Tensile testing apparatus and tensile testing method

Abstract

This invention provides a tensile testing apparatus and a tensile testing method for measuring the mechanical properties of a core material mixture during heat curing. [Solution] The present disclosure relates to a tensile testing apparatus for measuring the mechanical properties of a core material mixture during heat curing, comprising: a mold 30 in which the core material mixture is filled into a cavity; a heating mechanism 20 that heats the mold 30 to heat-cur the core material mixture; a tensile mechanism 15 that applies a tensile load to the core material mixture by applying a tensile force to an upper mold 41 or a lower mold 31; an elongation measuring mechanism 22 that measures the elongation of the core material mixture when a tensile load is applied to the core material mixture during heat curing; and a load measuring mechanism 21 that measures the load applied to the core material mixture.

Description

Technical Field

[0001] The present disclosure relates to a tensile test apparatus and a tensile test method.

Background Art

[0002] Patent Document 1 discloses a method for measuring the softening temperature of copper and copper alloys, in which a plurality of samples of copper and copper alloys are obtained, temperature holding annealing treatments are respectively performed on them at different temperatures, and the tensile strength of the samples is measured after air cooling.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the cores used in casting are obtained by heating and curing a raw material mixture in a mold, and it is necessary to have the mechanical properties required for脱模 from the mold. Regarding the mechanical properties of the cores, a design method for predicting without making a prototype using a prediction model has been studied. In order to improve the prediction accuracy of this prediction model, measurement data on the mechanical properties of the core raw material mixture during heating and curing before the completion of the core is required. The present disclosure solves such problems, and provides a tensile test apparatus and a tensile test method for measuring the mechanical properties of a core raw material mixture during heating and curing before the completion of the core.

Means for Solving the Problems

[0005] This disclosure relates to a tensile testing apparatus for measuring the mechanical properties of a core material mixture during heat curing, comprising: a mold having an upper mold and a lower mold, in which a core material mixture is filled into a cavity formed by combining the upper mold and the lower mold; a heating mechanism for heating the mold filled with the core material mixture to heat-cur the core material mixture; a tensioning mechanism for applying a tensile load to the core material mixture filled in the mold by applying a tensile force to the upper mold or the lower mold so that the upper mold and the lower mold separate from each other; an elongation measuring mechanism for measuring the elongation of the core material mixture when a tensile load is applied to the core material mixture by the tensioning mechanism while it is being heat-cured by the heating mechanism; and a load measuring mechanism for measuring the load applied to the core material mixture. This configuration allows for the measurement of the mechanical properties of the core material mixture during heat curing.

[0006] The upper and lower molds are arranged vertically side by side, and one of the upper or lower molds is provided with a projection that protrudes vertically, and the projection is located on the end face facing either the upper or lower mold when the upper and lower molds are assembled, and the other of the upper and lower molds is provided with a hole formed by a hole of a predetermined depth, and the hole is located on the end face facing either the upper or lower mold when the upper and lower molds are assembled, and is located opposite the projection. With this configuration, when a tensile force is applied to the upper or lower mold by the tensioning mechanism, the upper or lower mold can be moved along a vertical line.

[0007] The mold is flat, and the upper and lower molds are each provided with recesses that are concave in the thickness direction, and protrusions that extend in the thickness direction are formed in the recesses. With this configuration, when a tensile force is applied to the upper or lower mold by the tensioning mechanism, the protrusions engage with the core material mixture filled in the cavity, thereby applying a tensile load to the core material mixture.

[0008] The tensile test method of the present disclosure includes the steps of: preparing a core material mixture containing sand, a binder composed of an inorganic material, and a foaming agent; filling the mold with the core material mixture and heating it with the heating mechanism; applying a tensile load to the core material mixture while it is heating and hardening with the tensile mechanism once the core material mixture has hardened; measuring the elongation of the core material mixture with the elongation measuring mechanism and measuring the load applied to the core material mixture with the load measuring mechanism. This configuration allows for the measurement of the mechanical properties of the core material mixture during heat curing. [Effects of the Invention]

[0009] This disclosure provides a tensile testing apparatus and a tensile testing method for measuring the mechanical properties of a core material mixture during heat curing. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of a tensile testing apparatus according to an embodiment. [Figure 2] Figure 1 is a schematic perspective view of the mold for the tensile testing apparatus shown. [Figure 3] Figure 1 is a schematic exploded perspective view of the mold of the tensile testing apparatus shown. [Figure 4] Figure 1 is a schematic partial cross-sectional view of the mold of the tensile testing apparatus shown. [Figure 5] Figure 1 is a schematic diagram showing the shape of the core material mixture filled into the mold of the tensile testing apparatus. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure will be described below with reference to Figures 1 to 5. Figure 1 is a schematic diagram of the tensile testing apparatus according to the embodiment. Figure 2 is a schematic perspective view of the mold of the tensile testing apparatus shown in Figure 1. Figure 3 is a schematic exploded perspective view of the mold of the tensile testing apparatus shown in Figure 1. Figure 4 is a schematic partial cross-sectional view of the mold of the tensile testing apparatus shown in Figure 1. Figure 5 is a schematic diagram showing the shape of the core material mixture filled in the mold of the tensile testing apparatus shown in Figure 1. The Z coordinates shown in Figures 1 to 4 are for convenience in explaining the positional relationships of the components. In Figures 1 to 4, the positive Z-axis direction is vertically downward.

[0012] A tensile testing apparatus according to an embodiment of this disclosure will be described. The tensile testing apparatus 10 shown in Figure 1 comprises a base 11, a crosshead 12, and a pair of support columns 13. A pair of support columns 13, each with a screw thread, are mounted on the upper surface of the base 11 so as to be rotatable about a vertical axis (the Z-axis direction in Figure 1). The crosshead 12 is attached to the upper side of the pair of support columns 13.

[0013] A support member 25 is fixed to the upper surface of the base 11. A lower chuck 16 for gripping the lower mold 31 of the mold 30 is attached to the support member 25. A load sensor 21 is fixed to the lower surface of the crosshead 12. An upper chuck 17 for gripping the upper mold 41 of the mold 30 is attached to the load sensor 21 via a support member 26. The mold 30 is filled with a core material mixture for measuring its mechanical properties.

[0014] Below the base 11, a motor 15 and a pair of reduction gears 14 are positioned as a tensioning mechanism. The motor 15 is connected to a control unit 23, which controls the rotational speed of the motor 15. When the motor 15 rotates in response to a command from the control unit 23, the pair of support columns 13 rotate via the reduction gears 14, causing the crosshead 12 to rise. When the crosshead 12 rises, a tensile force is applied to the upper mold 41 in the vertical upward direction (negative Z-axis direction in Figure 1), causing the lower mold 31 and the upper mold 41 to separate from each other. When the lower mold 31 and the upper mold 41 separate from each other, a tensile load is applied to the core material mixture filled in the mold 30. Note that the pulling force on the upper mold 41 may be applied by a hydraulic actuator or the like instead of the motor 15. Also, instead of applying the pulling force to the upper mold 41, a pulling force may be applied to the lower mold 31 in the vertically downward direction (the positive Z-axis direction in FIG. 1).

[0015] A displacement sensor 22 as an elongation measurement mechanism is attached to the motor 15. When the motor 15 is rotated to apply a tensile load to the nuclear fuel mixture, the displacement sensor 22 measures the amount of rotation of the motor 15 to measure the elongation of the nuclear fuel mixture. Note that the elongation of the nuclear fuel mixture may be measured by attaching a displacement gauge to the mold 30. As a load measurement mechanism, the load sensor 21 measures the load applied to the nuclear fuel mixture when the motor 15 is rotated to apply a tensile load to the nuclear fuel mixture.

[0016] The displacement sensor 22 and the load sensor 21 are connected to the control unit 23. Based on the elongation data input from the displacement sensor 22 and the load data input from the load sensor 21, the control unit 23 obtains a stress-strain curve of the nuclear fuel mixture to which a tensile load has been applied. From this stress-strain curve, mechanical properties such as the tensile strength and yield point of the nuclear fuel mixture can be obtained.

[0017] The tensile testing apparatus 10 is provided with an electric furnace 20 as a heating mechanism. The electric furnace 20 is arranged to surround all components except the control unit 23. When the mold 30 is heated in the electric furnace 20, the nuclear fuel mixture filled in the mold 30 is heat-cured, and the mechanical properties of the nuclear fuel mixture during heat-curing can be measured. Note that instead of the electric furnace 20, a heating mechanism such as a combustion furnace can also be used as long as the mold 30 can be heated. Also, the electric furnace 20 does not have to surround the entire apparatus, and it may be configured to surround only the mold 30.

[0018] Next, the mold 30 filled with the nuclear fuel mixture will be described using FIGS. 2 to 4. A cavity CV is formed in the mold 30, and the nuclear fuel mixture is filled into the cavity CV.

[0019] The mold 30 is in the shape of an elongated flat plate and is formed of an aluminum alloy. A lower chuck 16 is disposed on the lower side in the vertical direction of the mold 30 (the positive Z-axis side in FIG. 2), and an upper chuck 17 is disposed on the upper side in the vertical direction of the mold 30 (the negative Z-axis side in FIG. 2). The mold 30 is divided into a lower mold 31 and an upper mold 41 in the vertical direction (the Z-axis direction in FIG. 2), and the lower mold 31 and the upper mold 41 are arranged side by side in the vertical direction (the Z-axis direction in FIG. 2).

[0020] The upper side in the vertical direction of the lower mold 31 (the negative Z-axis side in FIG. 2) is divided into a first lower mold 32 and a second lower mold 33 in the thickness direction. On the other hand, the lower side in the vertical direction of the lower mold 31 (the positive Z-axis side in FIG. 2) is not divided in the thickness direction and is integrally formed with the first lower mold 32.

[0021] A step portion 31a is provided on the lower side in the vertical direction of the lower mold 31 (the positive Z-axis side in FIG. 2). The step portion 31a is formed by a step provided in the thickness direction of the lower mold 31. By locking a claw portion (not shown) provided at the tip of the lower chuck 16 to the step portion 31a, the lower mold 31 is gripped by the lower chuck 16.

[0022] As shown in FIG. 3, a lower mold recess 34 recessed in the thickness direction is provided in the first lower mold 32. The lower mold recess 34 is formed symmetrically with respect to the central axis in the width direction and is formed up to an end face 35 on the upper side in the vertical direction (the negative Z-axis side in FIG. 3). The lower mold recess 34 is composed of a lower mold narrow portion 34a formed on the upper side in the vertical direction (the negative Z-axis side in FIG. 3) and a lower mold wide portion 34b formed on the lower side in the vertical direction (the positive Z-axis side in FIG. 3). The lower mold wide portion 34b is formed wider than the lower mold narrow portion 34a. A lower mold shoulder 32a is formed in the first lower mold 32. The lower mold shoulder 32a is formed on both outer sides in the width direction of the lower mold narrow portion 34a.

[0023] When the first lower mold 32 and the second lower mold 33 are combined, the lower mold recess 34 forms the first cavity 36. The end face 35 on the vertically upward side (negative Z-axis side in Figure 3) of the first cavity 36 is opened by the recess of the lower mold recess 34, and through this opening it communicates with the second cavity 46 of the upper mold 41, which will be described later.

[0024] A lower mold projection 37 is formed in the center of the lower mold recess 34 in the planar direction. The lower mold projection 37 is formed by a cylindrical protrusion that extends from the bottom of the lower mold recess 34 in the thickness direction of the first lower mold 32. As shown in Figure 2, the height of the lower mold projection 37 is set so that when the first lower mold 32 and the second lower mold 33 are combined, the top surface of the lower mold projection 37 becomes flush with the surface of the second lower mold 33.

[0025] The vertically downward side of the upper mold 41 (the positive Z-axis side in Figure 2) is divided in the thickness direction into a first upper mold 42 and a second upper mold 43. On the other hand, the vertically upward side of the upper mold 41 (the negative Z-axis side in Figure 2) is not divided in the thickness direction and is formed integrally with the first upper mold 42.

[0026] A stepped portion 41a is provided on the vertically upward side of the upper die 41 (the negative Z-axis side in Figure 2). The stepped portion 41a is formed by a step provided in the thickness direction of the upper die 41. The upper die 41 is gripped by the upper chuck 17 by engaging a claw portion (not shown) provided at the tip of the upper chuck 17 with the stepped portion 41a.

[0027] As shown in Figure 3, the first upper mold 42 is provided with an upper mold recess 44 that is recessed in the thickness direction. The upper mold recess 44 is formed symmetrically with respect to the central axis in the width direction and extends to the end face 45 on the vertically downward side (the positive Z-axis side in Figure 3). The upper mold recess 44 is composed of an upper mold narrow portion 44a formed on the vertically downward side (the positive Z-axis side in Figure 3) and an upper mold wide portion 44b formed on the vertically upward side (the negative Z-axis side in Figure 3). The upper mold wide portion 44b is formed to be wider than the upper mold narrow portion 44a. The first upper mold 42 has an upper mold shoulder portion 42a formed thereon. The upper mold shoulder portion 42a is formed on both outer sides in the width direction of the narrow upper mold portion 44a.

[0028] When the first upper mold 42 and the second upper mold 43 are combined, the upper mold recess 44 forms a second cavity 46. The end face 45 of the second cavity 46 on the vertically downward side (positive Z-axis side in Figure 3) is opened by the recess 49 of the upper mold recess 44. When the lower mold 31 and the upper mold 41 are combined, the first cavity 36 and the second cavity 46 are connected via the opening 49 to form a cavity CV.

[0029] An upper mold projection 47 is formed in the central part of the upper mold recess 44 in the planar direction. The upper mold projection 47 is formed by a cylindrical protrusion that extends from the bottom of the upper mold recess 44 in the thickness direction of the first upper mold 42. As shown in Figure 2, the height of the upper mold projection 47 is set so that when the first upper mold 42 and the second upper mold 43 are combined, the top surface of the upper mold projection 47 becomes flush with the surface of the second upper mold 43.

[0030] An injection hole 48 is provided on the vertically downward side of the second upper mold 43 (the positive Z-axis side in Figure 2). The injection hole 48 is formed by a hole that penetrates in the thickness direction. The injection hole 48 is in communication with the upper mold recess 44, and the core material mixture is filled into the second cavity 46 and the first cavity 36 through the injection hole 48. Then, the core material mixture is filled into the cavity CV in the shape shown by the dashed line TP in Figure 3.

[0031] When the motor 15 rotates with the core material mixture filled in the cavity CV, the upper mold 41 is pulled vertically upward (negative Z-axis direction in Figure 3). At the same time, the core material mixture filled in the wide section 44b of the upper mold engages with the protrusion 47 of the upper mold and is pulled vertically upward (negative Z-axis direction in Figure 3). Simultaneously, the core material mixture filled in the wide section 34b of the lower mold engages with the protrusion 37 of the lower mold and is pulled vertically downward (positive Z-axis direction in Figure 3). In this way, when a tensile force is applied to the upper mold 41 by the rotation of the motor 15, which is a tensioning mechanism, a tensile load can be applied to the core material mixture.

[0032] Furthermore, when the motor 15 rotates with the core material mixture filled in the cavity CV, the upper mold 41 is pulled vertically upward (negative Z-axis direction in Figure 3). At this time, the core material mixture filled in the wide section 44b of the upper mold engages with the shoulder section 42a of the upper mold and is pulled vertically upward (negative Z-axis direction in Figure 3). Simultaneously, the core material mixture filled in the wide section 34b of the lower mold engages with the shoulder section 32a of the lower mold and is pulled vertically downward (positive Z-axis direction in Figure 3). In this way, when a tensile force is applied to the upper mold 41 by the rotation of the motor 15, which is a tensioning mechanism, a tensile load can be applied to the core material mixture.

[0033] A mold temperature sensor 61 is attached to the first upper mold 42. The mold temperature sensor 61 is attached to the surface of the first upper mold 42 that is in contact with the second upper mold 43, and measures the temperature of the mold 30. The temperature measured by the mold temperature sensor 61 is output to the control unit 23.

[0034] A mixture temperature sensor 62 is attached to the first upper mold 42. The mixture temperature sensor 62 is attached to the bottom of the upper mold recess 44 and measures the temperature of the core material mixture that is filled into the cavity CV. The temperature measured by the mixture temperature sensor 62 is output to the control unit 23.

[0035] As shown in Figures 3 and 4, the first upper mold 42 is provided with two projections 41b. The projections 41b are provided on the end face 45 of the first upper mold 42 on the vertically downward side (positive Z-axis side in Figure 3), that is, on the end face 45 that faces the lower mold 31 when the lower mold 31 and upper mold 41 are assembled. The projections 41b are formed by cylindrical protrusions that extend vertically downward from the end face 45 (positive Z-axis direction in Figure 3). The two projections 41b are provided so as to sandwich the narrow portion 44a of the upper mold.

[0036] As shown in Figure 4, the first lower mold 32 is provided with two holes 31b. The holes 31b are provided on the end face 35 of the first lower mold 32 on the vertically upward side (the negative Z-axis side in Figure 4), that is, on the end face 35 that faces the upper mold 41 when the lower mold 31 and the upper mold 41 are assembled. The holes 31b are formed by holes of a predetermined depth and are circular in shape when viewed vertically. The two holes 31b are provided in positions that face the two protrusions 41b provided on the first upper mold 42 when the lower mold 31 and the upper mold 41 are assembled.

[0037] As shown in Figure 4, when the lower mold 31 and the upper mold 41 are combined, the projection 41b is fitted into the hole 31b. By providing such a projection 41b and hole 31b, when the motor 15 pulls the upper mold 41 vertically upward (negative Z-axis direction in Figure 4), the upper mold 41 can be moved along the vertical direction (Z-axis direction in Figure 4). In this embodiment, the projection 41b is provided on the first upper mold 42 and the hole 31b is provided on the first lower mold, but the hole may be provided on the first upper mold 42 and the projection on the first lower mold.

[0038] Next, the shape of the core material mixture TP filled into the mold 30 will be explained using Figure 5. This core material mixture TP has the shape of the cavity CV formed in the mold 30. The core material mixture TP filled into the mold 30 is in the shape of an elongated plate and is formed symmetrically with respect to the central axis in the length and width directions. This core material mixture TP consists of wide sections 51 provided at both ends in the longitudinal direction and a narrow section 52 provided in the center in the longitudinal direction. The wide section 51 is formed in a rectangular shape in plan view, except for the connection portion with the narrow section 52. A hole 53 is formed in the center of the wide section 51 in the plan direction. The hole 53 is circular in plan view and is formed as a hole that penetrates in the thickness direction. The dimensions of the wide section 51 are a length (L1) of 50.0 mm, a width (D1) of 100.0 mm, and a radius of 10.0 mm for the hole 53.

[0039] The narrow section 52 is located in the center in the width direction and is formed to be shorter in width than the wide section 51. In other words, the wide section 51 is formed to be wider than the narrow section 52. The dimensions of the narrow section 52 are a length (L2) of 80.0 mm and a width (D2) of 30.0 mm. A rounded corner (R) is formed at the shoulder portion 54 where the wide portion 51 and the narrow portion 52 are connected. The dimension of the rounded corner (R) is a radius of 20.0 mm.

