Inspection method and inspection device for molding sand

Abstract

The present invention relates to a method and an apparatus for inspecting molding sand. The method for inspecting molding sand according to one embodiment comprises: a step for feeding molding sand into a test tube; a step for compressing the molding sand in the test tube to produce a test piece and measuring the compaction ratio (CB) of the molding sand; and a step for measuring the compressive strength of the test piece by compressing the test piece.

Description

Technical Field

[0001] The present invention relates to a method and a device for inspecting molding sand. Background Art

[0002] As a casting mold for casting, a sand mold obtained by molding molding sand is widely used. For example, a wet sand mold, which is a type of sand mold, is made using molding sand obtained by adding a binder and an additive to silica sand. Usually, the wet sand mold used for casting is temporarily broken up, and a binder and an additive are added to the recovered molding sand to be reused as regenerated sand. The quality of the regenerated molding sand affects the accuracy of the casting, so the quality of the molding sand is managed in the foundry. Specifically, before the sand mold is molded, parameters indicating the characteristics of the molding sand, such as the compaction rate (CB), moisture content, temperature, air permeability, and compression strength, are measured to confirm whether these parameters are within the range of management values.

[0003] As a technique for inspecting molding sand, for example, there is known an apparatus described in Patent Document 1. The apparatus described in Patent Document 1 comprises: a test cylinder; a pressing rod having a pressure plate that moves up and down in the test cylinder; and a working cylinder having a piston rod connected to the pressing rod, and the apparatus positions the pressure plate based on the CB of the molding sand measured in advance, and then supplies molding sand into the test cylinder, compresses the molding sand in the test cylinder to produce a test piece of a predetermined height (50 mm), and measures the compressive strength of the test piece based on the load when the test piece is compressed and broken by a predetermined pressure.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 9-318511

[0005] As described above, in the apparatus described in Patent Document 1, the CB of the molding sand is measured in advance and then the compressive strength is measured in order to prepare a test piece of a predetermined height. That is, in this apparatus, the molding sand sample is put in twice, and the CB and the compressive strength of the molding sand are measured independently for each sample, so the time required to inspect the molding sand becomes long, which is a problem. Summary of the invention

[0006] Therefore, an object of the present disclosure is to shorten the inspection time of molding sand.

[0007] A method for inspecting molding sand according to one embodiment includes: a step of injecting molding sand into a test tube; a step of compressing the molding sand in the test tube to prepare a test piece and measuring the compaction rate (CB) of the molding sand; and a step of compressing the test piece to measure the compressive strength of the test piece.

[0008] According to the present disclosure, it is possible to shorten the time required to inspect molding sand. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1It is a diagram schematically showing the structure of an inspection device according to one embodiment.

[0010] Figure 2 It is a block diagram showing the functional structure of the control device.

[0011] Figure 3 This is a flowchart showing an inspection method according to one embodiment.

[0012] Figure 4 It is a diagram showing the operation of the inspection device.

[0013] Figure 5 It is a diagram showing the operation of the inspection device.

[0014] Figure 6 It is a diagram showing the operation of the inspection device.

[0015] Figure 7 This is a graph showing the relationship between the height of the test piece and the compressive strength.

[0016] Figure 8 It is a graph which shows the relationship between the compression strength before correction and the compression strength after correction.

[0017] Description of Reference Numerals

[0018] 1…inspection device; 11…test cylinder; 12…chute; 13…pressing rod; 15…load sensor; 18…control device; 20…pressing plate; 22, 26…piston rod; 43…injection control unit; 53…CB measuring unit; 55…compression strength measuring unit; S1…molding sand; S2…test piece. DETAILED DESCRIPTION

[0019] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the accompanying drawings, the same elements are marked with the same figure numbers, and repeated descriptions are omitted. For ease of understanding, the accompanying drawings may be partially simplified or exaggerated, and the dimensional ratios and angles are not limited to those recorded in the accompanying drawings. In this specification, the terms "upper", "lower", "left" and "right" are used for convenience based on the states shown in the drawings.

[0020] Figure 1 1 is a diagram schematically showing the structure of an inspection device 1 according to an embodiment. The inspection device 1 inspects the properties of the molding sand used in the molding of the mold. The molding sand is the raw material of the sand mold, and is typically green sand. Green sand is produced by kneading silica sand, a binder, and an additive, for example. As a binder for the green mold, for example, bentonite is used. As an additive, for example, water, coal powder, starch, etc. are used.

