JPH0374604B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of processing a ceramic member, and more particularly, to a fixing plate for a sliding nozzle for discharging molten metal, which is made of a ceramic member impregnated with tar and is attached to the bottom of a ladle or tundish when casting molten metal. Alternatively, the present invention relates to a method of forming a passage for passing gas through a sliding plate. Conventionally, when casting molten steel using the continuous casting method, a molten metal discharge device consisting of a fixed plate and a sliding plate is attached to the nozzle at the bottom of the ladle or tundish containing the molten steel, and the sliding plate is slid against the fixed plate. By doing so, a passage hole for molten steel is opened and the flow rate of molten steel is adjusted. In the above-mentioned molten metal discharge device, the molten steel passage hole allows the molten steel to solidify, Al, Ti, Ca, Cr,
In order to prevent blockage due to adhesion of metal oxides such as Ni, Mn, and Si, small holes are provided in the fixed plate or sliding plate and an inert gas such as Ar is supplied to the holes through which molten steel passes. is being carried out. The inert gas is supplied, for example, by providing a gas supply body with a plurality of small holes with a circular cross section of 0.1 to 1.0 mm in diameter or a gas supply body with a plurality of slits with a rectangular cross section at a predetermined position on the plate. It is. When forming small holes or slits in the plate, hard paper or vinyl wire is buried in a predetermined position in the clay during the molding of the plate, and the hard paper or vinyl wire disappears during the firing process to form the small holes. Or make a slit,
After firing, it was drilled to create small holes or slits. However, when forming small holes or slits using hard paper or vinyl wire, there is a risk that the small holes or slits may not completely penetrate the plate, and the diameter of each hole may become uneven, causing uneven gas supply. There was a risk that the gas supply would be uneven due to non-uniform hole diameters, and that the work would be time-consuming. Further, when processing using a drill, it is extremely difficult to process thick materials, and the work is time-consuming, and there is a risk that the processed plate will be expensive. The present invention has been made in view of the above circumstances, and its object is to provide a gas supply body fitted to a ceramic plate, for example, a fixed plate of a sliding nozzle for discharging molten metal, or a fixed plate. Another object of the present invention is to provide a method for accurately forming holes as passages for passing gas in a sliding plate, such as small holes having a circular cross section or slits having a rectangular cross section. According to the present invention, the object is to provide a method for processing a ceramic member in which a passage for passing gas is formed in the ceramic member by emitting a laser beam to the ceramic member, the method comprising: preparing a ceramic member; immersing a ceramic member in a bath containing either tar or pitch in a vacuum and then heating the ceramic member to impregnate the ceramic member with either the tar or pitch; and a means for emitting laser light. This is achieved by a method of processing a ceramic member, which includes the step of emitting a laser beam to a ceramic member impregnated with either tar or pitch to form a passage for gas passage. In the method of processing a ceramic member of the present invention, the ceramic member is immersed in a bath containing either tar or pitch in a vacuum before being irradiated with laser light, and then heated to form either tar or pitch. Since it is impregnated into the ceramic member, it is possible to prevent the reflection of the laser beam emitted to the ceramic member, and the heat can be easily absorbed into the processing part, so that the processing of the ceramic member can be easily performed. Preferably, the ceramic member comprises a sliding plate or a fixed plate of a molten metal discharge sliding nozzle. Preferably, the step of forming a passageway for the passage of gas includes focusing laser light emitted onto the ceramic member. Preferably, the step of forming a passageway for the passage of gas includes deflecting laser light emitted onto the ceramic member. Preferably, the step of forming a passage for passing the gas includes blowing a gas onto a portion of the ceramic member irradiated with the laser beam to remove the melted material of the ceramic member irradiated with the laser beam. Contains stages. Preferably, the step of forming passages for passing gas comprises stopping emission of laser light by the means for emitting laser light in order to form a plurality of passages for passing gas through one ceramic member. and displacing the ceramic member and emitting laser light each time the ceramic member is displaced;
