JPH09327744A - Sizing method of metal stock body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform high precision sizing by pressurizing at a specified pressure after the metal stock body is heated to a specified temp. or more so as to reduce variance in dimensions of metal stock body and improve yield. SOLUTION: Sizing is performed so that the metal stock body, after putting in an introducing part of a pestle die heated to >=350 deg.C, is pressurized at <=15ton/cm<2> by descending an upper punch 3 and is held for fixed time. After sizing the metal stock body is taken out from die by ascending a lower punch 4. Successively, by cooling, a metal member having a prescribed dimensional precision is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sizing technique for a metal body. More specifically, the present invention relates to a sizing technique for a member used in a driving device such as a motor and requiring high dimensional accuracy.

[0002]

2. Description of the Related Art Conventionally, a metal member has been manufactured by punching a steel plate made of a magnetic material such as Fe--Si alloy or Fe--Ni alloy into a predetermined shape. However, in the punching method, since the thickness of the steel sheet can be punched only up to about 1 mm, there are problems that the shape is limited and waste is generated after punching. Further, since a hard metal material is difficult to punch, the composition region of the material is limited. In the case of Fe-Si alloy, the composition that can be punched is up to about 3 wt% Si content. More Si
If the amount is too high, the hardness becomes high and the toughness becomes weak. Therefore, if the thickness is about 500 μm, punching becomes impossible, and if the thickness is less than that, the steel plate will crack during punching. Therefore, the Fe-6.5 wt% Si alloy, which has been known as a material with high magnetic properties, could not be formed by punching.

In order to obtain a member having high magnetic properties, a method is known in which materials are mixed so as to have a predetermined composition, and then a powder metallurgy method or a casting method is used to obtain a molded body. But,
In such a method, a dimensional change occurs during a manufacturing process such as sintering or melting, so that the product size varies greatly. Therefore, when actually manufacturing a product that requires high dimensional accuracy, it is necessary to select 100% of the products, which reduces the yield. Further, in order to improve the dimensional accuracy, it is necessary to perform cutting after firing. However, although high dimensional accuracy can be achieved by cutting, it is problematic as a practical means because it requires cost and time.

For the Fe member, conventionally, a so-called cold sizing method has been performed in which the plastic deformability of a metal is used to correct the shape by pushing it into a mold having a desired shape at room temperature. This method is effective for metals such as Fe that are highly plastically deformable at room temperature, but in the case of Fe alloy materials to which other elements are added in order to improve magnetic properties, the hardness is high, and Since plastic deformation does not occur in the steel, it has a drawback that it cracks during cold sizing.

Further, Japanese Patent Publication No. 5-35203 discloses F
A method for producing a high-density, high-strength and high-precision spur gear with improved tooth root bending strength by performing precision die forging of an e alloy by warm forging is disclosed. The materials in the composition range described in the publication are not intended to improve the magnetic properties.

[0006]

As described above, according to the conventional method, it is difficult to form a metal material having good magnetic characteristics with high dimensional accuracy because the metal material has high hardness. Therefore, an object of the present invention is to provide a method capable of sizing a metal magnetic material having a good magnetic property in a composition range, particularly an Fe alloy, with high yield, at low cost, and with high dimensional accuracy.

[0007]

This and other objects are attained by the following inventions (1) to (9).

(1) A sizing method for a metal base body, which comprises inserting the metal base body into a mold heated to 350 ° C. or higher.

(2) The sizing method according to (1), characterized in that the metal matrix is fitted into a heated mold and then pressurized at 15 ton / cm ² or less.

(3) The sizing method according to (1) or (2), wherein the metal matrix contains Fe.

(4) The metal matrix is at least Si
3 to 50 wt% is contained, The sizing method as described in (3) characterized by the above-mentioned.

(5) The metal matrix is at least Al
3 to 50 wt% is contained, The sizing method as described in (3) or (4) characterized by the above-mentioned.

(6) The metal matrix is at least Ni.
20 to 80 wt% is contained (3) to
The sizing method according to (5).

(7) The metal matrix is at least Co
Is contained in an amount of 40-60 wt% (3)-
The sizing method according to (6).

(8) The metal matrix is at least Cr
Is contained in an amount of 12 to 25 wt% (3) to
The sizing method according to (7).

(9) The metal matrix contains Cr 12 to 2
The sizing method according to (3), which contains 5 wt% and 4.5 to 20 wt% of Ni.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION By heating a metal above a certain temperature, it becomes possible to plastically deform at a relatively low pressure. The present invention provides a sizing method that can utilize the characteristics to reduce the dimensional variation and improve the yield. Further, the present invention is particularly applicable to materials having good magnetic properties. Hereinafter, the sizing method of the present invention will be described in detail with reference to the drawings.

