JP7600665B2 - Die casting machine, control device and program for die casting machine, and casting method - Google Patents

Description

The present invention relates to a die casting machine, a control device and program used to set and control the injection device of the die casting machine, and a casting method.

Casting using a die-casting machine involves an injection filling process in which the plunger of the injection device is advanced to push out the molten metal in the sleeve and fill the cavity, and a pressure boosting process in which the plunger presses against the molten metal that has filled the entire cavity, increasing the molten metal pressure (casting pressure) and applying a specified pressure to the molten metal.
The plunger is driven by an injection cylinder (hydraulic cylinder) connected to a plunger rod.

Patent Document 1 describes a hydraulic circuit including a hydraulic cylinder, an accumulator, and multiple valves. By flowing hydraulic oil from the accumulator into the head side of the injection cylinder, the hydraulic pressure acts as a driving force to move the plunger forward and inject the molten metal. After that, when a valve included in the hydraulic circuit is operated to switch from the injection filling system to the boosting system, a specified pressure is applied to the molten metal via the plunger due to the hydraulic oil flowing from the boosting system into the injection cylinder, so that the space created by the entrapment of gas in the molten metal is collapsed, and the molten metal is replenished in the cavity to make up for the shrinkage caused by the solidification of the molten metal.

The control device of the injection device described in Patent Document 2 aims to manage the time lag from the completion of filling to the start of pressure increase (pressure boosting start), by measuring a filling pressure increase completion time T _C corresponding to the time from when gate resistance occurs in the injection cylinder to when the casting pressure reaches a set pressure, and controls the operation of the injection cylinder based on the measurement result so that the filling pressure increase completion time T _C becomes a target value.
Specifically, the filling time from the time when gate resistance occurs in the injection cylinder to the time when filling is completed and surge pressure occurs in the injection cylinder, the time lag from the time when surge pressure occurs in the injection cylinder to the time when the casting pressure starts to rise, and the pressure rise time from the time when the casting pressure starts to rise to the time when the casting pressure reaches the set pressure are measured. Based on the results of these measurements, the control device corrects the control parameters related to the plunger speed and the valve opening of the hydraulic circuit so that the filling and pressure rise completion time T _C becomes a target value, and the filling time and pressure rise time are corrected accordingly.

In other words, in Patent Document 2, the filling and boosting completion time T _C including the time lag is managed to include the time lag that may be longer than expected in the management, thereby unifying the management.
According to Patent Document 2, when a surge pressure is detected in the injection cylinder or the plunger reaches a predetermined position, thereby establishing a condition for starting boosting, measurement of the filling time is terminated and measurement of the time lag is started, and the boosting operation is started by issuing a command to start boosting to the valve in the hydraulic circuit.

Patent No. 6582834 JP 2007-245231 A

In Patent Document 2, a time lag is permitted between the time when a surge pressure is generated in the injection cylinder due to completion of filling of the cavity and a command to start increasing the pressure is issued by the control device to the valve of the hydraulic circuit and the time when the plunger is pushed by the hydraulic pressure and the casting pressure starts to increase, i.e., a delay in starting the increase in pressure.
Such a time lag inevitably occurs due to the time required for signal transmission, control processing, valve operation, and hydraulic oil movement.
However, in order to start increasing the pressure immediately after filling is completed and to propagate the pressure sufficiently throughout the entire cavity before the molten metal solidifies, and thereby to obtain a quality product, it is desirable to eliminate any delay in starting the pressure increase as much as possible.

In order to eliminate the delay in starting the boost process, the position of the plunger is detected and the boost process is started when the plunger reaches a position that is a time lag prior to the completion of filling. However, since the advance switch position is set based on the plunger speed corresponding to the plunger position, the advance switch position is not necessarily set to an appropriate position depending on the casting conditions. If the advance switch position is set to an unintended position, it is not possible to realize the waveforms of speed and pressure that correspond to the casting conditions.
In view of the above, an object of the present invention is to eliminate the delay between the completion of filling and the start of pressure boosting by setting an appropriate advance switch position, and to realize speed and pressure waveforms corresponding to the casting conditions.

In order to eliminate the delay in starting the boosting process, the inventors of the present invention have tried to set a precedence switching position for switching to the boosting process prior to the completion of filling for various casting conditions.
The control device of the die casting machine detects the position of the plunger using a linear encoder, etc., and controls the injection device based on predetermined casting conditions including the plunger speed and casting pressure. Specifically, the control device controls the speed at which the plunger moves to a predetermined injection speed, and transitions from speed control to pressure control when the valve switches from the injection filling system to the boosting system.
While the plunger is being moved moment by moment, when it is detected that the plunger has reached a preceding switching position, which is a displacement amount calculated from the plunger speed and time lag, which is located back from the position at the time of completion of filling, a switching command is output from the control device to the valve of the hydraulic circuit.
However, since the advance switching position changes with changes in the plunger speed, the inventors of the present invention have found that there is a drawback to the advance switching position set for some casting conditions, as described below.

The injection operation by the plunger is typically performed by keeping the plunger moving speed low until halfway through the injection filling process, and then increasing the plunger moving speed towards the end of the injection filling process, in order to avoid entraining air in the molten metal.
In recent years, the high-speed section has tended to become shorter against the background of the increase in the speed of the injection stroke. Therefore, the high-speed section may be so short that the advance switching position, which is back by a specified time lag based on the plunger speed, is set in the low-speed section of the injection stroke prior to the completion of filling in the high-speed section. In other words, the high-speed section is short relative to the displacement of the plunger corresponding to the delay in the start of boosting. Under such casting conditions, the advance switching position, which is back by a specified time lag based on the plunger speed in the low-speed section, is set in the high-speed section, and when the low-speed section is switched to the high-speed section, the advance switching position is set in the low-speed section. In that case, even if a command to start boosting is issued at the advance switching position prior to the completion of filling, the advance switching position is in the low-speed section that has already been passed, so there is no way to eliminate the delay in starting boosting. In this case, there is no other way than to issue a command to start boosting immediately after switching from the low-speed section to the high-speed section.
Even if the high-speed section is not short, if the time lag is long, the advance switch position that is back by a specified time lag based on the plunger speed may be set in the low-speed section of the injection stroke prior to the completion of filling in the high-speed section, as described above. In this case, too, the advance switch position that has passed may be set unintentionally at the time of switching from the low-speed section to the high-speed section.

