JPH0440933Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of application of the invention] The invention moves a hammer bank that holds a plurality of dot printing hammers spaced apart along a printing line, and reciprocates along the printing line. This relates to a printing hammer used in dot printers that print in the process of printing.

[Background of the idea]

In such a dot printer, in order to enable high-speed printing, a set of N printing hammers is installed with the printing pins shifted, for example, by one dot line in a direction perpendicular to the digit direction. A printing method has been proposed in which N dot lines are printed simultaneously.

An example of this printing hammer is shown in FIG. A printing hammer 20 made of a plate spring 22 has a printing pin 4 attached to its upper end and a plunger 6 attached to its center.
The printing hammer 20 is attracted and held in a bent state by a permanent magnet on a pole (both not shown). As described above, the printing pins 4 are mounted one dot line apart. That is, the lengths of the leaf springs 22 of each printing hammer 20 are different. Therefore, the equivalent mass m and spring constant k of the printing pin 4 portion of each printing hammer 20 are different, and as a result, the natural frequencies are also different.

Therefore, the characteristic values of each printing hammer 20 are different,
There is a problem that the printing density is different for each printing hammer 20 and the printing quality is degraded, and the printing cycle is
Since it is determined in accordance with the printing hammer 20 having a small natural frequency, it has the disadvantage that the characteristics of other printing hammers 20 cannot be effectively utilized.

[Purpose of invention]

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, make the characteristics of each printing hammer almost the same, and thereby stabilize printing quality.

[Summary of the idea]

This invention focuses on the fact that changing the position of the printing pin changes the length of the leaf spring, causing a difference in the natural frequency. This is characterized in that by changing the width, the natural frequencies of all printing hammers are made equal. The present invention will be described below with reference to embodiments.

[Example of idea]

FIG. 1 shows an embodiment of the printing hammer of the present invention.
Leaf springs 12 ₁ , 12 2 and ₁ of the left printing hammer 10 1 , _the center hammer 10 ₂ and the right hammer 10 ₃ respectively
The lengths of 2 ₃ are (L-l), L, and (L+l), respectively.・The equivalent mass and spring constant of each printing hammer 10 at the position of the printing pin 4 are m ₁ , m ₂ ,
When m ₃ and k ₁ , k ₂ , and k ₃ are used, the relational expression m ₁ <m ₂ <m ₃ holds true. That is, as the length of the leaf spring 12 increases, the equivalent mass increases. In order to equalize the natural frequencies of all printing hammers 10, it is necessary to establish the relational expression k ₁ /m ₁ = k ₂ /m ₂ = k ₃ /m ₃ , and k ₁ < k ₂ < k _3. There must be. That is, if the length of the leaf spring 12 becomes longer, the spring constant k must be increased by that amount. The spring constant k is expressed as k=(W·t ³ ·E)/(4·α·L ³ ). Here, W is the width at the base of the leaf spring 12, t is the thickness of the leaf spring 12, and E is the width of the leaf spring 12.
L is the length of the leaf spring 12, α is the shape coefficient determined by the shape of the leaf spring 12, α=3/(1-β){3/2-1/(1- β)
It is expressed as [β/(1-β)] ² LOGβ}. Here, β is β=w/W, where w is the width of the tip of the leaf spring 12.

Therefore, the relationship between the widths of the root portions of each leaf spring 12 is W ₁ <W ₂ <W ₃ .

In this way, when the length L of the leaf spring 12 becomes longer, the width W of the root part is increased by that amount to k/m.
By keeping the ratio constant, the natural frequencies of each printing hammer can be made equal.

In the above embodiment, in order to change the shape of the leaf spring 12 in accordance with the height of the printing pin 4, not only the thickness but also the width of the base part is changed.The reason for this will be briefly explained.

Such a hammer 10 includes, for example, six leaf springs 10.
consists of one board (hereinafter referred to as a 6-board set)
is commonly practiced. In other words, six leaf springs are formed with a common lower end. A leaf spring is made by etching a single plate into its shape, then polishing it to a predetermined thickness. Therefore, in the case of a set of 6 sheets, in order to change the thickness according to the height of each printing pin, it is necessary to use a grindstone with steps that correspond to changes in the thickness of the leaf spring during polishing. This will reduce work efficiency.

In addition, when forming leaf springs one by one, the thickness variation ranges from a few microns to several tens of microns at most, making it difficult to manage and when fixing the leaf springs during assembly. Also, it is necessary to provide a step according to the change in the thickness of the leaf spring, which makes assembly difficult.

There are many problems in changing the plate thickness in this way.
On the other hand, changing the width of the root can be done by simply changing the etching type, making the polishing work more efficient and eliminating the need to provide a step on the plate spring fixing member, which improves the processing and assembly surfaces. There are many advantages as well. For this reason, I try to change the width of the root rather than the thickness.

[Effect of idea]

As explained above, according to the present invention, since the characteristics of each printing hammer can be made the same, it is possible to improve printing quality. Another advantage is that the characteristics of the printing hammer can be effectively utilized.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the printing hammer of the present invention, and FIG. 2 is a front view showing an example of a conventional printing hammer. In the figure, 10 and 20 are printing hammers, 12 and 22 are leaf springs, 4 is a printing pin, and 6 is a plunger.

Claims (1)

[Claims for Utility Model Registration] 1. Printing hammers made of leaf springs with printing pins attached to their upper ends are arranged in the digit direction, and the printing pins are provided at predetermined distances apart in a direction perpendicular to the digit direction. A printing hammer for a dot printer, characterized in that the shape of a leaf spring constituting the printing hammer is changed in accordance with the height of the printing pin, so that the natural frequencies of all the printing hammers are made equal. 2. The printing hammer for a dot printer according to claim 1, which is a registered utility model, characterized in that the width of the base of the leaf spring is changed in accordance with the height of the printing pin.