An example of the hot sizing machine used in the present invention is shown in FIG.

1 is a hot sizing machine used in the present invention. The hot sizing machine 1 is composed of a sizing die (mortar die 2, upper punch 3, lower punch 4) and heating means 5.

The die 2 has a straightening portion 6 for straightening a metal body formed by an arbitrary method to a desired size. It is preferable to make the introduction part 7 large so that the correction part 6 can be inserted even if the shape of the metal matrix sample is slightly varied.
Further, the die 2 is provided with a heating means 5. The die 2 may be heated by an appropriate method such as resistance heating, high frequency induction heating, and condensing heating.

The material of the die 2 may have a hardness higher than that of the metal matrix to be sized, but it is preferable that the die 2 has a high thermal conductivity in order to heat the entire die uniformly and quickly. Specifically, cemented carbide (WC-Co), cermet or the like is used.

When designing the dimensions of the sizing die,
As the temperature is raised, thermal expansion and contraction must be taken into account. If the coefficient of thermal expansion of the metal matrix sample to be sized and the mold are the same, even if the mold expands at a certain temperature, the sample expands similarly and contracts at the same rate during the cooling process. The mold may be designed to the desired size itself. However, if the mold and the sample have different coefficients of thermal expansion, the dimensions must be designed in consideration of this difference.

For example, when the coefficient of thermal expansion of each of the mortar-shaped and metal matrix samples is α ₁ , α ₂ , the die diameter is A (mm), and the sizing temperature is T (° C.), the sample dimensions after cooling are A × T × (α ₂ −α ₁ ) (mm) smaller than the die size.
For this reason, it is necessary to design the mortar die larger than the intended size by the above amount. For this reason, it is preferable to use the die having the same thermal expansion coefficient as that of the metal matrix.

The upper punch 3 and the lower punch 4 may be made of any material having a hardness higher than that of the metal matrix. Further, in order to size a metal body having an uneven portion in the height direction, the same uneven portion may be provided on the upper punch 3 and the lower punch 4. Again,
The dimensions may be designed in the same manner as the mortar type, and it is preferable to select one having the same coefficient of thermal expansion as that of the metal matrix.

Next, the sizing step will be described. FIG. 2 is a diagram showing an example of the process. The mode of operation of the hot sizing machine is as follows.

(A) With the lower punch 4 lowered, a predetermined quantity of the metal matrix 8 is put into the introduction part 7 of the heated die 2.

(B) The upper punch 3 is lowered, and the sample is fitted into the correction section 6.

(C) When the sample comes into contact with the lower punch 4, it is held for a certain period of time.

(D) The upper punch 3 and the lower punch 4 are lifted to remove the mold and cool.

A metal matrix 8 is introduced into the introduction part 7 of the heated die 2
By putting in, the metal body is heated, and plastic deformation becomes possible. Therefore, the metal punch 8 can be pushed into the correction section 6 by lowering the upper punch 3, and sizing is performed by holding the metal punch 8 for a certain period of time. After sizing, the metal matrix 8 is removed from the mold by raising the lower punch 4. By cooling thereafter, a metal member having a predetermined dimensional accuracy can be obtained.

The hot sizing machine and the mode of operation of the present invention are not limited to those shown in FIGS. 1 and 2, and various modifications can be made as long as they satisfy the technical idea of the present invention. is there. For example, in order to prevent the sample from tilting, the lower punch may first be raised to the introduction portion, the sample may be placed thereon, and then the upper punch and the lower punch may be pushed into the die. Alternatively, the upper punch may be lowered to remove the sample from the lower side of the die. If the sample passes through the heated die, either the upper punch or the lower punch may be omitted. May be.

The mortar die is heated to 350 ° C. or above during sizing. If the die temperature is 350 ° C. or lower, the temperature will not be high enough to plastically deform the metal body, and the metal body will crack during sizing. The upper limit of the sizing temperature is not particularly set, but may be determined depending on the heat-resistant temperature of the die and economic efficiency. Practically, it is 1200 ° C or lower, preferably 900 ° C or lower.

Pressure may be applied when holding the metal form in the die. Pressurization enables more precise sizing. This is particularly effective when accuracy in the height direction is required. The pressure at this time is 15 ton / cm ² or less. If the pressure is too high, stress may be applied to the metal matrix to cause distortion, which may affect the magnetic properties. Further, the life of the die and the punch is shortened and the size of the apparatus becomes large. Therefore, it is better to apply the pressure as low as possible. Preferably 8 ton / cm ² or less, more preferably 6
It is ton / cm ² or less. The pressure may be applied from either the upper or lower punch direction, or from both directions. When pressurizing, both upper and lower punches are required.