Furthermore, in a casting condition in which the plunger is decelerated after the low-speed and high-speed sections of the injection stroke, the advance switch position, which is set based on the plunger speed prior to the completion of filling, may be set to a position that is further back than the amount of displacement required to eliminate the delay in starting boosting. In that case, after reaching the advance switch position, there is a time lag and the hydraulic circuit switches to the boosting system before filling is complete. This causes a sudden increase in plunger speed because filling is not yet complete, resulting in a decrease in casting pressure as the hydraulic pressure for boosting is consumed for the speed increase.

In any of the casting conditions exemplified above, the advance switching position is set at an unintended position, so that it is not possible to realize the speed and pressure waveforms corresponding to the casting conditions, making it difficult to obtain a quality product.
Alternatively, it may be possible to output a command to start increasing the pressure when a pressure sensor or the like detects that the molten metal has reached the cavity. However, this would lead to a delay in detecting the arrival of the molten metal, and so it would be difficult to fully eliminate the delay in starting to increase the pressure after filling is complete.

The present invention has been made based on the above-mentioned new findings.
The present invention is a control device used to set up and control an injection device of a die casting machine.
The speed of a plunger provided in the injection device changes at a plurality of speed switching positions during an injection stroke for injecting molten metal into a cavity.
The control device is capable of setting a preceding switching position that is obtained by going back from the boost switching position by a delayed displacement amount as the displacement amount of the plunger corresponding to the delay time, based on an injection pattern that can identify a plurality of speed switching positions and speeds that respectively correspond to the plurality of speed switching positions, a boost switching position that corresponds to a position at which switching is made from injection filling, which involves injecting and filling the molten metal into the cavity, to boosting, which increases the pressure of the molten metal in the cavity, and a delay time required for switching from completion of filling to start of boosting.
When the distance from the pressure increase switching position to the speed switching position immediately preceding the pressure increase switching position is shorter than the delay displacement amount, the control device sets a preceding switching position that is located back from the pressure increase switching position by more than one speed switching position, and outputs a command to start pressure increase at the preceding switching position in the injection stroke.

In the control device for a die casting machine of the present invention, the injection stroke includes multiple sections divided by multiple speed switching positions, and the injection stroke includes an acceleration section in which the moving plunger is accelerated from a first speed, and a high-speed section in which the plunger is moved at a second speed after passing through the acceleration section, and the boost switch position is located in the high-speed section, and it is preferable that the length from the boost switch position to the speed switch position corresponding to the start point of the high-speed section is shorter than the delay displacement amount.

In the control device for a die casting machine of the present invention, the injection stroke includes multiple sections divided by multiple speed switching positions, and the injection stroke includes the following sections: an acceleration section in which the moving plunger is accelerated from a first speed, a high-speed section in which the plunger is moved at a second speed after passing through the acceleration section, a deceleration section following the high-speed section, and a low-speed section before completion of filling in which the plunger is moved at a third speed after passing through the deceleration section; the boost switch position is located in the low-speed section before completion of filling, and it is preferable that the length from the boost switch position to the speed switch position corresponding to the start of the low-speed section before completion of filling is shorter than the delay displacement amount.

The control device for a die casting machine of the present invention preferably includes a memory unit for storing data, and when the control device acquires the advance switching position for each of the multiple injection patterns used in the injection device, the control device preferably associates the advance switching position with the injection pattern and stores it as data in the memory unit.

The control device for a die casting machine of the present invention preferably includes a leading switch position calculation unit that calculates a leading switch position, and the leading switch position calculation unit preferably includes a retroactive time calculation unit that calculates a retroactive time from the boost switch position to each of a plurality of speed switch positions for each speed switch position, a previous position determination unit that determines a previous position, which is the speed switch position immediately before the leading switch position, from the retroactive time and the delay time, and a leading switch position calculation unit that converts the time from the previous position to the leading switch position into the leading switch position.

The die casting machine of the present invention comprises the above-mentioned die casting control device, an injection device, and a hydraulic circuit used to drive the injection device.

The present invention also relates to a program for use in setting and controlling an injection device of a die casting machine. The injection device includes a plunger whose speed changes at a plurality of speed switching positions during an injection stroke for injecting molten metal into a cavity.
The program of the present invention can set a preceding switch position that is obtained by going back from the boost switch position by a delayed displacement amount as the displacement amount of the plunger corresponding to the delay time, based on a plurality of speed switch positions and an injection pattern that can identify speeds corresponding to each of the plurality of speed switch positions, a boost switch position that corresponds to a position at which to switch from injection filling, which involves injecting and filling the molten metal into the cavity, to boost pressure, which increases the pressure of the molten metal in the cavity, and a delay time required for switching from completion of filling to start of boost pressure.
Furthermore, when the distance from the pressure increase switching position to the speed switching position immediately preceding the pressure increase switching position is shorter than the delay displacement amount, the program sets a preceding switching position that is located back from the pressure increase switching position by more than one speed switching position, and outputs a command to start pressure increase at the preceding switching position in the injection stroke.

The present invention is a casting method for injecting and filling a cavity with molten metal while changing the speed of a plunger provided in an injection device of a die casting machine at multiple speed switching positions in the injection stroke of the plunger, and includes the steps of: setting a leading switching position that goes back beyond one or more speed switching positions from the boost switching position and a delayed displacement amount as the displacement amount of the plunger corresponding to the delay time based on an injection pattern that can identify multiple speed switching positions and the speeds corresponding to the multiple speed switching positions, a boost switching position that corresponds to a position where the injection filling that injects and fills the cavity with molten metal is switched to boosting that increases the pressure of the molten metal in the cavity, and a delay time required for switching from the completion of filling to the start of boosting; and outputting a command to start boosting at the leading switching position in the injection stroke.

According to the present invention, based on the boost pressure switching position, delay time, and injection pattern, a leading switch position that goes beyond one or more speed switching positions from the boost pressure switching position and traces the delay displacement amount of the plunger corresponding to the delay time can be calculated and set in the control device. By outputting a boost pressure switching command at the set leading switch position, it is possible to eliminate delays or advances in the start of boost pressure relative to the completion of filling, and to produce a quality product by realizing a speed/pressure waveform that corresponds to the casting conditions.

1 is a diagram showing a schematic diagram of an injection device of a die casting machine according to an embodiment of the present invention, a control device used to set and control the injection device, and a mold. FIG. 1 is a graph showing an example of plunger speed and casting pressure during casting. 3 is a graph showing injection patterns corresponding to casting conditions similar to those of FIG. 2 . FIG. 2 is a schematic diagram of an example of a hydraulic circuit for driving the injection device shown in FIG. 1 . 2A is a block diagram showing the general configuration of the control device shown in Fig. 1. FIG. 2B is a schematic diagram showing the internal configuration of a program setting module. FIG. 2C is a diagram showing an example of an injection pattern stored in a storage unit. 4 is a diagram for explaining a procedure for calculating a preceding switching position that matches the injection pattern shown in FIG. 3 . 13 is a graph showing an example of another ejection pattern. 8 is a graph showing plunger speed and casting pressure corresponding to the injection pattern shown in FIG. 8 is a diagram showing an example of calculation of a preceding switching position that matches the injection pattern shown in FIG. 7 .

