JP2965419B2 - Dimple processing equipment for cooling drum for slab casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for processing a cooling drum for casting slabs, and more particularly, to a method for irradiating a laser beam to a cooling drum surface such as a single drum system, a twin drum system, and a drum-belt system in continuous casting. The present invention relates to a processing device for forming dimples.

[0002]

2. Description of the Related Art In the field of continuous casting, there is a strong demand for the development of a technique for directly producing thin cast slabs having a thickness close to the final shape of a product (hereinafter referred to as thin cast slabs) from molten steel. When casting a thin cast slab, compared with casting a thick cast slab, molten steel is cooled considerably more rapidly by a cooling drum, so that the cast slab undergoes a change in wall thickness or surface cracks. Therefore, it is necessary to make a cooling drum that does not cause these defects.

[0003] For example, Japanese Patent Application Laid-Open No. 60-184449 proposes that an "air pocket" is formed by providing uniform unevenness on the entire peripheral surface of a cooling drum and an "air layer" is formed on the peripheral surface of the cooling drum. Have been. This is because the thickness of the "solidified shell" formed is made uniform in the plate width direction by reducing the heat removal capacity of the cooling drum by the "air pool" and slowly cooling the molten steel, thereby causing wall thickness fluctuation and surface cracking. This enables casting of thin cast slabs without slabs.

[0004]

However, when casting is performed using a cooling drum provided with irregularities, traces of irregularities (transfer traces) are transferred to the slab surface. Since the unevenness of the transfer mark is smoothed by subsequent rolling, there is no problem, but if coarse particles exist in a part of the transfer mark, it remains as a bruise,
The value of the cast product is lost.

Further, when molten steel is cast using a cooling drum provided with irregularities, a "surface wave" is generated in a "puddle" of the molten steel, and horizontal wrinkles are formed on the surface of the cast slab to be cast, and gloss is generated. It causes defects such as unevenness and coarse crystal structure. For this reason, great care must be taken not to generate "surface waves" during the casting operation.

[0006] For example, the cause of the generation of "bruise" is caused by a part that is "slowly cooled" by the "air pool" (a part where coarse particles are formed) and a part that is directly contacted with the cooling drum and is "rapidly cooled" (a minute part). This is because there is a difference in the crystal grain size of the molten steel solidified in the molten steel (grain-forming portion) and the difference in the grain size appears as “bruise” due to the difference in light reflectance. This is because irregularities formed on the peripheral surface of the cooling drum are large with respect to the cooling rate distribution of the molten steel.

[0007] On the other hand, the cause of the generation of "surface waves" is that when a "solidified shell" is formed, there is a difference between a "rapidly cooled" portion and a "slowly cooled" portion in the traveling direction of molten steel at the cooling drum interface. This is because the boundary is formed almost continuously in a local area. This boundary is, for example, irregularities are provided regularly at intervals on the peripheral surface of the cooling drum, or the surface tension to be formed by the irregularities is not obtained, and as a result there is a “rapid cooling” portion Thereby, the "quenching" portion is configured to be formed in a chain.

It can be seen that the problems of "bruise" and "surface wave" are caused by irregularities formed on the cooling drum. It can be seen that in order to solve such a problem, it is necessary to consider the size, shape, and arrangement of the unevenness (or dimple) to be formed.

Conventionally, the method used to obtain the above cooling drum is mainly wet etching. Etching has achieved quite fine processing in the field of microelectronics and the like. However, in the processing of this cooling drum, the processing size is limited because the diameter of the dimple to be processed is reduced and the depth thereof is also required. In fact,
The dimple depth required to assure the surface tension to be formed by the above-mentioned uneven portion is about 70 μm, and the dimple diameter dimension is at least about 300 μm in order to obtain this depth dimension.
μm. In other words, if the dimple diameter is set to 300 μm or less, the dimple depth cannot be obtained and the surface tension cannot be guaranteed.

In addition, in etching, it is difficult to flexibly change each dimension relating to the size, shape and arrangement of dimples. In addition, there is a concern about environmental issues that have recently been taken up, including the peripheral equipment related to chemical treatment used for the etching.

In addition, shot blasting, electric discharge machining, machining, and the like are also used for dimple machining. But,
As with etching, shot blast has problems such as limitations on processing dimensions, dimensional control, processing accuracy, and the like. Although micromachining is possible in electrical discharge machining and machining, the number of dimples machined for the cooling drum is very large,
It is industrially inappropriate or impossible in terms of time, including electrode replacement.

An object of the present invention is to provide a processing apparatus for forming dimples by irradiating a “laser beam” to the peripheral surface of a cooling drum. In particular, it is an object of the present invention to provide a multi-processing apparatus capable of performing a plurality of dimple processing at a time by using a plurality of laser oscillators, thereby shortening the processing time.

