JPS5844151B2 - Method of applying strain relief annealing anti-seizure coating to electromagnetic steel sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a film on an electromagnetic steel sheet to prevent seizure mainly during strain relief annealing.

Conventionally, so-called silicon steel sheets containing silicon and pure iron-based electromagnetic steel sheets containing no silicon have been used as electromagnetic steel sheets for motor transformers and the like.

These electromagnetic steel sheets were coated with an insulating coating to reduce eddy current loss, improve punchability (when sheared), corrosion resistance, and prevent seizure during strain relief annealing.

However, in recent years, there has been a tendency to use polished steel sheets as these electromagnetic steel sheets with the aim of drastically reducing costs.

In this case, the polished steel sheet is used after continuous annealing or batch annealing in the manufacturing process of the polished steel sheet to give hardness to improve the punchability of the steel sheet, and to cause recrystallization and grain growth during strain relief annealing. Temper rolling of about 0.2 to 10% is performed.

Also, in the case of conventionally used electromagnetic steel sheets, semi-processed materials are used, which are shipped as temper-rolled materials and subjected to stress relief annealing after punching at the customer.

In both of these cases, since there is no insulating film applied to the surface of the electromagnetic steel sheet, the iron core seizes during strain relief annealing after punching, deteriorating the magnetic properties, and requires work to remove the seize. Because of this requirement, efficiency decreased and became a problem.

Therefore, the methods conventionally considered to deal with these seizure problems are: ■ Applying refractory to the iron stone after punching, ■ Removing the seizure by mechanical methods during vibration and bending, ■ Applying refractory material to the steel plate surface. These methods include providing roughness to create gaps to make it easier to peel, and (1) passing the sheets one by one in a continuous annealing furnace for strain relief annealing.

However, these methods (1) have problems with workability because they are applied to the iron core, and since the coating agent is refractory, the space factor and appearance after annealing are inferior, and (2) the equipment cost is high and there is also a problem with distortion. There is a danger that the magnetism will be degraded due to the risk of foreign substances entering the magnetic field.

For this reason, there has been a desire for a method that is inexpensive and can prevent image sticking.

As a result of various studies to meet this demand, the inventors of the present invention have found that a coating is effective to prevent seizure during strain relief annealing on the surface of a steel sheet on the entry side of continuous annealing or batch annealing in the manufacturing process of electromagnetic steel sheets. It has been found that the above requirements can be fully met by applying a treatment solution that generates a coating, performing continuous annealing or batch annealing and simultaneous film baking, and then skin-pass rolling in the presence of rolling oil that has rust-preventing properties. It is something.

Such surface-treated electromagnetic steel sheets are punched or sheared into predetermined cores by customers, and then subjected to strain relief annealing to be used as iron cores for motors and transformers.

The gist of the invention is as follows.

When manufacturing electromagnetic steel sheets by annealing and temper rolling cold rolled steel sheets, an aqueous solution containing an inorganic colloid substance is applied to the surface of the cold rolled steel sheets before the annealing, and then annealing is performed, during which time the film is fired. 0.02~0.8? /rn
A strain-relieving annealing anti-seizure coating is applied to an electromagnetic steel sheet, which is characterized by forming a sintered coating and then temper-rolling the sintered coating using a rolling oil having anti-corrosion properties after annealing. How to rub.

In this way, according to the present invention, an aqueous solution of an inorganic colloidal substance capable of forming an anti-seizure film during strain relief annealing is applied and dried on the entrance side of continuous annealing or batch annealing, and the amount of the deposited film is limited. It can sufficiently withstand 0.2 to 10% temper rolling and prevent seizure during strain relief annealing.

Furthermore, since a rolling oil having a particularly rust-preventing ability is used during this temper rolling, rusting is sufficiently prevented until the end of the punching process by the customer, despite the use of an inorganic colloidal substance alone. be.

In addition, since the aqueous solution for forming the anti-seize film is applied before continuous or batch annealing in the manufacturing process of electromagnetic steel sheets, and the film is fired using an annealing furnace, a special There is no need for a film firing furnace, and the process can be performed at low cost with a large energy saving effect.

Furthermore, in order to impart corrosion resistance to the film, it is usually considered to use chromic acid or phosphoric acid or their salts in combination, but these combinations are undesirable in terms of pollution, but in the present invention, the sole use of an inorganic colloidal substance is considered. So there is no need to worry about that.

An example of the implementation process of the present invention will be explained below with reference to FIGS. 1 and 2.

Figure 1 shows an example of application to a continuous annealing process, where 1 is a cold-rolled electromagnetic steel sheet coil, an electrolytic degreasing tank 2 and a scrubber 3.
It is cleaned with a blower 4, dried with a blower 4, and heat-treated in a continuous annealing furnace 5.

Thereafter, it is once wound into a coil 6, followed by temper rolling of about 0.2 to 10% in a temper rolling mill 7, wound into a coil 8, and shipped.

In such a normal process, an aqueous solution coating device A (a dipping tank 9 and a squeezing roll 10) is installed on the inlet side of the continuous annealing furnace 50, and this device A coats an aqueous solution containing an inorganic colloidal substance.

Fig. 2 shows an example of application to a batch annealing process, in which after drying with blower 4, coating and drying device
), the treatment liquid is applied and dried, the coil 6 is wound up, and the coil 6 is annealed in a batch annealing step 12.

In both FIGS. 1 and 2, after annealing, adjustment rolling is performed in a temper rolling mill 7 in the presence of rolling oil having antirust properties.

