JPH02268989A - Dull working method for surface of roll - Google Patents

Abstract

PURPOSE:To automatize the focusing and to execute stable dull working by measuring strength and an area of plasma generated at the time of working by a photodetector, and controlling a distance from the surface of a roll of a focus lens so that its value becomes optimum. CONSTITUTION:In order to set a laser output before working and to focus the laser on the surface of a roll 40, a moving adjustment of a working head 20 in a prescribed section is executed by a movement control part 30, a pulse motor 31 and a slide part 32. Simultaneously, the light emission intensity and an area of plasma PL photographed by a photodetecting part 50 are converted to numerical values by an image analyzing mechanism 52, and thereafter, stored in a memory provided in the image analyzing mechanism 52. After the measurement is ended, the working head 20 is moved to a position in which its value becomes maximum, and in its state, working is executed again, a shape of a crater is observed, and if necessary, a laser output is set again, and by the same process, an optimum position of the working head 20 is analyzed and it is moved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for dulling the surface of a roll for rolling a steel plate or the like using a laser.

(Conventional technology) Steel plates used for the exterior panels of automobiles and home appliances must have high paint clarity (the degree to which the painted surface exhibits a bright gloss), and this is an important factor in determining product value. It has become.

Traditionally, attention has been paid exclusively to paints and coating methods as a means of improving paint clarity, but in recent years, surface roughness and waviness, which are characteristics of the base steel sheet, have begun to affect paint clarity. This is becoming clear.

In general, cold-rolled steel sheets are subjected to temper rolling during the manufacturing process using rolls having fine irregularities on the surface (hereinafter referred to as dull rolls), and the irregularities of the rolls are transferred to impart roughness to the surface of the steel sheet. In order to ensure the press workability and paint clarity required for Il plates, the surface of the steel plate must have a roughness above a certain value, but as the roughness value increases, the waviness of the steel plate increases. However, in order to manufacture a steel plate with excellent both paint clarity and press workability, a dull roll with a high roughness value and low waviness is manufactured, and the roll It is necessary to temper-roll the steel plate.

One of the ways to achieve the above-mentioned high roughness and low waviness is to
There is a laser dull processing method that processes rolls using a highly controllable laser as an energy source.

The laser dull processing method and its apparatus are disclosed in, for example, Japanese Patent Publication No. 5B-25557 and Japanese Patent Publication No. 60-2156. In particular, the apparatus disclosed in Japanese Patent Publication No. 60-2156 uses a pulse laser using a YAG laser or the like. It has been described that the surface of a rotating roll is dulled using the following method.

(Problem to be solved by the invention) In laser dull processing, in order to form a crater with minute irregularities on the surface of a roll, the required laser output is set primarily, and the laser beam is applied to the processed part of the roll surface following the roll shape. After adjusting the position of the lens to focus (hereinafter referred to as focusing), it is necessary to irradiate the laser beam and adjust the laser output so that the crater shape formed on the roll surface is optimal.

In the conventional method, the laser output is adjusted to optimize the crater shape, but at this time, the divergence angle of the laser beam, which affects the focusing characteristics, changes depending on the laser output, so each time the laser output is adjusted, Focusing is required. In other words ■
Perform the output setting, ■focusing, ■laser irradiation, and ■crater observation in sequence.If the shape of the crater observation in (■) is not appropriate, return to the output setting in (■) and proceed with the steps from (■) to ().
It was a pain to have to repeat the procedure.

In order to keep the divergence angle of the laser beam constant even when the laser output is changed, it is necessary to control the oscillation system inside the laser oscillator, and the technology is advanced and applying it to general processing lasers is difficult from both technical and cost perspectives. It is difficult. There was a problem.

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and aims to provide a method for dulling a roll surface that does not require focusing even if the divergence angle of the laser beam changes by changing the laser output. That is.

(Means for Solving the Problems) The essential feature of the present invention is the processing method in which the surface of the roll is irradiated with a pulsed laser beam in a scanning manner to form countless fine irregularities on the surface of the roll. (1) Measure the intensity, area (generation area), or both of the plasma generated during processing using a light receiving element such as an image tube, photo multiplier, or pin photodiode, and optimize the value. Controlling the distance of the focusing lens from the roll surface (first invention).

(2) In (1) above, from 480% m to 620 m
To clarify changes in plasma generation intensity and area by using a wavelength selection filter (second invention).

(3) Furthermore, in the above (1) or (2), Ar.

To stably generate plasma by spraying an inert gas such as He to a laser irradiation point, and to stably and accurately measure the intensity and area (generation area) of the generated plasma (third invention).

A method for dulling a roll surface is characterized in that focusing during dulling is automatically performed in each of these invented methods.

(Operation) The device to which the present invention is applied is mainly composed of five mechanisms.

(1) Pulse laser oscillation system.

(2) Processing head mechanism with a built-in lens to focus the laser beam.

(3) A drive mechanism that moves the position of the processing head back and forth.

(4) Roll to be processed.

(5) Light receiving section and its analysis mechanism.

FIG. 1 is a schematic diagram of these, and the present invention will be explained in detail below using FIG. 1.

