JPH05212491A - Adhesive for expendable pattern for casting - Google Patents

Abstract

PURPOSE:To gasify the unburned carbon generated from an adhesive by an oxidizing source at the time of pouring and to prevent the carburization into a casting by incorporating an additive having an oxidizing source into an adhesive. CONSTITUTION:The oxidizing source is incorporated into the adhesive for joining the mating parts of plural expendable patterns which are dividedly formed. The powder of org. matter having oxygen atoms, such as acetal resin, is used as the oxidizing source. The unburned carbon generated from the adhesive is gasified like CO or CO2 by the oxygen atoms in the additive at the time of pouring to prevent the carburization that the carbon infiltrates the casting of a cast steel. If ethylene vinyl acetate is used as the essential component of the adhesive, the adhesion at a low temp. is facilitated by its low m. p.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive for a casting fugitive model, which is used for joining a plurality of divided fusible models which are joined together.

[0002]

2. Description of the Related Art Generally, when forming a disappearing model for casting, which is made of synthetic resin and is decomposed and decomposed by a molten metal, for example, a model having a complicated structure or a model having a hollow portion is formed by a single model. Therefore, it is difficult to join the joints of the dissipative models divided into a plurality of pieces with an adhesive.

When casting a casting by using the extinguishing model for casting formed in this way, if molten metal of cast steel is poured in consideration of the improvement of heat resistance and rigidity of the product,
In the case of an extinguishing model made of expanded polystyrene for casting, unburned carbon generated when the model decomposes during pouring penetrates (carburizes) into the structure of the cast steel, leading to a decrease in strength and deterioration of workability. is there.

Therefore, in place of the above-mentioned extinguishing model for casting made of expanded polystyrene (expanded PS), expanded PS is conventionally used.
There is a means for preventing carburization by the model material itself by using a disappearing model for casting made of foamed polymethylmethacrylate (foamed PMMA) having a different thermal decomposition behavior.

However, although it is possible to prevent carburization by the above-mentioned model material itself, a joint portion of a plurality of fugitive models is formed by, for example, EVA (ethylen-vinylacetate-copolyme).
r) When using a hot melt adhesive,
There was a problem that the hot melt adhesive disappeared during pouring, H (hydrogen) and C (carbon) were generated, and this unburned carbon carburized in the cast steel structure in the same manner as described above.

By the way, Japanese Unexamined Patent Publication No. 3-128145 discloses a technical concept of coating a coating agent on the outer surface of a vanishing model with an additive having an oxidation source such as Fe2 O3 (iron oxide) added thereto. However, even if this technical idea is applied to an adhesive, Fe2 O3 may enter the casting to change the metal composition of the casting, or Fe2 O3 and the main component of the adhesive may be mixed uniformly. There was no problem.

[0007]

SUMMARY OF THE INVENTION The invention according to claim 1 of the present invention provides an adhesive for a fusible model for casting which can prevent a carburizing phenomenon in a cast steel casting caused by the disappearance of the adhesive. And

The invention according to claim 2 of the present invention, in addition to the object of the invention according to claim 1, is an adhesive for a fusible model for casting in which an additive can be uniformly dispersed in the adhesive. For the purpose of providing.

According to the invention described in claim 3 of the present invention, in addition to the object of the invention described in claim 1 or 2, adhesion at low temperature is easy and it is possible to improve model productivity. It is an object of the present invention to provide an adhesive for a disappearable model for casting that can be used.

[0010]

According to a first aspect of the present invention, there is provided an adhesive for a disappearing model for casting, which joins together the joining portions of a plurality of the disappearing models which are formed separately. It is characterized by being a fusible model adhesive for casting containing an additive having an oxidation source.

According to a second aspect of the present invention, in addition to the structure of the first aspect of the invention, the additive is an extinguishing model adhesive for casting, which is an organic substance having an oxygen atom. Characterize.

The invention according to claim 3 of the present invention is, in addition to the constitution of the invention according to claim 1 or claim 2, that the main component of the adhesive is ethylene vinyl acetate. It is characterized by being an agent.

[0013]

According to the invention described in claim 1 of the present invention, since the adhesive contains an additive having an oxidation source, when the adhesive disappears during pouring, the adhesive is generated from the adhesive. The unburned carbon that is used is gasified by the oxidation source in the additive, and there is an effect that the carburization phenomenon in which carbon enters the cast steel casting can be prevented.

