy such conditions.

As a general method for producing the above-mentioned Fe-Co alloy, a casting method can be used as in the case of a normal alloy. However, an Fe-Co alloy obtained by the casting method has a drawback that cold workability is poor. For example, the yoke in the above-described print head has a very complicated shape for driving a large number of armatures, and is formed by cold working from an ingot obtained by a casting method. It is difficult to produce a magnetic circuit component having a complicated shape, and it is very uneconomical in terms of manufacturing cost.

On the other hand, as a further improvement of the workability and AC magnetic properties of Fe-Co alloy, Fe-Co alloy containing about 2% by weight of V
Although -V alloys are known, they do not have workability enough to efficiently form a complex-shaped product as described above.

Therefore, the use of powder metallurgy has been studied.
For example, Japanese Patent Application Laid-Open No. 54-75410 discloses that 35-45 wt% V-Co
By using a mixed powder of alloy powder and Fe powder, sintered Fe-
It is described to produce a Co-V alloy.

(Problems to be Solved by the Invention) However, in the above-described method for producing a sintered Fe-Co-V alloy, a V-Co alloy powder containing V in a large amount of 35 to 45% by weight as a starting material of the V component. When a sintered Fe-Co-V alloy having a low V content of about 2% is used, the distribution of V in the alloy structure tends to be non-uniform, and uniform magnetic properties can be obtained. There was a problem that it was difficult. This also had the disadvantage that V-Co alloy powder was relatively expensive.

Also, sintered Fe-Co-V alloys by powder metallurgy have a lower density than those by casting, and have the disadvantage that magnetic properties, such as magnetic flux density and magnetic permeability, are reduced, When V is added, the decrease in the magnetic flux density and the like is particularly increased. This is because, in the conventional powder metallurgy method, sufficient strength cannot be obtained unless sintering is performed at a high temperature near the melting point, so that grain growth easily occurs in a sintered body obtained by this high-temperature sintering, It is thought to be due to the characteristics of V itself.

Thus, sintered Fe-Co-V by the conventional powder metallurgy method
At present, magnetic properties comparable to those of Fe-Co-V alloys obtained by casting methods have not been obtained.

The present invention has been made in order to address such a problem, and has the same magnetic properties as an Fe-Co-V alloy by a casting method, and can be manufactured at low cost by using sintered Fe-Co-. An object of the present invention is to provide a sintered Fe-Co-V alloy suitable for a magnetic circuit component having a complicated shape such as a yoke for a dot matrix type print head, and a method for producing the same. .

[Structure of the Invention] (Means for Solving the Problems) That is, the present invention solves the above problem by using Co40 to 60 wt%
Fe-V alloy powder containing about 5 to 5% by weight, the balance being Fe and inevitable impurities, the Fe-V alloy powder containing 30 to 70% by weight of V having a particle diameter of 325 mesh or less. And Fe-based powder, and a sintered Fe-Co obtained by sintering a mixed powder of Co powder having a particle diameter of 325 mesh or less.
The problem was solved by providing a -V alloy.

The sintered Fe-Co-V alloy of the present invention has a size of 325 mesh or less.
Fe-V alloy powder and Fe-based powder containing 0 to 70% by weight of V;
It is obtained by powder metallurgy using a mixed powder with Co powder of 25 mesh or less, and contains Co in a range of 40 to 60% by weight and V in a range of 1 to 5% by weight. . this
When Co is less than 40% by weight, the magnetic flux density and magnetic permeability are low.
If it exceeds 10% by weight, the magnetic flux density and the magnetic permeability decrease again. On the other hand, if V is less than 1% by weight, the effect of improving AC magnetic characteristics and the effect of improving workability due to an increase in electric resistance cannot be sufficiently obtained, and if it exceeds 5% by weight, the decrease in magnetic flux density increases.

The Co component is constituted by Co powder having a mesh size of 325 mesh or less. Various types of Co powder, such as reduced Co powder and electrolytic Co powder, can be used as the Co powder, and the use of the Co powder improves the moldability of the compact, particularly the strength of the compact. It is also preferable to use Co powder from the viewpoint of combination with Fe-based powder containing V.

