Casting molding device and casting manufacturing method

Abstract

To perform evaluation of a quality of a casting, with high accuracy.SOLUTION: A casting molding device, which is provided with a cavity formed by a fixed die and a movable die and an injection cylinder that is driven by hydraulic oil to inject molten metal into the cavity, and obtains a casting through an injecting step of injecting the molten metal into the cavity and a pressure-boosting step of pressure-boosting the injected molten metal, is further provided with: a pressure-boosting starting part that outputs a pressure-boosting start instruction indicating an instruction for starting the pressure-boosting step; a pressure information obtaining part that obtains pressure of the molten metal, on the basis of oil pressure in the injection cylinder; and a time measuring part that measure a time elapsing after the pressure-boosting starting instruction is outputted, where a pressure reference value is preliminarily set on pressure of the molten metal in the pressure-boosting step. The time measuring part measures a pressure reference value-arrival time during which the pressure-boosting starting instruction is outputted and then pressure of the molten metal arrives at the pressure reference value.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a casting molding apparatus and a method for producing a casting. [Background technology]

[0002] Patent Document 1 discloses a die-casting machine that has a fixed mold and a movable mold, and that forms a casting product by injecting molten metal into a cavity formed by the fixed mold and the movable mold using the extrusion force of a plunger that slides inside a sleeve. After the molten metal fills the cavity, the control device included in this die-casting machine predicts the occurrence of defects in the casting product based on the rise time of the pressure that the plunger applies to the molten metal and the stable value of the pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-157641 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a casting molding apparatus and a casting manufacturing method that are capable of evaluating the quality of castings with high accuracy. [Means for solving the problem]

[0005] [1] A casting molding apparatus comprising a fixed mold, a movable mold, a cavity formed by the fixed mold and the movable mold, and an injection cylinder driven by hydraulic oil for injecting molten metal into the cavity, the casting molding apparatus producing a cast product through an injection process for injecting the molten metal into the cavity and a pressure increase process for increasing the pressure of the injected molten metal, the casting molding apparatus comprising: a pressure increase start unit that outputs a pressure increase start command indicating a command to start the pressure increase process; a pressure information acquisition unit that acquires the pressure of the molten metal based on the hydraulic pressure in the injection cylinder; and a time measurement unit that measures the time from when the pressure increase start command is output, wherein a pressure reference value is set in advance for the pressure of the molten metal in the pressure increase process, and the time measurement unit measures the time until the pressure of the molten metal reaches the pressure reference value, from when the pressure increase start command is output until

[0006] [2] The casting molding apparatus described in [1] above further comprises a judgment unit for judging whether the casting is good or bad, wherein a target value is set in advance for the pressure reference value arrival time, and the judgment unit judges whether the casting is good or bad based on the deviation between the measured pressure reference value arrival time and the target value.

[0007] [3] In the casting molding apparatus described in [2] above, the judgment unit is characterized in that it classifies the casting as a good product when the deviation between the pressure reference value arrival time and the target value is within a predetermined range.

[0008] [4] A method for producing a casting using a casting molding device provided with a fixed mold, a movable mold, a cavity formed by the fixed mold and the movable mold, and an injection cylinder driven by hydraulic oil for injecting molten metal into the cavity, the method comprising: an injection process for injecting the molten metal into the cavity; a pressure increase process for increasing the pressure of the injected molten metal; a pressure increase start process for outputting a pressure increase start command indicating a command to start the pressure increase process; a pressure acquisition process for acquiring the pressure of the molten metal based on the oil pressure in the injection cylinder; and a time measurement process for measuring the time from when the pressure increase start command is output, wherein a pressure reference value is set in advance for the pressure of the molten metal in the pressure increase process, and the time measurement process measures the time it takes for the pressure of the molten metal to reach the pressure reference value, from when the pressure increase start command is output until the pressure of the molten metal reaches the pressure reference value. [Effects of the Invention]

[0009] According to the present disclosure, a casting molding apparatus and a casting manufacturing method are provided that are capable of evaluating the quality of a casting with high accuracy. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an example of a casting apparatus. [Figure 2] FIG. 2 is a block diagram illustrating an example of a functional configuration of the control device. [Figure 3] FIG. 3 is a block diagram illustrating an example of a hardware configuration of the control device. [Figure 4] FIG. 4 is a flowchart showing an example of a process flow relating to a process for obtaining a casting. [Figure 5] FIG. 5 is a flowchart showing an example of a processing flow relating to quality evaluation of a casting. [Figure 6] FIG. 6 is a graph showing an example of the results of measuring the pressure of the molten metal. [Figure 7] FIG. 7 is a graph showing an example of the results of measuring the pressure of the molten metal. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment will be described below with reference to the drawings. In the description, the same elements or elements having the same functions are designated by the same reference numerals, and redundant description will be omitted.

