JPH04308005A - Production of metal molded with iron powder - Google Patents

Abstract

PURPOSE:To produce a high density and high strength low-cost metal molded body by adding a specified amt. of whiskers to iron powder obtd. by refining converter dust, kneading them with a small amt. of thermosetting resin and molding the resulting kneaded material. CONSTITUTION:Iron glain of 1-4 mm diameter or rectangular iron powder is added to iron powder obtd. by refining converter dust by 15-70%, they are kneaded with a small amt. of thermosetting resin and the resulting kneaded material is press-molded under >=2t/cm<2> pressure and heated to cure the resin. The iron powder obtd. by refining converter dust contains 5-30% grains of 10-74mum grain size, 50-70% grains of 74-149mum grain size and 5-20% grains of 149-500mum grain size. Proper amts. of resol and novolak are added as the thermosetting resin and the press-molded body is fired at 150-250 deg.C.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal molded body using as main raw materials refined iron powder from converter dust and granulated iron or rectangular iron powder (referred to as iron whiskers).

0002

[Prior Art] In recent years, methods such as lamination, forging, and casting have been used in the technical field of industrial machinery and metal parts, but these methods have problems in terms of formability, cost, and technology, and it is difficult to manufacture products using these methods. For example, as shown in Japanese Unexamined Patent Application Publication No. 2-141502, metal powder is used as the main raw material, filled into a mold with a desired shape, and press-formed for parts that are difficult to finish due to material or shape. , a method of manufacturing components by sintering was known.

[0003] In this method, waxes such as paraffin, carnauba wax, microcrystalline, and polyethylene wax, and organic substances such as acrylic resin, cellulose acetate, and polyvinyl alcohol are used as binders. This metal powder and one or more types of binder are used to knead them, fill a mold with the kneaded mixture, pressurize it with a press, etc., and then put it in a sintering furnace and heat it. After degreasing, the temperature was raised to about 1250°C and sintered. Additionally, a vacuum device was used in the furnace to prevent oxidation of the powder particles, and hydrogen gas, ammonia decomposition gas, etc. were used because a reducing atmosphere was required.

0004

[Problems to be Solved by the Invention] However, the method for manufacturing sintered metal products by the above method has the following problems. (2) Since sintering is performed at a high temperature of 1250°C and under vacuum, the equipment becomes large and complicated, leading to an increase in equipment costs. Furthermore, since it is a high-temperature treatment, it is necessary to perform degreasing, which complicates the treatment process. ■Since it is heated to high temperatures, it undergoes deformation due to shrinkage, resulting in poor dimensional accuracy. ■Since oxidation occurs during thermal degreasing and sintering, a vacuum or reducing atmosphere is required. ■Conventional powder metallurgy methods use reduced iron powder or electrolytic iron powder as raw materials, resulting in extremely high costs.

On the other hand, iron powder dust is thrown up during the operation of a converter in a steel mill, and if it is collected and refined, it becomes converter dust refined iron powder (OGP). The powder was not being used effectively and was being lumped into lumps and being reduced as a raw material. The present invention has been made in view of the above circumstances, and it is possible to produce a metal molded body using high density and low cost iron powder by effectively utilizing converter dust refined iron powder generated at a steelworks and by utilizing whiskers. The purpose is to provide a method.

[0006]

[Means for Solving the Problems] A method for producing a metal molded body using iron powder according to claim 1, which meets the above object, includes adding whiskers in an amount of 15 to 70% to converter dust refined iron powder, and then adding a small amount of whiskers to the refined iron powder. A thermosetting resin is added and kneaded, and then the kneaded iron powder is filled into a mold, press-molded under a pressure of 2 t/cm2 or more, and the molded product is heated and hardened.

