JP3491864B2 - Metal sizing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for sizing a metal element. More specifically, the present invention relates to a sizing technique for a member used for a drive device such as a motor and requiring high dimensional accuracy. 2. Description of the Related Art Conventionally, a metal member has been manufactured by punching a steel sheet of a magnetic material such as an Fe—Si alloy or an Fe—Ni alloy into a predetermined shape. However, in the punching method, since the steel sheet can be punched only up to a thickness of about 1 mm, there are problems such as a limited shape and waste after the punching. Further, since hard metal materials are difficult to punch, the composition range of the material is limited. In the case of an Fe—Si alloy, the composition that can be punched is a Si content of up to about 3 wt%. More Si
When the amount is too large, the hardness becomes high and the toughness becomes weak. Therefore, when the thickness is about 500 μm, punching becomes impossible, and when the thickness is less than 500 μm, the steel plate is broken at the time of punching. For this reason, it has not been possible to form an Fe-6.5 wt% Si alloy, which has been conventionally known as a material having high magnetic properties, by punching. [0003] In order to obtain a member having high magnetic properties, a method is known in which materials are blended so as to have a predetermined composition, and then a molded body is obtained by a powder metallurgy method or a casting method. But,
In such a method, a dimensional change occurs during a manufacturing process such as sintering or melting, so that variations in product dimensions increase. Therefore, when actually manufacturing a product that requires high dimensional accuracy, it is necessary to sort all the products, which lowers the yield. Further, in order to increase the dimensional accuracy, it is necessary to perform cutting after firing. However, although high dimensional accuracy can be achieved by cutting, there is a problem as a practical means due to cost and time. [0004] Conventionally, with respect to Fe members, a so-called cold sizing method has been performed in which a metal is deformed into a mold having a desired shape at room temperature by utilizing the plastic deformability of the metal to correct the shape. This method is effective for metals such as Fe which are highly plastically deformable at room temperature. However, in the case of Fe alloy materials to which other elements are added in order to improve magnetic properties, the hardness becomes high, and However, since the plastic deformation does not occur in the sizing, there is a drawback that the material is broken during cold sizing. Further, Japanese Patent Publication No. 5-35203 discloses F
A method of manufacturing a high-density, high-strength, and high-precision spur gear in which e-alloy is subjected to precision die forging by warm forging, and the root bending strength is improved by fine-graining treatment is disclosed. Materials having composition ranges described in the gazette are not intended to improve magnetic properties. As described above, in the above-mentioned conventional method, it is difficult to form a metal material having good magnetic properties with high dimensional accuracy because of its high hardness. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for sizing a metal magnetic material having a good magnetic property, particularly an Fe alloy, with high yield, low cost, and high dimensional accuracy. [0007] Such an object is achieved by the following inventions (1) to (9). (1) A method for sizing a metal element, wherein the metal element is inserted into a mold heated to 350 ° C. or higher. (2) The sizing method according to (1), wherein the metal mold is inserted 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 form contains Fe. (4) The metal element is at least Si
The sizing method according to (3), wherein 3 to 50% by weight is contained. (5) The metal element is at least Al
The sizing method according to (3) or (4), wherein 3 to 50 wt% is contained. (6) The metal element is at least Ni
(3)-characterized by containing from 20 to 80 wt% of
The sizing method according to (5). (7) The metal element is at least Co.
(3)-characterized by containing from 40 to 60% by weight of
The sizing method according to (6). (8) The metal element is at least Cr
(3)-characterized by containing from 12 to 25 wt% of
The sizing method according to (7). (9) The metal element comprises 12 to 2 Cr.
The sizing method according to (3), wherein 5% by weight and 4.5 to 20% by weight of Ni are contained. DESCRIPTION OF THE PREFERRED EMBODIMENTS By heating a metal to a certain temperature or higher, plastic deformation can be performed at a relatively low pressure. The present invention provides a sizing method capable of reducing the dimensional variation and improving the yield by utilizing the characteristics. 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. FIG. 1 shows an example of a hot sizing machine used in the present invention. 1 is a hot sizing machine used in the present invention. The hot sizing machine 1 includes a sizing die (a die 2, an upper punch 3, and a lower punch 4), and a heating unit 5. The die 2 has a straightening portion 6 for straightening a metal element formed by an arbitrary method to a desired size. It is preferable that the introduction section 7 of the correction section 6 is made large so that the correction section 6 can enter even if the shape of the metal element sample varies to some extent.
