JP2020151717A - Ultrathin cast manufacturing method - Google Patents

Abstract

To provide an ultrathin cast manufacturing method capable of manufacturing an ultrathin artistic cast through precision casting.SOLUTION: This ultrathin cast manufacturing method comprises: a passageway attaching step of attaching a passageway to an object to be cast having an ultrathin part; a mounting step of mounting the object to be cast to which the passageway is attached within a mold form; a plaster pouring step of pouring liquid plaster prepared by mixing water and plaster into the mold form and burying the object to be cast; a casting mold forming step of baking the mold form having the object to be cast buried in the liquid plaster and forming a casting mold by baking off the object to be cast; a residue removal step of removing the residue of the baked-off object to be cast from the casting mold through the passageway; a casting step of press-fitting a molten metal through the passageway into the casting mold through vacuum casting; and a take-out step of removing the mold form, and taking out a cast by breaking the casting mold.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing an ultrathin casting, which is produced by precision casting an ultrathin art casting that faithfully imitates a fresh flower or the like.

The precision casting method is described in, for example, Patent Document 1 and has been known for a long time. The precision casting method described in Patent Document 1 uses a mold having a casting space having the same shape as the desired product shape and having a breathability, and non-vacuum the vacuum melting material melted in a vacuum atmosphere. Precision casting is performed by injecting molten metal, which is rapidly redissolved in an atmosphere, from the sprue portion of the mold and vacuum suctioning the peripheral portion of the mold in accordance with this injection.

JP-A-55-153658

The above-mentioned precision casting method that has existed in the past is described as casting thin-walled parts, but is for manufacturing parts having a certain thickness such as a turbine rotor and a turbocharger rotor, for example, 0.1 mm. It is not possible to produce thick ultra-thin art castings by this method, and there has not been a method for producing such ultra-thin art castings in the past.

Therefore, an object of the present invention is to provide a method for producing an ultrathin casting, which can be produced by precision casting an ultrathin art casting.

According to the present invention, a runner mounting step of attaching a runner to a casting object having an ultra-thin portion, a mounting step of mounting a casting target with a runner in a mold, and mixing water and plaster. The combined liquid plaster is poured into this mold, and the casting process is to bury the casting target, and the mold in which the casting target is buried in the liquid plaster is fired, and the casting target is burnt to form a mold. A mold forming step, a residue removing step of removing the residue of the burnt-out casting object from the mold through the above-mentioned runner, and a vacuum casting, a molten metal is press-fitted into the mold through the above-mentioned runner. Provided is a method for manufacturing an ultrathin casting, which comprises a vacuum casting step of performing a casting process and a taking-out step of removing the mold, breaking the mold, and taking out the casting.

For example, a casting target having an extremely thin portion of 0.1 mm thick is fired in a mold embedded in liquid plaster to burn out the casting target to form a mold, and the residue of the burnt casting target is formed. Is removed from the mold, and then the molten metal is press-fitted into the mold by vacuum casting to prepare a casting. As described above, since the object to be cast having the ultra-thin portion is actually cast by vacuum casting, the ultra-thin art casting can be precisely produced.

The vacuum casting process comprises the process of press-fitting molten aluminum, gold, silver, copper or an alloy containing at least one of aluminum, gold, silver and copper into the mold via a runner. Is preferable.

It is also preferable that the object to be cast is a fresh flower.

The mounting process consists of mounting the object to be cast on a base equipped with a sprue so that the sprue communicates with the sprue, and fitting a rod body that melts by firing on the base. It is also preferable that the gypsum pouring step includes a step of pouring liquid gypsum into the cylinder and burying the object to be cast.

It is also preferable that the gypsum pouring step mixes water and gypsum for precision casting at a predetermined ratio to form liquid gypsum.

In this case, the predetermined ratio is more preferably 2.1 to 2.35 for the gypsum for precision casting with respect to 1 water.

It is more preferable that the gypsum pouring step includes a step of mixing water and gypsum for precision casting and then stirring to form a liquid gypsum.

It is preferable that the mold forming step includes a step of gradually raising the temperature in the furnace and maintaining the raised temperature.

In this case, the mold forming step raises the temperature in the furnace to the first temperature to maintain the first temperature for a predetermined time, and then raises the temperature to the second temperature to keep the second temperature for a predetermined time. It is also preferable that the step is to maintain the temperature and then raise the temperature to a third temperature to maintain the third temperature for a predetermined time to form a mold.

In this case, it is more preferable that the first temperature is a temperature near 200 ° C., the second temperature is a temperature near 350 ° C., and the third temperature is a temperature near 700 ° C.

