JPS6176676A - Pin for dot printer - Google Patents

Abstract

PURPOSE:To obtain the titled pin which is soft, superior in wear resistance and easy for machining, by covering TiC or TiN on surface of sintered body in which specified ratios of carbides, etc. of metal in IVa, Va, VIa groups are added to tetragonal crystal ZrO2. CONSTITUTION:Mixture composed of 10-25vol% at least one kind among carbide, nitride, boride of metal in IVa, Va, VIa groups and solid soln. thereof, and the balance tetragonal crystal ZrO2 powder is formed, and sintered in nonoxidizing atmosphere. Fine powder contg. 2-5mol% Y2O3 obtd. by coprecipitation method, etc. is used for ZrO2. Next, said sintered body is further hot pressed hydrostatically to high strength material, it is finished to a necessary size by discharge machining, then covering layer of TiO or TiN having <10mu thickness is formed at least one part of the surface by known CVD method, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dot printer pin for an impact dot printer or an impact line printer such as a computer output terminal.

[Conventional technology]

Tungsten wire has traditionally been used as a printing pin material for dot printers. In response to the demand for faster printing speed and clearer printing, we developed a highly abrasion-resistant material.
- The use of cod cemented carbide pin material is increasing. However, since the cemented carbide pin is heavy, it is difficult to further improve printing speed and print clarity. Cermet pin materials have been developed to make the pins lighter, but they have problems with wear resistance and have not been put to practical use.

[Problem that the invention seeks to solve]

The present invention aims to provide a pin that is light, has excellent wear resistance, can be subjected to electric discharge machining as a pin for a dot printer, and can be easily attached to a printer.

[Means for solving problems]

In order to achieve the above objects, the present invention provides IV&XVa
% 10 to 25 volume % of at least one of group VIa metal carbides, nitrides, borides, and solid solutions thereof, and the remainder is tetragonal zirconia, and at least part of the surface thereof A dot printer pin is provided with a TiC or TiN coating layer.

The zirconia used in the pin of the present invention contains YO obtained by coprecipitation method, hydrolysis method, or alkoxide method.
It is desirable to use a fine powder containing 5 mol. Y
O is effective in increasing the proportion of the tetragonal zirconia phase in the sintered body.

The pin of the present invention has the above-mentioned zirconia powder, ■a1Va1V
Powders of at least one of Group Ia metal carbides, nitrides, borides, and solid solutions thereof are mixed, shaped, and sintered in a non-oxidizing atmosphere. If this sintered body is further subjected to hot isostatic pressing, a material with even higher strength can be obtained. Finish this material to the required dimensions by electric discharge machining, and
ic! %l'iN coating layer by known CVD method, PVD
form by law.

[Effect]

The tetragonal zirconia sintered body has a bending strength of 180 kg/tonne and is excellent in rigidity and wear resistance.

However, it is not conductive at room temperature and cannot be subjected to electrical discharge machining, which is the final machining of pins. The conductivity and electrical constant of the sintered body that can be subjected to electrical discharge machining are 1×10 Ω or more. In order to provide this conductivity, at least one of the group metal carbides, nitrides, borides, and solid solutions thereof is added. If it is less than 25% by volume, the above-mentioned electrical conductivity will not be achieved, and if it exceeds 25% by volume, the strength will decrease, so the amount of these additions should be 10 to 25% by volume.

The reason why the Ties TiN coating layer is provided on part or all of the surface is that it has good wettability with the brazing material, has good reactivity with the component that imparts conductivity, and has good adhesion to the base material. excellent,
This is so that it can be easily attached to a printer by brazing, similar to conventional tungsten materials and cemented carbide materials. It is sufficient that the thickness of this coating layer is several μm, and preferably less than 10 μm.

〔Example〕

Example 1 Tetragonal ZrO powder containing 3 mol% of YO produced by coprecipitation method was mixed with 20% by volume of TiC powder, extruded into a round bar shape by extrusion method, and sintered at 1500C for 2 hours in vacuum. death,
Furthermore, at 1500 C in argon gas at 2000 atm.
Hydrostatic pressing for 0 minutes and electric discharge machining to create a diameter of 0.2-
Pins for dot printers with a diameter of 1 mm were prepared, various coating layers were formed as shown in Table 1, and the pins were subjected to a life test. The results are shown in Table 1. OA3, Φ, 8.9.10.11 are comparative examples, and OA1.2.5 to 7 are examples of the present invention.

As shown in Table 1, the pin of the present invention was extremely durable and could be easily attached to the printer yoke by brazing.

Those without a coating layer require a complicated structure for attachment to the printer yoke, and are mechanically expensive.

Table 1 *Comparative example Example 2 Pins with the composition shown in Table 2 were made in the same manner as in Example 1, and CVD
A TiC coating layer with a thickness of 5 μm was formed on each by a method, and the coating layer was brazed to the printer yoke and subjected to a life test. The results are also shown in Table 2.

In either case, the brazing did not cause the parts to come off, and a lightweight pin with durability of 1g2 was obtained.

Table 2 ×... Comparison example (7 doors, tetragonal (b)... monoclinic (0
)...Cubic crystal [Effects of the Invention] According to the present invention, it is possible to provide a pin material for a dot printer that is light, has excellent wear resistance, and is easy to process.

Claims (2)

[Claims] (1) At least one of carbides, nitrides, borides, and solid solutions of group IVa, Va, and VIa metals from 10 to
1. A pin for a dot printer, comprising a sintered body having a composition of 25% by volume and the remainder being tetragonal zirconia, and having a coating layer of TiC or TiN on at least a part of the surface. (2) The dot printer pin according to claim (1), wherein the TiC or TiN coating layer has a thickness of less than 10 μm.