JP2979790B2 - Manufacturing method of printing hammer for dot type printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printing hammer used in a dot line printer or the like.

[0002]

2. Description of the Related Art As shown in FIG.
A print hammer 14 comprising a leaf spring 1 and an armature 2 mounted on its free end and having a dot hitting portion at its tip, a permanent magnet 5, a front yoke 3, a rear yoke 6, and a release wound around upper legs of the rear yoke 6. It is made up of an electromagnetic coil 7 and the like, and has a magnetic circuit structure for absorbing and holding the leaf spring 1 and the armature 2. The leaf spring 1 has its lower end mounted between the front yoke 3 and the spacer 4 via a fixing screw 8.

The leaf spring 1 is always attracted and held by the pole portion 9 of the rear yoke 6 via the armature 2 by the magnetic attraction force of the permanent magnet 5. When the electromagnetic coil 7 is excited, the magnetic attraction force is cancelled, and the leaf spring 1 flies by the restoring force to collide the tip of the armature 2 with a platen (not shown) via an ink ribbon and paper (not shown). As a result, dots are printed on the paper.

[0004]

Conventionally, an iron-based material was used for the leaf spring 1 and the armature 2 and both were joined by caulking. However, in order to increase the printing speed, the mounting density of the printing hammer 14 was reduced. If the height is increased, the pitch of the printing hammer 14 becomes narrow, and it is difficult to join by crimping. Also,
Sufficient mechanical strength cannot be obtained by swaging against the impact force of the printing hammer repeatedly applied many times.

[0005] For this reason, joining by brazing is conceivable. When brazing such an iron-based material, a silver-copper alloy system is suitable for the brazing material in terms of melting point and strength. It is necessary to apply Ni-based plating to both parts in advance. However, Ni-P containing 3% or more of P, which has been generally used for printer parts in the past,
When the plating is heated to the brazing temperature (630 ° C. or higher), P in the plating precipitates on the surface layer of the plating and becomes brittle. In other words, when Ni-P plating (P3% or more) is applied to both the leaf spring and the amateur, cracks are generated from the inside of the plating on the leaf spring side, which is constantly distorted during the printing operation, due to the structure of the dot printer, and it is damaged early. Resulting in.

On the other hand, Ni plating (Ni 97% or more)
The plating does not become brittle even when heated to the brazing temperature, but the wettability of the brazing material is Ni-P plating (P3 to 15%)
About 5 times larger than In this case, the surface tension is greater than the force of the capillary for the brazing material to flow into and be held in the joint, and the brazing material flows to other parts than the joint, and voids are generated without filling up the joint. In some cases, the bonding strength may decrease.

Accordingly, it is an object of the present invention to solve the above-mentioned problems and to provide a high-quality printing hammer.

[0008]

According to the present invention, in joining a print hammer consisting of a leaf spring and an amateur, Ni-P plating (Ni 97% or more) is applied to the leaf spring in advance, and Ni-P plating (P3 〜15%), and joining by brazing, thereby combining the high toughness of Ni plating and the appropriate low wettability of Ni-P plating to obtain a strong joining strength.

The main component of plating is Ni because Ni has a high solid solubility in various brazing materials and iron, and is particularly a silver-copper alloy brazing material generally used for brazing printer parts. This is because when Ni is used, Ni diffuses into both the base material iron and the copper in the brazing material, so that a high bonding strength can be obtained.
The reason why the leaf spring is made of Ni plating of high toughness (Ni 97% or more) is that the leaf spring is always subjected to distortion during the printing operation. If Ni is 97% or more, cracks do not occur from the inside of the plating even when repeatedly subjected to large strain. Ni-P plating with moderate low wettability for amateurs 3 ~
The reason for setting it to 15% is that if P is less than 3%, the flow of the brazing material may not be sufficiently suppressed, and if P is 15% or more, the brazing material does not rotate as a whole due to poor wettability of the brazing material. This is because there are times.

The plating thickness is preferably 1 to 30 μm. When the plating thickness is 1 μm or less, bonding failure due to the surface roughness of the base material is liable to occur, and when the plating thickness is 30 μm or more, the variation in the film thickness becomes large, which is preferable in a print hammer requiring high dimensional accuracy. Because there is no.

[0011]

In the printing hammer joined as described above, since the leaf spring is plated with Ni (Ni 97% or more) and the armature is plated with Ni-P (P3 to 15%), the brazing material is not joined. Is filled without causing voids, and a strong bonding strength is obtained, so that there is no possibility that cracks occur from plating during printing and damages occur.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing embodiments. FIG. 1 is a side view showing an embodiment of a print hammer made according to the present invention, and FIG. 2 is a front view of FIG.

