Cast-molding apparatus

Abstract

To provide a cast-molding apparatus effective for further improving the quality of a die-cast product.SOLUTION: A cast-molding apparatus 1 includes a mold 10, a cavity 13 formed by the mold 10, injection means 20 that is driven by a hydraulic fluid and injects a molten metal into the cavity 13, control means 100 that controls an injection speed of the injection means 20, a die line L1 indicating a correlation between the injection speed and an injection force necessary for supplying the molten metal into the cavity 13, and a machine line L2 indicating a correlation between the injection speed and an injection force that can be generated by the injection means 20. The control means 100 is configured to generate a margin die line L1 obtained by shifting the die line L11 by a predetermined correction amount in a direction of increasing the injection output, specify an injection speed corresponding to an intersection between the margin die line L11 and the machine line L2 as a target injection speed, and accelerate the injection speed to the target injection speed and maintain the injection speed in the vicinity of the target injection speed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a casting molding apparatus. [Background technology]

[0002] Patent Document 1 discloses a method for determining the quality of a die casting based on the squared value of the molten metal flow rate during actual casting, by drawing a P-Q2 diagram under set casting conditions, and calculating the horizontal axis coordinate value of the process point, which is the intersection of the machine characteristic line and the mold characteristic line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-154193 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the quality of die casting is evaluated with a focus on the process point, but in actual casting, the responsiveness up to the time when the process point is reached also affects the quality of the die casting product.

[0005] The present disclosure provides a casting molding device that is effective in further improving the quality of die-cast products. [Means for solving the problem]

[0006] A casting molding apparatus according to one aspect of the present disclosure includes a mold, a cavity formed by the mold, an injection means driven by hydraulic oil to inject molten metal into the cavity, a control means for controlling the injection speed of the injection means, a die line indicating the correlation between the injection speed and the injection force required to supply the molten metal into the cavity, and a machine line indicating the correlation between the injection speed and the injection force that the injection means can generate, and the control means is configured to generate a margin die line by shifting the die line by a predetermined correction amount in a direction to increase the injection force, identify the injection speed corresponding to the intersection of the margin die line and the machine line as a target injection speed, accelerate the injection speed to the target injection speed, and maintain the injection speed near the target injection speed. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a casting molding device that is effective in further improving the quality of die-cast products. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating the configuration of a casting device. [Figure 2] FIG. 2 is a block diagram illustrating a functional configuration of a control device. [Figure 3] 1 is a graph illustrating a die line and a machine line. [Figure 4] 10 is a graph illustrating the transition of injection speed. [Figure 5] 10 is a graph showing a modified example of the control device. [Figure 6] FIG. 2 is a block diagram illustrating a hardware configuration of a control device. [Figure 7] 1 is a flowchart illustrating a casting molding procedure. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] [Casting molding equipment] FIG. 1 is a schematic diagram illustrating the configuration of a casting apparatus 1. The casting apparatus 1 is an apparatus that produces castings 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 apparatus 1 is also called a die-casting machine or a die-casting apparatus. The casting apparatus 1 includes, for example, a mold 10, an injection unit 20, a hydraulic drive unit 40, a position sensor 48, pressure sensors 51 and 52, and a control unit 100. Each element of the casting apparatus 1 will be described below.

[0011] (Mold) The mold 10 is a part that forms a cavity having a shape corresponding to the casting. The mold 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 casting and a runner 14 that communicates with the cavity 13.

[0012] Cavity 13 is connected to injection device 20 via runner 14 (runner 14 and gate), and molten metal is filled into cavity 13. Casting molding device 1 obtains a cast product through an injection process in which the molten metal is injected into cavity 13, and a pressure increase process in which the injected molten metal is increased in pressure.

[0013] (injection device) The injection device 20 (injection means) is driven by hydraulic oil and injects the molten metal into the cavity 13. The molten metal is injected by the injection device 20, thereby filling the cavity 13 with the molten metal. The injection device 20 has an injection sleeve 21, a plunger 22, a plunger rod 23, a plunger drive unit 30, and a hydraulic drive unit 40.

[0014] 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.

[0015] The plunger 22 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 "rearward" 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."

[0016] 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.

