JP4289777B2 - Centrifugal casting chute coating method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of coating a chute for centrifugal casting.
[0002]
[Prior art]
One method for producing a cast iron pipe is a centrifugal casting method. The centrifugal casting method is a method in which a molten cast iron is supplied to a cylindrical mold rotating at high speed, and a tubular body is cast by applying centrifugal force to the supplied molten metal. FIG. 3 shows an example of the centrifugal casting method.
[0003]
As shown in FIG. 3, there is a centrifugal casting apparatus 1, and a portion that becomes a mold inside the centrifugal casting apparatus 1 is an inner peripheral surface of a cylindrical mold 2 and a cylindrical core 3. It is comprised from the outer peripheral surface. The mold 2 has a water-cooled jacket structure (not shown), can rotate at high speed, and the core 3 is attached to the core setter 4 so as to be in a fixed position with respect to the mold 2. The cast iron melt 5 cast into the centrifugal casting apparatus 1 is poured from the ladle 6 to the chute 7 and supplied to the inner peripheral surface of the mold 2 through the trough 8. The chute 7 is a curved surface portion that receives the molten metal 5 from the ladle 6, and the trough 8 is a straight portion that is gently inclined to supply the molten metal 5 received by the chute 7 to the inner peripheral surface of the mold 2.
[0004]
In the centrifugal casting apparatus 1 having the above-described configuration, the cast iron melt 5 is poured from the ladle 6 to the chute 7 and supplied to the inner peripheral surface of the mold 2 rotating at high speed through the trough 8. Since the centrifugal force acts on the supplied molten metal 5, the cast iron pipe 9 can be formed.
[0005]
In such a method of centrifugal casting of a tube, metal oxides formed by oxidizing the remainder of the molten metal 5 adhere to the surfaces of the chute 7 and the trough 8 after the tube is manufactured. The attached metal oxide is removed by reversing the chute 7 and the trough 8 and applying an impact. The chute 7 and the trough 8 are made of steel (cast steel) because they must withstand this repeated impact. is there.
[0006]
Thus, the chute 7 and the trough 8 formed of the same material as the molten metal 5 are, for example, graphite-based coating molds after each casting so that they do not melt even if the molten metal 5 falls from the ladle 6. It is necessary to protect the surfaces of the chute 7 and the trough 8 by applying a blacking material. As an example of the composition of the blackening material, which is a graphite-based coating mold, with a ratio of 20 kg of carbon black, 5 kg of scaly graphite, 0.6 kg of bentonite, and 1 liter of water glass per 230 liters of water. There is something to mix.
[0007]
When a coating mold for protecting the surfaces of the chute 7 and the trough 8 is applied, the surfaces of the chute 7 and the trough 8 after casting are cooled as shown in FIG. 10 is performed from the top of the chute 7. At this time, the thin graphite-based coating die 10 poured out from the outlet 11 of the supply pipe for the blacking material flows from the upper part of the chute 7 through the lower part of the chute 7 and is applied to the trough 8. Next to this blanking, as shown in FIG. 4B, a graphite-based coating mold 12 having the same components as the coating mold 10 and having a higher concentration than the coating mold 10 is applied to the brush 13 from above the coating mold 10. Then apply from the top of the chute 7 to the bottom.
[0008]
However, since the brush coating operation is a manual operation, if the coating method is uneven, the coating mold 12 may be peeled off from the inner surface of the chute 7 and bitten into the product. For this reason, as shown in FIG. 5, when the operation of applying the brush on the coating mold 12 is sprayed with the injector 15, the coating mold 12 is vigorously moved to obtain a more uniform coating film with high adhesion. Spray on the inside.
[0009]
[Problems to be solved by the invention]
However, as shown in FIG. 5, the chute 7 is inclined, and if the amount of spraying the coating mold 12 is vigorously sprayed, it droops and a stagnation 14 is formed, which is bitten into the product. Moreover, if the spraying state of the coating mold 12 sprayed from the injector 15 is made fine and sprayed to prevent dripping, the adhesiveness of the coating mold 12 is lowered.
[0010]
Therefore, in the present invention, the purpose is to obtain a more uniform coating film by preventing the occurrence of stagnation by removing dripping that occurs when the spraying of the coating mold is performed using an injector. To do.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, according to the first aspect of the present invention, when applying a coating to a chute for centrifugal casting of a tube, a dark coating is sprayed downward from the upper part of the chute, and then a thin coating is applied to the lower part of the chute. By performing the blacking using the above, when there is an unnecessary portion of the dark coating mold sprayed first, the unnecessary portion is washed away.
[0012]
In this way, when an operation to pour the coating mold with good adhesion is performed, if there is an unnecessary portion of the thick coating mold that has been sprayed, the unnecessary portion is washed away, thereby preventing the accumulation. Thus, it is possible to obtain a more uniform coating film.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1 (a), there are a chute 7 and a trough 8, and the spray mold 15 sprays the coating mold 12 from the upper part to the lower part of the chute 7 vigorously. As an example of blending the components of the coating mold 12, as described above, with respect to 230 liters of water, 20 kilograms of carbon black, 5 kilograms of scaly graphite, 0.6 kilograms of bentonite, and 1 liter of water glass are mixed. There is a dark paint. In this way, when the dense coating mold 12 is sprayed vigorously from the upper part to the lower part of the chute 7 by the injector 15, dripping occurs on the inner surface of the chute 7. May occur.