It is a further object of the present invention to provide a laser processing device using a plurality of laser devices, wherein the laser light oscillated from each laser device is focused on a processing surface by using a focusing lens. Is to solve the problem that it is difficult for each laser beam to properly form a focus because each has a unique divergence angle.

[0014]

FIG. 1 shows an embodiment of an apparatus for achieving the above object. A dimple processing apparatus according to the present invention is a rotating cooling drum for casting slabs.
(5) a mechanism for irradiating the laser beam with the laser beam ;
A mechanism for relatively moving the cooling system in the axial direction of the cooling drum.
A dimple processing apparatus for forming dimples on the peripheral surface of the cooling drum by using the laser beam, wherein a plurality of laser means (1) for generating laser light; and each of the generated laser lights. with focus before Symbol Rezabi beam by adjusting the divergence angle of the surface of the cooling drum, the cooling de
A plurality of divergence angle adjusting means for vibrating in the axial direction of the ram (2)
When an optical path means for focusing illuminated the adjusted the respective laser beams into the cooling drum surface (3), said plurality of laser hand
Processing control means for controlling the excitation order and excitation interval of the stages
(4) .

[0015]

By using a laser beam, the diameter of the laser beam can be reduced to about three times the wavelength, so that it is possible to process the cooling drum peripheral surface with fine dimensions that cannot be achieved by a conventional processing apparatus. Become. Further, since the laser processing is performed, its electrical control is possible, and flexible dimension setting for dimples to be formed becomes possible. In addition, it does not cause problems related to the use of chemicals.

Since the divergence angle of each laser beam is individually adjusted by the divergence angle control means, the focal point of each laser beam is appropriately formed on the processing surface. Thus, a plurality of laser units having different characteristics such as output can be combined.

Further, since multiple processing can be performed by a plurality of laser devices, the processing time can be reduced, and other laser control means and optical path means can be shared.

[0018]

FIG. 2 shows an embodiment according to the present invention. The dimple processing apparatus 20 includes four laser oscillators 21-24.
A beam expander 29-32 for adjusting the divergence angle of the laser light 25-28 oscillated therefrom; and a laser beam 33-3 adjusted by each beam expander.
6, an optical system 47 including a galvanometer mirror 37-42 (hereinafter, referred to as a mirror), a triangular mirror 43-45, and a condenser lens 46, and a processing controller 48 for controlling the oscillation timing of laser light. It is provided with.

The cooling drum 50 rotates at a constant speed ω about its rotation shaft 51, and the rotation speed ω is maintained by a rotation controller 52.

The processing device 20 is suspended by a sweeping device 53 that moves at a predetermined constant speed v while maintaining a constant distance a from the surface of the cooling drum 50 rotating at a predetermined speed in the rotation axis direction. Is maintained by the sweep controller 54, so that each laser beam consequently spirally scans the peripheral surface of the cooling drum 50. Of course, the arrangement relationship between the processing apparatus 20 and the cooling drum 50 may be such that the cooling drum 50 itself moves in the direction of its rotation axis while rotating.

Each of the laser oscillators 21-24 of the present processing apparatus uses four YAG lasers.
For example, a continuous wave gas laser such as a carbon dioxide gas laser,
Alternatively, a pulse oscillation type solid laser such as a ruby laser may be used, or a combination thereof may be used. The processing controller 48 outputs the laser light to each of the laser oscillators 21.
The pulse is generated by simultaneously or sequentially controlling the Q switches 55-58 in -24.

The beam expander 29-3 according to the present invention
2, when a plurality of laser devices are used as described above, when the laser light is focused by one condensing lens 46 in common,
This is provided to solve the problem that the laser light emitted from each laser device has a unique divergence angle, so that it is not possible to appropriately form a focus. The divergence angles of the laser beams from the laser oscillators 21-24 are individually adjusted by the beam expanders 29-32 so as to appropriately form a focal point on the processing surface, and the laser beams become laser beams. Thus, stable light-collecting conditions can be obtained even when one light-collecting lens 46 is shared.

Each of the mirrors 37-42 and the condenser lens 46 of the optical system is provided with a mechanical or electrical drive (not shown) for moving the angular position and the focal length.

The mirror 37 changes the optical path of the laser beam 33 according to the reflection angle φ _1, and guides the laser beam to the mirror 41 via the triangular mirror 43. The mirror 41 is shared with the laser beam 34 guided similarly to the mirror 37, and displaces the optical path of each of the laser beams 33 and 34 so as to make the laser beams enter the condenser lens 46 at the incident angles α ₁ and α ₂ , respectively. Since the angle position of the mirror 41 can be changed by the vibration period f ₅ and the vibration angle φ ₅ , the reflection angles of the laser beams 33 and 34 can be changed, and the axes of the laser beams can be displaced according to the vibration angle φ _5. it can. Thereby, the incident angles α ₁ and α _{2 at} which the respective laser beams enter the condenser lens 46 are changed, and the position at which the laser beams are focused on the cooling drum surface can be changed. Similarly, one of the laser beams 35,
Since the laser beam 36 is also incident on the condenser lens 46 at the incident angles α ₃ and α ₄ , a plurality of focusing positions are individually defined for each laser beam on the cooling drum.

