JPH0528993B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a printing head suitable for use in a wire dot printer, and in particular, to a printing head which allows its constituent parts, a core and a yoke, to be formed easily and accurately. This invention relates to improvements in print heads and methods of manufacturing the same.

[Conventional technology]

Conventionally, this type of print head generally has a magnetic flux circuit composed of a core, a yoke, a permanent magnet, etc., and an armature supported by a leaf spring or the like within this magnetic flux circuit in a swingable manner. It has a configuration in which an excitation coil is disposed at a desired position to cancel the magnetic flux to the armature using an electric signal. The armature is always magnetically attracted by the magnetic flux from the permanent magnet, and when necessary, current is applied to the excitation coil to cancel the above-mentioned magnetic attraction force, thereby causing the armature to swing and move with the urging force of a leaf spring, etc. Printing was performed using a printing wire provided at the tip.

By the way, according to the above-mentioned conventional printing head, a required number of armatures and excitation coils are arranged in parallel in close proximity, and when printing is performed by simultaneously energizing a plurality of the excitation coils,
This has had problems such as magnetic interference occurring between individual magnetic flux circuits, changing the magnetomotive force of the permanent magnet, and deteriorating print quality. For this reason, as shown in Japanese Unexamined Patent Publication No. 60-129270, conventionally, a configuration has been adopted in which a side magnetic path is provided in parallel to a series of main magnetic flux circuits including a portion around which an armature and an excitation coil are wound. was proposed. and,
According to such a configuration, when driving the printing wire, the magnetomotive force applied to the main magnetic flux circuit by the permanent magnet increases depending on the number of driving printing wires and the pattern of the printing wire to be excited. This increase in magnetomotive force was suppressed by the presence of the side magnetic path, making it possible to obtain good printing quality without problems such as magnetic interference.

[Problem to be solved by the invention]

However, in the conventional print head having the above-mentioned configuration, the shape of each component is complicated, such as a plurality of iron core parts for winding excitation coils being integrally provided on the front end side of the core. Not only is the molding process troublesome and complicated, but it also poses a problem in terms of processing precision of each part, and the assembly work of each part is also quite troublesome, which poses a problem in terms of productivity. It also has drawbacks such as increased costs, and it is desired to take some measures that can eliminate these problems.

[Means to solve the problem]

In order to meet such demands, the print head according to the present invention has a cylindrical core in which an iron core for winding an exciting coil projects at a predetermined interval in the circumferential direction at the front end and has a flange on the outer periphery of the rear end. , is supported by a cylindrical yoke laminated and fixed to the front end of the flange via a permanent magnet, and a leaf spring installed at the front end of the yoke, and is normally connected to the iron core by a magnetic flux circuit from the permanent magnet. A cast product made of a magnetic material is provided with an armature that is magnetically attracted and has a printing needle fixed to its inner end, and the core and yoke are integrally formed by a precision casting method on a surface perpendicular to the axial direction. It is formed by dividing it by .

Further, the method for manufacturing a printing head according to the present invention includes:
A cast product made of a magnetic material, in which the core and yoke described above are integrally formed by a precision casting method using a magnetic material, with the end of the yoke on the permanent magnet side in contact with the rear end surface of the flange on the core side. is divided along a plane perpendicular to the axial direction, and these two members are inverted and combined via a permanent magnet.

[Effect]

According to the present invention, by dividing a cast product made of a magnetic material by a precision casting method along a plane perpendicular to the axial direction, the core and yoke that constitute the magnetic flux circuit can be easily and appropriately formed with high precision. By inverting these two members and combining them via permanent magnets, it is possible to easily and appropriately assemble them in the desired state.

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 shows an embodiment of a printing head according to the present invention.
It consists of an iron core part 2c for winding a plurality of excitation coils that protrudes from the front end of the base 2a at predetermined intervals in the circumferential direction and whose end face becomes the magnetic pole face 2b, and an annular flange 2d extending around the outer periphery of the rear end. A core 2, an annular permanent magnet 3 fixed to the front side of the flange 2d of the core 2, and a yoke 4 having a substantially cylindrical shape fitted concentrically to the core 2 via the permanent magnet 3. and an excitation coil 5 wound around the iron core portion 2c of the core 2.
Note that a leak portion 4a constituting a side magnetic path of the excitation coil 5 is protruded from the inner circumference of the end of the yoke 4 on the permanent magnet 3 side, which constitutes the excitation mechanism 6, and the outer circumference of the base 2a of the core 2. and are configured to face each other with a predetermined gap therebetween.

