JPS62244107A - Precision casting yoke - Google Patents

Abstract

PURPOSE:To inhibit enlargement more than required in a crystal grain, and to increase resistance while facilitating a manufacturing process after casting by adding fixed quantities of Ti, Zr, Nb and Al to an Si-Fe group alloy singly or compositely. CONSTITUTION:An alloy in which 2-4.5 wt.% Si, at least one kind or two kinds or more of Ti, Zr and Nb at 0.01-1 wt. % and 0.01-0.5 wt. % Al at a weight percentage are added singly or compositely while C is brought to 0.010 % or less and 0 to 0.03% or less is used in an Fe-Si group alloy as a casting for a precision casting yoke l. Accordingly, straightening important for the precision casting yoke with miniaturization and the enhancement of accuracy, mandays in a machining process and yield can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a precision cast yoke that constitutes a magnetic path of a dot printer print head.

[Conventional technology]

The yoke material used as a component of the print head of dot type printers is one of the peripheral devices associated with computers, which have become rapidly popular in recent years.
Silicon steel is widely used. Among these, yokes with a large number of pins, such as 18 or 24 pins for kanji or graph ink, have complex shapes and require high precision, so they are generally made of 1 to 3 wt% St steel. The material used is precision casting with some machining applied.

FIG. 1 shows a principle diagram of a dot printer print head including a yoke. By passing a pulse current through coil 2,
The action and reaction of the magnetic force excited in the yoke 1 and the spring force or the magnetic force of a permanent magnet causes the movable piece (armature) 3 to be attracted to or detached from the yoke 1, and the dot printing wire 5 fixed to the movable piece is A desired dot is printed by striking the printing paper 8 inserted into the surface of the platen 7 through the ink ribbon 9 at the tip.

Generally, precision cast yokes used as yoke materials are required to have the following characteristics.

(1) Good magnetic properties.

Since excitation is repeated at high speed, the maximum magnetic permeability μmax is large, and the coercive force Hc is small, resulting in excellent soft magnetism, and the magnetic flux density B is large to ensure printing pressure.

(2) The specific resistance value is large.

High resistivity and low eddy current loss to prevent variations in printing pressure due to heat generated during long-term use.

(3) Good castability and few casting defects.

Micro-cavities and inclusions reduce the magnetic properties of the yoke, and also cause cracks and chips in machining processes such as strain relief and cutting after casting, reducing yields. is good.

(4) Must have toughness.

After precision casting, yokes are often subjected to strain relief work to correct the alignment and pitch between the columns, and the end faces of the column heads are cut and polished, so the yokes must have the toughness to withstand the strain relief and machining required. thing.

(Problem to be solved by the invention) However, the stm of 1%, 2.5%, 3%, etc. that have been conventionally used as precision casting yoke materials all have advantages and disadvantages, and some of the required properties may be sacrificed. They were used differently depending on the purpose.

In recent years, as printers have become smaller and faster, 3% S1 steel, which has excellent soft magnetism, high magnetic flux density, and high specific resistance, has come to be used more often, but as the amount of Si content increases, the toughness decreases. As a result, the post-casting process becomes complicated, and a decrease in yield cannot be avoided. In order to pursue even smaller size and higher performance, the dimensional accuracy required for precision cast yokes cannot be satisfied with normal as-cast tolerances, and more and more parts are being subjected to distortion correction or machining. Damage, etc. is a factor that causes a decrease in yield.

In view of these points, the present invention provides a novel precision casting yoke that maintains or improves electrical and magnetic properties without adversely affecting castability, and also facilitates the manufacturing process after casting.

[Means for solving problems]

The present invention uses 5i containing 2.0 to 4.5% by weight of Si.
- In a precision cast yoke for dot printers made of Fe-based alloy, Ti, Zr, and Nb are used alone or in combination in a total amount of 0.01 to 1.0% by weight and Al in a total amount of 0.010 to 0.5% by weight. and contains 0.0 C.
10% by weight or less and O 0.030% by weight or less, balance F
This is a precision cast yoke characterized by being made of e and unavoidable impurities.

