JP2006192496A - Method for applying coating agent to core for casting cast iron tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly perform a liquid-cutting of coating agent in the application of the coating agent (e) by dipping a core 17 for casting. <P>SOLUTION: The core 17 after dipping is rotated around the axis (c) of the core by inclining the core by 30 degrees with respect to the vertical direction of the axis (c). One point at the lower part of the core 17 becomes the lowest part by inclining the core 17, and the coating agent (e) is collected and the collected coating agent (e) is easily dropped down and the liquid-cutting is easily performed. The coating agent (e) is actively shifted with the centrifugal movement by rotating the core, and the liquid-cutting at the lowest part is further promoted and excessive coating agent (e) on the surface of the core 17 is actively shifted on the coated surface with the centrifugal movement and exfoliated without leaving the hang-down trace and also, the coated surface is fully uniformed. Therefore, the liquid-cutting of the coating agent (e) is smoothly performed and the coated surface without the hang-down trace is obtained and the casting surface on the inner surface of a receiving hole in a cast iron tube is made excellent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coating agent coating method for a core to be loaded in a receiving portion when casting a cast iron pipe.

  Centrifugal casting makes it difficult for defects such as blowholes and shrinkage cavities to occur inside the casting, and the material becomes dense, so that a casting with good quality such as mechanical properties can be obtained smoothly. For this reason, cast iron pipes are also manufactured today by centrifugal casting from the viewpoints of good quality and productivity.

For example, as shown in FIG. 1, the cast iron pipe P is manufactured by rotating a cylindrical mold (mold) 11 with a roller 12, and from a ladle 13 to a triangular ladle on the inner surface of the mold 11. The molten metal a is fed into the casting trough 15 through 14 and the molten metal a is cast into the mold 11 through the trough 15 (pouring) to form a cylindrical molten metal layer (tubular body) having a required thickness. It is common to do this (see Patent Documents 1 and 2).
JP 54-38229 A JP 2004-58094 A

  In this centrifugal casting method, as shown in the figure, in order to form the inner surface 1a of the receiving port 1, the core 17 is mounted in the receiving portion of the mold 11, and the core 17 and the inner surface of the mold 11 are formed. The molten metal a is fed into the space (receiving port forming part) to cast the receiving port 1. In the figure, 2 is an insertion slot.

A coating agent is applied to the core 17 in order to prevent the molten metal a from being burned and to obtain a good cast surface. For the application, for example, a so-called soaking method in which the film is immersed in a coating agent tank is employed. At this time, after the core 17 is immersed in the coating agent tank and taken out, so-called soaking of the coating agent (sagging) is required to remove the excess coating agent (liquid reservoir) on the coating surface. It is. This is because if the liquid is not drained, the excess coating agent that has accumulated will sag on the other application surface, and the dripping trace will remain, and the coating agent will be wasted. The sagging marks cause irregularities in the casting surface of the product, leading to shape defects and dimensional defects.
Note that the application of the coating agent also has the effect of improving the surface strength of the core 17 and modifying the surface structure.

For this reason, conventionally, after the core 17 is immersed in the coating agent tank and taken out, it is maintained for about 10 to 30 seconds with its axis inclined at about 45 degrees, and an excess of the surface of the core 17 is obtained. The coating agent is removed (liquid drained) and sent to the drying process (see Patent Document 3, paragraph 0020, FIG. 3).
Further, in order to minimize the operation of running out of liquid, the coating agent is sprayed and applied to the surface of the core 17 while rotating the core 17, and after the application, the rotational speed of the core is reduced to adhere to the core surface. There is also a technique of removing excess coating agent by dropping (see Patent Document 4, paragraph 0019).
JP 2002-254140 A Japanese Patent Laid-Open No. 09-168851

Although the technique of draining the coating agent by inclining the axis of the core 17 of the above-mentioned Patent Document 3 by about 45 degrees is effective as it is, the liquid draining is entrusted to the weight of the coating agent. The liquid draining speed is slow, and the excess coating agent is not sufficiently drained, and the remaining coating agent drips and a dripping trace remains on the coating surface. As described above, the sagging trace causes irregularities in the casting surface of the product, resulting in shape defects and dimensional defects.

  The technique of Patent Document 4 has an advantage that the thickness of the coating layer can be made uniform because it is applied by spraying the coating agent while rotating the core 17, but the apparatus becomes large, and The working environment is deteriorated due to scattering and the coating agent is wasted, and there are cost problems as compared with the case where it is soaked.

  This invention makes it a subject to perform the liquid running out of a coating agent smoothly in such a situation in soaking.

In order to solve the above-described problems, the present invention firstly tilts the core of the soaked core with respect to the vertical direction, and then rotates the core around the axis as in the technique described in Patent Document 4. Therefore, the excess coating agent was removed.
If the core is tilted, the point below the core becomes the bottom, and the coating agent gathers at the bottom, and the collected coating agent is easy to fall off and easily break off. Rotate the coating agent (liquid) to move actively due to centrifugal force, further drainage of the bottom is further promoted, excess coating agent on the core surface is actively activated on the coated surface by centrifugal force It moves and peels off without leaving a sag, and the coated surface is evenly distributed.