[0017] The plunger driving unit 30 is driven by hydraulic oil to advance and retract the plunger 22. The plunger driving unit 30 has a cylinder 31, a piston rod 32, a connecting portion 33, and a piston head .

[0018] The cylinder 31 is disposed rearward of the injection sleeve 21 and extends in the front-to-rear direction. The cylinder 31 may be a cylinder with a circular cross section. The piston rod 32 extends forward from within the cylinder 31. The front end (tip end) of the piston rod 32 is connected to the rear end (base end) of the plunger rod 23 of the injection device 20 via a connecting portion 33. The connecting portion 33 connects the piston rod 32 to the base end of the plunger rod 23 in a detachable manner. A piston head 34 is provided at the rear end (base end) of the piston rod 32.

[0019] The piston head 34 divides the interior of the cylinder 31 into a front space (hereinafter referred to as the "rod-side hydraulic chamber 32a") and a rear space (hereinafter referred to as the "head-side hydraulic chamber 34a"). Both the rod-side hydraulic chamber 32a and the head-side hydraulic chamber 34a contain hydraulic oil. The piston head 34 advances and retreats due to the differential pressure between the pressure of the hydraulic oil in the rod-side hydraulic chamber 32a and the pressure of the hydraulic oil in the head-side hydraulic chamber 34a. As the piston head 34 advances and retreats, the piston rod 32, the connecting portion 33, and the plunger rod 23 also advance and retreat. In this way, the piston head 34, the piston rod 32, the connecting portion 33, and the plunger rod 23 constitute the movable portion MP of the injection device 20.

[0020] The plunger drive unit 30 may have an adjustment valve 35. The adjustment valve 35 is a valve that adjusts the differential pressure. For example, the adjustment valve 35 may be configured to adjust the differential pressure by a meter-out system, in which the differential pressure is adjusted by adjusting the pressure of hydraulic oil in the rod-side hydraulic chamber 32a. For example, the adjustment valve 35 is provided in a hydraulic oil flow path that communicates with the rod-side hydraulic chamber 32a, and adjusts the pressure of hydraulic oil in the rod-side hydraulic chamber 32a by changing the opening of that flow path. The adjustment valve 35 may be configured to adjust the differential pressure by a meter-in system, in which the differential pressure is adjusted by adjusting the pressure of hydraulic oil in the head-side hydraulic chamber 34a.

[0021] The hydraulic drive unit 40 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 plunger drive unit 30. The supply of these hydraulic oils to the plunger drive unit 30 drives the plunger drive unit 30. The hydraulic drive unit 40 has, for example, accumulators 41 and 42 (pressure accumulation means) and a switching valve 43.

[0022] The accumulators 41 and 42 accumulate the pressure of compressed gas (hereinafter referred to as "pressurized gas") and supply hydraulic oil to the head-side hydraulic chamber 34a of the plunger drive portion 30 using the accumulated pressure.

[0023] The accumulator 41 supplies hydraulic oil to the head-side hydraulic chamber 34a during the injection process. 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.

[0024] The hydraulic oil chamber 41b of the accumulator 41 is connected to the head-side hydraulic chamber 34a. The pressure of the pressurized gas stored in the gas chamber 41c causes the airtight member 41d to move toward the hydraulic oil chamber 41b. As the airtight member 41d moves, hydraulic oil is supplied from the hydraulic oil chamber 41b to the head-side hydraulic chamber 34a.

[0025] The accumulator 42 supplies hydraulic oil to the head-side hydraulic chamber 34a during the pressure increase 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.

[0026] The hydraulic oil chamber 42b of the accumulator 42 is connected to the head-side hydraulic chamber 34a. The pressure of the pressurized gas stored in the gas chamber 42c causes the airtight member 42d to move toward the hydraulic oil chamber 42b. As the airtight member 42d moves, hydraulic oil is supplied from the hydraulic oil chamber 42b to the head-side hydraulic chamber 34a.

[0027] The switching valve 43 is a member that switches between accumulators that supply hydraulic oil to the 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 head-side hydraulic chamber 34a, and a state in which hydraulic oil for boosting is supplied from the accumulator 42 to the head-side hydraulic chamber 34a. The switching valve 43 may be any valve as long as it can switch between these two states.