According to the invention of claim 2 of the present invention,
In addition to the effect of the invention described in claim 1, since the additive is an organic substance having an oxygen atom, there is an effect that the additive can be uniformly dispersed in the adhesive main component.

According to the invention of claim 3 of the present invention,
In addition to the effect of the invention according to claim 1 or claim 2, since the main component of the adhesive is ethylene vinyl acetate, the low melting point of ethylene vinyl acetate facilitates adhesion at low temperature. There is an effect that the model productivity can be improved.

[0016]

An embodiment of the present invention will be described in detail below. The adhesive of the extinguishing model for casting of this example is an EVA hot melt adhesive composed of EVA base polymer, paraffin wax, tackifier, and others at about 120 ° C. in a stirring container. Melt and add to this EVA hot melt adhesive, acetal resin powder of 100 mesh or less whose molecular structure is shown in FIG. 1 (organic substance having an oxidation source) at a weight ratio of 2: 1 or less, and bond. The above-mentioned EVA (ethylen vinyl acetate copol) as the main component of the agent
ymer, ethylene-vinyl acetate copolymer) -based hot-melt adhesive is stirred so that the acetal resin powder is uniformly mixed.

That is, the components of the adhesive of the disappearing model for casting are listed below. (A) EVA base polymer (B) Paraffin wax (C) Tackifier (D) Others (D) Others (E) Acetal resin powder (however 100 mesh or less) Desired blending weight of acetal resin powder to the EVA hot melt adhesive described above The ratio is 10 to a few percent. That is, if it is 10 wt% or less, a good carburizing prevention effect cannot be obtained, and if it exceeds 30 percent, the acetal resin powders are coagulated with each other to deteriorate the dimensional accuracy of the fugitive model. Here, the above-mentioned acetal resin is an organic substance having a larger amount of oxygen bonded than other organic resins.

If the joining portions of a plurality of dissipative models which have been divided and formed are joined by using the adhesive of the above-mentioned dissipative model for casting, when the adhesive disappears during pouring, the adhesive generated from this adhesive is not generated. Addition of fuel carbon (acetal resin powder)
There is an effect that gasification can be carried out like CO or CO2 by the oxygen atoms in the carbon and the carburizing phenomenon in which carbon enters the cast steel casting can be prevented.

When the above-mentioned acetal resin powder is used as an additive, the same organic additive is mixed with the main component of the organic adhesive.
There is an effect that it can be uniformly dispersed in a VA-based hot melt adhesive.

In addition, since the main component of the above-mentioned adhesive is ethylene vinyl acetate, that is, EVA hot melt, due to the low melting point of this ethylene vinyl acetate,
Adhesion at low temperature is facilitated, and there is an effect that model productivity can be improved.

Next, a method of adhering the adhesive to the vanishing model will be described with reference to FIGS.

The above-mentioned adhesive 2 at about 120 to 140 ° C. is stored in the adhesive tank 1, and an aluminum alloy coating die 3 immersed in the adhesive 2 is provided. The piston rods 5 and 5 of the fluid cylinders 4 and 4 are configured to ascend and descend in the direction of a model holder 6 as a model holding jig above the adhesive agent tank 1.

The vanishing model 7 is attached to the model holder 6 described above.
The recessed portion 6a corresponding to the shape is formed, and the disappearing model 7 is suction-held in the recessed portion 6a, and the mating portion 7a of the disappearing model 7 faces the coating mold 3.

When the adhesive 2 is adhered to the disappearing model 7, the aluminum alloy coating mold 3 is used.
Is dipped in the adhesive 2 and the temperature of the coating mold 3 is adjusted to about 120
The temperature is the same as the temperature of the adhesive 2 of 140 ° C.

At the time when the coating mold 3 reaches the same temperature as the adhesive 2, the fluid cylinders 4 and 4 are driven to raise the coating mold 3 as shown in FIG. Mating part 7
The adhesive 2 is applied to a for about 1.5 seconds, and then the application mold 3 is lowered.

Next, the above-mentioned model holder 6 that suction-holds the disappearing model 7 after application and the model holder 6 that suction-holds the disappearing model 7 for bonding that has been applied by the same method. As shown in FIG. 4, the mating portions 7a, 7a of the upper and lower vanishable models 7, 7 are joined to each other and pressure-bonded for about 30 seconds.

In this way, a plurality of vanishing models 7, 7 are
When joining, the amount of protrusion of adhesive 2 (protrusion height)
A sufficiently disappearable model having an adhesive strength of 0.3 to 1.2 mm can be obtained.