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
The die casting machine 1 shown in FIG. 1 includes an injection device 10 that injects molten metal such as an aluminum alloy into a cavity 4 formed by a fixed die 2 and a movable die 3, a clamping device 5 that applies a clamping force to the fixed die 2 and the movable die 3, a hydraulic circuit 20 (FIG. 4) that drives the injection device 10, and a control device 30 that is used to set and control the injection device 10.
The mold clamping device 5 includes a fixed platen 51, and a movable platen and tie bars (not shown).

(Injection unit)
The injection device 10 is provided on a fixed platen 51 and includes a sleeve 11 into the inside of which molten metal is supplied, and a plunger 12 that is driven to be able to advance and retreat relative to the sleeve 11 .
The plunger 12 includes a tip 121 that pushes out the molten metal 13 toward the cavity 4, and a rod 122 that supports the tip 121. The rod 122 is coupled via a coupling 123 to a piston rod 210R provided in an injection cylinder 21 that constitutes the hydraulic circuit 20.

The plunger 12 injects the molten metal 13 by moving forward toward the cavity 4 while being driven and controlled according to predetermined casting conditions, using the pressure determined by the pressure on the piston head 210H side and the pressure on the piston rod 210R side of the injection cylinder 21 as a driving force. The plunger 12 moves forward from the origin position until it stops as the molten metal is completely filled into the entire cavity 4. The range of movement of the plunger 12 is called the injection stroke.

The molten metal injected by the plunger 12 is filled into the cavity 4 from the gate 7 through the runner 6. Upon completion of filling the entire cavity 4 with the molten metal, the hydraulic source connected to the injection cylinder 21 is switched, and the process transitions from the injection filling process, in which injection and filling are performed, to a pressure increase process, in which the plunger 12 increases the pressure of the molten metal in the cavity 4.
At this time, the drive control of the plunger 12 is switched from the control based on the speed of the plunger 12 to the control based on a value correlated with the pressure (casting pressure) of the molten metal in the cavity 4, typically the pressure on the piston head 210H side and the pressure on the piston rod 210R side of the injection cylinder 21. For example, a value calculated by subtracting the product of the pressure on the piston rod 210R side and the piston rod side area 210RS from the product of the pressure on the piston head 210H side and the piston head side area 210HS by the tip area 121S can be used for the drive control of the plunger 12.

(Casting Process)
The die casting machine 1 is capable of repeatedly performing a casting cycle consisting of processes such as mold clamping, pouring molten metal, injection filling, pressure increase, cooling, mold opening, product removal, and supply of mold release agent to the mold according to the casting conditions.
2 shows an example of the speed of the plunger 12 and the casting pressure in a casting process using the die casting machine 1. A position on the injection stroke corresponding to the time of switching from the injection filling step A1 to the pressure boosting step A2 is referred to as a pressure boosting switching position _Pvp .
In Fig. 2, the speed of the plunger 12 is indicated by a dashed line, and the casting pressure is indicated by a solid line. The casting pressure corresponds to a pressure calculated using the head side pressure (thick dashed line) and the rod side pressure (dash-dotted line) of the injection cylinder 21. In the pressure range in Fig. 2, the casting pressure is greater than the head side pressure. The same is true in Fig. 8.

2, the casting pressure indicated by the dotted line and the head side pressure indicated by the thin dashed line show Comparative Example 1 with respect to this embodiment. The time when the casting pressure in Comparative Example 1 starts to increase (pressure boost start time _ts ) is delayed by a delay time _Td from the filling completion time _tf when the molten metal is filled throughout the cavity 4. In contrast to Comparative Example 1, this embodiment realizes elimination of the delay from filling completion time _tf to pressure boost start time _ts .
The delay time _Td corresponds to the time required for, for example, signal transmission, control processing, operation of the valves of the hydraulic circuit 20, movement of hydraulic oil, and the like.

In the injection filling step A1, control is performed to make the movement of the plunger 12 follow an injection pattern related to the position and speed of the plunger 12. In Figures 2 and 3, the injection pattern is shown by a solid line connecting the plots of black circles.
To detect the position and speed of the plunger 12, a sensor 8 (FIG. 1), such as a linear encoder mounted on the piston rod 210R, can be used.

In the pressure-increasing step A2, under control based on the pressure on the head side and the pressure on the rod side of the injection cylinder 21, the plunger 12 presses the molten metal, replenishing the cavity 4 with the amount of molten metal that shrinks due to solidification, while applying a specified casting pressure to the molten metal. In the pressure-increasing step A2, the casting pressure is increased to a specified value, and then the molten metal in the cavity 4 is solidified while being maintained at the specified value (pressure holding) until the end of the pressure-increasing step A2. Thereafter, the dies 2 and 3 are opened to remove the product from the cavity 4, and the plunger 12 is retracted to the origin position, and the process moves to the next casting cycle.

(Injection Pattern)
Fig. 3 shows an injection pattern based on one casting condition. The horizontal axis of Fig. 3 indicates the position of the plunger 12 on the injection stroke, and the vertical axis indicates the moving speed of the plunger 12. The speed of the plunger 12 is switched at a plurality of speed switching positions _P1 , _P2 , and _P3 in the injection stroke. According to the injection pattern, it is possible to specify the speed switching positions _P1 , _P2 , and _P3 and the speeds of the plunger 12 corresponding to the speed switching positions _P1 , _P2 , and _P3 , respectively. The advance switching position _Pp is set based on the boost switching position _Pvp , the delay time _Td , and the injection pattern, as described later.
The injection stroke of the plunger 12 includes a plurality of sections S1, _S2 , S3, and S4 that are divided by speed switching positions _P1 , P2, and _P3 .

From the start to the middle of the injection filling process A1, in order to prevent air from being entrained in the molten metal, the plunger 12 is moved at a relatively slow speed, but it is desirable to rapidly accelerate the plunger 12 at the speed switching position _P2 to perform injection and complete filling while the molten metal is hot in a short time. The speed switching position _P2 corresponds to the position of the plunger 12 when the molten metal reaches the gate 7, for example.

