JP2000102856A - Casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a shrinkage cavity of a finished casting by filling a mold with a molten metal, stopping the metal pouring to a pouring gate of the mold at the point when the metal begins to flow out into a communication gate to a feeder part or into the feeder part, and then pouring a new molten metal to the feeder part after a short time in a casting by a bottom pouring cast process. SOLUTION: It is preferable that a casting frame 2 for housing a sand mold 3 is constituted of a vertical split casting frame, and that the sand mold 3 has a pouring gate and a feeder part 11 so as to pour the molten metal directly to the feeder part 11. A plug 15 is lifted, and the molten metal in a casting ladle 12 is poured into a mold cavity 7 via a pouring funnel 4 and a pouring path 5. When the temperature of a mold 1 exceeds a given value in an output area of the feeder part 11, the metal pouring to the pouring path 5 of the mold 1 is interrupted. The temperature is measured by a non-contact sensor 17 for starting the metal pouring to the feeder part 11. A plug 16 is lifted and the molten metal is poured into the feeder part 11. A core 8 inserted in the mold 1 penetrates through the feeder part 11, and is ended above the maximum pouring level of the feeder part 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for casting a cast part in a mold having one or more feeders.

[0002]

2. Description of the Related Art Conventionally, a casting mold in which casting is performed by push-up casting may be without a casting flask or may have a molding flask composed of two molding flask halves. At that time, the molten metal reaches the mold from below via a pouring port and a pouring passage, or is pressed into a mold from a crucible disposed below the mold via a riser. In the conventional casting method, the molten metal is always poured upward from the bottom into the mold,
Existing gases are displaced. After pouring of the mold cavity, the casting process is terminated when the riser is subsequently poured from the mold cavity and the riser is filled to a certain extent with the molten metal. In that case, the volume shrinkage that occurs during the solidification of the cast part is replenished from the volume of the riser.

[0003]

A disadvantage of this known method, however, is that the material of the riser to be replenished with the shrinkage that occurs during solidification has just the lowest temperature.
The reason for this is that the material flowing into the feeder has already flowed through the entire mold and is therefore already considerably cooled before flowing out into the feeder. For example, when casting a material with a particularly large shrinkage such as aluminum, the shrinkage
It has been found that it is only incompletely replenished by the riser. The present invention has been made in view of the above problems, and an object of the present invention is to provide an essential improvement in shrinkage replenishment and thereby a reduction in shrinkage cavities in a finished cast part. It is to provide a casting method of the type mentioned.

[0004]

In order to achieve the above object, a casting method according to the present invention comprises the steps of pouring a material, pouring a mold cavity of a cast part to be manufactured, and feeding a material from a mold. The problem is solved by being substantially stopped at the point when it begins to flow out to the access port to the section or directly into the feeder section. The riser itself is then filled with fresh hot melt. Thus, the melt is at a higher temperature than the cast component melt. As a result, the contraction of the molded component can be reliably replenished from the riser. According to tests, shrinkage cavities could be largely avoided even during aluminum casting.

Therefore, the pouring of the molten metal into the pouring port is stopped when the molten metal is poured into the mold cavity and starts flowing out to the feeder section or the communication port to the feeder section. This is detected visually or automatically, for example using a sensor that measures the temperature in the region of the outlet of the riser. Next, the feeder section
Filled by fresh hot material. As a result, the critical parts, that is, the parts of the mold that have already been cooled in most cases, are reheated by the hot material of the riser,
Uniform cooling of the cast part is achieved. Since the material in the feeder is hotter than the material in the cast part, there is definitely a sufficiently molten feeder material that can flow back into the resulting cavity of the cast part.