It is also preferable that the residue removing step is a step of sucking and removing the residue through the runner.

It is also preferable that the casting step includes a step of controlling the temperature of the mold to 420 ° C. to 480 ° C.

In this case, it is more preferable that the casting step includes a step of controlling the temperature of the molten metal to a temperature near 700 ° C.

It is also preferable that the taking-out step includes a step of immersing the cast mold in water a plurality of times.

According to the present invention, an art casting having an extremely thin portion as thick as 0.1 mm can be precisely produced.

It is a flowchart which shows the flow | flow of the process in one Embodiment of the manufacturing method of the ultrathin casting by this invention. It is a perspective view of the petals and the calyx part of the fresh flower which is the object of casting in the embodiment of FIG. 1 as seen from the calyx side. It is a perspective view which shows the state which the fresh flower in the embodiment of FIG. 1 is attached to the base for formwork. It is a perspective view which shows the state which attached the cylinder for formwork to the base for formwork in the embodiment of FIG. It is a perspective view which shows the state which the gypsum was poured into the cylinder of FIG. It is a graph which shows the firing time and firing temperature in the embodiment of FIG. It is a perspective view which shows the state which formed the mold by firing in the embodiment of FIG. It is a perspective view which shows the state which the molten metal was poured into the mold in the embodiment of FIG. It is a perspective view which shows the process of taking out a casting in a mold in embodiment of FIG. It is a perspective view which shows the casting of the fresh flower produced in the embodiment of FIG.

FIG. 1 schematically shows a process flow in one embodiment of the method for producing an ultrathin casting of the present invention. In this embodiment, the object to be cast having an extremely thin portion having a thickness of 0.1 mm is one corolla (plural petals and calyx) of a fresh flower.

As shown in the figure, first, a fresh flower to be cast is prepared (step S1). When preparing fresh flowers, it is very important to select fresh flowers that are in good condition. The state of the fresh flower in this case is the "freshness", "tension" and "shape" of the fresh flower. As for "tension", it is best to actually touch the fresh flowers to check. If there is a feeling of resistance when touched, the petals will be thick and the molten metal will flow easily during casting, and when the mold is made of plaster, the corolla will not be easily crushed by the weight of the plaster. It can be shaped into a beautiful shape. Regarding "freshness", fresh flowers are living things, and with the passage of time, water is lost and withered, and the thickness of the petals becomes thin. Therefore, it is necessary to prepare a mold within the passage of time. In particular, it is important to select the purchase source of fresh flowers. Regarding "shape", the success rate of casting decreases when the petal area is large, and the success rate increases when the petal area is small. The number of petals doesn't really matter.

Next, for one of the prepared fresh flowers, a sprue (a way for pouring molten metal) and a sprue (a mouth for pouring molten metal) are attached to the corolla separated from the stem (step S2). FIG. 2 shows the back side (calyx side) of one corolla 10 separated from the stem. As can be seen from the figure, the corolla 10 includes a plurality of petals (petals) 11 and a calyx 12 existing on the back side of the petals 11. A wax rod 14 (see FIG. 3) for forming a cylindrical space serving as a runner is attached to a portion 13 connected to the stem on the back side (calyx side) of the corolla 10. The rod body 14 corresponds to the rod body that is melted by the firing of the present invention, and can be melted and disappeared when the mold is fired later, and a cylindrical space can be created in the mold. Adhesion of the wax rod 14 to the portion 13 is called adhesive wax, and is performed by using a material that becomes sticky and highly adhesive when heated. This adhesive wax also melts and disappears during firing. Before attaching the runner, it is desirable to attach wax to the back side of the outermost petal 11 of the corolla 10 to thicken this portion. As a result, when the mold is formed, the molten metal easily flows in this portion. That is, the outermost petals 11 are often substantially perpendicular to the direction of the applied pressure. For this reason, the molten metal is the most difficult to flow in, so this portion is thickened. Also, if the outer petal portion is thick when it is cast, this portion will be strong and the work will not be easily broken.

FIG. 3 shows a state in which the corolla 10 to which the wax rod 14 is attached is attached to the rubber base 15 having high temperature heat resistance. That is, one end of the rod body 14 attached to the corolla 10 is inserted into the through hole 15a of the base 15, and the rod body 14 is fixed to the through hole 15a using adhesive wax. At that time, the gap between the through hole 15a and the rod body 14 is filled with wax and fixed. On the back side of the base 15, an opening (not shown) of a through hole 15a corresponding to a sprue is provided.