[0021] The accuracy of the casting is affected by the properties of the molding sand, and the properties of the molding sand are inspected before the mold is formed. As parameters representing the properties of the molding sand, for example, compaction rate (CB), moisture content, temperature, air permeability, and compressive strength can be cited. The parameters representing the properties of the molding sand are measured and stored by the inspection device 1. When a defective casting occurs, the stored parameters are read and used in activities for suppressing the defective casting.

[0022] CB is the shrinkage rate [%] when the molding sand is compressed with a constant force. Moisture content refers to the amount of free moisture in the molding sand. Compression strength [N / cm 2 ] is the value obtained by dividing the load when the standard test piece is compressed and broken by the cross-sectional area of ​​the standard test piece. The standard test piece is made by the method specified in JIS Z 2601 "Test method for molding sand". Specifically, JIS Z2601 stipulates that the molding sand in the test tube is compacted at a specified pressure to make a standard test piece with a height of 50mm±1mm, and the compressive strength is measured using the standard test piece.

[0023] like Figure 1 As shown, the inspection device 1 includes a test cylinder 11, a chute 12, a pressing rod 13, a first working cylinder 14, a load sensor 15, a second working cylinder 16, a scraper 17 and a control device 18. The test cylinder 11 is, for example, a cylindrical cylinder made of steel, which divides an internal space 11s for accommodating molding sand. The test cylinder 11 is supported by the frame 2 via a supporting member 3. The test cylinder 11 has an upper opening 11a and a lower opening 11b, and extends along an axis Z between the upper opening 11a and the lower opening 11b. Hereinafter, the direction along the axis Z is sometimes referred to as the "axial direction". Typically, the axial direction coincides with the up and down direction. The inner diameter of the test cylinder 11 is constant in the axial direction.

[0024] The chute 12 is provided above the test cylinder 11. The chute 12 guides the molding sand stored in a tank (not shown) to be put into the test cylinder 11. The chute 12 may also have an openable and closable discharge port, and the supply of molding sand to the test cylinder 11 can be switched or stopped by opening and closing the discharge port. The opening and closing of the discharge port is controlled by the control device 18.

[0025] The pressing rod 13 extends along the axis Z, and its upper portion is inserted into the test cylinder 11. A pressure plate 20 is provided at the upper end of the pressing rod 13. The pressure plate 20 is, for example, a disc-shaped plate, and is disposed in the internal space 11s of the test cylinder 11. The lower end of the pressing rod 13 is connected to a piston rod 22 of a first cylinder 14 described later. The pressing rod 13 moves in the axial direction as the piston rod 22 rises and falls.

[0026] The first working cylinder 14 is arranged below the test cylinder 11. The first working cylinder 14 includes a working cylinder body 21, a piston rod 22 and a motor 23. The working cylinder body 21 is arranged on a base 4 arranged at the bottom of the inspection device 1, and supports the piston rod 22 so that it can move forward and backward. The piston rod 22 extends upward from the working cylinder body 21 along the axis Z, and is arranged to be able to rise and fall relative to the working cylinder body 21. The upper end of the piston rod 22 is connected to the lower end of the pressing rod 13. The pressure plate 20 of the pressing rod 13 moves in the axial direction (up and down direction) in the test cylinder 11 as the piston rod 22 rises and falls.

[0027] The motor 23 is, for example, a servo motor that raises and lowers the piston rod 22. The motor 23 includes a motor body 23a and an encoder 23b. The motor body 23a drives the output shaft by power supplied from an external power source. The driving force of the motor body 23a is transmitted to the piston rod 22 via the cylinder body 21, so that the piston rod 22 is raised and lowered along the axis Z. The encoder 23b detects the rotation angle of the output shaft of the motor body 23a. The rotation angle of the output shaft corresponds to the moving distance of the pressing rod 13 in the axial direction. The encoder 23b determines the position of the pressure plate 20 in the axial direction based on the rotation angle of the output shaft.

[0028] The load sensor 15 is disposed between the pressing rod 13 and the piston rod 22. The load sensor 15 is, for example, a load cell, and measures a load applied from the piston rod 22 to the pressing rod 13. The load sensor 15 outputs information indicating the measured load to the control device 18.

[0029] The second cylinder 16 is provided on the side of the test cylinder 11. The second cylinder 16 includes a cylinder body 25, a piston rod 26, and a motor 27. The cylinder body 25 is supported by the frame 2, and supports the piston rod 26 so as to be able to move forward and backward in a direction perpendicular to the axis Z (horizontal direction). The piston rod 26 extends from the cylinder body 25 in the horizontal direction, and is provided so as to be able to move forward and backward relative to the cylinder body 25. The front end of the piston rod 26 is connected to the scraper 17. The scraper 17 moves in the horizontal direction as the piston rod 26 moves forward and backward.

