JP2012110929A - Die-casting machine and method for controlling pressure increase in die-casting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die-casting machine capable of manufacturing a high quality cast-molded product by controlling pressure in a pressure increasing step with high accuracy, and a method for controlling pressure increase in the die-casting machine.SOLUTION: In the die-casting machine, when molten metal is injected to fill the inside of a cavity in a closed mold by the forward motion of an injection plunger 15, an electric servomotor 9 is used as a driving source in a low-speed injection step, and a hydraulic driving source is used as a driving source in a high-speed injection step which is carried out next to the low-speed injection step. When a pressure increasing step is carried out after the high-speed injection step, driving of the electric servomotor 9 in the high-speed injection step is controlled so that pressure increase is risen in an early stage. Accordingly, the pressure applied to a cast-molded product which starts to solidify and shrink in the mold can be increased.

Description

  The present invention relates to a die casting machine that injects and fills a molten metal into a mold by advancing an injection plunger, and in particular, a die casting machine including an electric servo motor and a hydraulic drive source as a drive source for advancing an injection blanker, and The present invention relates to a pressure increase control method for a die casting machine.

  In a conventional die casting machine that has been used in the past, a metal material melted in a melting furnace is weighed and pumped by a ladle for each shot, and the molten metal is pumped into a hot water inlet of an injection sleeve and injected. The molten metal is injected and filled into the cavity of the mold at high speed and high pressure by the forward movement of the injection plunger provided in the sleeve so as to be able to advance and retreat, thereby forming the cast molded body.

  The injection process of a die casting machine that injects molten metal into the mold cavity consists of a low-speed injection process followed by a high-speed injection process. In the high-speed injection process, the injection of an injection molding machine that molds plastic products. It is necessary to inject and fill the molten metal into the mold at a high injection speed that is one digit faster than the speed. For this reason, as a drive source in the injection process, an electric servo motor is adopted as a drive source in the low-speed injection process, while in the high-speed injection process, a larger driving force is required. The motor driving force is added, high-speed injection filling is performed in the mold, and immediately after the high-speed injection process, a pressure increasing process is performed to apply a large pressure to the cast molded body that has started to solidify and shrink in the mold. Will be done.

  As related to the above technique, Patent Document 1 uses pressure oil stored in an accumulator (ACC) while performing the same operation as the low-speed injection process for the electric servo motor in the high-speed injection process. The injection plunger is driven forward at high speed, and the molten metal is injected and filled in the mold cavity at high speed. Immediately after that, the electric servo motor is pressure feedback controlled and the electric servo motor is pressurized. A die casting machine that outputs a pressure that matches the pressure increase pressure set in (1) is disclosed.

JP 2006-31505 A

  However, in the conventional technique disclosed in Patent Document 1, in the pressure increasing process, the electric servo motor simply outputs a pressure that matches the pressure increasing pressure set in the pressure increasing process. In addition, it is difficult to quickly raise the pressure increase at the start of the pressure increase process immediately after the high-speed injection process. If it can be performed earlier, it is necessary to control the rising pressure to be increased with high accuracy in accordance with the difference in the shape of the mold, the metal material, and the like.

  The present invention has been made in view of the above problems, and is capable of producing a high-quality cast product by controlling the rising pressure in the pressure-increasing step with high accuracy, and pressure-increasing control of the die-casting machine. It aims to provide a method.

The invention of the die casting machine according to claim 1
When the molten metal is injected and filled into the mold cavity closed by the advance of the injection plunger, an electric servo motor is used as the drive source in the low-speed injection process, and the high-speed injection performed in the next process of the low-speed injection process. In the process, the die casting machine uses a hydraulic drive source as its drive source,
When closing the control valve after completion of the high-speed injection process and shutting off the hydraulic pressure supply to the hydraulic cylinder for advancing the injection plunger, when performing the pressure increasing process started at that timing,
The electric servomotor is driven by speed feedback control along the position axis from the high-speed injection process until the pressure-increasing process is started, and the electric servo motor is driven at the timing when the pressure-increasing process is started. Control that controls the drive of the electric servo motor in the high-speed injection process so that the motor can be controlled by pressure feedback along the time axis and the rise of the boost pressure can be controlled in the initial stage of pressure control in the pressure increase process Means are provided.