[0028] (position sensor) The position sensor 48 is a sensor that detects the position of the movable part MP relative to the fixed parts (e.g., the injection sleeve 21 and the cylinder 31) of the injection device 20. There are no particular restrictions on which part of the movable part MP's position is detected. For example, the position sensor 48 is provided on the cylinder 31 and detects the position of the piston rod 32. The position sensor 48 outputs an electrical signal that represents the position of the movable part MP. An example of the position sensor 48 is an optical or magnetic linear scale.

[0029] (Pressure sensor) The pressure sensors 51 and 52 detect the differential pressure acting on the piston head 34. For example, the pressure sensor 51 detects the pressure of the hydraulic oil in the rod-side hydraulic chamber 32a, and the pressure sensor 52 detects the pressure of the hydraulic oil in the head-side hydraulic chamber 34a. The differential pressure is detected as the difference between the pressure detection result by the pressure sensor 52 and the pressure detection result by the pressure sensor 51. The pressure sensor 51 outputs an electric signal representing the pressure of the hydraulic oil in the rod-side hydraulic chamber 32a. The pressure sensor 52 outputs an electric signal representing the pressure of the hydraulic oil in the head-side hydraulic chamber 34a. Examples of pressure sensors include a piezo-resistance pressure sensor and a strain gauge pressure sensor.

[0030] (Control device) The control device 100 controls the injection speed of the molten metal by the injection device 20 based on the detection results of the position sensor 48 and the pressure sensors 51, 52. For example, as shown in FIG. 2, the control device 100 has, as functional components (hereinafter referred to as "functional blocks"), a line memory unit 111 and an injection control unit 112. The line memory unit 111 has a die line and a machine line. The line memory unit 111 stores the die line and the machine line, so that the casting apparatus 1 is equipped with the die line and the machine line.

[0031] The die line indicates the correlation between the injection speed (the speed at which the molten metal is supplied into the cavity 13 via the runner 14) and the injection force required to supply the molten metal into the cavity 13. The die line is a line determined by the mold 10, and indicates, for example, the relationship between the square of the injection speed and the injection force. The line storage unit 111 may store, as the die line, a function that indicates the relationship between the square of the injection speed and the injection force, or may store, as the die line, discrete point cloud data that indicates the relationship between the square of the injection speed and the injection force.

[0032] The machine line indicates the correlation between the injection speed and the injection force that can be generated by the injection unit 20. The machine line is a line determined by the injection unit 20, and represents, for example, the relationship between the square of the injection speed and the injection force. The line storage unit 111 may store, as the machine line, a function that represents the relationship between the square of the injection speed and the injection force, or may store, as the machine line, discrete point cloud data that represents the relationship between the square of the injection speed and the injection force.

[0033] In the die line and machine line, the injection speed may be the volume of molten metal supplied per unit time, the weight of molten metal supplied per unit time, or the forward displacement speed of the movable part MP. The injection force may be the force acting forward from the piston rod 32 on the plunger 22, or the pressure of the molten metal in the injection sleeve 21.

[0034] FIG. 3 is a graph illustrating the die line and the machine line. The horizontal axis represents the square of the injection speed, and the vertical axis represents the injection force. As described above, the die line L1 shows the correlation between the square of the injection speed and the injection force required to supply the molten metal into the cavity 13. As the injection speed increases, the resistance of the flow path into the cavity 13 increases, so the die line L1 is an upward-sloping graph. The machine line L2 shows the correlation between the square of the injection speed and the injection force that the injection device 20 can generate. As the injection speed increases, the flow resistance of the hydraulic oil, etc. increases, so the machine line L2 is a downward-sloping graph.

[0035] Returning to FIG. 2, the injection control unit 112 controls the injection speed of the injection device 20 based on the machine line L2 and die line L1 stored in the line memory unit 111 and the detection results of the position sensor 48 and the pressure sensors 51 and 52. For example, the injection control unit 112 sequentially executes a low-speed injection process, a high-speed injection process, a pressure increase process, and a pressure hold process. The injection control unit 112 starts the low-speed injection process by supplying hydraulic oil from the accumulator 41 to the head-side hydraulic chamber 34a via the switching valve 43. In the low-speed injection process, the injection control unit 112 controls the injection device 20 to advance the plunger 22 while maintaining the injection speed near a predetermined first target injection speed. For example, the injection control unit 112 identifies a first target injection force F1 corresponding to the first target injection speed V1 on the die line L1 stored in the line memory unit 111 (see FIG. 3). The injection control unit 112 calculates the injection force based on the detection results from the pressure sensors 51 and 52, and controls the adjustment valve 35 so that the calculated injection force approaches the first target injection speed V1.

