Mold strength measurement device, mold making system, and mold strength measurement method

Abstract

To acquire strength information on the inside of a mold before mold removal.SOLUTION: A mold strength measurement device according to an embodiment acquires information on the strength of a mold having a product face and a back face on the side opposite to the product face. This mold strength measurement device comprises a cutting tool and a probe. The cutting tool forms a bottomed hole extending from the back face toward the product face at the mold. The measurement probe can be inserted into the hole and measures reactive force received from the bottom part of the hole.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a mold strength measurement device, a mold making system, and a mold strength measurement method. [Background technology]

[0002] There are known devices for measuring the strength of a mold. For example, Patent Document 1 describes a method for measuring the strength of a mold by pressing a measuring needle with a ceramic piece fixed to its tip against the surface of the mold and measuring the reaction force received from the mold when the measuring needle is inserted into the surface of the mold with a load cell connected to the measuring needle.

[0003] Furthermore, Cited Document 2 describes an apparatus for measuring the strength of the cavity surface of a mold after it has been removed, which comprises a pressing member connected to a load cell and a moving means for moving the pressing member in three axial directions, i.e., forward / backward, left / right, and up / down. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 08-43286 [Patent Document 2] Japanese Patent Application Publication No. 10-296391 Summary of the Invention [Problem to be solved by the invention]

[0005] The device described in Patent Document 1 inserts a measuring needle into the surface of the mold, so although it is possible to measure the strength of the mold surface, it is difficult to measure the strength of the mold's interior. If the mold is removed before the interior has sufficiently hardened, the mold may collapse or become distorted.

[0006] Therefore, there is a need for a method to obtain information about the strength inside the mold before it is removed. [Means for solving the problem]

[0007] A mold strength measuring device according to one aspect obtains information about the strength of a mold having a product surface and a back surface opposite the product surface. The mold strength measuring device includes a cutting tool and a probe. The cutting tool forms a bottomed hole in the mold that extends from the back surface toward the product surface. The measurement probe is insertable into the hole and measures the reaction force received from the bottom of the hole.

[0008] The mold strength measurement device according to this aspect can form a hole in the mold using a cutting tool, insert a measurement probe into the hole, and measure the reaction force received from the bottom of the hole. The reaction force received from the bottom of the hole is a measurement value related to the strength of the interior of the mold. Therefore, the mold strength measurement device according to this aspect can obtain information related to the strength of the interior of the mold before demolding.

[0009] The mold strength measurement device according to one embodiment may further include an elevator that raises and lowers the cutting tool and the measurement probe in the vertical direction so as to move closer to and away from the mold. By raising and lowering the cutting tool and the measurement probe in the direction closer to and away from the mold, a hole can be formed in the mold and the measurement probe can be inserted into the formed hole.

[0010] The mold strength measurement device according to one embodiment may further include a moving unit that moves the cutting tool and the measurement probe together in a direction perpendicular to the mold transport direction and the vertical direction. By moving the cutting tool and the measurement probe together, it is possible to easily position the measurement probe.

[0011] The mold strength measurement device according to one embodiment may further include a distance sensor that measures the distance to the mold, and the lifting device may move the distance sensor together with the cutting tool and the measurement probe in a vertical direction relative to the mold. In this embodiment, the vertical distance between the distance sensor and the mold can be measured.

[0012] According to one embodiment, the mold strength measurement device further includes a horizontally extending rotation axis, and the cutting tool and the measurement probe extend perpendicular to the direction of extension of the rotation axis so as to form a predetermined angle in the circumferential direction around the rotation axis, and may be coupled to each other so as to rotate integrally around the rotation axis upon rotation of the rotation axis. With this configuration, by rotating the cutting tool and the measurement probe integrally around the rotation axis, one of the cutting tool and the measurement probe can be selectively directed toward the mold. As a result, it is possible to quickly form a hole in the mold using the cutting tool and measure the reaction force using the measurement probe.

[0013] In one embodiment, the measurement probe includes a sensor unit that measures the magnitude of the reaction force, a base unit connected to the sensor unit, and a tip unit provided on the tip side of the base, and the diameter of the tip unit may be smaller than the diameter of the base. By reducing the diameter of the tip unit, it is possible to ensure the strength of the measurement probe while suppressing damage to the mold when the measurement probe is pressed against the bottom of the hole and inserted into the bottom of the hole.

[0014] In one embodiment, the cutting tool and the measuring probe may further include a foreign matter removal device that removes foreign matter adhering to the cutting tool and the measuring probe. By removing foreign matter adhering to the measuring probe, measurement errors caused by the foreign matter can be suppressed. Note that in one embodiment, the mold may be a self-hardening mold, a thermosetting mold, or a gas-hardening mold.

[0015] A mold molding system according to one embodiment includes a transfer line for transporting a mold formed on a pattern and having a product surface in contact with the pattern and a back surface opposite the product surface, a mold strength measurement device for acquiring information about the strength of the mold, a demolding device for removing the mold from the pattern, and a line control unit for controlling the transfer line. The mold strength measurement device includes a cutting tool for forming a bottomed hole in the mold extending from the back surface toward the product surface, and a measurement probe insertable into the hole for measuring a reaction force received from the bottom of the hole. The line control unit controls the transfer line to transport the mold to the demolding device when the reaction force measured by the measurement probe or the compressive strength of the mold determined based on the reaction force is equal to or greater than a predetermined threshold, and causes the mold to wait on the transfer line when the reaction force or compressive strength is less than the predetermined threshold.

[0016] In the mold making system according to this aspect, the mold is transported to the demolding device when the reaction force or compressive strength of the mold measured before demolding is equal to or greater than a predetermined threshold, and the mold is kept waiting on the transport line when the reaction force or compressive strength of the mold is less than the predetermined threshold, thereby preventing the mold from being demolded if its strength is insufficient. As a result, collapse or distortion of the mold during demolding can be suppressed.

