JPH057185B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing wire used in a dot impact type printing head.

[Prior Art] Conventionally, some printing wires used in dot impact printing heads have a wire pin fixed to one end of the wire.

Printing wires and wire pins are required to have excellent wear resistance, toughness, and heat resistance. For this reason, traditionally materials such as cemented carbide, high-speed tool steel, and tungsten have been used for wires, and wire pins have been made of high-carbon steel that has been hardened and tempered, or that has been surface hardened by nitriding. Materials such as low carbon steel are used.

The wire and the wire pin are connected by brazing, thermocompression bonding, cold compression bonding, or the like.

[Problems to be Solved by the Invention] However, since joining by brazing is extremely complicated and time-consuming, there is a problem in that manufacturing costs are high.

In addition, when using high carbon steel that has been hardened and tempered for wire pins, heat treatment must be applied at the same time as heating during bonding in order to prevent phase transformation due to heating during brazing or thermocompression bonding. However, there is a problem in that it becomes very difficult to control the processing temperature. Furthermore, when a wire pin subjected to surface hardening treatment is used, there is a drawback that cracks are likely to occur during cold press bonding.

Therefore, the purpose of this invention is to reduce manufacturing costs by bonding wires and wire pins with sufficient strength without complicated operations such as brazing or strict temperature control during heat treatment. .

[Means for Solving the Problems] A feature of the present invention is that a wire formed of a steel material and a wire pin are temporarily connected at a joint portion, and a diffusion method is performed to precipitate metal carbide on the surfaces of the wire and the wire pin. The process is performed to precipitate a metal carbide layer in the minute gaps created in the bonded portion.

[Operation] When a diffusion treatment is performed to precipitate metal carbide on the surface of the wire and wire pin in a temporarily bonded state, metal ions will also invade into the micro gap that is created at the bond between the wire and wire pin. As a result, metal carbides are formed within minute gaps. The metal carbide formed within this minute gap serves as a bonding agent between the wire and the wire pin, improving the bonding strength between them.

In addition, if the wire and wire pin are carburized to increase the carbon content before the above-mentioned diffusion treatment, even if carbon is consumed when metal carbide is formed, the inside of the wire and wire pin will remain intact. It is possible to contain carbon in an amount that allows the quenching and tempering treatment to fully exhibit its effects.

Furthermore, when chromium carbide is formed as a metal carbide, chromium carbide has a higher affinity with steel materials than other metal carbides, so even if quenching and tempering is performed after forming chromium carbide, the wire and It does not peel off from the surface of the wire pin, and the desired bonding strength and wear resistance can be obtained.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

First, the wire 1 and the wire pin 2 are temporarily connected as shown in FIG. In this embodiment, hard steel wire or piano wire was used as the material for the wire 1, and low carbon free-cutting steel such as SUM material with excellent workability was used as the material for the wire pin 2. After fitting the wire 1 into the wire insertion hole 2a of the wire pin 2,
They were joined by cold crimping (caulking). From FIG. 1, in the joint 3 between the wire 1 and the wire pin 2,
It is observed that a minute gap 4 is formed.

Then, immerse the printing wire in powdered carbon,
Solid carburization, which involves heat treatment at 1000°C for 2 hours, reduces the amount of carbon contained in wire 1 and wire pin 2.
It was increased to about 1.2-1.5 weight percent.

After that, the printing wire 3 was buried in a mixture of powdered chromium and powdered ammonium chloride as a catalyst in a ratio of approximately 10:1, and heated at 1000°C.
Solid diffusion treatment was performed by applying heat treatment for 0.75 hours. As a result, as shown in FIG.
A chromium carbide layer 5 is also precipitated within a minute gap 4 (shown in the first diagram) formed at the joint 3 with the chromium carbide layer. Joint part 3
The chromium carbide layer 5 is deposited through the openings at both ends of the wire insertion hole 2a in the wire pin 2. More chromium carbide layer is deposited. Furthermore, as a result of X-ray diffraction, the chromium carbide layer 5 contains Cr ₂₃ C 8 , Cr 23 C ₈ ,
It was confirmed that Cr ₇ C ₃ and Cr ₃ C ₂ compositions were precipitated in layers. The surface hardness was 1500Hv to 2000Hv in terms of microvits hardness.

Thereafter, a quenching treatment was performed by heating to 850°C and oil cooling, followed by a tempering treatment at 400°C for 0.5 hours.

FIG. 3 shows the joint 3 after the quenching and tempering treatment (final treatment), and shows that even after the quenching and tempering treatment, the wire 1 and the wire pin 2 are strong due to the chromium carbide layer 5. It can be confirmed that the .

