Casting device and emergency stop method

A casting apparatus includes a first drive unit closing or opening an upper mold and a lower mold, a second drive unit tilting the closed upper mold and lower mold, an optical sensor and a control unit. When the optical sensor detects an object during a casting period after molten metal is supplied to the upper mold and the lower mold tilted by the second drive unit until the molten metal is cooled, the control unit does not shut off power supplies to the first drive unit and the second drive unit, causes the first drive unit to continue mold closing and causes the second drive unit to hold the tilting position.

TECHNICAL FIELD

The present disclosure relates to a casting apparatus and an emergency stop method.

BACKGROUND ART

Patent Document 1 discloses a gravity type tilting die casting apparatus. This apparatus is provided with an upper frame, a lower frame, an opening/closing mechanism, a first main link member, a first sub-link member and a drive unit. An upper mold is attached to the upper frame. A lower mold is attached to the lower frame. The opening/closing mechanism opens or closes the upper mold and the lower mold by moving either the upper mold or the lower mold up and down. A top end part of the first main link member is rotatably connected to the upper frame, a bottom end part of the first main link member is rotatably connected to the lower frame, and the first main link member is provided with a rotating shaft at a central part thereof. The first sub-link member is disposed parallel to the first main link member, a top end part of the first sub-link member is rotatably connected to the upper frame, and a bottom end part of the first sub-link member is rotatably connected to the lower frame and is provided with a rotating shaft at a central part thereof. The drive unit is connected to the rotating shaft of the first main link member and rotates the first main link member around the rotating shaft. The upper frame, the lower frame, the first main link member and the first sub-link member constitute a first parallel link mechanism.

CITATION LIST

Patent Document

Patent Document 1: Japanese Patent Publication No. 5880792

SUMMARY OF INVENTION

Technical Problem

With regard to securing safety of workers, there is a conceivable measure in which a presence detector such as a light curtain is provided, and when the detector detects entry of a worker, the casting apparatus in operation may be stopped in emergency. Generally, emergency stop is realized by immediately shutting off power (power supply) to an actuator. However, when the power (power supply) to the actuator is shut off, restoration may take time depending on a casting step. In the present technical field, even in the case of emergency stop, the casting apparatus is expected to achieve immediate restoration.

Solution to Problem

An aspect of the present disclosure is a casting apparatus that forms a casting by using an upper mold and a lower mold, which can be opened, closed, and tilted, into which molten metal is poured by using gravity. The casting apparatus includes a first drive unit, a second drive unit, an optical sensor and a control unit. The first drive unit moves either the upper mold or the lower mold up and down to open or close the upper mold and the lower mold. The second drive unit tilts the upper mold and the lower mold which are closed by the first drive unit. The optical sensor is disposed in the periphery of the casting apparatus and detects an object. When an object is detected by the optical sensor, the control unit shuts off the power supply to the first drive unit and the second drive unit. When the optical sensor detects an object for a casting period after molten metal is supplied into the upper mold and the lower mold tilted by the second drive unit until the molten metal is cooled, the control unit does not shut off the power supply to the first drive unit and the second drive unit, causes the first drive unit to continue mold closing and causes the second drive unit to keep tilting position.

When the optical sensor detects an object, this casting apparatus shuts off power supply to the first drive unit and the second drive unit. Operations of the first drive unit and the second drive unit are thereby completely stopped. On the other hand, when the operations of the first drive unit and the second drive unit are completely stopped during the casting period after the molten metal is supplied into the upper mold and the lower mold tilted by the second drive unit until the molten metal is cooled, it is no longer possible to keep the tilting position, the molten metal is not fully supplied into the molds, but coagulates in such a condition, making it hard to remove the molten metal from the mold, increasing the possibility that the molds will be opened without the molten metal coagulating sufficiently. When the apparatus falls into such a situation, it takes time to recover. For this reason, when the optical sensor detects an object during the above casting period, the casting apparatus does not shut off power supply to the first drive unit and the second drive unit, the first drive unit continues mold closing and the second drive unit keeps the tilting position. This makes it possible to prevent an insufficient amount of the molten metal from coagulating or the molds from opening, and the operation can therefore be restored speedily even when the apparatus stops in emergency.

In an embodiment, the first drive unit may include a hydraulic cylinder, a first hydraulic pump supplying hydraulic oil to the hydraulic cylinder, a first pump electric motor driving the first hydraulic pump and a first drive control unit controlling the first pump electric motor. When the optical sensor detects an object during the above casting period, the power supply to the first drive control unit is not shut off, but the first hydraulic pump continues driving, torque by the hydraulic cylinder is kept, thus making it possible to continue mold closing.

In an embodiment, the first drive unit may include an electric cylinder and a first electric control unit driving the electric cylinder. When the optical sensor detects an object during the above casting period, the power supply to the first electric control unit is not shut off, and torque by the electric cylinder is kept, and so mold closing can be continued. Furthermore, since the power supply to the first electric control unit is not shut off, no origin returning processing for the electric cylinder is necessary, which eliminates the necessity for time for returning.

In an embodiment, the second drive unit may include a hydraulic motor, a second hydraulic pump supplying hydraulic oil to the hydraulic motor, a second pump electric motor driving the second hydraulic pump and a second drive control unit controlling the second pump electric motor. When the optical sensor detects an object during the above casting period, the power supply to the second drive control unit is not shut off, the second hydraulic pump continues driving, torque by the hydraulic motor is kept, and so it is possible to keep the tilting position.

In an embodiment, the second drive unit may include an electric motor and a second electric control unit driving the electric motor. When the optical sensor detects an object during the above casting period, the power supply to the second drive unit is not shut off, and torque by the electric motor is kept, and so the tilting position can be kept. Since the power supply to the second drive unit is not shut off, no origin returning processing for the electric cylinder is necessary, which eliminates the necessity for time for returning.