What is extremely important in carrying out the method of the present invention is that the coating applied and fired during annealing should sufficiently withstand the subsequent temper rolling, that it should sufficiently prevent seizure during strain relief annealing, and that it should be sufficiently prevented from being hammered by customers. Rust should not occur until punching.

In general, it is desirable that the amount of coating be large to some extent in order to prevent seizure during strain relief annealing, while on the other hand, it is better that the amount of coating be small in order to withstand 02 to 10% temper rolling.

As a result of various studies on the balance between the two, we found that it varies somewhat depending on the skin reduction ratio of skin pass rolling, but the film before skin pass rolling is between 0.02 and 0.8'. /m'' was found to be good.

The reason for this is that the steel plates with a film formed on them are laminated to produce a weight of 20kg/cm.
When processed under strain relief annealing conditions in the pressurized state of 4, it is recognized that there is no problem with practical seizure if the amount of seizure is less than about 100 S'/crA, and the amount of film is less than 0.02 f/i. The amount of burn-in will be greater than the above value, and there will be concerns about burn-in.

On the other hand, if the film amount exceeds o, sP/m, the film will peel off in a 5% skin bath.

The relationship between the above-mentioned annealing film amount and various effects is shown in Example Table 1.2.

In the present invention, one or more of colloidal alumina (alumina sol), colloidal silica, colloidal titanium, purified bentonite, and artificial mica are used as the inorganic colloidal substance for stringing the processing liquid. .

However, the film formed on the treatment solution was
Compared to the method described in Japanese Patent No. 152833, which contains chromic acid, phosphoric acid, or their salts, the film-forming ability is inferior, the film peels off during temper rolling, and the corrosion resistance is poor. In the present invention, rust is prevented until the customer punches by using a rolling oil having anti-corrosion properties during skin pass rolling.

In addition, by temper rolling using these anti-rust oils,
It has become possible to perform temper rolling without peeling even when the inorganic colloidal substance is used as a single coating.3 In this case, the rolling oil used is a medium or equivalent to P-7 or P-8 of the U.S. military rust preventive oil P series. A light anti-rust oil is used.

The aqueous solution may be applied by commonly used methods such as spraying and roll squeezing.

Since rolling oil with anti-corrosion properties is present on the fired film obtained by the present invention, this acts as a lubricant during punching, and has the advantage of omitting punching lubricating oil, as well as the conventional method. Since the amount of film is smaller than that of an insulating film, punching performance is not hindered and several hundred punching and punching cycles can be obtained.

Example 1 Steel containing 0.2% Si was hot rolled to a thickness of 2.3 x m, pickled and cold rolled to 0.5 gm.

When this material is processed in the process shown in Figure 1, it is electrolytically degreased with 3% sodium orthosilicate, washed with water using a scrubber, and dried.
At the entry side of the continuous annealing furnace, an aqueous solution that produces the two types of anti-seizure coatings shown in Table 1 is applied, squeezed with a roll, annealed at 600°C for 4 seconds in the continuous annealing furnace, and fired at the same time as the first coating. Various coating amounts were used as shown in the table.

After that, Noxlast 530-40 (equivalent to P-8) (manufactured by Barker Kosan) was used as a rolling oil with anti-rust properties during temper rolling.
It was rolled by 5% using.

The surface roughness of the film was 1.0μ in Hmax.

This was punched and laminated to the motor core without punching oil.
Strain relief annealing was performed at 80° C. for 2 hours in 8% H2, 92% N2.

The results are shown in Table 1.

Example 2 Rimmed steel was hot rolled to a thickness of 2.3mm, pickled and cold rolled to a thickness of 0.5mm.

Before processing this material in the process shown in Figure 2, it is electrolytically degreased with 3% Oron sodium silicate, washed with water using a scrubber, dried, and then coated with an aqueous solution that produces the three types of anti-seize films shown in Table 2. The mixture was squeezed with a roll, dried, and wound into a coil.

This coil was annealed in a batch annealing furnace at 8.00° C. for 5 hours and at the same time the coating was fired to give various coating amounts as shown in Table 2.

Thereafter, it was temper-rolled by 5% using Dufney Oil Coat A7 (manufactured by Idemitsu Oil Co., Ltd.) (equivalent to P-7) as a rolling oil.

The surface roughness of the film was 0.8μ in Hmax.

After punching and stacking this on the motor core without punching oil, 7
Strain relief annealing was performed at 50°C for 2 hours in N2.

The results are shown in Table 2. As detailed above, according to the present invention, the aqueous solution according to the present invention is applied at a specific position (input side of batch or continuous annealing) in the manufacturing process of electromagnetic steel sheets, and the coating is fired at the same time as the dry steel sheet is annealed. A film can be formed to prevent seizure during strain relief annealing, and this film can withstand the subsequent skin-pass rolling, making it possible to perform processes that include skin-pass rolling. Due to the rust-preventing power, there is no rusting during the punching process by the customer, and the use of punching oil can be omitted, and furthermore, seizure can be effectively prevented during strain relief annealing.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are process diagrams for implementing the present invention. A and B are treatment liquid coating and drying devices.

Claims (1)

[Claims] 1. When manufacturing electromagnetic steel sheets by annealing and skin-pass rolling cold rolled steel sheets, an aqueous solution containing an inorganic colloid substance is applied to the surface of the cold rolled steel sheets before the above annealing, and then annealing is performed, during which time the film is fired. and 0.02~o, sy/=
A strain-relieving annealing anti-seize coating is applied to an electromagnetic steel sheet, which is characterized by forming a fired film on the electromagnetic steel sheet, and then temper-rolling it using a rolling oil having anti-corrosion properties with the fired film still attached after annealing. Method.