JPH05169682A - Impact dot head - Google Patents

Abstract

PURPOSE:To obtain an impact dot head superior in long-period reliability. CONSTITUTION:A printing wire 14 made of a high speed steel containing 5-12wt.% Cr is bonded by brazing to an armature 6 provided with a thin plate part having a thickness not more than the diameter of the printing wire 14. Therefore, the printing wire 14 can be less deteriorated in hardness at the time of brazing, thus never being deteriorated in fatigue strength. In this manner, an impact dot head superior in long-period reliability is made available.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact dot head for an impact dot printer.

[0002]

2. Description of the Related Art High-speed steel, which has excellent cost performance, has been widely used as a material for printing wires of impact dot heads. Among them, Japanese Patent Laid-Open No. Hei 3
As disclosed in No. 121-855, 5 to 5% of Cr
The high-speed steel containing 12 wt% (hereinafter referred to as high-Cr high-speed steel) is particularly excellent in wear resistance and corrosion resistance, and thus has been widely used in recent years. The fixing method by brazing is generally used for fixing the print wire and the armature, and the same is true when high Cr high speed steel is used. At this time, the shape of the armature when brazing is such that the armature 506 is tapered and the thickness is larger than the diameter of the printing wire 514 as disclosed in Japanese Utility Model Laid-Open No. 61-181729 shown in FIG. , An armature with a straight shape but thicker than the diameter of the printing wire was used.

[0003]

However, since the high Cr high speed steel has a larger amount of Cr than the conventional high speed steel, the quenching hardness does not increase and the Vickers hardness is limited to about 850. When the printing wire 514 and the armature 506 are fixed to each other by brazing, a tempering action works, so that the hardness of the fixing portion of the printing wire 514 to the armature 506 deteriorates. At this time, it is known that if the hardness of the print wire 514 becomes 800 or less, the fatigue performance of the print wire 514 deteriorates, and if the print wire 514 is repeatedly printed, the print wire 514 is broken at the fixing portion with the armature 506. It was
Therefore, the printing wire 514 made of high Cr high speed steel is
It was necessary to pay particular attention to deterioration of hardness when brazing.
However, since the print wire 514 and the armature 506 are both heated when brazing, if the armature 506 has a thick shape, the heat capacity of the armature 506 becomes large, and a lot of energy must be input when brazing. Increased input energy, armature 50
When the heat capacity of 6 is large, the cooling rate of the printing wire 514 when brazing is low, and the high temperature state continues for a long time. As a result, the printing wire 5 made of high Cr high speed steel
When 14 is used, the hardness of the fixing portion of the print wire 514 to the armature 506 may be deteriorated to 800 or less in Vickers hardness, and in that case, the print wire 514 is broken due to repeated stress associated with printing. , Has been a cause of lowering the long-term reliability of the impact dot head.

The present invention has been made to solve the above-mentioned problems, and impact dots excellent in long-term reliability can be obtained by suppressing deterioration of hardness of a printing wire formed of high-Cr high-speed steel during brazing. The purpose is to provide a head.

[0005]

The present invention has a Cr content of 5 to 5.
A printing wire made of high-speed steel of 12 wt% is engaged and fixed to the tip of the thin plate part of the armature, an electromagnet is arranged facing the suction part of the armature, and the printing wire is driven by rotating the armature by the electromagnet. In an impact dot head that performs printing by applying an impact force to a printing medium, the thin plate portion of the armature has a thickness equal to or less than the diameter of the printing wire.

[0006]

1 (a) is a front view of an impact dot head showing an embodiment of the present invention, and FIG. 1 (b) is a side view thereof.
2 is a sectional view taken along line AA in FIG. FIG. 3 is a perspective view of an armature showing an embodiment of the present invention. Figure 1,
The configuration and operation of the embodiment of the present invention will be described with reference to FIGS.

A plurality of cores 2a are erected on a frame 2 made of a magnetic material, and a coil bobbin 9 is provided around the cores 2a.
A coil 7 in which a copper wire is wound around is attached to form an electromagnet. The bottom of the frame 2 is made to correspond to each core 2a.
Through holes are provided for each coil terminal 10 of the coil 7.
Is electrically connected and fixed to the substrate 17 by soldering through the through hole and the insulating plate 20. The connector 25 is soldered to the lower part of the board 17, and the coil 7 is connected to the cable 26.
Is connected to a driver circuit (not shown).
A first yoke plate 3, a second yoke plate 4, a fulcrum spacer 5, and an armature holder 21 are laminated on the upper surface of the frame 2. An armature 6 in which a thin plate portion 6b and a suction portion 6c are integrally formed of 1 wt% silicon steel is arranged at equally divided positions on the circumference at the facing portion of the core 2a. The parts are located at evenly divided positions on the circumference, and they are fixed by brazing. In this embodiment, the printing wire 14 is made of high-speed steel and has a Cr content of 10 wt%. The armature 6 is provided with a through hole 6a, the fulcrum shaft 18 is inserted into the through hole 6a, and the armature 6 is rotatably held around the fulcrum shaft 18. The fulcrum shaft 18 is sandwiched by the two fulcrum spacers 5, and is fixed by pressure contact with the first yoke plate 3 and the armature holder 21. The print wire 14 is held by a tip guide 11 attached to the nose 1, a plurality of intermediate guides 12 and a nose guide 13, and is guided by the tip of the print wire 14 in a zigzag arrangement in two vertical columns. A nose guide 13 is arranged at the center opening of the frame 2 and the nose guide 1
3 has a plurality of holes 13d, and a return spring 15 is attached to the hole 13d to press the armature 6 toward the damper 16 side made of a material having excellent vibration damping characteristics.