Fe component and V in the sintered Fe-Co-V alloy of the present invention
The component is composed of Fe-V powder containing V of 325 mesh or less. As the Fe-V-based powder containing V, it is particularly preferable to use Fe-V alloy powder alone. the above
When using the Fe-V alloy powder alone, the composition ratio of V in the alloy powder, after taking into account the V content of the target Fe-Co-V alloy and the type of Co powder to be used, For example, it is preferably about 30 to 70% by weight. Thereby, the uniformity of V in the mixing stage of the raw material powder is secured, and even if the amount of movement of V at the time of alloying is small, the Fe-Co
A -V alloy is obtained.

From these points, particularly preferred raw material compositions in the present invention include Fe-V alloy powder containing 30 to 70% by weight of V.
Combination with Co powder.

In the present invention, the Fe-based powder containing V and Co
Both powders are characterized by using those having a mesh size of 325 mesh or less, thereby improving both the formability and the sinterability, the sintered body density is high, and the sintered Fe-
It becomes a Co-V alloy. A more preferable particle size for these raw material powders is an average particle size of 30 μm or less.

The sintered Fe-Co-V alloy of the present invention is manufactured by, for example, the following method.

First, Fe containing 325 mesh or less and containing 30 to 70% by weight of V
-V alloy powder, Fe-based powder and Co powder are mixed so as to have a desired composition, and this mixed powder is formed into a desired shape by a pressure molding method or the like to obtain a green compact. Next, the green compact is fired and sintered to obtain a sintered Fe—Co—V alloy having a desired shape. In this sintering, sintering can be performed at a relatively low temperature because the surface energy is high because powder having a fine particle diameter is used.

By sintering the fine powder at a relatively low temperature, a sintered Fe—Co—V alloy having an average crystal grain size controlled to 30 μm or less is obtained, and the relative sintering density is 95%. The above is excellent. By minimizing the average crystal grain size of the sintered Fe-Co-V alloy to 30 μm or less, the electrical resistance is increased, so that the iron loss is reduced and heat generation can be suppressed as much as possible when used in a high frequency range. It becomes possible. Therefore, it is suitable for magnetic circuit components used in an alternating magnetic field, for example, the yoke of a dot matrix type print head.

(Operation) The sintered Fe—Co—V alloy of the present invention has a fine particle diameter of 325 mesh or less, and contains 30 to 70% by weight of V
Since V alloy powder and Co powder are used, the density of the sintered body is improved. Therefore, it is possible to improve the workability and the AC magnetic characteristics by adding V, and to suppress the decrease in the magnetic characteristics such as the magnetic flux density as much as possible. Further, by using Fe-V alloy powder having a fine particle diameter and containing 30 to 70% by weight of V, Fe-based powder and Co powder, energy required for sintering can be reduced. Sintering at a very low temperature becomes possible. Therefore, it is possible to suppress the growth of the crystal grain size from these facts. Further, since a V-containing Fe-V-based powder is used as a starting material for V,
It also contributes to a reduction in manufacturing costs.

(Example) Next, an example of the present invention is described.

Example 1 First, Fe-containing 50% by weight of V of 325 mesh or less was used.
V alloy powder and Fe powder, and reduced Co powder of 325 mesh or less (average particle diameter 20 μm) were prepared.
e: Co: V = 49: 49: 2, weighed and 1% by weight
Was added and mixed.

Then, 32 mm × 24 the mixed powder at a molding pressure of 6 ton / cm ²
It was compacted into a shape of mm × 5 mm.

Next, after degreased at 400 ° C., the formed body was fired and sintered in a hydrogen atmosphere at 950 ° C. for 3 hours.
The desired sintered Fe-Co-V alloy was obtained.

When the average crystal grain size at an arbitrary position of the sintered Fe—Co—V alloy thus obtained was measured by SEM microscopic observation, a fine value of 20 μm was obtained. Also this sinter
Using a Fe-Co-V alloy, the relative sintered body density and the magnetic flux density B50 in a magnetic field of ₅₀ Oe were measured. Table 1 shows the results.