The present invention improves the above-mentioned drawbacks of cast yokes. That is, Ti is added to the 5i-Fe alloy.

By adding Zr, l'Jb, and A1 in predetermined amounts alone or in combination, it is possible to suppress unnecessarily coarsening of crystal grains and increase resistance. It has been confirmed through experiments that by reducing the amount of O in the molten metal through auxiliary deoxidation, the number of oxide inclusions that can become a starting point for breakage can be reduced, and that both of these effects can make handling after casting easier. It is based on

In addition, for the magnetic properties that tend to deteriorate with the addition of these alloying elements, by suppressing C to 0.010% by weight or less, it is possible to suppress the crystal grains from becoming finer to a level that would adversely affect soft magnetism. At the same time, by preventing the generation of minute pearlite that can precipitate at grain boundaries and become a reverse magnetic field, and by regulating 0 to 0.03% by weight or less, the proportion of minute deoxidation products that exist in the molten metal is significantly reduced. The inventors have discovered that it is possible to recover the magnetic properties by reducing the amount of carbon, leading to the present invention.

Next, the reasons for limiting the alloy components in the present invention and their effects will be specifically explained. First, Si is 2 to 4.5
The reason why it is limited to % by weight is that the properties of specific resistance, saturation magnetic flux density, coercive force, and maximum magnetic permeability have a suitable balance as a yoke material, and if it is less than 2% by weight, the maximum permeability is too low. Moreover, since it already has relatively toughness, it deviates from the objective of the present invention, and the St content is 4.5% by weight.
If it exceeds the above, the saturation magnetic flux density will decrease, and the toughness will be extremely reduced, making it difficult to make a cast product, and thus having little practical use. Ti, Zr, and Nb form fine carbonitrides, so they refine crystal grains, improve toughness, and
Increases resistivity.

However, if the amount of one or more types added is less than 0.01% by weight, this effect is hardly seen, and if it exceeds 0.5%, the particle refining effect disappears, and conversely, the deoxidized product is not floated and separated. It solidifies and remains in the cast product, increasing the rate of cleanliness deterioration and inhibiting the vortex flow necessary for casting precision cast yokes with complex shapes. In addition, these Ti
, Zr, Nb.

By adding a specified amount of A4 to the molten metal that has been sufficiently deoxidized in advance, in addition to the above grain size adjustment effect, the O in the steel is further reduced due to the deoxidation reaction of a part of the added alloy, and the O content in the steel is reduced during the cooling process after casting. It has the secondary effect of reducing secondary deoxidation products.

The reason why C is limited to 0.010% by weight or less is that if it exceeds 0.010% by weight, the proportion of fine pearlite that tends to precipitate at grain boundaries increases, and this acts as a reverse magnetic field, and the above-mentioned This is because the crystal grains become finer and the soft magnetism deteriorates.

The reason why 0 is set to 0.03% by weight or less is because if it exceeds 0.03% by weight, Ti and Zr will be removed in normal melting operations.

This is because a large proportion of Nb and Al are consumed as deoxidizers, which loses their original meaning as additive alloys and deteriorates the cleanliness of the cast product.

Note that Mn may not be added, but if it is added for the purpose of enhancing the deoxidizing effect and stabilizing the yield of Si as an additive alloy, it should be added within a range of 0.5% by weight or less so that the maximum magnetic permeability does not decrease excessively. It is better to

〔Example〕

The present invention will be explained below with reference to Examples.

The alloys with the components shown in Table 1 were heated in a high frequency induction melting furnace to
0 kg each was melted and cast into a mold manufactured by the lost wax precision casting method. The comparative material contains Ti, Zr, Nb, and Al, each singly or in combination, within the scope of the present invention, but contains either or both of C and 0 beyond the limits of the present invention.