[0030] The motor 27 is, for example, a servo motor that drives the piston rod 26. The motor 27 includes a motor body 27a and an encoder 27b. The motor body 27a drives the output shaft by power supplied from an external power source. The driving force of the motor body 27a is transmitted to the piston rod 26 via the cylinder body 25, so that the piston rod 26 moves in the horizontal direction. The encoder 27b detects the rotation angle of the output shaft of the motor body 27a. The rotation angle of the output shaft corresponds to the horizontal movement distance of the scraper 17. The encoder 27b determines the horizontal position of the scraper 17 based on the rotation angle of the output shaft.

[0031] The scraper 17 is connected to the piston rod 26 of the second cylinder 16. The scraper 17 has a closing surface 17a for closing the upper opening 11a of the test cylinder 11 and a measuring surface 17b arranged above the closing surface 17a. The closing surface 17a and the measuring surface 17b are planes perpendicular to the axis Z and face downward. The closing surface 17a is arranged at a height position substantially the same as the upper opening 11a of the test cylinder 11 in the axial direction. The distance between the closing surface 17a and the measuring surface 17b in the axial direction is set higher than the target height of the test piece.

[0032] The scraper 17 moves in the horizontal direction along with the advance and retreat of the piston rod 26. Specifically, the scraper 17 can move between a closed position where the closing surface 17a closes the upper opening 11a of the test cylinder 11, a retreat position where the scraper 17 is offset from the supply path of the molding sand from the chute 12 to the test cylinder 11, and a measuring position where the measuring surface 17b is arranged above the upper opening 11a of the test cylinder 11.

[0033] The inspection device 1 may also include a rail 36 and a slider 37. The rail 36 is fixed to the upper portion of the frame 2 and extends parallel to the piston rod 26. The slider 37 is slidably mounted on the rail 36. The slider 37 is connected to the scraper 17 by bolts or the like. When the piston rod 26 moves forward or backward, the slider 37 slides along the rail 36 to guide the scraper 17 in the horizontal direction.

[0034] In addition, the inspection device 1 is provided with various sensors for measuring the properties of the molding sand. Specifically, the inspection device 1 is provided with a temperature sensor 31, a moisture sensor 32, and a pressure sensor 33. The temperature sensor 31 is arranged above the test cylinder 11, and measures the temperature of the molding sand. The moisture sensor 32 is provided in the test cylinder 11, and measures the moisture content of the molding sand contained in the internal space 11s of the test cylinder 11. The pressure sensor 33 is provided in the test cylinder 11, and measures the pressure of the internal space 11s of the test cylinder 11.

[0035] The control device 18 is a computer including a processor, a storage unit, an input device, a display device, etc., and controls the overall operation of the inspection device 1. The storage unit of the control device 18 stores a control program for controlling various processes executed by the control device 18 through the processor. The control device 18 is connected to the chute 12, the first cylinder 14, the load sensor 15, the second cylinder 16, the encoders 23b and 27b, the temperature sensor 31, the moisture sensor 32, and the pressure sensor 33 so as to be communicable.

[0036] The control device 18 sends control signals to the chute 12, the first cylinder 14, and the second cylinder 16 to control the operations of the chute 12, the first cylinder 14, and the second cylinder 16. In addition, the control device 18 receives the measured values ​​of the load sensor 15, the temperature sensor 31, the moisture sensor 32, and the pressure sensor 33 to measure parameters representing the characteristics of the molding sand.

[0037] Figure 2 is a block diagram showing the functional structure of the control device 18. Figure 2 As shown, the control device 18 includes a control unit 40 and a measuring unit 50 as functional components. The control unit 40 includes a predicted value acquisition unit 41 , an input amount determination unit 42 , an input control unit 43 , a first cylinder control unit 44 , and a second cylinder control unit 45 .

[0038] The predicted value acquisition unit 41 acquires the predicted value of the CB of the molding sand. A skilled operator can sometimes predict the CB of the molding sand based on the appearance, feel, weather, etc. of the molding sand. In this case, the predicted value acquisition unit 41 acquires, for example, the predicted value of the CB input by the operator via the input device. In addition, the predicted value acquisition unit 41 may also acquire the CB of the molding sand measured in the past as the predicted value of the CB. For example, the CB of the molding sand measured in the past at each processing line of the molding sand may be stored in the storage unit, and the predicted value acquisition unit 41 reads the CB of the corresponding processing line from the storage unit and acquires it as the predicted value of the CB.