The above method is applied to an exhaust manifold as an automobile exhaust system component to form a vanishing model for the exhaust manifold, and after the vanishing model is subjected to coating and drying treatment. , The extinguishing model whose treatment has been completed is placed in a casting mold, sand filling and vibration energization are performed for molding, and the casting temperature is about 16 while depressurizing the inside of the casting mold.
An exhaust manifold was cast by pouring a molten metal of cast steel containing 0.15 wt% of C (carbon) at 00 ° C. to replace the fugitive model with the molten metal.

Exhaust of the comparative example in which the cast metallographic structure of the model-bonded portion of the exhaust manifold of the present embodiment bonded or cast using the above-mentioned adhesive 2 and the conventional EVA hot-melt adhesive bonded or cast 5 and 6 show the results of photographing the cast metal structure of the model bonded portion of the manifold with an optical microscope at a magnification of 100 times.

In the present embodiment shown in FIG. 5, as a result of using the above-mentioned adhesive 2, the occurrence of carburization is prevented, but FIG.
In the case of the comparative product shown in (1), carburization occurs in which unburned carbon generated during pouring penetrates into the cast steel structure.

Further, as a result of measuring the hardness of the above-mentioned model adhesion part, the one of this embodiment shown in FIG.
ers Hardness) of 166 to 171, whereas the comparative product shown in FIG. 6 has a Vickers hardness of 329 to 214 in the carburized layer and a Vickers hardness of 214 to 172 inside the carburized layer. , Brittle, poor workability.

FIG. 7, FIG. 8 and FIG. 9 show another embodiment of the method of adhering the adhesive to the disappearing model, and as shown in FIG. 8 and FIG. A recessed portion 11 having a semicircular cross section is formed substantially in the center of the portions 11a and 12a.
b, 12b are formed, and these recesses 11b, 12b are formed as shown in FIG.
The upper and lower grip dies 13 shown in FIG.
14 is provided.

As shown in FIG. 7, each of the gripping molds 13 and 14 described above is arranged in a decompression box 15, and a decompression port 16 of the decompression box 15 is connected to a vacuum pump 18 via a decompression line 17.

A pressing rod 19 is connected to the upper gripping mold 13 of the above-mentioned gripping molds 13 and 14, while the lower gripping mold 14 is mounted on a base 20.

Further, an adhesive tank 22 is mounted on the top deck of the decompression box 15 via brackets 21 and 21, and the adhesive tank 22 stores the adhesive 2 and the adhesive. A nozzle 24 is attached to the tip of a hose 23 that is connected to the bottom of the tank 22, and the nozzle 24 is inserted into the mating portion of the recesses 11b and 12b.

When the adhesive 2 is adhered to the disappearing models 11 and 12, the upper and lower gripping dies 13 and 14 are first tightened by the pressure rod 19 at a pressure of about 0.01 kgf / cm ² . Next, pressure is applied to the liquid surface of the adhesive tank 22 to apply the adhesive 2 to the hose 23 and the nozzle 24.
It is injected for about 1 to 2 seconds into the recesses 11b and 12b of the disappearing models 11 and 12 via.

After the adhesive 2 is injected, the pressure applied to the gripping molds 13 and 14 is reduced to 0.005 kgf / cm ² , and at the same time, the vacuum pump 18 is driven to reduce the pressure in the pressure reducing chamber 25 to a level of minus 700 mmHg. For about 2 seconds to advance the recess 1
The adhesive 2 injected between 1b and 12b is permeated and distributed over the entire joint portions 11a and 12a of the upper and lower vanishable models 11 and 12.

Next, after releasing the reduced pressure by the above-mentioned vacuum pump 18, a pressure of about 0.01 kgf / cm ² is applied to the upper and lower gripping molds 13 and 14 again for about 30 seconds via the pressure rod 19 to bond them. Allow Agent 2 to solidify and complete the bond.

According to the above-mentioned bonding method, there is an effect that good bonding can be carried out even when bonding the disappearing model which changes in the three-dimensional direction without the adhesive 2 protruding.

Next, the steps of the entire casting method using the vanishing model will be described with reference to FIG. First step S1
Then, the pre-foaming machine is used to pre-foam expanded PS (polystyrene) or expanded PMMA (polymethylmethacrylate).

Next, in a second step S2, a plurality of model parts and a casting pattern part are molded by a model molding machine using the foamed PS or the foamed PMMA after the pre-foaming is completed.