Next, the dimensional relationship between the armature 6 and the printing wire 14 will be described with reference to FIG. Printing wire 14
Has a diameter of 0.2 mm, and the thin plate portion 6b of the armature 6 has a thickness T of 0.15 mm. When the printing wire 14 having a diameter of 0.2 mm is brazed, the thin plate portion 6b of the armature
The relationship between the thickness T and the brazing hardness of the print wire 14 is shown in FIG. 4A. When T is 0.2 mm or less, brazing hardness of 800 or more can be secured. This is because the thickness T of the thin plate portion 6b of the armature is the print wire 1
If the diameter of the armature 4 is 0.2 mm or less, the heat capacity of the thin plate portion 6b of the armature is small, and therefore the input energy when brazing is small. As a result, the deterioration of hardness of the brazed portion of the printing wire 14 can be suppressed to a small level. Further, if the thickness T of the thin plate portion 6b of the armature becomes large, the heat capacity of the thin plate portion 6b of the armature becomes large, so that a large amount of energy is required at the time of brazing. This allows the printing wire 1
The tempering effect of No. 4 is large, and the hardness of the brazing portion of the printing wire 14 is largely deteriorated. In addition, FIG. 4B shows the result of an experiment on the thickness T of the armature when a printing wire having a diameter of 0.3 mm is brazed. At this time as well, T = 0.3 mm or less and the brazing hardness was Vickers hardness of 8
It can be seen that 00 or more can be secured.

Next, the operation will be described with reference to FIG. In the standby state, the spring force of the return spring 15 holds the armature 6 in a state of being pressed by the damper 16. When the coil 7 is pulse-energized, a magnetic attraction force is generated between the attraction portion 6c of the armature 6 and the core 2a. The armature 6 is accelerated by this magnetic attraction, and the arrow A
A rotational movement is started around the fulcrum shaft 18 in the direction. Along with that, the printing wire 14 projects and the ink ribbon 22
The print medium 23 is collided and pressed against the platen 24 via the to form dots. After the collision, the armature 6 enters the returning operation due to the repulsive force at the time of the collision and the spring force of the return spring 15, and the armature 6 is held by the damper 16 after the collision and the one printing process is completed.

By repeating this printing operation, the printing wire 1
Even if stress is repeatedly applied to the engaging portion of the armature 6 of No. 4 with the thin plate portion 6b, the hardness of the engaging portion of the printing wire 14 with the armature 6 is 800 or more in Vickers hardness, and thus the printing wire 14 Fatigue performance is sufficient,
The long-term reliability of the impact dot head can be secured.

[0011]

As described above, according to the present invention, the armature having the thin plate portion having the thickness equal to or smaller than the diameter of the printing wire is engaged with the printing wire made of the high speed steel having the Cr amount of 5 to 12 wt% by brazing. Since it is fixed, the hardness of the brazed part of the printing wire can be 800 or more in Vickers hardness, and it is possible to obtain an impact dot head with excellent long-term reliability without the fatigue breaking of the printing wire at the brazed part of the printing wire. it can.

[Brief description of drawings]

FIG. 1 is a front view and a side view of an impact dot head showing an embodiment of the present invention.

FIG. 2 is a sectional view of an impact dot head showing an embodiment of the present invention.

FIG. 3 is a perspective view of an armature showing an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing the relationship between the hardness of the brazed portion of the printing wire and the dimension of the armature thin plate portion.

FIG. 5 is a perspective view of an armature showing a conventional example.

[Explanation of symbols]

 1 Nose 2 Frame 3 First Yoke Plate 4 Second Yoke Plate 6 Armature 7 Coil 14 Printing Wire 15 Return Spring 16 Damper 17 Board 18 Support Point Shaft 20 Insulation Plate 21 Armature Holder 22 Ink Ribbon 23 Printing Medium 24 Platen

Claims (1)

[Claims] 1. A printing wire made of high-speed steel having a Cr content of 5 to 12 wt% is fixedly engaged with a tip of a thin plate portion of an armature, and an electromagnet is disposed so as to face a suction portion of the armature. In an impact dot head that performs printing by applying an impact force to a print medium by driving the print wire by rotating the armature, the thickness of the thin plate portion of the armature is set to be equal to or less than the diameter of the print wire. Impact dot head featuring.