The invention of the pressure increase control method of the die casting machine according to claim 2
When the molten metal is injected and filled into the mold cavity closed by the advance of the injection plunger, an electric servo motor is used as the drive source in the low-speed injection process, and the high-speed injection performed in the next process of the low-speed injection process. In the process, a hydraulic drive source is used as the drive source, and the pressure-increasing control method for the die-casting machine in which the pressure-increasing process is executed after the high-speed injection process,
When the control valve is closed after completion of the high-speed injection process, the hydraulic pressure supply to the hydraulic cylinder for advancing the injection plunger is shut off, and the pressure increasing process started at that timing is performed.
The electric servo motor is driven by speed feedback control along a time axis from the high-speed injection process to the start of the pressure-increasing process, and the electric servo motor is driven at the timing when the pressure-increasing process is started. The motor is controlled by pressure feedback along the time axis, and the rising of the pressure increase can be controlled at the initial stage of pressure control in the pressure increase process.

  According to the present invention, during the high-speed injection process, the speed of the electric servomotor that is rotationally driven is controlled by speed feedback control using the position axis, and the drive control is performed along the time axis at the timing when the pressure-increasing process is started. By switching to pressure feedback, using the inertial force and deceleration torque of the electric servo motor, it is possible to control the rising pressure rising pressure at an early stage of the pressure increasing process, and solidify / shrink in the mold. Pressure can be applied to the cast molded body that has begun at an early stage.

  According to the present invention, the pressure increase rise time can be shortened, so that productivity can be improved, the pressure increase rise time can be made faster than the solidification time of the metal material, and the shape of the mold, the metal material, etc. Depending on the difference, the rotation speed of the electric servo motor can be appropriately changed by the control means, so that the rising pressure can be controlled with high accuracy, so that it is possible to achieve the production of a high-quality cast molded body. it can.

It is a perspective view which shows the injection system unit as a principal part of the die-casting machine of this invention. It is explanatory drawing which shows the structure of the injection system unit of a die-casting machine. It is a graph showing a part of the operation process in the injection system unit, the horizontal axis shows time in the upper and lower graphs, in the upper graph, the solid line shows the injection speed, the alternate long and short dash line shows the pressure, In the lower graph, the rotation speed of only the electric servomotor is shown on the vertical axis in a time series corresponding to the upper graph. It is a graph which shows the relationship between the speed of the moving body by the electric servomotor at the time of pressure increase, and pressure increase rise time.

  Embodiments of the present invention will be described below with reference to FIGS. Of course, it goes without saying that the present invention can be easily applied to configurations other than those described in the embodiments without departing from the spirit of the invention.

  An injection system unit 1 as a main part configured in the die casting machine shown in FIGS. 1 and 2 includes a machine base 2, a base member 3 mounted on the machine base 2, a fixed die plate 4, and a base member 3. The holding block 5, the support member 6 held on the fixed die plate 4 and the like, the moving body 7 provided so as to be able to move back and forth on the base member 3, and the holding block 5 and the support member 6 are spanned. It is attached to a plurality of guide bars 8 and a holding block 5 for guiding the moving body 7 to advance and retreat, and is held by an electric servo motor 9 and a holding block 5 that are used as a drive source in a low-speed injection process and a pressure increasing process described later. Then, the rotation of the corresponding electric servo motor 9 is screwed with a pair of ball screws 12 and a ball screw 12 that transmit the rotation of the corresponding electric servo motor 9 via a drive transmission mechanism including a pulley 10 and a belt 11. A pair of accumulators (hereinafter referred to as ACCs) as a driving source for a high-speed injection process that is attached to the moving body 7 and is moved to the moving body 7 and is moved along with the moving body 7. 14) An injection plunger 15 that is integrated with the moving body 7 and also serves as a piston body is attached to a hydraulic cylinder 16 and a fixed die plate 4 that can be moved forward and backward by the hydraulic pressure of the ACC 14 that is a hydraulic power source. The injection plunger tip 15a side at the tip of the injection sleeve 18 is provided so that it can advance and retreat inside, the injection port 18a to which the molten metal provided on the upper portion of the injection sleeve 18 is supplied, the ACC 14 and the first oil chamber of the hydraulic cylinder 16 The injection plunger 15 is disposed on the oil passage connecting the 16a and has a direction switching function and a flow rate control function. Control valve 20 for cutting off the hydraulic pressure supply for advancing, cooler 22 disposed on an oil passage connecting control valve 20 and tank 21, and oil connecting tank 21 and second oil chamber 16 b of hydraulic cylinder 16 The hydraulic pump 23 disposed on the road, the first check valve 25 disposed on the oil path connecting the hydraulic pump 23 and the second oil chamber 16 b of the hydraulic cylinder 16, the control valve 20, and the hydraulic cylinder 16 A pressure sensor 26 disposed on an oil passage connecting the first oil chamber 16a, a second check valve 27 disposed on an oil passage connecting the pressure sensor 26 and the first check valve 25, Based on detection results detected by various sensors, control means 28 for controlling the opening and closing of the control valve 20, driving of the electric servo motor 9 and the like, and controlling the entire die casting machine are configured.