[0039] The input amount determination unit 42 determines the amount of molding sand that should be input into the test cylinder 11 in order to produce a test piece of a target height (e.g., 50 mm). The amount of molding sand that should be input into the test cylinder 11 is calculated based on the target height of the test piece to be produced and the predicted value of CB. The amount of molding sand that should be input into the test cylinder 11 is represented by the height of the molding sand before compression. The height of the molding sand before compression refers to the height of the molding sand in the test cylinder 11 before compression based on the height of the pressure plate 20. In the following description, the height of the molding sand before compression is sometimes referred to as the "sand filling height." For example, when the target height of the test piece is set to Ht and the predicted value of CB is set to CBp, the sand filling height H1 of the test cylinder 11 is calculated as shown in the following formula (1).

[0040] H1=100×Ht / (100-CBp)…(1)

[0041] The sand filling height H1 obtained by formula (1) is equivalent to the amount of molding sand that should be put into the test tube 11 in order to make a test piece of target height Ht. As described above, the lower the predicted value CBp of CB, the lower the sand filling height H1, and the higher the predicted value CBp of CB, the higher the sand filling height H1. In addition, the predicted value acquisition unit 41 can also obtain the predicted value of the amount of molding sand that should be put into the test tube 11 in order to make a test piece of target height Ht from the operator. In the case where the predicted value of the amount of molding sand is input by the operator, the predicted value of CB can be determined as the amount of molding sand that should be put into the test tube 11 without obtaining the predicted value of CB.

[0042] The injection control unit 43 controls the chute 12 to supply the molding sand into the test cylinder 11. For example, the injection control unit 43 controls the chute 12 so that the molding sand of the amount determined by the injection amount determination unit 42 is injected into the test cylinder 11.

[0043] The first cylinder control unit 44 controls the motor 23 of the first cylinder 14 to adjust the stroke (the ascending distance or descending distance) of the piston rod 22. The position of the pressure plate 20 in the axial direction is adjusted according to the stroke of the piston rod 22. The position of the pressure plate 20 in the axial direction is determined based on the output of the encoder 23b. That is, the first cylinder control unit 44 controls the position of the pressure plate 20 in the up-down direction based on the output of the encoder 23b. The depth of the test cylinder 11, that is, the sand filling height H1, changes according to the position of the pressure plate in the axial direction.

[0044] The second cylinder control unit 45 controls the motor 27 of the second cylinder 16 to adjust the stroke of the piston rod 26. The horizontal position of the scraper 17 is adjusted according to the stroke of the piston rod 26. The horizontal position of the scraper 17 is determined based on the output of the encoder 27b. That is, the second cylinder control unit 45 controls the horizontal position of the scraper 17 based on the output of the encoder 27b.

[0045] The measuring unit 50 includes a temperature measuring unit 51, a moisture content measuring unit 52, a CB measuring unit 53, an air permeability measuring unit 54, a compressive strength measuring unit 55, and a compressive strength correcting unit 56. The temperature measuring unit 51 measures the temperature of the molding sand based on the output value of the temperature sensor 31. The moisture content measuring unit 52 measures the moisture content of the molding sand based on the output value of the moisture sensor 32.

[0046] The CB measuring unit 53 measures the CB of the molding sand based on the difference between the height of the molding sand in the test cylinder 11 before compression and the height of the molding sand in the test cylinder 11 after compression. The height of the molding sand before compression refers to the surface height of the molding sand in the test cylinder 11 based on the height of the pressurizing plate 20, that is, the filling height of the sand. The height of the molding sand after compression refers to the height of the test piece produced by compressing the molding sand. In addition, the height of the molding sand in the test cylinder 11 is determined based on the stroke amount of the first working cylinder 14 determined based on the output of the encoder 23b.

[0047] The air permeability measuring unit 54 measures the air permeability of the test piece. Specifically, the air permeability measuring unit 54 supplies air from the air source 35 into the test cylinder 11 so as to pass through the test piece, and measures the air permeability of the test piece based on the flow rate of the air when the pressure in the test cylinder 11 is constant.

[0048] The compression strength measuring unit 55 measures the compression strength of the test piece. Specifically, the compression strength measuring unit 55 acquires the load when the test piece is compressed and broken from the load sensor 15, and measures the compression strength of the test piece based on the load.

[0049] The compressive strength correction unit 56 corrects the compressive strength based on the difference between the target height of the test piece and the measured value of the height of the test piece. For example, the compressive strength correction unit 56 corrects the measured compressive strength in a way that increases when the measured value of the height of the test piece is greater than the target height, and corrects the measured compressive strength in a way that decreases when the measured value of the height of the test piece is less than the target height. The measuring unit 50 stores the measured molding sand temperature, moisture content, CB, air permeability, and corrected compressive strength in the storage unit, and displays them on the display device 60.

