JPH0337509B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to printing members such as platens, type wheels, type drums, etc. in printing devices such as printers and typewriters.

[Prior Art and Problems to be Solved] Conventionally, printing devices have used printing members such as plastic platens, type wheels, and type drums.

Some of these printing members are constructed only from plastic molded products, but these have the disadvantage of poor abrasion resistance.

There are also plastics that are filled with whiskers such as silicone carbide to improve wear resistance, but they have the drawback of being expensive.

Therefore, in order to improve wear resistance and keep costs low, some plastic molded products are plated with metal.

For example, there is a method in which copper plating is applied to the surface of a base material made of epoxy resin or ABS resin to a thickness of about 5 to 10 μm, and then a single layer of nickel or nickel rim plating is applied to a thickness of 20 to 40 μm. Note that this copper plating serves as a buffer layer. However, in the case of nickel electrolytic plating,
There is a drawback that so-called surface sagging occurs around the plating area, resulting in poor print quality. Furthermore, when electroless nickel-phosphorus plating is performed, the plating speed is slow, so it takes time to obtain a thick plating layer, resulting in poor productivity. If the hardness is on the order of nickel or nickel-phosphorus alloy, there is a limit to the improvement in wear resistance, and the amount of wear increases in proportion to the number of printings, making it unusable, making it difficult to extend the service life.

Therefore, in order to further improve wear resistance, copper plating is applied to the surface of the plastic molded product, and on top of that, nickel plating is formed to a thickness of about 30 μm, and then chrome plating, nickel/boron alloy plating, or nickel/boron/tungsten alloy plating is applied on top of that. There are some that form a high hard metal plating layer such as plating. The hardness of the surface high hard metal plating layer is Hv=700
~1200, and has excellent wear resistance. However, in this case, since the pressure applied from the outside due to printing acts directly on the hard metal plating layer, cracks are likely to occur in the relatively brittle hard metal plating layer, and as the printing operation continues, these cracks progress until finally. It has a limited lifespan because it peels off.

[Object of the Invention] Therefore, an object of the present invention is to provide a printing member for a printing device that has sufficient wear resistance, is less prone to cracking, and has a low manufacturing cost.

[Means for achieving the object] In order to achieve the above object, the printing member of the printing device according to the present invention includes a first plating layer of a medium-hard metal formed on the surface of a base material made of plastic;
It has a second plating layer of a high hard metal formed on the first plating layer, a third plating layer of a medium hard metal formed on the second plating layer, and a third plating layer of a medium hard metal formed on the second plating layer.
The hardness of the plating layer and the third plating layer is Hv=300~
600, and the hardness of the second plating layer is Hv=700 ~
1200.

[Function] When printing is performed using the printing member of the printing device according to the present invention, the first and second plating layers of medium-hard metal, which are formed so as to be sandwiched between the second plating layer of high-hard metal, Since each acts as a buffer layer that disperses printing pressure, cracks are less likely to occur in the second plating layer, which is made of a highly hard metal. In addition to being excellent in crack resistance, sufficient wear resistance is obtained due to the presence of the second plating layer made of a highly hard metal, and the printing member can have an extremely long life.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

This embodiment is an example in which the present invention is applied to a platen as an example of a printing member. As shown in FIG. 1, the platen 1 has a plurality of protrusions 2 on its outer periphery. A printing hammer 3 is provided opposite the platen 1. When the printing hammer 3 is driven by a drive source (not shown), it comes into contact with the protrusion 2 via the ink ribbon 4 and the paper 5. At this time,
Dots (not shown) are formed on the paper 5 by the ink ribbon 3. This dot makes the characters,
A figure is formed.

Next, the platen 1 which is a printing member according to the present invention
This will be explained with reference to FIG. The base material 6 of this platen 1 is molded from plastic such as epoxy resin or ABS resin. On this base material 6, a copper base plating layer 7 is formed with a thickness of 5 to 15 μm. The copper base plating layer 7 functions as a buffer layer, but may be omitted depending on the case.

A first plating layer 8 of medium hard metal is formed on the base plating layer 7 to a thickness of 5 to 20 μm. The hardness of this first plating layer 8 is Hv=300 to 600,
Practically, electrolytic nickel metal (Hv=300~
600) and nickel phosphorus electroless plating (Hv=500
~600) etc. are used.

A second plating layer 9 made of a highly hard metal is formed on the first plating layer 8 to a thickness of about 5 μm. The hardness of the second plating layer 9 is Hv=700 to 1200, and practically, chrome plating, nickel/boron alloy plating, nickel/boron/tungsten alloy plating, etc. are used.

Further, on this second plating layer 9, a third plating layer 10 of medium hard metal is formed with a thickness of 10 to 20 μm. As for the material, electrolytic nickel plating or nickel phosphorus electroless plating is used as in the first plating layer.