The present invention can be applied to a metal member containing Fe and having good magnetic properties. In particular, Fe and S
i, Al, Ni, Co, and Cr can be added to be suitably used for a member having improved magnetic characteristics.

Si is preferably contained in an amount of 3 to 50 wt% in order to reduce Hc. If it is out of the above range, the decrease in Hc becomes insufficient.

Like Si, Al is preferably contained in an amount of 3 to 50 wt% in order to reduce Hc. If it is out of the above range, the decrease in Hc becomes insufficient.

Ni is preferably contained in an amount of 20 to 80 wt% in order to lower Hc and further improve μ. If it is less than the above range, the effect of addition is not sufficient, and if it exceeds the above range, Hc and μ are deteriorated.

Co is preferably contained in an amount of 40 to 60 wt% in order to improve Bs. B is less than the above range
The improvement of s is not sufficient, and when it exceeds the above range, Bs is lowered.

The corrosion resistance is improved by containing Cr. The content is preferably 12 to 25 wt%, and if it is less than the above range, the effect of addition is not sufficient, and if it exceeds the above range, the magnetic properties are deteriorated. When Cr is contained, N
Corrosion resistance can be further improved by containing i of 4.5 to 20.

These additional elements may be added alone or in combination of two or more.

The method for producing the metal matrix may be any conventional method. For example, a powder metallurgy method, a casting method and the like can be mentioned. After that, by performing sizing by the method of the present invention, it is possible to keep the dimensional accuracy within the target tolerance and reduce the dimensional variation. According to the method of the invention, especially for magnetic materials,
It is possible to perform sizing with high dimensional accuracy so that a metal magnetic material having a composition range with good magnetic properties can be used for a member having strict dimensional accuracy requirements.

[0042]

【Example】

(Example 1) Fe powder and Fe-50 wt% Si powder,
Fe-6.5 wt% Si was mixed. This mixed powder was molded into a toroidal shape with a molding pressure of 7 ton / cm ² using a mold. This molded body has a maximum set temperature of 135
The sample was fired in a tunnel furnace at 0 ° C. in an H ₂ atmosphere to obtain a metal form sample.

This sample was placed in a mold heated to 600 ° C. and held for 1 second without applying pressure for sizing. At this time, the number of samples was 30. As a result, the standard deviation of the inner and outer diameter dimensions of the sample was 12 μm. Also,
For all the samples, the difference between the maximum value and the minimum value was within 80 μm for both the inner and outer diameters.

Example 2 Using the same metal form as in Example 1, the metal mold was placed in a mold heated to 20 to 700 ° C., and then 6
Sizing was performed by applying a pressure of about 14 ton / cm ² for 1 second. 1-6 were produced. In addition, No. 7
Is a sample that was not sized. The number of samples was 30, respectively. Table 1 shows the standard deviation of the inner and outer diameters.

[0045]

[Table 1]

From Table 1, it can be seen that the standard deviation can be reduced by carrying out the sizing of the present invention. Also, N
o. In all samples 2 to 6, the difference between the maximum value and the minimum value was within 80 μm for both the inner and outer diameters. No. 3 outside the scope of the present invention. In No. 1, all samples were cracked during sizing. Moreover, by applying pressure during sizing, it became possible to reduce the strain in the height direction.

(Example 3) Fe powder and Fe-50 wt
% Al powder was mixed to be Fe-16 wt% Al. Mold this mixed powder into a toroidal shape with a pressure of 7
It was molded using a mold at ton / cm ² . This compact is fired in a tunnel furnace in a H ₂ atmosphere with a maximum set temperature of 1350 ° C.,
A metal form sample was obtained.

This sample was put in a mold heated to 350 to 700 ° C. and then sized by pressurizing at 6 to 14 ton / cm ² for 1 second. 8-12 were produced. In addition, No. No. 13 is a sample which was not sized. The number of samples was 30, respectively. Table 2 shows the standard deviation of the inner and outer diameters.

[0049]

[Table 2]

From Table 2, it is understood that the standard deviation can be reduced by carrying out the sizing of the present invention. Also, N
o. In all samples 8 to 12, the difference between the maximum value and the minimum value was within 80 μm for both the inner and outer diameters.

Example 4 Fe-50 wt% Ni powder was molded into a toroidal shape at a molding pressure of 7 ton / cm ² using a mold. This molded body has a maximum set temperature of 1350 ° C., H
_The sample was fired in a tunnel furnace with _two atmospheres to obtain a metal matrix sample.