In an embodiment, the casting apparatus may also include an upper frame to which an upper mold is attached, a lower frame to which a lower mold is attached, a first main link member, a top end part of which is rotatably connected to the upper frame, a bottom end part of which is rotatably connected to the lower frame and a central part of which is provided with a rotating shaft, and a first sub-link member disposed parallel to the first main link member, a top end part of which is rotatably connected to the upper frame, a bottom end part of which is rotatably connected to the lower frame and a central part of which is provided with a rotating shaft. The upper frame, the lower frame, the first main link member and the first sub-link member may constitute a first parallel link mechanism. The casting apparatus operating through such a link mechanism can eliminate the necessity for time for returning.

Another aspect of the present disclosure is an emergency stop method for a casting apparatus that forms a casting by using an upper mold and a lower mold, which can be opened, closed, and tilted, into which molten metal is poured by using gravity. The casting apparatus includes a first drive unit moving either the upper mold or the lower mold up and down to open or close the upper mold and the lower mold and a second drive unit tilting the upper mold and the lower mold closed by the first drive unit. The emergency stop method includes steps of, deter mining, when an object is detected by the optical sensor disposed in the periphery of the casting apparatus, whether or not detection timing is included in a casting period after the molten metal is supplied into the tilted upper mold and lower mold until the molten metal is cooled, and performing first stop processing, when it is determined that the detection timing is not included in the casting period, in which power supplies to the first drive unit and the second drive unit are shut off or performing second stop processing, when it is determined that the detection timing is included in the casting period, in which the power supplies to the first drive unit and the second drive unit are not shut off, the first drive unit is caused to continue mold closing and the second drive unit is caused to keep tilting position.

According to this emergency stop method, it is possible to exert the same effects as those of the aforementioned casting apparatus.

Advantageous Effects of Invention

According to the present disclosure, even when the casting apparatus is stopped in emergency, normal operation can be restored speedily.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the same elements in description of the drawings are assigned the same reference numerals and duplicate description thereof will be omitted. Moreover, dimensional ratios among the drawings do not always correspond to those in the description. Terms like “up,” “down,” “left” and “right” are based on the illustrated states and used for convenience' sake.

First Embodiment

A configuration of a casting apparatus50will be described with reference toFIG. 1andFIG. 2.FIG. 1is a front view of a casting apparatus according to a first embodiment.FIG. 2is a side view of the casting apparatus inFIG. 1. An X direction and a Y direction in the drawings are horizontal directions and a Z direction is a vertical direction. Hereinafter, the X direction will also be referred to as a left-right direction and the Z direction will also be referred to as an up-down direction.

The casting apparatus50is a so-called gravity type tilting die casting apparatus into which molten metal is poured using gravity and which forms a casting using an upper mold1and a lower mold2which can be opened, closed and tilted. The molten metal to be poured can be any material. Examples of the molten metal to be used include aluminum alloy and magnesium alloy. The casting apparatus50includes a controller and is configured to be able to control operations of respective components.

As shown inFIG. 1andFIG. 2, the casting apparatus50is provided with, for example, a base frame17, an upper frame5, a lower frame6, an opening/closing mechanism21, a pair of left and right main link members7(first main link member7a, second main link member7b), a pair of left and right sub-link members8(first sub-link member8a, second sub-link member8b), a rotation actuator16and a ladle25.

The base frame17includes a base18, a drive side support frame19and a driven side support frame20. The base18is a substantially flat plate member composed by combining a plurality of members and is provided horizontally on an installation surface of the casting apparatus50. The drive side support frame19and the driven side support frame20are erected on the base18in such a way as to face each other in the left-right direction (horizontal direction) and are fixed to the base18. A pair of tilting rotation bearings9is provided at a top end part of the drive side support frame19and a top end part of the driven side support frame20.

The upper frame5is disposed above the base frame17. The upper mold1is attached to the upper frame5. More specifically, the upper mold1is mounted on an undersurface of the upper frame5via an upper mold die base3. The upper frame5is provided with the opening/closing mechanism21moving the upper mold1up and down. More specifically, the upper frame5incorporates the opening/closing mechanism21and holds the upper mold1in such a way as to be movable up and down through the opening/closing mechanism21.

The opening/closing mechanism21includes a first actuator22, a pair of left and right guide rods23and a pair of left and right guide cylinders24. The first actuator22moves either the upper mold1or the lower mold2up and down to thereby open or close the upper mold1and the lower mold2. In the present embodiment, the first actuator22moves the upper mold1up. A bottom end part of the first actuator22is mounted on a top surface of the upper mold die base3. The first actuator22extends in an up-down direction (vertical direction; Z direction here) to thereby move the upper mold1down via the upper mold die base3, and is contracted in the up-down direction to thereby move the upper mold1up via the upper mold die base3. The first actuator22may be operated by any one of electric power, hydraulic pressure and pneumatic pressure. An example of the first actuator22is a hydraulic cylinder. The guide rods23are mounted on the top surface of the upper mold die base3through the guide cylinder24mounted on the upper frame5.

The lower frame6is disposed above the base frame17and below the upper frame5. The lower mold2is attached to the lower frame6. More specifically, the lower mold2is mounted on a top surface of the lower frame6via a lower mold die base4. In the state shown inFIG. 1andFIG. 2, the upper frame5and the lower frame6face each other in the up-down direction. Similarly, the upper mold1and the lower mold2face each other in the up-down direction. The opening/closing mechanism21moves the upper mold1up and down to thereby close or open the upper mold1and the lower mold2.

The first main link member7ais a long member. The first main link member7ais, for example, a bar-like member having a rectangular cross section. A top end part of the first main link member7ais rotatably connected to the upper frame5, a bottom end part thereof is rotatably connected to the lower frame6and the first main link member7ais provided with a tilt rotating shaft10at a central part thereof. The first main link member7aincludes a main link upper rotating shaft11at the top end part thereof and a main link lower rotating shaft12at a bottom end part thereof. In the present embodiment, the first main link member7ais provided with two main link members. The second main link member7bhas the same configuration as that of the first main link member7a. The pair of main link members7is arranged in such a way as to face each other in the left-right direction (horizontal direction; X direction here) and connect the upper frame5and the lower frame6respectively. Here, the pair of main link members7is arranged in parallel in such a way as to face each other across the upper mold1and the lower mold2.