[0050] Hereinafter, a method of inspecting molding sand using the inspection device 1 will be described. Figure 3 1 is a flowchart showing a method for inspecting molding sand according to one embodiment. In this inspection method, CB and compressive strength are measured based on the molding sand S1 put into the test tube 11. Figure 3 Each step is executed by the control device 18 controlling each element of the inspection device 1.

[0051] like Figure 3 As shown, first, the predicted value acquisition unit 41 of the control device 18 acquires the predicted value of CB of the molding sand S1 (step ST1). The predicted value of CB is input to the inspection device 1 by an operator, for example. In addition, the predicted value acquisition unit 41 may read the CB of the molding sand S1 measured in the past from the storage unit as the predicted value of CB.

[0052] Next, the input amount determination unit 42 determines the amount of the molding sand S1 to be input into the test tube 11 in order to produce the test piece S2 of the target height (e.g., 50 mm) (step ST2). For example, the input amount determination unit 42 substitutes the target height of the test piece S2 and the predicted value of CB into the above formula (1) to obtain the sand filling height H1. As described above, the diameter of the test tube 11 is constant in the axial direction, so the sand filling height H1 corresponds to the amount of the molding sand S1 to be input into the test tube 11 in order to produce the test piece S2 of the target height.

[0053] Next, if Figure 4 As shown in (a) of FIG. 1 , the first cylinder control unit 44 controls the stroke of the first cylinder 14 to adjust the position of the pressure plate 20 so that the distance between the pressure plate 20 and the upper opening 11a of the test cylinder 11 becomes the sand filling height H1 obtained in step ST2 (step ST3). Figure 4 As shown in (b), the second cylinder control unit 45 controls the second cylinder 16 to place the scraper 17 in the retracted position. Then, the input control unit 43 controls the chute 12 to input the molding sand S1 into the test cylinder 11 (step ST4). At this time, the chute 12 inputs the molding sand S1 into the test cylinder 11 in such a manner that the molding sand S1 overflows from the upper opening 11a of the test cylinder 11.

[0054] Next, the temperature of the molding sand S1 is measured by the temperature sensor 31 (step ST5 ). The temperature measuring unit 51 acquires information indicating the temperature of the molding sand S1 from the temperature sensor 31 and stores the information.

[0055] Next, if Figure 4 As shown in (c), the second cylinder control unit 45 advances the piston rod 26 of the second cylinder 16 to place the scraper 17 in the closed position. The scraper 17 moves from the retracted position to the closed position, thereby removing a portion of the excess molding sand S1 overflowing from the test cylinder 11. By placing the scraper 17 in the closed position, the upper opening 11a of the test cylinder 11 is covered and closed by the closed surface 17a of the scraper 17. As a result, the height of the molding sand S1 before compression is consistent with the sand filling height H1.

[0056] Next, if Figure 5 As shown in (a), the first cylinder control unit 44 raises the piston rod 22 of the first cylinder 14, and applies a predetermined pressure to the molding sand S1 from the pressure plate 20. As a result, the molding sand S1 is compressed between the pressure plate 20 and the closed surface 17a of the scraper 17, and a test piece S2 of the molding sand S1 is prepared (step ST6). At this time, the pressure applied to the molding sand S1 from the pressure plate 20 is measured by the load sensor 15, and is fed back to become a predetermined pressure.

[0057] Next, the CB measuring unit 53 measures the height H2 of the test piece S2 (step ST7). The height H2 of the test piece is obtained based on the position of the pressurizing plate 20 determined based on the output of the encoder 23b. The height H2 of the test piece measured in step ST7 is a measured value of the height of the test piece S2. Next, the CB measuring unit 53 calculates the CB of the molding sand S1 (step ST8). The CB of the molding sand S1 is obtained based on the difference between the height of the molding sand S1 before compression (i.e., the sand filling height H1) and the height H2 of the test piece S2 produced by compressing the molding sand S1. Specifically, CB [%] is obtained according to the following formula (2).

[0058] CB=(H1-H2) / H1×100…(2)

[0059] As described above, the CB measuring unit 53 compresses the molding sand S1 in the test tube 11 to prepare the test piece S2 and measures the CB of the molding sand S1. The CB of the molding sand S1 measured by the formula (2) is the measured value of the CB.

[0060] Next, the moisture sensor 32 measures the moisture content of the test piece S2 (step ST9). The moisture content measuring unit 52 acquires and stores information indicating the moisture content of the test piece S2 from the moisture sensor 32. Alternatively, the moisture content measuring unit 52 may measure the moisture content before preparing the test piece S2.

