JPH0352757A - Method for removing core - Google Patents

Abstract

PURPOSE:To prevent collapse caused by combustion of organic binder in a core print part by hitting air stream to the core print part in core exhausting combustion gas and cooling at the time of burning the organic binder in the core by supplying O2-containing gas. CONSTITUTION:For example, at the time of manufacturing a cylinder block, after filling up molten metal A into cavity in a metallic mold 9, at the time when solidification of raw material 4 is completed, the air blown into the core under pressurizing from a supplying pipe 5 having a value 8. Then, this air is discharged 6 out of the metallic mold 9 in the arrow mark direction in the figure through the core print part 3 while burning the organic binder in the core body 1 through the core print part 2 in core. In this case, after the lapse of about 2 sec after blowing the air from the supplying pipe 5, by sucking the air from gas exhaust hole 6, the air of the atmosphere is sucked in the arrow mark direction from a supplying hole 7 to cool the core print part 3. By this method, the collapse of core print part is prevented and problem of splash of sand from the gas exhaust hole 6 can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a method for removing a core, and more particularly to a method for removing a core after casting in a casting method using a metal mold as a mold.

[Prior art] In a casting method using a core using an organic binder, there is a method of supplying an oxygen-containing gas such as air to the core in order to easily remove the encased core after casting. Are known.

For example, the applicant of the present application has disclosed in Japanese Unexamined Patent Publication No. 141844/1983 that a core using an organic binder that is enclosed in a casting is heated to a temperature higher than the combustion temperature of the organic binder. We proposed a method for removing cores from castings that supplies combustion gas containing oxygen.

Furthermore, in Japanese Patent Application Laid-open No. 1-134161, the present applicant discloses that when an oxygen-containing gas is supplied to the core to burn an organic binder before opening the mold after casting, the core temperature is within a predetermined temperature range. Thus, a core removal method has been proposed in which the oxygen-containing gas is supplied intermittently or the amount of oxygen-containing gas supplied is increased or decreased.

[Problems to be Solved by the Invention] A core for casting consists of a core body and a baseboard. However,
Conventionally, when supplying oxygen-containing gas to the core, the oxygen-containing gas is supplied from at least one of the baseboard parts, which is a fixing means for holding the core body in a predetermined position in the cavity of the mold; Combustion gas was being discharged from the baseboard. However, if oxygen-containing gas is continued to be supplied from the baseboard of the core, not only the organic binder in the core body but also the organic binder in the baseboard of the core that discharges combustion gas will burn. As a result, the baseboard collapses and the sand in the baseboard scatters around the combustion gas outlet, making it necessary to clean the mold. In addition, if the oxygen-containing gas has one supply port and multiple discharge ports, if sand scatters from one discharge port, the oxygen-containing gas will cause a short pass inside the core, causing organic viscosity inside the core. Unevenness occurs in the combustion state of the binder. Furthermore, the combustion gas discharged from the outlet corresponding to the collapsed baseboard contains unburned organic binder, which is heated to about 400°C in contact with the mold wall surface around the outlet. When it is cooled below, it becomes tar-like and adheres to the mold wall, requiring a great deal of effort and time to remove it.

The present invention is intended to solve the above-mentioned problems in the prior art, and its purpose is to reduce the scattering of sand from the baseboard of the core when supplying oxygen-containing gas to the core. It is an object of the present invention to provide a method for removing a core that can prevent a short path of oxygen-containing gas inside the core and prevent tar from adhering to the wall surface of the mold.

[Means for Solving the Problems] In other words, the core removal method of the present invention includes supplying an oxygen-containing gas from at least one baseboard portion of the core consisting of a main body and a baseboard portion before opening the mold after casting. When exhausting combustion gas from other baseboard parts to burn the organic binder in the core body, airflow is applied to the baseboard part of the core from which the combustion gas is discharged to cool the baseboard part. It is characterized by

The airflow applied to the width portion of the core from which combustion gas is discharged may be of any type as long as it can cool the baseboard, and examples thereof include airflow, carbon dioxide, nitrogen, and the like. These can be used alone or in combination. The flow rate is selected appropriately.

