JPS64143B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to casting technology, particularly to core shaping technology.

Conventionally, in the molding of shell cores, as shown in Figure 1, sand is blown into the shell mold firing mold heated and held at 300 to 350°C from the top, the mold is immediately turned over, and the sand is blown into the mold. The mouth side is placed facing downward, and excess sand in the mold cavity and baseboard is removed using a vibrator or the like.

However, in the conventional core manufacturing method using sand removal method by reversing the mold, although it is possible to remove sand sufficiently when sand is removed from a simple shape, the core shape is curved in the sand removal direction. When sand is removed from the mold, sand removal from the mold is poor, and as a result, the core, baseboard, etc. located deep from the sand removal opening of the mold become almost solid. be.

If a core like this, which has insufficient sand removal and is nearly solid, is used for casting, the molten metal will cool down due to the heat capacity of the core, causing shrinkage cavities and poor hot water circulation in the cast product.
There are drawbacks that can cause product defects.

In addition, if a core that is poorly sanded and is in a nearly solid state is used for casting, the core may "burn" during casting.
Moreover, since it is solid, degassing is insufficient, which tends to cause gas defects in cast products.

In addition, even if the core is not solid, if a core with insufficient sand removal is used for casting, a large amount of sand will remain in the cast product after casting. It is necessary to run the sand removal machine many times, or it is necessary to perform a sand firing process to remove sand from the casting, which takes a lot of man-hours and costs high. There is a drawback.

The present invention improves the sand removal properties of baseboards and mold cavity parts that have poor sand removal properties due to core molding using shell molding, and casts using cores molded by this method. The purpose of the present invention is to provide a method for removing sand from a core, which not only produces a cast product of excellent quality and reduces casting defects, but also improves sand removal properties after casting.

This purpose is to create casting cores using shell molds. After heating and holding the mold to the temperature necessary for firing the sand, An unheated mandrel is inserted into the insertion port of the mandrel, sand is blown into the inserted state, and immediately after that, the mandrel is removed from the mold, the mandrel insertion port is made into a hole, and a core shell is fired. After that, place the mold with the hole where the mandrel was removed facing downward,
First, remove the sand from the difficult areas, and then
This is achieved by a method for removing sand from a core, which is characterized in that the mold is relocated with the sand blowing port side facing downward, and excess sand remaining in the mold is removed.

Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 3 shows a core molding die according to an embodiment of the present invention. In this embodiment, the baseboards 2 and 3 and the product cavity straight portion 1a are difficult to remove sand from in the conventional sand removal method using the mold arrangement as shown in FIG.

Therefore, a through hole 6 is provided in the baseboard 2 of the mold 4 from the side of the mold 4, so that the mold 4 has a diameter of 300 mm suitable for firing sand.
As shown in Figure 3, while the temperature is maintained at ~350℃,
An unheated mandrel is inserted into the through hole 6.

Immediately after the sand is blown into the upper surface, but before the sand is baked onto the mandrel 5, the mandrel 5 is removed from the mold 4, resulting in the state shown in FIG.

Thereafter, as shown in Fig. 5, the mold 4 is placed with the hole through which the mandrel 5 has been pulled out facing downward, and by using vibrations such as a vibrator, the conventional sand removal method (Fig. 2) is performed. Now, remove the excess sand from the product cavity 1a and baseboards 2 and 3, which are difficult to remove.
Sand is removed from the opened mandrel insertion hole 6.

Next, as shown in Fig. 6, the mold 4 is repositioned with the sand injection port side facing downward, and the excess sand in the mold cavity is removed using vibrations from a vibrator, etc., as in the conventional method. It is.

As is clear from the above, according to the method of the present invention,
When molding cores using shell molds, sand removal can be improved even in the baseboard and product cavity areas, which have poor sand removal properties, and as a result,
By making the core hollow, not only can the cast product after casting be of stable quality without casting defects such as sink marks, poor hot water circulation, and gas defects, but also it can prevent sand from falling out of the cast product after casting. This has the advantage of reducing core molding cycle time, reducing man-hours, reducing costs, and saving energy, as it eliminates the need for repeated runs through a sand removal machine or sand baking process.

[Brief explanation of the drawing]

FIG. 1 is a front view of a conventional core molding die, FIG. 2 is a diagram showing the conventional core molding die in a state in which sand is removed, and FIG. 3 is a front view of a core molding die according to the present invention. , Figure 4 is a front view showing the state with the mandrel removed;
FIG. 5 is a front view of a mold in which the mandrel extraction hole is disposed at the bottom, and FIG. 6 is a diagram showing the conventional core-making mold in a state in which sand is removed, similar to FIG. 2. 1a...Product cavity straight part, 1b...
...Product cavity curved portion, 2...Baseboard, 3...Baseboard, 4...Mold, 5...Mandrel, 6...Mandrel insertion port.

Claims (1)

[Claims] 1. In making casting cores using shell molds, a mold with a mandrel insertion opening in areas where it is difficult to remove sand, such as the baseboard, is heated to the temperature necessary for firing shell mold resin sand (hereinafter simply referred to as sand). After holding, an unheated mandrel is inserted into the insertion port of the mandrel, sand is blown into the inserted state, and immediately after that, the mandrel is removed from the mold, and the mandrel insertion port is made into a hole to form a core. After firing the shell, place the mold with the hole from which the mandrel was removed facing downward, first remove sand from the difficult areas, then reposition the mold with the sand injection port facing downward, A method for removing sand from a core, which is characterized by removing excess sand remaining in a mold.