Laser beam 12 emitted from pulsed laser oscillator 10
is focused by a lens 21 fixed within the processing head 20 and irradiated onto the surface of the roll 40 to be processed. When the surface of the roll 40 is irradiated near the focal point, the metal on the surface of the roll melts and evaporates, generating plasma PL accompanied by light emission. When the laser beam 12 is focused on the roll surface, the emission intensity and area of the plasma PL are maximized.

Before main processing, the laser output is set, and in order to focus on the surface of the roll 40, the movement control unit 30 adjusts the movement of the processing head 20 for a certain period so that the focal length of the lens 21 is at least ±2 rm. After converting the emission intensity and area of the plasma PL photographed by the light receiving unit 50 with or without the wavelength selection filter 51 into numerical values using the image analyzer $152 while using the pulse motor 31 and the slide unit 32. , is stored in the memory of the image analyzer tJI52, and after the measurement is completed, move the processing head 20 to the position where the value is maximum, perform processing again in that state, observe the shape of the crater, and use the laser if necessary. The output is reset and the optimum position of the processing head 20 is analyzed and moved through the same process.

In addition, in the above measurement, the wavelength selection filter 51 is used as necessary, but compared to the case where it is not used, when the wavelength selection filter 51 that transmits light from 480 nm to 620 nm is used, the emission intensity of the plasma is Changes in area can be separated more clearly. As the wavelength selection filter 51, it is preferable to use a bandpass filter that transmits all light from 480 nm to 620 nm or an interference filter that transmits only light before and after a specific wavelength.

In the present invention, laser irradiation may be performed by spraying an inert gas such as Ar gas onto the laser irradiation point.This is because the ionization voltage required to turn nitrogen into plasma in the atmosphere is 24.30
Compared to V (N! -N+N and N-N°+6-), the ionization voltage required to turn argon into plasma is 15.76
Plasma is generated stably at a low eV (A r-eA r" 10e-), and plasma measurements can be made stably and with high accuracy.

(Example) An example in which the present invention is implemented using the configuration shown in FIG. 1 will be described.

The size of the work roll 40 is 600 m in diameter and 20 m in length.
This is 00kaku. The laser oscillator 10 is a Q-switched YAG laser with an average output of 100 W, and the condenser lens 21 has a focal length of 5.
0III11, the interference filter 51 uses the 500 nm band. When focusing, move the processing head 20 toward the roll 40 side. As OLI approached one by one, roll 4
FIG. 2 shows changes in the emission intensity of the plasma generated on the zero surface, and FIG. 3 shows changes in the area of the plasma. The gap value indicates the distance between the surface of the roll 40 and the processing blade 20. and both show the changes when using the interference filter 51 that transmits the 500 nm band and when not using the interference filter 51, and the values are calculated by image processing l5lt.
This is a value obtained by correcting the measured values digitized in l152 by setting the maximum value to 1.

In either case, the distance between the roll surface and the processing head 20 is 0.
．． The measured value is maximum at the time of 5 points, indicating that the processed part of the roll surface is in focus. In this case, if an interference filter is used, changes in measured values can be obtained more clearly, so the position where the plasma generation intensity or area is maximum can be easily determined.

The interference filter used is from 480 nm to 62 nm.
High-sensitivity measurement is possible with any material that has transmission characteristics within 0 nm. Figure 4 shows the surface of the roll 40 and the processing head 2.
The plasma emission intensity is measured using various interference filters 51 while keeping the interval distance of 0 constant, and is corrected by setting the maximum value to 1.

From Figure 4, when using an interference filter with transmission characteristics between 480 nm and 620 nm, the relative sensitivity is 0.5.
The above measurements are possible.

(Effects of the Invention) Since the present invention is configured as described above, there is no need to perform focusing every time the laser output is set, and focusing is automated. This eliminates individual differences among operators and enables stable dull processing. Further, there is an effect that there is no risk of an accident due to the operator getting close to the laser beam.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the device to which the present invention is applied, Figures 2 and 3
The figure is a graph showing changes in plasma emission intensity characteristics and area characteristics measured when changing the distance between the processing head and the roll, and Figure 4 is a graph showing the transmission characteristics of plasma emission intensity at each wavelength. . 10: Laser oscillator, 12: Laser beam, 21: Lens, 30: Movement control J system 32: Movement mechanism, 41: Roll axis, 5I; Filter 11: Laser control system, 20: Processing head, PL: Plasma, 31: Pulsmoke, 40: Roll, 50: Light receiving system, 51i# Image processing analysis system. Sub-Agent Patent Attorney 1) Hiroshi Mura Disciple 1 Ki'γ Tebu (#1)

Claims (3)

[Claims] (1) In a dulling method in which countless minute craters are formed on the surface of a rolling roll using a laser beam,
A roll surface control method that measures the intensity of plasma generated during processing, the area of the plasma generation area, or both, and controls the distance of the condenser lens from the roll surface so that the values are optimized. Dull processing method. (2) The method for dulling a roll surface according to claim 1, characterized in that a wavelength selection filter from 480 nm to 620 nm is used to clarify changes in the plasma generation intensity and the surface of the generation area. (3) Inert gas such as Ar is sprayed onto the laser irradiation point to stably generate plasma, and the measurement of the intensity of the generated plasma and the area of the generation area is made stable and highly accurate. Or the method for dulling the roll surface according to 2.