JPH0324265Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a shell mold structure for casting shaft objects.

[Conventional technology]

Casting methods using shell molds have the advantage of being able to manufacture products with relatively high precision in complex shapes and are relatively inexpensive, so shell molds are often used in the automobile manufacturing process. This casting method is widely used to manufacture various parts, such as camshafts and crankshafts. By the way, shafts such as camshafts are generally cast by vertical casting using a so-called two-cavity shell mold with cavities formed on both sides of the runner. When casting by vertical casting, it takes time for the molten metal to circulate to the upper part of the cavity, and there is a risk that defects such as poor metal circulation may occur.

Therefore, in conventional shell molds, when vertically casting shaft items, a welcome weir is installed in the middle of the cavity from the middle of the runner, and molten metal with good flow is supplied from this welcome weir to the upper part of the cavity to prevent poor flow. (For example, see Japanese Patent Laid-Open No. 55-42138).

[Problem that the invention attempts to solve]

However, conventional shell molds for casting shafts have had the problem that when shafts are vertically cast and cast, the finished shafts may be bent and deformed.

As a result of intensive research into the causes of bending and deformation in shaft objects, the inventor of the present invention discovered the following. That is, when the casting is solidified and cooled,
Although shrinkage generally occurs, conventional shell molds for casting shafts are provided with a welcome weir that communicates the middle of the runner and the middle part of the cavity as described above. When vertical casting is performed, the castings in the runner, welcoming weir, and cavity contract as the casting cools, and the shrinkage of the casting in the welcoming weir causes tensile force to act on the casting in the cavity. It is thought that bending and deformation occurs in the finished shaft.

In view of this point, this invention aims to provide a shell mold structure for casting shafts that can prevent bending and deformation of shafts.

[Means for solving problems]

Therefore, in the case of a vertically cast shell mold structure, the main pick-up weir is connected to the cavity from the middle of the runner, and the main pick-up weir is extended to the opposite side of the cavity via the core mold to form an auxiliary pick-up weir. It was communicated with.

[Effect]

In this design, as the castings cool, both the castings in the main and auxiliary weirs contract, and the tensile force from the auxiliary weir side and the tensile force on the auxiliary weir side acting on the castings in the cavity are reduced. cancel each other out,
As a result, a shaft with little bending deformation can be cast.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 3 show a shell mold structure for casting shaft objects according to an embodiment of the present invention. In the figure,
Reference numeral 1 designates one main mold, and the main mold 1 is formed with a sprue 2 and a runner 3 in communication with each other in the center, and cavities 4 for casting product parts are provided on both sides of the sprue 2 and the runner 3. The lower end of the runner 3 and the lower ends of the cavities 4 and 5 are connected by a weir 6, and a lift 7 is formed in communication with the upper end of the cavities 4 and 5. 4 and 5 are provided with chillers 12 at appropriate locations.

A core mold 8 is disposed in the middle of the cavity 4 of the main mold 1. In this core mold 8, a main welcoming weir 9 is formed on the runner 3 side, an auxiliary welcoming weir 10 is formed on the opposite side, and a communication passage 11 is formed to communicate the two. It is connected to Route 3.

Further, the other main mold 1 is also formed to have exactly the same structure as described above.

Next, the effects will be explained.

When casting a camshaft using the shell mold of this example, attach the core mold 8 to the main mold 1, align the mating surfaces of the main mold 1, then stand it up, and
Then, the molten metal flows down from the sprue 2 into the runner 3, passes through the weir 6, flows into the cavities 4 and 5, and rises inside the cavities 4 and 5, and the molten metal flows into the cavities 4 and 5. , 5, the molten metal with good flow in the runner 3 reaches the main receiving weir 9.
The molten metal is supplied into the cavities 4 and 5 via the auxiliary pick-up weir 10, and when the molten metal in the cavities 4 and 5 reaches the nozzle 7, it is cooled in this state and a camshaft casting is obtained.

By the way, when a camshaft is cast by vertical casting in this way, there is a concern that the finished camshaft may be bent and deformed due to the pick-up weir as described above, but with the structure of this example, Since the pick-up weir is the main pick-up weir 9 on the side of the runner 3 and the auxiliary pick-up weir 10 on the opposite side, when the casting in the main pick-up weir 9 contracts, the casting in the auxiliary pick-up weir 10 also contracts. The tensile force acting on the castings in cavities 4 and 5 from the main welcoming weir 9 is transferred to the auxiliary welcoming weir 1.
This is offset by the tensile force acting from the zero side, resulting in a camshaft with less bending deformation.

Further, FIGS. 4 to 6 show other embodiments of the present invention. In this embodiment, a recess 13 is formed in the main mold 1, and a communication path 11 between the inner surface of the recess 13 and the outer surface of the core 8 communicates the main reception weir 9 and the auxiliary reception weir 10.
In this way, the communication path 11 between the auxiliary pick-up weir 10 and the main pick-up weir 9 may be formed on the main die 1 side.

In addition, although the above-mentioned embodiment explained the case of casting a camshaft, the present invention can be similarly applied to the case of casting a shaft object other than a camshaft.

[Effect of idea]

As described above, according to the present invention, in a vertically cast shell mold structure, a main reception weir is communicated with the cavity from the middle of the runner, and this main reception weir is extended to the opposite side of the cavity via the core mold. This has the effect of reducing deformation of the shaft, as the tensile force acting from the main weir side as the casting cools is offset by the tensile force acting from the auxiliary weir. There is.

[Brief explanation of the drawing]

Fig. 1 is a front view showing a shell mold structure for casting shaft objects according to an embodiment of the present invention, Fig. 2 is an enlarged view of the main part of the above structure, Fig. 3 is an enlarged sectional view of the main part of the above structure, and Fig. 4 5 is a sectional view of a shell mold structure for casting shaft objects according to another embodiment of the present invention, FIG. 5 is a front view of essential parts of the above structure, and FIG. 6 is a perspective view of a core mold in the above structure. 1... Main mold, 3... Runway, 4, 5... Cavity, 8... Core mold, 9... Main welcoming weir, 10... Auxiliary welcoming weir, 11... Communication passage.

Claims (1)

[Scope of Claim for Utility Model Registration] A shell mold structure for vertical casting of shaft objects, in which a core mold is placed in the middle of the cavity in the main mold, and the core mold has a main pick-up weir on the runner side. , an auxiliary reception weir is formed on the opposite side to communicate with the cavity, the main reception weir communicates with the runner, and the auxiliary reception weir is formed by a communication path formed by the main mold and the core mold. A shell mold structure for casting shaft objects, characterized in that the shell mold structure is connected to the main receiving weir.