JPH0513748U - Wire dot print head - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the leaf spring from warping due to heat generated during laser welding, and to enable stable operation without variations in characteristics. [Structure] Located between a plate spring 1, a spacer 10, a laser melting portion 21 that is melted by being irradiated with a laser for laser welding the armature yoke 9 and the like, and a plate spring supporting end 1a of the plate spring 1. A stress relief portion 22 is provided at a location, and when the laser melting portion 21 is solidified when laser welding is performed, the stress relief portion 22 absorbs the stress generated by the different cooling rates during cooling. Then
The stress is prevented from being transmitted to the leaf spring supporting end 1a of the leaf spring 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a wire dot print head, and is particularly suitable for a wire dot print head that performs printing by driving a print wire fixed to the tip of an armature.

[0002]

[Prior Art]

 As is well known, there are various types of wire dot print heads such as plunger type and clapper type, but recently spring charge type has become the mainstream because of its good high-speed response. In the spring charge type wire dot print head, an armature to which a wire is fixed is swingably supported by a leaf spring for biasing, and the armature is cored by a permanent magnet against the elastic force of the leaf spring in advance. When the printing is performed, the coil wound around the core is excited to generate a magnetic flux in the direction opposite to that of the permanent magnet to open the armature.

FIG. 4 is a sectional view of a conventional wire dot print head. In FIG. 4, reference numeral 1 is a leaf spring for biasing which swingably supports the armature 2, and 3 is a wire for hitting a print medium through an ink ribbon to print. Next, 4 is a wire guide for guiding the print wire 3 to form a track, which is formed in front of the guide frame 5 in the print direction and accommodates the guide felt 6 therein.

A coil 7 is wound around a core 8 and excited by energization. A coil 8 is arranged so as to face the leaf spring 1. A coil 7 is excited to attract the armature 2. A coil 9 is adjacent to the armature 2. An armature yoke, 10 is a spacer, 11 is a magnet yoke, 12 is a permanent magnet, 13 is a ring, and 14 is a base. Further, 15 is a printed circuit board, 16 is a coil bobbin, 17 is a coil terminal, 18 is a cap, 19 is an insulating plate, and 20 is a clamp spring for clamping and fixing the above-mentioned laminated members.

Now, the operation of the wire dot print head will be briefly described. First, when the coil 7 is excited, the magnetic flux of the permanent magnet 12 passes through the magnet yoke 11, the spacer 10, the armature 2, the core 8, the base 14 and the ring 13 to generate a magnetic attraction force, which causes the armature 2 to move into a leaf spring. 1 is attracted to the core 8 while being biased.

Next, when the coil 7 is excited in this state, the magnetic flux of the coil 7 cancels the magnetic flux of the permanent magnet 12 and the leaf spring 1 in the biased state is released. As a result, the print wire 3 joined and fixed to the tip of the armature 2 is driven, and printing is performed by hitting the print medium via the ink ribbon.

Stable and satisfying the performance required to perform the printing operation described above, for example, the repetition time of the printing wire 3, the force with which the printing wire 3 presses the ink ribbon or the printing medium, the so-called printing force, etc. In order to perform the above printing, the leaf spring 1 must be securely fixed and supported between the armature yoke 9 and the spacer 10 as shown in FIG. However, in order to obtain the above-mentioned fixed supporting force, the crimping force of the clamp spring 20 alone is insufficient. Therefore, as shown in FIG. 5, the leaf spring 1 is laser-welded together with the armature yoke 9 and the spacer 10 to integrate them. Here, the integrated leaf spring 1, armature yoke 9, spacer 10 and armature 2 which is laser-welded to the leaf spring 1 at the same time, and the printing wire 3 fixed to the armature 2 are collectively referred to as a leaf spring assembly.

[0008]

[Problems to be solved by the device]

 However, in the leaf spring assembly configured as described above, the leaf spring 1 warps due to thermal deformation during laser welding, which is a major cause of variations in printing characteristics and poor printing. The cause of the above-mentioned warpage will be described in detail below. FIG. 7 is an enlarged view of the laser melting section. The portion melted by the laser shot is then cooled rapidly and solidified while undergoing heat shrinkage. By the way, the cooling rate is highest at the portion close to the armature yoke 9 having a large heat capacity, and slower at the spacer 10 side. Therefore, after the melted portion on the armature yoke 9 side is solid, the melted portion on the spacer 10 side is cooled and heat-contracted to pull the spacer 10 and the leaf spring 1, so that the spacer 10 and the leaf spring 1 are As shown in FIG. 6, which is a cross-sectional view taken along the arrow A, it solidifies in a state of being warped toward the core 8 side.

The warp remains even after the clamp spring 20 is integrated into a unit, and as shown in FIG. 8B, the armature yoke 9 and the spacer 10 can fixedly support the leaf spring 1 only near the laser welded portion. become. It is difficult for such a leaf spring 1 to perform an operation for satisfying the required performance. Further, since the warped state is not uniform, there is a problem in that variations occur among the leaf springs, variations in printing characteristics occur, or printing defects are affected. In view of the above-mentioned problems, the present invention provides a print head capable of preventing the leaf spring from being warped due to heat generated during laser welding, allowing stable operation without variations in characteristics. The purpose is to

[0010]

[Means for Solving the Problems]

 The wire dot print head of the present invention has a leaf spring assembly formed by laser welding a leaf spring, a spacer, and an armature yoke. In the wire dot print head, the leaf spring, the spacer, and the armature yoke are laser-welded. A stress relief portion is provided at a position located between the laser melting portion irradiated with the laser for the purpose and the supporting end of the leaf spring.