[0017] In one embodiment, the line control unit may control the amount of hardener added to the mold based on the reaction force or compressive strength. By controlling the amount of hardener added, the hardening speed of the mold can be adjusted so that the mold has a predetermined strength when it is demolded.

[0018] In one embodiment, the line control unit may control the amount of binder added to the mold based on the reaction force or compressive strength. By controlling the amount of binder added, the strength of the mold after hardening can be adjusted.

[0019] In one embodiment, a mold strength measurement method is provided for obtaining information about the strength of a mold having a product surface and a back surface opposite the product surface. The mold strength measurement method includes the steps of forming a bottomed hole in the mold that extends from the back surface toward the product surface, and inserting a measurement probe into the hole and measuring the reaction force that the measurement probe receives from the bottom of the hole.

[0020] As described above, according to the mold strength measurement method of this embodiment, information regarding the strength of the interior of the mold can be obtained before the mold is demolded.

[0021] The mold strength measurement method according to one embodiment may further include a step of obtaining the compressive strength of the bottom portion based on the reaction force measured by the measurement probe.

[0022] In one embodiment, the depth of the hole may be at least half the distance between the back surface and the product surface. By making the depth of the hole at least half the distance between the back surface and the product surface, it is possible to measure the strength of the portion of the mold close to the product surface, which affects the performance of the mold. Note that in one embodiment, the mold may be a self-hardening mold, a thermosetting mold, or a gas-hardening mold. [Effects of the Invention]

[0023] According to various aspects of the present disclosure, information regarding the strength of the interior of the mold can be obtained before the mold is removed. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a diagram illustrating a mold making system including a strength measurement device according to an embodiment. [Figure 2] FIG. 2 is a top view schematically showing an intensity measuring device. [Figure 3] FIG. 2 is a side view schematically showing a strength measuring device. [Figure 4] FIG. 2 is a side view schematically showing a measurement unit. [Figure 5] 1 is a flowchart illustrating a mold making method according to one embodiment. [Figure 6] 1 is a flowchart illustrating a mold strength measurement method according to an embodiment. [Figure 7] 1 is a cross-sectional view schematically illustrating a step of a mold strength measurement method according to an embodiment. [Figure 8] 1 is a cross-sectional view schematically illustrating a step of a mold strength measurement method according to an embodiment. [Figure 9] 1 is a cross-sectional view schematically illustrating a step of a mold strength measurement method according to an embodiment. [Figure 10] 1 is a cross-sectional view schematically illustrating a step of a mold strength measurement method according to an embodiment. [Figure 11] 1 is a cross-sectional view schematically illustrating a step of a mold strength measurement method according to an embodiment. [Figure 12] 1 is a cross-sectional view schematically illustrating a step of a mold strength measurement method according to an embodiment. [Figure 13] 1 is a cross-sectional view schematically illustrating a step of a mold strength measurement method according to an embodiment. [Figure 14] FIG. 10 is a top view schematically illustrating a modified example of a mold making system. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, identical or equivalent elements will be designated by the same reference numerals, and redundant description will not be repeated. The dimensional ratios of the drawings do not necessarily match those in the description. The terms "upper," "lower," "left," and "right" are based on the illustrated state and are for convenience only.

[0026] In the following description, the mold transport direction is referred to as the X direction, the horizontal direction perpendicular to the X direction is referred to as the Y direction, and the direction perpendicular to the X and Y directions is referred to as the Z direction. The X and Y directions are horizontal directions, and the Z direction is a vertical direction. The terms "upstream" and "downstream" are used with reference to the mold transport direction.

[0027] Fig. 1 is a schematic diagram of a mold making system including a strength measurement device according to one embodiment. The mold making system 1 shown in Fig. 1 makes molds 12 used in the production of castings. As shown in Fig. 1, the mold making system 1 includes a kneading device 2, a strength measurement device (mold strength measurement device) 4, a demolding device 5, a frame alignment device 6, a line control unit 8, and a conveying line 10.

[0028] The kneading device 2 produces mixed sand, which is the material for the mold 12. In one embodiment, the mixed sand contains foundry sand, a binder, and a hardener. The foundry sand, the binder, and the hardener are supplied to the kneading device 2 from a sand supplying device 2a, a binder supplying device 2b, and a hardener supplying device 2c, respectively. The binder is an inorganic or organic binder. Examples of inorganic binders include water glass and cement. Examples of organic binders include furan resin, urethane resin, and phenol resin.

[0029] The curing agent used depends on the type of binder. For example, when furan resin is used as the binder, an organic acid is used as the curing agent. When phenolic resin is used as the binder, an organic ester or polyisocyanate is used as the curing agent. In one embodiment, multiple types of curing agents with different curing rates may be added to the kneading device 2. The kneading device 2 kneads the added foundry sand, binder, and curing agent to produce mixed sand. The mixed sand containing foundry sand, binder, and curing agent becomes the material for a self-hardening mold that hardens over time.

[0030] The mixed sand produced by the kneading device 2 is transported to a molding shop, where a mold 12 is formed. The mold 12 has a molding flask 14. For example, the mixed sand produced by the kneading device 2 is discharged from the discharge port of the kneading device 2 and filled into a molding flask 14, which is placed on a model 18 placed on a surface plate 16. The mixed sand filled into the molding flask 14 is compacted by workers at the molding shop to produce the mold 12. The mold 12 produced at the molding shop is, for example, a top mold or bottom mold. If the mixed sand contains foundry sand, a binder, and a hardener, the mold 12 will be a self-hardening mold that hardens over time.