FIG. 4 shows a graph comparing the maximum pull-out strength when the wire 1 is pulled out from the wire pin 2 between a printing wire that is only temporarily joined to the wire 1 and the wire pin 2 and a printing wire that is a final processed product according to the present invention. As can be seen, the maximum pull-out strength of the printing wire according to the present invention is improved by 4 to 5 kgf compared to the printing wire that is only temporarily bonded.

Furthermore, as shown in FIG. 5, the pull-out strength-elongation curve of the printed wire according to the present invention has two modes: a first mode that shows a sharp peak, and a second mode that rises again after the first mode and shows a gentle peak. The peak of the pull-out strength in the first mode almost coincides with the maximum pull-out strength shown in FIG.

FIG. 6 shows the connecting portion between the wire 1 and the wire pin 2 at the end of the first mode in FIG. It is recognized in Fig. 6 that the chromium carbide layer 5 has been destroyed, and a comparison with Fig. 3 confirms that the improvement in the maximum pullout strength shown in Fig. 4 is due to the precipitation of the chromium carbide layer 5. can.

As shown in FIG. 7, as a result of the quenching and tempering treatment, the internal structure of the wire 1 is a uniform tempered martensitic structure similar to that obtained when ordinary high carbon steel is quenched and tempered. Its internal hardness is microbits hardness 450Hv ~
500Hv was obtained, and the desired toughness was also obtained. Further, even after the quenching and tempering treatment, the chromium carbide layer 5 formed on the surface of the wire 1 did not peel off, and the surface hardness maintained a micro-Vickers hardness of 1500 Hv to 2000 Hv.

Figure 8 shows the relationship between the number of durable dots and the amount of wear at the tip when a 10 μm chromium carbide layer is formed on a wire with a diameter of 0.3 mm. As can be seen, the wear at the corner of the tip of the printing wire progresses faster than at the center of the tip, but the center of the tip has a durability of about 250 million dots, and the printing wire has a durability of about 250 million dots. It has a durability of over 300 million dots against the practical wear limit of 100μ. It is also recognized that the printing wire according to the present invention has superior durability compared to wire made of high-speed tool steel, and is significantly superior at the level of 200 million dots or less.

Although this example shows an example in which the wire and wire pin are temporarily joined by cold crimping, this temporary joining is not limited to cold crimping. For example, methods such as press fitting may be used. It's good to wear. Further, the mixing ratio of powdered chromium and powdered ammonium chloride, each heat treatment condition, etc. can be selected as appropriate, and the steel material is not limited to low carbon steel, for example, silicon steel or high carbon steel can also be used.

Further, the metal carbide is not limited to chromium carbide, and for example, titanium carbide, vanadium carbide, niobium carbide, etc. may be precipitated.

[Effects of the Invention] As explained in detail above, according to the present invention, a hardened surface layer can be formed through a single treatment process, and at the same time, wires and wire pins can be bonded with higher bonding strength. I can do it. Therefore, the bonding strength between the wire and the wire pin is large,
It is possible to easily produce a lightweight, inexpensive printing wire with excellent abrasion resistance, and it is extremely effective industrially.

[Brief explanation of the drawing]

The drawings relate to an embodiment of the present invention, in which Fig. 1 is a micrograph showing the metallographic structure of the bonded portion showing a state in which the wire and wire pin are temporarily bonded, and Fig. 2 is a photomicrograph showing the metallographic structure of the bonded portion where a chromium carbide layer has been deposited. Figure 3 is a micrograph showing the metallographic structure of the joint after final treatment, Figure 4 is a comparison of maximum pullout strength, and Figure 5 is a comparison of pullout strength and 6 is a micrograph showing the metal structure of the bonded portion at the end of the first mode shown in FIG. 5, FIG. 7 is a micrograph showing the metal structure of the tip of the wire, and FIG. The figure is a diagram showing the relationship between the number of durable dots and the amount of wear at the tip. 1...Wire, 2...Wire pin, 3...Joining portion, 4...Minute gap, 5...Chromium carbide layer.

Claims (1)

[Scope of Claims] 1. A wire made of a steel material and a wire pin are temporarily joined at a joint part, and a diffusion treatment is performed to precipitate metal carbide on the surfaces of the wire and the wire pin, and at this time, the wire pin is temporarily joined at the joint part. A method for manufacturing a printing wire, characterized in that a metal carbide layer is precipitated at minute intervals occurring in the wire. 2 Carburizing a wire and a wire pin formed of a steel material, and with the wire and wire pin temporarily bonded at the joint, a diffusion treatment is performed to precipitate metal carbide on the surfaces of these, and at this time, the wire and wire pin are temporarily bonded at the joint. A method for manufacturing a printing wire, characterized in that a metal carbide layer is precipitated at minute intervals occurring in the wire. 3. The method for manufacturing a printing wire according to claim 1, wherein the metal carbide is chromium carbide. 4. The method for manufacturing a printing wire according to claim 2, wherein the metal carbide is chromium carbide.