The mold is φ33×φ45×5 with my magnetism measurement ring,
The test piece for the cutting test shown in Fig. 2 and the φ5 x 1007 specimen used for the bending test, specific resistance measurement, and cleanliness test! It is possible to collect the required number of m+m rod-shaped test pieces. After casting, the mold material was removed, and the sprue of each specimen was cut and polished, and the specimens were tested. Regarding magnetic properties and resistivity, 1050'cX
After holding for 3 hours and cooling to room temperature at 180° C./hour, the sample was subjected to a test.

A DC magnetization characteristic test was conducted using a magnetic measurement ring, and the coercive force Hc and maximum magnetic permeability μmax % were determined from the hysteresis curve.
The magnetic flux density B was read. The specific resistance value is φ5×100j after the heat treatment! Parallel polishing of a rod-shaped specimen of m■
Measurements were made using a test piece finished at 4.6w.

Cleanliness was determined by cutting and polishing a φ5fi rod-shaped specimen in the axial direction.
Tested according to JISGO55.

For the bending test, the 10W width of the end of the rod-shaped test piece was fixed in a vise, and the occurrence of cracks was examined when one end was bent at 15 degrees with respect to the vise fixed part. Ten pieces of each composition were tested, and the occurrence of cracks was determined. The number of tested specimens was counted.

For the cutting test, one part of the test piece shown in Fig. 2 with a diameter of 1 mm was fixed in a vise, and the end of the column was cut with a diameter of 20 m1 + high-speed steel end mill to a depth of 2 cranes, a rotation speed of 600 rpm, and a feed of 0.02 dragon/rev. Total of 5 at JlJj
0 columns were processed, and the number of columns with missing or cracked column roots was counted.

The results of these tests and measurements are shown in Tables 2 and 3. In these tables, the sample size corresponds to that in Table 1.

Table 2 shows that the material of the present invention is superior to the conventional material as a soft magnetic material, with coercive force, maximum i3 magnetic flux density, and magnetic flux density being small, large, and large, respectively, and the specific resistance is approximately the same. It turns out that. It can be seen that the comparative material is inferior to the conventional material in terms of coercive force, maximum permeability, and magnetic flux density.

Table 3 Next, from Table 3, the material of the present invention has a slightly finer grain size and a slightly lower cleanliness than conventional materials, and the number of defects in the cutting test and the number of cracks in the bending test are extremely high. low,
Therefore, it can be seen that damage caused by machining and distortion correction can be significantly reduced.

The comparison material has inferior properties as a soft magnetic material compared to the conventional material as shown in Table 2, but the number of defects and cracks in Table 3 are significantly lower, so we place special emphasis on high speed, miniaturization, etc. It may be possible to use it as a yoke material for dot printers that do not require printing.

C. Effects of the invention] As explained above, the high-performance precision casting yoke of the present invention has the following effects:
Si in weight% in Fe-5i alloy as casting material
:2 to 4.5% by weight, Ti, Zr.

0.01 to 1% by weight of any one or two or more types of Nb and 0.01 to 0.5% by weight of All are added singly or in combination, and C is added to o, oto% or less, and O is added to 0.
．． 0.03% or less.

In addition, it is possible to significantly improve the number of man-hours and yield in post-casting distortion correction and machining processes, which are becoming inevitable for precision casting yokes as miniaturization and higher precision are achieved. This enables mass production of yokes. In addition, since the magnetic flux density among magnetic properties has been particularly improved, it is possible to make the yoke smaller or increase the number of simultaneous prints by increasing the printing pressure, which is an industrially significant effect in mass producing high-performance compact yokes. It has the following.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a cutting test piece using an example of the present invention;
FIG. 2 is a principle diagram of a dot printer print head including a yoke.

Claims (1)

[Claims] In a precision cast yoke for a dot printer made of a Si-Fe alloy containing 2.0 to 4.5% by weight of Si, a total of 0.01 to 1.0% by weight of Ti, Zr, alone or in combination.
and Nb and 0.010 to 0.50% by weight of Al, singly or in combination, with C of 0.010% by weight or less, O of 0.030% by weight or less, and the remainder consisting of Fe and unavoidable impurities. A precision cast yoke featuring: