JP6359487B2 - Centrifugal casting apparatus and inoculant spraying method in the apparatus - Google Patents

Description

  The present invention relates to a centrifugal casting apparatus for manufacturing a ductile cast iron pipe and the like, and a method for spraying an inoculum in the apparatus.

  Production of ductile cast iron pipe made of spheroidal graphite cast iron, for example, centrifugal casting of NS type ductile cast iron pipe shown in FIG. The molten metal c is fed into the casting trough 5 through the pipe, the trough 5 is moved in the axial direction in the mold 1 and the molten metal c is cast into the mold 1 (pouring), and has a cylindrical shape with a required thickness. A molten metal layer (cast iron pipe) A is formed (see Patent Document 1, paragraph 0025, FIG. 8).

  At this time, in spheroidal graphite cast iron, inoculation is performed in order to improve mechanical properties. However, since the fading speed of this inoculation effect is large, it is preferable to inoculate the molten metal c as soon as possible. For this reason, in centrifugal casting using the trough 5, an inoculation pipe (inoculation pipe) 10 is attached beside or below the trough 5, and the molten metal into which the inoculum b is injected from the opening end of the pipe 10 by air blow. It sprays on c directly, or it sprays on the mold 1 inner surface (refer patent document 2, summary, paragraph 0002, FIG. 1, FIG. 3).

JP 2005-288475 A JP 2001-293546 A

As shown in FIG. 5, the conventional inoculation tube 10 is sprayed (dispersed) by attaching a downward elbow pipe (pipe) to the tip of the inoculation pipe 10 and from the elbow pipe 6 the inoculant b is applied to the inner surface of the mold 1. Blowing.
The spraying of the inoculant b from the elbow pipe 6 is strongly applied to the narrow area of the inoculant b, and the molten metal c is easily disturbed, and the molten metal c splashed by the disturbance is bitten into the outer surface of the molded product (cast iron pipe) A. Thus, the appearance quality of the cast iron pipe A is adversely affected.
If the air pressure is lowered in order to eliminate the disturbance of the molten metal c, the smooth transfer and spraying of the inoculum b cannot be performed, or the inoculation tube 10 may be clogged. For this reason, the air pressure cannot be lowered.
Moreover, inoculation with the elbow tube 6 is inoculated with the inoculum b in a narrow range and becomes a lump, and the lump adheres spirally to the inner surface as the mold 1 rotates and is difficult to be uniformly spread over the inner surface. When the inoculant b is hardened, the appearance quality of the cast iron pipe A is adversely affected by biting into the outer surface of the cast iron pipe A as described above.

  This invention makes it a subject to spread | disperse the inoculant b uniformly over the mold inner surface wide area, without lowering | hanging an air pressure under the above actual condition.

In order to achieve the above object, the present invention is configured such that the inoculum b discharged from the inoculation tube 10 is gradually directed toward the inner surface of the mold in the axial direction of the tube 10.
If the inoculum b toward the inner surface of the mold 1 becomes stepwise in the axial direction of the inoculation tube (mold), the spraying force (air pressure) is suppressed accordingly, and the inoculum b is also uniformly distributed over the inner surface of the mold. Is done. For this reason, the disturbance of the molten metal c is suppressed and the biting is also suppressed without lowering the air pressure.

The centrifugal casting apparatus according to the present invention includes a mold that rotates about an axis, a trough for casting a molten metal that moves relative to the mold in the axial direction of the mold, and advances and retreats in the mold, and the trough. In a centrifugal casting apparatus having an inoculation tube for spraying an inoculum from the opening of its tip by air blow, a pipe having an open bottom surface is extended (provided by extension) at the tip of the inoculation tube, and the pipe is long. It is possible to adopt a configuration in which a plurality of vertical partition walls are provided at predetermined intervals in the vertical direction and through holes are formed in each partition wall.
The pipe can be on the same axis as the inoculation tube, can be inclined upward or downward, and can be inclined laterally (laterally), and the inclination angle can be smoothly inoculated. As appropriate, it is set by experiment.

In this configuration, if each of the partition walls is provided so as to be inclined downward toward the tip of the pipe, the inoculum moves in the direction in which the molten metal is sent out (pouring), so that the inoculation action is smooth. Become.
Moreover, if each said through-hole is made on the same axis | shaft, an inoculum will pass smoothly through a partition, and if the magnitude | size of a through-hole is made small sequentially toward a pipe tip, the inoculant which will pass through a partition The amount of the inoculum is spread evenly and gradually.