[0012] [Casting molding equipment] FIG. 1 schematically shows a casting molding apparatus 1 according to one embodiment. The casting molding apparatus 1 is an apparatus for producing a casting by filling a mold with molten metal (hereinafter referred to as "molten metal") and molding it. The molten metal is, for example, an aluminum alloy. The casting molding apparatus 1 is also referred to as a die-casting machine or die-casting apparatus. The casting molding apparatus 1 includes, for example, a casting section 10, an injection section 20, an injection cylinder 30, a hydraulic drive section 40, a position sensor 48, a pressure sensor 49, and a control device 50. Each element of the casting molding apparatus 1 will be described below.

[0013] (Casting Department) The casting section 10 is a section where a cavity having a shape corresponding to the cast product is formed by a pair of molds. The casting section 10 has a fixed mold 11 and a movable mold 12. The fixed mold 11 and the movable mold 12 are attached to a mold clamping device, and the fixed mold 11 and the movable mold 12 are clamped together by driving the movable mold 12 with a drive unit connected to the movable mold 12. Clamping the fixed mold 11 and the movable mold 12 forms a cavity 13 having a shape corresponding to the cast product and a runner 14 communicating with the cavity 13.

[0014] Cavity 13 is connected to injection section 20 via runner 14 (runner 14 and gate), and molten metal is filled into cavity 13. Thus, casting molding apparatus 1 is provided with stationary mold 11, movable mold 12, and cavity 13. Casting molding apparatus 1 obtains a cast product through an injection process in which molten metal is injected into cavity 13, and a pressure increase process in which the injected molten metal is increased in pressure.

[0015] (Injection part) The injection part 20 is a part that injects the molten metal into the cavity 13. The molten metal is injected by the injection part 20, thereby filling the cavity 13 with the molten metal. The injection part 20 has an injection sleeve 21, a plunger 22, and a plunger rod 23.

[0016] The injection sleeve 21 is a member that forms a space for temporarily storing molten metal. The injection sleeve 21 is formed, for example, in a cylindrical shape that extends horizontally in one direction. The injection sleeve 21 is provided with a pouring port 24. The casting molding apparatus 1 supplies the molten metal from the pouring port 24 into the injection sleeve 21 using a molten metal supply device or the like.

[0017] The plunger 22 is a member that moves the molten metal supplied inside the injection sleeve 21 toward the cavity 13. The plunger 22 is also referred to as a plunger tip. The plunger 22 is provided inside the injection sleeve 21 so as to be able to advance and retreat (move). In the present disclosure, with regard to the movement of the plunger 22, the direction in which the plunger 22 approaches the cavity 13 is referred to as "forward" or "forward," and the movement of the plunger 22 moving forward is referred to as "advancing." Furthermore, the direction in which the plunger 22 moves away from the cavity 13 is referred to as "rear" or "rearward," and the movement of the plunger 22 moving backward is referred to as "retreating," and the forward and rearward movements are collectively referred to as "advancing and retreating." In FIG. 1 , the front (forward) direction is represented by an arrow marked with "F," and the rear (rear) direction is represented by an arrow marked with "B."

[0018] As the plunger 22 moves forward, the molten metal in the injection sleeve 21 is injected (injected and filled) into the cavity 13 via the runner 14. As the plunger 22 moves backward, the molten metal is supplied from the pouring port 24 into the injection sleeve 21, with the plunger 22 positioned behind the pouring port 24.

[0019] (injection cylinder) The injection cylinder 30 is a member driven by hydraulic oil and injects the molten metal into the cavity 13. The injection cylinder 30 operates the plunger 22 of the injection part 20 to inject the molten metal into the cavity 13. The injection cylinder 30 is a hydraulically driven cylinder. The injection cylinder 30 has a cylinder container 31, a cylinder rod 32, a connecting part 33, and a cylinder head 34.

[0020] The cylinder container 31 forms a space for some of the members included in the injection cylinder 30 to move forward and backward. The cylinder container 31 is formed, for example, in a cylindrical shape so as to extend along the front-to-rear direction in which the plunger 22 operates. The front end (tip) of the cylinder rod 32 is detachably connected to the plunger rod 23 of the injection unit 20 via a connecting part 33. A cylinder head 34 is connected to the rear end of the cylinder rod 32, and the cylinder rod 32 and the cylinder head 34 are integrated.

[0021] A space is formed inside the cylinder container 31 behind the cylinder head 34, and this space is referred to as the "head-side hydraulic chamber 34a." A space is formed inside the cylinder container 31 forward of the cylinder head 34, and this space is referred to as the "rod-side hydraulic chamber 32a." By controlling the flow of hydraulic oil to each of the rod-side hydraulic chamber 32a and the head-side hydraulic chamber 34a, the speed (injection speed) of the plunger 22 during its forward movement and the speed during its backward movement may be controlled.