[0036] The injection control unit 112 starts the high-speed injection process when the plunger 22 reaches a predetermined acceleration start position. The acceleration start position is determined, for example, at a position where the injection sleeve 21 is filled with molten metal and the molten metal reaches the vicinity of the entrance of the cavity 13. In the high-speed injection process, the injection control unit 112 controls the injection device 20 to advance the plunger 22 while maintaining the injection speed near a second target injection speed V2 that is higher than the first target injection speed V1. For example, the injection control unit 112 specifies a second target injection force F2 corresponding to the second target injection speed V2 on the die line L1 stored in the line storage unit 111 (see FIG. 3). The injection control unit 112 calculates the injection force based on the detection results of the pressure sensors 51 and 52 and controls the adjustment valve 35 to bring the calculated injection force closer to the second target injection speed V2.

[0037] The injection control unit 112 starts the pressure-increasing process when the plunger 22 reaches a predetermined pressure-increasing start position. The pressure-increasing start position is set to a position where the molten metal fills the cavity 13. During the pressure-increasing process, the injection control unit 112 controls the injection device 20 to increase the injection force acting on the plunger 22 from the piston rod 32. For example, the injection control unit 112 switches the switching valve 43 from a state in which hydraulic oil is supplied from the accumulator 41 to the head-side hydraulic chamber 34a to a state in which hydraulic oil is supplied from the accumulator 42 to the head-side hydraulic chamber 34a. The injection control unit 112 calculates the injection force based on the detection results of the pressure sensors 51 and 52, and controls the adjustment valve 35 to bring the calculated injection force closer to a predetermined post-pressure-increasing target injection force. The post-pressure-increasing target injection force is set to a value higher than the second target injection force, for example.

[0038] The injection control unit 112 starts a pressure dwelling process when the injection force substantially reaches the target injection force after pressure boosting. In the pressure dwelling process, the injection control unit 112 controls the adjustment valve 35 to maintain the injection force close to the target injection force after pressure boosting for a predetermined pressure dwelling period. After the pressure dwelling process, the molten metal in the cavity 13 hardens, forming a casting in the cavity 13. The movable mold 12 is moved away from the fixed mold 11 to open the mold 10, and the casting is removed from the mold 10.

[0039] In the above-described injection unit 20, it is not possible to obtain an injection speed that exceeds the injection speed corresponding to the intersection of the die line L1 and the machine line L2. Hereinafter, the injection speed corresponding to the intersection of the die line L1 and the machine line L2 will be referred to as the "maximum injection speed." Since it is not possible to obtain an injection speed that exceeds the maximum injection speed in the injection unit 20, the injection speed cannot reach the second target injection speed unless the second target injection speed in the high-speed injection process is equal to or lower than the maximum injection speed.

[0040] In the high-speed injection process, the injection force corresponding to the intersection of the die line L1 and the machine line L2 is set as the second target injection force, and the adjustment valve 35 is controlled to approach the second target injection force, thereby enabling the injection speed to reach the maximum injection speed. However, the injection force corresponding to the injection speed on the die line L1 does not include the force required for acceleration and deceleration. Therefore, even if the injection force reaches the second target injection force, the injection speed does not instantly reach the maximum injection speed. The injection speed gradually approaches the maximum injection speed with an acceleration corresponding to the given injection force and the mass of the movable part MP. In the high-speed injection process, it is necessary to quickly fill the cavity 13 with the molten metal. As described above, even if the injection force reaches the second target injection force, it takes time for the injection speed to reach the maximum injection speed, so the molten metal may not necessarily be filled into the cavity 13 within the desired time.

[0041] Therefore, the injection control unit 112 is configured to generate a margin die line by shifting the die line L1 by a predetermined correction amount in a direction to increase the injection force, identify the injection speed corresponding to the intersection of the margin die line and the machine line L2 as a second target injection speed, accelerate the injection speed to the second target injection speed, and maintain the injection speed in the vicinity of the second target injection speed.

[0042] The predetermined correction amount may be equal to or greater than the product of the mass of the movable part MP and the predetermined acceleration. For example, the predetermined correction amount may be the product of the mass of the movable part MP and the predetermined acceleration, or may be a value obtained by adding a predetermined margin to this product. The predetermined acceleration is determined in advance in consideration of the mechanical durability of the injection device 20, etc. In the high-speed injection process, the injection control unit 112 may accelerate the injection speed to the second target injection speed at a predetermined acceleration corresponding to the predetermined correction amount.

[0043] 3, the control executed by the injection control unit 112 in the low-speed injection process and the high-speed injection process will be exemplified. The injection control unit 112 generates a margin die line L11 by shifting the die line L1 by a predetermined correction amount in the direction of increasing the injection force. The injection control unit 112 specifies the injection speed corresponding to the intersection CP2 between the margin die line L11 and the machine line L2 as the second target injection speed V2.

[0044] In the low-speed injection process, the injection control unit 112 controls the injection unit 20 to maintain the injection speed near the first target injection speed V1. For example, the injection control unit 112 identifies a first target injection force F1 corresponding to the first target injection speed V1 on the die line L1, and controls the adjustment valve 35 to bring the injection force closer to the first target injection force F1. When the plunger 22 reaches the acceleration start position, the injection control unit 112 controls the injection unit 20 to bring the combination of injection speed and injection force closer to the intersection point CP2 along the margin die line L11 (see transition line TL1). For example, the injection control unit 112 calculates the injection speed based on the detection result of the position sensor 48, calculates the target injection force corresponding to the injection speed on the margin die line L11, and repeatedly controls the adjustment valve 35 to bring the injection force closer to the target injection force. As a result, an injection force obtained by adding a predetermined correction amount to the injection force at the die line L1 is continuously output, and the movable part MP is accelerated to the second target injection speed V2 at a predetermined acceleration corresponding to the predetermined correction amount.

[0045] When the combination of injection speed and injection force reaches intersection point CP2, the injection control unit 112 controls the adjusting valve 35 to reduce the injection force corresponding to the margin die line L11 to a second target injection force F2 corresponding to the second target injection speed V2 at the die line L1 (see transition line TL2). This cancels the addition of the predetermined correction amount to the die line L1, so that acceleration of the movable part MP stops and the injection speed is maintained near the second target injection speed V2 corresponding to intersection point CP2. When the plunger 22 reaches a predetermined deceleration start position, the injection control unit 112 may control the adjusting valve 35 to reduce the injection force from the second target injection force F2 to the first target injection force F1. This reduces the injection speed from the second target injection speed V2 to the first target injection speed V1 (see transition line TL3).

[0046] FIG. 4 is a graph showing the transition of the injection speed during the low-speed injection process and the high-speed injection process. The horizontal axis represents elapsed time, and the vertical axis represents the injection speed. Time t1 is the time when the plunger 22 reaches the acceleration start position, and time t2 is the time when the plunger 22 reaches the deceleration start position. In FIG. 4, the transition line TL11, represented by a two-dot chain line, represents the transition of the injection speed when the adjustment valve 35 is controlled so as to bring the injection force closer to the target injection force corresponding to the maximum injection speed V3 at the die line L1. As shown by the transition line TL11, the injection speed eventually reaches the maximum injection speed V3, but it takes a long time to reach that speed.

[0047] In Figure 4, the solid line TL12 represents the transition of the injection speed when the injection force is controlled along the margin die line L11, as described above. Because the injection force obtained by adding a predetermined correction amount to the injection force at the die line L1 is continuously output, the movable part MP is rapidly accelerated from the first target injection speed V1 to reach the second target injection speed V2. Thereafter, the injection force corresponding to the margin die line L11 is reduced to the second target injection force corresponding to the die line L1, thereby maintaining the injection speed near the second target injection speed V2. When the plunger 22 reaches the deceleration start position, the second target injection force F2 is reduced to the first target injection force F1, thereby decelerating the injection speed from the second target injection speed V2 to the first target injection speed V1.

