JPH01306543A - Wire for dot printer and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture the title wire at low cost by adding the hard fine grains of TiN, VC, etc., to high-carbon alloy iron powder having specific compsn., kneading the mixture with a specific organic binder, thereafter extruding it into the wire shape, to debindering and to vacuum sintering. CONSTITUTION:5-15wt.% TiN as hard fine grains having <=3mum grain size is, independently or in the compound with the fine grains of VC, added to the fine powder having 1-10mum grain size of high-carbon high alloy iron contg. the compsn. constituted of, by weight, 2.5-3.1% C, <2.0% Si, <1.5% Mn, 3-10% Cr, >3.0% W, >3.0% Mo (where 20-30% W+2Mo is regulated), 2-12% V, 2-12% Co and the balance Fe, and they are mixed. An organic binder such as methylcellulose and a water-soluble binder contg. 1.0-10wt.pts. glycerin, wax emulsion, stearic acid emulsion, etc., are kneaded into 100wt.pts. above mixture. The resultant is extruded into the bar shape or wire shape, is debindered, is thereafter sintered in vacuum and is furthermore subjected to wire drawing, by which the wire for a dot printer can be manufactured by a simple process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a dot printer wire and a method for manufacturing the same.

[Conventional technology]

Recently, powdered high-speed tool steel has been widely used for dot printer wire. The manufacturing method is to can the raw material powder and use hot isostatic pressing (hereinafter referred to as HIP).
After being sintered and consolidated, it is forged.

By rolling, it is made into a round wire rod with a diameter of about 6 nm, for example.

By repeating this many times of wire drawing and an annealing step between these wire drawing steps, the desired diameter of 0.3 mm is achieved.
It is processed to a certain degree.

On the other hand, the present inventors have developed a technique for forming thin wires by mixing a certain type of binder into metal powder to form a plastic kneaded body using an extrusion molding and sintering method ( Special application 1986-168 + 60 Gin).

[Problem to be solved by the invention]

The conventional manufacturing method of wire for dot printers using the canning-HIP method has the problem that many processing steps are required from raw metal powder to finishing the final product, and the metal used is However, it was limited to materials that could be easily plastically worked, and did not provide sufficient required performance.

An object of the present invention is to provide a dot printer wire that satisfies higher performance requirements by applying metal powder extrusion technology, and a method for manufacturing these wires from a wide range of materials at low cost.

[Means to solve the problem]

Claim 1 of the present invention is that the conventional canning-HIP method is capable of producing a highly alloyed material that is difficult or impossible to manufacture due to its insufficient workability, thereby providing required properties such as excellent wear resistance. This is a dot printer wire. That is, the alloying element contains at least C2.5 to C3.
1%, Si 2% or less, Mn 1.5% or less, Cr 3-1
05, W3% or more, Mo3% or more, however, W + 2 M
o 20-305, V 2-12%, Co2-12
% of machinability, high wear resistance, high alloy high speed tool steel, or additional hard fine particles added thereto, at a weight ratio of 2 to 1.
This wire for dot printers is characterized by being made of a material in which 2% is uniformly dispersed.

Claims 3 to 6 of the present invention provide a plastic kneaded body by mixing an organic binder with an alloy steel powder having a particle size of 1Oμ01 or less or a raw material powder to which hard fine particles are added, and forming the plastic kneaded body into a rod or a plastic kneaded body by an extrusion method. After forming into a linear shape, the formed body is removed from the binder and vacuum sintered to substantially achieve true density,
This method of manufacturing wire for a dot printer is characterized by further adding plastic working such as drawing.

The present invention applies the technique of the above application to a wire for dot printers, which requires high abrasion resistance and hence high hardness, and is thin in diameter (approximately 0.31110 mm), and is suitable for applications where toughness against breakage and reliability are particularly required. This is a further improvement.

Cemented carbide wire for dot printers is manufactured by extrusion molding and sintering, and is used when particularly high wear resistance is required. Have difficulty. Therefore, there is no suitable method for finishing the wire diameter other than polishing, and polishing the brackets requires extreme care because the wire diameter is very thin at approximately 0.3 mmφ and the material is brittle, and it is expensive. Become.

In use, the wire of the present invention can be heat-treated by quenching and tempering to give it hardness and wear resistance that rival those of the cemented carbide mentioned above, but in manufacturing, it is manufactured in an annealed state, so it cannot be used for drawing or other purposes. It can be plastically worked, and particularly by drawing, it can provide high diameter accuracy, which is very advantageous compared to cemented carbide in the production of wires for dot printers.

The first aspect of the present invention is that, as described above, it is possible to directly obtain a small diameter wire by extrusion and sintering, and to apply a minimum amount of plastic working such as drawing to this wire in an annealed state. For this reason, some deterioration in workability is acceptable, and therefore high alloy materials are used to improve the performance of the product. Conventionally, such high alloy materials have not been realized as wires for 1-t printers.

