JP3153066B2 - Sintered material with excellent machinability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered material having improved machinability and excellent machinability without decreasing hardness and strength.

[0002]

2. Description of the Related Art Sintered machine parts require no cutting process,
The economic effects such as material savings are great, and the degree of application in automobiles, precision machinery and household appliances has increased remarkably in recent years, but when the shape is complicated or high dimensional accuracy is required, etc. Is also applied,
Cutting is also required for sintered parts.

However, unlike a smelted material, a sintered machine component has interstitial holes during cutting, which causes intermittent cutting, and the holes act as a heat insulator to prevent heat conduction. As a result, the temperature of the cutting tool is increased, so that the life of the cutting tool is short, and improvement in machinability has been demanded.

Therefore, in order to improve the machinability of the sintered material,
Glass powder, talc and BN are added. For example, in the invention of a free-cutting sintered material disclosed in JP-A-63-93482, a non-metallic powder such as glass, boron nitride, talc, etc. is mixed with a metal powder and sintered to improve tool life and improve machinability. Has improved. As a paper in which glass powder, talc, and BN are added to a sintered material, "Improvement in machinability of composite alloy powder sintered material" (Transactions of the Japan Society of Mechanical Engineers, Tokai Branch, Mie Region, 92.7.
17． No. 923-2).

[0005] Further, US Pat. 5041158 (A
ug. 20, 1991), the adhesion wear is improved by adding talc (0.75 to 7.0%) in the sintered material, and the invention of the iron-based mixed powder disclosed in JP-A-1-255604 is disclosed. In this method, talc powder having an average particle size of 8 to 20 μm is mixed with an iron-based raw material powder to obtain a sintered machine part having excellent machinability while maintaining mechanical properties equivalent to those of conventional iron powder.

[0006]

However, when glass powder, talc, BN, etc., which are non-metallic materials, are added to the iron-based raw material powder as described above, the machinability is improved, but the hardness is reduced and the impact is reduced. There is a problem that the mechanical strength of the sintered material is deteriorated due to deterioration of the value.

The present invention has been made to solve the above-mentioned problems of a sintered material having improved machinability by adding a non-metallic material to an iron-based raw material powder. It is an object of the present invention to provide a sintered material excellent in machinability which can improve machinability without deteriorating mechanical properties such as the above.

[0008]

Means for Solving the Problems In order to solve the above problems, the present inventors have repeatedly studied the effects of adding various nonmetallic materials. As a result, one or more of sepiolite, attapulgite or zeolite was
3% by weight or less in total of at least one of sericite, talc or BN, or 0.5% by weight of at least one of sepiolite, attapulgite and at least one of talc and BN. The present invention has been newly found that machinability can be improved without deteriorating mechanical strength when the content is 1% by weight or less in total.

The grit of the first aspect of the present invention is that the sintered material contains at least one of sepiolite, attapulgite and zeolite in a total amount of 3% by weight or less. The sintered material excellent in machinability according to claim 2 of the present invention is one of sepiolite, attapulgite and zeolite.
The gist of the present invention is to contain at least 3% by weight of a total of at least one kind of sericite, talc, and BN. Further, the sintered material excellent in machinability according to claim 3 of the present invention contains at least 0.5% by weight of each of at least one of sepiolite and adapulgite and at least one of talc and BN, and a total of 1% by weight or less. It is assumed that it is contained.

[0010] Sepiolite (sepiolite) and attapulgite are dispersed in a base material and have the effect of improving machinability. The machinability improving effect increases as the content increases, but if the weight ratio exceeds 3%, problems such as adsorption of the added graphite powder during sintering occur, and the material properties deteriorate. In addition, there is an effect of suppressing deterioration of material properties due to the inclusion of talc or BN. Sepiolite and attapulgite are substances of the same composition, but the crystal structure of sepiolite is lamellar, whereas attapulgite is chain-like.

[0011] Sericite is also called sericite, and has the effect of dispersing in a substrate and improving machinability. However, the weight ratio is 3
%, The added graphite powder is adsorbed during sintering, for example, and the material properties are degraded.