[0061] Next, if Figure 5 As shown in (b) of FIG. 1 , the second cylinder control unit 45 advances the piston rod 26 of the second cylinder 16. As a result, the scraper 17 advances, and the excess molding sand S1 remaining on the upper surface of the test tube 11 is removed.

[0062] Next, the air permeability of the test piece S2 is measured (step ST10). Figure 5 As shown in (c), in order to measure the air permeability of the test piece S2, the first cylinder control unit 44 first lowers the piston rod 22 of the first cylinder 14, and the second cylinder control unit 45 controls the second cylinder 16 to move the scraper 17 to the measuring position. Then, the air permeability measuring unit 54 controls the air source 35 to supply air 35a into the test cylinder 11 through the gap formed between the pressure plate 20 and the test piece S2, so that the air 35a passes through the test piece S2. Then, the air permeability measuring unit 54 adjusts the flow rate of the air 35a while monitoring the pressure sensor 33 so that the pressure in the test cylinder 11 becomes constant, and calculates the air permeability based on the flow rate of the air 35a when the pressure becomes constant. For example, when the pressure of the internal space 11s measured by the pressure sensor 33 is set to p and the flow rate of the air 35a is set to F, the air permeability P is calculated according to the following formula (3).

[0063] P=(F×H2) / p…(3)

[0064] Next, the compressive strength of the test piece S2 is measured (step ST11). Figure 6 As shown in (a), in order to measure the compressive strength of the test piece S2, the compression strength measuring unit 55 raises the piston rod 22 of the first cylinder 14 and makes the test piece S2 contact the measuring surface 17b. Then, the compression strength measuring unit 55 further raises the piston rod 22, applies a predetermined pressure to the test piece S2 from the pressure plate 20, and destroys the test piece S2. Then, the compression strength measuring unit 55 obtains the load when the test piece S2 is destroyed from the load sensor 15.

[0065] Next, the compression strength measuring unit 55 divides the load when the test piece S2 is broken by the cross-sectional area of ​​the test piece S2 (i.e., the cross-sectional area of ​​the internal space 11c) to obtain the compression strength. That is, when the cross-sectional area of ​​the internal space 11s of the test tube 11 perpendicular to the axis Z is set to A [cm 2 ], when the breaking load of the test piece S2 is W [N], the compressive strength σ [N / cm 2 ] is calculated according to the following formula (4).

[0066] σ=W / A…(4)

[0067] After determining the compressive strength σ, Figure 6 As shown in (b) of FIG. 1 , the second cylinder control unit 45 advances the piston rod 26 of the second cylinder 16. As a result, the test piece S2 is removed.

[0068] Next, the compressive strength σ is corrected based on the difference between the target height and the measured value of the height of the test piece S2 (step ST12). The sand filling height H1 is obtained based on the predicted value of CB, so the height H2 of the test piece S2 produced by the compressed molding sand S1 may deviate from the target height. The compressive strength σ depends on the height H2 of the test piece S2, so when the height H2 of the test piece S2 deviates from the target height, the compressive strength σ obtained by formula (4) becomes a value deviating from the true compressive strength.

[0069] For example, Figure 7 This is a graph showing the relationship between the height of the test piece and the compressive strength when the same molding sand is used to make test pieces of different heights and the compressive strength of each test piece is measured. Figure 7 As shown in FIG. 1 , a linear relationship is confirmed between the height of the test piece and the compressive strength. Specifically, the higher the height of the test piece, the smaller the measured value of the compressive strength is than the true compressive strength, and the lower the height of the test piece, the larger the measured value of the compressive strength is than the true compressive strength.

[0070] If we use this relationship, Figure 8As shown, when the height of the test piece is higher than the target height (50 mm), the measured value of the compressive strength is corrected to be larger, and when the height of the test piece is lower than the target height (50 mm), the measured value of the compressive strength is corrected to be smaller, thereby making the measured value of the compressive strength closer to the actual compressive strength.

[0071] Therefore, for the compressive strength correction unit 56, when the height H2 of the test piece S2 measured in step ST7 is greater than the target height, the measured compressive strength σ is corrected to increase, and when the height H2 of the test piece S2 is less than the target height, the measured compressive strength σ is corrected to decrease. In addition, the greater the difference between the height H2 of the test piece S2 and the target height, the greater the correction amount of the compressive strength σ. The correction values ​​of CB, temperature, moisture content, air permeability, and compressive strength measured through a series of steps are displayed on the display device 60.