[0048] According to the transition line TL12, the injection speed does not reach the maximum injection speed, but the time integral of the injection speed from time t1 to time t2 is clearly larger than the time integral of the injection speed according to the transition line TL11. Therefore, according to the transition line TL12, it is possible to fill the molten metal into the cavity 13 more quickly than with the transition line TL11.

[0049] When the movable part MP is displaced forward, the gas chamber 41c in the accumulator 41 becomes larger, and the compression energy of the gas accumulated in the gas chamber 41c decreases. When the compression energy decreases, the injection force that the injection device 20 can generate according to the injection speed decreases. In response to this, the injection control part 112 may further correct the machine line L2 according to the displacement of the movable part MP. For example, as shown in FIG. 5, the injection control part 112 may shift the machine line L2 in a direction that reduces the injection force as the amount of forward displacement of the movable part MP increases.

[0050] Shifting the machine line L2 in a direction to reduce the injection force as the forward displacement of the movable part MP increases includes switching the machine line L2 to a predetermined corrected machine line L2 as the displacement of the movable part MP reaches a predetermined threshold. For example, the injection control unit 112 may switch the machine line L2 to the corrected machine line L2 as the displacement of the movable part MP reaches a displacement amount corresponding to the acceleration start position (the position of the plunger 22 reaches the acceleration start position).

[0051] The injection control unit 112 may specify the injection speed corresponding to the intersection point CP21 between the margin die line L11 and the corrected machine line L2 as the second target injection speed V21, instead of the intersection point CP2 (see FIG. 3). The injection control unit 112 controls the injection device 20 so that the combination of the injection speed and the injection force approaches the intersection point CP21 along the margin die line L11 (see transition line TL21). When the combination of the injection speed and the injection force reaches the intersection point CP21, the injection control unit 112 controls the adjustment valve 35 so as to reduce the injection force corresponding to the margin die line L11 to a second target injection force F21 corresponding to the second target injection speed V21 on the die line L1 (see transition line TL22). When the plunger 22 reaches a predetermined deceleration start position, the injection control unit 112 may control the adjustment valve 35 so as to reduce the injection force from the second target injection force F21 to the first target injection force F1. As a result, the injection speed is decelerated from the second target injection speed V21 to the first target injection speed V1 (see the transition line TL23).

[0052] As illustrated above, identifying the injection speed corresponding to the intersection of the margin die line L11 and the machine line L2 as the second target injection speed V2 includes identifying the injection speed corresponding to the intersection of the margin die line L11 and the corrected machine line L2 as the second target injection speed V21.

[0053] Fig. 6 is a block diagram illustrating an example of a hardware configuration of the control device 100. As shown in Fig. 6, the control device 100 includes a circuit 190. The circuit 190 includes a processor 191, a memory 192, a storage 193, and an input / output port 194.

[0054] The storage 193 includes, for example, one or more nonvolatile storage media. The nonvolatile storage medium includes one or more storage devices. Examples of the one or more storage devices include a hard disk drive, a solid state drive, and a flash memory. The nonvolatile storage medium may include a portable storage medium such as an optical disk. The storage 193 stores a program that causes the control device 100 to execute the following operations: generate a margin die line by shifting the die line by a predetermined correction amount in a direction to increase the injection force; identify an injection speed corresponding to the intersection of the margin die line and the machine line as a second target injection speed; accelerate the injection speed to the second target injection speed; and maintain the injection speed near the second target injection speed.

[0055] The memory 192 includes one or more volatile storage media. The volatile storage media includes one or more memory devices. An example of the one or more memory devices is a random access memory. The memory 192 temporarily stores a program loaded from the storage 193. The processor 191 includes one or more arithmetic devices. An example of the arithmetic device is a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The processor 191 configures the above-mentioned functional blocks in the control device 100 by executing the program loaded in the memory 192. The processor 191 may temporarily store the calculation results in the memory 192. The input / output port 194 includes one or more communication ports. The input / output port 194 inputs and outputs electrical signals to and from the position sensor 48, the pressure sensors 51 and 52, the adjustment valve 35, and the switching valve 43 in response to a request from the processor 191.

[0056] The configuration of the control device 100 shown above is an example and can be changed. All of the above-described functional blocks do not have to be configured by executing a program in the storage 193. For example, at least some of the functional blocks may be configured by a circuit specialized for that function, such as an ASIC (Application Specific Integrated Circuit).

