JPH0447031B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a treatment method for improving the mechanical properties of silicon steel.

[Prior art] In the printer head of a wire dot printer,
A printing lever is arranged at the rear end of the printing wire, and the printing lever is driven by magnetic attraction and repulsion to strike the printing wire, and printing is performed using this printing wire. The printing lever requires high magnetic permeability, high magnetic flux density, and low coercive force as magnetic properties.
Silicon steel and electromagnetic soft iron are used. Among them, silicon steel has excellent magnetic properties such as magnetic response, so it can be used for high-speed printing of printers, but silicon steel and electromagnetic soft iron have a base material hardness of 100 to 300 Hv on the Pickers hardness. Therefore, mechanical properties such as abrasion resistance must be improved in order to use it as a lever for hitting the printing wire as described above. However, since silicon steel cannot be subjected to surface carburizing and quenching or carbonitriding, nickel plating has conventionally been performed. This nickel plating is, for example, electroless plating containing an appropriate amount of boron or phosphorus, and the plating hardness is made to be about 700 to 1000 Hv by heat treatment after plating.

[Problem to be solved] However, a hardness of about 700 to 1000 Hv does not provide sufficient durability such as wear resistance, and is not suitable for parts that are subjected to strong impact force, such as printing levers, or parts that undergo repeated sliding movements. could not be used. When used in a printing lever, the rear end of a wire with a diameter of 0.3 to 0.2 mm cannot be directly struck, so a wire pin or the like is attached to the rear end of the wire to increase the diameter and the wire pin is struck. Therefore, in this case, the weight of the printing wire increases, which hinders an increase in printing speed and increases the cost of the printing wire.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a treatment method for improving the mechanical and magnetic properties of silicon steel.

[Means for Solving the Problems] In order to achieve the above object, the silicon steel treatment method of the present invention carburizes silicon steel with a silicon content of 2.8% to 6.5% to form a surface with a thickness of 20 to 200 μm. A solid diffusion treatment is performed to form a carburized layer of 2 to 10 μm on the surface of the silicon steel by embedding and heating the silicon steel in a mixed powder of powdered chromium, powdered vanadium, powdered titanium, or a combination of these and a catalyst. A carbide layer of the above-mentioned metal is formed with a thickness of .

[Examples] Hereinafter, specific examples of the present invention will be described in detail.

Commercially available silicon steel with a silicon content of 3% was used as the member to be treated, and a printing lever was manufactured that was driven by magnetic attraction and repulsion to directly impact the printing wire of the printer head, and was subjected to the following treatments.

Example 1 This printing lever was gas carburized at 850°C for 45 minutes.
A carburized layer with a thickness of 100 μm was formed.

Next, the carburized printing lever was embedded in a mixed powder containing appropriate amounts of powdered chromium, powdered alumina, and ammonium chloride, and solid diffusion treatment was performed at 1050° C. for 45 minutes in an argon stream.
Hereinafter, this processing method will be referred to as "processing condition B."

A chromium carbide layer with a thickness of 5 to 6 μm was formed on the surface of the printing lever treated under this treatment condition B, and the surface hardness was 1400 to 1700 Hv.

In addition, the printing lever on which the above 100 μm thick carburized layer was formed was heated to 90°C at 1050°C in an argon stream.
A solid diffusion treatment was performed to maintain the temperature. Hereinafter, this processing method will be referred to as processing condition C. According to this, a chromium carbide layer of 8 to 10 μm is formed on the surface of the printing lever, and the surface hardness is the same as when the processing time is 45 minutes.
It was 1400-1700Hv.

Under similar conditions, a 2 μm thick chromium carbide layer was formed on the surface when the treatment temperature was 1000° C. and the treatment time was 45 minutes.

FIG. 1 shows a comparison of the magnetic properties of products obtained under each treatment condition, with the horizontal axis representing the processing conditions and the vertical axis representing maximum magnetic permeability and coercive force. In this graph, processing condition A is vacuum magnetic annealing, which is conventionally commonly performed to improve the magnetic properties of silicon steel. be.

In the graph shown in Figure 1, if we compare the conventional treatment condition A with the treatment conditions B and C of the present invention, we find that under treatment conditions B and C, the maximum permeability increases and the retention It can be seen that the magnetic force has decreased significantly. In order to use it as a printing lever, the higher the maximum magnetic permeability, the better the magnetic properties, and the lower the coercive force, the better.
Both maximum magnetic permeability and coercive force were significantly improved, resulting in improved magnetic properties.