It is important to make the runner as simple as possible so that the applied pressure of the molten metal to the sprue and the corolla of the mold is the highest, and to make the molten metal flow without stress. When there is one corolla 10 as in the present embodiment, as shown in FIG. 3, the corolla 10 is attached so as to be straight to the sprue. In this state, the molten metal is applied at the highest pressure to the corolla portion of the mold. If there are two corollas, attach the tube so that the runner opens in a V-shape with little angle, and configure the molten metal to flow smoothly. Also, the heights of the corolla are different from each other. The reason is that if the heights of the two corollas are the same, too much pressure will be applied to the parts of the same height, causing cracks in the mold from that position and causing burrs, and the mold will crack and melt. This is because there is a risk that metal will flow out. The case of three corollas is the same as the case of two.

Next, as shown in FIG. 4, one end of the stainless steel cylinder 16 is fitted into the groove in the circumferential direction of the base 15 on which the corolla 10 is set to form a mold, and as shown in FIG. Liquid plaster 17 is poured into the mold, and the corolla 10 is buried in the plaster 17 (step S3).

As the plaster 17, it is desirable to use decorative cast plaster (plaster for precision casting). This gypsum for precision casting is different from ordinary gypsum and is a mixture of refractory material and gypsum. Water and this precision casting gypsum are kneaded in a predetermined ratio before use. At that time, the liquid gypsum, which is a mixture of water and precision casting gypsum, is put through a vacuum defoamer to expel the air inside. This is to prevent bubbles from sticking to the corolla and to obtain a beautiful flower texture. The predetermined ratio of water to gypsum for precision casting is preferably 2.1 to 2.35 for gypsum for precision casting with respect to 1 water. In the conventional technique, the amount of gypsum was about 2.4 to 2.5 with respect to 1 water, but according to this, the mold itself becomes strong, but the fluidity of the liquid gypsum deteriorates and it becomes heavy, so that the corolla becomes heavy. It will be crushed. If the amount of gypsum for precision casting is 2.3 to 2.35 with respect to 1 water, the fluidity of the liquid gypsum is improved and the shape of the corolla is not impaired. However, since the amount of gypsum is smaller than that of water, the strength is reduced and the mold cannot withstand vacuum and pressure and may collapse. Therefore, it is desirable to increase the stirring when the gypsum and water are mixed to increase the strength at the time of curing. This utilizes the property of gypsum that the strength increases with stirring. Specifically, when gypsum and water are mixed, the strength is increased by vigorously stirring with a stirrer for about 1 minute to 1 minute and 20 seconds. When the mixture is stirred in this way, the reaction becomes intense, the curing becomes rapid, the curing fluidity deteriorates, and the corolla is crushed. Therefore, the liquid gypsum is quickly poured into the mold.

It is desirable to spray alcohol on the corolla before pouring the liquid plaster into the formwork. Alcohol has the effect of eliminating plaster bubbles, so this spray can copy a beautifully shaped corolla.

Then, the mold in which the plaster 17 is filled and the corolla 10 is embedded in the plaster 17 is fired to prepare a mold (step S4). In this embodiment, an electric kiln capable of accurately controlling the firing time and firing temperature is used for this firing. That is, in order to prevent the occurrence of cracks and over-baking, the firing time and firing temperature are controlled by a special pattern by an electric kiln.

FIG. 6 shows an example of a control pattern of the firing time and the firing temperature in the present embodiment. As shown in the figure, in the present embodiment, the firing temperature is raised from 0 ° C. to 220 ° C., which is the first temperature, over 2 hours, and this first temperature (220 ° C.) is maintained for 2 hours, and then the first temperature (220 ° C.) is maintained. , The temperature is raised to the second temperature of 350 ° C. over 1 hour, and this second temperature (350 ° C.) is maintained for 2 hours. Next, the temperature is raised to a third temperature of 720 ° C. over 4 hours, and the third temperature (720 ° C.) is maintained for 3 hours to complete the firing. The total firing time is 14 hours.

By this firing, the corolla 10 in the mold was burnt out and disappeared, and as shown in FIG. 7, the corolla portion became hollow and the residue (ash) was accumulated in the mold 110 in the mold. Become. In this way, by firing slowly over 14 hours, the mold is completely mineralized and the water of crystallization contained at the molecular level is evaporated by firing firmly without imposing a burden on the mold. It makes it possible to flow high temperature metal. The corolla inside the mold is completely ash.