  In the present embodiment, the rotational force of the electric servo motor 9 is transmitted to the ball screw 12 of the ball screw mechanism via the drive transmission mechanism to rotate the ball screw 12, thereby the nut body of the ball screw mechanism screwed to the ball screw 12. By advancing and retreating 13 in the axial direction, the hydraulic cylinder 16 is moved together with the moving body 7 to advance and retract the injection plunger 15. Further, by supplying the pressure oil accumulated in the ACC 14 to the hydraulic cylinder 16 via the control valve 20, a forward force (pressure increasing pressure) is applied to the injection plunger 15, and the injection plunger (hydraulic cylinder is installed). 15) is advanced, and two electric servo motors 9 and two ball screw mechanisms are provided, and the outputs of the two electric servo motors 9 are added together with the moving body 7 to the hydraulic cylinder 16. Since the provided injection plunger 15 is moved in the axial direction, a relatively large thrust can be obtained.

  Next, the operation of the die casting machine will be described with reference to FIG. In the die casting machine of this embodiment, a low-speed injection process, a high-speed injection process, a pressure-increasing process, a cooling process, a biscuit extrusion process, and a reverse process are sequentially performed as a series of molding processes for manufacturing a molded body. In the present embodiment, first, with the electric servo motor 9 as a drive source, the nut body 13 is advanced together with the moving body 7 via the drive transmission mechanism, the ball screw 12 and the like, and the melt supplied to the injection sleeve 18 from the injection port 18a. The metal material is injected and filled at a low speed from the tip of the injection plunger 15 into the mold cavity closed. In the state before injection, the injection plunger 15 is in the last retracted position, and the control valve 20 is in the neutral position. Therefore, a predetermined amount and a predetermined pressure of pressure oil are stored in the oil chamber of the ACC 14, and at this time, the gas in the gas chamber of the ACC 14 is compressed and boosted by the pressure of the oil. The hydraulic pump 23 is in a stopped state other than the step of feeding oil into the second oil chamber 16b of the hydraulic cylinder 16 including the state before injection. Further, in the state before injection, the nut body 13 is disposed at the most retracted position.

  In such a state, when the start timing of the low-speed injection process is reached, the electric servo motor 9 is moved in a predetermined direction and in the low-speed injection process based on a command from the control means 28 that controls the entire machine. It is rotationally driven at a set speed, whereby the moving body 7, the hydraulic cylinder 16, and the injection plunger 15 together with the nut body 13 of the ball screw mechanism are at a low speed (less than 0.5 m / sec. In this embodiment, Set to 0.25 m / sec.). That is, in the low-speed injection process, the electric servo motor 9 is driven and controlled by speed feedback control along the position axis, whereby the low-speed injection process is executed and the molten metal in the injection sleeve 18 reaches the runner portion of the mold. Filling is performed, and air is evacuated from the cavity of the mold. Then, the control means 28 detects the forward position of the injection plunger 15 based on the output from the position sensor (not shown), and at the timing when the injection plunger 15 is advanced by a predetermined distance set in the low speed injection process, the low speed injection is performed. The process is switched to the high-speed injection process (position (a) in FIG. 3).

  Next, at the start timing of the high-speed injection process, the control means 28 is electrically driven at a speed (0.3 m / s in this embodiment) at which the increase in hydraulic pressure in the pressure-increasing process after the high-speed injection process becomes early. The servo motor 9 is driven, the control valve 20 is opened, and the pressure oil stored in the ACC 14 is thereby compressed by the compressed and pressurized gas pressure through the control valve 20 through the first oil chamber ( The forward movement oil chamber) 16a is rapidly fed, and the injection plunger 15 is driven forward with respect to the moving body 7 at a high speed (a speed of 0.5 m / sec or more, and set to 3 m / sec in the present embodiment). . At that time, the oil in the second oil chamber 16b of the hydraulic cylinder 16 is sent to the first oil chamber 16a of the hydraulic cylinder 16 through the second check valve 27 and the oil passage, and the injection plunger 15 is 3 m / sec. Driven forward at high speed, the molten metal is rapidly injected and filled into the mold cavity. Then, the control means 28 detects the advance position of the injection plunger 15 based on an output from a position sensor (not shown), and controls the control valve 20 at a timing when the injection plunger 15 is advanced by a predetermined distance set in the high-speed injection process. The hydraulic pressure supply to the first oil chamber 16a of the hydraulic cylinder 16 is shut off to complete the high-speed injection process (position (b) in FIG. 3).