Further, as a means for applying airflow to the central portion, a cooling airflow supply port is provided separately from the combustion gas exhaust port. The cooling airflow may be provided by suction or may be pumped. The ψ cooling conditions due to the airflow may be determined in advance through experiments, or may be adjusted manually or automatically by providing a temperature sensor on the baseboard to be cooled or on the mold in the vicinity thereof. Although it is practically convenient to use air as the oxygen-containing gas, other gases may be used as long as they contain oxygen to the extent that the organic binder can be combusted.

[For production]

When the organic binder in the core is burnt, airflow is applied to the width of the core that releases combustion gas to cool the baseboard, which causes the organic binder in the baseboard to collapse due to combustion. can be prevented.

〔Example〕

The invention will be explained in further detail by the following examples. Note that the present invention is not limited to the following examples.

FIG. 1 shows an example in which the method of the present invention is applied to manufacturing a cylinder block. In the figure, numerals 1, 2 and 3 indicate the respective parts of the water jacket core using an organic binder as a binder, ▪ is the core body, and 2 and 3 are the baseboard parts.

After the aluminum molten metal is injected into the cavity of the mold 9 and solidification of the rough material 4 is completed, air is supplied from the supply pipe 5 having the valve 8 at a pressure of 5 Kg/crn and a flow rate of 0.1 Nn.
Blow into the core through the baseboard 2 at a rate of f/min as shown by the arrow in the figure. This air passes through the baseboard part 2 of the core, burns the organic binder in the core body l, passes through the baseboard part 3, and is discharged from the outlet 6 to the outside of the mold 9 as shown by the arrow in the figure. Ru. If air is continued to be blown in this state, the organic binder in the baseboard 3 will also burn, causing the baseboard 3 to collapse and sand to scatter from the discharge port 6.

In order to prevent this, approximately 2 seconds after air is blown in from the supply pipe 5, air is sucked from the exhaust port 6, and air from the atmosphere is sucked in from the supply port 7 as shown by the arrow in the figure, thereby cooling the baseboard portion 3. did. This prevented the baseboard portion 3 from collapsing and solved the problem of sand scattering from the discharge port 6. Note that instead of sniffing air from the supply port 7, for example, a pressure of 5 kg is supplied from the supply port 7.
/crr? Air may be pumped in less than 2 hours. After the organic binder in the core wood l was completely burnt out, the baseboard parts 2 and 3 were removed, and since the core body easily disintegrated, it was removed by sanding.

[Effects of the invention] As described above, the core removal method of the present invention provides a core baseboard that discharges combustion gas when oxygen-containing gas is supplied to the core to burn the organic binder in the core. Since the baseboard is cooled by applying airflow to the baseboard, it is possible to prevent the baseboard from collapsing due to combustion of the organic binder. Therefore, the sand in the baseboard does not scatter into the mold, no sand remains in the mold when the cast rough material is taken out of the mold, and there is no resin attached to the mold wall. Since there is no need to clean the core, it is easy to remove the core, improving work efficiency. Furthermore, a short pass of the oxygen-containing gas inside the core may result in poor firing of the core. Therefore, it is possible to combine the core sand firing process in the conventional casting process, eliminating the need for a separate sand firing process for the purpose of removing core defects, making effective use of factory equipment space and using less energy. shows great effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the core removal method of the present invention. In the figure, l... core body 2.3... baseboard part 4... rough material 5... supply pipe 6... discharge port 7...
Supply port 8... Valve 9... Mold

Claims (1)

[Claims] After casting, before opening the mold, oxygen-containing gas is supplied from at least one baseboard part of the core consisting of a main body and a baseboard part, and combustion gas is discharged from the other baseboard parts to reduce the organic viscosity of the core body. A method for removing cores, which comprises cooling the baseboard part of the core by applying airflow to the baseboard part from which combustion gas is discharged when burning the binder.