The alloy steel powder used in the manufacturing method of the present invention has a particle size of 10 μm or less. If the particle size exceeds 10 μm, the sintering properties will decrease, and the breakage resistance of small-diameter products will decrease.

Further, in order to ensure binder removal properties, it is desirable that the particle size of the alloy steel powder be 1 μm or more.

The reason for adding each alloying element and the reason for limiting the numerical value will be described below.

The wire material of the present invention has a hardness of 1iRc70 in the product state.
A high hardness of -73 (I11/Gen 1030-1220) can be obtained, and in addition, carbide exists in a hardened state at 30 VO 1% or more, and in addition to high hardness, it is possible to achieve extremely high wear resistance due to carbide. It is.

For this purpose, W 3% or more, M
o3% or more, W + 2 Mo 20-305, V
It is necessary to contain 2-12%. W and Mo combine with C to form M and C type carbides, some of which solidly dissolve in the matrix and increase tempering hardness, while others remain as carbides and provide wear resistance. . W3% or more.

HRC70 unless Mo3% or more, W+2Mo205 or more
It is not possible to obtain a tempering hardness higher than W + 2 M
If o exceeds 305, the shape of the carbide becomes amorphous, making it impossible to obtain the necessary mechanical properties. M6C generated at this time
In order to increase the hardness of the type carbide, W is 7 to 12%,
Mo is preferably in a range of 5 to 9%.

(2) combines with carbon to form a hard MC type carbide. Although this carbide does not contribute much to improving tempering hardness, it significantly contributes to improving wear resistance. In order to obtain sufficient wear resistance, a minimum of 2% is required as (2), and if it exceeds 12%, the material becomes brittle. Moreover, it is desirably 4% or more.

Cr requires 3 to 105. Cr exists in the matrix and as a carbide, but it is highly effective in improving hardenability by being dissolved in the matrix. In addition, in the case of screwdriver (-wire), the corrosion and abrasion caused by the chemical substances contained in the ink is large, so it is necessary to add as much as possible to provide corrosion resistance.However,
Addition of more than 105 lowers the tempering hardness by 3%.
If it is less than 3, hardenability cannot be obtained, so it is set in the range of 3 to 105. Usually 7% or less is sufficient.

C combines with Cr, W, Mo, and V, and it is necessary to add the theoretical amount of carbon required to form a carbide and the amount of solid solution in the matrix. In the composition of the present invention, 2.5 to 3
．． 1% addition is required.

Co mainly dissolves in the matrix and contributes to improving the tempering hardness. 11 To obtain a hardness of RC70 or higher, at least 2% is necessary, and 4% or more is desirable.

On the other hand, even if it is added in an amount exceeding 12%, there is no effect commensurate with the amount added in improving tempering hardness.

Si is added as a deoxidizing element in an amount of 2% or less. Usually 1z
The following amount of addition may be sufficient, but if the addition is further increased, the carbide precipitation reaction can be promoted.

In addition, Si has the effect of strengthening the base, improving the yield strength of the wire for dot printers, and increasing the fatigue limit. However, addition of a large amount leads to deterioration of toughness and causes wire breakage for dot printers, so it is limited to 2% or less.

Mn is mainly added as a deoxidizing agent and a desulfurizing agent.

However, if added in a large amount, the toughness will deteriorate and the workability will deteriorate, so it is necessary to limit the amount to 1.3 or less.

In addition to the above-mentioned elements, the dot printer wire of the present invention may contain 2% or less Ni, 1% or less N, etc., as appropriate. Of these, N has the effect of increasing the hardness of the matrix and the effect of forming a solid solution in the MC carbide to form an MCN type carbonitride, thereby increasing the welding resistance. However, the amount that can be contained industrially is only 1%.
Therefore, it was limited to 1%. In addition, in high-speed tool steel, normally 0.05% or less of NO is contained as an impurity.

It is also effective to add hard compound fine particles as a raw material for extrusion molding. Below, TiN and VC, which have somewhat better effects, will be described.

T i N is mixed and added as a single particle separately from the alloy powder. The compound reacts with the MC type carbide during sintering,
Most of it exists in the form of (Ti, V) (CN), which is effective in improving seizure resistance and refining the sintered structure. If it is less than 5%, these effects will be small, and if it is added in excess of 15%, the material will tend to become brittle.

The carbonitride particles after sintering cannot be made finer than the particle size of the raw material powder. Therefore, the particle size of 1" i N is set to 3 μm.
It is necessary to regulate the following. When it exceeds 3 μm, coarse carbonitride particles are generated, which deteriorates mechanical properties.