In addition, as a method for spraying the inoculum in the centrifugal casting apparatus according to the present invention, a mold that rotates around the axis, and for molten metal casting that moves relative to the mold in the axial direction of the mold and advances and retreats in the mold. In the method of spraying (supplying / inoculating) an inoculum with the inoculation tube in a centrifugal casting apparatus having a trough and an inoculation tube attached to the trough and spraying the inoculum from the tip opening by air blow The inoculum blown forward in the axial direction from the tube is blocked by a plurality of partition walls provided at a predetermined interval in the axial direction of the inoculation tube, and the inoculum is passed through the through holes of the partition walls, and the inoculum The structure which sprays can be employ | adopted.

In this way, since the inoculum that is blown out is blocked by the partition wall, the inoculum that hits the partition wall falls downward, and the inoculum that has passed through the through-hole of the partition wall further hits the next partition wall and falls. The inoculum is uniformly spread over the inner surface of the mold, and the turbulence of the molten metal is suppressed and the biting is also suppressed.
Also in this structure, each said partition can be provided in the downward slope toward the discharge direction of the said air blow, and the inoculum obstruct | occluded by the partition can be spread diagonally forward. Moreover, each said through-hole can be made on the same axis | shaft, or the magnitude | size of each through-hole can be made small sequentially toward an inoculation tube front-end | tip.

  Since the present invention is configured as described above and the inoculum discharged from the inoculation tube is directed toward the inner surface of the mold stepwise toward the axial direction of the tube, the spraying force is suppressed and the spraying force is reduced. It is not necessary to lower (air pressure), and the inoculum is evenly spread over a wide area, so that turbulence of the molten metal is suppressed and biting is also suppressed. For this reason, a cast iron pipe with improved appearance quality can be obtained.

Schematic sectional view of an embodiment of a centrifugal casting apparatus according to the present invention Cut front view of essential parts of the embodiment The side view or sectional drawing of the principal part is shown, (a) is the left side, (b) is the II sectional view taken on the line in FIG. 2, (c) is the right side. Main part cutting front view of other embodiment Cutaway front view of the main part of the conventional example

  One embodiment is shown in FIGS. 1 to 3, and the centrifugal casting apparatus of this embodiment is for centrifugal casting NS type ductile cast iron pipe A shown in FIG. Is rotated by the roller 2 and the molten metal c is fed from the ladle 3 to the trough 5 for casting through the triangular ladle 4, and the trough 5 is moved in the axial direction in the mold 1 to move the molten metal c into the mold 1. And inoculating agent b is discharged by air blow from a pipe (inoculation pipe) 10 beside the trough 5 to form a cylindrical molten metal layer (cast iron pipe) A having a required thickness. In the figure, B is a core, which is mounted on the mold 1 by a core mounting machine.

In such a centrifugal casting apparatus, in this embodiment, a pipe 11 having a reverse U-shaped cross section (with a slit formed on the lower surface) of the lower surface opening 12 on the same axis is flanged at the tip of the pipe 10 serving as the inoculation tube. A plurality of partition walls 13a, 13b, 13c, and 13d (generic symbol: 13) in the vertical direction are provided in the pipe 11 having the opening 12 at a required interval in the length direction. .
Both pipes 10 and 11 may be screwed together or configured by a single pipe without being bolted through the flange 15. The tip of the pipe 11 is set at an appropriate position on the rear side (right side in FIG. 1) from the tip of the trough 5 so as not to be affected by the pouring of the molten metal c.

The interval between the partition walls 13 is set to an equal interval or the like, gradually narrowed toward the tip of the pipe 11, or gradually widened, etc. so that the optimal inoculum b can be sprayed. Set appropriately according to the experiment. Further, the number of the partition walls 13 is arbitrary, and the opening 12 may not be provided along the entire length of the pipe 11. Further, the final partition wall 13d can be omitted. The length of the pipe 11 is also set appropriately by experiments or the like so that the optimal inoculum b can be sprayed in the same manner in consideration of the distance between the partition walls 13 and the like.
Each partition wall 13 is inclined downward toward the tip of the pipe 11. Further, through-holes 14a, 14b, 14c (general symbol 14) are formed on the same axis e (axial center of the pipe 11) in each partition wall 13a, 13b, 13c, and the size of each through-hole 14 is set to the size of the pipe 11. The size is gradually reduced toward the tip. The degree of change in the size of the through-holes 14 is also set appropriately by experiments or the like so that the optimal inoculum b can be sprayed.

At the time of manufacturing the ductile cast iron pipe A by the centrifugal casting apparatus having this configuration, the inoculating agent b discharged by the air blow through the pipes 10 and 11 is provided with a plurality of partition walls 13 in order in the discharge direction, and is transparent. Since the holes 14 are also getting smaller in order, the strength of the air blow shown in FIG. 2 is gradually reduced as shown by the arrows, and the passing amount of the inoculum b through each partition wall 13 is also reduced step by step. Eventually, it hits the final partition wall (lid plate) 13d without through holes and falls downward.
In this way, the amount (spraying amount) of the inoculum b toward the inner surface of the mold 1 becomes stepwise in the axial direction of the mold 1, and the spraying force is suppressed accordingly, and the inoculum b is evenly spread over a wide range. Therefore, the disturbance of the molten metal c is also suppressed and biting is also suppressed.

