JPS61189877A - Production of joining type dot pin for dot printer - Google Patents

Abstract

PURPOSE:To increase a joining strength and to reduce a cost by welding the pin made of sintered hard alloy to the tip of a shaft material, then by performing a heat treatment with the arrangement of a meltable metal on the weld zone. CONSTITUTION:The pin 23 made of sintered hard alloy is joined with welding on the tip part 22 of bar shaped shaft body 21 which is made of high speed tool steel, using a percussion welder. The meltable metal of brazing filler metal, etc. is then coated with adhesion of the joint part of a shaft material 21 and pin 23. The heat treatment of hardening and annealing is performed at the prescribed temp. for the joining pin 23 with this state. The burr caused at the weld time of the shaft material 21 and pin 23 is formed in a smooth taper shaped external shape by the molten metal. A burr removing stage therefore becomes unnecessary and the cost can be reduced. Moreover there is no reduction in the strength due to the burr and the joining strength of the pin 23 of a dot pin 2 and shaft material 21 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a dot printer layer bonded dot pin.

[Technical background of the invention and its problems] Features required for dot pins for dot printers include wear resistance, bending strength, light weight, and low processing cost.There are no materials that satisfy all of these characteristics. Not obtained.

Therefore, a method of manufacturing a bonded dot pin by using a lightweight material with high bending strength for the shaft material and bonding a material with high wear resistance to the tip of this shaft material has been considered.

However, surface materials such as dovetails are generally difficult to join, and since the diameter of the pin is as small as 0.3 to 0.20, the joining area is extremely small and it is extremely difficult to join them together.

The joining methods include brazing and welding, but there is currently no established method for practical use.

That is, in the former case of butt brazing using silver solder, dot pins formed by the method do not have sufficient strength at the soldered portion, and the joint portion breaks during use, resulting in a short service life.

In addition, in the latter welding method, as shown in Fig. 2, if percussion welding or 7-lash welding or butt welding is performed and a pin is butt welded to the tip of the shaft material 01), Paris occurs in the weld. If there is a paris, the paris part will easily break.

Furthermore, if metal powder falls during use, it will get between the pin and the pin guide, damaging the pin and the pin guide. Therefore, the hardness of the paris that occurs in welds is high, so
The processing method for removing it also requires centerless polishing, which is expensive.

There was a drawback that the processing cost of the Paris was high and the cost of the joining pin was high, making it useless for practical use.

[Purpose of the invention]

This invention has been made in view of the above points, and aims to improve the effects of flash caused by butt joining.

The present invention provides a bonded dot pin for a dot printer that has high bonding strength and is easy to process.

[Summary of the invention]

That is, this invention involves the steps of welding a pin made of cemented carbide, which is thinner and shorter than the shaft material, to the tip of a shaft material made of high-speed tool steel, and after this step, a meltable metal is welded to the welded portion. The present invention provides a method for manufacturing a bonded dot pin for a dot printer, which comprises the step of melting the metal and adhering it to the welded portion after the metal is provided and heat treated.

[Embodiments of the invention]

Next, an embodiment of the method of the present invention will be described with reference to FIGS. 1 and 2. The same parts as in the description of the prior art will be described using the same numbers. A high-speed tool steel, such as a tungsten-based high-speed tool steel or a molybdenum-based high-speed tool steel, is used as the shaft material of the joining dot pin. As the shaft material, for example, a rod-shaped body f21) with a diameter of 0.31!11 is used. The rod-shaped body QI which is this shaft material)
A pin made of K cemented carbide is connected to the tip of the pin. For this pin (c), for example, any of the 8 types, G types, and D types, each of which has tungsten as its main component, can be used. This pin (c) is a rod-shaped piece with a diameter of, for example, 0.2 ml. As a method of joining the pin @ to the tip of the shaft material Qυ, welding is performed using a Percussion welding machine. Through this welding process, metal molten during bonding is pushed out to the surrounding area by the bonding pressure, and a crack is generated. The steps up to this point may be the same as those in the prior art.

Next, the joining pin (c) is heat treated. For example, the quenching process is carried out at a temperature of, for example, 1200°C to 1250°C.

Further, a tempering process is performed at a temperature of, for example, 520°C to 580°C.

During this heat treatment, for example, the quenching process, the shaft material I21)
A metal that can be melted at the above-mentioned quenching temperature, such as a brazing material, is attached to the joint between the pin and the pin. As this brazing material, for example, BNl-IA having a brazing temperature of 1065°C to 1205°C can be used.

A quenching process is performed with this brazing filler metal adhered to the joint. As shown in Figure 1.

It is possible to manufacture a joined dot pin (2) having a smooth taper (1) in which the "edge" of the joined portion is hidden.

Dot pins can be manufactured without any additional process.

Since it can be manufactured in this manner, a bonded dot pin with an excellent structure can be obtained without performing the expensive centerless polishing process of the conventional "paris" removal process.

Since there is no polishing process mentioned above, production efficiency is improved.

Production costs can be reduced.

Furthermore, since the Doratobi/(2) obtained by the method of the present invention is covered with a brazing material, the joint portion is reinforced and the joint strength is greatly increased.

In the above embodiment, the brazing material is melted at the same time as the hardening process to cover the joint, but the tempering process may be performed, or the brazing material coating process may be performed after the heat treatment process is completed. .

Even if the brazing filler metal protrudes from the outer diameter of the shaft material.

The removal process is relatively easy in terms of shape compared to the process of processing the root of the single-step joint.

Furthermore, an alloy having a relatively low melting point may be used, and the low melting point alloy may be melted to cover the joint portion with molten metal equivalent to one alloy acid.

〔Effect of the invention〕

As explained above, according to the method of the present invention, the joint where the dot pin is joined to the tip of the shaft material is coated with molten metal.
69. No paris removal process required. The coating has the effect of improving the strength of the joint.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining an embodiment of the method of the present invention, and FIG.
The figure is an explanatory diagram of a conventional method. 21...Shaft material 23...Bint...te
- Pa 2...Joint type dot pin agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2

Claims (3)

[Claims] (1) Welding a pin made of cemented carbide that is thinner and shorter than the shaft material to the tip of the shaft material made of high-speed tool steel;
A bonded dot pin for a dot printer, comprising the step of providing a meltable metal in the welding part after the step and heat-treating the metal to melt the metal and attach it to the welding part. Production method. (2) The method for manufacturing a bonded dot pin for a dot printer according to claim 1, wherein the pin is welded to the tip of the shaft member in a non-oxidizing atmosphere. (3) A dot printer according to claim 1, characterized in that a brazing material is provided at the joint part during a hardening process after the pin is joined to the tip of the shaft material, and the joint part is covered with the brazing material. Manufacturing method for joint type dot pins.