The core charged into the mold cavity preferably extends in its upper region. Thus, this not only penetrates the feeder part, but also ends up somewhat above the pouring level of the feeder part. This configuration likewise ensures good venting of the cast part. At this time, this gas release remains held even when the hot water is poured. Pouring to the pouring funnel and the feeder can be performed, for example, using a casting ladle having two freely closable outlets.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows the mold being poured before the riser, and FIG. 2 shows the injection of the riser of the mold according to FIG. The mold 1 shown in the figure has a casting flask 2 in which a sand mold 3 is formed. The flask is placed vertically and is cast in this state.

The sand mold has a pouring funnel 4 to which a pouring passage 5 is connected. From the pouring passage 5, a partial section 6 connected to the mold cavity 7 of the mold branches off. A core 8 is inserted into the mold cavity 7. These cores have an extension 9 that extends beyond the pouring level 10 of the feeder 11.

The mold 1 is poured by a casting ladle 12 containing molten metal. The casting ladle has two outlets 13, 14 spaced apart from one another. These outlets can be closed by plugs 15,16.

Hereinafter, the operation when these configurations are used will be described. FIG. 1 shows the mold cavity 7 being initially poured with molten metal. For this purpose, the plug 15 is raised and the molten material flows into the pouring funnel 4 via the outlet 13 and subsequently to the mold cavity 7 via the pouring channel 5 and the subsection 6. The molten material slowly rises in the mold until the mold cavity 7 has been poured.

The temperature of the mold is measured at the outlet 19 to the feeder 11 via the heat sensitive sensor 17. As the heat sensitive sensor 17, a sensor for performing non-contact measurement, for example, a laser,
A photodiode or the like can be used. When the temperature exceeds a predetermined temperature, the stopper 15 is closed as shown in FIG.
The stopper 16 is opened. As a result, since the feeder 11 is poured with fresh casting material, the temperature of the feeder becomes higher than the temperature in the communication passage 18 to the mold cavity 7. As a result, the communication channel 18 to the feeder does not solidify, so that the feeder material can always follow the mold cavity 7 for replenishing shrinkage.

[0012]

As is apparent from the above description, the present invention is particularly advantageous for metals and alloys having a large shrinkage, for example, for aluminum and copper alloys. In this way, a casting is obtained which is very uniform and free of shrinkage cavities compared to conventional casting methods. Also, other advantages of the method according to the invention are:
This means that the volume of the feeder can be selected smaller than that of the conventional feeder. This is particularly advantageous when a mold with a flask is used.

[Brief description of the drawings]

FIG. 1 shows a mold that has been poured before a feeder section.

FIG. 2 is a schematic sectional view showing a casting flask used in an embodiment of the present invention, showing the injection of a riser portion of a mold according to FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 2 Casting frame 3 Sand mold 4 Pouring funnel 5 Pouring funnel 6 Partial section 7 Mold cavity 8 Core 9 Extension part 10 Injection level 11 Feeder part 12 Ladle for casting 13 Outlet 14 Outlet 15 Plug 16 Plug 17 Sensor 18 Communication passage 19 Outflow section

Claims (6)

[Claims] In a method of casting a cast part by push-up casting in a mold having one or more feeders, the molten metal is poured into the mold only until the molten metal starts flowing into the feeder. A casting method characterized by pouring into a gate, and then or shortly thereafter, fresh molten metal is poured into a feeder section. 2. The casting method according to claim 1, wherein the step of pouring the mold into the mold is interrupted when the temperature of the mold exceeds a predetermined value in the region of the feeder outlet. 3. A casting flask formed from two casting halves for accommodating a combined sand mold is used as said mold, said sand casting mold having a pouring port and a feeder formed in the sand casting mold. 3. The casting method according to claim 1, wherein the molten metal can be poured into the feeder through a pouring port or directly from the outside. 4. The casting method according to claim 3, wherein said casting part is formed by a vertical split casting flask. 5. The casting method according to claim 1, wherein the start of the pouring step of the feeder is triggered by a sensor for measuring the temperature in a non-contact manner. 6. The core as set forth in claim 1, wherein the core inserted into the mold penetrates the feeder section and ends above the highest pouring level of the feeder section. The casting method according to any one of the above.