[0031] Figure 3 is a cross-sectional view showing an example of a mold 12 that has been made. As shown in Figure 3, the mold 12 is made on a pattern 18 that has a shape corresponding to the shape of the product to be cast. The mold 12 has a product surface 12a that contacts the pattern 18 and a back surface 12b that is located on the opposite side of the product surface 12a. The made mold 12 is transported by a transport line 10 toward a strength measuring device 4.

[0032] The conveying line 10 conveys the molds 12 along the conveying direction (X direction). The conveying line 10 conveys the manufactured molds 12 toward the pouring device 7 located downstream of the mold making system 1. Various conveying devices such as a belt conveyor, a chain conveyor, or a roller conveyor can be used as the conveying line 10. For example, if the conveying line 10 is a roller conveyor having drive rollers, the surface plate 16 will have a roller running surface that runs on the drive rollers.

[0033] The conveying line 10 may extend, for example, in a straight line between the molding place for the molds 12 and the pouring device 7, or may extend in a stepped manner. The conveying line 10 may also convey the molds 12 along a curved conveying path. The conveying line 10 sequentially conveys, for example, a plurality of molds 12 arranged at equal intervals in the conveying direction from the molding place to the pouring device 7. The conveying line 10 may be driven intermittently, for example, to convey a predetermined number of molds 12 at a time. The predetermined number of molds may be one frame or multiple frames.

[0034] The strength measuring device 4 is provided on the conveying line 10 and measures information relating to the strength of the mold 12 (hereinafter referred to as "strength information"). The strength information of the mold 12 refers to, for example, the reaction force measured by a measuring probe 23 described below, or the compressive strength of the mold 12. Details of the strength measuring device 4 will be described later. The mold 12 whose strength information has been measured by the strength measuring device 4 is conveyed along the conveying line 10 toward the demolding device 5.

[0035] The die-stripping device 5 is located downstream of the strength measuring device 4. The die-stripping device 5 is a device that strips the casting mold 12 (see Figure 3) from the pattern 18. "Die-stripping" refers to removing the casting mold 12 from the pattern 18. When the die-stripping device 5 removes the casting mold 12 from the pattern 18, a product surface 12a is formed on the casting mold 12, with the surface shape of the pattern 18 transferred to it. This product surface 12a defines a cavity, which is a space corresponding to the product shape. Note that the die-stripping device 5 may also remove the molding flask 14 from the pattern 18 in addition to the casting mold 12. The casting mold 12 stripped from the pattern 18 by the die-stripping device 5 is transported along the conveyor line 10 toward the frame alignment device 6.

[0036] The frame alignment device 6 is disposed downstream of the die-stripping device 5. The frame alignment device 6 is a device that frames the upper and lower molds 12 among the multiple molds 12 transported by the transport line 10. The frame alignment device 6 may set a core between the upper and lower molds. The frame alignment device 6 may automatically frame the upper and lower molds transported on the transport line 10, or the upper and lower molds may be framed by an operator operating the frame alignment device 6. The molds 12 whose upper and lower molds have been framed by the frame alignment device 6 are transported along the transport line 10 toward the pouring device 7.

[0037] The pouring device 7 is disposed downstream of the frame alignment device 6. The pouring device 7 pours molten metal into the mold 12 to produce a casting product having a shape corresponding to the shape of the cavity of the mold 12. The operation of the pouring device 7 is controlled, for example, by a line control unit 8. In one embodiment, the mold 12 pours molten metal into the mold 12 under conditions (amount of molten metal poured, pouring speed, etc.) corresponding to a control signal from the line control unit 8. The mold 12 into which the molten metal has been poured is transported by a transport line 10 to an area where subsequent processes are performed, and the casting product is removed from the mold 12.

[0038] The line control unit 8 is a computer such as a PLC (Programmable Logic Controller) equipped with a processor, a storage device, an input device, a display device, a communication device, etc., and controls the overall operation of the mold making system 1. The line control unit 8, for example, loads programs stored in the storage device and executes the loaded programs on the processor, thereby realizing various functions described below. The line control unit 8 allows an operator to use the input device to input commands and other operations to manage the mold making system 1, and the display device can visualize and display the operating status of the mold making system 1.

[0039] The line control unit 8 is connected to be able to communicate with the kneading device 2, sand supplying device 2a, binder supplying device 2b, hardener supplying device 2c, strength measuring device 4, die-cutting device 5, frame alignment device 6, and conveying line 10. The line control unit 8 sends control signals to the kneading device 2, sand supplying device 2a, binder supplying device 2b, hardener supplying device 2c, strength measuring device 4, die-cutting device 5, frame alignment device 6, and conveying line 10, and controls the operation of these devices.

[0040] For example, the line control unit 8 receives strength information of the mold 12 measured by the strength measurement device 4, and when the strength information of the mold 12 is equal to or greater than a predetermined threshold, controls the conveyance line 10 to convey the mold 12 to the demolding device 5. Then, the line control unit 8 controls the demolding device 5 to demold the mold 12 from the pattern 18. On the other hand, when the strength information of the mold 12 is less than the predetermined threshold, the line control unit 8 causes the mold 12 to wait on the conveyance line 10 for a predetermined time. Furthermore, the line control unit 8 may control the amounts of foundry sand, binder, and hardener supplied to the kneading device 2 from the sand supplying device 2a, binder supplying device 2b, and hardener supplying device 2c, depending on the strength information of the mold 12 measured by the strength measurement device 4.