The central parts of the pair of main link members7are rotatably connected to the pair of tilting rotation bearings9via the pair of tilt rotating shafts10. The top end parts of the pair of main link members7are rotatably connected to a pair of side faces5aof the upper frame5via the pair of main link upper rotating shafts11. The bottom end parts of the pair of main link members7are rotatably connected to a pair of side faces6aof the lower frame6via the pair of main link lower rotating shafts12. When the upper mold1and the lower mold2are closed, the mounting positions of the pair of main link members7with respect to the upper frame5and the lower frame6are set so that the pair of main link members7is located at the respective centers of the upper mold1and the lower mold2in a depth direction (Y direction) orthogonal to the left-right direction and the up-down direction.

The first sub-link member8ais a long member. The first sub-link member8ais, for example, a bar-like member having a rectangular cross section. The first sub-link member8ais arranged parallel to the first main link member7a, top end parts of which are rotatably connected to the upper frame5, bottom end parts of which are rotatably connected to the lower frame6, and is provided with a sub-link central part rotating shaft15at a central part thereof. The first sub-link member8aincludes a sub-link upper rotating shaft13at a top end part thereof and a sub-link lower rotating shaft14at a bottom end part thereof. Two sub-link members are provided in the present embodiment. The second sub-link member8b(not shown) has the same configuration as that of the first sub-link member8a. The pair of sub-link members8is arranged in such a way as to face each other in the left-right direction, and connect the upper frame5and the lower frame6. The pair of sub-link members8is disposed on the pair of side faces5aand the pair of side faces6ain such a way as to be parallel to the pair of main link members7. The sub-link member8has the same length as that of the main link member7.

The top end parts of the pair of sub-link members8are rotatably connected to the pair of side faces5aof the upper frame5via the pair of sub-link upper rotating shafts13. The bottom end parts of the sub-link members8are rotatably connected to the pair of side faces6aof the lower frame6via a pair of sub-link lower rotating shafts14. The mounting position of the sub-link member8is on a side where the ladle25is disposed with respect to the main link member7. The sub-link central part rotating shaft15is placed above the base frame17. In the state inFIG. 1andFIG. 2, the sub-link central part rotating shaft15is placed on a top surface of the drive side support frame19.

In this way, the upper frame5, the lower frame6, the first main link member7aand the first sub-link member8aconstitute a parallel link mechanism (first parallel link mechanism). Similarly, the upper frame5, the lower frame6, the second main link member7band the second sub-link member8bconstitute a parallel link mechanism (second parallel link mechanism). The two parallel link mechanisms are arranged in parallel in such a way as to face each other across the upper mold1and the lower mold2.

The tilt rotating shaft10of the first main link member7ais held to the base frame17by a tilting rotation bearing9provided outside the first parallel link mechanism. The center of rotation of the tilt rotating shaft10of the first main link member7acoincides with the center of gravity of a rotation body including the closed or opened upper mold1and lower mold2, and the upper frame5and the lower frame6. Similarly, the tilt rotating shaft10of the second main link member7bis held to the base frame17by the tilting rotation bearing9provided outside the second parallel link mechanism. The center of rotation of the tilt rotating shaft10of the second main link member7bcoincides with the center of gravity of the rotation body including the closed or opened upper mold1and lower mold2, and the upper frame5and the lower frame6. Here, “coincide” is not limited to a case where both coincide completely, but includes a case where errors are contained due to a difference between the weight of the upper mold1and the weight of the lower mold2.

The rotation actuator16is disposed above the drive side support frame19. The rotation actuator16is provided in connection with one tilt rotating shaft10of the pair of main link members7. The rotation actuator16may be operated by any one of electric motor, hydraulic pressure and pneumatic pressure. An example of the rotation actuator16is an electric actuator. An example of the electric actuator is an electric motor such as a servo motor. The rotation actuator16functions as a drive unit separating the upper mold1from the lower mold2in the tilting or horizontal direction.

The upper mold1and the lower mold2are tilted when the rotation actuator16rotates the tilt rotating shaft10of the first main link member7aby 45° to 130° with the upper mold1and the lower mold2closed by the opening/closing mechanism21. The upper mold1is separated from the lower mold2in the horizontal direction when the rotation actuator16causes the tilt rotating shaft10of the first main link member7ato rotate by a predetermined angle with the upper mold1and the lower mold2closed by the opening/closing mechanism21. Separation of the upper mold1from the lower mold2in the horizontal direction is realized by the rotation actuator16causing the first parallel link mechanism to act. At this time, the second parallel link mechanism also acts in accordance with the movement of the first parallel link mechanism. Note that the second parallel link mechanism is not essential, but the upper frame5and the lower frame6may be connected by, for example, only the first parallel link mechanism and the second main link member7b, or the upper frame5and the lower frame6may be connected by only the first parallel link mechanism and the second sub-link member8b.

The ladle25is mounted at a top end part of the side face of the lower mold2. A storage part for storing molten metal is defined in the ladle25. A pouring port25a(seeFIG. 6) of the ladle25is connected to a receiving port2aof the lower mold2(seeFIG. 6).

FIG. 3is a diagram illustrating cross sections of the upper mold and the lower mold inFIG. 1. Here, a state is shown in which a plurality of cores34are fitted on a top surface of the lower mold2. As shown inFIG. 3, the casting apparatus50is provided with a pushing out mechanism37including a pushing out plate28(upper pushing out plate), a pair of pushing out pins26(upper pushing out pin), a pair of return pins27and a plurality of push rods (regulating member)29. The pushing out mechanism37is provided in the upper frame5.