[0022] The injection cylinder 30 may have a speed adjustment valve 35. The speed adjustment valve 35 is a valve for controlling the speed of the plunger 22. The speed adjustment valve 35 adjusts the amount of hydraulic oil discharged from the rod-side hydraulic chamber 32a by adjusting its opening degree. The speed of the plunger 22 is controlled by adjusting the amount of hydraulic oil discharged from the rod-side hydraulic chamber 32a (i.e., meter-out control is performed). Instead of or in addition to meter-out control, the speed of the plunger 22 may be adjusted by adjusting the amount of hydraulic oil supplied to the head-side hydraulic chamber 34a (i.e., meter-in control may be performed).

[0023] (Hydraulic drive unit) The hydraulic drive unit 40 is a part that supplies hydraulic oil for operating the plunger 22 and hydraulic oil for increasing the pressure of the molten metal in the cavity 13 to the injection cylinder 30. The supply of these hydraulic oils to the injection cylinder 30 drives the injection cylinder 30. The hydraulic drive unit 40 has, for example, an accumulator 41, an accumulator 42, and a switching valve 43.

[0024] The accumulator 41 is a device that delivers hydraulic oil to the injection cylinder 30 in the injection process to operate the plunger 22. The accumulator 41 includes, for example, a sealed container 41a, a hydraulic oil chamber 41b, a gas chamber 41c, and an airtight member 41d. The sealed container 41a forms spaces that become the hydraulic oil chamber 41b and the gas chamber 41c, and houses the airtight member 41d. The hydraulic oil chamber 41b stores hydraulic oil. The gas chamber 41c stores pressurized gas. The airtight member 41d is movably disposed within the sealed container 41a and airtightly separates the hydraulic oil chamber 41b and the gas chamber 41c.

[0025] The hydraulic oil chamber 41b of the accumulator 41 is connected to the head-side hydraulic chamber 34a of the injection cylinder 30. When pressurized gas is supplied to the gas chamber 41c, the airtight member 41d is pressed and moved. As the airtight member 41d moves, hydraulic oil for injection is supplied from the hydraulic oil chamber 41b to the head-side hydraulic chamber 34a.

[0026] The accumulator 42 is a device that delivers hydraulic oil to the injection cylinder 30 to apply pressure to the molten metal in the cavity 13 by driving the plunger 22 during the pressure-increasing process. The accumulator 42 includes, for example, a sealed container 42a, a hydraulic oil chamber 42b, a gas chamber 42c, and an airtight member 42d. The sealed container 42a forms spaces that become the hydraulic oil chamber 42b and the gas chamber 42c, and houses the airtight member 42d. The hydraulic oil chamber 42b stores hydraulic oil. The gas chamber 42c stores pressurized gas. The airtight member 42d is movably disposed within the sealed container 42a and airtightly separates the hydraulic oil chamber 42b and the gas chamber 42c.

[0027] The hydraulic oil chamber 42b of the accumulator 42 is connected to the head-side hydraulic chamber 34a of the injection cylinder 30. When pressurized gas is supplied to the gas chamber 42c, the airtight member 42d is pressed and moved. As the airtight member 42d moves, hydraulic oil for boosting pressure is supplied from the hydraulic oil chamber 42b to the head-side hydraulic chamber 34a.

[0028] The switching valve 43 is a member that switches between accumulators that supply hydraulic oil to the injection cylinder 30 (head-side hydraulic chamber 34a). The switching valve 43 switches between a state in which hydraulic oil for injection is supplied from the accumulator 41 to the injection cylinder 30, and a state in which hydraulic oil for boosting is supplied from the accumulator 42 to the injection cylinder 30. The switching valve 43 may be any valve that can switch between these two states. The switching valve 43 operates based on an operation command from the control device 50.

[0029] (position sensor) The position sensor 48 is a sensor that acquires information indicating the position of the plunger 22. The position of the plunger 22 may be the position of the tip of the plunger 22 in the front-rear direction in which the plunger 22 moves. The position sensor 48 is provided, for example, in the injection cylinder 30, and acquires information indicating the position of the plunger 22 by detecting the position of the connecting portion 33, the cylinder rod 32, or the cylinder head 34. The position sensor 48 may be provided in the injection unit 20 instead of the injection cylinder 30. The position sensor 48 may directly detect the position of the plunger 22, or may acquire information indicating the position of the plunger 22 by detecting the position of the plunger rod 23. The position sensor 48 outputs the detection result to the control device 50.

[0030] (Pressure sensor) The pressure sensor 49 is a sensor that measures the pressure in the head-side hydraulic chamber 34a. The pressure sensor 49 outputs the measurement result of the pressure in the head-side hydraulic chamber 34a to the control device 50. In one example, the injection force is obtained by multiplying the pressure in the head-side hydraulic chamber 34a by the cross-sectional area (cross-sectional area on the rear side) of the cylinder head 34. Then, the pressure applied to the molten metal in the cavity 13 (the pressure of the molten metal) is obtained by dividing the injection force by the cross-sectional area of ​​the plunger 22. In this case, since the values ​​other than the pressure of the head-side hydraulic chamber 34a are known, once the pressure of the head-side hydraulic chamber 34a is measured, the pressure of the molten metal in the cavity 13 is determined.

