JPH0524134U - Ciel Core - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to a shell core used for casting,
The present invention relates to a shell core having improved strength. [Structure] In a core for forming a small hole with a long quartz tube as a core material, a shell layer of resin sand is formed on the outer surface of the quartz tube, and the resin sand is also filled inside the tube of the quartz tube. Harden to give the core strength. For this reason, if the core is used for casting, it is possible to cast a fine hole with high precision, and it is possible to save the trouble of performing a drilling process as a post-treatment. If the particle size of the sand inside the cylinder is made larger than the particle size of the outer shell layer, a core that can be cast with an excellent casting surface and excellent degassing properties will be obtained.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a shell core used for casting and having improved strength.

[0002]

[Prior Art]

 Conventionally, for example, when manufacturing a casting die, there are a method of forming by forging and a method of forming by casting. In forging, as shown in FIG. In precision casting, as shown in FIG. 8, the die 55 is formed by cutting the sprue 55 from the casting formed by the ceramics mold 53 and the sand mold 54 as shown in FIG. When a cooling water channel having a length of, for example, 400 mm or more is provided in the molds 52 and 56, a long gun drill 57 is used for drilling. By the way, the hole drilling by the gun drill 57 has high hole accuracy and good quality, but it requires a lot of processing man-hours and increases the processing cost. Therefore, there is also a forming method in which a long hole is simultaneously punched out by using a core. Has been. For this reason, for example, in Japanese Patent Laid-Open No. 60-6249, since the strength becomes insufficient as the length of the core becomes long, the strength of such a long core is improved and the degassing property is improved. A child is proposed, and the inside of a core molded in a predetermined shape with green sand is reinforced with a core metal such as ceramic, and the core metal is hollow and provided with an appropriate number of gas vent holes.

[0003]

[Problems to be solved by the device]

 However, in the case of the sand core mentioned above, since the raw sand is used as sand, there is a limit to the strength of the core, and especially when a long core is set sideways in the mold and cast. At this time, there was a problem that the core was deformed by the heat of casting the molten metal. For this reason, for example, although a straight long hole was desired to be formed, there was a problem that the hole was bent. On the other hand, if resin sand or the like is used in place of green sand and the sand particles around the core metal are made to bind and harden with resin, a core that is stronger than the sand core can be obtained, but still a certain length or more. There is a problem that the strength becomes insufficient when the length becomes.

[0004]

[Means for Solving the Problems]

 In order to solve such a problem, according to the present invention, a large number of gas vent holes are formed in a hollow cylindrical ceramic core material, and a sand coating layer using a resin as a binder is provided on the outer surface of the core material. In the shell core, the inside of the hollow cylinder of the core material is filled with sand having a particle size equal to or larger than the particle size of the sand of the coating layer on the outer surface of the core material, and the resin is used as a binder Cured. In another embodiment, a rod-shaped member having a diameter slightly smaller than the inner diameter of the hollow cylinder is fitted into the inside of the hollow cylinder of the concentric material with a gap.

[0005]

[Action]

 If the core of a hollow tubular material is filled with sand and hardened, or if it is reinforced with a rod-shaped material that is inserted into the tube, it will have sufficient strength even in the core for long narrow holes. And the collapsibility is not impaired. Therefore, it is possible to save the labor of machining. At this time, the degassing property is improved by increasing the grain size of sand in the cylinder or by providing a gap between the rod-shaped member and the inner cylinder.

[0006]

【Example】

 An embodiment of a shell core of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional view of a shell core showing a first embodiment of the present invention, FIG. 2 is a sectional view of a shell core showing a second embodiment, and FIG. 3 is a perspective view of a core material.

The shell core 1 of the present invention comprises a quartz tube 2 as a core material as shown in FIG. 3, and a shell layer 3 made of resin coated sand or the like is formed on the outer periphery of the quartz tube 2. Is made.

The quartz tube 2 is inexpensive, has a high thermal softening point and a small thermal expansion, and is selected from ceramics materials. For example, a commercially available quartz tube can be used in many laser processing machines. Although the gas vent hole 4 is provided, other ceramic materials such as silicon nitride, alumina, and zirconia may be used.

The quartz tube 2 has a wall thickness of, for example, about 0.5 mm to 1.5 mm, and the gas vent hole 4 has a diameter of about 0.1 mm to 0.5 mm. Of course, the shape of the gas vent hole 4 is not limited to the round shape, and may be a long hole or a deformed hole.

Further, the shell layer 3 is formed by positioning the quartz tube 2 in a core die for core molding (not shown) having a cylindrical cavity having a diameter larger than that of the quartz tube 2, The space formed between the outer peripheral portion of the quartz tube 2 and the inner peripheral portion of the core is filled with resin coated sand, and the coated sand is heated from the inside of the quartz tube 2 to be baked and cured. I am trying. In this way, by heating and firing from the side of the quartz tube 2 having a coefficient of thermal expansion smaller than that of the core type, it is possible to obtain a sound shell layer 3 with less strain.

When the thin shell layer 3 is formed, the quartz tube 2 is heated while being rotated around its axis, and the heated quartz tube 2 is sprinkled with resin coated sand to form the English tube 2. The shell layer 3 may be formed by the attached coated sand. According to this method, there is an effect that it is not necessary to use a core mold for core molding.

