JP4844209B2 - Hybrid injection device with excellent controllability - Google Patents

Description

  The present invention relates to an injection apparatus such as a die casting machine.

  In die casting of aluminum alloy or the like, a hydraulic die casting machine that conventionally drives an injection plunger with a hydraulic cylinder has been used. In this die casting machine, the pressure and flow rate of the hydraulic oil supplied to the hydraulic cylinder that drives the injection plunger are adjusted to control the injection plunger speed and pressure.

  In such die casting, in order to improve the quality of the cast product, it is important to stably maintain the injection plunger speed. When controlling the speed of the injection plunger driven by the hydraulic cylinder, the hydraulic cylinder Since the flow rate of the hydraulic oil supplied to the engine is controlled by a hydraulic control valve, the response is low and it is difficult to maintain a stable injection plunger speed.

  In addition, when controlling the speed of the injection plunger driven using a hydraulic cylinder, it is difficult to detect the load received by the injection plunger and it is difficult to perform feedback control. Difficult to maintain.

  Furthermore, when hydraulic pressure is used as the drive source for the injection plunger, the energy efficiency is low, and the working environment is deteriorated due to environmental pollution due to hydraulic oil leakage, processing of hydraulic oil waste liquid, and the like.

  Therefore, in order to improve the above points, an injection device has been proposed in which a ball screw mechanism driven by an electric servo motor and a hydraulic cylinder operated by hydraulic pressure of an hydraulic pump and an accumulator are connected in series to an injection plunger (Patent Document). 1-3).

  In the above injection device, an electric servo motor is used to increase the controllability of the injection speed during high-speed injection, and an injection cylinder using a hydraulic cylinder to obtain a sufficiently large pressure increase / holding force during pressure increase / hold pressure Drive. In this drive mechanism, the thrust of the hydraulic cylinder is transmitted to the injection plunger through the shaft of the ball screw, so that the shaft diameter of the ball screw needs to be increased to some extent from the viewpoint of securing mechanical strength. However, this increase in diameter prevents the injection plunger speed from being increased and stabilized.

  Further, while the injection plunger is moved forward by the electric servo motor, it is necessary to supply the hydraulic oil to the hydraulic cylinder following the advance, but the hydraulic circuit for the hydraulic supply follow-up supply becomes complicated, Control itself becomes difficult.

  Furthermore, when the injection pressure is increased and maintained with hydraulic pressure, feedback control based on the rotation speed of the electric servo motor is canceled, and torque in the direction in which the injection plunger is moved forward is always generated. It is necessary to perform control so as not to react with the cylinder, and the overall circuit configuration including the hydraulic circuit must be complicated.

  After all, in the injection device (see Patent Documents 1 to 3), the control circuit and the control method must be complicated. Moreover, this complication does not necessarily lead directly to an increase in speed and stabilization of the injection plunger speed.

  Therefore, in order to improve the above points, there is provided an injection device for driving an injection plunger by connecting an injection plunger in parallel with a ball screw mechanism driven by an electric servo motor and a hydraulic cylinder operated by hydraulic pressure of a hydraulic pump and an accumulator. It has been proposed (see Patent Document 4).

  In the above injection device, the thrust of the hydraulic cylinder is directly transmitted to the injection plunger without going through the ball screw, so there is no need to increase the ball screw shaft diameter, and this improves controllability. Has been.

  However, while the injection plunger is moved forward by the electric servomotor, it is necessary to supply the hydraulic oil to the hydraulic cylinder following the advancement, and when the injection pressure is increased and held by hydraulic pressure, the electric servo is used. It is necessary to cancel the feedback control based on the rotation speed of the motor, always generate torque in the direction to advance the injection plunger, and control so that the control torque of the electric servo motor does not become a reaction force against the hydraulic cylinder. This is the same as the case of the injection apparatus disclosed in Documents 1 to 3, and the control circuit and the control method must be complicated after all.