VC reacts with TiN to form mainly (Ti, V) (CN
). As mentioned above, MC type carbide in steel is also T.
Although jN reacts, it is desirable to add VC in an amount of 2 parts by weight or less together in advance, since this significantly improves the sinterability of TiN.

Other desirable hard particles include Ti and V.

Examples include nitrides, carbides, and carbonitrides of Zr, Nb, Hf, and T'a, and it is desirable to add one or more of these in a weight ratio of 2 to 105. 2% less hη
If it exceeds 12%, the effect will be saturated and the stiffness and toughness will be significantly reduced.

Next, the desirable addition range of the binder and the like in the second aspect of the present invention will be explained.

In the present invention, the water-soluble organic binder contains raw material powder 10
It is desirable that the amount is 1.0 to 10 parts by weight relative to 0 parts by weight. If it is less than 1.0 parts by weight, sufficient moldability and green strength cannot be obtained, and if it exceeds 10 parts by weight, the green strength is saturated and economical efficiency is lowered, and the binder removal property and the density after binder removal are reduced. descend. Specifically, methylcellulose is desirable, and in this case, it is desirable to use 1.0 to 7.0 parts by weight.

It is desirable that the amount of water be 5.0 to 15.0 parts by weight.

If it is less than 5.0 parts by weight, the fluidity necessary for molding cannot be obtained,
On the other hand, if it exceeds 15.0 parts by weight, the shape retention property is lost and molding becomes impossible. Glycerin may be added if necessary to improve the plasticity of the kneaded product, but if it is added in excess of 9.0 parts by weight, moldability will decrease. If necessary, wax emulsion and stearic acid emulsion can be added as dispersants and plasticizers to improve moldability, but if they are added in excess of 5 parts by weight, the binder removal properties and density after binder removal will decrease. do.

〔Example〕

Example I C1,305, Si 0.52%, Mn 0.46%, C
r 4.2%, W6.5%, Mo5.2%, V3.
A water atomized pre-alloyed powder consisting of 1% Co, 7.9% Co, the balance iron and unavoidable impurities was prepared. The average particle size was 30μm and the 02 content was 2000ρρm. The powder was crushed in an attritor and then classified to have an average particle size of 5 μm.
A powder with an apparent density of 405 was obtained. For 100 parts by weight of this powder, 0.2 parts by weight of graphite powder and methylcellulose (
4.0 parts by weight of commercial product name 5M400) was added and mixed for 12 hours using a V-type blender.

After adding 6.0 parts by weight of water, 2.0 parts by weight of wax emulsion, 1.0 parts by weight of stearic acid emulsion, and 1.0 parts by weight of glycerin to the above mixed powder, they were mixed in a Henschel mixer, and then transferred to a three-roll mill. The mixture was kneaded three times.

This kneaded body was molded into a round bar shape of φ1.2 using a screw extruder. The molded body was dried with hot air at 80° C. for 12 hours. The green density of the molded body was 605. This dried body was heated to 600°C at a heating rate of 50°C/llr in an H2 atmosphere to remove the binder, then switched to a vacuum atmosphere and continuously heated at a rate of 100°C/11r for 9
The temperature was raised to and maintained at 00°C, and then cooled.

The binder-free body is in a pre-sintered state and has sufficient strength for handling, and the C and 02 contents are C1 and C7, respectively.
2%, 0.5100 ppm.

This binder-free body was vacuum sintered at 10-' torr and 1250°C. The sintered body is C1.29%, 0.50pp.
No. 11, the density was 8.01 g/ffl, which was the true density.

After the surface of the sintered body was polished, it was subjected to cold wire drawing.

Finished as wire material for dot printers with a diameter of 0.30+m.

Example 2 C1.9%, Si 0.52%, Mn 0.505,
Cr4.6%, W 10.2%, Mo 8.05, V
A water atomized pre-alloyed powder consisting of 5.1% Co, 10.3% Co, the balance iron and unavoidable impurities was prepared. The average particle size was 25 μm and the 0□ content was 2500 ppm. After grinding the powder for 8 hours using a vibrating mill,
Classified to 10μm or less, average particle size 7μm, apparent density 4
A 2% powder was obtained.

For 100 parts by weight of this powder, 0.1 parts by weight of graphite powder and 4 parts by weight of methylcellulose (commercial product name 60Sh4000) were added.
．． 0 parts by weight was added and mixed for 12 hours using a ■ type blender.

After adding 8.0 parts by weight of water and 1 part by weight of glycerin to the above mixed powder, they were mixed in a Henschel mixer and then transferred to a continuous kneader.
It was kneaded.

The above mixed wire body was made into a φ0.6 piece using a plunger type extruder.
It was molded into a round bar shape of m in diameter, dried, binder removed, and sintered in the same manner as in Example 1. Here, the C and O2 contents of the binder-free body were C2.42% and 0.25700 ppm, respectively, and the sintered body had C1.94% and 0.242 ppm. The above sintered body was subjected to HIP treatment. The density after HIP was 8.09 g/cJ, which was the true density.