The mortar 2 is provided with a heating means 5. The heating of the mortar mold 2 may be performed by an appropriate method such as resistance heating, high-frequency induction heating, and condensing heating. The material of the mortar 2 may have a higher hardness than the metal element to be sized, but preferably has a high thermal conductivity in order to uniformly and quickly heat the mortar. Specifically, carbide (WC-Co), cermet, or the like is used. When designing the dimensions of the sizing mold,
As the temperature rises, thermal expansion and contraction must be taken into account. If the metal expansion sample to be sized and the mold have the same thermal expansion coefficient, even if the mold expands at a certain temperature, the sample expands in the same way and shrinks at the same rate in the cooling process, You can design the mold to the exact dimensions you want. However, when the coefficient of thermal expansion between the mold and the sample is different, the dimensions must be designed taking this difference into account. For example, when the coefficients of thermal expansion of the mortar and the metal element sample are respectively α ₁ and α ₂ , the mold diameter is A (mm), and the sizing temperature is T (° C.), the sample size after cooling is A × T × (α ₂ −α ₁ ) (mm) smaller than the mortar size.
For this reason, it is necessary to design the mortar mold to be larger than desired dimensions by the above-described amount. For these reasons, it is preferable to use a die having the same thermal expansion coefficient as the metal element. The upper punch 3 and the lower punch 4 may be of any material as long as the material has a higher hardness than the metal element. Further, in order to size a metal body having an uneven portion in the height direction, the upper punch 3 and the lower punch 4 may be provided with the same uneven portion. Again,
It is sufficient to design the dimensions in the same manner as in the case of the mortar, and it is preferable to select one having the same thermal expansion coefficient as that of the metal element. Next, the sizing step will be described. FIG. 2 is a diagram showing an example of the process. The operation of the hot sizing machine is as follows. (A) With the lower punch 4 lowered, an arbitrarily determined number of metal elements 8 are put into the inlet 7 of the heated die 2. (B) Lower the upper punch 3 and fit the sample into the correction section 6. (C) When the sample comes into contact with the lower punch 4, the sample is held for a certain time. (D) The upper punch 3 is raised, and the lower punch 4 is raised to remove the mold and cool. The metal mold 8 is inserted into the introduction portion 7 of the heated die 2.
, The metal element body is heated and plastic deformation becomes possible. For this reason, by lowering the upper punch 3, the metal element 8 can be pushed into the straightening unit 6, and sizing is performed by holding it for a certain time. After sizing, the metal body 8 is released by raising the lower punch 4. Thereafter, by cooling, 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 be first raised to the introduction portion, the sample may be placed on the lower punch, and then pushed into the die together with the upper punch. Alternatively, the upper punch may be lowered to remove the sample from the lower part of the mortar. If the sample passes through the heated mortar, it is not necessary to provide either the upper or lower punch. You may. At the time of sizing, the mortar is heated to 350 ° C. or higher. If the mortar temperature is 350 ° C. or lower, the temperature does not reach a level at which the metal element can be sufficiently plastically deformed, and the metal element is broken during sizing. The upper limit of the sizing temperature is not particularly set, but may be determined based on the heat-resistant temperature of the mortar or the economic efficiency. Practically, it is 1200 ° C. or lower, preferably 900 ° C. or lower. Pressure may be applied when the metal element is held in the die. By applying pressure, more precise sizing becomes possible. 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, the metal element may be stressed, causing distortion and affecting magnetic properties. Further, since the life of the mortar and the punch is shortened and the apparatus becomes large-scale, it is better to apply the pressure as low as possible. It is preferably 8 ton / cm ² or less, more preferably 6 ton / cm ² or less.