[0072] As described above, in the inspection method according to one embodiment, the molding sand S1 in the test tube 11 is compressed to prepare the test piece S2 and measure the CB of the molding sand S1, so that the CB and the compressive strength of the molding sand S1 can be measured based on a sample of the molding sand S1 in a single amount put into the test tube 11. As a result, it is not necessary to put the molding sand S1 in two times, so the number of inspection steps is reduced. As a result, the inspection time of the molding sand S1 can be shortened.

[0073] In addition, in this inspection method, when the height H2 of the test piece S2 is higher than the target height, the compression strength is corrected to be larger, and when the height H2 of the test piece S2 is lower than the target height, the compression strength is corrected to be smaller, so that the measured value of the compression strength can be close to the true compression strength. In addition, as shown in formula (3), the calculation of the air permeability P includes the height H2 of the test piece S2, so even if the height H2 of the test piece S2 deviates from the target height, the influence on the measurement of the air permeability P is small.

[0074] The above descriptions are of the molding sand inspection method and the inspection device 1 according to various embodiments, but the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the main purpose of the invention. That is, it should be noted that the above embodiments are for the purpose of illustration and description, and do not limit the scope of the present invention.

[0075] For example, in the above-mentioned embodiment, the amount of molding sand to be put into the test cylinder 11 is determined using the predicted value of CB, but the amount of molding sand to be put into the test cylinder 11 may not be determined using the predicted value of CB. For example, when the predicted value of the amount of molding sand is input by the operator, the predicted value of the amount of molding sand may be determined as the amount of molding sand to be put into the test cylinder 11. In addition, when CB can be predicted with high accuracy, it is not necessary to correct the measured value of the compressive strength.

[0076] In addition, in the above-mentioned embodiment, the amount of molding sand put into the test cylinder 11 is adjusted by controlling the position of the pressure plate 20, but the pressure plate 20 can also be kept configured at the lowermost position unchanged, and the amount of molding sand put into the test cylinder 11 can be adjusted by adjusting the supply amount of molding sand from the chute 12.

[0077] In the above embodiment, CB, temperature, moisture content, air permeability and compressive strength are measured as parameters representing the characteristics of the molding sand, but it is sufficient to measure at least one parameter. For example, in one embodiment, the molding sand can be compressed in the test tube 11 to make a test piece of the target height, and the test piece can be used to measure only the compressive strength. Even in the case of measuring only the compressive strength of the test piece, there is a case where the height of the test piece deviates from the target height. In this case, the measured value of the compressive strength can be corrected to make the measured value of the compressive strength close to the true compressive strength.

[0078] The present disclosure includes the following contents.

[0079] [Item 1] A method for inspecting molding sand according to one embodiment includes: a step of injecting molding sand into a test tube; a step of compressing the molding sand in the test tube to prepare a test piece and measuring the compaction rate (CB) of the molding sand; and a step of compressing the test piece to measure the compressive strength of the test piece.

[0080] In the above inspection method, the molding sand in the test tube is compressed to prepare a test piece and measure the CB of the molding sand, so the CB and compression strength of the molding sand can be measured based on a sample of the molding sand that is put into the test tube at one time. As a result, it is not necessary to put the molding sand in two times, so the number of inspection steps is reduced. As a result, the time for inspecting the molding sand can be shortened.

[0081] [Item 2] The inspection method described in Item 1 may also include: a step of obtaining a predicted value of CB of the molding sand; and a step of determining the amount of molding sand to be fed into the test tube in order to produce a test piece of a target height based on the predicted value of CB. By determining the amount of molding sand to be fed into the test tube based on the predicted value of CB, the height of the test piece can be brought close to the target height. By bringing the height of the test piece close to the target height, the accuracy of measuring the compressive strength can be improved.

[0082] [Item 3] The inspection method described in Item 2 further includes a step of adjusting the position of a pressurizing plate that can be raised and lowered in the test tube based on the amount of molding sand to be introduced into the test tube.

[0083] [Item 4] The inspection method described in any one of Items 1 to 3 may also include: a step of measuring the height of the test piece; and a step of correcting the compressive strength based on the difference between the target height of the test piece and the measured value of the height of the test piece. The load when the test piece is compressed and destroyed depends on the height of the test piece, so when the actual height of the test piece deviates from the target height, the measurement accuracy of the compressive strength decreases. In contrast, in this method, the compressive strength is corrected based on the difference between the target height of the test piece and the measured value of the height of the test piece, so that the measured value of the compressive strength can be close to the actual compressive strength.