[0031] The control device 50 is a device that controls at least some of the elements included in the casting molding apparatus 1. The control device 50 is configured with one or more computers. The control device 50 controls the controlled objects to execute the processes for obtaining a casting, and also performs calculations to evaluate the quality of the obtained casting.

[0032] A monitor 52 may be connected to the control device 50. The monitor 52 is a device for outputting (displaying) the results of calculations performed by the control device 50 to the operator of the casting apparatus 1. The monitor 52 may be any device capable of displaying information, and may be, for example, a liquid crystal display.

[0033] 2, the control device 50 has, for example, as functional components (hereinafter referred to as "functional blocks"), a position information acquisition unit 62, an injection control unit 64, a pressure increase start unit 66, a pressure information acquisition unit 68, a time measurement unit 70, and a determination unit 72. The processes executed by these functional blocks correspond to the processes executed by the control device 50.

[0034] The position information acquiring unit 62 acquires the measurement results from the position sensor 48 as information indicating the position of the plunger 22. The position information acquiring unit 62 may repeatedly acquire the measurement results from the position sensor 48 at a predetermined cycle (every predetermined cycle). The injection control unit 64 controls the speed adjustment valve 35 in the injection process so that the speed of the plunger 22 follows the target speed. The injection control unit 64 may calculate the current speed of the plunger 22 from the measurement results from the position sensor 48.

[0035] The pressure increase start unit 66 outputs a pressure increase start command that indicates a command to start the pressure increase process. The pressure increase start unit 66 outputs the pressure increase start command, for example, when the position of the plunger 22 indicated by the measurement value by the position sensor 48 reaches a preset start position. In one example, the pressure increase start unit 66 outputs, as the pressure increase start command, a signal to the switching valve 43 to switch from a state in which the accumulator 41 and the injection cylinder 30 are connected to a state in which the accumulator 42 and the injection cylinder 30 are connected.

[0036] The pressure information acquisition unit 68 acquires the pressure of the molten metal based on the hydraulic pressure inside the injection cylinder 30. The pressure information acquisition unit 68 acquires the pressure of the molten metal at least during the pressure increasing process. The pressure information acquisition unit 68 acquires the pressure of the molten metal by calculating the pressure that the plunger 22 applies to the molten metal filled in the cavity 13, for example, from the value measured by the pressure sensor 49. The pressure of the molten metal calculated (acquired) by the pressure information acquisition unit 68 is also referred to as the casting pressure.

[0037] The time measurement unit 70 measures the time from when the pressure increase start command is output. Specifically, a pressure reference value is set in advance for the pressure of the molten metal in the pressure increase process, and the time measurement unit 70 measures the time from when the pressure increase start command is output until the pressure of the molten metal reaches the pressure reference value (hereinafter referred to as the "pressure reference value arrival time").

[0038] The determination unit 72 determines whether a casting is acceptable or unacceptable. Specifically, a target value is set in advance for the pressure reference value arrival time, and the determination unit 72 determines whether the casting is acceptable or unacceptable based on the discrepancy between the measured pressure reference value arrival time and the target value. That is, when determining whether a casting is acceptable or unacceptable and performing a quality evaluation, the determination unit 72 uses the pressure reference value arrival time in the pressure boosting process executed to obtain the casting. In one example, if the discrepancy (difference) between the pressure reference value arrival time and the target value falls within a predetermined range, the determination unit 72 determines the casting to be acceptable or unacceptable if the discrepancy (difference) falls outside the predetermined range.

[0039] 3 schematically shows the hardware configuration of the control device 50. The control device 50 includes, for example, a circuit 91. The circuit 91 includes a processor 92, a memory 93, a storage 94, an input / output port 95, and a timer 96. The storage 94 is configured with one or more non-volatile memory devices such as a flash memory or a hard disk. The storage 94 stores programs for configuring each of the above-mentioned functional blocks.

[0040] The memory 93 is composed of one or more volatile memory devices such as a random access memory. The memory 93 temporarily stores programs loaded from the storage 94. The processor 92 is composed of one or more arithmetic devices such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The processor 92 configures the above-mentioned functional blocks by executing the programs loaded into the memory 93. The results of calculations by the processor 92 are temporarily stored in the memory 93. The input / output port 95 inputs and outputs information to and from the position sensor 48, the speed adjustment valve 35, the switching valve 43, the pressure sensor 49, the monitor 52, etc. in response to a request from the processor 92. The timer 96 measures elapsed time by, for example, counting reference pulses at a fixed interval.

[0041] The hardware configuration of the control device 50 is not necessarily limited to configuring each functional block by a program. For example, each functional block of the control device 50 may be configured by a dedicated logic circuit or an ASIC (Application Specific Integrated Circuit) that integrates such logic circuits. The control device 50 may also be configured by multiple computers connected to each other so that they can communicate with each other.