Zeolite is also called zeolite and has the effect of dispersing in a matrix to improve machinability. The machinability improving effect increases as the content increases, but if the weight ratio exceeds 3%, problems such as adsorption of the added graphite powder during sintering occur, and the material properties deteriorate.

[0013] Talc is also referred to as talc, and when added alone, has the effect of dispersing in the substrate and improving machinability, but reduces material properties such as radial crushing strength. However, when it is added together with sepiolite and attapulgite, the deterioration of the material properties due to the addition of talc can be suppressed, and the effect of the suppression is large up to a content of 0.5% by weight.

When BN is added alone, BN is dispersed in the substrate and has the effect of improving machinability, but material properties such as radial crushing strength are reduced. However, when it is added together with sepiolite and attapulgite, a decrease in material properties can be suppressed until the content exceeds 0.5% by weight. Also, when one or more of sepiolite and attapulgite and one or more of talc and BN are contained in a total weight ratio exceeding 1%, material properties such as radial crushing strength are deteriorated. One or more of sepiolite, attapulgite, zeolite, or one or more of sepiolite, attapulgite, zeolite and one or more of sericite, talc, BN, or one or more of sepiolite, attapulgite, and two or more of talc, BN If the total is less than 0.01%, no significant effect can be obtained.

[0015]

The sintered material excellent in machinability according to the present invention comprises at least one of sepiolite, attapulgite and zeolite in a total amount of 3% by weight or less, or one or more of sepiolite, attapulgite and zeolite and further sericite, One or more of talc and BN are contained in a total of 3% by weight or less, or one or more of sepiolite and attapulgite and one or more of talc and BN are each contained in a content of 0.5% by weight or less and a total of 1% by weight or less. Therefore, machinability can be improved without lowering the hardness and strength of the sintered material.
Although the detailed action is unknown, it is considered that the crystal structure is a layered intercalation compound. When sepiolite or attapulgite is mixed and added with talc or BN, talc or B
Deterioration of material properties due to the addition of N is suppressed, and the effect of improving machinability is maintained. The cost of sepiolite, attapulgite, zeolite or sericite is lower than that of BN which is a conventional free-cutting component.

In the present invention, the content of one or more of sepiolite, attapulgite and zeolite is 3% by weight or less in total, or the content of one or two of sepiolite and zeolite and sericite is 3% by weight in total. The reason for this is that if these free-cutting components exceed 3%, the mechanical properties such as hardness and strength of the sintered material deteriorate.

[0017]

【Example】

(Example 1) An example of the present invention will be described in comparison with a comparative example to clarify the effects of the present invention. As raw material powder, commercially available pure iron powder, commercially available alloy steel powder (DISTALOY A
E, Fe-4Ni-1.5Cu-0.5Mo), and Co powder, Cu powder, sepiolite powder, sericite powder, zeolite powder, talc powder, BN powder, and intermetallic compounds of 150 μm or less, each having a particle size of 75 μm or less. FeMo
Powder, a natural graphite powder having a particle size of 25 μm or less and a lubricant zinc stearate powder are prepared, and these raw material powders are blended so as to have the compositions shown in Tables 1 to 5;
After the addition, mixing was performed by a powder mixing device.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

[Table 5]

Examples 1 to 7 shown in Table 1 were applied to pure iron powder under 2.
Example of the present invention in which sepiolite, sericite, and zeolite were added within the composition range of the present invention to a substance to which 0% Cu powder and 0.5% graphite powder were added, and Example 8 in Table 2
Nos. 14 to 14 show the present invention in which sepiolite, sericite and zeolite were added to pure iron powder to which 10% Co powder, 1.0% graphite powder and 10% FeMo powder were added, within the composition range of the present invention. Examples 15 to 21 in Table 3 are examples of the present invention in which sepiolite, sericite, and zeolite are added within the composition range of the present invention to alloy steel powder to which 0.3% of graphite powder is added. It is an example.

Comparative Example 1 in Table 4 has compositions corresponding to Examples 1 to 7 in Table 1, and Comparative Examples, Comparative Examples 2 and 3 in which sepiolite, sericite, zeolite, etc. were not added at all.
Is a comparative example in which sepiolite, sericite, zeolite and the like were not added at all in the composition corresponding to Examples 8 to 14 of Table 2, Comparative Example 3 was impregnated with Pb, and Comparative Example 4 was an operation of Table 3 This is a comparative example in which sepiolite, sericite, zeolite and the like were added at a composition corresponding to Examples 15 to 21.