Next, the ash that is the residue remaining in the mold that has been burnt out in this way is suction-removed through the runner and the sprue (step S5). If a large amount of ash remains, there will be inconveniences such as the molten metal not flowing well during subsequent casting and the formation of holes, so all of them should be removed. In practice, suction is removed through the runner and sprue using a suction machine such as a vacuum cleaner. The suction time depends on the suction strength, but is, for example, 30 seconds when a general vacuum cleaner is used. If the suction time is short, the effect of suction removal is not seen and the success rate of casting decreases, and if the suction time is too long, the vibration of the suction machine is transmitted to the mold and the risk of damaging the inside of the mold increases. In particular, when the inside of the mold is completely burnt out and becomes a hollow state with nothing inside, the inside is easily damaged, so careful handling is required. The texture and structure of the corolla of fresh flowers is very delicate, and in some places a very thin mold is created, so vibration is strictly prohibited and careful suction is required.

Next, molten metal, molten aluminum in the present embodiment, is poured into the mold through a sprue and a runner by vacuum pressure casting (step S6). In the vacuum pressure casting method, the air inside the mold is evacuated, the molten metal is poured in a state close to vacuum, and pressure is instantly applied to the metal by air or an inert gas while the metal does not solidify, and the metal is applied to every corner. It is a technique of press-fitting. In this embodiment, a high-frequency vacuum pressure casting machine YGP-7D2 manufactured by Yoshida Casting Co., Ltd. was used for this vacuum pressure casting. A high frequency vacuum pressure casting machine YG-10D or YG-30S may be used. FIG. 8 shows a corolla casting (casting) 210 cast in the mold in this way.

In vacuum pressure casting, the temperature of the mold and the temperature of the molten metal to be poured are very important. When the molten metal is molten aluminum, the temperature of the mold is in the range of 420 ° C to 480 ° C, and the temperature of the molten metal is about 720 ° C. However, the temperature of the mold is set according to the prototype shape of the corolla. For example, when the petal area is large and it is difficult to press-fit the molten metal, the temperature is set to around 480 ° C. If this temperature relationship is misunderstood, gas will come out from the metal itself and the metal will not enter, or even if it does, the texture of the casting will be rough, and the color will be gray instead of white.

The metal used for such precision casting may be not only aluminum but also gold, silver, copper, other metals, or an alloy containing at least one of these metals. For gold, silver and copper alloys, the casting temperature is 980 ° C to 1100 ° C.

Then, the mold thus cast is taken out from the vacuum pressure casting machine using the sandwiching tool 20, and as shown in FIG. 9, the mold is broken by immersing it in the water 19 filled in the container 18 to break the inside. (Step S7). In general precision casting, when the mold is cast and the sprue is hardened, the mold is put into water while it is hot, and the mold is crushed and broken by the impact of evaporation of water, and the casting inside is taken out. Is done. However, the corolla casting cast in the present embodiment is very delicate with a thickness of 0.1 mm at the thinnest part, so that it may be broken by the impact of evaporation, and it is used in the present embodiment. Since the casting temperature of the aluminum is as low as 720 ° C., even if the aluminum is solidified at the sprue, it may not be solidified inside the mold, and if it is rapidly cooled, the metal is likely to crack or break. Therefore, the mold is not immersed in water at once, but is immersed in water in 3 to 4 times. As a result, when the mold is gradually broken and a part of the casting becomes visible, the dipping operation is stopped, and after a few minutes have passed, the mold is sufficiently cooled and then immersed in water again. When the metal used in precision casting is gold, silver, or a copper alloy, the casting temperature is as high as 980 ° C to 1100 ° C as described above, so if the metal at the sprue is solidified, the metal inside the mold will also solidify. Often. However, since the plaster cannot be sufficiently removed only by dipping, the plaster is carefully removed with a toothbrush or the like, and the casting is taken out. FIG. 10 represents the aluminum casting 310 of the corolla produced in this way. The thinnest part of the aluminum casting 310 is made as thin as 0.1 mm.

All of the above-described embodiments are exemplary and not limited to the present invention, and the present invention can be implemented in various other modifications and modifications. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

10 corolla 11 petals 12 calyx 13 part connected to stem 14 rod body 15 base 15a through hole 16 cylinder body 17 plaster 18 container 19 water 20 pinch 110 mold 210, 310 casting