ton / cm ² or less. Pressing may be performed from either direction of the upper and lower punches, or may be performed from both directions. When applying pressure, 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, S
i, Al, Ni, Co, and Cr can be added to a member having improved magnetic properties to be suitably used. Si is preferably contained in an amount of 3 to 50% by weight to reduce Hc. If it is outside the above range, Hc will not be sufficiently reduced. Al is preferably contained in an amount of 3 to 50% by weight to reduce Hc similarly to Si. If it is outside the above range, Hc will not be sufficiently reduced. Ni is preferably contained in an amount of 20 to 80% by weight 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 deteriorate. Co is preferably contained in an amount of 40 to 60% by weight to improve Bs. If it is less than the above range, B
When s is not sufficiently improved, and exceeds the above range, Bs decreases. The inclusion of Cr improves the corrosion resistance. The content is preferably 12 to 25% by weight. If the content is less than the above range, the effect of addition is not sufficient, and if the content exceeds the above range, the magnetic properties deteriorate. When Cr is contained, N
By containing 4.5 to 20 of i, the corrosion resistance can be further improved. These additional elements may be added alone or in combination of two or more. The manufacturing method of the metal element body may be any conventional method. For example, a powder metallurgy method, a casting method and the like can be mentioned. Thereafter, by performing sizing according to the method of the present invention, dimensional accuracy can be kept within the target tolerance, and dimensional variation can be reduced. According to the method of the present invention, especially for magnetic materials,
It is possible to size a metal magnetic body having a composition range with good magnetic properties with high dimensional accuracy so that it can be used for a member requiring strict dimensional accuracy. EXAMPLES Example 1 Fe powder and Fe-50 wt% Si powder were
It mixed so that it might become Fe-6.5wt% Si. This mixed powder was molded using a mold at a molding pressure of 7 ton / cm ² so as to have a toroidal shape. This molded body is set to a maximum set temperature of 135.
It was fired in a tunnel furnace at 0 ° C. and H ₂ atmosphere to obtain a metal element sample. The sample was placed in a mold heated to 600 ° C., and was sized by holding it for 1 second without applying pressure. At this time, the number of samples was 30. As a result, the standard deviation of the inner and outer diameters of the sample was 12 μm. Also,
For all the samples, the difference between the maximum value and the minimum value in both the inner and outer diameters was within 80 μm. Example 2 The same metal element as in Example 1 was placed in a mold heated to 20 to 700 ° C.
Sizing was performed by applying a pressure of 1 to 14 ton / cm ² for 1 second. 1 to 6 were produced. In addition, No. 7
Is a sample not subjected to sizing. The number of samples was 30 each. Table 1 shows the standard deviation of the inner and outer diameters. [Table 1] Table 1 shows that the standard deviation can be reduced by sizing according to the present invention. Also, N
o. In all of the samples 2 to 6, the difference between the maximum value and the minimum value was 80 μm or less for both the inner and outer diameters. No. out of the scope of the present invention. In No. 1, all the samples cracked during sizing. In addition, by applying pressure during sizing, distortion in the height direction can be reduced. The following is an example of the structure of the first embodiment. As described above, the effects of the present invention are clear from Examples 1 and 2 . The present invention provides a highly accurate sizing method which can reduce the dimensional variation of the metal element and improve the yield. Further, since cutting is not required as in the conventional method, cost can be reduced.
Further, the present invention is particularly applicable to members having good magnetic properties manufactured by a conventional method.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an example of a hot sizing machine of the present invention. FIG. 2 is a diagram illustrating an example of a hot sizing step of the present invention. [Description of Signs] 1 hot sizing machine 2 mortar mold 3 upper punch 4 lower punch 5 heating means

──────────────────────────────────────────────────続 き Continuing on the front page (51) Int.Cl. ⁷ Identification symbol FI // B30B 9/00 B30B 9/00 A (72) Inventor Teruo Mori TDK Corp. 1-13-1 Nihonbashi, Chuo-ku, Tokyo JP-A-5-179306 (JP, A) JP-A-5-179305 (JP, A) JP-A-5-78703 (JP, A) JP-A-63-190102 (JP, A) JP-A-62-103343 (JP, A) JP-A-57-104601 (JP, A) JP-A-47-22308 (JP, A) JP-A-57-92105 (JP, A) JP-A 55-104 128504 (JP, A) JP-A-5-255708 (JP, A) Table 2000-509440 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21J 1/00-13 / 14 B21J 17/00-19/04 B21K 1/00-31/00 B22F 1/00-8/00 C22C 1/04-1/05 C22C 33/02 C22C 38/00 303 C22C 38/40

Claims (1)

(57) [Claims] [Claim 1] Consisting only of iron and silicon, and having a silicon content of
Comprises 3 to 50% by weight of a sintered metal form,
Inserted into a mold heated to 350 ° C or more and 900 ° C or less,
A method for sizing a metal element, comprising applying a pressure of 5 ton / cm ² or less.