Alternatively, the step of forming passages for passing gas may include keeping the ceramic member stationary and displacing the means for emitting laser light in order to form a plurality of passages for passing gas through one ceramic member. , including the step of emitting laser light each time the means for emitting laser light is displaced. According to a specific example of the method for processing a ceramic member of the present invention, a passage for passing gas consisting of a small hole or narrow slit with a hole diameter of, for example, about 0.2 to 1.0 mm can be quickly and uniformly formed in the ceramic member. . Holes in a ceramic member are formed by removing a portion of the ceramic member that has been melted by laser beam radiation, so the processed surface, that is, the inner surface of the hole and the surrounding area of the hole surface, are in a molten state, so there is no possibility of melting. Corrosion resistance due to contact with other materials is improved compared to conventional products. Gas may be blown onto the molten part in order to remove the molten part or cause the melt to scatter, but if the laser radiation can automatically cause the melt to scatter, the gas may not be blown. Note that the center of the gas flow blown onto the melted portion may be shifted from the center of the emitted laser beam, or the gas may be warmed. Ar, _N2 as gas
It may be an inert gas such as or another gas. In some cases, a gas such as oxygen may be used. According to the present invention, the ceramic member processed as described above is impregnated with either tar or pitch before irradiating the laser beam. The volatile components in the tar or pitch that are volatilized at the temperature when the molten metal is discharged protect the surface of the ceramic component, and the residual components that remain in the pores of the ceramic component after the volatile components are volatilized protect the surface of the ceramic component. This prevents intrusion into the pores of the ceramic component, and the ceramic component impregnated with tar or pitch improves the durability of the processed gas supply body or sliding plate. Furthermore, by impregnating with tar or pitch, the temperature of the ceramic member increases, and heat is absorbed into the processing area to prevent reflection of laser light, making processing easier. First, a CO ₂ laser device used in a specific example of the step of forming a passage for passing gas in the processing method of the present invention will be explained with reference to FIG. As the laser light source, other laser light sources such as a YAG laser may be used instead of the CO ₂ laser as long as the output is sufficiently large. Laser light 2 emitted from the laser light source
The CO ₂ laser device 1 is equipped with a lens 2 to focus the laser beam 5 onto a focal point 3 . Incidentally, if the hardness of the laser beam is sufficiently strong, a slit or the like may be provided in the path of the laser beam in order to narrow down the width of the laser beam. The nozzle 5 has a lens 2, a base portion 27 having an auxiliary gas flow hole 6, a small diameter portion 26 for guiding the auxiliary gas, and an exit opening 24 for the focused laser beam and the auxiliary gas. The focal point 3 is located inside a workpiece 4 as a ceramic member, for example, a disc-shaped gas supply body fitted into a fixed plate of a sliding nozzle for discharging molten metal, and gas is supplied to the workpiece 4. The device 1 is configured to emit focused laser light 23 from the outer surface 21 of the workpiece 4 to create a small hole 22 as a passageway. If the distance from the outer surface 21 of the workpiece 4 to the focal point 3 is the focal depth H, and the hole diameter of the small hole 22 is h, then the larger the focal depth H is, the larger the hole diameter h becomes, and the laser density becomes smaller. It takes time to make holes. In order to form the small hole 22 as a passage for gas to pass through, the focal depth H is preferably 0 to 10 mm. The device 1 may be arranged to change the depth of focus H each time a laser pulse is emitted. A specific example of a method of processing a ceramic member using the laser device 1 described above will be explained. The prepared workpiece 4, which is a ceramic part in which channels are to be formed for the passage of gas, is impregnated with tars (either tar or pitch) before being irradiated with laser light. This impregnation operation is performed by vacuum impregnation and heating. If desired, the cycle of vacuum impregnation and heating may be repeated two or more times, i.e., immersing the ceramic part in a bath containing tars in vacuum and heating the ceramic part once removed from the bath. This may be done by repeating the above steps. As the impregnating material, liquid resins other than tars may be used. The amount of tar impregnated is preferably 15% by weight or less. This is because if the content exceeds 15% by weight, the heat conductivity of the ceramic material increases, causing heat to be dispersed and not concentrated in the processing area, making it impossible to process the desired minute holes or slits. It is. Processed product 4 impregnated with tar is laser device 1
are placed in close proximity to each other to form a passageway through which the laser beam is emitted and the gas passes. The laser beam directed onto the workpiece 4 is focused by the lens 2 to a focal point 3. By flowing the auxiliary gas into the auxiliary gas flow hole 6 provided in the base 27 of the nozzle 5, the lens 2 can be protected and the melted material of the workpiece 4 can be scattered.