  These actions are repeated on the entire outer surface of the core, which is the coating surface, so that the coating surface has a uniform thickness, and the excess coating agent is uniformly and smoothly drained without leaving dripping traces as much as possible. The

In addition, in the technique of rotating in a state where the core is inclined in Patent Document 4 and removing the excess coating agent, the coating is performed by injecting the coating agent while inclining the core. Because of the continuous coating agent removal action, the coating agent removal action also rotates the core in a tilted state, and the advantage of the drainage action by tilting the core in this invention ( The point below the core is the lowermost part, and the coating agent gathers at the lowermost part, and the collected coating agent is not easily recognized by the fact that it is easy to fall off and be easily drained. Further, since application is performed by spraying, there is little liquid accumulation on the application surface, and the effect of removing the coating agent by rotation cannot be expected so much.
In contrast, the present invention relates to application of a coating agent by soaking, and unlike the application of a coating agent by spraying in the technique described in Patent Document 4, the application surface by soaking is sufficient. Although the film thickness can be made easy, liquid pool of excess coating agent is easily generated, and the liquid draining effect by rotation in an inclined state can be greatly expected.

  In the present invention, as described above, since the core is tilted and rotated to remove excess liquid from the coating agent, smooth dripping can be performed without leaving any dripping traces. For this reason, the cast surface of the cast iron pipe receiving inner surface can be made favorable.

  As an embodiment of the present invention, a core for casting a cast iron pipe is chucked with a chuck and immersed in a coating agent tank, and when the coating agent is applied to the core, the core is coated with the chuck. It is possible to adopt a configuration in which the excess coating agent is drained by immersing the core in the agent tank and then rotating the core around the axis by tilting the axis with respect to the vertical direction. .

  At this time, the inclination angle and rotation speed of the core axis with respect to the vertical direction may be appropriately set by experiment, actual operation, etc. in consideration of the moving state of the coating agent, the degree of the occurrence of dripping, etc. The inclination angle is preferably about 20 to 60 degrees. If you leave this range, the area at the bottom below the core widens (does not get close to the point), and the concentration of the coating agent at the bottom decreases, making it difficult to fall off and difficult to drain. is there. In the experiment described later, around 30 degrees was good.

  If the core is made of sand when the coating agent is applied by this soaking, before the core is immersed in the coating agent tank, the surface to be coated of the core is air blown to bond the core. It is preferable to peel the weak sand. This is because the peeled sand becomes floating particles in the coating agent tank when it is soaked, and if it remains on the coating surface after applying the coating agent, it is likely to cause the biting of foreign matter.

Also, a porous container is submerged in the coating agent tank, and the core is immersed in the container, so that sand particles that are detached from the core and float and settle in the coating agent tank are captured by the container. It is preferable to make it. In this way, for example, after completion of the day's work, the container is lifted from the coating agent tank, and the sand particles floating and settling in the coating agent tank are taken out, so that It is possible to prevent the sand from accumulating as much as possible, and thereby it is possible to suppress the sand from being mixed into the coating material application surface.
As the container, a sieve made of a perforated plate having a hole diameter capable of catching sand, for example, made of a material such as punching metal or a wire mesh, or the like is adopted.

Furthermore, if a blocking plate that prevents the inflow of the coating agent into the core is provided in the core, since the invasion of the coating agent into the inner surface of the core that does not require application of the coating agent is prevented, The waste of the coating agent is reduced, and deterioration of the core due to the penetration of the coating agent into the inner surface of the core can be prevented.
At this time, if the closing plate is provided on the chuck so that it can be moved into the core, the closing plate can be moved together with the chuck to facilitate handling such as contact with the core, and the core can be rotated. When the soaking plate is soaked, the core portion where the closing plate is in contact is separated from the core portion, thereby facilitating the drainage of the core portion.

Moreover, as a mode of the said obstruction | occlusion board, the obstruction | occlusion board can be provided in the said coating agent tank through a spring, and the surface of the obstruction | occlusion board can always employ | adopt the structure which protruded from the coating agent surface by the spring.
In this configuration, when the core is pressed against the closing plate, the closing plate is pressed down against the spring while preventing the coating agent from flowing into the core. Further, if the core is pulled up from the coating agent tank and separated from the coating agent liquid surface, the closing plate is also separated from the core, and the breakage of the core portion that has been in contact with the closing plate is promoted.

  In this embodiment, the coating agent e is applied to the outer peripheral surface of the core 17 shown in FIG. 1 by dipping. The surface to be coated of the core 17 is first blown by air to weaken the bonding force. Remove the sand. Further, the waste 9 is submerged in the coating agent tank 6.