[0042] [Casting manufacturing method] Next, a method for obtaining (manufacturing) a casting using the above-described casting molding apparatus 1 will be described as an example of a method for manufacturing a casting with reference to Figures 4 to 7. This method includes at least an injection step, a pressure increase step, a pressure increase start step, a pressure acquisition step, and a time measurement step. The injection step is a step of injecting molten metal into cavity 13. The pressure increase step is a step of increasing the pressure of the injected molten metal. That is, the pressure increase step is a step of increasing the pressure of the molten metal that has been injected and filled into cavity 13.

[0043] The pressure increase start process is a process of outputting the pressure increase start command, which indicates a command to start the pressure increase process. The pressure acquisition process is a process of acquiring the pressure of the molten metal in the cavity 13 based on the hydraulic pressure in the injection cylinder. The time measurement process is a process of measuring the time from when the pressure increase start command is output. A pressure reference value is set in advance for the pressure of the molten metal in the pressure increase process, and the time measurement process measures the time it takes for the pressure of the molten metal to reach the pressure reference value, from when the pressure increase start command is output until it reaches the pressure reference value.

[0044] 4 illustrates a series of processes executed by the control device 50 as a process flow for molding (manufacturing) one casting. The control device 50 executes step S11 with the plunger 22 placed in its initial position and the injection sleeve 21 being supplied with an amount of molten metal required to produce one casting. In step S11, for example, the injection control unit 64 starts a low-speed injection process. The low-speed injection process is a process in which the plunger 22 is operated at a slower speed than the high-speed injection process described below. In step S11, the injection control unit 64 controls the hydraulic drive unit 40 to start supplying hydraulic oil from the accumulator 41 to the head-side hydraulic chamber 34a of the injection cylinder 30.

[0045] After step S11 is executed, the position information acquisition unit 62 continues measurement by the position sensor 48. By executing step S11, the plunger 22 starts moving forward. As a result, the molten metal in the injection sleeve 21 starts moving toward the runner 14 and the cavity 13. In the low-speed injection process, the injection control unit 64 may adjust the aperture of the speed adjustment valve 35 so that the movement speed of the plunger 22 follows a target value. Note that in the low-speed injection process, the injection control unit 64 may control the speed of the plunger 22 by adjusting the amount of hydraulic oil supplied from the accumulator 41 to the head-side hydraulic chamber 34a, instead of or in addition to the aperture of the speed adjustment valve 35. The injection control unit 64 may calculate the movement speed of the plunger 22 from the measurement value of the position sensor 48 obtained by the position information acquisition unit 62.

[0046] Next, the control device 50 executes step S12. In step S12, for example, the injection control unit 64 waits until the plunger 22 reaches a preset first position. As a result, the low-speed injection process continues until the plunger 22 reaches the first position, and speed feedback control is executed so that the moving speed of the plunger 22 follows a target value. By continuing the low-speed injection process, most of the air that was present in the injection sleeve 21 together with the molten metal at the time step S11 was executed is discharged via the fixed mold 11 and the movable mold 12. The first position is set, for example, so that the movement of the plunger 22 to the first position prevents the molten metal from entering the cavity 13 and results in the entire area of ​​the runner 14 being filled with the molten metal.

[0047] Next, the control device 50 executes step S13. In step S13, for example, the injection control unit 64 executes a high-speed injection process. In step S13, the injection control unit 64 may control the hydraulic drive unit 40 so that a larger amount of hydraulic oil is supplied from the accumulator 41 to the head-side hydraulic chamber 34a than the amount of hydraulic oil supplied in the low-speed injection process.

[0048] By executing step S13, the plunger 22 moves forward at a faster speed. Then, the molten metal in the runner 14 and the injection sleeve 21 begins to be introduced into the cavity 13. In the high-speed injection process, the injection control unit 64 may adjust the aperture of the speed adjustment valve 35 so that the movement speed of the plunger 22 follows a target value. The target value (target range) of the movement speed of the plunger 22 in the high-speed injection process is set to be larger than the target value (target range) of the movement speed in the low-speed injection process. Note that in the high-speed injection process, the injection control unit 64 may control the speed of the plunger 22 by adjusting the amount of hydraulic oil supplied from the accumulator 41 to the head-side hydraulic chamber 34a instead of or in addition to the aperture of the speed adjustment valve 35.

[0049] Next, the control device 50 executes step S14. In step S14, for example, the injection control unit 64 waits until the plunger 22 reaches a preset second position. As a result, the high-speed injection process continues until the plunger 22 reaches the second position, and speed feedback control is executed so that the movement speed of the plunger 22 follows the target value. The second position is set, for example, so that the movement of the plunger 22 to the second position results in a state in which the molten metal fills the entire area of ​​the cavity 13. As described above, the injection process of injecting the molten metal into the cavity 13 includes a low-speed injection process and a high-speed injection process.

