JPH0560640U - Casting core holding device - Google Patents

Abstract

(57) [Abstract] [Purpose] When a ring-shaped salt core is cast into a piston material to form a cooling cavity in the piston material, the cooling cavity having a desired shape without gas defects is formed at a desired portion. The present invention provides a casting core holding device. [Structure] A slit 3a is provided in a core support rod 3, a circular salt core 4 is inserted by a ring-shaped salt core 4, and a T-shaped pin 5 whose tip is elastically clamped in the slit 3a. It is fixed on the core support rod 3. The slit 3a is in communication with the gas vent hole of the mold.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting core holding device, and more particularly to a core holding device suitable for holding in a mold a soluble core that should form a cavity in the head of an engine.

[0002]

[Prior Art]

 As the engine output for vehicles increases, the temperature of the piston rises, and problems such as wear of the piston ring groove, melting of the piston, and seizure easily occur.Therefore, a cooling cavity is formed inside the top of the piston. However, it is generally practiced to pass cooling oil through this cavity.

When forming a cooling cavity inside the piston, an annular soluble core (salt core) made of salt is often cast. In that case, as disclosed in Japanese Utility Model Laid-Open No. 55-143946, for example, a core holding device provided with a plurality of core support rods erected in a mold is used. In that case, after placing the salt core on the core support rod and setting it in the casting mold, the molten aluminum alloy is poured into the cavity to create a piston material that encircles the annular salt core. After that, water is injected through the casting hole of the core support rod to elute the salt core and complete the cooling cavity.

[0004]

[Problems to be solved by the device]

 By the way, since the specific gravity of NaCl, which is a component of the salt core, is smaller than the specific gravity of the aluminum alloy, simply placing the cyclic salt core on the core support rod will cause the salt core to move due to the molten aluminum alloy. Therefore, there is a problem that a cooling cavity cannot be obtained at a desired portion.

Further, even if the cyclic salt core can be fixed on the core support rod by any means, the contact between the molten aluminum alloy having a temperature of 700 ° C. or higher and the salt core causes There was a problem that gas was generated from the core, gas defects were formed in the vicinity of the cooling cavity, and a cooling cavity having a desired shape could not be obtained.

In view of the above-mentioned problems, an object of the present invention is to provide a casting core holding device capable of forming a cavity having a desired shape without gas defects at a desired portion.

[0007]

[Means for Solving the Problems]

 The casting core holding device according to the present invention is such that the core support rod is provided with a slit, and the T-shaped pin inserted into the core is elastically attached to the tip of the T-shaped pin. The core is fixed on a core support rod.

The slit of the core support rod communicates with a gas vent hole provided in the mold.

[0009]

[Action and effect]

 According to the present invention, a slit is provided in the core support rod, and the core is firmly fixed on the core support rod by the T-shaped pin whose tip is elastically held in the slit. It is possible to prevent the core from being displaced due to pouring. In addition, since the gas generated from the core during pouring is discharged to the outside through the slit, it is possible to create a cavity without gas defects in the surroundings. Furthermore, since the T-shaped pin is fixed to the core support rod in such a manner that it is attached to the slit by the elasticity of the slit portion of the core support rod, the T-shaped pin holding force of the slit portion can be maintained even after repeated use. There is also an effect that does not decrease.

[0010]

【Example】

 Hereinafter, an embodiment of a casting core holding device according to the present invention will be described with reference to the drawings.

FIG. 1 is a front cross-sectional view showing a state where an annular salt core is fixed to a core holding device according to an embodiment of the present invention, and FIG. 2 is an enlarged side cross-sectional view of a main part viewed from the direction A of FIG. FIG. 3 is an exploded view of FIG. In FIG. 1, 1 is a center core of a mold, and 2 is a side core fitted around the outer periphery of the center core 1. On the lower flange portion 1a of the center core 1, two core support rods 3 and 3 each having a flat upper end serving as a core mounting surface are erected, and the core support rods 3 and 3 move the side core 2 upward. And penetrates to the upper surface of the side core 2.

As is apparent from FIG. 2, the core support rod 3 has a slit 3a extending downward from the upper end surface along the axis and a core support rod 3 extending laterally from the slit 3a. A gas vent groove 3b that opens to the outer peripheral surface is formed. Further, the side core 2 is formed with a gas vent hole 2a that communicates from the periphery of the outer peripheral surface of the core support rod 3 to the outside.