  Next, as shown in FIG. 2 (a), the core 17 is suspended in the vertical direction by the chuck 5, and in the suspended state as shown in FIG. It is immersed in the tank 6 of e. At this time, the suspension rod 7 extends inside the core 17 on the central axis of the chuck 5 and a closing plate 8 such as an iron plate is provided at the end thereof. The opening of the core 17 is closed by the closing plate 8. Is done. For this reason, the penetration of the coating agent e into the inner surface of the core 17 which does not require application of the coating agent e is prevented, and the coating agent e is not wasted. The chuck 5 chucks the core 17 with its inner surface as its claws 5a advance and retract in the radial direction from the center.

After soaking for a sufficient time, as shown in FIG. 2 (c), the core 17 is pulled up right above the coating agent tank 6, and further, as shown in FIG. The axis c is inclined in the vertical direction so as to have a required angle θ, and the core 17 is rotated around the axis c in the inclined state.

If the core 17 is tilted, one point below the core 17 becomes the lowermost part, and the coating agent e gathers at the lowermost part. If the core is rotated, the coating agent e moves actively due to centrifugal force, and the liquid drainage at the bottom is further promoted, and the excess coating agent e on the surface of the core 17 moves on the coating surface by centrifugal force. It moves actively and is peeled off without leaving a sag, and the coated surface is evenly distributed.
When the liquid draining operation is completed (if the coating surface is leveled and there are no dripping traces), the core 17 is moved to the next drying step. Thereafter, in the same manner, the coating agent e is sequentially applied to the uncoated core 17.

  When application of the coating agent to the required number of cores 17 is completed, for example, after completion of a day's work, the sand 9 is lifted from the coating agent tank 6 and floats and settles in the coating agent tank 6. Remove the particles.

  In this example, the immersion time of the core 17 is 1 to 3 seconds, the rotation speed is 2.5 to 5 rpm, each inclination angle θ is 30 to 40 degrees, and the rotation time is 15 to 30 seconds. Cutting was made smoothly, and in particular, the inclination angle θ of the core 17 was preferably about 30 degrees.

If the closing plate 8 can be moved back and forth with respect to the chuck 5, it can cope with a change in the length of the core 17 in the axial direction, and at the time of rotation, as shown in FIG. It is possible to promote liquid breakage at the part where the closing plate 8 of the core 17 is in contact with the upper part.
Further, as shown in FIG. 3, a floating type closing plate 8 made of styrene foam or the like is floated in the coating agent tank 6, and the core 17 is soaked while the closing plate 8 is submerged as shown by the chain line in FIG. It can also be performed (see Patent Document 3).

Further, as shown in FIG. 4, a closing plate 8 is provided (fixed) in the coating agent tank 6 via a spring 8a, and the surface of the closing plate 8 is a spring 8a as shown in FIG. Therefore, it can be made to come out from the surface of the coating agent e at all times.
In this configuration, as shown in FIGS. 2B to 2C, the core 17 is brought into contact with the closing plate 8 and pushed down, whereby the closing plate 8 is applied to the inside of the core 17 as a coating agent e. It is pushed down against the spring 8a while preventing inflow.
At this time, since the closing plate 8 is supported by the spring 8a, the movement is smooth. The blocking plate 8 may be a polystyrene foam, but if a hard plate such as a hard resin plate, a stainless plate, a rust-preventing iron plate, or an aluminum plate is used, the durability will be good.

Schematic diagram of centrifugal casting Action diagram of one embodiment Operational diagram of this embodiment Operational diagram of this embodiment Operational diagram of this embodiment Operational diagram of another embodiment Operational diagram of another embodiment Operational diagram of this embodiment Operational diagram of this embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Portion of cast iron pipe 2 Insertion port 5 Core chuck 6 Coating agent tank 8 Closure plate 8a Spring 9 Zu (container)
11 Mold 17 Core a Molten metal e Coating agent P Cast iron pipe

Claims (5)

  When the core 17 for cast iron pipe casting is chucked by the chuck 5 and immersed in the coating agent tank 6 and the coating agent e is applied to the core 17, the core 17 is moved by the chuck 5. After being immersed in the coating agent tank 6 and taken out, the core 17 is rotated around the axis c with its axis c inclined relative to the vertical direction to drain off the excess coating agent e. A casting mold coating method for a core for casting.   2. The coating agent coating method for a core for casting a cast iron pipe according to claim 1, wherein an inclination angle [theta] with respect to a vertical direction of the core 17 axis c is set within 20 to 60 degrees.   The method of applying a coating agent for a core for casting a cast iron pipe according to claim 2, wherein an inclination angle θ of the core 17 axis c with respect to a vertical direction is set to about 30 degrees.   The core 17 is made of sand, and before the core 17 is immersed in the coating agent tank 6, the surface to be coated of the core 17 is air blown to separate the sand having a weak binding force. A coating agent coating method for a core for casting a cast iron pipe according to any one of claims 1 to 3.   A porous container 9 is submerged in the coating agent tank 6, the core 17 is immersed in the container 9, and the sand particles that are separated from the core 17 and float and settle in the coating agent tank 6 are The method for applying a coating agent to a core for casting cast iron pipe according to claim 4, wherein the core 9 is captured by the container 9.

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