[0041] In one embodiment, the mold making system 1 may further include a positioning unit 41. The positioning unit 41 positions the mold 12 on the conveyor line 10 so that the mold 12 is located at a measurement position. The measurement position is a position where strength information of the mold 12 is measured by the strength measurement device 4, and is set, for example, below the strength measurement device 4. The positioning unit 41 has a sensor that detects the approach of the mold 12. For example, as shown in FIG. 2, the positioning unit 41 may include two proximity switches. The two proximity switches are arranged along the conveyance direction (X direction) of the conveyor line 10. In the example shown in FIG. 2, the positioning unit 41 includes a proximity switch 41a arranged upstream in the conveyance direction and a proximity switch 41b arranged downstream in the conveyance direction.

[0042] When proximity switches 41a and 41b detect the approach of molds 12 being transported on transport line 10, they send a detection signal to line control unit 8, causing transport line 10 to stop. More specifically, when line control unit 8 receives a signal from proximity switch 41a detecting the approach of surface platen 16, it controls transport line 10 to slow down the transport speed of molds 12. Then, when line control unit 8 receives a signal from proximity switch 41b detecting the approach of surface platen 16, it controls transport line 10 to stop the transport of molds 12. As described above, by slowing down the transport speed of molds 12 when molds 12 approach the measurement position and then stopping the transport of molds 12 when molds 12 reach the measurement position, it is possible to accurately stop molds 12 at the measurement position.

[0043] The size of the molds 12 transported on the transport line 10 may vary depending on the size of the casting product to be manufactured. In the example of Figure 2, multiple molds 12 of different sizes are transported on the transport line 10. The surface plate 16 is large enough to accommodate the largest mold 12 designed for it. The mold 12 can be placed approximately in the center of the surface plate 16.

[0044] Next, the strength measurement device 4 will be described in detail with reference to Figures 2 and 3. Figure 2 is a top view that schematically shows a strength measurement device according to one embodiment. Figure 3 is a side view that schematically shows a strength measurement device according to one embodiment. As shown in Figure 2, the strength measurement device 4 is disposed above the conveying line 10 and measures strength information of the molds 12 conveyed by the conveying line 10. In the example shown in Figure 2, a long beam member 26 that extends in the Y direction across the conveying line 10 is provided above the conveying line 10, and the beam member 26 is supported by a frame 25 that is disposed outside the conveying line 10. The strength measurement device 4 is attached to the beam member 26 above the conveying line 10.

[0045] The strength measurement device 4 measures strength information of the mold 12 placed at the measurement position. As shown in Fig. 3, the strength measurement device 4 includes a measurement unit 20, a distance sensor 31, an elevator device 32, a slider 33, and a control device 35.

[0046] 4 is a side view of the measurement unit 20 as viewed from the X direction. As shown in FIG. 4, the measurement unit 20 includes a main body 21, a cutting tool 22, and a measurement probe 23. The main body 21 is formed in a substantially L-shape and holds the cutting tool 22 and the measurement probe 23. The main body 21 is provided with a rotation axis R that extends in the Y direction. The rotation axis R is, for example, the rotation axis of a rotary actuator 24. The driving force of the rotary actuator 24 causes the main body 21 to rotate about the rotation axis R.

[0047] The cutting tool 22 is a long tool such as a drill, end mill, or hole saw for forming a hole in the mold 12. As will be described later, the cutting tool 22 forms a bottomed hole in the mold 12 extending from the back surface 12b to the product surface 12a. As shown in FIG. 4, the cutting tool 22 extends in a radial direction (a direction perpendicular to the extension direction of the rotation axis R) with respect to the axial direction of the rotation axis R. A cutting edge for forming a hole in the mold 12 is formed at the tip of the cutting tool 22. Just before forming a hole in the mold 12, the tip of the cutting tool 22 faces downward. The base end of the cutting tool 22 is connected to a drive source 22a, such as an electric motor, disposed inside the main body 21. The cutting tool 22 rotates about its axis when driven by the drive source 22a.

[0048] The measurement probe 23 can be inserted into a hole formed by the cutting tool 22 and measures the reaction force received from the bottom of the hole. As shown in FIG. 4, the measurement probe 23 is elongated and extends radially relative to the axial direction of the rotation axis R. The measurement probe 23 includes a base 23a and a tip 23b. A sensor 23c that measures the reaction force (load) received by the measurement probe 23 is provided on the proximal end side of the base 23a. The sensor 23c includes, for example, a load cell or a pressure sensor. The tip 23b is detachably connected to the tip side of the base 23a. The diameter of the tip 23b may be smaller than the diameter of the base 23a.

[0049] As described above, the cutting tool 22 and the measurement probe 23 rotate integrally around the rotation axis R in accordance with the rotation of the rotation axis R. In one embodiment, the cutting tool 22 and the measurement probe 23 may form an angle of 90° (a predetermined angle) in the circumferential direction around the rotation axis R. In this case, when the rotation axis R is at a first rotation angle, the extension direction of the cutting tool 22 is perpendicular to the back surface 12b of the mold 12 placed at the measurement position, and the tip of the cutting tool 22 points downward. Meanwhile, the extension direction of the measurement probe 23 is horizontal to the back surface 12b of the mold 12. In contrast, when the rotation angle of the rotation axis R is at a second rotation angle that is 90° shifted from the first rotation angle, the extension direction of the measurement probe 23 is perpendicular to the back surface 12b of the mold 12 placed at the measurement position, and the tip of the measurement probe 23 points downward. Meanwhile, the extension direction of the cutting tool 22 is horizontal to the back surface 12b of the mold 12.