Next, in a third step S3, the plurality of model parts described above, the model parts and the casting plan part, which are bonded to each other, are bonded by using the above-mentioned adhesive 2 and the print pressure bonding method. The vanishing model is assembled to form, for example, a tree-shaped vanishing model.

Next, in the fourth step S4, the above disappearing model is dipped in a SiO2 type coating material, and a coating material is applied to the entire surface of the disappearing model by a dipping coating method.

Next, in a fifth step S5, the disappearing model after completion of the coating process is conveyed into a drying chamber and subjected to a drying treatment at a low temperature of, for example, about 50 ° C. for about 4 hours.

Next, in the sixth step S6, the fusible model after the completion of the above-mentioned drying process is placed on the bed sand in the flask, and the dry silica sand is sequentially filled from the sand hopper to obtain the fusible model. Buried in dry silica sand.

Next, in a seventh step S7, the flask is vibrated in the three axial directions of the vertical direction, the horizontal direction and the front-back direction by a vibration device such as a vibrator to solidify the dried silica sand.

Next, in the eighth step S8, the molten metal is poured to replace the fugitive model with the molten metal. At this time, since gas is generated during casting and the pressure in the flask becomes high, connect a vacuum pump for decompression to the coupler for decompression and apply decompression to the decompression chamber at the bottom of the casting frame, Hold the pressure properly.

Next, in a ninth step S9, the cast product after casting is taken out and cooled.

Next, in a tenth step S10, the casting is separated into a product part and other parts to obtain a product having a shape corresponding to the model part of the fugitive model.

Here, when the ferritic heat-resistant cast steel member is cast by the above-mentioned method, the composition of the molten metal is such that the weight ratio of C is 0.05 to 0.25% and Si is 0.3 to.
2.0%, Mn 0.2-1.0%, P 0.05% or less, S 0.05% or less, Cr 16-20%, Nb
0.5-1.5%, B 0.02-0.15%, balance F
It is preferable to use a melt of ferritic heat-resistant cast steel composed of e, in which fine Nb carbides are dispersed, and to use a vanishing model made of expanded polymethylmethacrylate.

0.5 to 1.5 wt% as in the above composition
When Nb (niobium) is added, this Nb becomes C (carbon)
To form Nb carbides, suppress the formation of coarse Cr carbides, improve heat resistance, and 0.02-0.1
When 5 wt% of B (boron) is added, this B refines the crystal grains and suppresses the precipitation of coarse Cr carbide that is harmful to thermal fatigue. Therefore, a ferritic heat-resistant cast steel member excellent in fatigue strength and heat resistance. Can be obtained, and also foamed PMMA
When the extinguishing model made of foam is used, the extinguishing model made of foamed PMMA has a high amount of decomposition heat and a high cooling rate of the molten metal, so that an appropriate cooling of the molten metal is achieved and the miniaturization of the carbide is promoted. Since it has no carburizing property, it is possible to manufacture a ferritic heat-resistant cast member that is excellent in heat fatigue resistance and machinability.

Next, the relationship between the sand filling rate and the inclination angle of the fugitive model having a hollow portion when the dry silica sand is filled in the sixth step S6 in FIG. 10 will be described.

FIG. 11 shows a state in which a fusible model 32 corresponding to an exhaust manifold as an automobile exhaust system component is tilted by a predetermined angle θ in a casting frame 31, and FIG. 12 shows the above-mentioned predetermined angle θ = 0 °. , Θ = 10 °, and θ = 20 ° were changed, and the results of actual measurement of the flask vibration time and the filling rate of the sand 33 into the hollow portion are shown.

As is apparent from FIG. 12, when the vanishing model 32 having a hollow portion is tilted at θ = 20 °, it is 3
A sand filling rate of 100% can be obtained in a little less than 0 seconds, the molding time can be significantly shortened, and no excess thickness is generated on the upper side of the inner wall of the hollow portion due to improper sand tightening.

On the contrary, in the case of a horizontal condition of θ = 0 °, 100%
It took about 80 seconds to obtain the sand filling rate, and excess thickness was generated on the upper side of the inner wall of the hollow portion due to poor sand tightening.

As a result, when the inclination angle at the time of sand filling of the fugitive model having a hollow portion is set to θ = 20 ° or more, the molding time can be greatly shortened and a casting having good casting quality can be obtained.

Next, the relationship between the filling method and the deformation of the vanishing model when the dry silica sand 33 is filled in the sixth step S6 in FIG. 10 will be described.