Now, according to the present invention, such an excitation mechanism 6
In this step, the core 2 and the yoke 4 are integrally formed as a cast product made of a magnetic material having the shape shown by the solid line in FIG. The structure is characterized in that it can be easily and appropriately formed by cutting and dividing it along a plane A (a plane perpendicular to the axial direction) shown by a dashed line in the figure. That is, by adopting such a configuration, not only can the above-described core 2 and yoke 4 be easily and appropriately formed, but also each part can be appropriately formed with the required shape and dimensional accuracy. It has great practical effects.

What should be noted here is that the core 2 and yoke 4, which are integrally formed by the precision casting method described above, The core 2, which is the member on the left side of the figure, is assembled by reversing the magnet in the opposite direction and then fitting and fixing it concentrically to the core 2, which is the member on the left side of the figure, with a permanent magnet 3 interposed therebetween.

In addition, when forming a semi-finished cast product made of magnetic material forming the core 2 and yoke 4 by the lost wax method, the magnetic material is
When the cylindrical part that becomes the yoke 4 is cast from the outside, a plurality of iron core parts protrude from the front end of the core 2 at predetermined intervals in the circumferential direction corresponding to the number of needles to be described later. The magnetic material can be appropriately and reliably poured into the 2c forming portion, the leak portion 4a forming portion, etc., and the molding condition thereof can be improved, which is a great advantage in terms of molding.

In addition, in the above-described configuration, the armature holder 7, the base end of the leaf spring 8, the spacer 9, and the needle holder 10 are sequentially stacked and disposed on the front end side of the yoke 4, and each is glued or screwed. The print head 1 is assembled by fixing the print head 1 with a screw or the like.

Here, as shown in FIGS. 3a and 3b, the armature holder 7 forms a line segment that serves as a fulcrum of the leaf spring 8 with a surface 7a that holds the base end of the leaf spring 8. Polygonal stepped portion 7b pressed into squares
and a radial groove 7c with an open inner end. In this armature holder 7, the fulcrum part of the leaf spring 8 is formed by a pressed polygonal stepped part 7b, which is excellent in terms of productivity. Since the stepped portion 7b is formed not in a curved line but in a straight line, the deflection characteristics of the leaf spring 8 supported by the stepped portion 7b are also excellent.

On the other hand, an armature 11 as a movable member is supported at the inner end 8a of the leaf spring 8, with respect to the fixed portion made up of the core 2, yoke 4, armature holder 7, leaf spring 8, etc. as described above. The end of the plate spring 8 on the fixed side is movably interposed in the groove 7c of the armature holder 7 with a slight gap. Further, a printing needle 12 is fixed to the inner end 11a of the armature 11 by brazing or the like. In the figure, 13 is a needle guide, and 14 is a printed circuit board for wiring to the excitation coil 5.

Here, the armature 11 is made by cutting a disc-shaped blank made of magnetic material into a semi-finished product with a cross section having the front shape of the finished product (armature 11), as shown in FIGS. 4a and 4b. Next, the semi-finished product is press punched into the side shape of the finished product (armature 11), thereby improving productivity.

According to the print head 1 having the above configuration, the magnetic flux of the permanent magnet 3 flows as a magnetic flux circuit from the yoke 4 to the armature holder 7 to the armature 11 to the core 2, so that the armature 11 is always connected to the leaf spring 8.
It is magnetically attracted to the magnetic pole face 2b of the core 2 against the spring force of. Then, a corresponding permanent magnet 3 is attached to one of the excitation mechanisms 6 provided as many as the number of needles 12.
By controlling the excitation coil 5 on and off so as to generate a magnetic flux that cancels out the magnetic flux of Ru. At this time, the magnetic flux from the excitation coil 5 does not pass through the permanent magnet 3 from the leak portion 4a of the yoke 4, but bypasses the core base 2a through a predetermined gap. Leakage to the corresponding excitation mechanism 6 is reduced, magnetic interference can be appropriately prevented, and as a result, printing quality can be significantly improved compared to the conventional one.