[0007] In addition, the method for manufacturing a metal molded body using iron powder according to claim 2 includes polishing converter dust and reducing the particle size to 10 to 74 μm; 5 to 30%; 74 to 149 μm; 50%;
~70%; 149-500 μm; 15-7% of whiskers of 1-4 mm are added to the refined iron powder of converter dust of 5-20%.
0%, add appropriate amounts of resol and novolac, re-knead, then fill the kneaded iron powder into a mold, and 2t/c
The molded body is press-formed under a pressure of 150 m2 or more.
It is fired at ~250°C and is constructed to be particularly suitable for automobile counterweights. Here, it is preferable to use the whiskers as chips generated when sharpening the tip of the nail, but it may also be whiskers produced by processing other cutting chips or a wire or the like.

[0008]

[Operation] In the method for manufacturing a metal molded body using iron powder according to claim 1, after whiskers are added to converter dust refined iron powder in an amount of 15 to 70%, a small amount of thermosetting resin is added and kneaded. Since the kneaded iron powder is filled into a mold and press-molded under a pressure of 2 t/cm2 or more, a molded article having a predetermined shape is completed. Then, by heating this, the thermosetting resin is cured, but since it is sufficient to heat it to the curing temperature of the thermosetting resin, we decided to heat it at a relatively low temperature. This reduces deviations in product dimensions. Furthermore, since 15 to 70% of whiskers are mixed inside, they act as aggregates, increasing strength, further improving packing density, and increasing specific gravity.

[0009] In the method for manufacturing a metal molded body using iron powder according to claim 2, the particle size distribution of converter dust is
~74 μm; 5-30%, 74-149 μm; 50-7
0%; 149 to 500 μm; 5 to 20%, and 15 to 70% of whiskers are added to this, so the mixing ratio of coarse particles and fine particles is ideal, and the whiskers act as aggregates. , the strength increases and the specific gravity also increases. Here, in the present invention, the amount of whiskers added is 15
The reason for this is that if the amount of whiskers mixed in is less than 15% externally, the bulk specific gravity when formed into a counterweight will be relatively small, and the whiskers will be effective as aggregate. Therefore, no improvement in characteristic strength can be expected. If the amount of whiskers mixed is 70% or more in terms of external content, the bulk density of the counterweight will increase, but the strength and moldability of the molded product will be poor. Next, appropriate amounts of resol and novolac are mixed, with the resol being 0.5 to 2.0% by weight;
Novolak should preferably be in the range of 2.0 to 5.0% by weight; less than these amounts will result in insufficient strength after sintering, and more than these amounts will cause expansion and cracking during sintering. do. Furthermore, if the amount of resol added is too large, the dimensional accuracy will deteriorate, so it is preferable to reduce the amount. Next, it is put into a mold and pressure molded under a pressure of 2 t/cm2 or more, thereby producing a molded product with a high filling density. The molded article is then fired at a temperature of 150 to 250°C, thereby hardening the phenolic resin. In this case, if the temperature is too high, the phenolic resin will fly off, and if the temperature is too low, the phenolic resin will not harden.

0010

[Examples] Next, examples embodying the present invention will be explained to provide an understanding of the present invention. When gas generated during oxygen converter operation is treated in a non-combustible state, coarse dust collected is purified to produce converter dust refined iron powder (OGP). The composition of this converter dust refined iron powder is T・Fe>92%
It contains over 90% metallic iron. The particle size distribution is shown in Table 1, although there is some variation. Iron whiskers are mixed with this converter dust refined iron powder. These iron whiskers are whisker-shaped and have a minimum length of 1 mm x diameter of 0.5 mm.
mm, with a maximum length of about 4 mm x diameter of about 2 mm. Here, if the particle size (length) is 1 mm or less, the average particle size of the converter dust refined iron powder (≒100 to 120μ
Unless the whiskers are at least about 10 times larger than the whiskers (m), it will not be possible to form a dense metal molded body with a porosity close to zero. Further, when the weight of the product is small, it is ideal that the thickness is at least 1/2 to 1/3 of the thickness of the product. Therefore, since the thickness of the counterweight to be manufactured is approximately 8 mm at the thin part, the particle size is 4 mm.
It is necessary to use something smaller than mm.