FIG. 13 shows that the length L1 of the casting frame 31 is 200 m.
FIG. 14 shows a state in which a disappearing model (test piece) 34 having a height m of L2 = 100 mm and a wall thickness t = 5 mm is arranged. The vibration acceleration of the flask during the first filling was changed to each value, and the vibration acceleration of the flask during the second filling where sand was filled to the upper end of the flask to vibrate the vibration was changed to each value. The amount of deformation of the test piece 34 at the time is shown.

As a result, the smaller the vibration acceleration of the casting mold during the first filling, the smaller the amount of deformation of the test piece 34, and two stages compared with the method of filling the sand to the upper end of the casting flask at one time. Test piece 3
It was revealed that the amount of deformation with respect to No. 4 was small.

FIG. 15 shows a case where a fusible model corresponding to an exhaust manifold, which will be described later, is arranged in the casting frame, and when the dry silica sand is filled up to the upper side of the exhaust flange portion as the product protruding portion for the first time, In contrast, the relationship between the casting frame vibration time and the sand filling rate in the hollow part when the vibration acceleration in the horizontal direction (horizontal direction and front-back direction) is applied and the numerical value of this vibration acceleration is changed to each value is shown. ..

As is apparent from FIG. 15, the smaller the vibration acceleration at the first time is, the higher the filling rate can be obtained in the hollow portion in a short time. Here, the first vibration acceleration is 1.
The vibration time is about 60 seconds (hollow hole filling rate 90%).
%), And the vibration direction is preferably horizontal (horizontal direction, front-back direction) biaxial direction.

As described above, the first filling was performed without deforming the exhaust flange portion of the fugitive model corresponding to the exhaust manifold, and the above-mentioned weak vibration of 1.25 g, which has a high sand filling property into the hollow port, allowed the dry carbonization to proceed. When the sand is solidified, the larger the acceleration of the second vibration is, the faster the sand is filled into the hollow port portion, and the larger the packing density and the mold strength are. The result is shown in FIG.

That is, in FIG. 16, 1.25 g of biaxial vibration (first vibration) was applied to dry silica sand having an apparent density of 1.49 g / cm ³ before vibration for about 60 seconds, and then dried. Fill silica sand up to the top of the flask and apply 1.5g of triaxial vibration (up / down, left / right, front / rear) (second vibration) for about 40 seconds, giving a total of 100 seconds of vibration. In this case, the filling rate of sand in the hollow part is 100.
%, The apparent density of sand was 1.69 g / cm ³ . When the second vibration is 1.25 g, the apparent density of sand is 1.65 g / cm ³ , and the apparent density of sand decreases. Therefore, it is desirable that the second triaxial vibration acceleration is 1.6 g or more.

When weak vibration is applied during the first sand filling as described above, the sand filling rate in the hollow portion can be achieved in a short time, and the position of the sprue part due to the rising and moving of the disappearing model. It is possible to prevent fluctuations, and by applying a strong vibration of 1.6 g or more during the second sand filling, it is possible to improve the apparent density of sand, the sand filling speed, the filling density and the mold strength. This has an effect of being able to prevent the occurrence of excess thickness due to poor tightening of sand against the upper side of the inner wall of the hollow portion.

17 to 20 show the relationship between the position of the weir and the casting quality when casting a heat-resistant cast steel exhaust manifold.

That is, in FIG. 17, the cast disappearance model 41 is used as an exhaust manifold as an exhaust system part of an automobile through a plurality of short weir part models 43 on the outer surface of the runner part model 42. A total of four product model models 54 ...
Are installed in series.

The runner model 42 described above is shown in FIGS.
As also shown in FIG. 3, the model is formed in a hollow cylindrical hollow portion D having a bottom portion 42a and extends in the vertical direction. The upper end opening 42b of the hollow portion D has a sprue portion and a model positioning portion. Also serve. In addition, in this embodiment, the runner model 4 described above is used.
The height of 2 is set to about 300 mm, the external dimension is set to about 60 mm square, and the internal dimension is set to about 40 mm square, and the runner capacity is set to about 1080 c.
The m ³ and hollow volume are set to about 480 cm ^3, and the ratio of the hollow volume to the runner volume is set to about 44%.