At this time, since the partition wall 13 is inclined downward toward the tip of the pipe 11, the air blow is not weakened more than necessary, and the inoculum b is smoothly discharged (spread) over a wide range. The inclination angle θ of the partition wall 13 may be appropriately determined by experiments or the like so that the inoculum b can be smoothly dispersed. In this embodiment, θ = 45 degrees.
FIG. 4 shows an embodiment in which the partition wall 13 (13a, 13b, 13c, 13d) is lowered vertically. At this time, the partition wall 13 may be inclined rightward (inclined downward toward the rear end of the pipe 11).

In the above embodiment, the pipe 11 can be inclined downward as in the case of a conventional vent pipe, or conversely upward, even if not on the same axis as the inoculation pipe 10, The angle of inclination can be set appropriately by experiment or the like so that smooth inoculation is possible.
The through holes 14a, 14b, and 14c may not be on the same axis but may be shifted vertically and horizontally. In addition, the size of the inoculum is the same without reducing the size toward the tip of the pipe 11 one after the other, the front and back are reversed (the front through hole is smaller than the rear through hole), etc. As long as smooth discharge of a wide range of b is performed, it is arbitrary.
Further, a plurality of the through holes 14 may be provided in one partition wall 13, and in an extreme case, may have a net structure. In the case of a net structure, the amount of inoculum b passing through each partition wall 13 is adjusted by adjusting the degree of mesh.

The above embodiment is the case of NS type cast pipe A centrifugal casting, but cast iron pipe A of each form such as S form, US form, UF form, K form, T form, U form, PN form, PII form, etc. It goes without saying that the present invention can be adopted for the centrifugal production of the above.
Thus, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

A Cast iron pipe b Inoculum c Molten metal 1 Mold (mold)
2 Mold support roller 3 Ladle 4 Triangular ladle 5 Hot water trough 6 Elbow pipe 10 Inoculation pipe (pipe)
11 Pipe for spraying inoculum 12 Opening of pipe 11 (slit)
13, 13a, 13b, 13c, 13d Bulkhead 14, 14a, 14b, 14c Through-hole 15 Flange for connection

Claims (8)

A mold (1) that rotates about an axis, a trough (5) for casting a molten metal that moves relative to the mold (1) in the axial direction of the mold (1), and advances and retreats into the mold (1); An inoculation tube (10) attached to the trough (5) and spraying the inoculant (b) from the tip opening by air blow,
A pipe (11) having a lower surface opening (12) is extended at the tip of the inoculation pipe (10), and a plurality of vertical partitions (13a, 13b, 13c), and a through hole (14a, 14b, 14c) is formed in each partition wall (13).   The centrifugal casting apparatus according to claim 1, wherein each of the partition walls (13) is provided so as to be inclined downward toward the tip of the pipe (11).   The centrifugal casting apparatus according to claim 1 or 2, wherein the through holes (14a, 14b, 14c) are on the same axis (e).   The centrifugal casting apparatus according to any one of claims 1 to 3, wherein the size of each of the through holes (14a, 14b, 14c) is sequentially reduced toward the tip of the pipe (11). A mold (1) that rotates about an axis, a trough (5) for casting a molten metal that moves relative to the mold (1) in the axial direction of the mold (1), and advances and retreats into the mold (1); The mold (1) by the inoculation tube (10) in a centrifugal casting apparatus having an inoculation tube (10) attached to the trough (5) and spraying the inoculum (b) from the tip opening by air blow A method of spraying the inoculum (b) into the inside,
The inoculum (b) blown forward in the axial direction from the inoculation tube (10 ) is blocked by a plurality of partition walls (13a, 13b, 13c) provided at required intervals in the axial direction of the inoculation tube (10). The inoculant spraying method in a centrifugal casting apparatus, wherein the inoculant (b) is passed through the through holes (14a, 14b, 14c) of each partition wall and the inoculant (b) is sprayed.   Each of the partition walls (13a, 13b, 13c) is provided with a downward slope toward the air blow discharge direction, and the inoculum (b) blocked by the partition wall is sprayed obliquely forward. An inoculum spraying method in the centrifugal casting apparatus according to claim 5.   The method for spraying an inoculum in a centrifugal casting apparatus according to claim 5 or 6, wherein the through holes (14a, 14b, 14c) are on the same axis (e).   The centrifugal casting apparatus according to any one of claims 5 to 7, wherein the size of each of the through holes (14a, 14b, 14c) is sequentially reduced toward the tip of the inoculation tube (10). Inoculum spraying method.

Images