In Comparative Examples 5 to 8, comparative examples in which sepiolite, sericite and zeolite were added to the compositions corresponding to the examples in Table 1 in amounts exceeding the composition range of the present invention were used.
12 is a comparative example in which sepiolite, sericite, and zeolite were added to the composition corresponding to the example in Table 2 above the composition range of the present invention, and Comparative Examples 13 to 16 were compositions having the composition corresponding to the example in Table 3. This is a comparative example in which sepiolite, sericite, and zeolite are added in the composition range of the present invention or more. Table 5
Comparative Examples 17 to 20 are comparative examples in which talc or BN was added to those having compositions corresponding to the examples in Table 2.

Various test piece compacts were formed from the mixed powder under a forming pressure of 700 MPa. The formed green compact was held at a temperature of 1493 K for 900 seconds in a reducing atmosphere to perform sintering. Note that, among the sintered test pieces, Comparative Example 3 was P
b Infiltration was performed.

Each of the obtained test pieces was measured for hardness, radial crushing strength and cutting resistance. The obtained results are shown in Tables 6 to 9.
In addition, the test conditions at the time of measuring cutting resistance are as shown below. Test specimen shape: outer diameter 30 mm, inner diameter 16 mm,
7mm thickness Test machine: Lathe Cutting tool (tip): cBN chip Cutting fluid: None Test conditions: Cutting speed 95m / min, feed 0.048mm / rev, depth of cut 0.5mm Measuring instrument: Cutting dynamometer

[0028]

[Table 6]

[0029]

[Table 7]

[0030]

[Table 8]

[0031]

[Table 9]

Examples 1 to 7, Comparative Example 1, and Examples 8 to 14
And Comparative Example 2 and Examples 15 to 21 and Comparative Example 4, it is clear that the examples of the present invention hardly change the material properties such as hardness and radial crushing strength or change to such a degree that there is no problem in use. Nevertheless, it has been found that the cutting resistance is greatly reduced by the effect of the present invention, and the reduction ratio is increased as the amount of addition increases within the specified range. In addition, there is no particularly significant difference in the free-cutting components added this time.

Conversely, when the free-cutting component is added in an amount exceeding 3% as in Comparative Examples 5 to 16, the cutting resistance is reduced as compared with Examples 1 to 21, but the material properties are lower than the cutting resistance. The drop is large. In addition, there is no particularly significant difference in the free-cutting components added this time.

Comparative Example 3 is a case where lead is impregnated in Comparative Example 2. As is apparent from comparison with Examples 8 to 14, the effect of the present invention is equivalent to that of impregnation with lead. There is. The reason why the material properties are improved is that voids peculiar to the sintered material are eliminated by impregnation with lead.

As is clear from Comparative Examples 17 and 19, when talc and BN are added alone, the cutting resistance does not decrease so much, but the hardness and the radial crushing strength decrease too much. In Comparative Examples 18 and 20, when talc and BN were added in the same amounts as in the Example, the diffusion of graphite was inhibited under the present production conditions, and it was difficult to obtain a structure having sufficient strength.

(Example 2) As raw material powder, commercially available pure iron powder, Co powder, sepiolite powder, talc powder, BN powder, intermetallic compound FeMo powder of 150 μm or less, and powder of 25 μm or less A natural graphite powder and a lubricant zinc stearate powder are prepared, and these raw material powders are blended so as to have the compositions shown in Tables 10 to 11, and after 0.8% of the lubricant is added, the mixture is mixed by a powder mixing device. Was done.

[0037]

[Table 10]

[0038]

[Table 11]

In Examples 22 to 27 of Table 10, sepiolite, talc, and BN were added to pure iron powder to which 10% Co powder, 1.0% graphite powder, and 10% FeMo powder were added. It is the Example of this invention added within the composition range of this invention. On the other hand, the comparative example in Table 11 is obtained by adding 10% of Co powder, 1.0% of graphite powder, and 10% of FeMo powder to pure iron powder, and Comparative Example 21 contains no sepiolite, talc and BN. Comparative Example 22
Is a sample in which only sepiolite is added by 0.30%, and Comparative Example 23 is a sample in which only talc is added by 0.30%.
In Comparative Example 24, only BN was added at 0.30%,
In Comparative Example 25, sepiolite, talc and BN were added in amounts of 0.
80% added.