As the plaster 17, it is desirable to use decorative cast plaster (plaster for precision casting). This gypsum for precision casting is different from ordinary gypsum and is a mixture of refractory material and gypsum. Water and this precision casting gypsum are kneaded in a predetermined ratio before use. At that time, the liquid gypsum, which is a mixture of water and precision casting gypsum, is put through a vacuum defoamer to expel the air inside. This is to prevent bubbles from sticking to the corolla and to obtain a beautiful flower texture. The predetermined ratio of water to gypsum for precision casting is preferably 2.1 to 2.35 for gypsum for precision casting with respect to 1 water. In the conventional technique, the amount of gypsum was about 2.4 to 2.5 with respect to 1 water, but according to this, the mold itself becomes strong, but the fluidity of the liquid gypsum deteriorates and it becomes heavy, so that the corolla becomes heavy. It will be crushed. If the amount of gypsum for precision casting is 2.1 to 2.35 with respect to 1 water, the fluidity of the liquid gypsum is improved and the shape of the corolla is not impaired. However, since the amount of gypsum is smaller than that of water, the strength is reduced and the mold cannot withstand vacuum and pressure and may collapse. Therefore, it is desirable to increase the stirring when the gypsum and water are mixed to increase the strength at the time of curing. This utilizes the property of gypsum that the strength increases with stirring. Specifically, when gypsum and water are mixed, the strength is increased by vigorously stirring with a stirrer for about 1 minute to 1 minute and 20 seconds. When the mixture is stirred in this way, the reaction becomes intense, the curing becomes rapid, the curing fluidity deteriorates, and the corolla is crushed. Therefore, the liquid gypsum is quickly poured into the mold.

Claims (14)

A runner mounting process for attaching a runner to a casting object having an ultra-thin part, a mounting step for mounting the casting target with the runner in a mold, and a liquid plaster that is a mixture of water and gypsum. A plaster pouring step of pouring into the mold and burying the casting target, and firing the mold in which the casting target is buried in the liquid gypsum, and burning the casting target to form a mold. A mold forming step, a residue removing step of removing the residue of the burnt-out casting object from the mold through the runner, and a vacuum casting, a molten metal is placed in the mold via the runner. A method for producing an ultrathin casting, which comprises a vacuum casting step of press-fitting and a taking-out step of removing the mold and breaking the mold to take out the casting. The vacuum casting step is a step of press-fitting a molten aluminum, gold, silver, copper, or an alloy containing at least one of aluminum, gold, silver, and copper into the mold through the runner. The method for producing an ultrathin casting according to claim 1, wherein the ultrathin casting is provided. The method for producing an ultrathin casting according to claim 1 or 2, wherein the object to be cast is a fresh flower. The mounting step includes a step of mounting the casting object on a base provided with a sprue so that the sprue communicates with the sprue, and fitting of a rod body melted by firing on the base. Any one of claims 1 to 3, wherein the gypsum pouring step includes a step of pouring the liquid gypsum into the cylinder and burying the casting object. The method for producing an ultrathin casting according to. The ultrathin casting according to any one of claims 1 to 4, wherein the gypsum pouring step forms the liquid gypsum by mixing water and gypsum for precision casting at a predetermined ratio. Manufacturing method. The method for producing an ultrathin casting according to claim 5, wherein the predetermined ratio is 2.1 to 2.35 of the gypsum for precision casting with respect to 1 water. The ultrathin casting according to claim 5 or 6, wherein the gypsum pouring step includes a step of mixing water and gypsum for precision casting and then stirring to form the liquid gypsum. Manufacturing method of things. The ultrathin casting according to any one of claims 1 to 7, wherein the mold forming step includes a step of gradually raising the temperature in the furnace and maintaining the raised temperature. Manufacturing method of things. The mold forming step raises the temperature in the furnace to a first temperature and maintains the first temperature for a predetermined time, and then raises the temperature to a second temperature and maintains the second temperature for a predetermined time. The method for producing an ultrathin casting according to claim 8, wherein the step is to raise the temperature to a third temperature and maintain the third temperature for a predetermined time to form a mold. The ninth aspect of the present invention is characterized in that the first temperature is a temperature near 200 ° C., the second temperature is a temperature near 350 ° C., and the third temperature is a temperature near 700 ° C. The method for producing an ultrathin casting as described. The method for producing an ultrathin casting according to any one of claims 1 to 10, wherein the residue removing step is a step of sucking and removing the residue through the runner. The method for producing an ultrathin casting according to any one of claims 1 to 11, wherein the casting step includes a step of controlling the temperature of the mold to 420 ° C. to 480 ° C. The method for producing an ultrathin casting according to claim 12, wherein the casting step includes a step of controlling the temperature of the molten metal to a temperature in the vicinity of 700 ° C. The method for producing an ultrathin casting according to any one of claims 1 to 13, wherein the taking-out step includes a step of immersing the mold in water a plurality of times after casting.

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