This sample was put in a mold heated to 350 to 700 ° C. and then sized by pressurizing at 6 to 14 ton / cm ² for 1 second. 14-18 were produced. In addition, No. 19 is a sample which was not sized. The number of samples was 30, respectively. Table 3 shows the standard deviation of the inner and outer diameters.

[0053]

[Table 3]

From Table 3, it can be seen that the standard deviation can be reduced by carrying out the sizing of the present invention. Also, N
o. In all samples 14 to 18, the difference between the maximum value and the minimum value was 80 μm or less for both the inner and outer diameters.

(Example 5) Fe powder and Co powder were mixed with Fe-
It mixed so that it might become 50 wt% Co. This mixed powder was molded into a toroidal shape with a molding pressure of 7 ton / cm ² using a mold. This molded body has a maximum set temperature of 1350 ° C., H
_The sample was fired in a tunnel furnace with _two atmospheres to obtain a metal matrix sample.

This sample was put in a mold heated to 600 to 700 ° C. and then sized by pressurizing at 6 to 12 ton / cm ² for 1 second. 20-22 were produced. In addition, No. No. 23 is a sample which was not sized. The number of samples was 30, respectively. Table 4 shows the standard deviation of the inner and outer diameters.

[0057]

[Table 4]

From Table 4, it can be seen that the standard deviation can be reduced by carrying out the sizing of the present invention. Also, N
o. In all samples Nos. 20 to 22, the difference between the maximum value and the minimum value was 80 μm or less for both the inner and outer diameters.

(Example 6) Fe powder, Fe-50 wt% Al
Powder and Fe-50 wt% Si powder to Fe-6.5 wt% A
1-10 wt% Si was mixed. This mixed powder was molded into a toroidal shape with a molding pressure of 7 ton / cm ² using a mold. This molded body has a maximum set temperature of 1350
The sample was fired in a tunnel furnace in an atmosphere of H _{2 at 0} ° C. to obtain a metal matrix sample.

This sample was put in a mold heated to 600 to 700 ° C. and then sized by pressurizing at 6 to 12 ton / cm ² for 1 second. 24-26 were produced. In addition, No. No. 27 is a sample which was not sized. The number of samples was 30, respectively. Table 5 shows the standard deviation of the inner and outer diameters.

[0061]

[Table 5]

From Table 5, it is understood that the standard deviation can be reduced by carrying out the sizing of the present invention. Also, N
o. In all of Nos. 24 to 26, the difference between the maximum value and the minimum value was within 80 μm for both the inner and outer diameters.

As described above, the effects of the present invention are clear from Examples 1 to 6.

[0064]

Industrial Applicability The present invention provides a highly accurate sizing method capable of reducing the dimensional variation of a metal matrix and improving the yield. Further, unlike the conventional method, the cutting process is unnecessary, so that the cost can be reduced.
Further, the present invention is particularly applicable to a member manufactured by the conventional method and having good magnetic properties.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a hot sizing machine of the present invention.

FIG. 2 is a diagram showing an example of a hot sizing process of the present invention.

[Explanation of symbols]

 1 Hot sizing machine 2 Mortar type 3 Upper punch 4 Lower punch 5 Heating means

Front page continuation (72) Inventor Teruo Mori 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation

Claims (9)

[Claims] 1. A sizing method for a metal base body, which comprises inserting the metal base body into a mold heated to 350 ° C. or higher. 2. The metal mold is fitted into a heated mold and then pressurized at 15 ton / cm ² or less.
The sizing method described in. 3. The sizing method according to claim 1, wherein the metal matrix contains Fe. 4. The metal matrix has at least Si of 3 to 3.
The sizing method according to claim 3, wherein the content is 50 wt%. 5. The metal matrix contains at least Al of 3 to 3.
50 wt% is contained, The sizing method of Claim 3 or 4 characterized by the above-mentioned. 6. The metal matrix has at least Ni of 20 or less.
The sizing method according to any one of claims 3 to 5, characterized in that the content is -80 wt%. 7. The metal matrix contains at least 40 Co.
The sizing method according to any one of claims 3 to 6, wherein the sizing method comprises -60% by weight. 8. The metal matrix has at least 12 Cr.
25 wt% is contained, The sizing method of Claims 3-7 characterized by the above-mentioned. 9. The metal element body contains 12 to 25 wt% of Cr.
%, Ni of 4.5-20 wt% is contained, The sizing method of Claim 3 characterized by the above-mentioned.