The sintered body with a diameter of 0.49 mm obtained above was subjected to drawing finishing to produce a wire material for a dot printer with a diameter of 0.30 nn.

Example 3 C2, 98%, S i O, /15%-Mn 0.39
%, Cr 4.5%.

W], 00.05Mo8.2%, V8.2%, C
A water atomized prealloyed powder was prepared consisting of 8.7% o, the balance iron and unavoidable impurities. Average particle size is 20μ
The 02 content was 3100 ppm. The powder was crushed in an attritor at 300 rpm for 5 hours and then classified to IO μm or less, resulting in a powder with an average particle size of 6 μm and an apparent density of 41%. 3 μm for 100 parts by weight of this powder
The following 9 parts by weight of TiN powder, 1.0 parts by weight of VC powder, and 5 parts by weight of methylcellulose (commercial product name 5M1500) were added and mixed in a V-type blender for 24 hours.

After adding 7.5 parts by weight of water, 0.5 parts by weight of glycerin, and 1.0 parts by weight of stearic acid emulsion to the above mixed powder, they were mixed in a Henschel mixer and kneaded by passing through a three-roll mill five times.

This kneaded body was molded into a round bar shape of φ0.4 using a screw extruder. After drying the molded body in vacuum, the temperature was raised to 500°C at 100°C/fir in an N2 atmosphere.

The binder was removed. This binder body is C3,31
%, 0, 4800 ppm.

When the binder-free body was vacuum sintered at 10-' torr and 1240°C, the sintered body had a diameter of 0.32 nm and a C2
, 91%, 0, 521 ppm density 7.72 g/a
J is the true density.

The above φ0.32+a sintered wire material is finished and φ0.32+a is finished.
I made wire for a 30a+ dot printer.

Example 4 The dot printer wire material manufactured in Example 1.2.3 and the dot printer wire material (conventional material) processed by the conventional method using powdered high-speed steel with the same composition as in Example 1 were each processed under appropriate conditions. Table 1 shows a comparison of the characteristic values after quenching and tempering heat treatment with those of cemented carbide.

From Table 1, it can be seen that Examples 1 and 2.3 all have bending strengths equal to or higher than conventional materials, and can be used satisfactorily as wires for dot printers.

In addition, Examples 2 and 3 far exceed conventional materials in hardness, and in particular Example 3, which is the first invention of the present application, has high hardness and can be expected to have high wear resistance.

〔Effect of the invention〕

Claims (1)

[Claims] 1. At least C 2.5 to 3 in weight ratio as an alloying element
．． 1%, Si2% or less, Mn1.5% or less, Cr3-1
0%, W3% or more, Mo3% or more, however, W+2Mo20
Difficult-to-work, highly wear-resistant, high-alloy high-speed tool steel containing ~30%, V2 ~12%, and Co2 ~12%, or 2~12% by weight of hard fine particles added to it, uniformly dispersed. Wire for dot printers characterized by being made of a material made of 2 Weight ratio: C 2.5-3.1%, Si 2.05 or less, Mn 1.5% or less, Cr 3-7%, W 7% or more, Mo
5% or more, however, W+2Mo20-30%, V4-12%
, Co4-12%, N1% or less, Ti compound fine particles 12
The wire for a dot printer according to claim 1, characterized in that the wire is made of a material consisting of % or less. 3. Mix an organic binder with alloy steel powder with a grain size of 10 μm or less or a raw material powder with hard fine particles added thereto to form a plastic kneaded body, and after molding this into a rod or wire shape by extrusion molding, the molded body is A method for manufacturing a wire for a dot printer, which comprises removing the binder, vacuum sintering the wire to substantially achieve true density, and further adding plastic working such as drawing. 4. The organic binder is water-soluble, and the binder content excluding water is 1.0 to 10.0 parts by weight, and the water content is 5.0 to 15.0 parts by weight, relative to 100 parts by weight of the raw material powder. The method for manufacturing a dot printer wire according to claim 3. 5 The binder content excluding water is 1.0 to 7.0 parts by weight of methylcellulose or 9 parts of glycerin as a plasticizer added to this if necessary, per 100 parts by weight of the raw material powder.
．． 0 parts by weight or less, wax emulsion as a dispersant or lubricant, 5 parts by weight or less, stearic acid emulsion 5 parts by weight or less
5. The method for manufacturing a dot printer wire according to claim 4, characterized in that the wire is made of one or more kinds below the weight part. 6 Hard particles are TiN of 3 μm or less alone or 3
6. The method for manufacturing a wire for a dot printer according to claim 3, wherein the amount is 5 to 15 wt% in combination with VC of .mu.m or less.