JPS60170555A - Improved type neck-down core - Google Patents

Abstract

PURPOSE:To reduce man-hour for finishing by providing a fine belt-like neck hole forming a fracture surface and an annular projecting line in proximity to the aperture edge of the neck hole to a neck-down core to permit breakage and sepn. of a riser and product by impact force. CONSTITUTION:An improved type neck-down core 3 consists in having a thin sheet-like projection 5 provided on a riser side 4, a fine belt-like neck hole 6 forming a fracture surface, a projecting line 9 provided peripherally into a ring shape to the aperture edge of the hole 6 on the product 8 side in proximity thereto and a notched edge 7 to determine the position of the fracture surface. The core 3 is inserted to the boundary between a riser 1 and a product 2. The riser 1 and the product 2 are broken and separated after solidification. The sectional area of the hole 6 is reduced by such core 3 and the man-hour for finishing is considerably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION A) Industrial Field of Application The present invention relates to a neck-down core that is used in metal casting to interpose a neck-down core at the boundary between the feeder and the product, and to break and separate the feeder and the product by impact force. Regarding performance improvement.

B) Prior Art and Problems As is well known, castings are cast by pouring molten metal into a mold, but generally the molten metal shrinks when it physically solidifies.

Therefore, in order to compensate for the amount of shrinkage, it is necessary to install a riser in the product, and when solidification is completed after casting, the mold is opened and the riser is generally cut with gas or a neck-down core to prevent breakage due to impact force. will be removed. Gas cutting may not be possible depending on the material of the molten metal to be cast, or the thermal effect on the product is large, and if the material is particularly sensitive to heat, there is a risk of cracking due to gas cutting. It is necessary to perform fracture separation using a neck-down core. Furthermore, even if the material is gas-cuttable, a neck-down core may be used to save cutting man-hours and post-cutting finishing man-hours. Figures 1 and 2 show a generally used neck down core (3), and the neck hole (6) is often round. Usually in this case the product after rupture (
2) The seat (12) remains as an integral part and must be removed by grinding or the like. The shape of the neck-down core (3) as shown in Fig. 3 was developed in 1987-31 with the purpose of eliminating the finishing process for removing such a seat (12).
014. In this case, in order to lower the desired fracture surface below the product surface in advance, a convex portion is provided on the product side (8) of the core, and the shape is such that the fracture surface is located below the product surface. If the concave part is larger than the cross section of the product (
2), and in some cases there are problems with manufacturing specifications, and if the location where a feeder is required is important for the product shape, the feeder cannot be installed. In addition, depending on the material or the size of the neck hole (6), regardless of whether it is a general type or a special type according to Japanese Patent Publication No. 51-31014, in reality, it does not necessarily always break in a plane at the notch edge (7), as shown in Fig. 4. As shown in Fig. 5, the protrusion (13) remains integrally on the product (2) through the seat (12), and the finishing work is characterized by a great deal of labor. If the deadline is moved forward,
A product with a feeder is in a red-hot state, and a portion of the feeder (1), which solidifies slowly, passes through the seat (12) and remains on the product (2) as a protrusion (13) at a very high rate. Under these circumstances, the smaller the area of the neck hole (6) is, the easier it will be to break at the desired location, i.e., the notch edge (7) (it will require fewer finishing steps, but the reduction in the cross-sectional area of the feeder connection will ensure continued hot water supply). This is undesirable as it reduces the time and reduces the feeder effect.Therefore, it is desirable that the neck hole (6) has the minimum size that can maintain the feeder effect.

Normally the size of the neck hole (6) is the size of the riser (1) and product (2).
It is determined experimentally by the capacity of the molten metal, the material of the molten metal, etc., and is also influenced by the 4rA quality of the neck-down core (3).

C) Technical Problems of the Invention The present invention has been developed in view of the above circumstances, and it is possible to easily and accurately break the desired notch edge (7) at room temperature or in a red-hot state, and to reduce the number of finishing steps after the break. was considered a technical issue.

D) Technical means of the invention In the neck-down core (3) that is charged at the boundary between the riser (1) and the product (2) of the mold and breaks and separates the riser (1) and the product (2) after solidification. On the riser side (4) there is a thin plate-like projection (
5) is integrally installed so that the neck hole (6) that forms the fracture surface is shaped like a narrow strip, and the notch edge (7) that determines the position of the fracture surface is arranged on the same plane as the product side (8). (8) has a ring-shaped protrusion (9) close to the opening edge of the neck hole (6).
This is an improved neck-down core that is characterized by having