On the outer surface of the above-described runner part model 42, the product part models 44 are connected in series via three weir part models 43, and the positions of the product part models 44 and the weir part models 43 are arranged. The relationship is as shown in FIG. That is, in FIG. 20, 44a is a flange portion connected to the cylinder head of the engine, and 44b, 44c, 44d are exhaust passage portions,
The upper weir part model 43 is located at the flange part 44a at one side upper part of the upper exhaust passage part 44b in the figure, and the central weir part model 43 is at the flange part 44a at one side lower part of the central exhaust path part 44c in the figure. The lower weir model 43 is located at the flange portion 44a at one lower side of the lower exhaust passage portion 44d in the figure.

As is apparent from FIG. 18, the weir model 43 described above has an exhaust flange 45 on the side having a relatively large capacity.
It is located on the side and is formed at a position where the ports are not restrained.

When the weir model 43 is set at such a position, when the molten metal is poured to replace the disappearing model 41,
From the runner model 42 of the hollow shape part D, the molten metal first enters the exhaust flange part 45 having a relatively large capacity through the bottom weir part model 43, and then the central weir part model 43 and the top part. Since it is sequentially replaced through the weir model 43 of No. 4, it is possible to make a non-pressing method, and the circumference of the molten metal becomes substantially uniform.
Since solidification is also substantially uniform as a whole, there is an effect that good casting quality can be secured without causing cracks between the ports.

FIG. 21 shows measured data of the casting temperature and the degree of pressure reduction when casting the cast steel having the above-mentioned composition. In the drawing, the casting temperature is in the range of 1580 to 1620 ° C. When the degree of pressure reduction was in the range of minus 1500 to minus 2000 mmH2O, it was possible to obtain a cast product that had good hot running properties and little seizure. For example, if the degree of reduced pressure is out of the above range, the molten metal will not be able to obtain a good cast product because the molten metal will be injected into the mold coating agent that has been applied and dried on the surface of the disappearing model. Since both are deteriorated, a value within the above range is desirable.

In the correspondence between the constitution of the present invention and the above-mentioned embodiment, the additive having the oxidation source of the present invention corresponds to the acetal resin powder of 100 mesh or less in the embodiment, but the present invention is carried out in the above-mentioned embodiment. The configuration is not limited to the example configuration.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the molecular structure of an acetal resin used as an additive in the adhesive of the fugitive model for casting of the present invention.

FIG. 2 is an explanatory view showing a method of adhering a disappearing cast model.

FIG. 3 is an explanatory diagram when the coating type is raised.

FIG. 4 is an explanatory view showing a joined state of both models.

FIG. 5 is a view showing a metallographic structure of cast steel adhered or cast using the adhesive of the present invention.

FIG. 6 is a view showing a metallographic structure of cast steel that is bonded or cast using a conventional adhesive.

FIG. 7 is an explanatory view showing another embodiment of the method for adhering a disappearing cast model.

FIG. 8 is an explanatory view showing a concave portion for application of an adhesive, which is formed on the disappearing model for casting.

9 is an explanatory view of a state where the recesses shown in FIG. 8 are joined.

FIG. 10 is a process diagram of a casting method using a vanishing model.

FIG. 11 is an explanatory view showing an inclined disposition state of the vanishing model.

FIG. 12 is a characteristic diagram showing the relationship between the flask vibration time and the sand filling rate with respect to the inclination angle of the vanishing model.

FIG. 13 is an explanatory view showing the arrangement of test pieces.

FIG. 14 is a characteristic diagram showing a relationship between a sand filling method and a test piece deformation amount.

FIG. 15 is a characteristic diagram showing the relationship between the flask vibration time and the sand filling rate with respect to the first sand vibration acceleration.

FIG. 16 is a characteristic diagram showing the relationship between the flask vibration time and the sand filling rate with respect to the first and second sand vibration accelerations.

FIG. 17 is a front view showing an example of a disappearing model for casting.

FIG. 18 is a plan view of FIG.

FIG. 19 is a perspective view of an essential part of FIG.

20 is a cross-sectional view taken along the line CC of FIG.

FIG. 21 is a characteristic diagram showing the relationship between the casting temperature and the degree of pressure reduction.

[Explanation of symbols]

 2 ... Adhesive 7 ... Disappearance model 7a ... Mating part

Claims (3)

[Claims] 1. An extinguishing model adhesive for casting, which joins joints of a plurality of divided extinguishing models, wherein the adhesive contains an additive having an oxidation source. Model adhesive. 2. The disappearing model adhesive for casting according to claim 1, wherein the additive is an organic substance having an oxygen atom. 3. The adhesive for a fusible model for casting according to claim 1, wherein the main component of the adhesive is ethylene vinyl acetate.