According to the injection pattern shown in Fig. 3, the forward movement of the plunger 12 is started at the speed switching position _P0, and the plunger 12 is accelerated to the target first speed _V1 at a predetermined acceleration (first section S1), and the speed of the plunger 12 is maintained at the first speed _V1 from the speed switching position _{P1 to} the speed switching position P2 (second section S2). After that, the target speed of the plunger 12 is switched to the second speed _V2 at the speed switching position _P2 , and the plunger 12 is accelerated from the first speed _V1 to the second speed _V2 at a predetermined acceleration (third section S3), and the plunger 12 continues to move at the second speed _V2 (fourth section S4). The fourth section S4 corresponds to the position from the speed switching position _P3 to the end position _P4 of the injection stroke. As for the actual behavior of the plunger 12 in the fourth section S4, as shown in Fig. 2, the plunger 12 decreases in speed and stops when the filling of the molten metal is completed ( _tf ). If the position of the plunger 12 at the time _tf when filling is completed is _Pf , then _Pf < _P4 .

(Hydraulic circuit)
4 shows an example of the configuration of the hydraulic circuit 20. The hydraulic circuit 20 includes an injection cylinder 21 that hydraulically drives the plunger 12 of the injection device 10, a charging accumulator 22, a boosting accumulator 23, a hydraulic pump 24, a flow rate regulating valve 25 that can adjust the flow rate of the hydraulic oil supplied to the injection cylinder 21, on-off valves 261 to 264 that are opened and closed as appropriate, a check valve 27 that prevents backflow of the hydraulic oil to the hydraulic pump 24, and a storage tank 28 that stores the hydraulic oil.

The injection cylinder 21 includes a cylinder body 211, a piston 210, an inflow oil chamber C1 on the piston head 210H side, and a discharge oil chamber C2 on the piston rod 210R side. The inflow oil chamber C1 is switchably connected to the charging accumulator 22 and the boosting accumulator 23 by opening and closing the on-off valves 261 and 262.
The discharge oil chamber C2 is connected to a storage tank 28 via a flow rate control valve 25 whose spool is driven by a servo motor 25A. The flow rate control valve 25 controls the discharge flow rate of the hydraulic oil from the discharge oil chamber C2, thereby controlling the moving speed of the plunger 12.

The charging accumulator 22 and the boosting accumulator 23 are configured to be able to supply an inert gas such as nitrogen gas from a gas supply source (not shown) to the compartment above the pistons 22A and 23A in each cylinder. The charging accumulator 22 supplies hydraulic oil to the inflow oil chamber C1 using the stored pressure. The same is true for the boosting accumulator 23.

When pressure is stored in the charging accumulator 22, the on-off valves 261 and 263 are opened, and the on-off valves 262 and 264 are closed. With this in mind, the hydraulic oil in the storage tank 28 is pumped by the hydraulic pump 24 to the charging accumulator 22 until the pressure of the hydraulic oil in the charging chamber 22B reaches a predetermined value required to sufficiently and rapidly accelerate the plunger 12 to the injection filling step A1 and inject it at high speed. When pressure accumulation in the charging accumulator 22 is completed, the on-off valves 261 and 263 are closed.

When storing pressure in the boost accumulator 23, the on-off valves 262, 263 are opened and the on-off valves 261, 264 are closed. With this, the hydraulic oil in the storage tank 28 is pumped by the hydraulic pump 24 to the boost accumulator 23 until the pressure of the hydraulic oil in the filling chamber 23B reaches a predetermined value required to apply a specified casting pressure to the molten metal in the cavity 4.
When the accumulation of pressure in the pressure-boosting accumulator 23 is completed, the on-off valves 262 and 263 are closed.
The injection charging step A1 is started with pressure stored in the charging accumulator 22 and the boosting accumulator 23. After the injection charging step A1 and the boosting step A2 are completed, hydraulic oil is pumped to the discharge oil chamber C2 by a system (not shown) of the hydraulic circuit 20, and the hydraulic oil in the inlet oil chamber C1 is drained to the tank, thereby retracting the plunger 12.

Various known hydraulic circuits for die casting may be used instead of the hydraulic circuit 20. Hydraulic circuits that can be substituted for the hydraulic circuit 20 are described in, for example, Japanese Patent No. 6,582,834.
The hydraulic circuit 20 does not necessarily need to have two accumulators 22, 23, one for injection filling and one for boosting pressure, but it is sufficient if it has an injection filling system and a boosting pressure system that can be switched to provide the required speed during injection filling and the required pressure during boosting pressure from the injection cylinder 21 to the plunger 12.

(Control device)
The control device 30 includes a control device main body 31, and a monitor 32 and an external storage medium 33 connected to the control device main body 31, as shown in an example of a hardware configuration in FIG.
The control device main body 31 is composed of a computer device or the like, and is equipped with a calculation unit 311 such as a CPU (Central Processing Unit), a memory 312, a storage unit 313 (storage medium) that stores data such as setting values and programs, and an input/output unit 314.

The control device 30 controls at least the plunger 12 of the injection device 10 and the hydraulic circuit 20 that drives the plunger 12 among various devices of the die casting machine 1 according to the casting conditions set according to the product. This control device 30 may form part of a control device that controls the operation of the die casting machine 1 throughout the entire casting process in cooperation with the injection device 10 and the hydraulic circuit 20, as well as the mold clamping device 5, a water heater (not shown), a product removal mechanism, a vacuum suction device, etc.

The control device 30 can set a boost switch position P _vp , a precedence switch position P _p , and a delay time T _d as set values required for control, and store them in the storage unit 313 .
As the pressure boost switching position _Pvp and the delay time _Td , for example, values input by an operator using the input/output unit 314 based on the results of a test or simulation can be set in the control device 30. At that time, as the pressure boost switching position _Pvp , for example, the position of the plunger 12 when the pressure on the piston head 210H side of the injection cylinder 21 reaches a specified pressure can be adopted.
The delay time _Td is a value specific to the die casting machine 1 used. Even die casting machines 1 with the same configuration may have different values of the delay time _Td due to individual differences.
As the advanced switching position _Pp , a value calculated by executing a computer program (hereinafter, simply referred to as the program) installed in the control device 30 can be set in the control device 30.

In addition, the control device 30 issues control commands to the flow control valve 25 and the on-off valves 261 to 264 of the hydraulic circuit 20 based on the installed program, and operates these valves to apply a driving force to the plunger 12 to perform the injection filling process A1 and the pressure boosting process A2.
The program installed in the control device 30 includes at least a calculation/setting module (leading switch position calculation unit) capable of calculating and setting the leading switch position _Pp , and a drive control module that drives and controls the plunger 12 through the operation of the valve of the hydraulic circuit 20. As shown in FIG. 5B, the setting module includes a retroactive time calculation unit 315, a previous position specification unit 316, and a leading switch position calculation unit 317.