N ₂ , O ₂ , air, etc. are used as auxiliary gases, but N ₂ and air are preferred, with a flow rate of 30 to 150/
Used in min. If the flow rate is less than 30/min, the molten material will not scatter and the porosity ratio, that is, the ratio of the number of times the laser beam is emitted to open the holes to the number of holes opened, will be poor, and if the flow rate exceeds 150/min, the melt will scatter. The disadvantage is that the pore size becomes large because the pore size becomes too intense. The auxiliary gas may be introduced continuously or may be introduced intermittently every time the laser beam is emitted. Further, the laser beam used in the specific example of the processing method of the present invention has an average output of 200 W or more, and if it is less than this, the time required for processing becomes longer, which is not preferable.
The maximum output is preferably 1Kw or more, and the frequency and pulse width are preferably 50 to 150 Hz and 3 to 10 ms. Outside this range, the temperature of the machined surface will not be appropriate and it will take a long time to open the hole. The open area ratio also deteriorates. It is preferable to use a lens 2 with a focal length of 5 to 15 inches; if the focal length is shorter than 5 inches, the aperture ratio decreases due to the defocus, and it becomes difficult to control the aperture diameter. If the diameter exceeds 15 inches, the disadvantage is that the density of the laser beam is low and it takes a long time to open the hole. The closer the distance between the outer surface 21 of the workpiece 4 and the outlet 24 of the nozzle 5 during processing, the better.
If it is shorter than 2 mm, the lens will be contaminated with melted particles and the nozzle 5 will be clogged, so 2 mm to 15 mm is preferable. Moreover, if it exceeds 15 mm, scattering of the melt will be reduced and the porosity will be poor. The mode of the laser beam 25 includes single mode and multimode, and single mode is preferable for opening small holes. By keeping the laser device 1 stationary and rotating the workpiece 4 about the center of the disc-shaped workpiece 4, a plurality of small holes 22 are machined concentrically in the workpiece 4. Further, by displacing the workpiece 4 in the height direction of the workpiece 4, a plurality of small holes 22 are formed in the height direction of the workpiece 4. By combining rotation and displacement in the height direction, any number of small holes 22 can be machined from any part of the outer surface 21 of the workpiece 4. Instead of rotating or displacing the workpiece 4 in the height direction, the workpiece 4 is kept stationary and the laser device 1 is operated so that the focused laser beam 23 is emitted to the part where the small hole 22 is to be machined. It may be displaced. The cross section of the small hole 22 is preferably circular with a hole diameter of 0.2 to 1 mm as a passage for passing gas. This cross-sectional shape may be oval or other shape. Also, instead of a small hole, a slit having a rectangular cross section may be machined. Instead of the workpiece 4 being a disc-shaped gas supply fitted to the fixed plate of the sliding nozzle for discharging molten metal, it may also be a sliding plate. In Figure 2, a passage for passing gas is formed, including a prism 8 for deflecting light for forming small holes 9 on the circumferential surface of the molten metal discharge port 7 of the fixed plate of the sliding nozzle for discharging molten metal. Another laser device 31 is shown for use in the stage embodiment. When processing using the laser device 31, a prism 8 is inserted into the molten metal outlet 7 of the workpiece (fixed plate) 4, the laser beam 25 is reflected using the prism 8, and the molten metal outlet 7 is A small hole 9 or slit is made from the wall 32 of the hole. The means for deflecting the light may be a reflecting mirror instead of the prism 8. Note that 10 is a gas equalization zone and 11 is a gas introduction hole. The pressure of the gas introduced from the gas introduction hole 11 is equalized by the gas pressure equalization zone 10. Gas equalization zone 1
0 and the machined small hole 9 are communicated with each other, and the pressure-equalized gas is supplied to the molten metal outlet 7 through the small hole 9. Details of the laser device 31 including the prism 8 are shown in FIG. The laser device 31 includes a lens 2 that focuses a laser beam 25 emitted from a laser light source, and a prism 8 that deflects a beam 23a focused by the lens 2, and includes a rectilinear portion 34, a deflection portion 35, and a small diameter portion 36. A nozzle 33 having a gas flow hole 37 and an outlet 38 is arranged such that the central axis A of the rectilinear portion 34 is aligned with the center of the molten metal discharge port 7 . The gas is located between the focal point 3 of the focused laser beam 23b and the fixed plate of the sliding nozzle for discharging molten metal as the workpiece 4, and the small diameter 9 from the inner surface 32 of the workpiece 4 communicates with the gas introduction hole 11. Equal pressure zone 1
Processed towards 0. In order to process a plurality of small holes 9, the laser device 31 may be kept stationary and the workpiece 4 may be displaced, or the workpiece 4 may be kept stationary and the laser device 31 may be displaced. Reference numeral 40 denotes a glass plate that partitions the space within the deflection section 35 and is transparent to the laser beam. Note that the glass plate 40 may be omitted. FIGS. 4 to 7 show a sliding nozzle for discharging molten metal comprising fixed plates 13, 15 and a sliding plate 14 processed by a specific example of the processing method according to the present invention. FIG. 4 shows a sliding nozzle having a gas supply body 12 formed with a small hole 22 fitted into a fixed plate main body 13a by the laser device 1 of FIG. The gas supply body 12 is usually fixed to the fixed plate main body 13a with mortar or the like. The small hole 22 is connected to the gas introduction hole 11 via a gas equalization zone 10 provided in the fixed plate main body 13a. The gas supply zone 12 and the fixed plate main body 13a are formed into respective shapes by a hydraulic press after mixing and kneading alumina raw materials as a base material for the gas supply zone 12 and a base material for the fixed plate main body 13a.