Further, one stage provided for each laser beam
The eye mirror 37-40 also has a vibration period f _1-4And vibration angle φ
_1-4Each laser beam
Is the vibration angle φ_1-4According to the above, focusing on each focusing position
The focusing position can be further changed in the direction of the rotation axis of the drum.
Wear.

The processing controller 48 supplies the laser excitation signals 59-63 to the Q switches 55-58 of each laser oscillator simultaneously or sequentially at different time intervals. For example, the excitation timing signal having a constant period is modulated to give a predetermined time difference, so that the laser oscillation timing varies. Thereby, the interval between the irradiation positions of the laser beam varies in the rotation direction of the cooling drum, so that the positions of the dimples formed are dispersed in the rotation direction of the cooling drum.
As described above, since the positions of the dimples formed on the cooling drum can be dispersed within a predetermined range in the rotation direction and the rotation axis direction of the cooling drum, a plurality of dimples can be dispersedly formed at the same time.

With the dimple processing apparatus of the present embodiment, four YAG lasers having a wavelength of 1.06 μm are used to set 500 pulses / sec, pulse width 0.1 msec, 100 mJ / pulse, and a double beam expander. The experiment was performed using a condenser lens having a focal length of 50 mm. As a result, dimples having a dimple diameter of 150 μm, a dimple depth of 100 μm, and a distance between the dimple centers of 80 μm to 140 μm were formed on the peripheral surface of the cooling drum.

The above embodiment is an example in which a plurality of dimples can be processed by dispersing and arranging a plurality of dimples at the same time using a plurality of laser oscillators. Since it is possible to combine multiple laser devices with different characteristics such as
Various dimples having different dimple depths and dimple diameters can be formed.

In addition, in the processing control of the processing controller 48, the timing of the laser excitation signal given to the laser oscillators 21-24 and the timing of the angular displacement of each of the mirrors 37-41 are synchronized, so that Dimple processing can be performed under complicated conditions combining requirements. This is made possible by such a device using a laser.

[0030]

According to the present invention, there is provided a processing apparatus for irradiating a "laser beam" to form dimples on a cooling drum for casting slabs. In particular, there has been provided a multi-processing apparatus capable of performing a plurality of dimple processing at a time using a plurality of laser oscillators. Further, in processing using a plurality of laser devices, by adjusting the divergence angle of each laser, even if a plurality of laser beams form an optical path by sharing a focusing lens, the focus can be appropriately adjusted on the processing surface. Configuration was achieved.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a processing apparatus according to the present invention.

FIG. 2 is a view showing one embodiment of a processing apparatus according to the present invention.

[Explanation of symbols]

20 dimple processing apparatus 21, 22, 23, 24 laser oscillator 25, 26, 27, 28 laser light 29, 30, 31, 32 beam expander 33, 34, 35, 36 laser beam 37, 38, 39, 40, 41, 42 Galvano mirror 43, 44, 45 Triangular mirror 46 Condensing lens 48 Processing controller 50 Cooling drum 52 Cooling drum rotation controller 54 Sweep controller 55, 56, 57 , 58 ... Q switch

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Atsushi Sugihashi 5-10-1 Fuchinobe, Sagamihara City, Kanagawa Prefecture Nippon Steel Corporation Electronics Research Laboratory (56) References JP-A-60-184449 (JP, A) JP-A-63-224886 (JP, A) JP-A-63-207485 (JP, A) JP-A-62-124085 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23K 26 / 00-26/06

Claims (1)

(57) [Claims] A cooling drum for casting a rotating slab.
A mechanism for irradiating the laser beam to the
Has a mechanism to relatively move in the axial direction of the cooling drum,
A dimple processing apparatus for forming dimples on the peripheral surface of the cooling drum by using the laser beam, wherein a plurality of laser means (1) for generating laser light, and a divergence angle of each generated laser light are adjusted. with focus of the Rezabi beam on the surface of the cooling drum, of the cooling drum
A plurality of divergent angle adjustment means for vibrating in the axial direction (2), the optical path means for focusing radiation with the adjusted respective laser beams to the cooling drum surface (3), excitation of said plurality of laser means
A dimple processing apparatus for a cooling drum for casting slabs, comprising: a processing control means (4) for controlling a starting order and an excitation interval .