[0011]

[Table 1]

A predetermined amount of phenol resin, which is an example of a thermosetting resin, is mixed as a binder into the above-mentioned converter dust refined iron powder. That is, approximately 1% by weight of liquid resol made with an alkali catalyst (formalin/phenol = 1 or more) was mixed into the mixture with respect to the mixture of converter dust refined iron powder and whiskers, and the mixture was uniformly kneaded. Thereafter, powdered novolak made with an acid catalyst (formalin/phenol = 1 or less) is added to the converter dust refined iron powder in an amount of about 3% by weight, and mixed uniformly. In this case, the order of addition is as the resol is a liquid and the novolak is a powder.
First, liquid resol is added and kneaded to the above-mentioned converter dust refined iron powder to uniformly cover the surface of the converter dust refined iron powder, and then powdered novolac is added and kneaded again, resulting in iron powder and whiskers. Novolac adheres evenly around the area.

[0013] Here, the mixing ratio of the whiskers to the converter dust refined iron powder is 15%, 20%, and 35%.
%, 70%, the mixture is 45 mm x 79 m
2t/cm2, 5t by filling into m x 13mm mold
Table 2 shows the results of molding at /cm2. The metal molded body is fired after deburring the green (using a file) and then using a firing furnace (including a drying furnace) in the atmosphere at a temperature of 150 to 25
Heat curing is carried out at 0°C (preferably 200°C). and,
This firing pattern is shown in FIG. As shown in FIG. 1, in the first period, water is removed from the resol, and then it is gradually heated to decompose and harden the novolak.

[0014]

[Table 2]

For comparison, Table 2 shows the strength of a metal molded body under the same conditions using only converter dust refined iron powder without whiskers mixed in. However, as shown in Table 2 and FIG. It can be seen that the addition of 20% is superior in terms of strength and density. Note that other thermosetting resins include urea resin, melamine resin, polyester resin, polyurethane, and epoxy resin, and it is also possible to use these.

[0016]

Effects of the Invention As is clear from the above description, in the method for manufacturing a metal molded body using iron powder according to claims 1 and 2, whiskers are used as raw materials in addition to converter dust refined iron powder. Since it is mixed in, it acts as an aggregate, increasing strength and density. In addition, in the manufacturing method, the resin is cured at a relatively low temperature, so the equipment cost is low, and the energy cost for heating is also low. Further, there is no need for vacuum equipment to prevent the mixed resin from oxidizing the iron powder, or equipment for a reducing atmosphere such as hydrogen gas or ammonia decomposition gas. Furthermore, since the heating temperature is low, the thermal shrinkage caused by the drop in room temperature is also small, and the dimensional accuracy is better than molded products made by conventional methods. In particular, as in the method for manufacturing a metal molded body using iron powder according to claim 2, a counterweight for vibration prevention of an automobile (for example, 44 x 78 x 12
When applied to a plate (consisting of a plate of mm), it is possible to manufacture a product with a long lifespan, which is lower in cost than before, and has sufficient strength and bulk specific gravity.

[Brief explanation of drawings]

FIG. 1 is a graph showing firing conditions for a metal molded body.

FIG. 2 is a graph showing whisker blending ratio and bulk specific gravity.

Claims (2)

[Claims] 1. After adding 15 to 70% of granular iron or rectangular iron powder to converter dust refined iron powder, adding and kneading a small amount of thermosetting resin, then filling the kneaded iron powder into a mold, 2t/c
1. A method for producing a metal molded body using iron powder, characterized in that the molded body is press-formed under a pressure of at least 2 m2, and the molded body is heated and hardened. [Claim 2] Converter dust is polished to a grain size of 10 to
74 μm; 5-30%, 74-149 μm; 50-70
%; 149-500 μm; Converter dust refined iron powder with a concentration of 5-20%, granular iron or rectangular iron powder of 1-4 mm 15-15%
70% of the powder was added, appropriate amounts of resol and novolac were added and kneaded again, and then the kneaded iron powder was filled into a mold and 2t//
The molded body is press-molded under a pressure of 15 cm2 or more.
A method for producing a metal molded body using iron powder fired at 0 to 250°C and particularly suitable for automobile counterweights.