[0084] [Item 5] In the inspection method described in Item 4, when the measured value of the height of the test piece is greater than the target height, the measured compression strength may be corrected to be larger, and when the measured value of the height of the test piece is less than the target height, the measured compression strength may be corrected to be smaller. When the height of the test piece is higher than the target height, the measured value of the compression strength is lower than the true compression strength, and thus the measured value of the compression strength can be brought closer to the true compression strength by increasing the compression strength. On the contrary, when the height of the test piece is less than the target height, the measured value of the compression strength is higher than the true compression strength, and thus the measured value of the compression strength can be brought closer to the true compression strength by reducing the compression strength.

[0085] [Item 6] The inspection method according to any one of Items 1 to 5 may further include a step of measuring the temperature of the molding sand before preparing the test piece.

[0086] [Item 7] The inspection method described in Item 6 may further include: a step of measuring the moisture content of the molding sand after measuring the temperature of the molding sand.

[0087] [Item 8] The inspection method described in any one of Items 1 to 7 may further include a step of measuring the air permeability of the test piece before measuring the compressive strength.

[0088] [Item 9] A method involves a molding sand inspection device comprising: a test cylinder extending in an axial direction; a chute for supplying molding sand into the test cylinder; a pressing rod having a pressure plate capable of moving in the test cylinder in an axial direction; a working cylinder having a piston rod connected to the pressing rod and capable of moving forward and backward in the axial direction; a load sensor arranged between the pressing rod and the piston rod; and a control device for controlling the movement of the chute and the working cylinder, the control device comprising: an injection control unit for controlling the chute to inject molding sand into the test cylinder; a CB measuring unit for compressing the molding sand in the test cylinder by the pressure plate to prepare a test piece and measure the compaction rate (CB) of the molding sand; and a compression strength measuring unit for measuring the compression strength of the test piece based on the load measured by the load sensor when the test piece is compressed and destroyed.

[0089] In the above inspection device, the molding sand in the test cylinder is compressed to prepare a test piece and measure the CB of the molding sand, so the CB and compression strength of the molding sand can be measured based on a sample of the molding sand that is put into the test cylinder at one time. As a result, it is not necessary to put the molding sand in two times, so the number of inspection steps is reduced. As a result, the time for inspecting the molding sand can be shortened.

Claims

1. A method for inspecting molding sand, characterized in that: include: The process of feeding molding sand into the test cylinder; A process of compressing the molding sand in the test tube to prepare a test piece and measuring the compaction rate (CB) of the molding sand; and A step of compressing the test piece to measure the compressive strength of the test piece.

2. The inspection method according to claim 1, characterized in that: Also includes: A step of obtaining a predicted value of CB of the molding sand; and A step of determining the amount of molding sand to be put into the test tube in order to produce the test piece of a target height based on the predicted value of the CB.

3. The inspection method according to claim 2, characterized in that: Also includes: A step of adjusting a position of a pressurizing plate that can be raised and lowered in the test cylinder based on the amount of molding sand to be introduced into the test cylinder.

4. The inspection method according to claim 1, characterized in that: Also includes: a step of measuring the height of the test piece; and and a step of correcting the compressive strength based on a difference between a target height of the test piece and a measured value of the height of the test piece.

5. The inspection method according to claim 4, characterized in that: When the measured value of the height of the test piece is greater than the target height, correction is made so that the measured compression strength becomes larger, and when the measured value of the height of the test piece is less than the target height, correction is made so that the measured compression strength becomes smaller.

6. The inspection method according to claim 1, characterized in that: Also includes: A step of measuring the temperature of the molding sand before preparing the test piece.

7. The inspection method according to claim 6, characterized in that: Also includes: A step of measuring the water content of the molding sand after measuring the temperature of the molding sand.

8. The inspection method according to claim 1, characterized in that: Also includes: A step of measuring the air permeability of the test piece before measuring the compressive strength.

9. An inspection device, characterized in that: have: The test cylinder extends along the axial direction; a chute for supplying molding sand into the test cylinder; A pressing rod having a pressing plate capable of moving along the axial direction in the test cylinder; A working cylinder having a piston rod connected to the pressing rod and capable of moving forward and backward along the axial direction; A load sensor, disposed between the pressing rod and the piston rod; as well as A control device controls the movement of the slide and the working cylinder, The control device comprises: An injection control unit controls the chute to inject the molding sand into the test cylinder; a CB measuring unit for compressing the molding sand in the test tube by the pressure plate to prepare a test piece and measuring the compaction rate of the molding sand, namely, CB; and The compression strength measuring unit measures the compression strength of the test piece based on the load measured by the load sensor when the test piece is compressed and broken.

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