E) Example An example of a neck-down core of a cast product manufactured according to the present invention will be described with reference to the drawings. Figures 6 and 7 show the shape of the neck-down core (3) in the case of a horizontal riser. product(
In this embodiment, a thin plate-shaped projection (5) is provided on the feeder side (4) at a position below the center of the height of 2) in a U-shape integrally with the neck-down core (3). Its dimensions are approximately 7 mm thick x 40 mm high. Directly above it, that is, the product (2
) A drilled hole (6) is provided at a position above the center of the height of the cutout edge (7) on the product side (8) so that it is flush with the cutout edge (7). The shape of the neck hole (6) was a narrow strip of 6 mm x 80 mm, and the cross section was similar to that of a Paris weir for cast iron. Further, the notch angle θ of the notch edge (7) was set to 45° in this embodiment since the material was made of a high hardness material. In addition, on the product side (8), a protrusion (9
) is provided around the neck-down core (3) in a ring shape and is integrally molded with the neck-down core (3). Figures 8 and 9 show the shape of the neck-down core (3) in the case of a top feeder.

Basically, the shape and dimensions of the neck hole (6), thin plate-shaped protrusion (5), notch edge (7), and protrusion (9) are almost the same as in the case of a horizontal feeder, but the neck hole (6) It differs from the case of a horizontal riser in that it is located in the center of the riser (1) and symmetrically arranges one U-shaped thin plate-like projection (5) on both sides thereof. The molding material for the neck down core (3) in this example is shell molded river sand, and if other sand is used, it is desirable to use molding sand with good heat retention, such as oil sand or furan sand.

F) Effects of the Invention The neck hole (6) of the present invention has a narrow band shape that is easily broken by impact force, and it has a narrow strip shape that is easily broken by impact force.
The cross-sectional area of 6) was significantly reduced, and the height of the seat (12) remaining in the fractured replica (2) was reduced to almost zero, greatly contributing to the reduction of finishing man-hours. Incidentally, the cross-sectional area of the neck hole (6) is a narrow strip of 6 mm x 80 mm, which corresponds to a 40 mm circular shape in the conventional type. This neck hole (
The ability to significantly reduce the cross-sectional area of 6) is due to the effect of the U-shaped, thin plate-like protrusion (5), which raises and maintains the temperature of the feeder'/g water around the neck hole (6). This is to extend the time and sustain hot water supply. The principle is based on the phenomenon that when a thin-walled protruding core protrudes into the molten metal in a normal product shape, it is surrounded by a large amount of molten metal and solidification around the core is delayed. Liam core causes the molten metal shell around the core of the blind riser to break due to /8i around the core.
A: It occurs because coagulation is delayed. Also, the reason why we were able to set the notch edge (7) on the same plane as the product (8) and reduce the height of the seat (12) to almost zero was due to the neck hole (6 This is because the protrusion (9) with a cross section of 3 mm x 3 mm provided around the outer edge of the groove (9), that is, the product (2), forms a seat surrounded by the groove.

Additionally, the U-shaped, thin plate-like projections (5) serve as reinforcing ribs for the neck down core (3), making it possible to reduce the thickness of the neck down core (3) and improving the feeder effect. Become. It also serves to prevent deformation of the neck down core (3) due to the pressure of the molten metal in the riser.

[Brief explanation of the drawing]

Figures 1 to 5 are explanatory diagrams of the prior art. Figure 1 is a cross-sectional view of how to take a horizontal feeder using a general neck down core, and Figure 2 is a cross-sectional view of how to take a horizontal feeder using a general neck down core. Figure 3 is a cross-sectional view of how to take the top feeder.
-31014) A sectional view of how to take the top feeder using a neck-down core, Fig. 4 7 Fig. 5 is a sectional view showing a state in which a protrusion remains on the neck after the neck-down fracture, Figs. 6 to 9 6 shows an embodiment of the present invention; FIG. 6 is a plan view of a neck down core for a horizontal feeder as seen from the feeder side; FIG. 7 is a cross-sectional view of the neck down core shown in FIG. 6; FIG. 8 is a plan view of the neck-down core for the top feeder as seen from the feeder side, and FIG. 9 is a sectional view taken along line B-El' of the neck-down core of FIG. 8. (1)... riser, (2)... product, (3)...
Neck down core, (4)... riser side, (5)...
・・Thin plate-like protrusion, (6)・・Neck hole (7)・
...Notch edge, (8)...Product side, (9)...
Projection, (12)...Seat, (13)...Protrusion. Patent Applicant Kurimoto Iron Works Co., Ltd. Agent Patent Attorney Jun Aono Figure 1 Figure 2 Figure 4 Figure 2 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] In the neck-down core (3), which is inserted into the boundary between the feeder (1) and the product (2) of the mold and breaks and separates the feeder (1) and product (2) after solidification, the feeder side (4 ) is integrally provided with a thin plate-like projection (5), and a neck hole (
6) is made into a thin strip, and the cutout edge (7) that determines the position of the fracture surface is arranged on the same surface as the product side (8), and the product side (8)
An improved neck down core characterized in that a ring-shaped protrusion (9) is provided around the opening edge of the neck hole (6).