  When the high-speed injection process is completed, the control valve 20 is switched (closed) to shut off the supply of oil to the hydraulic cylinder 16 and the pressure increasing process is started. Then, the control valve 20 is switched (closed) by the control means 28, and at the timing, the electric servo motor 9 is moved from the speed feedback control along the position axis in the injection process (low speed injection process and high speed injection process) to the time axis. Switch to pressure feedback control along Immediately after that, in the initial stage of the pressure-increasing step, the pressure-increasing pressure quickly rises due to the rotational inertia force and deceleration torque of the electric servo motor 9. And by the said pressure increase process, a big pressure (for example, about 50 tons at the maximum) is given with respect to the metal which began to solidify in a metal mold | die via the biscuit 29 from the injection plunger 15, and with solidification and shrinkage | contraction of a metal, The injection plunger 15 is advanced at a slight speed by a minute amount. And the control means 28 will switch a pressure increase process to a cooling process, if the completion timing of a pressure increase process is detected based on time monitoring.

  Next, in the cooling step, the control means 28 drives and controls the electric servo motor 9 in the forward direction by speed feedback control along the position axis, and advances the moving body 7. As the moving body 7 advances, the injection plunger 15 receives a force in the forward direction. However, since the biscuit 29 comes into contact with the tip of the injection plunger 15, the injection plunger 15 cannot move forward, and against the hydraulic pressure. fall back. Thereby, the pressure oil in the first oil chamber 16a of the hydraulic cylinder 16 is returned to the oil chamber of the ACC 14 through the control valve 20, and the gas in the gas chamber of the ACC 14 is compressed and boosted accordingly. When the control valve 20 is switched by the control means 28 at a timing when a predetermined amount and a predetermined pressure of pressure oil are stored in the oil chamber of the ACC 14 (pressure oil necessary for the high-speed injection process is stored), The means 28 drives and controls the hydraulic pump 23 so that an amount of oil corresponding to the oil flowing out from the second oil chamber 16b of the hydraulic cylinder 16 in the high-speed injection process is supplied from the hydraulic pump 23 to the second oil chamber of the hydraulic cylinder 16. To 16b. Then, an amount of oil corresponding to the oil flowing out from the second oil chamber 16b of the hydraulic cylinder 16 in the high-speed injection process is sent into the second oil chamber 16b of the hydraulic cylinder 16. Then, at the timing when the injection plunger 15 reaches the last retracted position in the hydraulic cylinder 16, the control means 28 stops the hydraulic pump 23, switches the control valve 20 to the neutral position, and further stops the electric servo motor 9. And wait for the end timing of the cooling process. At this time, the tip of the injection plunger 15 is in contact with the biscuit 29.

  When the cooling process is completed, the control means 28 executes the mold opening process, and in synchronism with this mold opening operation, the electric servo motor 9 is driven and controlled in the forward direction by speed feedback control along the position axis. The moving body 7 is moved forward. And in connection with it, the biscuit extrusion process which extrudes the biscuit 29 by the injection plunger 15 is performed synchronizing with mold opening.

  Next, after the biscuit extrusion process is completed, the control means 28 executes a retreating process for retreating the injection plunger 15 at an appropriate timing, and is driven in the retreating direction by the electric servo motor 9 and speed feedback control along the position axis. Control is made to move the moving body 7 backward. And the control means 28 stops the electric servo motor 9 at the timing which the mobile body 7 retracted | retreated to the last retracted position. And many products are manufactured by repeating such a molding cycle.