Various test piece compacts were formed from the mixed powder under a forming pressure of 700 MPa. Holding the formed green compact in a reducing atmosphere at a temperature of 1493K for 1200 seconds,
Sintering was performed. Each of the obtained test pieces has a radial crushing strength and 2
The wear amount of the tool after cutting 00 times was measured, and the obtained results are shown in Table 12. In addition, the test conditions when measuring the tool wear amount are as follows. Test specimen shape: outer diameter 30 mm, inner diameter 16 mm,
Thickness 7mm Testing machine: Lathe Cutting tool (chip): cBN chip Cutting fluid: None Test condition: Cutting speed 95m / min, feed 0.048mm / rev, depth of cut 0.5mm Number of cuts: 200 times

[0041]

[Table 12] * 1: Relative display with Comparative Example 1 being 100. * 2: Under the present production conditions, the diffusion of graphite is inhibited, and it is difficult to obtain a tissue having sufficient strength.

As is clear from Examples 22, 24, and 26 and Comparative Example 21, despite the fact that there is almost no change in radial crushing strength, Examples 22, 24, and 26 have a tool wear amount of 74 due to the effect of the present invention. , 88, 84. In addition, Example 24 and Comparative Example 22 and Example 26 and Comparative Example 22 in which the added amount of sepiolite or talc was the same.
This shows that adding sepiolite in combination is more effective than adding it alone.

From Examples 22 and 23, Examples 24 and 25, Examples 26 and 27, and Comparative Examples 23 and 24, it can be seen that the effect of the present invention is increased by increasing the amount of addition.
When talc or BN is added alone, the tool wear amount is reduced, but the radial crushing strength is also reduced. As a result, it was found that the composite addition of sepiolite suppresses the deterioration of the material properties due to the addition of talc or BN, and the effect of improving machinability is maintained, thus confirming the effect of the present invention.

[0044]

As described above, the sintered material excellent in machinability according to the present invention is composed of sepiolite, attapulgite,
3% by weight or less in total of one or more zeolites, or one of sepiolite, attapulgite and zeolite
3% by weight or less in total of at least one kind and at least one kind of sericite, talc and BN, or 0.5% by weight or less each of at least one kind of sepiolite, atapulgite and at least one kind of talc and BN. Since 1% by weight or less is contained, machinability can be improved without lowering the hardness and strength of the sintered material. Although the detailed action is unknown, it is considered that the crystal structure is a layered intercalation compound. Further, when sepiolite and attapulgite are mixed and added with talc or BN, deterioration of material properties due to the addition of talc or BN is suppressed, and the effect of improving machinability is maintained.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Okajima 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Naomichi Akimoto 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation ( 72) Inventor Hideki Kato 5-1, Kurisuno Foxzuka, Yamashina-ku, Kyoto, Japan (72) Inventor Takashi Maeshima 5-1, Kurisino Foxzuka, Kyoto, Yamashina-ku, Kyoto, Japan Eiji Noto 5-1, Kurisuno Foxzuka, Yamashina-ku, Kyoto, Japan (72) Inventor Shuta Nishimura 5-1, Kurisuno Foxzuka, Yamashina-ku, Kyoto, Japan (58) Investigated field (Int .Cl. ⁷ , DB name) C22C 33/02 103 B22F 1/00

Claims (3)

(57) [Claims] 1. A sintered material excellent in machinability, characterized by containing at least 3% by weight of at least one of sepiolite, attapulgite and zeolite. 2. One or more of sepiolite, attapulgite and zeolite, and additionally sericite, talc and BN
A sintered material excellent in machinability, characterized by containing one or more of the following in a total of 3% by weight or less. 3. 0.5% by weight of each of at least one of sepiolite and attapulgite and at least one of talc and BN.
A sintered material excellent in machinability, characterized by containing not more than 1% by weight in total.