In addition, by adopting such a print head 1 structure, the core 2 and yoke 4 can be formed separately from a cast product made of magnetic material that is integrally formed by precision casting, and can be easily combined and used. Not only is it possible to do this, but the cylindrical part that was required due to the casting hole when adopting the lost wax method can be used as it is as the yoke 4, and the material yield is good and it is economical. There is.
Furthermore, in the structure of this embodiment, the armature holder 7
The fulcrum part of the leaf spring 8 is pressed into a polygonal shape, and the straight side is used as the fulcrum, so that the leaf spring 8 has good deflection characteristics. Furthermore, since the armature 11 can be easily formed by press punching, it has advantages such as being advantageous in terms of productivity.

Note that the present invention is not limited to the structure of the embodiment described above, and the shape, structure, etc. of each part may be modified or changed as appropriate. For example, as shown in FIG. 5, the inner diameter of the leak portion 4a of the yoke 4 may be formed to be small enough to penetrate inside the excitation coil 5, so that the print head 1 as a whole may have a small diameter. In addition, as shown in FIG. 6, the excitation coil 5, which is wound around the outer circumference of the core iron core part 2c with a small diameter and uses the stepped part as a stopper, is assembled using the leakage part 4a of the yoke 4 as a stopper. You can do it like this.

Further, in the embodiment described above, the inner surface of the leak portion 4a of the yoke 4 faces the outer circumferential surface of the cylindrical base portion 2a of the core 2 via an air gap formed by a predetermined gap. It may be configured to face the iron core portion 2c side formed at a predetermined interval. Further, although the front side of the leak part 4a of the yoke 4 is formed as a tapered surface, the present invention is not limited to this, and the rear end side of the leak part 4a may be used as a spigot part of the permanent magnet 3. be.

〔Effect of the invention〕

As explained above, according to the printing head and the manufacturing method thereof according to the present invention, the core and yoke, which are its constituent parts, are formed by dividing a cast product made of a magnetic material integrally formed by a precision casting method into two parts. form,
In addition, since these are reversed and combined and installed in series, despite the simple and inexpensive configuration,
The core and yoke, which are important in configuring the excitation mechanism, can be easily and appropriately molded with high precision, and their assembly is also easy and has excellent productivity. It has excellent effects.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the print head according to the present invention, and FIG. 2 is a cast product made of magnetic material forming the core and yoke that characterize the present invention, and a finished product made of the cast product when assembled. A schematic explanatory diagram for explaining the assembly method of the armature holder;
5 is a partially omitted front view and a cross-sectional view showing a magnetic disk forming an armature, and FIGS. 5 and 6 are cross-sectional views of essential parts showing another embodiment of the present invention. 1... Printing head, 2... Core, 2a... Cylindrical base, 2b... Magnetic surface, 2c... Iron core, 2d
...Flange, 3...Permanent magnet, 4...Yoke,
4a...Leak part, 5...Exciting coil, 6...Exciting mechanism, 7...Armatule holder, 7b...Step part, 7c...Radial groove, 8...Leaf spring, 8a...
Inner end, 10... Needle holder, 11... Armature, 11a... Inner end, 12... Needle.

[Claims]

1. A leaf spring formed by extending a plurality of spring pieces supporting the armature in a centripetal direction from the inner peripheral edge of an annular base, a head cover laminated on one side of the annular base of the leaf spring via a spring holder, and this cover. an armature holder formed on the outer periphery side of the armature holder, which is directly laminated on the other side of the annular base of the leaf spring to face the spring holder on the side, and which holds the annular base; the armature holder is perpendicular to each of the spring pieces; 1. A printing head characterized in that a polygonal stepped portion consisting of a line segment that serves as a fulcrum for a spring piece is formed by press molding on the inner peripheral edge of the support portion of the holder.

Claims (1)

A method for manufacturing a printing head, characterized in that it is assembled via a permanent magnet.