The molded base of the gas supply body 12 and the base of the fixed plate body 13a are each fired at about 1600° C. after moisture is removed to 1% or less. The calcined surface of the fired gas supply body 12 and the calcined surface of the fixed plate main stand 13a are impregnated with 5% by weight of tar.
Vacuum impregnated. Vacuum impregnated gas supply body 12
The baked surface and the baked surface of the fixed plate body 13a are each heat-treated at about 300° C., and then surface deposits are mechanically removed. A recess 13b having an opening 13c into which the gas supply body 12 is fitted is formed in the baked surface of the mechanically processed fixed plate main body 13a. In order to obtain adhesion and sliding properties when the fixed plate 13 is used as a sliding nozzle, the surface in contact with the sliding plate 14 is processed with a diamond blade. The mechanically processed gas supply body 12 is burnt using a laser device 1 shown in FIG. 1 with a focal length of 10 inches.
Laser processing is performed by adjusting the focal depth H to 6 mm from the surface and the distance between the tip of the nozzle 5 and the outer surface 21 of the workpiece 4, which will become the gas supply body 12, to 6 mm. _N2 gas with a pressure of 4Kg/ ^cm2 as an auxiliary gas at a flow rate of 70/min
While continuously flowing the gas, a CO ₂ gas laser with an output of 500 W and a frequency of 50 Hz is emitted to obtain a gas supply body 12 having 50 small holes with an average pore diameter of 0.3 mm. Fixing the laser-processed gas supply body 12 to the plate body 1
The fixed plate 13 is obtained by fitting into the recess 13b of 3a. FIG. 5 shows a sliding nozzle in which a gas supply section is provided on the sliding plate 14, 13 is an upper fixed plate, 15 is a lower fixed plate, and the sliding plate 1
4 is provided with a gas introduction hole 16, a gas pressure equalizing zone 17 is provided at the tip thereof, and a plurality of small holes 18 are provided in the sliding plate 14 by the laser device 1 shown in FIG. . and sliding plate 1
When the molten metal discharge port 7 is closed in step 4, the discharge port 7
It blows out gas in the same way as the small hole 22 during melting. FIG. 6 shows the laser device 31 of FIGS. 2 and 3.
A sliding nozzle having a small hole 9 machined in a fixed plate 13 is shown. The small hole 9 connects the molten metal outlet 7 and the gas inlet 11 via a gas equalization zone 10 provided in the fixed plate 13 . FIG. 7 shows a sliding nozzle having a fixing plate 13 machined with slits 19 instead of small holes. Next, examples of the processing method of the present invention will be explained. Example 1 A ring-shaped gas supply body (thickness 15 mm) made of fired high alumina ceramic material is impregnated with tar, and then a CO ₂ laser with an average output of 500 W, a frequency of 100 Hz, and a pulse width of 5 ms is applied from the outside to the focal length of the lens. Ten
Inch, depth of focus (depth from machined surface) 5
mm, the distance between the machined surface and the nozzle tip is 5 mm, and N ₂ gas with a pressure of 3 Kg/cm ² is supplied as an auxiliary gas at 70/min.
The small hole was machined while flowing with the water. After machining 50 holes, the average time required to drill a hole was 1 sec/hole, and a small hole with an average diameter of 0.3 mm was created.