[0050] Next, the control device 50 executes step S15. In step S15, for example, the control device 50 controls the casting apparatus 1 to execute a pressure-increasing step. The pressure-increasing start unit 66 outputs a pressure-increasing start command to start the pressure-increasing step of step S15. The pressure-increasing start unit 66 may output a signal (pressure-increasing start command) to the switching valve 43 to stop the supply of hydraulic oil for injection from the accumulator 41 and to supply hydraulic oil for pressure-increasing from the accumulator 42 to the head-side hydraulic chamber 34a. This causes hydraulic oil for pressure-increasing to be supplied to the head-side hydraulic chamber 34a, and the force that tends to move the plunger 22 forward applies pressure to the molten metal in the cavity 13. After the start of execution of step S15, the accumulator 42 may supply hydraulic oil for pressure-increasing to the head-side hydraulic chamber 34a so that the pressure applied to the molten metal in the cavity 13 increases.

[0051] After the start of execution of step S15 or before the execution of step S15, the pressure information acquisition unit 68 may acquire measurement values ​​from the pressure sensor 49 and continue to calculate (acquire) the pressure applied to the molten metal in the cavity 13. The pressure information acquisition unit 68 may repeatedly calculate the pressure of the molten metal in the cavity 13 at a predetermined cycle (at every predetermined cycle).

[0052] Next, the control device 50 executes step S16. In step S16, for example, the control device 50 controls the casting apparatus 1 to execute a pressure holding process. The pressure holding process is a process for compensating for solidification shrinkage that occurs as the molten metal that has been injected and filled (injected and filled) into the cavity 13 cools and solidifies. In one example, the control device 50 applies a force to move the plunger 22 forward, thereby pressing the molten metal in the cavity 13 and applying a pressure holding pressure.

[0053] Next, the control device 50 executes step S17. In step S17, for example, the control device 50 controls the casting apparatus 1 to execute a cooling process. The cooling process is a process for cooling the casting formed in the cavity 13. The casting is obtained by executing the above series of processes. After the above series of processes are executed, the fixed mold 11 and the movable mold 12 may be opened and the casting may be removed. Then, the control device 50 may cause a molten metal supply device or the like to supply new molten metal into the injection sleeve 21, and then control the casting apparatus 1 to execute the series of processes of steps S11 to S17 again.

[0054] 5 shows a process flow for evaluating the quality of a casting, which is a series of processes executed by the control device 50 after the pressure increase step is completed. In this series of processes, the control device 50 first executes step S21. In step S21, for example, the timing unit 70 measures the pressure reference value arrival time, which indicates the time from when the pressure increase start command is output in step S15 until the pressure of the molten metal in the cavity 13 reaches the pressure reference value.

[0055] FIG. 6 shows a graph representing the change in pressure of the molten metal in the cavity 13 over time during a period that includes the execution period of the pressure increase process. In the graph in FIG. 6, the horizontal axis represents time, and the vertical axis represents the pressure of the molten metal in the cavity 13 (casting pressure). At time t1, a pressure increase start command is output, and the high-speed injection process is switched to the pressure increase process. In FIG. 6, the pressure reference value is represented by "Ps," and the time at which the pressure of the molten metal in the cavity 13 reaches the pressure reference value Ps is represented by "t2." The pressure reference value arrival time tr is the time (period) from time t1 to time t2.

[0056] The pressure reference value Ps is set, for example, based on the reference pressure during the period when the pressure increase substantially stops during the pressure increasing step. The reference pressure may be determined, for example, by actually operating the casting molding apparatus 1 multiple times in the initial stage of starting to produce a cast product using the casting molding apparatus 1. The pressure reference value Ps may be a value that is 85% to 95% of the reference pressure, and in one example, is a value that is 90% of the reference pressure.

[0057] Next, the control device 50 executes step S22. In step S22, for example, the determination unit 72 determines whether the casting being evaluated is a good product based on the deviation between the pressure reference value arrival time tr measured in step S21 and the target value. In one example, the determination unit 72 determines that the casting being evaluated is a good product if the deviation between the pressure reference value arrival time tr measured in step S21 and the target value is within a predetermined range. On the other hand, the determination unit 72 determines that the casting being evaluated is not a good product or is a defective product if the deviation between the pressure reference value arrival time tr measured in step S21 and the target value is outside the predetermined range.

[0058] Next, the control device 50 executes step S23. In step S23, for example, the determination unit 72 outputs the determination result of step S22. In one example, the determination unit 72 outputs information indicating the determination result of step S22 to the monitor 52. The determination unit 72 may cause the monitor 52 to display information indicating the determination result only when the determination result of step S22 determines that the casting being determined is not a conforming product or is a defective product. The control device 50 may execute the series of processes of steps S21 to S23 each time one casting is obtained by the series of processes shown in FIG. 4. The control device 50 may execute the series of processes of steps S21 to S23 during a period that overlaps with at least a portion of the period during which steps S17 and S18 are executed.

