JPH038268B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a wire dot head that performs printing by driving a dot wire using the spring force of a leaf spring.

[Prior art]

Conventionally, the printing element 1 in this type of wire dot head is made of austenitic stainless steel, with its base end fixed to a yoke 2 and a dot wire 3 fixed to its free end, as shown in FIGS. 1 to 3. A reinforcing rib 5 is laser welded to the leaf spring 4 made of (SUS301-H) at the laser point △ on the side where the dot wire 3 extends, and an armature 6 made of low carbon steel is attached to the opposite side at the laser point ×. However, volume changes occur due to changes in the crystal structure due to melting by laser welding, which can cause microcracks to occur in the welded area, and laser heat can cause As shown in the figure, the strength of the weld is weak because the hardness of the weld and its surroundings decreases, so the fatigue life of the weld is limited by the bending moment that acts on the weld every time the dot wire 3 is driven and prints. This has the disadvantage that the length becomes extremely short, leading to breakage of the leaf spring and failure of the wire dot head.

Note that the numerical values in FIG. 4 indicate the Vickers hardness.

[Purpose of the invention]

This invention was made in order to deal with such conventional circumstances, and it is possible to create a welded part that does not generate any holes or microcracks caused by welding the leaf spring and armature, and does not reduce the hardness. The purpose of the present invention is to manufacture a wire dot head with high strength and provide a wire dot head with fewer failures.

[Solution]

In order to achieve the above object, the present invention provides a wire dot head that biases a leaf spring brazed to an armature and thereby drives a dot wire, which contains 13.50 to 15.50% by weight of Cr.
Ni6.50~7.75wt%, Si1.00~2.00wt%,
Cu0.40~1.00wt%, Mn1.00wt% or less, Ti0.20
~0.65 wt%, C0.09 wt% or less, P0.040 wt%
Hereinafter, the leaf spring is characterized in that it is made of a material in which S is 0.030% by weight or less and the remaining amount is Fe.

〔Example〕

Hereinafter, embodiments embodying the present invention will be described with reference to FIGS. 5 to 8.

FIG. 5 shows a side sectional view of the wire dot head 7, and 8 is a frame, which is composed of a rear yoke 9 in the shape of a flat circular container and a front yoke 10 in the shape of a disk. and front yoke 10
A permanent magnet 11 and a spacer member 1 are provided between the
2 is interposed.

13 is a plurality of leaf springs, for example 16,
Cr13.50~15.50wt%, Ni6.50~7.75wt%,
Si1.00~2.00wt%, Cu0.40~1.00wt%,
Mn1.00wt% or less, Ti0.20~0.65wt%, C0.09
Material with weight% or less, P0.040 weight% or less, S0.030 weight% or less, and the remaining amount is Fe, i.e., it has a martensitic structure in the solution treatment state, and Si, Cu, and Ti are effective as precipitation hardening elements. It is made of precipitation-hardened martensitic stainless steel, and protrudes radially inward from the annular substrate 14. A substrate 14, which is the base end thereof, is clamped and fixed between the spacer member 12 and the front yoke 10. A base end portion of a dot wire 16 is fixed to the free end portion 15 of each leaf spring 13 by brazing.

In addition, 2.5% Si, which is low carbon steel, is added to the intermediate portion 17 between the substrate 14 and the free end 15 of the leaf spring 13.
An armature 18 made of steel (SUYP-S2.5) is fixed, and a reinforcing rib 19 made of the same material as the leaf spring 13 is brazed to the opposite surface.

Reference numeral 20 denotes 16 electromagnet devices corresponding to each of the leaf springs 13, and these electromagnet devices 20 are provided with a core 21 that projects from the rear yoke 9 and whose tip faces the surface 18a of the armature 18 on the leaf spring 13.
and an electromagnetic winding 22 wound around the core 21. In addition, 23 is the front yoke 10
This is a guide frame attached to the guide frame, and 16 insertion holes are formed in the center thereof, through which the tips of the dot wires 16 are inserted.

Next, regarding the above leaf spring 13 (product of the present invention, aged for 1 hour at 480 degrees Celsius) and leaf springs made of other materials (SUS631, SUS301, aging treatment conditions are shown in the figure), Its hardness characteristics, tensile characteristics, spring limit value, Young's modulus, and fatigue characteristics are shown in FIGS. 10 to 14. As described above, the leaf spring 13 has very excellent characteristics at a cold rolling rate of 30%, for example. Furthermore, it has properties equivalent to SUS631 in terms of fatigue properties, which are very important for leaf springs used in wire dot heads. Furthermore, in other properties, properties superior to those of other materials can be obtained. This seems to be because fine intermetallic compounds are precipitated and hardened by aging treatment in the martensite phase generated after solution treatment.

The operation of the wire dot head constructed in this way will be explained.

In this wire dot head, the permanent magnet 11 → spacer member 12 → substrate 14 → front yoke 10 → leaf spring 13 → armature 18 → core 21 → rear yoke 9 magnet Since the armature 18 is attracted to the core 21 by the magnetic force of the permanent magnet 11, the leaf spring 13 is biased in the direction of the arrow shown in FIG. 5 and stores bias energy. When the electromagnetic winding 22 of the electromagnet device 20 is energized, the electromagnet device 20 generates a magnetic force that cancels the magnetic force of the permanent magnet 11.
The free end 15 of the leaf spring 13 corresponding to this electromagnet device 20 moves in the direction opposite to the arrow in FIG. Printing paper (not shown)
Printing is performed on the Next, the electromagnet device 2
When the electromagnetic winding 22 of No. 0 is de-energized, the free end 15 of the leaf spring 13 is again attracted to the core 21 by the magnetic force of the permanent magnet 11, and this operation is repeated. Desired printing can be performed by this.