All 50 holes were open. Example 2 A ring-shaped gas supply body (thickness 15 mm) made of the fired high alumina ceramic material used in Example 1 and impregnated with tar was used to determine the average output, frequency, focal length of the lens, depth of focus, and nozzle tip. The distance, the flow rate of the auxiliary gas, and the radiation time were varied as shown in Table 1.

[Table] As shown in Table 1, according to the embodiment of the processing method according to the present invention, small holes of about 0.2 to 1.0 mm can be formed accurately. As the processed product 4 made of a ceramic member, a high alumina ceramic member is used in the above embodiment, but in addition to the ceramic member made of alumina, a ceramic member made of zircon or zirconia can also be processed by the method described above. Ru. Like the alumina workpiece 4, the zircon or zirconia workpiece is also impregnated with tar before the pores are formed. These ceramic members also have higher blackness and are easier to process in order to prevent reflection of laser light during laser light emission. In other parts of the area where the laser beam is emitted, the surface of the ceramic component is protected by the volatilization of volatile components due to the high temperature when the molten metal is discharged, and the residual components remaining in the pores after the volatile components have volatilized protect the surface of the ceramic component. is prevented from entering the pores. Table 2 shows the effects of tar impregnation treatment on some ceramic parts.

[Table] Molten metal was cast using a plate processed by the embodiment of the processing method of the present invention, and the amount of gas supplied was sufficient, so erosion or closure of small holes due to the molten metal hardly occurred. It was superior to products processed using conventional methods and equipment.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional explanatory diagram of a laser device used in a specific example of the processing method of the present invention, FIG. 2 is a cross-sectional explanatory diagram of another laser device used in a specific example of the processing method of the present invention, and FIG. FIG. 2 is a detailed sectional explanatory diagram of another laser device, and FIGS. 4 and 5 are cross sections of sliding nozzles for discharging molten metal, each including a ceramic member processed by the laser device of FIG. 1. The explanatory drawings, FIGS. 6 and 7, are cross-sectional explanatory views of a sliding nozzle for discharging molten metal that includes a ceramic member processed by the different laser devices shown in FIGS. 2 and 3, respectively. 1, 31...Laser device, 2...Lens, 3...
...Focus, 4...Processed product, 5...Nozzle, 6,33
... Auxiliary gas inlet, 8 ... Prism, 9 ... Small hole, 12 ... Gas supply body, 13, 15 ... Fixed plate, 14 ... Sliding plate, 25 ... Laser light.

Claims (1)

[Scope of Claims] 1. A method for processing a ceramic member in which a passage for passing gas is formed in the ceramic member by emitting a laser beam to the ceramic member, the method comprising: preparing a ceramic member; and the prepared ceramic member. immersing the ceramic member in a bath containing either tar or pitch in a vacuum and then heating the ceramic member to impregnate the ceramic member with either the tar or pitch; A method of processing a ceramic member comprising the step of emitting a laser beam to a ceramic member impregnated with one of the pitches to form a passage for gas passage. 2. The processing method according to claim 1, wherein the ceramic member is impregnated with 15% by weight or less of either the tar or the pitch. 3. The processing method according to claim 1 or 2, wherein the ceramic member comprises either a sliding plate or a fixed plate of a sliding nozzle for discharging molten metal. 4. The processing method according to any one of claims 1 to 3, wherein the step of forming a passage for passing the gas includes focusing laser light emitted onto the ceramic member. . 5. The processing method according to any one of claims 1 to 4, wherein the step of forming a passage for passing the gas includes polarizing laser light emitted to the ceramic member. . 6. The step of forming a passage for passing the gas includes spraying a gas onto a portion of the ceramic member that is irradiated with the laser beam to remove the melted material of the ceramic member that has been melted by being irradiated with the laser beam. The processing method according to any one of claims 1 to 5, including: 7. The step of forming passages for passing gas includes keeping the emission of laser light by the means for emitting laser light stationary in order to form a plurality of passages for passing gas through one ceramic member; 7. A processing method as claimed in any one of claims 1 to 6, including the step of displacing the ceramic member and emitting laser light each time the ceramic member is displaced. 8. The step of forming passages for passing gas includes keeping the ceramic member stationary and displacing the means for emitting laser light in order to form a plurality of passages for passing gas through one ceramic member. 7. The processing method according to any one of claims 1 to 6, comprising the step of emitting laser light every time the means for emitting laser light is displaced.