[0050] The measurement unit 20 is fixed to a bracket 29. As shown in FIG. 4 , positioning bolts B1 and B2 may be provided between the measurement unit 20 and the bracket 29. The bolts B1 and B2 are spaced apart in the X direction and configured so that the amount of protrusion from the surface of the bracket 29 can be individually adjusted. For example, the bolt B1 is configured so that the head of the bolt B1 abuts against the main body 21 of the measurement unit 20 when the rotation axis R is at a first rotation angle, thereby restricting further rotation of the rotation axis R. On the other hand, the bolt B2 is configured so that the head of the bolt B2 abuts against the main body 21 of the measurement unit 20 when the rotation axis R is at a second rotation angle, thereby restricting further rotation of the rotation axis R. By adjusting the amount of protrusion of the bolts B1 and B2 from the surface of the bracket 29, the tip of the cutting tool 22 when the rotation axis R is at the first rotation angle and the tip of the measurement probe 23 when the rotation axis R is at the second rotation angle are positioned at the same position. Positioning the metrology unit 20 in this manner allows the measurement probe 23 to be quickly inserted into the hole formed in the mold 12 by the cutting tool 22 .

[0051] The distance sensor 31 is fixed to the bracket 29 together with the measurement unit 20. For example, a laser sensor, an ultrasonic sensor, or a contact sensor is used as the distance sensor 31. The distance sensor 31 is placed above the transfer line 10 and measures the distance between the distance sensor 31 and the mold 12 placed on the transfer line 10. When no mold 12 is present on the transfer line 10, the distance sensor 31 outputs a signal indicating the distance from the distance sensor 31 to the top surface of the surface plate 16 or the model 18.

[0052] The lifting device 32 is provided between the bracket 28 and the bracket 29. The lifting device 32 is, for example, an actuator that moves the bracket 29 up and down (Z direction). As the lifting device 32, for example, a hydraulic cylinder, an air cylinder, or an electric cylinder is used. When the bracket 29 is moved up and down by driving the lifting device 32, the measurement unit 20 and the distance sensor 31 fixed to the bracket 29 move integrally in the direction approaching and moving away from the mold 12 (Z direction).

[0053] Bracket 28 is fixed to slider 33. Slider 33 is provided on beam member 26 and connected to a drive mechanism including, for example, a ball screw, a linear guide, a servo motor, etc. Slider 33 drives the drive mechanism to move bracket 28, lifting device 32, and bracket 29 along the extension direction (Y direction) of beam member 26. As slider 33 moves, measurement unit 20 fixed to bracket 29 moves in the Y direction. In other words, slider 33 functions as a moving part that moves cutting tool 22 and measurement probe 23 together in a horizontal direction perpendicular to the transport direction of mold 12.

[0054] The control device 35 is a computer such as a PLC (Programmable Logic Controller) equipped with a processor, a storage device, an input device, a display device, a communication device, etc., and controls the overall operation of the strength measurement device 4. The control device 35 performs various functions, which will be described later, by, for example, loading a program stored in the storage device and executing the loaded program on the processor. The control device 35 allows an operator to use the input device to input commands and other operations to manage the mold making system 1, and the display device can visualize and display the operating status of the mold making system 1.

[0055] The control device 35 is communicatively connected to the measurement unit 20, the lifting device 32, the slider 33, and the line control unit 8. For example, the control device 35 sends control signals to the measurement unit 20, the lifting device 32, and the slider 33 to control the rotation angle of the rotation axis R, the operation of the drive source 22a, the position of the measurement unit 20 in the Z direction, and the position of the slider 33 in the Y direction. More specifically, the control device 35 controls the rotation angle of the rotation axis R and the position of the measurement unit 20 to form a hole in the mold 12 using the cutting tool 22 and to measure strength information about the interior of the mold 12 using the measurement probe 23.

[0056] The control device 35 may also store strength information of the mold 12 in association with mold information related to the mold 12. Examples of mold information include the serial number of the mold 12, dimensional information of the mold 12, molding time, and molding conditions. Examples of molding conditions include the amounts of binder and hardener added to the mixed sand, the types of molding sand, binder, and hardener, the sand-to-metal ratio, air temperature, humidity, sand temperature before mixing, and molding time.

[0057] The control device 35 may store the strength information and mold information in an RFID (Radio Frequency Identifier) ​​tag affixed to the flask 14, the platen 16, or the pattern 18. A barcode, number, or character string from which the mold information can be read may be affixed to or engraved on the mold 12. A barcode or the like from which the mold information can be read may be affixed to or engraved on the flask 14, the platen 16, or the pattern 18.

[0058] In one embodiment, the strength measurement device 4 may further include a foreign matter removal device 38 that removes foreign matter adhering to the cutting tool 22 and the measurement probe 23. The foreign matter removal device 38 is, for example, a blower that sprays air toward the measurement probe 23 to remove molding sand or the like adhering to the measurement probe 23. The foreign matter removal device 38 may also be a brush that cleans the measurement probe 23, a suction device that sucks foreign matter from the measurement probe 23, or a vibration device that applies vibrations to the measurement probe 23.

[0059] Next, a mold making method using mold making system 1 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing a mold making method according to one embodiment. Each step in the flowchart shown in Fig. 5 is executed by, for example, line control unit 8 controlling each functional element of mold making system 1.

[0060] In one embodiment of the mold-making method, first, foundry sand, binder, and hardener are supplied from sand supplying device 2a, binder supplying device 2b, and hardener supplying device 2c to kneading device 2, respectively. Kneading device 2 kneads the supplied foundry sand, binder, and hardener to produce mixed sand (step ST11). Next, an operator compacts the mixed sand to form mold 12 (step ST12).

