JPH01186292A - Working method for rolling roll by pulse laser and rolling method thereof - Google Patents

Abstract

PURPOSE:To improve the coating reflexibility and press workability of a rolling roll by controlling a dull working shape by using a pulse oscillator having a specified pulse output of the laser beam. CONSTITUTION:The lamp power source 25 for laser oscillation by a dull working control circuit 30, the motor M1 for work head and the motor M2 for rotating a roll are controlled by using the pulse laser oscillator 10 modulatable in pulse output 1-20mJ/pulse, frequency 1-50kHZ and pulse width 1-10musec respectively. The laser light LB emitted from a laser oscillator 10 is focused on the surface of a roll 40 via bending mirrors 34, 35, 36 and a lens 33 and a rugged type motif is formed on the roll surface in regular order based on the control of the dull working shape. Consequently the steel plate having excellent coating reflexibility and press workability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for dulling a rolling roll using a laser, and a rolling method using the dulled roll.

[Prior Art] The fact that the painted surface of a steel plate used in automobiles and home appliances exhibits a vivid luster (paint clarity) increases its commercial value. Conventionally, as a means to improve the sharpness of paint, emphasis has not been placed solely on improving paints and coating methods.

On the other hand, in order to improve paint adhesion and press workability, automotive steel sheets are temper-rolled (pressure adjusted) using rolls (dull rolls) with minute irregularities on the surface during the manufacturing process. It is given a roughness (roughness) of . In recent years, it has become a problem that when waviness of a certain value or more occurs in the steel plate as a result of imparting roughness during this pressure adjustment process, the sharpness of the coating deteriorates.

Therefore, in order to obtain a steel plate with excellent characteristics in both paint clarity and press workability, both the roughness and waviness imparted to the steel plate in the pressure adjustment process must be within a predetermined range.

Conventionally, shot blasting and electric discharge machining have been used to dull rolls, but both methods have theoretical limits in terms of controllability of the roughness of the roll surface. Therefore, as shown in Japanese Patent Application Laid-Open No. 54-61043, a laser dull processing method using a laser beam with excellent controllability as an energy source for dull processing has attracted attention in recent years.

A method of processing a conventional laser dull roll and a method of manufacturing a steel plate using the same roll are shown in FIGS. 2 to 4, respectively.

In other words, when a pulsed laser beam with a constant peak value and pulse width is focused into a minute spot using a condensing lens and irradiated onto the roll surface, a series of processes of heating, melting, and solidification results in a particle size ranging from several um as shown in Figure 2. A minute motif with protrusions of several tens of micrometers is formed. By scanning the laser beam across the roll surface under these irradiation conditions,
Motifs can be formed regularly.

[Problems to be Solved by the Invention] However, the following problems occur in the above steps.

That is, as shown in FIG.
-a, when the steel plate 50 is rolled in the rolling direction 52, roughness is imparted to the surface 51 of the steel plate 50 as shown in FIG. Because of this mechanism, the transfer rate is significantly reduced due to wear of the convex portions due to rolling.

In particular, in laser dulling, the hardness of the convex portions may be lower than that of rolled material due to the tempering effect on the quenched roll. As a result, the life of the evening roll is shortened, leading to an increase in costs such as roll grinding costs, leading to an increase in manufacturing costs. Therefore, it is necessary to make the convex portion higher.

Currently, as industrial pulsed lasers that can be used for laser dull processing, there are two types of pulsed YAG lasers as shown in Table 1.
There are lasers, but each has its own problems.

Table 1 Types and characteristics of YAG lasers 1) Q-switch pulse ``YAG laser Q-switch pulse provides a pulse output approximately 102 to 103 times larger than continuous oscillation output, and by repeating this Q-switch operation, a maximum of 50kHz can be achieved. Although the pulse width shows some dependence on the pulse frequency, it is generally difficult to control.

In this way, in the case of a Q-switched YAG laser, the pulse width is too narrow at 100 to 500 nsec, and the peak value is as high as 50 kW, resulting in more evaporation phenomena, less convex formation by molten metal, and only one crater ( irradiation with multiple pulses rather than a single pulse is required to form a ring-like structure.

2) Normal pulse YAG laser In the case of a normal pulse YAG laser, the pulse width is 0.
1 ms to 20 m5 is sufficient for the formation of craters, especially convex parts, considering the transfer rate to the steel plate surface, but since the pulse repetition frequency is extremely low (100 Hz), the machining time for the entire roll is longer than the Q-switched YAG laser. 10-2 compared to
It becomes 0 times longer.

Therefore, the necessary characteristics of a pulsed laser that enables the formation of a convex portion as a normal dull shape and high-speed processing are a wide pulse width and a high repetition frequency.

Therefore, the present invention provides a new rolling roll processing method capable of solving the above-mentioned disadvantages of the conventional laser dull steel plate manufacturing method, and a steel plate rolling method using the rolling roll.

[Means for Solving the Problems] The present invention solves the problems of the prior art as described above and manufactures rolls using a laser. In the dulling of rolling rolls using laser beams, the pulse output of the laser beam is
1-20mJ/pulse.

The purpose of this method is to use a pulsed laser oscillator that can be modulated to a frequency of 1 to 50 kHz and a pulse width of 1 to 10 μsec, and to regulate the pressure with a dull roll having an optimally formed dull shape.

Further, the present invention is characterized in that a motif having a regular and constant pattern is formed on the surface of the rolling roll.

Furthermore, the present invention is characterized in that the rolling roll dulled as described above is used for rolling and manufacturing a steel plate having excellent paint clarity and press workability.