The memory unit 313 stores the boost switch position _Pvp , the advance switch position _Pp , and the delay time _Td , all of which are set values, an injection pattern (FIG. 5(c)) relating to the position and speed of the plunger 12, a program used to set the advance switch position _Pp and control the drive of the plunger 12, and data necessary for executing the program.

5(c), the injection pattern is made up of data including at least positions _P1 , _P2 , _P3 where the speed of the plunger 12 is switched, a start position _P0 and an end position _P4 of the injection pattern, and speeds _V0 , _V1 , _V2 , _V3 corresponding to each position. The injection pattern is such that the speed is switched at least at two positions after the start of injection. Hereinafter, positions _P0 to _P4 , including the start position _P0 and end position _P4 of the injection pattern, will be referred to as speed switching positions.
The injection pattern is sufficient as long as it includes information capable of identifying a plurality of speed switching positions of the plunger 12 and the speeds corresponding to the respective speed switching positions. For example, the injection pattern may include the speed switching positions and the elapsed time from the start position of the injection stroke.

The storage unit 313 stores a plurality of injection patterns in an appropriate data format such as table data that can correspond to various casting conditions used in the die casting machine 1. The boost switch position _Pvp and the advance switch position _Pp are set for each injection pattern, and are stored in the storage unit 313 in a state of being linked to a specific injection pattern.

At the start of the injection filling process A1, the control device 30 opens the on-off valves 261, 264 to supply hydraulic oil from the filling accumulator 22 to the inflow oil chamber C1 of the injection cylinder 21, and also gives the flow rate control valve 25 an opening corresponding to the first speed _V1 , which is the target value of the speed of the plunger 12. Thereafter, the control device 30 gives the flow rate control valve 25 an opening corresponding to the second speed _V2 at the speed switching position _P1 , thereby rapidly accelerating the plunger 12 and injecting the molten metal into the cavity 4.
When the control device 30 detects by the sensor 8 or the like that the plunger 12 has reached the set preceding switch position _Pp , it generates a pressure boost start command to start boosting the pressure, thereby closing the on-off valve 261 and opening the on-off valve 262, and switching the hydraulic power source connected to the injection cylinder 21 from the filling accumulator 22 to the pressure boosting accumulator 23.

When the filling state of the molten metal in the cavity 4 approaches completion, the casting pressure draws an upward curve, as shown in Fig. 2. It is desirable to make this upward curve steep enough to prevent the occurrence of casting burrs, and to minimize the time required for pressure increase. By sufficiently propagating the pressure throughout the entire cavity 4 before the molten metal solidifies, the air in the molten metal is crushed, and the product is densified. Therefore, it is advisable to start increasing the pressure immediately when the filling state reaches completion ( _tf ).
However, even if the control device 30 issues a pressure boost start command at the pressure boost switching position _Pvp corresponding to the position of the plunger 12 at the filling completion time _tf , the pressure boost start time ts is delayed from the filling completion time tf by the time required to detect that the plunger 12 has reached that position, the response time from the issuance of the pressure boost start command until the on-off valve 261 closes and the on-off valve 262 opens, the time required for hydraulic _oil to be supplied from the pressure boost accumulator ₂₃ to the inflow oil chamber C1 and for the plunger 12 to be moved by the injection cylinder 21, and other times required for signal transmission of detection signals and control commands and for control processing. The delay time _Td corresponds to the accumulated time of such electrical and mechanical delays.

Due to the presence of the above-mentioned delay, it is necessary to issue the pressure boost switch command at a preceding switch position _Pp that precedes the pressure boost switch position _Pvp , and the preceding switch position _Pp needs to be set at a position that precedes the pressure boost switch position _Pvp by an amount of displacement of the plunger 12 that corresponds to the delay time _Td . Therefore, the control device 30 calculates the preceding switch position _Pp based on the injection pattern in addition to the pressure boost switch position _Pvp and the delay time _Td .

(Calculation and setting of advance switching position)
An example of a procedure for calculating and setting the preceding switch position _Pp suitable for the injection pattern will be described with reference to Fig. 6 and Fig. 3. The control device 30 calculates and sets the preceding switch position _Pp for each of a plurality of injection patterns used in the injection device 10.
6 shows, in a table _format , the speed switching positions _P0 to _P4 of the injection pattern, and the first section S1, the second section S2, the third section S3, and the fourth section _S4 of the injection stroke divided by the speed switching positions P1 to P3. The subscript n (0, 1, 2, ...) is used to refer to the speed switching positions.
The injection pattern shown in FIG. 3 is characterized in that the plunger 12 is rapidly accelerated to perform filling at high speed, and therefore the length from when the speed is switched to high speed at the speed switching position P2 to the time of filling completion _tf (the displacement of the plunger 12) is short compared to the delay time _Td .

In such an injection pattern, the length from the boost pressure switching position _Pvp corresponding to the filling completion time _{tf to} the speed switching position P3 immediately before the boost pressure switching position _Pvp is shorter than the displacement amount (delay displacement amount) of the plunger 12 corresponding to the delay time _Td . In this case, it is assumed that the leading switching position _Pp is set to lead the boost pressure switching position _Pvp by the product of the delay time _Td and the current speed ( _V1 or _V2 ) of the moving plunger 12. Then, the leading switching position _Pp is displaced toward the rear side of the injection stroke (the side away from the cavity 4) as the speed of the plunger 12 is higher, so that the past leading switching position _Pp is set at the time when the speed of the plunger 12 is switched from low speed to high speed. Even if a boost pressure switching command is issued in the section S3 or section S4 after the switch from low speed to high speed, the delay in the start of boost pressure relative to the filling completion is not sufficiently eliminated.

As in the injection pattern shown in FIG. 3, even in the case where the requirement that the length from the pressure boost switch position _Pvp corresponding to the filling completion time _tf to the speed switch position _P3 immediately preceding the pressure boost switch position _Pvp is shorter than the delay displacement amount of the plunger 12 (hereinafter, requirement A) is met, it is possible to obtain and set the preceding switch position _Pp that correctly reflects the delay time _Td , for example, by the following procedure.
When the injection pattern selected for casting at least satisfies requirement A, the control device 30 sets a leading switching position _Pp that precedes the pressure boost switching position _Pvp by one or more speed switching positions _Pn , as shown below, and outputs a pressure boost start command at the previously set leading switching position _Pp .
The control device 30 judges whether or not the selected injection pattern satisfies the above requirement A, and if so, calculates and sets the preceding switch position _Pp , for example, by steps 1 to 6.