[0061] Next, the strength measurement device 4 measures strength information of the mold 12 that has been produced (step ST13). The strength measurement device 4 measures, for example, the reaction force of the mold 12 measured by the strength measurement device 4, or the compressive strength of the mold 12 determined based on the reaction force. Next, the line control unit 8 determines whether the strength information of the mold 12 measured by the strength measurement device 4 is equal to or greater than a predetermined threshold (step ST14). If the strength information of the mold 12 is equal to or greater than the predetermined threshold, for example, if the reaction force of the mold 12 measured by the strength measurement device 4, or the compressive strength of the mold 12 determined based on the reaction force, is equal to or greater than the predetermined threshold, the line control unit 8 controls the conveyance line 10 to transport the mold 12 toward the demolding device 5, which then demolds the mold 12 from the model 18 (step ST15). On the other hand, if the strength information of the mold 12 is below a predetermined threshold, for example, if the reaction force of the mold 12 measured by the strength measuring device 4 or the compressive strength of the mold 12 determined based on the reaction force is below a predetermined threshold, the line control unit 8 causes the mold 12 to wait on the conveying line 10 for a predetermined time to allow the mold 12 to harden (step ST16). After the predetermined time has elapsed, the strength measuring device 4 measures the strength of the mold 12 again.

[0062] As described above, in the mold making method according to one embodiment, mold 12 is stripped from pattern 18 when the strength of the interior of mold 12 is equal to or greater than a predetermined threshold, and mold 12 is kept waiting on the conveyor line when the strength of the mold is less than the predetermined threshold, thereby preventing pattern 18 from being stripped from mold 12 when its strength is insufficient. As a result, collapse or distortion of mold 12 during stripping is suppressed.

[0063] In one embodiment, the line control unit 8 may control the amount of hardener added to the mold 12 based on strength information about the mold 12. For example, if the reaction force or compressive strength of the mold 12 initially measured by the strength measurement device 4 is less than a predetermined threshold, the line control unit 8 may increase the amount of hardener supplied from the hardener supply device 2c to the kneading device 2. The line control unit 8 may also adjust the blending ratio of multiple hardeners with different hardening rates, depending on the strength information about the mold 12 initially measured by the strength measurement device 4. As described above, the hardening rate of the mold 12 can be controlled by adjusting the blending ratio or the amount of hardener added.

[0064] The line control unit 8 may control the amount of binder added to the mold 12 based on the strength information of the mold 12. For example, the line control unit 8 may increase the amount of binder added supplied from the binder supply device 2b to the kneading device 2 when the reaction force or compressive strength of the mold 12 after a predetermined time has elapsed is less than a predetermined threshold. By increasing the amount of binder added, the strength of the mold 12 after the predetermined time has elapsed can be improved.

[0065] Next, a mold strength measurement method using the strength measurement device 4 will be described in detail with reference to Fig. 6. Fig. 6 is a flowchart showing a mold strength measurement method according to one embodiment. In the mold strength measurement method shown in Fig. 6, the compressive strength of the mold 12 is obtained as strength information. Each step of the flowchart shown in Fig. 6 is executed by, for example, the control device 35 controlling each functional element of the strength measurement device 4.

[0066] In one embodiment of the mold strength measurement method, the control device 35 first moves the measurement unit 20 above the mold 12 (step ST21). For example, the control device 35 controls the slider 33 to move the measurement unit 20 and the distance sensor 31 in the Y direction while continuously or intermittently receiving measurement data from the distance sensor 31. The control device 35 then recognizes the position where the height distance measured by the distance sensor 31 changes suddenly as the position of the molding flask 14. The control device 35 positions the measurement unit 20 above the mold 12 by moving the measurement unit 20 in the Y direction a predetermined distance from the position of the molding flask 14.

[0067] Next, the control device 35 lowers the measurement unit 20 to form a hole 30 in the mold 12 (step ST22). For example, the control device 35 controls the rotary actuator 24 of the measurement unit 20 to point the tip of the cutting tool 22 toward the back surface 12b of the mold 12, and controls the drive source 22a to rotate the cutting tool 22 about its axis. Next, the control device 35 controls the lifting device 32 to move the measurement unit 20 downward. As a result, as shown in FIG. 7 , the cutting tool 22 perforates the mold 12 placed on the conveyor line 10, forming a bottomed hole 30 in the mold 12 that extends from the back surface 12b toward the product surface 12a.

[0068] In this case, the hole 30 formed in the mold 12 may have a depth equal to or greater than half the distance between the back surface 12b and the product surface 12a in the Z direction. That is, the hole 30 is formed in the Z direction from the midpoint 12m between the back surface 12b and the product surface 12a toward the product surface 12a. The depth of the hole 30 formed in the mold 12 is adjusted by the amount of lowering of the cutting tool 22. In one embodiment, the control device 35 may measure the distance to the pattern 18 using a sensor during the molding of the mold 12 and determine the lowest position of the cutting tool 22 so that the mold 12 is cut just before the pattern 18. The control device 35 may also obtain the height of the mold 12 from an RFID tag affixed to the mold 12 and determine the lowest position of the cutting tool 22 based on the height of the mold 12. The control device 35 may form the hole 30 in a position that does not interfere with the pattern 18 so as to prevent the pattern 18 from being damaged when the hole 30 is formed in the mold 12.

[0069] Next, as shown in FIG. 8, the control device 35 controls the lifting device 32 to move the measurement unit 20 upward. Next, as shown in FIG. 9, the control device 35 rotates the measurement unit 20 around the rotation axis R so that the tip of the measurement probe 23 faces the mold 12 (step ST23). Next, the control device 35 controls the lifting device 32 to move the measurement unit 20 downward. As a result, the measurement probe 23 is inserted into the hole 30 formed in the mold 12 as shown in FIG. 10, and the tip of the measurement probe 23 is pressed against the bottom 30b of the hole 30. Then, as shown in FIG. 11, the control device 35 controls the lifting device 32 to move the measurement unit 20 further downward, and the measurement probe 23 penetrates the bottom 30b by a predetermined depth (e.g., 50 mm). At this time, the measurement probe 23 measures the reaction force it receives from the bottom 30b (step ST24). The reaction force from the bottom 30b is a measurement of the strength of the interior of the mold 12 and indicates the hardened state of the mold 12.