  Furthermore, since the injection apparatus described in Patent Document 4 includes a hydraulic tank and a hydraulic pump, the scale of the apparatus is increased, the maintainability is deteriorated, and the working environment is deteriorated.

  By the way, in recent years, in die casting, it is required to manufacture a cast product having a complicated shape at high speed and high quality with a high yield. As one method for responding to this, it is considered to use a large and large output motor for driving the injection plunger.

  However, large motors generally have poor responsiveness, and the timing for switching the injection plunger from low speed to high speed is delayed, making it difficult to maintain the quality of the cast product.

  Further, when a large motor is used in, for example, a 350 ton class die casting machine, a large motor of 500 Kw is required for instantaneous output, and a screw feed mechanism with a large pitch (for example, 2000 rpm) is required to increase the speed of the injection plunger. In order to obtain a high speed of 5 m / s, a screw with a pitch of 150 mm is required, and a screw with a pitch of 90 mm is required even at 3 m / s).

  After all, the drive device that drives the injection plunger using a large and large output motor must be large-scale and large-capacity, its controllability is reduced, and a large-scale and large-capacity drive device is used. Then, the inertial mass of the cast product becomes large, and burrs are easily generated in the cast product, so that it becomes difficult to maintain the quality of the cast product.

  There is a demand for high-speed, high-quality, high-yield production of cast products with complex shapes by die casting, and with a simple drive mechanism, controllability and excellent maintainability, as well as small size, There is a need for a lightweight energy-saving injection device.

JP 2000-33472 A JP 2000-84654 A JP 2001-01126 A JP 2006-00887 A

  An object of the present invention is to provide an injection device that drives a plunger with a simple drive mechanism, is small and light, has excellent controllability, and has excellent maintainability.

  In die casting, one of the reasons for complicating the drive mechanism and control method is that it is necessary to supply hydraulic oil to the hydraulic cylinder following the advance while the injection plunger is advanced by the electric motor. .

  The inventor has paid attention to the above, and has intensively studied a hydraulic-electric injection mechanism (hybrid injection mechanism) that does not require hydraulic oil to be supplied to the hydraulic cylinder during advancement of the injection plunger.

  As a result, the present inventor has come up with a new idea of driving the hydraulic control mechanism itself connected to the injection plunger in the advance and retreat direction of the injection plunger. The present invention has been made based on the above idea, and the gist thereof is as follows.

(1) In an injection device that drives a plunger and fills a mold cavity with a molten metal, the hydraulic control mechanism includes a hydraulic cylinder, an accumulator, a high-speed valve, a pressure sensor, and a reservoir tank connected to the plunger. A hybrid injection device excellent in controllability, characterized in that an advance / retreat control mechanism comprising a ball screw mechanism that drives the plunger in the advance / retreat direction of the plunger with an electric servo motor is provided.

(2) In the injection device that drives the plunger and fills the mold cavity with the molten metal, the hydraulic control mechanism including the hydraulic cylinder, the accumulator, the high-speed valve, the pressure sensor, and the reservoir tank connected to the plunger A hybrid injection device excellent in controllability , characterized in that an advance / retreat control mechanism comprising a rack and pinion mechanism that drives an actuator with an electric servo motor in the advance / retreat direction of the plunger is provided .

(3) The electric servo motor constituting the advance / retreat control mechanism is fixed to a stationary plate to which a stationary mold among the molds forming the mold cavity is attached. (1) or (2 ) ) Hybrid injection device with excellent controllability.

  According to the present invention, the injection device itself can be reduced in size and weight, and switching / intensification at the low speed-high speed switching position can be controlled with high responsiveness and high accuracy. Therefore, according to the present invention, a high-quality cast product can be manufactured with a high yield. Moreover, the present invention is excellent in maintainability as it is reduced in size and weight.

  The present invention will be described with reference to the drawings. FIG. 1 shows the basic structure of the hybrid injection device (the device of the present invention) of the present invention. In the figure, a mold cavity 5 is formed as a casting space in a state where a movable mold 4 fixed to the movable platen 2 is closed with respect to a fixed mold 3 fixed to the fixed platen 1.