[0057] [Casting method] As an example of a casting method, a casting procedure executed by the control device 100 will be illustrated. As shown in Fig. 7, the control device 100 first executes steps S01 and S02. In step S01, the injection control unit 112 causes the injection device 20 to apply a first target injection force F1 to the plunger 22 in the forward direction. This starts the low-speed injection process, and the plunger 22 moves forward at a first target injection speed V1. In step S02, the injection control unit 112 waits for the plunger 22 to reach an acceleration start position.

[0058] Next, the control device 100 executes steps S03, S04, and S05. In step S03, the injection control unit 112 generates a margin die line L11 by shifting the die line L1 by a predetermined correction amount in the direction of increasing the injection force. In step S04, the injection control unit 112 corrects the machine line L2 in the direction of decreasing the injection force. In step S05, the injection control unit 112 identifies the injection speed corresponding to the intersection CP21 between the margin die line L11 and the corrected machine line L2 as a second target injection speed V21.

[0059] Next, the control device 100 executes steps S06, S07, and S08. In step S06, the injection control unit 112 starts controlling the injection unit 20 so that the combination of injection speed and injection force approaches the intersection point CP21 along the margin die line L11. In step S07, the injection control unit 112 waits for the combination of injection speed and injection force to reach the intersection point CP21 (the injection speed reaches the second target injection speed V21). In step S08, the injection control unit 112 controls the adjustment valve 35 to reduce the injection force corresponding to the margin die line L11 to the second target injection force F2 corresponding to the die line L1. This stops the acceleration of the plunger 22, and the injection speed is maintained near the second target injection speed V21.

[0060] Next, the control device 100 executes steps S09 and S11. In step S09, the injection control unit 112 waits for the plunger 22 to reach a predetermined deceleration start position. In step S11, the injection control unit 112 controls the adjustment valve 35 to reduce the injection force from the second target injection force F2 to the first target injection force F1. As a result, the injection speed decreases from the second target injection speed V21 to the first target injection speed V1.

[0061] Next, the control device 100 executes steps S12, S13, and S14. In step S12, the injection control unit 112 waits for the plunger 22 to reach the pressure increase start position. In step S13, the injection control unit 112 controls the injection device 20 so as to increase the injection force acting on the plunger 22 from the piston rod 32 to the target injection force after pressure increase. In step S14, the injection control unit 112 controls the adjustment valve 35 so as to maintain the injection force near the target injection force after pressure increase over a predetermined pressure holding period.

[0062] After the pressure holding step, the molten metal in the cavity 13 hardens, forming a casting in the cavity 13. The movable mold 12 is moved away from the fixed mold 11 to open the mold 10, and the casting is removed from the mold 10. This completes the casting molding procedure. The above procedure is an example and can be modified. For example, the generation of the margin die line L11, the correction of the machine line L2, and the calculation of the second target injection speed V21 in steps S03, S04, and S05 may be performed prior to step S01.

[0063] 〔summary〕 The above-described exemplary embodiment includes the following configurations. (1) A casting molding apparatus 1 comprising a mold 10, a cavity 13 formed by the mold 10, an injection means 20 driven by hydraulic oil to inject molten metal into the cavity 13, a control means 100 for controlling the injection speed of the injection means 20, a die line L1 showing the correlation between the injection speed and the injection force required to supply the molten metal into the cavity 13, and a machine line L2 showing the correlation between the injection speed and the injection force that the injection means 20 can generate, wherein the control means 100 is configured to: generate a margin die line L11 by shifting the die line L1 by a predetermined correction amount in a direction that increases the injection force; identify the injection speed corresponding to the intersection of the margin die line L11 and the machine line L2 as a target injection speed; accelerate the injection speed to the target injection speed and maintain the injection speed in the vicinity of the target injection speed. The injection speed corresponding to the intersection of the die line L1 and the machine line L2 (hereinafter referred to as the "reference intersection") is the maximum injection speed obtainable by the injection means 20. The intersection of the die line L1 and the machine line L2 indicates that injection at the maximum injection speed is possible by generating the injection force corresponding to the intersection in the injection means 20. However, in actual casting, generating the injection force corresponding to the intersection in the injection means 20 does not immediately obtain the maximum injection speed; rather, due to the influence of the inertia of the moving parts of the injection means 20, there is a delay before reaching the maximum injection speed. As described above, the target injection speed corresponding to the intersection of the spare die line L11, which is obtained by shifting the die line L1, and the machine line L2 (hereinafter referred to as the "shift intersection") is lower than the maximum injection speed. On the other hand, because the injection force corresponding to the shift intersection is higher than the injection force corresponding to the reference intersection, acceleration to the target injection speed is possible with a higher injection force than acceleration to the maximum injection speed. Acceleration with a high injection force allows the target injection speed to be reached with high responsiveness, so the molten metal can be filled into the cavity 13 in a shorter time than waiting to reach the maximum injection speed with the injection force corresponding to the reference intersection. Therefore, this device is effective in further improving the quality of die-cast products.