[0070] After measuring the reaction force from the bottom 30b, the control device 35 raises the measurement probe 23 and pulls it out of the hole 30, as shown in Fig. 12. At this time, the foreign matter removal device 38 sprays air toward the tip of the measurement probe 23, for example, to remove foreign matter such as molding sand adhering to the measurement probe 23 (step ST25).

[0071] Next, the control device 35 calculates the compressive strength from the reaction force of the mold 12 measured by the measurement probe 23 (step ST26). For example, the control device 35 stores correlation data showing the relationship between the reaction force measured by the measurement probe 23 and the compressive strength, and uses the correlation data to convert the measured reaction force of the mold 12 into compressive strength. At this time, the control device 35 may store the calculated compressive strength inside the mold 12 in association with mold information about the mold 12. Note that the measured reaction force is a measurement value related to the strength inside the mold 12 and represents the hardened state inside the mold 12. Therefore, the control device 35 may store the measured reaction force as strength information inside the mold 12 without converting it into compressive strength.

[0072] As described above, the strength measuring device 4 according to the embodiment forms a hole 30 in the mold 12 using the cutting tool 22, and then inserts the measurement probe 23 into the hole 30 to measure the reaction force received from the bottom 30b of the hole 30. The reaction force received from the bottom 30b of the hole 30 is a measurement value related to the strength inside the mold 12 and indicates the hardened state of the mold 12. Therefore, the strength measuring device 4 can measure strength information inside the mold 12 before demolding. In particular, self-hardening molds are typically formed by compacting mixed sand. When compacting mixed sand during molding, differences in the packing density of the sand typically occur between the product surface 12a and the back surface 12b. This can result in variations in the strength of the mold between the product surface 12a and the back surface 12b. This can make it difficult to estimate the strength information of the product surface 12a from the strength information of the back surface 12b of the mold 12. In contrast, the strength measuring device 4 has a hole 30 formed that extends from the back surface 12b of the mold 12 to just before the product surface 12a, so that strength information of the mold 12 on the product surface 12a side, which greatly affects the performance of the mold 12, can be obtained.

[0073] The mold making system, strength measurement device, and strength measurement method according to various embodiments have been described above, but the invention is not limited to the above-described embodiments and various modifications can be made without departing from the spirit of the invention.

[0074] For example, the mold 12 is not limited to a self-hardening mold as long as it is a special mold. Special molds include, for example, self-hardening molds, thermosetting molds, and gas-hardening molds. Thermosetting molds are manufactured by a thermosetting process such as the shell molding method or hot box method. Gas-hardening molds are manufactured by a gas-hardening process in which, for example, water glass is mixed with foundry sand to form a mold, and then carbon dioxide gas is injected into the mold.

[0075] The intensity measurement device 4 may not include the control device 35. In one embodiment, the function of the control device 35 may be integrated into the line control unit 8, and the line control unit 8 may control the operations of the measurement unit 20, the distance sensor 31, the lifting device 32, and the slider 33.

[0076] In the mold making method shown in Figure 5, if the strength information of the mold 12 measured by the strength measuring device 4 is below a predetermined threshold, the mold 12 is made to wait on the conveying line 10. However, if the strength information of the mold 12 is below a predetermined threshold, the line control unit 8 may convey the mold 12 to a waiting station off the conveying path on the conveying line 10, and make the mold 12 wait at the waiting station for a predetermined time.

[0077] In the embodiment shown in FIG. 4, the cutting tool 22 and the measurement probe 23 are connected to each other so that they can rotate together around the rotation axis R, but the cutting tool 22 and the measurement probe 23 do not have to be connected to each other. For example, as shown in FIG. 13, the strength measurement device 4 may include a slider 33A that moves the cutting tool 22 in the Y direction and a slider 33B that moves the measurement probe 23 in the Y direction. The slider 33A moves the cutting tool 22 above the mold 12, and the elevator device 32A lowers the cutting tool 22 to form a hole in the mold 12. The slider 33B moves the measurement probe 23 above the hole formed in the mold 12, and the elevator device 32B lowers the measurement probe 23 to press the tip of the measurement probe 23 against the bottom of the hole. The measurement probe 23 is then inserted into the bottom of the hole so that the tip of the measurement probe 23 enters the mold 12, and the reaction force received from the mold 12 is measured. In this way, even with a configuration in which the cutting tool 22 and the measurement probe 23 are moved individually in the Y direction, it is possible to measure strength information inside the mold 12 before demolding.

[0078] In the strength measurement device 4 shown in FIG. 3 , the distance sensor 31 is configured to move integrally with the measurement unit 20, but the distance sensor 31 may also be moved separately from the measurement unit 20. For example, the distance sensor 31 may be attached to the frame 25 so as to be movable in the Z direction. In such a configuration, by measuring the distance in the Y direction between the distance sensor 31 and the mold 12 while moving the distance sensor 31 in the Z direction, it is possible to identify the position of the mold 12 in the Y direction and the position of the back surface 12b of the mold 12 in the Z direction. Therefore, it is possible to identify the position where a hole is to be formed in the mold 12 based on the position of the mold 12 and the position of the back surface 12b identified by the distance sensor 31.

[0079] In the embodiment shown in FIG. 2, the mold 12 is positioned at the measurement position by a positioning unit 41 having two proximity switches. However, the positioning unit 41 may also position the mold 12 without using proximity switches. For example, as shown in FIG. 14, the mold making system may include a pair of stoppers 41C that rotate about an axis extending in the Z direction to open and close. When closed, these pair of stoppers 41C contact the surface plate 16 to restrict movement in the X direction. When measurement unit 20 completes measurement of the strength information of the mold 12, the pair of stoppers 41C rotate about the axis to open, allowing the mold 12 to pass downstream. Note that the pair of stoppers 41C may be pins that engage with bushings provided on the surface plate 16.