[0014]
Next, as shown in FIG. 4 (a), the blacking, which is the work of pouring the thin graphite-based coating mold 10 as described above, is carried out from the lower portion of the inner surface of the chute 7 as shown in FIG. 1 (b). Go to 8. As an example of the composition of the coating mold 10 component, 16.7 kg of carbon black, 4.2 kg of scaly graphite, 6.5 kg of bentonite, 180 g of magnesium oxide, and 9.5 kg of molasses per 2200 liters of water. Some mix in proportion.
[0015]
The coating mold 10 poured into the lower portion of the inner surface of the chute 7 by the outlet 11 has a reservoir 14 of the coating mold 12 in the lower portion of the inner surface of the chute 7 before the pool 14 is dried. The trough 8 is applied while the reservoir 14 is poured away into the trough 8. At this time, the coating mold 12 and the coating mold 10 are mixed, but since the coating mold 12 and the coating mold 10 are similar coating molds, there is no problem in the performance of protecting the inner surface of the chute 7.
[0016]
The relationship between the amount of spraying the coating mold 12 on the inner surface of the chute 7 and the amount of coating mold 10 necessary for blacking the lower surface of the inner surface of the chute 7 and the trough 8 is, for example, a spray amount 30 The amount of blacking is about 1000 to 3500 cc with respect to ˜100 cc.
[0017]
In this way, the blacking is performed from the lower part of the chute 7 to the trough 8, and if the reservoir 14 of the coating mold 12 is generated, the blacking is performed so that it is washed away. The coating mold 12 has a high adhesiveness and a more uniform coating film remains. From the bottom of the chute 7 to the trough 8, the coating mold 10 is applied without any problem. Therefore, it is possible to obtain a high-performance coating film that protects the chute 7 and the trough 8 and to reduce the bite of the coating mold into the product. Furthermore, by eliminating the brushing operation, which is a manual operation, the number of workers required for applying the coating mold 12 can be saved.
[0018]
In addition, as described above, the work of performing the conventional blacking is also performed for cooling the chute 7, and in the embodiment of the present invention, in the place where the upper blacking of the chute 7 is not performed, Instead, the cooling effect of the upper part of the chute 7 can be supplemented by cooling the chute 7 from the outer surface 16 of the chute 7 by an appropriate method as needed.
[0019]
For example, as shown in FIG. 2, a drive device 17 is provided in a double centrifugal casting device 21 capable of producing two tubes at a time, and this driving device 17 is a mold 2 of the centrifugal casting device 21. It can be slidable along the rail 18 in a horizontal direction perpendicular to the axial direction. The centrifugal casting device 21 and the ladle 6 are fixed with respect to the sliding direction of the driving device 17.
[0020]
The drive unit 17 is provided with a total of four chute troughs, that is, two chute troughs 19 that are used in a single pipe manufacturing process and two chute troughs 20 that are not used.
[0021]
When the series of pipe manufacturing processes is completed, the driving device 17 does not use the chute trough 19 used in the current process in the next process, and uses the chute trough 20 not used in the current process in the next process. Now slide along the rail 18 for use.
[0022]
By applying the present invention to a pipe casting method in which the drive device 17 is slid along the rail 18 for each pipe manufacturing process and the chute and trough are alternately used, Since the coating mold can be applied to the two chute troughs that are not used during the manufacturing operation, and the drying time of the applied coating mold can be extended, the bite of the coating mold into the product is reduced. Better chute trough protection is possible.
[0023]
【The invention's effect】
As described above, according to the present invention, when a thick coating mold is sprayed vigorously from the upper part to the lower part of the chute, dripping occurs on the inner surface of the chute, and due to this dripping, the thick coating mold is accumulated on the lower part of the inner surface of the chute. However, if a thick paint puddle is generated, pour the thin paint mold from the bottom of the chute into the trough and shoot the thin paint mold to remove it. Since it flows from the lower part of the inner surface to the trough, a highly uniform coating can be left on the upper part of the inner surface of the chute. Therefore, it is possible to obtain a high-performance coating film that protects this through the chute and trough, and it is possible to reduce the biting of the coating mold into the product by eliminating the accumulation generated on the inner surface of the chute. Furthermore, by eliminating the brushing operation, which is a manual operation, the number of workers required for applying the coating mold can be saved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a plan view showing an embodiment of the present invention.
FIG. 3 is a cross-sectional view showing an outline of a centrifugal casting method for a cast iron pipe.
FIG. 4 is a cross-sectional view showing a conventional centrifugal casting chute coating method.
FIG. 5 is a cross-sectional view showing a technical problem in a conventional centrifugal casting chute coating method.
[Explanation of symbols]
7 Chute 10 Paint mold 12 Paint mold 14 Pool

Claims (1)

When coating the tube chute for casting, it was sprayed first by spraying a dark coating downward from the top of the chute and then using a thin coating at the bottom of the chute. A casting method for a chute for centrifugal casting, characterized in that when an unnecessary portion of a dark coating mold exists, the unnecessary portion is washed away.

Images