  An injection sleeve 6 is connected to the fixed mold 3, and a plunger rod 8 having a plunger tip 7 sliding at the tip of the injection sleeve 6 is driven at high speed, and the molten metal held in the injection sleeve 6 is molded into the mold. The cavity 5 is filled. The rear end of the plunger rod 8 constitutes a piston that slides in the hydraulic cylinder 9, and the plunger rod 8 is driven by a hydraulic control mechanism 10 including the hydraulic cylinder 9.

  The hydraulic control mechanism 10 includes an accumulator 11 connected to the hydraulic cylinder 9, a high-speed valve 12 provided at a connecting portion between the hydraulic cylinder 9 and the accumulator 11, a pressure sensor 14 provided at a lower end portion of the accumulator 11, and a rear end portion of the hydraulic cylinder 9. And a pressure sensor 15 provided at the center of the hydraulic cylinder 9.

  The accumulator 11 generates hydraulic pressure in the hydraulic cylinder 9, and controls the supply and discharge of hydraulic oil by adjusting the opening of the high-speed valve 12 to control the generated hydraulic pressure. At this time, the pressure sensor 14 detects the hydraulic pressure in the accumulator 11, and the pressure sensor 15 detects the hydraulic pressure in the hydraulic cylinder 9. The reservoir tank 13 replenishes hydraulic oil in the hydraulic cylinder 9.

  The hydraulic control mechanism 10 is mounted on a mounting plate 17 that can move forward or backward with respect to the stationary platen 1 by an advance / retreat control mechanism 20 configured by, for example, a ball screw mechanism.

  In this way, the advance / retreat control mechanism 20 is not attached to the plunger rod 8 (the hydraulic control mechanism 10 and the advance / retreat control mechanism 20 are arranged in parallel), but is attached to the hydraulic control mechanism 10 itself, that is, the hydraulic control mechanism 10. A feature of the device of the present invention is that a hybrid structure of the advance / retreat control mechanism 20 is adopted.

  The advance / retreat control mechanism 20 shown in FIG. 1 is screwed into the electric servo motor 19 fixed to the lower end of the stationary platen 1, the screw shaft member 21 connected to the rotating shaft of the electric servo motor 19, and the screw shaft member 21. The nut member 18 is fixed to the lower surface of the mounting plate 17.

  That is, by rotating the electric servo motor 19 left and right at a required number of rotations, the mounting plate 17 on which the hydraulic control mechanism 10 is mounted is moved forward at a required speed and at a required speed with respect to the stationary platen 1. Alternatively, the plunger rod 8 (or plunger tip 7) connected to the hydraulic control mechanism 10 can be pushed or pulled out at the required speed and at the required speed in the injection sleeve 6 because it can be moved backward. .

  When the plunger rod 8 (or the plunger tip 7) is pulled out, the plunger lock 22 is locked to the plunger rod 8 to drive the hydraulic control mechanism 10 and / or the advance / retreat control mechanism 20.

  The push-in or pull-out distance (displacement) of the plunger rod 8 (or plunger tip 7) is detected by a displacement sensor 16 provided on the side surface of the mounting plate 17. The detected hydraulic signal and displacement signal are a control device (not shown) that controls the driving of the plunger rod 8 (or the plunger tip 7) by combining the operation of the hydraulic control mechanism 10 and the operation of the advance / retreat control mechanism 20 under optimum conditions. Sent to.

  1 shows a ball screw mechanism that is driven by the electric servo motor 19 as the advance / retreat control mechanism 20 for moving the hydraulic control mechanism 10 forward or backward, but the advance / retreat control mechanism 20 moves the hydraulic control mechanism 10 forward or backward. Any mechanical mechanism may be used as long as it is retracted, and is not limited to the ball screw mechanism. The advance / retreat control mechanism may be, for example, a rack and pinion mechanism.