Step 1:
The times T _n (T ₁ to T ₄ ) of the first to fourth sections S1, S2, S3, and S4 of the emission pattern are calculated.
Due to the speed of the injection pattern, the second section S2 and the fourth section S4 correspond to constant velocity sections in which the plunger 12 moves at a constant speed, and the first section S1 and the third section S3 correspond to constant acceleration sections in which the plunger 12 accelerates at a constant acceleration.
The time of the constant velocity section is calculated by equation (1).

The time for the constant acceleration section is calculated using formula (2) based on the basic equation for constant acceleration linear motion.

The acceleration in the first section S1 and the third section S3 does not necessarily have to be constant. For example, the speed may change gradually before and after positions _P0 and _P2 . Even in this case, for example, a speed change position may be determined as an inflection point of the speed, and the time of the section between adjacent speed change positions may be obtained by an appropriate calculation.

Step 2:
By comparing adjacent speed changeover positions P _n and P _n+1 , it is determined between which adjacent speed changeover positions P ₁ to P ₄ the pressure boost changeover position P _vp exists.
In this embodiment, the pressure boost switch position _Pvp exists between the speed switch positions _P3 and _P4 . A circle (◯) is marked in the section SA (here, the fourth section S4) in which the pressure boost switch position _Pvp exists.

Step 3: Calculate the retroactive time T _bn from the pressure boost switch position P _vp to the start point (speed switch position P _n ) of each of the sections S1 to S4.
Here, for the section SA in which the pressure boost switch position _Pvp exists, the time from the pressure boost switch position _Pvp to the immediately preceding speed switch position _Pn is set as _Tvp in equation (3) if the section SA is a constant acceleration section. If the section SA is a constant speed section, it is set as _Tvp in equation (4).

Equation (3) is a modification of the basic equation (5) for uniformly accelerated motion. _VIn is the initial velocity.

The retroactive time T _b3 from the pressure-boosting switch position P _vp to the start point P3 of the fourth section S4 in which the pressure-boosting switch position P _vp exists is T _vp in the formula (4).
The retroactive time T _b2 from the pressure boost switch position P _vp to the start point P ₂ of the third section S3 is the sum of the retroactive time T _b3 and the section time T ₃ calculated in step 1, and is therefore T _b3 +T ₃ .
Similarly, the retroactive time T _b1 to the start point P ₁ of the second section S2 is T _b2 +T ₂ , and the retroactive time T _b0 to the start point P ₀ of the first section S1 is T _b1 +T ₁ .
The processes of steps 1 to 3 are performed by the retroactive time calculation unit 315 (FIG. 5B) of the calculation and setting module.

Step 4:
The section including the leading switch position _Pp is identified from the retroactive time _Tbn from the boost switch position _Pvp to the start point of each section (speed switch position _Pn ) and the delay time _Td . That is, by comparing the position (leading switch position _Pp ) that is a delay displacement amount equivalent to the delay time _Td from the boost switch position _Pvp with each retroactive time _Tbn , the section including the leading switch position _Pp can be identified. A double circle (◎) is marked in the column for the section SB (here, the second section S2) including the leading switch position _Pp .
The process of step 4 is performed by the previous position specifying unit 316 of the calculation/setting module. In step 4, the speed switching position P _n (previous position) immediately before the preceding switching position P _p is specified.

Step 5:
The time _Tp from the start point (immediately preceding position) of the section SB obtained in step 4 to the preceding switching position _Pp is calculated using equation (6).

Step 6:
The preceding switching position _Pp is calculated from the time _Tp obtained in step 5.
The processes in steps 5 and 6 are performed by the preceding switching position calculation unit 317 of the calculation and setting module.
When the section SB is a constant velocity section, the formula (7) is used. When the section SB is a constant acceleration section, the formula (8) is used.

According to the above steps 1 to 6, a leading switch position Pp is calculated based on the injection pattern, which is located beyond one or more _speed switch positions _Pn (here, _P3 , _P2 ) from the pressure boost switch position _Pvp and goes back by the delay displacement amount of the plunger 12 corresponding to the delay time _Td .
The control device 30 associates the calculated advance switching position _Pp with the injection pattern and stores it as data in a setting area in the storage unit 313.

Even if the injection pattern selected for casting does not satisfy requirement A, the advanced switching position _Pp can be calculated in the same manner as in steps 1 to 6. In that case, the section SA where the boosting switching position _Pvp exists is the same as the section SB where the advanced switching position _Pp exists.

When requirement A is not met, the control device 30 can set the leading switch position _{Pp as the product of the speed of the plunger 12 at the filling completion time tf and the delay time Td without following the above steps 1 to 6. Alternatively, an appropriate leading switch position Pp can be set} by constantly updating the leading switch position _Pp as the product of the speed and the delay time _Td based on the speed that changes moment by moment during the movement of the plunger 12.
The control device 30 may be provided with a first setting mode in which it determines whether or not requirement A is met when acquiring the leading switching position _Pp , and if so, sets the leading switching position _Pp by steps 1 to 6, and a second setting mode in which, if not so met, it simply sets the leading switching position _Pp by the product of the speed of the plunger 12 and the delay time _Td .

(Functions and Effects of Setting the Prior Switching Position _Pp )
When the control device 30 has finished the steps of calculating and setting the leading switch position _Pp based on the boost switch position _Pvp , the delay time _Td , and the injection pattern (leading switch position setting step) by, for example, steps 1 to 6, it reads out the leading switch position _Pp associated with the injection pattern selected according to the casting conditions from the setting area of the storage unit 313, and performs the injection filling process A1 while detecting the position of the plunger 12 by the sensor 8 or the like. At this time, it outputs a boost switch command when it is detected that the plunger 12 has reached the leading switch position _Pp (boost switch command output step). By outputting the boost switch command, the on-off valve 261 closes and the on-off valve 262 opens, so that the hydraulic oil flows from the boost accumulator 23 into the inflow oil chamber C1, and the specified casting pressure is applied to the plunger 12.

As shown by the dotted line in Fig. 2, when a pressure increase start command is output at the filling completion time _tf , a delay time _Td occurs from the filling completion time _tf to the actual start of pressure increase, but according to this embodiment, a pressure increase switch command is output at the advance switch position _Pp prior to the filling completion time _tf , so that pressure increase starts at the filling completion time _tf , which is the delay time _Td after the arrival at the advance switch position _Pp , and therefore no delay occurs in the start of pressure increase with respect to the filling completion time _tf . As shown by the solid line in Fig. 2, the casting pressure in this embodiment rises continuously from the end of the injection filling process A1 to the pressure increase process A2.

