JPH05278234A - Printing wire assembly - Google Patents

Abstract

PURPOSE:To prevent a breakage or release of a printing wire assembly by a construction wherein an arm having a hole part in the vicinity of one end thereof, an armature securely bonded to the other end of the arm, and a leaf spring securely bonded to the armature are integrally quench and tempered, and the printing wire inserted to a slit provided in the arm from the hole part to be opened to the peripheral part thereof is brazed. CONSTITUTION:An arm 1 is press-cut so as to have a periphery 12 and a hole 11 as a slit pressing part. Holes are provided in the vicinity of the center of the arm for the reduction of a weight. The outer shape of an armature 2 is formed by press-cutting. A groove to be bonded to the arm 1 is machined in the armature 2. After a leaf spring 3 is molded, the arm 1 is inserted to the groove of the armature 2. On the other side of the armature, the leaf spring is fixed and silver soldered. An assembly of the armature 2, the arm 1, and the leaf spring 3 is quench and tempered. Furthermore, the hole 11 of the arm 1 is pressed into a slit opened to the periphery 12. A printing wire 4 is inserted to the slit and bonded using a silver solder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a print wire assembly used in a spring charge type dot printer.

As shown in FIG. 5, a print wire assembly used in a spring-charged dot printer has an arm 2 fixed to an armature 3 which is normally fixed to the end of a leaf spring 4 and further to the tip of the arm. Most often, the print wire 1 is brazed. In a spring-charged dot printer, the armature is attracted by a permanent magnet and the print wire is on standby. Then, the armature is released from the magnetic force of the permanent magnet by passing a current through the coil mounted in the vicinity thereof to cancel the magnetic force of the permanent magnet. Then, the printing wire attached to the armature via the arm is driven along the wire guide by the restoring force of the leaf spring, and the tip thereof is ejected onto the platen, paper, or ink ribbon to perform printing. The ejection force acts as a strong impact force on the print wire assembly, and this load concentrates stress on the root of the attachment portion of the print wire to the arm.

Conventionally, since one end of the print wire is joined to the flat portion of the tip of the arm by brazing, the joint area between the arm and the print wire at the joint portion is small. Since the stress of concentration causes a fatigue phenomenon at the joint, the structure is apt to cause defects such as breakage of the print wire and peeling of the joint. In order to eliminate this defect and prevent the breakage of the printing wire and the peeling of the joint, a bottomed hole is provided at the tip of the leaf spring as shown in Fig. 3, and the printing wire is inserted here and fixed by brazing. What is done is disclosed in JP-A-2-141254. Japanese Patent Laid-Open No. 2-145345 discloses a technique in which a print wire is inserted into a groove of an arm provided with a print wire mounting groove as shown in FIG. 4 and fixed by brazing.

[0004]

Among these prior arts, in the case of the structure of Japanese Patent Laid-Open No. 2-141254, the bottomed hole portion for inserting the printing wire in order to maintain the strength is inevitably wide and thick. However, when it is manufactured as an assembly, there is a problem in that the printing operation is hindered because other printing wire holding portions that are close to each other come into contact with each other, and the weight becomes heavy and the printing characteristics deteriorate. JP-A-2-1453
When the structure disclosed in No. 45 is applied to the manufacturing of the assembly, the slit-formed arm and the leaf spring or the armature must be joined, so that the slit portion is formed at the joining step or at that time. There is a problem that some of them may be deformed during other processes involved. As a result, the assembly has a large variation in dimensional accuracy.

[0005]

The present invention has been studied in order to solve the above-mentioned problems, and as a result, after an arm having a hole portion and a leaf spring are joined to an armature and heat treatment is performed, the armature is removed from the hole portion. By processing a slit, which is opened in the outer peripheral portion of the arm and to which the print wire is joined, the dimensional variation of the print wire joining position is reduced.
Furthermore, by inserting the print wire into the slit and brazing it, the entire outer circumference of the print wire can be covered and joined, increasing the joint area at the joint of the print wire and reducing the stress concentrated on the joint. On the other hand, the structure has high strength.

More specifically, according to the present invention, an arm having a hole near one end, an armature fixed to the other end of the arm, and an armature fixed to the opposite side of the arm. Characterized in that it is made of a printing wire brazed by being inserted into a slit opened from the hole portion of the arm to the outer peripheral portion of the arm. A print wire assembly.