Comparative Example 1 Carbonyl Fe powder of 325 mesh or less (average particle diameter 30 μm)
m) and reduced Co powder of 325 mesh or less (average particle diameter 20μ)
m) and Co- containing 50% by weight of V of 325 mesh or less.
A sintered Fe-Co-V alloy was produced under the same conditions as in Example 1 except that V alloy powder (average particle diameter 30 μm) was used,
Each characteristic was measured in the same manner as in Example 1.

As is clear from the results in Table 1, the sintered Fe—Co—V alloy according to Example 1 has a higher sintered body density and a smaller crystal grain size than those of Comparative Example 1, As a result, each magnetic property also shows an excellent value. In particular, Comparative Example 1 was inferior in magnetic properties to the sintered Fe-Co-V alloy of Example 1 despite using fine powder as the raw material powder. This is considered to be due to the use of V-Co alloy powder as a starting material for V. Further, the sintered Fe-Co-V alloy of Example 1 was made of Fe-Co-V
It had almost the same magnetic properties as the alloy.

Next, by using the same raw material powder and the same process as in Example 1, the yoke 1 of the dot matrix printer head shown in FIG. An inner yoke 3 having a large number of upright portions 3a was prepared. As a result, even with such a complicated shape, the reproducibility of the shape was excellent, and the magnetic characteristics were also excellent as in the first embodiment.

Using the yoke 1, an auxiliary yoke 5 is installed on the upper side of the outer yoke 2 via a permanent magnet 4 as shown in FIG. An armature 7 provided with a printing wire 6 is supported so as to be positioned above the inner yoke 3, and a coil 8 is installed on each of the upright portions 3 a of the inner yoke 3 to form a dot matrix type print head. Was configured.

When the print head having the above configuration was assembled in an actual machine and a printing test was performed, good high-speed printing could be continuously performed.

[Effects of the Invention] As described above, according to the present invention, the sintered body has a high sintered body density and a fine crystal grain size even for a complicated shaped body.
The present invention can provide an Fe-Co-V alloy, and is therefore suitable for various magnetic circuit components and the like having a complicated shape and requiring excellent magnetic properties.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a dot matrix type print head using a sintered Fe-Co-V alloy according to one embodiment of the present invention. 1 ... Yoke made of sintered Fe-Co-V alloy, 2 ... Outer yoke, 3 ... Inner yoke, 4 ... Permanent magnet, 5 ... Auxiliary yoke, 6 ... Print wire, 7 ... Armature, 8
……coil.

Claims (4)

(57) [Claims] 1. A sintered Fe--Co alloy containing 40 to 60% by weight of Co and 1 to 5% by weight of V, with the balance being Fe and unavoidable impurities.
-V alloy having a particle size of 325 mesh or less3
Fe-V alloy powder and Fe-based powder containing 0 to 70% by weight of V;
A sintered Fe-Co-V alloy obtained by sintering a mixed powder with a Co powder having a particle diameter of 25 mesh or less. 2. The sintered Fe—Co—V alloy according to claim 1, wherein said sintered Fe—Co—V alloy is a yoke member for a dot matrix type print head.
Co-V alloy. 3. A particle having a particle diameter of not more than 325 mesh and having a particle diameter of 30 to 70.
Mixing Fe-V alloy powder and Fe-based powder containing V by weight% and Co powder having a particle diameter of 325 mesh or less,
A sintered Fe-Co-V containing 60% by weight and 1 to 5% by weight of V, the remainder being a mixed powder comprising Fe and unavoidable impurities, which is subjected to pressure molding, followed by degreasing and sintering. Alloy manufacturing method. 4. The method for producing a sintered Fe-Co-V alloy according to claim 3, wherein a lubricant is added when the Fe-V alloy powder, Fe-based powder and Co powder are mixed. For producing a sintered Fe-Co-V alloy.