[0064] (2) The casting molding apparatus 1 described in (1) has an injection means 20 having a movable part that moves as the molten metal is supplied, the predetermined correction amount is equal to or greater than the product of the mass of the movable part and a predetermined acceleration, and the control means 100 accelerates the injection speed to the target injection speed at the predetermined acceleration. By adjusting the combination of the acceleration and the target injection speed, the filling time of the molten metal can be further shortened.

[0065] (3) The casting molding apparatus 1 according to (2), wherein the control means 100 accelerates the injection speed to the target injection speed and then reduces the injection force to a value corresponding to the die line L1. By stabilizing the injection speed after reaching the target injection speed, further quality improvement can be achieved.

[0066] (4) A casting molding apparatus 1 described in (2) or (3), in which the hydraulic oil is supplied to the injection means 20 by a pressure accumulator means, and the control means 100 further corrects the machine line L2 according to the displacement of the movable part, and identifies the injection speed corresponding to the intersection of the margin die line L11 and the corrected machine line L2 as the target injection speed. It is possible to suppress a decrease in responsiveness up to the target injection speed due to a change in pressure in the pressure accumulating means in response to the displacement of the movable part.

[0067] (5) The casting molding device 1 according to (4), wherein the control means 100 shifts the machine line L2 in a direction to reduce the injection force as the displacement of the movable part in the direction of injecting the molten metal increases. It is possible to suppress a decrease in response up to the target injection speed due to a decrease in pressure in the pressure accumulating means. Although the embodiments have been described above, the present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0068] 1...casting molding device, 10...mold, 13...cavity, 20...injection means, 41, 42...accumulation means, 100...control means, L1...die line, L2...machine line, L11...slack die line.

Claims

1. The mold and a cavity formed by the mold; an injection means driven by hydraulic oil to inject molten metal into the cavity; a control means for controlling the injection speed of the injection means; a die line showing the correlation between the injection speed and the injection force required to supply the molten metal into the cavity; a machine line showing the correlation between the injection speed and the injection force that the injection means can generate; Equipped with The control means generating an extra die line by shifting the die line by a predetermined correction amount in a direction to increase the injection force; Identifying the injection speed corresponding to the intersection of the margin die line and the machine line as a target injection speed; accelerating the injection speed to the target injection speed and maintaining the injection speed near the target injection speed; The casting molding device is configured to perform the steps of:

2. the injection means has a movable part that moves in accordance with the supply of the molten metal, the predetermined correction amount is equal to or greater than the product of the mass of the movable part and a predetermined acceleration, the control means accelerates the injection speed to the target injection speed at the predetermined acceleration. The casting molding apparatus of claim 1.

3. the control means accelerates the injection speed to the target injection speed and then reduces the injection force to a value corresponding to the die line; 3. The casting molding apparatus according to claim 2.

4. The hydraulic oil is supplied to the injection means by a pressure accumulator means, The control means further corrects the machine line in accordance with the displacement of the movable part; Identifying the injection speed corresponding to the intersection of the margin die line and the corrected machine line as the target injection speed; 4. The casting molding apparatus according to claim 2 or 3.

5. the control means shifts the machine line in a direction to reduce the injection force in response to an increase in the displacement amount of the movable part in the direction to inject the molten metal.

5. The casting molding apparatus according to claim 4.

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