  Next, a basic driving mode of the device of the present invention shown in FIG. 1 will be described based on the drawings.

  FIG. 2 shows a mode immediately before the start of injection in which a predetermined amount of molten metal M is poured into the injection sleeve 6 from a pouring port (not shown) and a small amount of hydraulic oil is supplied from the reservoir tank 13 to the hydraulic cylinder 9. At this time, the connecting portion between the hydraulic cylinder 9 and the accumulator 11 is closed by the high speed valve 12. The plunger lock 22 is unlocked from the plunger rod 8. In the figure, the pressure sensor and the displacement sensor are omitted.

  Next, the advance / retreat control mechanism 20 is driven by the electric servo motor 19 to advance the mounting plate 17 relative to the stationary platen 1 at a predetermined moving speed. At this time, since the connecting portion between the hydraulic cylinder 9 and the accumulator 11 is closed by the high-speed valve 12, the plunger rod 8 is at a predetermined forward speed that only the advance / retreat control mechanism 20 assumes, and the low-speed injection region in the injection sleeve 6. Will move forward.

  Then, the advance distance of the plunger rod 8 (or plunger tip 7) is detected by a displacement sensor (see FIG. 1), and as shown in FIG. 3, the plunger rod 8 (or plunger tip 7) performs low-speed injection. The plunger rod 8 is moved forward only by the advance / retreat control mechanism 20 until the position for switching to high speed injection (low speed-high speed switching position S) is reached.

  The forward speed may be kept constant until the low speed-high speed switching position S is reached, or may be accelerated from the middle.

  When the plunger rod 8 (or plunger tip 7) reaches the low speed-high speed switching position S, as shown in FIG. 4, the high speed valve 12 is opened, the connecting portion between the hydraulic cylinder 9 and the accumulator 11 is opened, and hydraulic control is performed. The mechanism 10 is actuated to advance the plunger rod 8 (or plunger tip 7) at a high speed. Also at this time, the advance / retreat control mechanism 20 continues to be driven, and the hydraulic control mechanism 10 is advanced while maintaining the forward speed until reaching the low speed-high speed switching position S, or accelerated to advance in the injection sleeve 6. The molten metal M is filled in the mold cavity 5.

  Thus, in the device of the present invention, until the plunger reaches the low speed-high speed switching position S, the hydraulic control mechanism 10 is not driven, but only the advance / retreat control mechanism 20 is driven, and the plunger is switched at the low speed-high speed switching. Since the drive mechanism that drives the hydraulic control mechanism 10 after reaching the position S is employed, the stroke of the plunger rod 8 can be shortened from the conventional stroke.

  That is, in the device of the present invention, the length of the hydraulic cylinder constituting the hydraulic control mechanism and the length of the plunger can be shortened. If the stroke of the plunger rod is short (the length of the hydraulic cylinder is short), the amount of hydraulic oil can be greatly reduced, and energy loss caused when the plunger is driven at low speed is reduced.

  Furthermore, even if the hydraulic cylinder is reduced in diameter, by increasing the charge of the accumulator, the applied pressure can be increased up to about twice even when normal aqueous hydraulic oil is used.

  Thus, in the device of the present invention, the hydraulic control mechanism can be reduced in size and weight while improving the response performance. As a result, the entire injection device is reduced in size and weight. And the maintainability of the apparatus is also improved. The reduction in size, weight, and improvement in maintainability are also structural features of the device of the present invention.

  If the length of the hydraulic cylinder is short, the responsiveness of the plunger rod to the hydraulic pressure is improved. Therefore, the plunger rod is stabilized at the low speed-high speed switching position S at the same time as the hydraulic control mechanism is driven and the required plunger speed is stabilized. Can be obtained.

  The forward speed of the plunger rod 8 (or plunger tip 7) is a forward speed obtained by superimposing the forward speed of the hydraulic control mechanism 10 on the forward speed of the hydraulic control mechanism 10 driven by the forward / backward control mechanism 20, so that the injection sleeve The molten metal M in 6 can be filled into the mold cavity 5 at a stable high speed. This is a functional feature of the device of the present invention that employs a hybrid structure of the hydraulic control mechanism 10 and the advance / retreat control mechanism 20.