When the leaf spring 13 is bent as shown in FIGS. 5 and 6 in this manner, a large bending moment is applied to the welded portion of the leaf spring 13 to which the armature 18 is welded. If the brazing joint is performed using the welded part, there will be no occurrence of minute cracks due to melting of the welded part, and the hardness will not decrease, so the leaf spring 13 is less likely to break at the welded part.

Next, welding between the leaf spring 13 and the armature 18 will be explained.

First, considering magnetic properties, etc., it is a low carbon steel.
On the surface of the armature 18 made of 2.5% Si steel (SUYP-S2.5), a copper film with excellent conductivity is pre-plated as a brazing material to an appropriate thickness, and then as a precipitation hardening element, A plated armature 18 is placed on a plate spring 13 made of precipitation hardening martensitic stainless steel that effectively utilizes Si, Cu, and Ti. Then, when the leaf spring 13 and the armature 18 are heat-treated in a high-temperature furnace at a temperature that can melt copper (about 1130° C.), the copper film plated on the armature 18 is melted. Copper is filled between the leaf spring 13 and the armature 18 by capillary action, and as the copper is cooled, the leaf spring 13 and the armature 18 are copper-brazed. At this time, as shown in Figures 7 and 8, no cracks were generated in the welded part, and the hardness of the welded part did not decrease (approximately Hv450 including the welded part). Even if concentrated stress is applied to the welded part due to the printing operation, the leaf spring 13 is less likely to break at the welded part,
The durability of the wire dot head is more than doubled compared to conventional leaf spring materials and welding methods.

After this copper brazing work, hardening work is performed by aging treatment. Then, during the copper brazing, the leaf spring 13
Although the hardness of the tip is impaired, sufficient hardness can be obtained since the hardening operation is performed afterwards.
The curing temperature of the aging treatment of the leaf spring 13 is Celsius.
It is relatively low at 480 degrees Celsius, so it only needs to be heated to about 480 degrees Celsius during aging treatment, so there is no remelting of the brazing filler metal (copper), and there is no adverse effect on the copper brazed parts. .

Although copper was used as the brazing material in the above embodiments, other brazing materials such as nickel may be used without any problem.

By the way, in another experiment, a plate spring was formed using the precipitation hardening martensitic stainless steel of the present invention, and the plate spring and armature were laser welded. Although the fine cracks were somewhat reduced compared to the conventional leaf spring material (SUS301-H), they were not completely eliminated (see Fig. 9), so the durability of the wire dot head was not significantly improved.

〔Effect of the invention〕

As described in detail above, the present invention provides a wire dot head that biases a leaf spring brazed to an armature and thereby drives a dot wire, with Cr13.50 to 15.50% by weight and Ni6.50 to
7.75% by weight, Si 1.00-2.00% by weight, Cu 0.40-1.00% by weight, Mn 1.00% by weight or less, Ti 0.20-0.65% by weight,
Since the leaf spring was made of a material with C0.09% by weight or less, P0.040% by weight or less, S0.030% by weight or less, and the remaining amount of Fe, the welded part of the leaf spring and armature is not melted. This eliminates the occurrence of minute cracks and decreases in hardness, increasing the fatigue life of the welded portion between the leaf spring and the armature, and reducing the number of failures of the wire dot head. Furthermore, since we adopted brazing as the welding method,
The welded area between the leaf spring and the armature becomes larger, and the absolute strength of the entire welded part can be increased, so the effects are extremely large.

[Brief explanation of the drawing]

Figures 1 to 3 show the laser welding points of a conventional wire dot head, and Figure 4 shows the plate spring after laser welding the conventional plate spring and armature and measuring the hardness near the laser point. A photograph showing the surface, FIG. 5 is a sectional view showing the outline of the charge type wire dot head according to the present invention, FIG. 6 is an enlarged sectional view of the main part of FIG. 5, and FIG. Fig. 8 is an enlarged electron micrograph of Fig. 7, Fig. 9 is an electron micrograph showing the state in which the leaf spring and armature are laser welded, and Fig. 10 is the hardness of the leaf spring. Figure 11 is a diagram showing the tensile characteristics of the leaf spring, Figure 12 is a diagram showing the spring limit value of the leaf spring, Figure 13 is a diagram showing the Young's modulus of the leaf spring, and Figure 14 is a diagram showing the leaf spring's spring modulus. FIG. 3 is a diagram showing fatigue characteristics of a spring. 7 is a wire dot head, 13 is a leaf spring, 14
16 is a dot wire, 18 is an armature, and 19 is a reinforcing rib.

Claims (1)

[Claims] 1. A wire dot head that biases a leaf spring brazed to the armature and thereby drives a dot wire, comprising: 13.50 to 15.50% by weight of Cr, 6.50 to 7.75% by weight of Ni,
Si1.00~2.00wt%, Cu0.40~1.00wt%,
Mn 1.00% by weight or less, Ti 0.20-0.65% by weight, C 0.09
A wire dot head characterized in that the leaf spring is made of a material in which the balance is Fe, P0.040 wt% or less, S0.030 wt% or less, and the remaining amount is Fe.