FIG. 3 shows a graph comparing the durability of the platen of this embodiment and a conventional platen. In the drawings, the thin solid line indicates a plastic molded product with nickel plating (hereinafter referred to as "Conventional Example A"), and the broken line indicates a plastic molded product with nickel plating, and then chrome plating of about 10 μm on top ( (hereinafter referred to as "conventional example B")
It is. The thick solid line is the platen of this embodiment.

As is clear from this graph, in Conventional Example A, the amount of wear increases significantly in proportion to the number of printings.
If the amount of wear exceeds the usable range, the printing member becomes unusable and its lifespan is shortened.

Furthermore, in Conventional Example B, since the surface layer is a hard metal plating layer, it has excellent abrasion resistance, and even if the number of printing increases, the amount of abrasion is extremely small. However, printing pressure is directly applied to the brittle, highly hard metal, and this pressure propagates from the point hit during printing to the surrounding area, causing cracks. A nickel plating layer is provided below the high hard metal plating layer,
This lower nickel layer alone was not able to sufficiently buffer the printing pressure, and cracks occurred after about 100,000 printings, and eventually the plating layer peeled off, making it unusable. In this way, even in conventional example B, a long life is impossible.

On the other hand, according to the platen according to the present invention, even if the third plating layer 10 made of medium-hard metal is partially worn out at the printed portion (in this embodiment, the tip of the protrusion 2), the periphery of the printed portion remains intact. remains. The printing pressure applied to the printing part propagates from there to the surroundings, but the propagating pressure is buffered by the first plating layer 8 and the remaining third plating layer 10.
The force applied to the second plating layer becomes smaller. That is, the printing pressure applied to the printing part is not so much transmitted to the surrounding high-hardness metal, but is dispersed to the first plating layer 8 and the third plating layer 10. Therefore, cracks are less likely to occur in the second plating layer 9 of high hard metal.

In addition, the platen of the present invention can be used for a long period of time.
3rd place in the part of the printing part where the number of printing is large.
The plating layer 10 is worn out, and the second plating layer 9
is partially exposed. Since this second plating layer 9 is made of a highly hard metal, the degree of wear is extremely small. Therefore, as shown in Fig. 3, after the number of printing increases to a certain extent, the increase in the amount of wear is suppressed to a very small extent, so the wear resistance is extremely good compared to conventional example A, and there is no deterioration in print quality. Extremely small.

As mentioned above, the wear of the third plating layer 10 occurs partially in the printed area,
The third plating layer 10 remains around the printed area,
Since the printing pressure is buffered, the occurrence of cracks can be reduced.

As described above, according to the present invention, the occurrence of cracks can be suppressed, so that the device can be used for a long period of time.

The present invention can also be applied to printing members other than platens. In this case as well, similar to this embodiment, by using the sanderch structure in which the second plating layer of high hard metal is sandwiched between the first and third plating layers of medium hard metal, the crack resistance is good and the overall The plating thickness can be reduced, and surface sag can be minimized.

[Effect] In the printing member of the printing device according to the present invention, the first and third plating layers made of medium-hard metal act as buffer layers against printing pressure, so cracks are less likely to occur in the second plating layer made of high-hard metal. Become. In the printing area, the first plating layer is partially worn away and the second plating layer is partially worn away.
Even if the plating layer is exposed, the printing pressure is distributed not only to the exposed second plating layer to the underlying first plating layer but also to the third plating layer remaining around the printed portion. Therefore, the pressure exerted on brittle, highly hard metals can be reduced and cracks are less likely to occur. Further, the second plating layer of high hard metal provides sufficient wear resistance.

As described above, according to the present invention, the printing member can have an extremely long life.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a partially enlarged sectional view of FIG. 1, and FIG. 3 is a graph showing the durability of the conventional example and the embodiment of the present invention. 1... Printing member (platen), 6... Base material, 8
...First plating layer, 9...Second plating layer, 10...
...Third metal layer.

Claims (1)

[Scope of Claims] 1. A first plating layer of a medium-hard metal formed on the surface of a base material made of plastic; a second plating layer of a high-hard metal formed on the first plating layer; A third plating layer of medium hard metal is formed on the second plating layer, and the first plating layer and the third plating layer have hardness.
A printing member for a printing device, characterized in that Hv=300 to 600, and the second plating layer has a hardness of Hv=700 to 1200. 2 The medium-hard metals mentioned above are nickel or nickel.
2. The printing member of the printing device according to claim 1, wherein the high hard metal is made of phosphorus alloy, and the high hard metal is made of chromium, nickel-boron alloy, or nickel-boron-tungsten alloy.