The pushing out plate28is disposed in an inner space formed in the interior on a top end side of the upper mold1. The pushing out plate28is fitted in the inner space in such a way as to be freely movable up and down. Each pushing out pin26is provided on an undersurface of the pushing out plate28. Each pushing out pin26moves up and down through a hole from the inner surface of the upper mold1to a cavity (upper cavity) in which a casting is formed. Each pushing out pin26pushes out the casting in the cavity by a distal end thereof. Each return pin27is provided at a position of the pushing out plate28different from the pushing out pin26of the undersurface. Each return pin27moves up and down through the hole from the inner space of the upper mold1to an undersurface of the upper mold1. Each return pin27causes the pushing out plate28to move up when the distal end of the return pin27abuts against the top surface of the lower mold2in a process in which the upper mold1and the lower mold2are closed.

Each push rod29is provided on the undersurface of the upper frame5. Each push rod29is disposed on the undersurface of the upper frame5by penetrating the upper mold die base3. The distal end of each push rod29is disposed above the pushing out plate28into the inner space with each push rod29inserted into the hole from the top surface of the upper mold1to the inner space. The length of each push rod29is set to a length at which the pushing out plate28is pushed down when the first actuator22is contracted and the upper mold1reaches an ascending end. Note that the ascending end is a highest possible position of the upper mold1as the first actuator22is contracted. That is, each push rod29passes through the hole from the top surface of the upper mold1into the inner space formed at a position above the upper mold1entering the inner space by a predetermined length to thereby prevent the pushing out plate28from moving up.

The lower frame6incorporates a second actuator30. The second actuator30may be operated by any one of electric motor, hydraulic pressure and pneumatic pressure. An example of the second actuator30is a hydraulic cylinder. A top end part of the second actuator30is mounted on an undersurface of the pushing out member31. A pair of left and right guide rods32passes through guide cylinders33attached to the lower frame6and is mounted on the undersurface of the pushing out member31.

Just like the upper mold1, the lower mold2incorporates the pushing out plate28(lower pushing out plate) connecting the pair of pushing out pins26(lower pushing out pins) and the pair of return pins27. There is such a positional relationship in the lower mold2that the pushing out member31moves up by extending operation of the second actuator30to push up the pushing out plate28and the pair of pushing out pins26and the return pins27move up. The distal end of each pushing out pin26pushes out a casting in a cavity (lower cavity). Note that the return pins27of the upper mold1and the lower mold2are pushed back at the time of mold closing, by a mating surface of the mold opposite to the distal ends of the return pins27or the distal ends of the opposite return pins27. Accordingly, the pushing out pin26connected to the pushing out plate28is also pushed back. At the time of mold closing, contraction operation of the second actuator30causes the pushing out member31to reach a descending end position. Note that the descending end refers to a lowest possible position of the lower mold2as the second actuator30is contracted.

A pair of positioning keys35is mounted in the lower periphery (side face bottom end part) of the upper mold1. A pair of key grooves36is provided in the upper periphery (side face top end part) of the lower mold2in such a way as to be engageable with the pair of positioning keys35. The positioning keys35and the key grooves36constitute a positioning unit for positioning the upper mold1and the lower mold2in the horizontal direction. According to this positioning unit, since the upper mold1and the lower mold2are positioned in the horizontal direction, it is possible to prevent the upper mold1and the lower mold2from being displaced and closed.

Next, the configuration relating to driving of the casting apparatus50will be described in detail.FIG. 4is a block diagram of the configuration relating to driving of the casting apparatus50inFIG. 1. As shown inFIG. 4, the casting apparatus50is provided with a main controller60(control unit) and a hydraulic unit70.

The main controller60is hardware controlling the entire driving of the casting apparatus50. The main controller60is constructed of a general-purpose computer including a computation apparatus such as a CPU (Central Processing Unit), a storage apparatus such as a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive) and a communication apparatus or the like.

The main controller60is connected communicably with a first drive unit61, a second drive unit62and an optical sensor63. The main controller60outputs a control signal to the first drive unit61and the second drive unit62to control driving. The main controller60is connected to an operation panel (not shown) such as a touch panel and causes the first drive unit61and the second drive unit62to operate according to a command operation by an operator received by the operation panel. The main controller60can also cause the first drive unit61and the second drive unit62to operate with reference to a casting recipe stored in the storage apparatus.

The first drive unit61causes either the upper mold or the lower mold to move up and down to thereby open or close the upper mold1and the lower mold2. In the present embodiment, the first drive unit61causes the upper mold1to move up and down to perform mold closing or mold opening. As an example, the first drive unit61includes the hydraulic unit70, the first actuator22and the second actuator30.

The hydraulic unit70supplies hydraulic oil to the first actuator22and the second actuator30. The hydraulic unit70is provided with a hydraulic circuit. The hydraulic circuit is a channel that circulates hydraulic oil of the hydraulic actuator. The hydraulic circuit includes a hydraulic pump71(first hydraulic pump), an electric motor72(first pump electric motor), a solenoid valve (not shown), an oil tank (not shown) or the like. The hydraulic circuit supplies the hydraulic oil stored in the oil tank to the first actuator22and the second actuator30. The hydraulic circuit collects the hydraulic oil from the first actuator22and the second actuator30and returns the hydraulic oil to the oil tank. In this way, the hydraulic circuit can circulate the hydraulic oil.

The hydraulic pump71suctions the hydraulic oil in the oil tank and supplies the hydraulic oil to the first actuator22and the second actuator30. The electric motor72is a device driving the hydraulic pump and is, for example, a variable speed motor. The hydraulic oil is carried from the hydraulic pump according to the number of revolutions of the electric motor72. A discharge flow rate of the hydraulic pump is calculated by multiplying the number of revolutions of the electric motor72by the volume of the hydraulic pump.

The hydraulic unit70is provided with a drive control unit73(first drive control unit) controlling the number of revolutions of the electric motor72. The drive control unit73is a device controlling the number of revolutions of the electric motor72. The drive control unit73includes a converter circuit that converts AC to DC and an inverter circuit that performs inverter control. The inverter circuit controls ON/OFF operation of a switching element provided for the inverter circuit. As an example, the drive control unit73receives the number of revolutions (rotation speed) of the electric motor72detected by a number of revolutions sensor (not shown) and a target number of revolutions (target rotation speed) as input, performs proportional integration (PI) control, and thereby generates a current command value. The drive control unit73generates a control signal to perform ON/OFF operation of the switching element based on the current command value and outputs the control signal to the inverter circuit. The electric motor72is thereby controlled in such a way as to operate at a predetermined number of revolutions at predetermined timing.