[Operation Fig. 5 shows the laser oscillator of the present invention, which solves the problems of the conventional technology and is a high repetition pulse YAG laser, which is characterized by a pulse output of 1 to 20 mJ/pulse, a frequency of 1 ~50k)lx, pulse width 1~IOμs
Pulse oscillation is possible within the ec range.

The basic principle of pulse oscillation itself is similar to the normal pulse method; in the present invention, the YAG lot is excited to near the laser oscillation threshold by the simmer current Is sent from the simmer power supply 23 by the simmer power supply control 24 in advance. Therefore, in the present invention, pulse oscillation can be achieved by superimposing a lower pulse current value than in the conventional normal pulse method. Pulse control 22 and pulse power supply 2
1 sends out a pulse current ip.

Furthermore, since a discharge path is always formed within the lamp and light can be emitted in a low impedance state, the voltage applied to the lamp can also be lowered at the same time. That is, if the pulse output and frequency are considered constant, the average value of the energy applied to the lamp decreases. Therefore, according to the present invention, it is possible to increase the repetition frequency of the pulse current within the limit of human power of the lamp.

Furthermore, in the present invention, the laser oscillation threshold value can be changed by the Q value of the resonator, thereby making it possible to control the excitation state of the entire laser.

FIG. 1 shows an overall diagram of the laser dull roll processing method according to the present invention. The dull processing control circuit 30 controls the lamp power source 25 for laser excavation and the motor M1 for the processing head 31. The roll rotation motor M2 is controlled by the laser peak value, pulse frequency, processing head movement amount, and rotation speed, respectively.

The laser beam LB sent out from the laser oscillator 10 is focused on the surface of the roll 40 via the bending mirrors 34, 35, 36 and the lens 33, and a concave-convex motif is regularly formed on the roll surface based on the above control. be done.

[Example] Here, the laser dulling system shown in Fig. 1 is used to dull the roll surface, and the rolling example shown in Fig. 3 performed using the dulled roll is explained by giving a specific example. do. Dulling is a cold-rolled steel plate manufacturing process in which a steel plate is rolled using a rolling roll 40 that has minute irregularities 42 on its surface as shown in Fig. 4, resulting in depressions 53 on the steel plate surface 51 and roughness. (roughness) can be processed.

Table 2 shows the laser irradiation conditions and processing results in Examples. In the table, ■ is a Q-switched laser, and ■ and ■ are different types of laser oscillators from the laser oscillator of the present invention, but the processing conditions other than the laser pulse irradiation time (pulse width) Pw are almost the same.

Comparing the machining results, the height h of the ring-shaped protrusion 42 is higher in case ■ than in case ■. Furthermore, in case (2), the height h of the protrusion 42 becomes even larger than in case (2), perhaps because the pulse width Pw is made wider than in case (2). The following things were found from the above processing results.

Table 2 Processing Results of Examples According to the Present Invention In the laser dull processing according to the present invention, it is possible to control the shape of the melted and resolidified material on the roll surface, and the roughness of the finally obtained rolled steel plate can be controlled. Therefore, the laser dull processing apparatus using the pulsed YAG laser according to the present invention can achieve a pulse irradiation time suitable for melt processing, and at the same time,
By controlling the pulse width, the roughness controllability and wear resistance of the steel plate were significantly improved compared to equipment using a conventional Q-switched YAG laser.

[Effect of the invention] By the roll processing method of the present invention, high repetition pulse YA
Using a G laser, it has become possible to perform melt processing faster than before. Moreover, when a steel plate is rolled using the roll obtained by this processing method, the roughness controllability and wear resistance of the steel plate are greatly improved, and the steel plate has excellent paint clarity and press workability. or can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a dulling system according to the present invention, FIG. 2 is a diagram showing a motif shape formed on the roll surface after laser irradiation, and FIG. 3 is a diagram showing the state of rolling of a steel plate by a dulling roll. Figure 4 is a diagram showing the roughening process (recesses) on the surface of a steel plate by rolling the steel plate with the barrel processing roll of Figure 3, and Figure 5 is the structure of the pulsed YAG laser of the present invention and the excitation lamp power supply for the oscillator. FIG. 10... Laser oscillator, 11... Elliptical condenser, 12
... Resonator rear mirror, 13 ... Resonator output mirror, 17 ... YAG rod, 20 ... Flash lamp, 25 ... Lamp power supply, 30 ... Dull processing control circuit, 31 ... Processing head, 32...Processing gas, 33
...Condensing lens, 34-36...Bending mirror, 40.40-a...Roll, 41...Roll surface, 42...Ring-shaped protrusion, 50...Steel plate, 51
...Steel plate surface, 52...Steel plate threading direction, D...Ring diameter, Ml...Machining head motor, M2...Roll rotation motor, h...Protrusion height, d. ...Crater depth, L B-...Laser beam, Pp...Peak value, Pw...Pulse width, f...Pulse frequency.

Claims (3)

[Claims] 1. In dull processing of rolling rolls using a pulsed laser, the shape of the dull processing is controlled using a pulsed laser oscillator that can modulate the pulse output of the laser beam to 1 to 20 mJ/pulse, frequency of 1 to 50 kHz, and pulse width of 1 to 10 μsec. A rolling roll processing method characterized by: 2. 2. The method for processing a mill roll according to claim 1, wherein a motif having a regularly fixed pattern is formed on the surface of the mill roll. 3. 3. A rolling method using a rolling roll according to claim 1, wherein the dulled rolling roll is used to produce a steel plate having excellent coating clarity and press workability.