[0011]

[Action]

 By providing a stress relief portion at a position located between the laser melting portion to which a laser for laser welding the leaf spring, the spacer, and the armature yoke is irradiated and the supporting end of the leaf spring, The stress generated when the cooling rate of the melted portion when laser welding is performed is different due to the above-mentioned leaf spring, spacer, armature yoke, etc. is absorbed in the stress relief portion, so the above-mentioned stress is applied. It will not be transmitted to the supporting end of the spring.

[0012]

【Example】

 FIG. 1 is a perspective view of a leaf spring assembly showing an embodiment of the wire dot print head of the present invention. As is apparent from FIG. 1, the leaf spring assembly is constructed by joining the leaf spring 1 and the spacer 10 by laser welding. In the present embodiment, the leaf spring 1 and the spacer 10 are provided with a stress relief portion 22 between a portion which is irradiated with laser and melted, that is, between the laser melting portion 21 and the leaf spring supporting end 1a. Has been.

The stress relief portion 22 is formed of a through hole as shown in FIG. 2 which is a sectional view taken along the line AA in FIG. 1, and is formed by laser welding when laser welding is performed. It has the function of preventing the stress due to thermal contraction when the unwinding portion 21 cools from reaching the flexible portion of the leaf spring 1. Therefore, in the case of the wire dot print head of the present embodiment, when the melted portion is cooled during laser welding, the cooling rate varies depending on each member constituting the leaf spring assembly, so that the plate is deformed due to thermal deformation. It is possible to prevent the spring 1 from warping.

That is, when the laser welding is performed as described above, as shown in the enlarged view of the laser melting portion in FIG. 7, the melted portion is then rapidly cooled and solidified while performing heat shrinkage. . In this case, the cooling rate is highest in the portion close to the armature yoke 9 having a large heat capacity as described above, and slower on the spacer 10 side. Therefore, after the laser melting portion 21 on the armature yoke 9 side is solidified, the laser melting portion 21 on the spacer 10 side is cooled and thermally contracted, and the spacer 10 and the leaf spring 1 are pulled. Therefore, conventionally, the spacer 10 and the leaf spring 1 are solidified in a state of being warped toward the core 8 side as shown in FIG. 6, so that the leaf spring 1 is warped.

On the other hand, in the wire dot print head of this embodiment, since the stress relief portion 22 is provided between the laser melting portion 21 and the plate panel supporting end 1a, the spacer 10 and the armature yoke 9 are The stress generated by the difference in the thermal contraction speed when the laser welding is performed can be released by the stress relief portion 22, and the inconvenience that the leaf spring 1 is warped can be surely prevented. Therefore, it is possible to eliminate variations in the characteristics of the print head, and it is possible to perform stable operation for all wire dot print heads.

FIG. 3 shows the dimensions of each part of the leaf spring assembly of this embodiment. In FIG. 3, the laser through hole 23 provided in the laser melting portion 21 is formed to have a diameter of about 0.4φ to 0.7φ. In FIG. 3, a dimension a is a length of a portion where the leaf spring 1, the armature yoke 9 and the spacer 10 are superposed, and a = 5 to 8 mm. Further, the dimension b is the width of the laser melting portion 21, and b is about 1.5 mm. Further, the dimension c is a distance for separating the stress relief portion 22 from the laser melting portion 21, and it is desirable that the distance c is 0.5 mm or more. Therefore, the range e where the stress relief portion 22 is formed is a range of about 2 to 5 mm. Therefore, if a stress relief portion having an appropriate size is formed at this position, the stress generated in the laser melting portion 21 will be reduced. It is possible to absorb and prevent the leaf spring 1 from warping. In addition, in the above-mentioned embodiment, the example in which the through hole is provided to configure the stress relief portion 22 is shown, but the above stress relief portion 22 does not necessarily have to be the through hole, and is formed in a groove shape. Can release stress well.

[0017]

[Effect of the device]

 As described above, according to the present invention, the stress relief portion is provided at a portion located between the leaf spring supporting end and the portion which is melted by being irradiated with the laser for welding the leaf spring, the spacer, the armature yoke and the like. Therefore, the stress generated by the difference in the cooling rate of the portion melted when laser welding is performed, such as the leaf spring, spacer and armature yoke, can be absorbed by the stress relief portion. . As a result, it is possible to prevent the stress generated during laser welding from being transmitted to the leaf spring supporting end and prevent the leaf spring from warping. The dot print head can be operated stably.

[Brief description of drawings]

FIG. 1 is a perspective view of a leaf spring assembly showing an embodiment of a wire dot print head according to the present invention.

FIG. 2 is a cross-sectional view of a leaf spring assembly.

FIG. 3 is a dimensional explanatory view of each part of the leaf spring assembly.

FIG. 4 is a cross-sectional view of a conventional wire dot print head.

FIG. 5 is a perspective view of a conventional leaf spring assembly.

FIG. 6 is a sectional view of a conventional leaf spring assembly.

FIG. 7 is an enlarged explanatory view of a laser welded portion.

FIG. 8 is a diagram showing deformation by a leaf spring after pressure bonding by a clamp spring.

[Explanation of symbols]

 1 leaf spring 2 armature 3 printing wire 9 armature yoke 10 spacer 21 laser melting part 22 stress relief part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Takanori Mimura 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A wire dot printing head having a leaf spring assembly formed by laser welding a leaf spring, a spacer, an armature yoke, and the like, wherein a laser for laser-welding the leaf spring, the spacer, the armature yoke, and the like is irradiated. A wire dot printing head, wherein a stress relief portion is provided at a position located between the laser melting portion and the supporting end of the leaf spring.