[0040] Next, a tensile test method using the tensile testing apparatus 10 according to the embodiment will be described. The tensile test method includes the steps of preparing a core material mixture, filling a mold with the core material mixture and heating it with a heating mechanism, applying a tensile load to the core material mixture with a tensile mechanism, measuring the elongation of the core material mixture with an elongation measuring mechanism, and measuring the load applied to the core material mixture with a load measuring mechanism.

[0041] First, we will explain the process for preparing the core raw material mixture. A core is a mold made separately from the main mold to form a hollow section in a casting. For example, it is used to form hollow sections such as intake and exhaust ports and water jackets when casting cylinder heads for automobile engines from aluminum.

[0042] The core material includes sand, binder, and foaming agent. Examples of sand include silica sand, alumina sand, olivine sand, chromite sand, zircon sand, and mullite sand, and artificial sand may also be used. Inorganic materials such as water glass, cement, and clay can be used as binders to solidify sand particles. The following section will explain the case where water glass is used as the binder. Foaming agents are used to improve the filling properties of the mold used to form the core. Examples of foaming agents include surfactants such as anionic surfactants, nonionic surfactants, and amphoteric surfactants. These sands, binders, and foaming agents are mixed, and the mixture is stirred using a kneading device to obtain a slurry-like core material mixture with a viscosity within a predetermined range.

[0043] Next, we will explain the process of filling the mold with the core material mixture and heating it using a heating mechanism. The mold 30 is removed from the tensile testing apparatus 10, and the lower mold 31 and upper mold 41 are assembled. Then, the prepared core material mixture is injected into the injection hole 48 provided in the upper mold 41 at a predetermined pressure. In this way, the core material mixture is filled into the cavity CV of the mold 30. Subsequently, the electric furnace 20 is set to a temperature of 300°C, the lower mold 31 of the mold 30 is gripped by the lower chuck 16, and the upper mold 41 is gripped by the upper chuck 17. In this way, the core material mixture filled in the mold 30 is heated in the electric furnace 20, which is the heating mechanism.

[0044] Next, we will explain the process of applying a tensile load to the core material mixture using a tensile mechanism. When the core material mixture heated in the electric furnace 20 reaches a predetermined temperature, hardening occurs due to the dehydration condensation reaction of the water glass contained in the core material mixture. Therefore, when the mixture temperature sensor 62 measures that the temperature of the core material mixture has reached a predetermined temperature (for example, 240°C), the motor 15 is rotated. The rotation of the motor 15 applies a tensile load to the core material mixture filled in the mold 30. Here, the rotation speed of the motor 15 is controlled so that the core material mixture is pulled at a tensile speed of 1 mm / min. In this way, a tensile load is applied to the core material mixture during heat curing by the motor 15, which is a tensile mechanism.

[0045] Next, we will explain the process of measuring the elongation of the core material mixing section using an elongation measuring mechanism and measuring the load applied to the core material mixture using a load measuring mechanism. A tensile load is applied to the core material mixture during heat curing using a tension mechanism, and the elongation of the core material mixture is measured by a displacement sensor 22, which is an elongation measuring mechanism, until the core material mixture breaks. Furthermore, the load applied to the core material mixture is measured by a load sensor 21, which is a load measuring mechanism.

[0046] Based on the elongation data measured by the displacement sensor 22 and the load data measured by the load sensor 21, the control unit 23 obtains a stress-strain curve. From this stress-strain curve, the mechanical properties of the core material mixture during heat curing, such as tensile strength and yield point, can be obtained.