The delay time _Td can include the time required for detecting the position of the plunger 12 and transmitting the detection signal, and if the pressure boosting switch command is output at the advance switch position _Pp calculated based on the delay time _Td , there is no delay associated with detecting the position of the plunger 12, and the delay from the completion of filling to the start of pressure boosting is eliminated. Even if the delay time _Td varies for each casting cycle, the delay due to the variation in the delay time _Td falls within an allowable limit, and the delay in the start of pressure boosting relative to the completion of filling can be sufficiently eliminated.

By eliminating the delay between the completion of filling and the start of pressure increase, the time required to increase the pressure of the molten metal can be shortened while achieving a speed and pressure waveform that corresponds to the casting conditions, allowing for the production of quality products. In addition, productivity can be improved by shortening the cycle time.

(Another injection pattern)
7 to 9, the setting of the advance switching position _Pp corresponding to another injection pattern and the control of the injection device 10 based thereon will be described.
The injection pattern shown in Fig. 7 is characterized in that after the plunger 12 is rapidly accelerated to the second speed _V2 , the opening of the flow control valve 25 is reduced to brake and decelerate the plunger 12 prior to the natural deceleration of the plunger 12 accompanying the completion of filling. Except for this point, the injection pattern shown in Fig. 7 is similar to the injection pattern shown in Fig. 3.
The plunger 12, while moving at the second speed _V2, starts to decelerate at the speed switching position _P4 , passes through a fifth section S5 (deceleration section) required for deceleration, and is controlled to the third speed _V3 in a sixth section S6 (low speed section before filling completion).

Like the injection pattern shown in FIG. 3, the injection pattern shown in FIG. 7 also satisfies the above-mentioned requirement _A because the length from the pressure boost switch position _Pvp corresponding to the filling completion time tf to the speed switch position _P5 immediately preceding the pressure boost switch position _Pvp is shorter than the displacement amount (delay displacement amount) of the plunger 12 corresponding to the delay time _Td .
7 is selected, if the preceding switch position Pp is set to precede the pressure increase switch position _Pvp by the product of the delay time _Td and the current speed ( _V2 ) of the moving plunger 12, the preceding switch position _Pp will be set at a position that is further back than necessary in consideration of the speed _V3 before the completion of filling. If the start of pressure increase initiated by the pressure increase switch _command issued at the preceding switch position _Pp is earlier than the filling completion time _tf , it will be difficult to control the movement of the plunger 12 to follow the injection pattern, as shown in Comparative Example 2 in FIG. 8, and this will affect the hydraulic pressure of the injection cylinder 21 and the casting pressure.

In Fig. 8, the casting pressure indicated by the dotted line, the head side pressure indicated by the thin dashed line, the rod side pressure indicated by the thin dashed double-dot line, and the speed of the plunger 12 indicated by the thin broken line indicate Comparative Example 2 for this embodiment. Fig. 8 shows B1 to B4, which will be referred to below.
In Comparative Example 2, hydraulic oil flows from the boost accumulator 23 to the head side (inflow oil chamber C1) of the injection cylinder 21 based on a boost switch command output earlier than the charging completion time _tf . At this time, since charging is not completed, the plunger 12 has room to move forward. Therefore, the speed of the plunger 12 increases suddenly (see B1), and the hydraulic oil on the rod side (discharge oil chamber C2) of the injection cylinder 21 is excessively compressed due to the sudden acceleration of the plunger 12, and then is rapidly depressurized (see B2).
After the rod side pressure starts to decrease, the casting pressure increases rapidly, but the pressure oil supplied from the boost accumulator 23 to the injection cylinder 21 is consumed to increase the speed of the plunger 12, so the casting pressure is insufficient for the specified value (see B3). In addition, the rod side pressure typically decreases at the same time as the casting pressure increases, but in Comparative Example 2, the rod side pressure increased to an excessive pressure due to the sudden acceleration of the plunger 12, so it takes extra time for the rod side pressure to decrease (see B4).
Unlike Comparative Example 2, this embodiment can realize velocity and pressure waveforms corresponding to the casting conditions.

According to the control device 30, it is possible to calculate and set the preceding switch position _Pp corresponding to the injection pattern of Fig. 7 in the same manner as in the calculation and setting of the preceding switch position _Pp corresponding to the injection pattern of Fig. 3. An example of the procedure will be briefly described with reference to Fig. 9.
Step 1:
The times T _n (T ₁ to T ₆ ) of the first to sixth sections S1 to S6 of the injection pattern are calculated.
Step 2:
It is determined between which of the adjacent speed switching positions _P1 to _P6 the pressure boost switch position _Pvp exists. In this example, a circle (○) is placed in the column for section SA (sixth section S6) between speed switching positions _P5 and _P6 where the pressure boost switch position _Pvp exists.

Step 3: Calculate the retroactive time _Tbn from the pressure boost switch position _Pvp to the start point (speed switch position _Pn ) of each section S1 to S6. For the section SA in which the pressure boost switch position _Pvp exists, the time from the pressure boost switch position _Pvp to the immediately preceding speed switch position _Pn is set as _Tvp .
Step 4:
The section in which the leading switch position _Pp exists is identified by comparing a position (leading switch position _Pp ) that is a delay displacement amount equivalent to the delay time _Td from the boost switch position _Pvp with each retroactive time _Tbn . A double circle (◎) is marked in the column for the section SB (fourth section S4) in which the leading switch position _Pp exists.

Step 5:
The time _Tp from the start point of the section SB (speed switching position _Pn ) to the preceding switching position _Pp is calculated as _Tbn - _Td .
Step 6:
The preceding switching position _Pp is calculated from the time _Tp obtained in step 5.

As described above, the preceding switch position _Pp can be calculated by going back from the boost switch position _Pvp by the delay displacement amount of the plunger 12 corresponding to the delay time _Td , and set in the control device 30.
The control device 30 reads out the advance switching position _Pp associated with the injection pattern selected according to the casting conditions from the storage unit 313, and performs the injection filling process A1. At this time, a pressure increase switching command is output at the advance switching position _Pp prior to the filling completion time _tf , so that the pressure increase for the molten metal is started at the same time as the filling completion time _tf after a delay time _Td from the time of reaching the advance switching position _Pp . At this time, since the filling of the molten metal into the cavity 4 is completed, the speed of the plunger 12 does not increase with the inflow of the hydraulic oil into the inflow oil chamber C1 on the head side, and the rod side pressure does not increase excessively. As shown by the solid line in FIG. 8, the casting pressure increases continuously from the end of the injection filling process A1 to the pressure increase process A2.