The first drive unit61is connected to a power supply74and operates with power supplied from the power supply74. By outputting a control signal, the main controller60can shut off the power supply74from the first drive unit61. “Shutting off” means electrically shutting off a connection.

The second drive unit62causes the upper mold1and the lower mold2closed by the first drive unit61to tilt. The second drive unit62includes, for example, a rotation control unit80(second electric control unit) and the rotation actuator16. The rotation control unit80outputs a control signal to the rotation actuator16based on the control signal of the main controller60and performs position control of the rotation actuator16. The “position control” refers to controlling the angle of rotation and the rotation speed of the rotation actuator16by a control signal. When the rotation actuator16is an electric motor, power is not supplied when the rotation actuator16is not driving.

The second drive unit62is connected to a power supply81and operates with power supplied from the power supply81. By outputting a control signal, the main controller60can shut off the power supply81from the second drive unit62. “Shutting off” means electrically shutting off a connection.

The optical sensor63is a detector using light. The optical sensor63is disposed in the periphery of the casting apparatus50and detects an object. Details of the mounting position of the optical sensor63will be described later. The optical sensor63includes a light projecting unit and a light receiving unit. The optical sensor63detects, for example, that an operator passes between the light projecting unit and the light receiving unit. A specific example of the optical sensor63is a light curtain. The optical sensor63outputs the detection result to the main controller60.

When an object is detected by the optical sensor63, the main controller60shuts off the power supplies74and81of the first drive unit61and the second drive unit62. This causes the first drive unit61and the second drive unit62to lose power sources and stop operating. At this time, energy accumulated in the first drive unit61and the second drive unit62is released according to a predetermined procedure.

The main controller60performs an exceptional operation during a predetermined casting period. The “predetermined casting period” refers to a period after molten metal is supplied to the upper mold1and the lower mold2tilted by the second drive unit62until the molten metal is cooled. Supply start timing of the molten metal is, for example, timing at which a tilt start button is pressed. Alternatively, the supply start timing of the molten metal is timing at which the main controller60outputs a control signal for tilt start is outputted to the second drive unit62. Cooling ending timing of the molten metal is, for example, when a predetermined time has passed after start timing of pouring the molten metal. Alternatively, the cooling ending timing of the molten metal is timing at which temperature falls to or below a predetermined temperature based on the detection result by a sensor (not shown) detecting temperatures of the upper mold1and the lower mold.

During a predetermined casting period, if the first drive unit61is completely stopped, mold opening may occur before the molten metal hardens sufficiently and the molten metal may flow out of the metal die. During the predetermined casting period, if the second drive unit62is completely stopped, torque by the second drive unit may be released, the tilting position cannot be kept and pouring of the molten metal may be suspended. In this case, the molten metal may coagulate without a sufficient amount of molten metal being poured. When an insufficient amount of molten metal coagulates, the pushing out pin26may not be able to reach the casting. If such an event occurs, the operator may have to remove the casting from the metal die using a burner or the like. As described above, when the first drive unit61and the second drive unit62have completely stopped during the predetermined casting period, there is a risk of requiring considerable time for restoration.

For this reason, when the optical sensor63detects an object for the predetermined casting period, the main controller60does not shut off the power supply74of the first drive unit61and the second drive unit62, but causes the first drive unit61to continue mold closing and causes the second drive unit62to keep the tilting position. In this way, the casting apparatus50can be speedily restored even when it is stopped in emergency.

Next, an example of the casting method by the casting apparatus50will be described with reference toFIG. 5toFIG. 12.FIG. 5is a flowchart illustrating the casting method by the casting apparatus inFIG. 1.FIG. 6is a diagram viewed from an arrow direction of a line A-A inFIG. 1and for describing an apparatus starting state.FIG. 7is a diagram illustrating a second separate state in which the upper and lower molds are slid through operation of a parallel link mechanism and describing an initial state of a manufacturing step.FIG. 8is a diagram for describing a mold closed state in which the upper mold and the lower mold are closed.FIG. 9is a diagram in which the closed upper mold and lower mold are turned by 90°.FIG. 10is a diagram illustrating the upper mold raised up to a midway position.FIG. 11is a diagram illustrating the upper mold and the lower mold slid into a first separate state.FIG. 12is a diagram illustrating the upper mold raised up to an ascending end from the state inFIG. 11.

As shown inFIG. 5andFIG. 6, at the start of power supply, the upper mold1of the casting apparatus50is at an ascending end and the pair of main link members7and the pair of sub-link members8are perpendicular to the installation surface of the casting apparatus50(apparatus starting state: step S11). In step S11, the main power supply of the casting apparatus50is turned ON and the first drive unit61is connected to the power supply74in a conduction-enabled state. The electric motor72of the first drive unit61starts operation under the control of the main controller60. The second drive unit62is connected to the power supply81in a conduction-enabled state.

Note that the casting apparatus50is disposed between a workspace (not shown) and a pouring apparatus (not shown). The casting apparatus50is disposed such that the ladle25faces the workspace (not shown) in the Y direction. The workspace is a space for the operator to perform a core fitting operation or the like. The pouring apparatus is an apparatus that pours molten metal into the ladle25. For example, a conveyor (not shown) is disposed between the casting apparatus50and the workspace. The conveyor is an apparatus that carries a casting (cast product) cast by the casting apparatus50. The conveyor extends up to an apparatus in a post-process (e.g., product cooling apparatus, sand shakeout apparatus, product finishing apparatus or the like).

Next, as shown inFIG. 5andFIG. 7, the casting apparatus50is placed into an initial state of a series of casting processes (step S12). The casting apparatus50is changed from the state shown inFIG. 6to an initial state shown inFIG. 7. The main controller60of the casting apparatus50outputs a control signal to drive the rotation actuator16. In this way, the rotation actuator16is supplied with power and driven according to a command.

