JPS5813013B2 - Swivel armature electromagnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Recently, rotating armature electromagnets have been used as driving electromagnets for driving print wires of print heads for wire printers.

This type of wire printer is a so-called impact type dot printer that expresses characters, symbols, etc. in a dot matrix by appropriately selectively driving printing wires at high speed, and is widely used as an output device for electronic computers and the like.

This impact-type dot printer has an armature swingably supported on a yoke that supports an iron core wrapped with a coil, and when current is supplied to the coil, the connector swings, and the connector is connected to the tip of the armature. It drives the printed printing wire.

When the electromagnet configured in this manner is driven at high speed, the engagement portion between the armature and the yoke is subject to severe friction, resulting in significant wear at the engagement portion between the two.

Furthermore, the armature and yoke are generally made of a material with high magnetic permeability, such as electromagnetic soft iron, which has a low carbon content and therefore has low wear resistance, which tends to further aggravate the wear. .

Therefore, in the past, the reduction in magnetic permeability of the armature and yoke was overlooked, and carburizing and quenching was performed to improve the wear resistance of the engaging portions of the two.

In order to minimize the decrease in magnetic permeability, this carburizing and quenching is performed only on the engaging portions of the two, so that the work before and after the carburizing and quenching, such as the copper plating work and the work to remove the copper plating, is performed. This increased the work involved and made the manufacturing cost of the electromagnet high.

Moreover, the hardening process distorts the armature and yoke, reducing the manufacturing accuracy of the armature and yoke, and the wear resistance described above is not sufficient.

The present invention provides a rotating armature type electromagnet that takes into account the above-mentioned matters, and below, an embodiment of the rotating armature type electromagnet of the present invention implemented in a print head for a wire printer will be described in detail with reference to the drawings. explain.

FIG. 1 shows a print head 1 for a wire printer using a rotating armature type electromagnet according to the present invention.
Seven printing elements 4 are fixed (only one is shown),
The printing wire 5 is connected to the printing end 5 by the printing wire guide section 6.
A is guided so that they are gathered in a vertical line.

In the rotating armature electromagnet 3 used in the printing element 4 of this print head 1, an iron core 8 around which a winding 7 is wound
The front end portion 8a of is fixed to a substantially U-shaped yoke 9 formed to surround the winding 7.

10 is an armature, and recesses 10a are provided on both sides of the base end thereof.
10a is provided, and an operating portion 10b formed narrowly is provided at the tip.

The iron core 8 and armature 10 are made of a material with high magnetic permeability, such as electromagnetic soft iron, and the yoke 9 is made of low silicon electromagnetic soft iron, which has a higher magnetic permeability than electromagnetic soft iron.

Recesses 10a, 10 provided at the base end of this armature 10
a is a convex portion 9a formed at the upper end of the rear portion of the yoke 9;
, 9a, and the armature 10
is supported on the yoke 9.

As a result, the armature 10 is supported so as to be able to swing around the fitting point between the recess 10a and the projection 9a, while restricting movement in the horizontal direction.

Reference numeral 11 denotes an auxiliary frame made of synthetic resin, which is attached to the yoke 9 by fitting a dovetail groove 13 provided on the auxiliary frame 11 into a dovetail-shaped protrusion 12 protruding from the yoke 9. There is.

A through hole 14 is provided at one end of the auxiliary frame 11 and extends vertically in FIG.
b penetrates swingably.

Reference numeral 15 denotes a support portion which projects downward from the auxiliary frame 11 in FIG. 1, and supports the printing wire 5 in a slidable manner.

Reference numeral 16 denotes an abutment fitted to the base end of the printing wire 5, and a compression spring 17 is disposed between the abutment 16 and the support portion 15.

This compression spring 17 urges the printing wire 5 to the left in FIG.
b is also biased to the left in FIG.

As shown in FIG. 3, the portion where the actuating portion 10b of the armature 10 engages with the abutting element 16 is provided with glass fibers 6, 6.
- Nylon is inserted into the actuating part 10b and the contact element 1.
This reduces the impact between the two and minimizes the wear between them.

Reference numeral 18 denotes a coil stretched between the convex portions 9a, 9a of the yoke 9, and as shown in FIG. It is stretched.

Moreover, this coil spring 18 is connected to the recess 10 of the armature 10.
It is stretched so as to press downward in FIG. 2 over the center of rotation of the armature 10 formed by the convex portion 9a of the yoke 9.

FIG. 4 is an enlarged sectional view of the center of rotation between the yoke 9 and the armature 10.

As shown in the figure, the yoke 9 is coated with electroless nickel plating (hardness approximately Hv55) with a thickness of approximately 10 microns on its peripheral surface.
0), and then heat treated at 400°C for 1 hour (to achieve a hardness of approximately Hv800), and has wear resistance higher than that of hard chromium.

On the other hand, the armature 10 is coated with hard chromium electroplating (having a hardness of about Hv900) to a thickness of about 20 microns.

Therefore, the engaging parts 9b and 10c between the yoke 9 and the armature 10 are frictionally engaged with the heat-treated electroless nickel plated part and the hard chromium plated part, so that the armature 10 can perform high-speed oscillating motion for a long time. Even if this is done, there will be very little wear between the two.

Further, since the influence of electroless nickel plating on the magnetic permeability of the yoke 9 and the influence of hard chromium plating on the magnetic permeability of the armature 10 are extremely small, the entirety of the yoke 9 and the armature 10 is coated with electroless nickel plating. and hard chrome plating, making the plating process easy.

When a driving DC current is supplied to the winding 7 of the electromagnet 3, the armature 10 is moved against the compression spring 17 to the position shown by the two-dot chain line in FIG.

As a result, the printing wire 5 is moved to the right in FIG. 1, and the printing end 5a prints on the platen 19 via the ink ribbon 20 and printing paper 21, thereby printing dots on the printing paper 21.

The printing wire 5 that has been stamped on the platen 19 immediately returns to the position shown in FIG. 1 together with the armature 10 by the urging force of the compression spring 17.

Although the embodiments have been described using electroless nickel plating, similar effects can be obtained by using nickel-phosphorous electroplating.

As detailed above, the present invention improves wear resistance by applying electroless nickel plating or nickel-phosphorus electroplating to the armature 10 of the yoke 9 made of a material with high magnetic permeability and low wear resistance. This reduces many work steps compared to conventional carburizing and quenching, enables manufacturing at low cost, and further improves wear resistance.

Further, as described in detail in the embodiments, by applying electroless nickel plating to the yoke and applying hard chromium plating to the armature, wear between the two can be significantly reduced.

Further, by heat-treating the yoke after electroless nickel plating, the wear resistance of the yoke can be further improved.

[Brief explanation of drawings]

FIG. 1 is a print head for a wire printer embodying the present invention, FIG. 2 is a partially enlarged perspective view, and FIGS. 3 and 4 are partially enlarged sectional views of a printing element 4. In the figure, 1 is a print head, 3 is an electromagnet, 5 is a printing wire, 8 is an iron core, 9 is a yoke, and 10 is an armature.

Claims (1)

[Claims] 1. In a rotating armature electromagnet, either the yoke that supports the coil core or the engaging portion of the armature swingably supported by the yoke is coated with electroless nickel plating or nickel. - A rotating armature electromagnet characterized by being electroplated with phosphorus and hard chromium electroplating on the other side. 2. The rotating armature electromagnet according to claim 1, wherein the yoke is electroless nickel plated, and the armature is electroplated with hard chromium. 3 After electroless nickel plating is applied to the yoke,
3. The rotating armature electromagnet according to claim 2, which is heat-treated.