As described above, by outputting a pressure boost switching command at the advance switching position _Pp , which is set based on the pressure boost switching position _Pvp , the delay time _Td , and the injection pattern, it is possible to avoid a decrease in casting quality and productivity due to a delay or advance in the start of pressure boosting relative to the filling completion time _tf , and to provide a quality product.

In addition to the above, the configurations described in the above embodiments can be selected or changed as appropriate without departing from the spirit of the present invention.

1 Die casting machine 2 Fixed mold 3 Movable mold 4 Cavity 5 Mold clamping device 6 Runner 7 Gate 8 Sensor 10 Injection device 11 Sleeve 12 Plunger 13 Molten metal 20 Hydraulic circuit 21 Injection cylinder 22 Filling accumulator 22A, 23A Piston 22B, 23B Filling chamber 23 Pressure boosting accumulator 24 Hydraulic pump 25 Flow rate control valve 25A Servo motor 27 Check valve 28 Storage tank 30 Control device 31 Control device main body 32 Monitor 33 External storage medium 51 Fixed platen 121 Tip 121S Tip area 122 Rod 123 Coupling 210 Piston 210H Piston head 210HS Piston head side area 210R Piston rod 210RS Piston rod side area 211 Cylinder main body 261 to 264 Opening and closing valve 311 Calculation unit 312 Memory 313 Storage unit 314 Input/output unit 315 Retrospective time calculation unit 316 Previous position identification unit 317 Leading switch position calculation unit A Requirement A1 Injection filling process A2 Pressure boosting process C1 Inflow oil chamber C2 Discharge oil chamber P _n , P _n-1 , P _n+1 , P ₀ to P ₆ Speed switch position P _p Leading switch position P _vp Pressure boosting switch position S1 First section S2 Second section S3 Third section (acceleration section)
S4 Section 4 (high speed section)
S5 Fifth section (deceleration section)
S6 6th section (low speed section before filling is completed)
SA, SB section t, T _n , T ₁ to T ₆ hours T _bn , T _b0 to T _b5 retrospective time T _d delay time T _p , T _vp time V _In initial speed V _pn , V _p0 to V _p6 speed t _f time of filling completion t _s time of pressure increase start α, α _n , α _n+1 , α ₁ to α ₆ acceleration

Claims (6)

A control device used to set and control an injection device of a die casting machine, comprising:
The plunger of the injection device changes speed at a plurality of speed switching positions in an injection stroke for injecting molten metal into a cavity,
The control device includes:
an injection pattern capable of identifying the plurality of speed switching positions and the speeds corresponding to the plurality of speed switching positions;
a pressure increase switching position corresponding to a position for switching from injection filling, which injects and fills the molten metal into the cavity, to pressure increase, which increases the pressure of the molten metal in the cavity;
Based on the delay time required for switching from the completion of the filling to the start of the pressure increase,
A preceding switching position can be set by tracing back a delay displacement amount as a displacement amount of the plunger corresponding to the delay time from the pressure boost switching position,
The control device includes:
When the length from the pressure increase switching position to the speed switching position immediately before the pressure increase switching position is shorter than the delay displacement amount, the preceding switching position is set to be located back from the pressure increase switching position by more than one speed switching position, and a command to start the pressure increase at the preceding switching position in the injection stroke is output ; and
The control device includes:
a preceding switch position calculation unit that calculates the preceding switch position from the pressure increase switch position,
The preceding switching position calculation unit is
a retroactive time calculation unit that calculates a retroactive time from the pressure increase switching position to each of the plurality of speed switching positions for each of the speed switching positions;
a previous position specifying unit that specifies a previous position, which is the speed switching position immediately before the preceding switching position, based on the retroactive time and the delay time;
and a preceding switching position calculation unit that converts a time from the previous position to the preceding switching position into the preceding switching position.
Control device for die casting machines.
The injection stroke includes a plurality of sections that are divided by the plurality of speed switching positions,
The injection stroke includes, as the section, an acceleration section in which the moving plunger is accelerated from a first speed, and a high speed section in which the plunger is moved at a second speed after passing through the acceleration section,
The pressure boost switch position is in the high speed section,
A length from the pressure boost switching position to the speed switching position corresponding to the start point of the high speed section is shorter than the delay displacement amount.
The control device for a die casting machine according to claim 1.
The injection stroke includes a plurality of sections that are divided by the plurality of speed switching positions,
The injection stroke includes, as the sections, an acceleration section in which the moving plunger is accelerated from a first speed, a high-speed section in which the plunger is moved at a second speed after passing through the acceleration section, a deceleration section following the high-speed section, and a low-speed section before the completion of filling in which the plunger is moved at a third speed after passing through the deceleration section,
The pressure increase switching position is in the low speed section before the completion of filling,
A length from the pressure increase switching position to the speed switching position corresponding to the start point of the low speed section before the completion of filling is shorter than the delay displacement amount.
The control device for a die casting machine according to claim 1.
The control device includes a storage unit that stores data,
when the control device acquires the preceding switching position for each of the plurality of injection patterns used in the injection device, the control device associates the preceding switching position with the injection pattern and stores the preceding switching position as data in the storage unit.
The control device for a die casting machine according to any one of claims 1 to 3.
A die casting machine control device according to any one of claims 1 to 4 ,
The injection device;
A hydraulic circuit used to drive the injection device.
Die casting machine.
A casting method for injecting and filling a molten metal into a cavity while changing the speed of a plunger provided in an injection device of a die casting machine at a plurality of speed switching positions in an injection stroke of the plunger, comprising:
a first step of setting a preceding switching position that goes back beyond one or more of the speed switching positions from the pressure increase switching position and a delay displacement amount as a displacement amount of the plunger corresponding to the delay time, based on the multiple speed switching positions, an injection pattern that can identify the speeds corresponding to the multiple speed switching positions, a pressure increase switching position that corresponds to a position where a switching is made from an injection filling in which the molten metal is injected and filled into the cavity to a pressure increase in which a pressure of the molten metal in the cavity is increased, and a delay time required for switching from the completion of the filling to the start of the pressure increase;
and a second step of outputting a command to start the pressure increase at the advance switch position in the injection stroke,
In the first step,
calculating a retroactive time from the pressure increase switching position to each of the plurality of speed switching positions for each of the speed switching positions;
A previous position, which is the speed switching position immediately before the preceding switching position, is identified from the retroactive time and the delay time;
The time from the immediately preceding position to the preceding switching position is converted into the preceding switching position.
Casting method.

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