The armature 2 is brazed to the upper end of the leaf spring 1 at a rate 50% higher than the conventional mounting density, and the pitch interval is 3 mm or less. In the manufacturing method of the present invention, first, pure Ni plating is applied to the entire surface of a leaf spring 1 made of carbon tool steel by electroplating with a plating thickness of 5 μm, and an armature 2 made of carbon tool steel is pure Ni-plated by electroless plating. P plating (P9%) is applied to the entire surface with a plating thickness of 5 μm. Next, the leaf springs 1 are inserted into the grooves of the armatures 2 and assembled into a fixing jig (not shown), and an appropriate amount of the brazing material 10 is installed at an appropriate place, one place or several places of the joint.
The brazing material 10 has JIS standard BAg-8 for vacuum brazing.
(Melting point: 779 ° C.) and heated to 820 ° C. in a vacuum furnace to melt the brazing material 10 and permeate the entire joint by capillary action. At this time, the gap at the joint, that is, the gap between the leaf spring 1 and the armature 2 is 30 to 50 μm.

According to the above-described manufacturing method, the joint between the leaf spring 1 and the amateur 2 was completely filled with the brazing material, and the fillet 11 was also formed at the joint. Since the fillet acts so that stress is not concentrated on the joint end between the leaf spring 1 and the armature 2, the joint between the leaf spring 1 and the armature 2 does not weaken at the joint end. The joint between the leaf spring 1 and the amateur 2 has a strong joint strength (tensile shear strength: 1).
5 kg / mm ² or more) having a print hammer 14 has cleared the printing 10 ⁹ times with repeatability 400 .mu.s.

FIG. 3 is a side view showing another embodiment of the printing hammer made according to the present invention. The manufacturing method is the same as that of the above-described embodiment. First, carbon tool steel is used for the leaf spring 1 and the armature 2 as in the above-described embodiment, and the leaf spring 1 is electrolytically plated with pure Ni plating (Ni 99% or more). Is applied over the entire surface with a plating thickness of 5 μm, and pure Ni—P plating (P9%) is applied over the entire surface with a plating thickness of 5 μm to the armature 2 made of carbon tool steel by electroless plating. Next, the armature is inserted into the mounting hole of the leaf spring 1 until the flange of the armature 2 comes into contact with the same, and at the rear end of the armature 2, the same brazing material as in the above embodiment is installed at one or several places. The condition, that is, heating to 820 ° C. in a vacuum furnace causes the brazing material 10 to melt and permeate the entire joint by capillary action.

As a result, the joining portion between the leaf spring 1 and the armature 2 can have a higher joining strength than the printing hammer manufactured by the caulking shown in FIG. 5 or the spot welding shown in FIG. 6, and has a repeatability of 400 μs. At 10 ⁹
It is now possible to clear the number of prints.

[0017]

According to the present invention, high-toughness Ni plating (Ni 97% or more) is applied to a leaf spring which is constantly distorted during a printing operation.
No crack is generated from inside the plating. In addition, since the armature is subjected to Ni-P plating (P3 to 15%) having an appropriate low wettability, the brazing material does not penetrate to the entire surface of the bonding portion, so that no void is generated, and the reliability of the bonding strength is improved. high. Further, since the mounting density can be increased as compared with caulking, it is possible to contribute to the improvement of the printing speed.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a print hammer made according to the present invention.

FIG. 2 is a front view of FIG.

FIG. 3 is a side view showing another embodiment of the printing hammer made according to the present invention.

FIG. 4 is a side sectional view showing an example of a printing hammer driving device.

FIG. 5 is a side view of a conventional printing hammer.

FIG. 6 is a side view of a conventional printing hammer.

[Explanation of symbols]

1 is a leaf spring, 2 is an amateur, 10 is a brazing material, and 14 is a printing hammer.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/26

Claims (3)

(57) [Claims] 1. A printing hammer having an armature joined by brazing to a free end of a leaf spring, wherein the leaf spring is plated with Ni, and the armature is N-plated.
A method for manufacturing a printing hammer for a dot-type printer, comprising: performing i-P plating; and joining by brazing. 2. The Ni contained in the Ni plating component of the leaf spring is 97%, and the P contained in the Ni—P plating of the amateur is 3 to 15%. Of manufacturing a printing hammer for a dot type printer. 3. The method according to claim 1, wherein the plating applied to the leaf spring and the armature has a thickness of 1 μm to 30 μm.