After the shell layer 3 is formed on the outer peripheral surface of the quartz tube 2 as described above, the reinforcing resin sand 5 is formed in the cylinder of the English tube 2 in the first embodiment. That is, as shown in FIG. 1, after the resin-coated sand having a larger particle size than the shell layer 3 on the outer surface is filled in the cylinder, it is hardened by warm air or in a furnace at a temperature at which the outer shell layer 3 is not broken and is reinforced. Let's call it resin sand 5.

The particle size of the sand is, for example, that of the sand of the shell layer 3 on the outer surface has a small particle size of about AFS particle size index 70 to 120 to prevent the molten metal from being inserted and to improve the casting surface. At the same time, the reinforcing resin sand 5 inside is made to have a large particle size of AFS particle size of 50 to about 70 to improve the air permeability, but the particle sizes of the sand of the shell layer 3 and the reinforcing resin sand 5 are made the same. Good.

The core 1 having such a configuration is positioned in the casting mold 6 in precision casting as shown in FIG. 6, for example, and the sprue 8 is cut from the cast casting 7 to take out the core 1. If the casting hole 9 is sand-removed, a cooling water channel or the like can be formed extremely easily. At this time, since the required strength is secured, the precision of the casting hole 9 is good, and the degassing property of the gas generated by the thermal decomposition is good, so that the casting quality of the cast product 7 is good. Further, the quartz tube 2 and the core 1 made of resin sand have excellent disintegration property, and the shell sand (organic binder) of the outer shell layer 3 is decomposed by the heat of casting, so post-treatment sand removal is easy. Is.

Further, the core 1 as described above is not limited to the linear shape, but may be a deformed core 11 as shown in FIGS. 4 and 5, for example. That is, in the case of FIG. 4, the thickness of the shell layer 3 on the outer peripheral surface of the quartz tube 2 is changed in the length direction, and in the case of FIGS. 5 (A) and 5 (B), the quartz tube 2 is bent. Then, the shell layer 3 is formed around it. Then, in any case, after that, the reinforcing resin sand 5 is filled in the cylinder and hardened. The bending of the quartz tube 2 can be easily changed by bending it while heating it with a gas burner, for example.

Next, FIG. 2 shows a second embodiment of the present invention. That is, in this case, another thin quartz tube 12 as a rod-shaped member is fitted into the inside of the quartz tube 2 provided with the gas vent hole 4, and the outer peripheral surface of the quartz tube 12 inside and the quartz tube 2 outside A slight gap c is provided between the peripheral surfaces. The gap c is, for example, 0.5 mm to 1.5 mm and acts as a gas vent passage.

Further, the quartz tube 12 inside is not provided with a gas vent hole, and may be constituted by a quartz rod, a ceramic rod, a ceramic pipe or the like in addition to the quartz pipe. Further, the odd-shaped core 11 as shown in FIGS. 4 and 5 may be configured by the double structure of the quartz tubes 2 and 12. Also in this case, after the quartz tube 12 inside is inserted, it is easily bent by heating with a gas burner and bending.

Also in this case, the internal quartz tube 12 serves as a reinforcing material, and the gas generated by thermal decomposition escapes from the gap c and exhibits the same effect as the above-mentioned reinforcing resin sand.

[0019]

[Effect of the device]

 As described above, the shell core of the present invention has a sufficient strength even if it has a long and thin diameter. It can be cast at low cost and easily. Moreover, since the degassing property is good, the casting quality is good, and the disintegration property is also excellent, so that the post-treatment is easy.

[Brief description of drawings]

FIG. 1 is a sectional view of a shell core showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a shell core showing a second embodiment of the present invention.

FIG. 3 is a perspective view of a quartz tube as a core material.

FIG. 4 shows a deformed core, (A) is an overall view, (B) is a sectional view taken along line B-B of (A).

5A and 5B show another embodiment of an irregularly shaped core, in which FIG. 5A shows a curved shape, and FIG. 5B shows a shape combining a straight line and a curved line.

FIG. 6 is an explanatory view showing precision casting by the core of the present invention.

FIG. 7 shows a conventional example, which is formed by forging.

FIG. 8 shows a conventional example, which is formed by casting

[Explanation of symbols]

 (1) Shell core (2) Quartz tube (3) Shell layer (4) Gas vent hole (5) Reinforcing resin sand (12) Quartz tube (c) Gap

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumio Hirai 1-10 Shin-Sayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. A shell core in which a hollow cylindrical ceramic core material is provided with a large number of gas vent holes, and a sand coating layer containing a resin as a binder is provided on the outer surface of the core material. In the inside of the hollow cylinder of the core material, sand having a particle size similar to or larger than the particle size of the sand of the coating layer on the outer surface of the core material is filled and cured using a resin as a binder. Shell core to do. 2. A shell core in which a large number of gas vent holes are bored in a hollow cylindrical ceramic core material, and a sand coating layer containing a resin as a binder is provided on the outer surface of the core material. A shell core, wherein a rod-shaped member having a diameter slightly smaller than the inner diameter of the hollow cylinder is fitted and inserted into the inside of the hollow cylinder of the core material.