[0080] In the above-described embodiment, the measuring unit 20 is moved in the Y direction and the Z direction by the slider 33 and the elevator 32, respectively. However, the measuring unit 20 may be moved using a robot. For example, the robot may be a three-axis Cartesian robot, which moves the measuring unit 20 and the distance sensor 31 integrally in the X direction, the Y direction, and the Z direction. Examples of the robot include an articulated robot, a parallel link robot, and a scalar robot. The robot is fixed to a beam member 26 above the conveyor line 10, for example. The robot may be a single-axis or two-axis robot.

[0081] 1, the transfer line 10 is provided to transfer the molds 12 along a linear transfer path, but the transfer line 10 may transfer the molds 12 along a circular transfer path. The various embodiments described above can be combined to the extent that no contradictions occur. [Explanation of symbols]

[0082] 1...Mold forming system, 4...Strength measurement device (mold strength measurement device), 5...Die removal device, 8...Line control unit, 10...Conveyor line, 12...Mold, 12a...Product surface, 12b...Back surface, 18...Model, 22...Cutting tool, 23...Measuring probe, 23a...Base, 23b...Tip, 30...Hole, 30b...Bottom, 31...Distance sensor, 32...Lifting device, 38...Foreign matter removal device

Claims

1. A mold strength measurement device for acquiring information about the strength of a mold having a product surface and a back surface opposite to the product surface, a cutting tool that forms a bottomed hole in the mold, the hole extending from the back surface toward the product surface; a measurement probe that can be inserted into the hole and measures a reaction force received from the bottom of the hole; A mold strength measuring device comprising:

2. The mold strength measuring device according to claim 1 , further comprising an elevator device that raises and lowers the cutting tool and the measurement probe in the vertical direction so as to approach and move away from the mold.

3. The mold is transported in a transport direction along a horizontal direction, The mold strength measuring device according to claim 2 , further comprising a moving unit that moves the cutting tool and the measurement probe together in a direction perpendicular to the mold transfer direction and the vertical direction.

4. Further provided is a distance sensor for measuring a distance to the mold; The mold strength measuring device according to claim 2 , wherein the lifting device moves the distance sensor together with the cutting tool and the measurement probe in the vertical direction relative to the mold.

5. Further comprising a rotation axis extending in a horizontal direction, 5. The mold strength measurement device according to claim 1, wherein the cutting tool and the measurement probe extend in a direction perpendicular to the extension direction of the rotation axis so as to form a predetermined angle in the circumferential direction around the rotation axis, and are connected to each other so as to rotate integrally around the rotation axis by rotation of the rotation axis.

6. the measurement probe includes a sensor unit that measures the magnitude of the reaction force, a base unit connected to the sensor unit, and a tip unit provided on a tip side of the base unit, 6. The mold strength measurement device according to claim 1, wherein the diameter of the tip portion is smaller than the diameter of the base portion.

7. a foreign matter removal device for removing molding sand adhering to the measurement probe; 7. The mold strength measurement device according to claim 1, wherein the foreign matter removal device is a blower that injects air onto the measurement probe, a brush that cleans the measurement probe, a suction device that sucks up molding sand adhering to the measurement probe, or a vibration device that applies vibration to the measurement probe.

8. 8. The mold strength measuring device according to claim 1, wherein the mold is a self-hardening mold, a thermosetting mold, or a gas-hardening mold.

9. a conveying line for conveying a mold formed on a pattern and having a product surface in contact with the pattern and a back surface opposite to the product surface; a mold strength measurement device that acquires information about the strength of the mold; a demolding device for removing the mold from the model; a line control unit that controls the conveying line; Equipped with Mold strength measurement device: a cutting tool that forms a bottomed hole in the mold, the hole extending from the back surface toward the product surface; a measurement probe that can be inserted into the hole and measures a reaction force received from the bottom of the hole; Including, The line control unit When the reaction force measured by the measurement probe or the compressive strength of the mold determined based on the reaction force is equal to or greater than a predetermined threshold, the conveying line is controlled to convey the mold to the demolding device; A mold making system that causes the mold to wait on the conveying line when the reaction force or the compressive strength is less than the predetermined threshold.

10. A sand supplying device for supplying foundry sand; a curing agent supplying device for supplying a curing agent; a binder supplying device that supplies a binder; a kneading device for kneading the foundry sand, the hardener, and the binder to produce the mixed sand for the mold; Further provided with 10. The mold making system according to claim 9, wherein the line control unit controls the hardener supply device based on the reaction force or the compressive strength to control the amount of hardener added to the mold.

11. A mold making system as described in Claim 10, wherein the line control unit controls the binder supply device based on the reaction force or the compressive strength to control the amount of binder added to the mold.

12. A mold strength measurement method for acquiring information about the strength of a mold having a product surface and a back surface opposite to the product surface, forming a bottomed hole in the mold extending from the back surface toward the product surface; a step of inserting a measurement probe into the hole and measuring a reaction force that the measurement probe receives from the bottom of the hole; A mold strength measurement method, comprising:

13. The mold strength measuring method according to claim 12, further comprising the step of acquiring the compressive strength of the bottom portion based on the reaction force measured by the measurement probe.

14. The mold strength measurement method according to claim 12 or 13, wherein the depth of the hole is equal to or greater than half of the distance between the back surface and the product surface.

15. The mold strength measurement method according to any one of claims 12 to 14, wherein the mold is a self-hardening mold, a thermosetting mold, or a gas-hardening mold.

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