[0059] 7, the advantages of using the time at which the pressure reference value Ps is reached, starting from the start of the pressure-increasing process (time t1), as the base point, to determine whether the casting is acceptable or not will be explained. When the device supplying hydraulic oil to the head-side hydraulic chamber 34a switches from accumulator 41 to accumulator 42, some factors may cause a delay in the increase in pressure of the molten metal in the cavity 13. In this case, the delay in the increase in pressure may cause a portion of the molten metal in the cavity 13 to solidify, and even if the pressure increases, appropriate force may not be applied to the solidified portion. As a result, there is a concern that the air remaining in the molten metal may not be able to be reduced, which may degrade the quality of the casting.

[0060] In FIG. 7, "C1" represents the time change in the pressure of the molten metal in the graph shown in FIG. 6, and "C2" represents the time change in the pressure of the molten metal when there is a delay in the pressure increase. Conventionally, the "pressure increase time" is measured as the time from when the pressure reaches 40% of the reference pressure to when it reaches 90% of the reference pressure, assuming the reference pressure is 100%. In the pressure increase time C2, the time when the pressure reaches 40% of the reference pressure is indicated as "t0." The pressure increase time, which is the time from t0 to t2, is not significantly different from the pressure increase time C1, even if there is a delay in the pressure increase. Therefore, when the time change C2 shown in FIG. 7 is obtained, the casting being evaluated is determined to be a good product from the perspective of the pressure increase during the pressure increase process.

[0061] In contrast, when the series of processes shown in Figure 5 is executed and the pressure reference value arrival time tr is measured in the pressure change over time C2, the pressure reference value arrival time tr becomes a larger value than the pressure change over time C1 due to a delay in the pressure increase. This increases the possibility of observing changes caused by a delay in the pressure increase. As a result, the quality of the casting can be evaluated with high accuracy.

[0062] [Variations] The series of processes shown in each of Figures 4 and 5 are examples and can be modified as appropriate. In the series of processes described above, the control device 50 may execute one step and the next step in parallel, or may execute the steps in an order different from that of the example described above. The control device 50 may omit any step, or may execute a process in any step that is different from that of the example described above.

[0063] In step S23, the determination unit 72 may display on the monitor 52 the measurement result of the pressure reference value arrival time tr in step S21, in addition to the determination result in step S22. In step S23, the determination unit 72 may output information indicating the determination result in step S22 to a device that performs a process subsequent to the molding of the casting by the casting molding apparatus 1, instead of or in addition to the monitor 52. For example, if the determination unit 72 determines that the casting being judged is not a good product, it may send a signal indicating that the casting is not a good product to a device that sorts the castings. The device that sorts the castings may then sort the castings into those that are judged to be good products and those that are judged to be bad products.

[0064] Control device 50 may execute step S21 without executing step S22. Then, in step S23, control device 50 may display the measurement result of pressure reference value arrival time tr measured in step S21 on monitor 52. In this case, an operator of casting molding apparatus 1 may determine the quality of the cast product from pressure reference value arrival time tr displayed on monitor 52.

[0065] The casting apparatus 1 may include a pressure sensor that detects the pressure in the rod-side hydraulic chamber 32a, in addition to the pressure sensor 49. In this case, the pressure information acquisition unit 68 may calculate the pressure of the molten metal in the cavity 13 further based on the detected value of the pressure in the rod-side hydraulic chamber 32a.

[0066] In the above example, the control device 50 that controls the manufacturing process for forming a casting includes the pressure information acquisition unit 68, the time measurement unit 70, and the judgment unit 72. Alternatively, a computer for quality evaluation (quality evaluation device) separate from the control device 50 may include the pressure information acquisition unit 68, the time measurement unit 70, and the judgment unit 72.

[0067] The casting molding apparatus 1 may be configured in any manner as long as it is provided with a fixed mold, a movable mold, a cavity formed by the fixed mold and the movable mold, and an injection cylinder driven by hydraulic oil to inject molten metal into the cavity, and a casting can be obtained through the injection process and the pressure increasing process. In one of the various examples described above, at least some of the features described in the other examples may be combined.

[0068] Summary of this disclosure The casting molding apparatus 1 described above includes a fixed mold 11, a movable mold 12, a cavity 13 formed by the fixed mold 11 and the movable mold 12, and an injection cylinder 30 driven by hydraulic oil to inject molten metal into the cavity 13. The casting molding apparatus 1 produces a cast product through an injection process for injecting the molten metal into the cavity 13 and a pressure boosting process for increasing the pressure of the injected molten metal. The casting molding apparatus 1 also includes a pressure boost start unit 66 that outputs a pressure boost start command indicating a command to start the pressure boosting process, a pressure information acquisition unit 68 that acquires the pressure of the molten metal based on the hydraulic pressure in the injection cylinder 30, and a time measurement unit 70 that measures the time from when the pressure boost start command is output. A pressure reference value is set in advance for the pressure of the molten metal during the pressure boosting process. The time measurement unit 70 measures the pressure reference value arrival time tr, which is the time from when the pressure boost start command is output until the pressure of the molten metal reaches the pressure reference value Ps. According to this casting molding apparatus 1, the time tr to reach the pressure reference value is measured, and therefore, as described above, it is possible to perform a highly accurate evaluation of the quality of the casting.