[0007]

When the arm, the leaf spring, and the armature, which are hardened by the quenching and tempering process and have the slits processed in advance, and the armature are brazed, the arm and the leaf spring are partially softened by the influence of heat. Will end up. If quenching and tempering treatment is performed again to harden this, dimensional variation occurs. In particular, when the dimensional accuracy of the slit position becomes poor, the subsequent brazing work and assembling work of the printing wire become very complicated. Therefore, in the present invention, quenching and tempering treatment is performed after joining the arm, the leaf spring and the armature, and then the slit is processed to improve the dimensional accuracy. However, if the slit is processed after quenching and tempering, the processing load will be large.Therefore, make a hole of an appropriate size in the slit processing part in advance, and open this hole in the outer peripheral part of the arm. Makes processing easier. When the print wire is inserted into this slit and brazed, it is possible to receive impact force when printing on the entire outer circumference of the print wire, as compared to conventional products that receive force on one side of the outer circumference of the print wire. Therefore, the strength of the brazing joint can be significantly improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments and drawings. FIG. 1 shows an embodiment of a print wire assembly according to the present invention. The arm 1 was made of carbon tool steel SK5, and the hole 11 of the outer periphery and the slit processing portion was machined by press punching, and a hole was provided near the center of the entire arm length in order to reduce the weight of the assembly. .. Armature 2 has 49
% Co-2% V-Fe alloy was used to form the outer diameter by press punching, and then the groove to which the arm was joined was formed by cutting. The leaf spring 3 was formed by press punching a thin plate material of SK5, which is the same carbon tool steel as the arm 1. Next, the arm 1, the leaf spring 3, and the armature 2 were assembled. First, arm 1 in the groove of armature 2
72% Ag-28% after inserting and fixing leaf spring 3 on the opposite side
A Cu-based silver solder was used and heated to 800 ° C. for joining. At this time, the arm 1 and the leaf spring 3 made of SK5 were hardened only up to HV400. Therefore, in order to give a higher degree of utilization, quenching and tempering treatment was performed and hardness was adjusted for HV500. Quenching was performed at 800 ° C with water cooling, and tempering was performed at 180 ° C with air cooling.

Further, the hole portion 11 of the arm is formed in the outer peripheral portion 1 of the arm.
The slit opened to 2 was pressed. Then S
Prepare a printing wire 4 obtained by cutting a 0.3 mmφ hardened thin wire of KH51 into a predetermined length, insert this printing wire into the above slit, and join it with 50% Ag-20% Cu-based silver solder. did. The procedure for assembling the above print wire is shown in FIG. The print wire assembly of the present invention thus manufactured and the conventional print wire assembly shown in FIG. 5 were incorporated into a dot printer to perform a print test. Since the printing wire assembly of the present invention has high dimensional accuracy, the assembly work can be performed very smoothly when assembled, as compared with the conventional printing wire assembly. The results of the print test are shown in Table 1. When printing 100 million hours, the conventional print wire assembly had a breakage of 21% at the joint between the print wire and the arm, and an abnormality during peeling occurred. Did not happen.

[0010]

[Table 1]

[0011]

As described above, the conventional print wire assembly has many problems such as breakage and peeling due to the strong impact force due to ejection being concentrated on the joint portion of the print wire. In the printing wire assembly, the slit is formed in the arm, and the printing wire is inserted into this slit and brazed, so the joint area of the joint of the printing wire increases and the impact resistance and fatigue strength of the printing wire assembly are increased. And has excellent industrial properties such as no breakage or peeling. Further, the examination of the manufacturing process has an additional effect that the cost is reduced, the dimensional accuracy is increased, and a highly reliable printing wire assembly is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a print wire assembly according to the present invention.

FIG. 2 is a perspective view showing an assembling procedure of a print wire assembly according to the present invention.

FIG. 3 is a perspective view of a conventional print wire assembly disclosed in Japanese Patent Laid-Open No. 2-141254.

FIG. 4 is a perspective view of another conventional print wire assembly disclosed in Japanese Patent Laid-Open No. 2-145345.

FIG. 5 is a perspective view showing a most frequently used conventional print wire assembly.

[Explanation of symbols]

 1 Arm 11 Arm Hole 12 Arm Outer Part 2 Armature 3 Leaf Spring 4 Printing Wire

Claims (1)

[Claims] 1. An arm having a hole near one end thereof, an armature fixed to the other end of the arm, and a leaf spring fixed to the armature on the opposite side of the arm. A printing wire assembly, which has been subjected to quenching and tempering treatment, and which comprises a printing wire that is brazed by being inserted into a slit that opens from the hole of the arm to the outer periphery of the arm.