Example 2 A printing lever on which a 100 μm thick carburized layer was formed in the same manner as in the above example was buried in powdered vanadium, and solid diffusion treatment was performed under the same treatment conditions B and C as described above. Through this treatment, a vanadium carbide layer was formed on the surface, and a surface hardness of 2500 to 2800 Hv was obtained.

Example 3 A printing lever on which a 100 μm thick carburized layer was formed in the same manner as in the above example was buried in powdered titanium, and solid diffusion treatment was performed under the same treatment conditions B and C as described above. Through this treatment, a titanium carbide layer was formed on the surface, and a surface hardness of 3000 Hv was obtained.

In Figure 2, the horizontal axis shows the processing temperature and the vertical axis shows the maximum magnetic permeability, for silicon steels with different silicon components.
The graph shows the change in magnetic permeability when a printing lever with a 100 μm thick carburized layer formed in the same manner as in the above example was subjected to solid diffusion treatment for 45 minutes at treatment temperatures of 980°C, 1020°C, and 1050°C. It is something that For products using commercially available 3% silicon steel, the maximum magnetic permeability is significantly improved when heated to 1000℃ or higher and subjected to solid diffusion treatment, but for 2.5% and 1% silicon steels, the maximum magnetic permeability does not improve. Almost never seen. When the treatment method of the present invention is applied to silicon steel having a silicon content of 2.8% or more, preferably 3% or more, the magnetic properties are improved. Also, from this graph, it is clear that the processing temperature is 1000 to ensure sufficient solid diffusion processing.
It can be seen that a temperature of ℃ or higher is desirable.

In addition to the above examples, the treatment method according to the present invention is most suitable for surface treatment of parts such as magnetizing yokes that are required to have both sufficient magnetic properties and wear resistance.

In the present invention, the silicon component is 2.8% to 6.5%.
% silicon steel, as mentioned above, if the silicon content is less than 2.8%, good magnetic properties cannot be obtained, and as the silicon content increases, the magnetic properties improve, but 6.5% It is known that the maximum value is %, and as the amount of silicon content increases beyond that, the steel becomes brittle and becomes difficult to use.

The carburizing treatment can be carried out using various methods such as solid carburizing, liquid carburizing, and gas carburizing.

The thickness of the carburized layer is 20 μm to 200 μm.
If it is less than 200 μm, it will not be possible to replenish the amount of carbon needed to obtain the required amount of metal carbide during solid diffusion treatment, and if it is more than 200 μm, the carbon that has entered the silicon steel during carburization will be absorbed into the metal during solid diffusion treatment. This is because carbon that is not completely consumed in the carbide-forming reaction and is left over due to diffusion into the silicon steel remains at the grain interface, deteriorating the magnetic properties.

As for the metal used in the solid diffusion treatment, either powdered chromium or powdered vanadium or titanium powder may be used alone, or an appropriate mixture of these may be selected and used. Powdered ammonium chloride or the like is used as the catalyst.

The thickness of the metal carbide layer is 2 to 10 μm.
This is because if the thickness is less than 2 μm, sufficient mechanical properties cannot be obtained for use in parts that are subjected to strong impact forces or parts that undergo repeated sliding motions. 10μ to get
This is because m is sufficient.

[Effects] When silicon steel is treated by the treatment method of the present invention described above, the mechanical properties of its surface are sufficiently improved, and it can be made to have excellent magnetic properties.

[Brief explanation of the drawing]

Figure 1 is a graph comparing the magnetic properties of products under conventional treatment conditions A and treatment conditions B and C of the present invention, and Figure 2 is a graph showing the magnetic properties of products processed under various temperature conditions when silicon steels with different silicon compositions are treated. It is a graph showing a comparison of magnetic rates.

Claims (1)

[Scope of Claims] 1. Silicon steel with a silicon content of 2.8% to 6.5% is carburized to form a carburized layer with a thickness of 20 to 200 μm on the surface, and is treated with powdered chromium, powdered vanadium, powdered titanium, or a combination thereof. A silicon steel characterized in that a carbide layer of the metal with a thickness of 2 to 10 μm is formed on the surface of the silicon steel by performing a solid diffusion treatment of embedding and heating the silicon steel in a mixed powder with a catalyst. Processing method.