[0069] The casting molding apparatus 1 described above may further include a determination unit 72 that determines the quality of the casting. A target value may be set in advance for the pressure reference value arrival time tr. The determination unit 72 may determine the quality of the casting based on the deviation between the measured pressure reference value arrival time tr and the target value. In this case, the casting molding apparatus 1 itself determines the quality of the casting based on the deviation, allowing for more accurate quality evaluation.

[0070] In the casting molding apparatus 1 described above, the judgment unit 72 may determine that the casting is acceptable when the deviation between the pressure reference value arrival time tr and the target value falls within a predetermined range. In this case, it is possible to determine whether the casting is acceptable by a simple calculation.

[0071] The above-described casting manufacturing method is a method for obtaining a casting using a casting molding apparatus 1 equipped with a fixed mold 11, a movable mold 12, a cavity 13 formed by the fixed mold 11 and the movable mold 12, and an injection cylinder 30 driven by hydraulic oil to inject molten metal into the cavity 13. This casting manufacturing method includes an injection process for injecting molten metal into the cavity 13, a pressure increase process for increasing the pressure of the injected molten metal, a pressure increase start process for issuing a pressure increase start command indicating a command to start the pressure increase process, a pressure acquisition process for acquiring the pressure of the molten metal based on the hydraulic pressure in the injection cylinder 30, and a time measurement process for measuring the time from the issuance of the pressure increase start command. A pressure reference value is set in advance for the pressure of the molten metal in the pressure increase process. In the time measurement process, the time required for the pressure of the molten metal to reach the pressure reference value is measured from the issuance of the pressure increase start command. This casting manufacturing method, like the casting molding apparatus 1, enables highly accurate quality evaluation of castings. [Explanation of symbols]

[0072] 1...casting molding device, 11...fixed mold, 12...movable mold, 13...cavity, 20...injection unit, 30...injection cylinder, 40...hydraulic drive unit, 48...position sensor, 49...pressure sensor, 50...control device, 66...pressure increase start unit, 68...pressure information acquisition unit, 70...time measurement unit, 72...judgment unit, Ps...pressure reference value, tr...pressure reference value arrival time.

Claims

1. A fixed mold; A movable mold; a cavity formed by the fixed mold and the movable mold; an injection cylinder driven by hydraulic oil to inject molten metal into the cavity; is established, a casting molding apparatus for obtaining a casting product through an injection step of injecting the molten metal into the cavity and a pressure increasing step of increasing the pressure of the injected molten metal, a pressure increase start unit that outputs a pressure increase start command indicating a command to start the pressure increase process; a pressure information acquisition unit that acquires the pressure of the molten metal based on the hydraulic pressure in the injection cylinder; a time measurement unit that measures the time since the pressure increase start command was output; Equipped with a pressure reference value is set in advance for the pressure of the molten metal in the pressure increasing step; The time measurement unit measures a time required for the pressure of the molten metal to reach the reference pressure value from when the pressure increase start command is output until the pressure of the molten metal reaches the reference pressure value. A casting molding device characterized by the above.

2. The casting molding apparatus according to claim 1, Further provided is a judgment unit for judging whether the casting is good or bad, A target value is set in advance for the pressure reference value arrival time, The determination unit determines whether the casting is good or bad based on the measured deviation between the reference pressure value arrival time and the target value. A casting molding device characterized by the above.

3. The casting molding apparatus according to claim 2, The determining unit determines the casting to be a non-defective product when a deviation between the pressure reference value arrival time and the target value falls within a predetermined range. A casting molding device characterized by the above.

4. A fixed mold; A movable mold; a cavity formed by the fixed mold and the movable mold; an injection cylinder driven by hydraulic oil to inject molten metal into the cavity; A casting manufacturing method for obtaining a casting using a casting molding apparatus provided with an injection step of injecting the molten metal into the cavity; a pressure increasing step of increasing the pressure of the injected molten metal; a pressure increase start process of outputting a pressure increase start command indicating a command to start the pressure increase process; a pressure acquiring step of acquiring a pressure of the molten metal based on a hydraulic pressure in the injection cylinder; a time measurement step of measuring the time since the pressure increase start command was output; Equipped with a pressure reference value is set in advance for the pressure of the molten metal in the pressure increasing step; In the time measurement step, a time required for the pressure of the molten metal to reach the reference pressure value is measured from when the pressure increase start command is output until the pressure of the molten metal reaches the reference pressure value. A casting manufacturing method characterized by the above.

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