[0047] The tensile testing apparatus of this disclosure comprises a mold into which a core material mixture is filled in a cavity formed by combining an upper mold and a lower mold; a heating mechanism that heats the mold to heat-harden the core material mixture; and a tensile mechanism that applies a tensile force to the upper mold so that the upper mold and the lower mold separate from each other, thereby applying a tensile load to the core material mixture. With these configurations, a tensile load can be applied by the tensile mechanism to the core material mixture that is being heat-hardened by the heating mechanism. Furthermore, the tensile testing apparatus of this disclosure comprises an elongation measuring mechanism for measuring the elongation of a core material mixture subjected to a tensile load when a tensile load is applied to the core material mixture during heat curing by a heating mechanism, and a load measuring mechanism for measuring the load applied to the core material mixture. By having these configurations, the mechanical properties of the core material mixture during heat curing can be measured.

[0048] Furthermore, the upper and lower molds are arranged vertically side by side, and the upper mold is provided with a projection that protrudes vertically. This projection is located on the end face that faces the lower mold when the upper and lower molds are assembled. The lower mold is provided with a hole formed by a hole of a predetermined depth. This hole is located on the end face that faces the upper mold when the upper and lower molds are assembled, and is positioned opposite the projection. With this configuration, when a tensile force is applied to the upper mold by the tensioning mechanism, the upper mold can be moved along a vertical line.

[0049] The mold is flat in shape, and the upper and lower molds are each provided with recesses that are indented in the thickness direction, with protrusions that extend in the thickness direction formed in the recesses. With this configuration, when a tensile force is applied to the upper mold by the tensioning mechanism, the protrusions engage with the core material mixture filled in the cavity, thereby applying a tensile load to the core material mixture.

[0050] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit. [Explanation of Symbols]

[0051] 10. Tensile testing apparatus 15. Motor 20. Electric furnace 21. Load sensor 22. Displacement sensor 30... Mold 31...Lower mold 31b...Hole 34. Lower mold recess 37. Lower mold protrusion 41...upper mold 41b...Protrusion 44. Upper recess 47. Upper convex part CV...cavity

Claims

1. A tensile testing apparatus for measuring the mechanical properties of a core material mixture during heat curing, A mold having an upper mold and a lower mold, wherein a core material mixture is filled into a cavity formed by combining the upper mold and the lower mold, A heating mechanism that heats the mold filled with the core material mixture to heat-harden the core material mixture, A tensioning mechanism that applies a tensile load to the core material mixture filled in the mold by applying a tensile force to the upper mold or the lower mold so that the upper mold and the lower mold move apart from each other, The device comprises an elongation measuring mechanism for measuring the elongation of a core material mixture when a tensile load is applied to the core material mixture while it is being heat-cured by the heating mechanism, and a load measuring mechanism for measuring the load applied to the core material mixture. Tensile testing apparatus.

2. The upper mold and the lower mold are arranged side by side in the vertical direction. Either the upper mold or the lower mold is provided with a projection that protrudes vertically. The aforementioned projection is provided on the end face of the upper mold or the lower mold that faces the upper mold when the upper mold and the lower mold are assembled. The other of the upper mold and the lower mold is provided with a hole formed by a hole of a predetermined depth. The aforementioned hole is provided on the end face of the upper or lower mold that faces the upper or lower mold when the upper and lower molds are assembled, and is located in a position opposite to the projection. The tensile testing apparatus according to claim 1.

3. The mold is in the shape of a flat plate, The upper mold and the lower mold are each provided with recesses that are indented in the thickness direction. A protrusion is formed in the recess that extends in the thickness direction. The tensile testing apparatus according to claim 1.

4. A tensile testing method using the tensile testing apparatus described in any one of claims 1 to 3, A process for producing a core material mixture containing sand, a binder composed of inorganic materials, and a foaming agent, The process involves filling the mold with a core material mixture and heating it with the heating mechanism, Once the core material mixture has hardened, the process involves applying a tensile load to the core material mixture during heat hardening using the tensile mechanism, The process includes measuring the elongation of the core raw material mixture using the elongation measuring mechanism and measuring the load applied to the core raw material mixture using the load measuring mechanism. Tensile testing method.

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