The annular salt core 4 is placed on the two core support rods 3, 3 and has small-diameter pin insertion holes 4 a, 4 a which are aligned with the axes of the core support rods 3, 3. Has been. Then, as shown in FIG. 3, the T-shaped pins 5 and 5 are inserted from above into these insertion holes 4a and 4a, and the lower end portions of these T-shaped pins 5 and 5 are located below the lower surface of the salt core 4. 2, the slits 3a of the core support rods 3, 3 are pushed and opened in the left-right direction in FIG. Therefore, the lower ends of the T-shaped pins 5 and 5 are sandwiched in the slits 3a and 3a by the elasticity of the portions of the core support rods 3 and 3 where the slits 3a are provided, and the salt core 4 is firmly fixed on the core support rods 3, 3, and each slit 3a communicates with the outside of the mold through the gas vent groove 3b of the core support rod 3 and the gas vent hole 2a of the side core 2.

FIG. 4 is a cross-sectional view showing a state where the salt core 4 attached to the core holding device is cast in the piston material 6 by the aluminum alloy of the piston material. The gas generated from the child 4 is discharged to the outside through the slits 3a and the gas vent grooves 3b of the core support rods 3 and 3 and the gas vent hole 2a of the side core 2. After the piston material 6 is removed from the cores 1 and 2, the sprue part 8 and the riser part 7 are cut from the positions shown by the chain lines. Then, water is injected from the casting holes 9 of the core support rods 3 and 3, the cyclic salt core 4 is eluted, and the T-shaped pins 5 and 5 are discharged, so that the cooling cavity 10 as shown in FIG. Are formed in the piston blank 6.

Next, a method of manufacturing a piston using the casting core holding device according to the present invention will be described.

First, using a NaCl powder having a powder particle size of 100 mesh or less, a cyclic salt core 4 made of a green compact was molded at a green compacting pressure of 1.2 t on / cm ² . Next, this green compact was heated to 120 ° C. at a temperature rising rate of 10 ° C./min and held for 30 minutes to obtain a pre-sintered body. Pin-insertion holes 4a, 4a with a diameter of 1.2 mm were created by drilling at two locations on the diameter of this pre-sintered body, and the temperature was raised to 600 ° C. at a heating rate of 10 ° C./min. And it hold | maintained for 30 minutes and sintered. The cyclic salt core 4 made of the sintered body thus obtained was placed on the core support rods 3 in the mold, and the T-shaped pins 5 and 5 having a diameter of 0.9 mm were respectively inserted into the pin insertion holes. After inserting the lower ends of the T-shaped pins 5 and 5 into the slits 3a of the core support rods 3 and 3 and fixing the ring salt core 4 on the core support rods 3 and 3, , The mold was closed. Next, a molten metal of aluminum alloy (JIS AC8A) having a casting temperature of 770 ° C. was poured from the mold spout to prepare a piston material 6 in which the annular salt core 4 was cast, as shown in FIG. After cutting the sprue part 8 and the riser part 7, water was injected from the casting holes 9 of the core support rods 3 and 3 to elute the cyclic salt core 4 and release the T-shaped pins 5 and 5. The cooling cavity 10 was created.

The piston material 6 obtained by the above method was inspected for residual salt and shape in the cooling cavity 10 by X-ray transmission. As a result, the residual salt of the salt core 4 was found in the cooling cavity 10. In addition, the site and shape of the cooling cavity 10 were good, and no gas defect was observed.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a state in which an annular salt core is fixed to a casting core holding device according to the present invention.

FIG. 2 is an enlarged side cross-sectional view of a main part viewed from the direction A in FIG.

FIG. 3 is an exploded front view of FIG.

FIG. 4 is a front cross-sectional view showing a state in which an annular salt core is cast in a piston material.

FIG. 5 is a front sectional view showing a state in which a cooling cavity is formed in the piston material.

[Explanation of symbols]

 1 Center core 2 Side core 2a Gas vent hole 3 Core support rod 3a Slit 3b Gas vent groove 4 Cylindrical salt core 4a Pin insertion hole 5 T-type pin 6 Piston material 9 Casting hole 10 Cooling cavity

Front page continuation (72) Creator Tadayuki Kuramoto 660, Takaya-cho, Higashihiroshima, Hiroshima Prefecture 1 Mazda Precision Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. A core holding device comprising a core support rod for holding a core in a mold, wherein the core support rod is provided with a slit, and a T-shaped pin inserted into the core is A core holder for casting, characterized in that the core is fixed on the core support rod in such a manner that a tip end thereof is elastically sandwiched in the slit. 2. The casting core holding device according to claim 1, wherein the mold is provided with a gas vent hole communicating with the slit.