  As described above, according to the die casting machine of the present embodiment, after the high-speed injection process is completed, the control valve 20 is closed, the hydraulic pressure supply to the hydraulic cylinder for moving the injection plunger 15 forward is shut off, and the timing is started. By controlling the speed of the electric servo motor 9 during the high speed injection process when performing the pressure increasing process, and switching the control of the electric servo motor 9 to pressure feedback along the time axis at the timing when the pressure increasing process is started. Using the inertial force and deceleration torque of the electric servo motor 9, the pressure increase pressure can be increased early in the initial stage of pressure control in the pressure increase process ((d), (d '), (d ") in FIG. 3). It is provided with a control means 28 for controlling the drive of the electric servo motor 9 at the time of the high-speed injection process so that it can be started up. And deceleration torque can be used to control the rising pressure in the pressure-increasing process, and pressure can be applied to the cast body that has started to solidify and shrink in the mold. It is possible to improve the pressure and make the pressure rise rise time faster than the solidification time of the metal material.For example, depending on the difference in mold shape, metal material, etc., the electric servo during the high-speed injection process If the rotation speed of the motor 9 is appropriately changed by the control means 28, as shown in FIG. 4, for example, when the speed of the moving body 7 by the electric servo motor 9 at the time of pressure increase is 0.05 (m / sec) When the pressure rise rise time is 0.08 seconds and the speed of the moving body 7 by the electric servo motor 9 during pressure increase is 0.10 (m / sec), the pressure rise rise time is increased to 0.04 seconds. Electric servo mode during pressure 9 is 0.15 (m / sec), the pressure rising rise time is 0.027 seconds, and the speed of the moving body 7 by the electric servo motor 9 during pressure increase is 0.20 (m Pressure increase rise time is 0.02 seconds, and when the speed of the moving body 7 by the electric servo motor 9 during pressure increase is 0.25 (m / second), the pressure increase rise time is 0. In 016 seconds, when the speed of the moving body 7 by the electric servo motor 9 at the time of pressure increase is 0.30 (m / second), the pressure increase rise time can be shortened to 0.013 seconds. As indicated by the dotted diagonal line in the graph, it is possible to control the rising pressure (rising angle) in the pressure-increasing step with high accuracy, so that a high-quality cast product can be obtained. .

DESCRIPTION OF SYMBOLS 1 Injection system unit 2 Machine stand 3 Base member 4 Fixed die plate 5 Holding block 6 Support member 7 Moving body 8 Guide bar 9 Electric servo motor 10 Pulley 11 Belt 12 Ball screw 13 Nut body 14 ACC (hydraulic drive source)
15 injection plunger 15a injection plunger tip 16 hydraulic cylinder 16a first oil chamber 16b second oil chamber 18 injection sleeve 18a inlet 20 control valve 21 tank 22 cooler 23 hydraulic pump 25 first check valve 26 pressure sensor 27 second sensor Check valve 28 Control means 29 Biscuit

Claims (2)

When the molten metal is injected and filled into the mold cavity closed by the advance of the injection plunger, an electric servo motor is used as the drive source in the low-speed injection process, and the high-speed injection performed in the next process of the low-speed injection process. In the process, the die casting machine uses a hydraulic drive source as its drive source,
When closing the control valve after completion of the high-speed injection process and shutting off the hydraulic pressure supply to the hydraulic cylinder for advancing the injection plunger, when performing the pressure increasing process started at that timing,
The electric servomotor is driven by speed feedback control along the position axis from the high-speed injection process until the pressure-increasing process is started, and the electric servo motor is driven at the timing when the pressure-increasing process is started. Control that controls the drive of the electric servo motor in the high-speed injection process so that the motor can be controlled by pressure feedback along the time axis and the rise of the boost pressure can be controlled in the initial stage of pressure control in the pressure increase process A die casting machine characterized by comprising means. When the molten metal is injected and filled into the mold cavity closed by the advance of the injection plunger, an electric servo motor is used as the drive source in the low-speed injection process, and the high-speed injection performed in the next process of the low-speed injection process. In the process, a hydraulic drive source is used as the drive source, and the pressure-increasing control method for the die-casting machine in which the pressure-increasing process is executed after the high-speed injection process,
When the control valve is closed after completion of the high-speed injection process, the hydraulic pressure supply to the hydraulic cylinder for advancing the injection plunger is shut off, and the pressure increasing process started at that timing is performed.
The electric servomotor is driven by speed feedback control along the position axis from the high-speed injection process until the pressure-increasing process is started, and the electric servo motor is driven at the timing when the pressure-increasing process is started. A pressure-increasing control method for a die casting machine, wherein a motor is controlled by pressure feedback along a time axis so that the rising of a pressure-increasing pressure can be controlled at an initial stage of pressure control in a pressure-increasing step.

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