When the rotation actuator16is driven, the tilt rotating shaft10of the first main link member7aturns clockwise. In the present embodiment, a turn in the clockwise direction is assumed to be a right-hand turn and the opposite turn is assumed to be a left-hand turn. Accordingly, the upper mold1and the lower mold2slide in an arc in opposite directions through action of the parallel link mechanism. More specifically, when the mutually opposing upper mold1and lower mold2make circular motion of right-hand turn around the tilt rotating shaft10as a central axis, and the upper mold1and the lower mold2move away from each other in the horizontal direction. At this time, the upper mold1has moved to the pouring apparatus side (second separate state). This second separate state is an initial state of a series of casting steps. In the present embodiment, the state in which the lower mold2has moved to the pouring apparatus side is assumed to be a first separate state and the state in which the upper mold1has moved to the pouring apparatus side is assumed to be a second separate state. That is, the first separate state (seeFIG. 11) is a state in which the rotation actuator16causes the upper mold1to move in a direction away from the pouring apparatus and the lower mold2moves in a direction approaching the pouring apparatus, whereby the upper mold1and the lower mold2remain separate from each other in the horizontal direction. The second separate state (seeFIG. 7) is a state in which the rotation actuator16causes the upper mold1to move in the direction approaching the pouring apparatus and the lower mold2moves in a direction away from the pouring apparatus, whereby the upper mold1and the lower mold2remain separate from each other in the horizontal direction.

Next, the core34is fitted in a predetermined position of the lower mold2(step S13). Fitting of the core34is performed by, for example, the operator. The core34is molded using, for example, a core molding machine (not shown). In the second separate state, the lower mold2is open upward in which the ladle25mounted on the lower mold2is not in contact with the upper mold1. Since the lower mold2is open upward in this way, the core34can be fitted in the lower mold2safely.

Next, the casting apparatus50causes the rotation actuator16to drive the tilt rotating shaft10of the first main link member7ato turn counterclockwise and then return to the apparatus starting state inFIG. 6(step S14). The main controller60of the casting apparatus50outputs a control signal to drive the rotation actuator16. In this way, the rotation actuator16is supplied with power and driven according to a command.

Next, as shown inFIG. 5andFIG. 8, the casting apparatus50causes the first actuator22to extend to close the upper mold1and the lower mold2(step S15). The hydraulic unit70supplies hydraulic oil to the first actuator22. This causes the first actuator22to extend. At this time, the positioning key35of the upper mold1engages with the key groove36of the lower mold2, and the upper mold1and the lower mold2are fixed in the horizontal direction. Furthermore, mold closing prevents rotations of the pair of main link members7and the pair of sub-link members8, the main link upper rotating shaft11, the main link lower rotating shaft12, the sub-link upper rotating shaft13and the sub-link lower rotating shaft14, which integrates the upper mold1, the lower mold2, the upper frame5, the lower frame6, the pair of main link members7and the pair of sub-link members8together.

Next, when the upper mold1and the lower mold2are closed, that is, in a mold-closed state, the pouring apparatus supplies molten metal into the ladle25(step S16). Next, as shown inFIG. 5andFIG. 9, the casting apparatus50causes the rotation actuator16to drive the tilt rotating shaft10of the first main link member7ato turn counterclockwise by approximately 90° to bring the upper mold1and the lower mold2into a tilted state (step S17: start of casting period). The main controller60of the casting apparatus50outputs a control signal to drive the rotation actuator16. In this way, the rotation actuator16is supplied with power and driven according to a command. The sub-link central part rotating shaft15is thereby raised from the top surface of the base frame17on which it had been placed. Accordingly, the closed and integrated upper mold1, lower mold2, upper frame5, lower frame6, pair of main link members7and pair of sub-link members8rotate and the molten metal in the ladle25is tilted and poured into the cavity formed between the upper mold1and the lower mold2(step S18).

After the process in above step S18ends, the state inFIG. 9is kept for a predetermined time, waiting for the poured molten metal to coagulate (cool) (step S19: end of casting period). Note that as described above, the rotation actuator16is caused to drive the tilt rotating shaft10of the first main link member7ato turn counterclockwise by approximately 90°, but the tilt rotating shaft10may also be caused to turn by a predetermined angle within a range of 45° to 130° or 45° to 90°.

Next, the main controller60of the casting apparatus50causes the rotation actuator16to drive the tilt rotating shaft10of the first main link member7ato turn clockwise and return to the state inFIG. 8(step S20). The main controller60of the casting apparatus50outputs a control signal to drive the rotation actuator16. In this way, the rotation actuator16is supplied with power and driven according to a command.

Next, mold removal and mold opening from the lower mold2are simultaneously performed (step S21). Mold opening is performed as shown inFIG. 5andFIG. 10and mold removal from the lower mold2is also performed simultaneously. Mold opening is started by the casting apparatus50operating the first actuator22. The hydraulic unit70supplies hydraulic oil to the first actuator22in reverse direction. This causes the first actuator22to contract and causes the upper mold1to move up. Mold opening of the upper mold1and the lower mold2starts in this way. Extending operation of the second actuator30starts simultaneously with the contracting operation of the first actuator22. That is, the hydraulic unit70also supplies hydraulic oil to the second actuator30. When the second actuator30extends, the pushing out pin26(seeFIG. 3) incorporated in the lower mold2is pushed out. This causes the casting (not shown) consisting of coagulated molten metal in the upper mold1and the lower mold2to be removed from the lower mold2and remain held to the upper mold1. The casting apparatus50causes the upper mold1to move up to a predetermined position and mold opening is completed. The predetermined position is a position where the distal end of the push rod29is not in contact with the top surface of the pushing out plate28of the upper mold1. In other words, the predetermined position is a position where there is a gap between the distal end of the push rod29and the top surface of the pushing out plate28of the upper mold1.

