JPH0476310B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to improving the abrasion resistance, corrosion resistance, and chipping resistance of dot wires used in dot printers. [Prior Art] Conventionally, high speed steel and tungsten carbide (WC)-based cemented carbide have been mainly used as dot wires. Since high speed steel has inferior corrosion resistance and wear resistance compared to WC-based cemented carbide, there is a shift towards WC-based cemented carbide. On the other hand, although WC-based cemented carbide has better corrosion and abrasion resistance than high-speed steel, depending on the type of ink, corrosion resistance may become a problem. In addition, it has a high specific gravity of 13 to 14 g/cm ³ and a large inertial force, making it unable to keep up with higher printing speeds. [Problems to be Solved by the Invention] The present invention further improves the wear resistance and corrosion resistance of the above-mentioned WC-based cemented carbide dot wire, reduces the weight in order to keep up with higher speeds, and increases the service life. The purpose is to measure the [Means and effects for solving the problem] Therefore, the present applicant has previously applied for Japanese Patent Application Laid-Open No. 61-
Based on the content described in No. 143550, we conducted repeated studies to improve not only the toughness of the cermet dot wire but also its fatigue strength. As a result, we found that fatigue strength is affected not only by the toughness of the alloy but also by the surface texture of the dot wire. I found some insight. As a result, coating the surface with soft metal suppressed the occurrence of fatigue cracks on the surface and improved fatigue strength. Furthermore, in order to further improve the corrosion resistance, we investigated several dozen additive elements and found that rhenium and chromium improve the corrosion resistance of cermets. Furthermore, we investigated the particle size of the double carbide in the dispersed phase and found that fine particles of 1μ or less can further improve toughness. This is because the finer particles have a larger surface area, and when the same amount of surrounding tissue is formed, the thickness of the surrounding tissue decreases, and the rate of skeleton formation described above decreases. This is Figure 1A
As shown in the figure, the center of the Ti(CN) particle contains Ti and a core containing a large amount of nitrogen (CORE), and the periphery contains Mo, W,
A so-called peripheral tissue containing a large amount of Ta, etc. is formed. This surrounding tissue is composed of Ti(CN) due to its composition.
Ti(CN) has better wettability to the binder phase than Ti(CN).
This improves the toughness of the base, but on the other hand, it tends to bring the carbonitride particles into contact with each other, as shown in FIG. 1B. This contact between carbonitride particles (hereinafter referred to as skeleton) reduces crack propagation resistance and is one of the reasons why toughness is not improved. Next, we will discuss the numerical values and the reasons for the limitations. If the amount of double carbonitride is less than 50%, the desired wear resistance cannot be obtained, and if it exceeds 90%, the toughness of the alloy will be impaired, so the amount is set at 50 to 90%. Substitution amount of 4a, 5a, 6a genera excluding Ti is 10%
If the content is less than 70%, the effect of improving the wettability of Ti(CN) and the binder phase is small, and if the content exceeds 70%, Ti(CN)
10-70% due to deterioration of original wear resistance and corrosion resistance
And so. If the binder phase is less than 10%, the fracture resistance of the alloy will be poor;
Moreover, if the content exceeds 50%, wear resistance will be impaired, so the content was set at 10 to 50%. If the thickness of the surface coating is less than 0.5μ, the effect of improving fatigue strength will be small, and if it exceeds 50μ, the wear resistance will deteriorate, so it was set to 0.5 to 50μ. If rhenium is contained in an amount less than 0.5%, no improvement in corrosion resistance will be observed, and if it is contained in an amount exceeding 5%, the sinterability of the alloy will be deteriorated, so the content was set at 0.5 to 5%. If the content of chromium is less than 0.5%, no improvement in corrosion resistance will be observed, and if it exceeds 15%, the toughness of the alloy will deteriorate, so the content was set at 0.5 to 15%. For the reason mentioned above, the particle size is
If it is less than 1μ, the toughness of the alloy will further improve.
It was set to 1μ or less. [Example] Next, the cermet dot wire of the present invention will be explained based on an example while comparing it with a comparative dot wire. The raw material powder was mixed and pulverized in a ball mill for 96 hours to have the composition shown in Table 1 with C/N=3, and after adding a plasticizer, it was kneaded and extruded into a diameter of 0.5 mm. Next, it was degreased and sintered at 1350°C for 30 minutes to create a wire. Next, this wire was centerless ground to a diameter of 0.3 mm, and then coated with 3μ of Ti and Al by vacuum evaporation to create a dot wire. The physical properties of this alloy are also listed in Table 1. Transverse rupture strength is the result of a three-point bending test with a span distance of 10 mm. Next, cantilever with amplitude 4mm, 50Hz, stress 130Kg/mm ²
The fatigue test was carried out 10 times, and the average number of fatigue failures was calculated, which is shown in Table 2. Further, a mounting test was conducted and the amount of wear at the tip was measured according to FIG. 2, and the results are shown in Table 3.

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【table】

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〔Effect of the invention〕

From the above results, the cermet dot wire of the present invention has reduced weight and improved fatigue strength, so that a stable life can be obtained. The cermet of the present invention also has a density of about 6.0 to 9.0 g/cm ³ , which is about half that of WC-based cemented carbide, and can sufficiently follow future increases in speed.

[Brief explanation of drawings]

In Figure 1A, Mo, W,
An explanatory diagram of the so-called peripheral tissues containing large amounts of Ta, etc.
FIG. 1B shows an explanatory diagram when carbonitride particles contact each other and form a skeleton. Figure 2 shows the measurement positions for the amount of wear.

Claims (1)

[Claims] 1. As a dispersed phase-forming component, a part of Ti in titanium carbonitride having a C/N ratio of 1 or more is contained in a range of 10 to 70% by weight from 4a, 5a and 5a of the periodic table excluding Ti. A binder phase consisting of 50 to 90% by weight of a double carbonitride substituted with one or more of group 6a metals, and the remaining 50 to 10% by weight of one or more of iron group metals and unavoidable impurities. A surface-coated cermet dot wire characterized in that the surface is further coated with one or more metals such as Al, Cu, and Ti to a thickness of 0.5 to 50μ. 2. In the alloy according to claim 1,
0.5-5% rhenium or 0.5-5% of the total bonded phase
A surface-coated cermet dot wire characterized by containing 15% chromium. 3. A surface-coated cermet dot wire characterized in that the average particle size of the dispersed phase of the double carbonitride in the alloy according to claim 1 is 1 μm or less.