Next, as shown inFIG. 5andFIG. 11, the casting apparatus50causes the rotation actuator16to drive the tilt rotating shaft10of the first main link member7ato turn counterclockwise (step S22). The main controller60of the casting apparatus50outputs a control signal to drive the rotation actuator16. In this way, the rotation actuator16is supplied with power and driven according to a command. Through the action of the parallel link mechanism, the casting apparatus50causes the upper mold1and the lower mold2to slide in an arc and separates them apart in the horizontal direction. At this time, a state in which the upper mold1has moved to the conveyor side, that is, a first separate state in which the lower mold2has moved in a direction approaching the pouring apparatus. The angle of left-hand turn of the rotation actuator16at this time becomes on the order of 30° to 45° at which the upper mold1is opened downward.

Next, as shown inFIG. 5andFIG. 12, the casting apparatus50contracts the first actuator22to move the upper mold1up to an ascending end. The hydraulic unit70supplies hydraulic oil to the first actuator22in a reverse direction. When the hydraulic oil is supplied, the first actuator22extends. In this way, the distal end of the push rod29relatively pushes out the pushing out pin26(seeFIG. 6) with respect to the upper mold1via the pushing out plate28incorporated in the upper mold1. As a result, the casting held to the upper mold1is removed from the upper mold1(step S23). The casting removed from the upper mold1drops and is received by the conveyor provided below the upper mold1. That is, the conveyor functions as a receiver receiving the casting as well. After that, the casting is carried by the conveyor to, for example, a product cooling apparatus, a sand shakeout apparatus and a product finishing apparatus carrying out deburring or the like.

Next, as shown inFIG. 5, the casting apparatus50causes the rotation actuator16to drive the tilt rotating shaft10of the first main link member7ato turn clockwise (step S22). The main controller60of the casting apparatus50outputs a control signal to drive the rotation actuator16. The rotation actuator16is supplied with power and driven according to a command. In this way, the casting apparatus50returns to the initial state (FIG. 7). As described above, a series of casting processes are completed and a casting is cast by the casting apparatus50. When the casting processes are consecutively performed, castings can be cast consecutively by repeating processes from the core setting process in step S13.

Next, the emergency stop method for the casting apparatus50will be described. First, the mounting position of the optical sensor63will be described.FIG. 13is a perspective view illustrating a mounting position of the optical sensor of the casting apparatus. As shown inFIG. 13, two fixed type guards100are provided in the periphery of the casting apparatus50in such a way as to face each other across the casting apparatus50. The two fixed type guards100are arranged on sides of the casting apparatus50. For this reason, the front and the rear of the casting apparatus50are accessible. The operator passes through an entrance100aon the front of the casting apparatus50to set the cores or the like. The pouring apparatus passes through an entrance100bon the rear side of the casting apparatus50for pouring operation. The optical sensor63is provided at the entrance100aon the front of the casting apparatus50. The optical sensor63detects that the operator goes in the entrance100aon the front of the casting apparatus50.

FIG. 14is a schematic view illustrating the mounting position of the optical sensor of the casting apparatus. As shown by a state A inFIG. 14, when the casting apparatus50is in a second separate state, there is a first distance L1between the optical sensor63and the casting apparatus50. As shown by a state B inFIG. 14, when the casting apparatus50is in a tilting state, there is a second distance L2between the optical sensor63and the casting apparatus50. As shown by a state C inFIG. 14, when the casting apparatus50is in a first separate state, there is a third distance L3between the optical sensor63and the casting apparatus50. The first distance L1, the second distance L2and the third distance L3are set in such a way as to prevent the casting apparatus50from interfering with the optical sensor. Furthermore, the first distance L1, the second distance L2and the third distance L3are set to distances satisfying a predetermined safety standard (e.g., ISO13855 Safe Distance Standard).

FIG. 15is a flowchart illustrating an emergency stop method. The flowchart shown inFIG. 15is executed by the main controller60at timing at which a power supply to the casting apparatus50is turned ON.

The main controller60determines whether or not the operator is detected as a detection determination process (step S30). The main controller60determines whether or not the operator is detected based on the detection result of the optical sensor63.

When it is determined that the operator is detected (step S30: YES), the main controller60determines whether or not the detection timing at which the operator is detected is included in the casting period as a period determination process (step S31). For example, the main controller60determines a start of the casting period based on timing of pressing a tilt start button or timing of outputting a tilt start control signal. The main controller60determines an end of the casting period based on an elapsed time from the tilt start or a mold temperature. The main controller60determines whether or not detection timing (detection time) of the optical sensor63is included in the casting period.

When it is determined that the detection timing is not included in the casting period (step S31: NO), the main controller60performs first stop processing of shutting off the power supplies74and81of the first drive unit61and the second drive unit62as a first stop processing process (step S32). The main controller60operates a switch for shutting off electrical connections between the first drive unit61and the second drive unit62and power supplies74and81.

When it is determined that the detection timing is included in the casting period (step S31: YES), the main controller60performs second stop processing without shutting off the power supplies74and81of the first drive unit61and the second drive unit62but causing the first drive unit61to continue mold closing and causing the second drive unit62to hold the tilting position as a second stop processing process (step S33).

When it is determined that the operator is not detected (step S30: NO), if the first stop processing process (step S32) or the second stop processing process (step S33) ends, the flowchart shown inFIG. 15ends. After that, the main controller60executes the flowchart shown inFIG. 15from the beginning until termination conditions are satisfied.

Note that when the second stop processing process (step S33) ends and the casting period ends, the main controller60accepts operation of a temporary stop cancellation button by the operator. Upon accepting the operation of the temporary stop cancellation button, the main controller60resumes casting from the stopped state in the second stop processing process.

As described so far, according to the casting apparatus50of the first embodiment, when the optical sensor63detects the operator (object), the power supplies74and81of the first drive unit61and the second drive unit62are shut off. Thereby, operations of the first drive unit61and the second drive unit62are completely stopped. On the other hand, when the operations of the first drive unit61and the second drive unit62are completely stopped during the casting period after molten metal is supplied to the upper mold1and the lower mold2tilted by the second drive unit62until the molten metal is cooled, there is a possibility that the molten metal may not be supplied sufficiently in the metal die without being able to hold the tilting positions, may coagulate in such a state, making it difficult to remove the molten metal from the metal die or the metal die may be opened without the molten metal coagulating sufficiently. If such a situation occurs, it takes time to recover. For this reason, when the optical sensor63detects an operator during the above casting period, the casting apparatus50does not shut off the power supplies74and81of the first drive unit61and the second drive unit62, but the first drive unit61continues mold closing and the second drive unit62holds the tilting position. It is thereby possible to prevent the molten metal from coagulating when its amount is insufficient or prevent the metal die from opening, and so it is possible to speedily restore the apparatus even when it is stopped in emergency.

According to the casting apparatus50, when the optical sensor63detects an operator during the above casting period, the power supply to the first drive unit61is not shut off, the hydraulic pump71continues driving, and torque by the first actuator is kept, and so mold closing can be continued. Furthermore, according to the casting apparatus50, when the optical sensor63detects an operator during the above casting period, the power supply to the second drive unit62is not shut off and the torque by the rotation actuator16is kept, and it is thereby possible to keep the tilting position. To start the second drive unit with the power shut off, it is necessary to perform a positioning operation and perform origin returning processing to determine a reference position. According to the casting apparatus50, since no origin returning processing is necessary, time required for returning can be avoided.

Second Embodiment

FIG. 16is a front view of a casting apparatus according to a second embodiment. As shown inFIG. 16, a casting apparatus50A according to the second embodiment is different from the casting apparatus50according to the first embodiment mainly in that the opening/closing mechanism21moving the lower mold2up and down is provided in the lower frame6. Thus, the lower mold2of the casting apparatus50A can move up and down. Hereinafter, differences between the casting apparatus50A according to the second embodiment and the casting apparatus50according to the first embodiment will be described mainly and common description thereof will be omitted.

FIG. 17is a diagram illustrating cross sections of the upper die and the lower die inFIG. 16. As shown inFIG. 17, in the casting apparatus50A, the second actuator30is provided in the upper frame5and the pushing out mechanism37is provided in the lower frame6. In the casting apparatus50A, the pushing out plate28is disposed in an inner space formed in the interior on the bottom end side of the lower mold2. Each pushing out pin26is provided on the top surface of the pushing out plate28. Each pushing out pin26moves up and down through a hole from the inner space of the lower mold2to a cavity in which a casting is formed. A distal end of each pushing out pin26pushes out the casting in the cavity. Each return pin27is provided at a position different from the pushing out pin26at the top surface of the pushing out plate28. Each return pin27moves up and down through the hole from the inner space of the lower mold2to the top surface of the lower mold2. In a process in which the upper mold1and the lower mold2are closed, the distal end of each return pin27is abutted against the undersurface of the upper mold1to thereby cause the pushing out plate28to move down.

Each push rod29is provided on the top surface of the lower frame6. Each push rod29is disposed on the top surface of the lower frame6by penetrating the lower mold die base4. Each push rod29is inserted into a hole penetrating from the undersurface of the lower mold2to the inner space and the distal end of each push rod29is disposed below the pushing out plate28in the inner space. The length of each push rod29is set to a length that the pushing out plate28is pushed up when the first actuator22is contracted and the lower mold2becomes a descending end. That is, each push rod29passes through the hole penetrating an inner space formed at a lower position of the lower mold2from the undersurface of the lower mold2and enters the inner space by a predetermined length to prevent the pushing out plate28from moving down. The rest of the configuration is the same as that of the casting apparatus50according to the first embodiment.

According to the casting method for the casting apparatus50A, in above step S21, mold removal from the upper mold1and mold opening are performed in parallel. More specifically, the casting apparatus50A causes the lower mold2to move down through the opening/closing mechanism21provided in the lower frame6and starts mold opening of the upper mold1and the lower mold2. Simultaneously with this, the casting apparatus50A starts extending operation of the second actuator30provided in the upper frame5. Extension of the second actuator30causes the pushing out pin26incorporated in the upper mold1to be pushed out. In this way, a casting (not shown) made of molten metal coagulating in the upper mold1and the lower mold2is removed from the upper mold1and held to the lower mold2. In above process S23, mold removal from the lower mold2is performed. More specifically, the opening/closing mechanism21causes the lower mold2to move down to a descending end. Thus, the distal end of the push rod29relatively pushes out the pushing out pin26with respect to the lower mold2via the pushing out plate28incorporated in the lower mold2. As a result, the casting held to the lower mold2is removed from the lower mold2.

The casting apparatus50A exerts the same effects as those of the aforementioned casting apparatus50.

The respective embodiments have been described so far, but the present disclosure is not limited to the above respective embodiments. For example, instead of the second actuator30removing a casting from the upper mold1or the lower mold2, the pushing out plate28may be pushed out using a spring. In that case, at the time of mold closing of the upper mold1and the lower mold2, the return pin27of the lower mold2is pressed down by the upper mold1and the pushing out pin26is lowered, in which a mold closing force is offset by the pressing force of the return pin27, but it is possible to reduce the number of actuators.

It is possible to provide more than one casting apparatus50. At this time, there is no limit to an arrangement of the casting apparatus as long as the pouring apparatus can pour molten metal. The core may be fitted not only by the operator but also by a core fitting robot provided with articulated arms. The opening/closing mechanism21may cause both the upper mold1and the lower mold2to move up and down.

The first actuator22is not limited to a hydraulic actuator but may also be an electric actuator. For example, the first actuator22may be constructed of an electric cylinder and a drive control unit (first electric control unit).

The rotation actuator16is not limited to an electric actuator, but may be a hydraulic actuator such as a hydraulic motor. For example, the rotation actuator16may be connected to the hydraulic unit. The hydraulic circuit of the hydraulic unit may include a hydraulic pump (second hydraulic pump), an electric motor (second pump electric motor), a solenoid valve (not shown), an oil tank (not shown) or the like. The hydraulic unit may be provided with a drive control unit (second drive control unit) controlling the number of revolutions of the electric motor.

REFERENCE SIGNS LIST