  As described above, in the device according to the present invention, since the hybrid structure is adopted, the device itself can be reduced in size and weight, and switching and pressure increase at the low speed-high speed switching position S can be controlled with high responsiveness and high accuracy. As a result, a high-quality cast product can be produced with a high yield. Furthermore, as the apparatus becomes smaller and lighter, the maintainability of the apparatus is improved.

  As shown in FIG. 5, when the filling of the molten metal M is completed and the forward movement of the plunger rod 8 (or the plunger tip 7) stops, the head pressure rises. 12 is a small opening, and the connecting portion between the hydraulic cylinder 9 and the accumulator 11 is narrowed. At this time, the electric servo motor 18 continues to rotate, pressurizes the oil in the hydraulic cylinder 9, applies a preset pressure to the molten metal in the cavity 5, and at the same time, causes the oil to flow back to the previously narrowed connecting portion, The accumulator 11 is charged. When the charging of the accumulator 11 is completed, the high-speed valve 12 is closed and a predetermined pressure is continuously applied with the torque of the electric servo motor 18.

  When the cooling time is up and the injection is completed, the movable mold 4 is opened, the cast product is taken out, the connecting portion between the hydraulic cylinder 9 and the accumulator 11 is shut off as shown in FIG. 6, and the plunger lock 22 is connected to the plunger rod. 8, the advance / retreat control mechanism 20 is driven backward, and the hydraulic control mechanism 10 is moved backward.

  As shown in FIG. 7, when the hydraulic control mechanism 10 reaches the retreat position (injection start position), the hydraulic control mechanism 10 is further retreated a little to prepare for the next injection, and the hydraulic oil corresponding to the leak amount is stored in the reservoir tank. Refill from 13. And after replenishing hydraulic fluid, it returns to FIG. 2 and starts the next die-casting.

  As described above, according to the present invention, a high-quality cast product can be manufactured with a high yield. Moreover, the present invention is excellent in maintainability. Therefore, the present invention has high applicability in the die casting industry.

It is a figure which shows the basic structure of the hybrid injection apparatus of this invention. It is a figure which shows the aspect just before the injection start in this invention. In this invention, it is a figure which shows a mode when a plunger arrives at the low speed-high speed switching position S. In this invention, it is a figure which shows the aspect which advances a plunger rod (or plunger tip) at high speed. In this invention, filling of a molten metal is completed and it is a figure which shows an aspect when advance of a plunger rod (or plunger tip) stops. In this invention, it is a figure which shows an aspect when injection is completed. In this invention, it is a figure which shows an aspect when a hydraulic control mechanism reaches | attains a reverse position (injection start position).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixed board 2 Movable board 3 Fixed mold 4 Movable mold 5 Mold cavity 6 Injection sleeve 6
7 Plunger tip 8 Plunger rod 9 Hydraulic cylinder 10 Hydraulic control mechanism 10
DESCRIPTION OF SYMBOLS 11 Accumulator 12 High-speed valve 13 Reservoir tank 14, 15 Pressure sensor 16 Displacement sensor 17 Mounting plate 18 Nut member 19 Electric servo motor 20 Advance / retreat control mechanism 21 Screw shaft member 22 Plunger lock M Molten metal S Low speed-high speed switching position

Claims (3)

In an injection device that drives a plunger and fills a mold cavity with a molten metal, the hydraulic control mechanism is connected to the hydraulic control mechanism including a hydraulic cylinder, an accumulator, a high-speed valve, a pressure sensor, and a reservoir tank connected to the plunger. A hybrid injection device with excellent controllability, characterized by providing an advance / retreat control mechanism comprising a ball screw mechanism driven by an electric servo motor in the advance / retreat direction. In an injection device that drives a plunger and fills a mold cavity with a molten metal, the hydraulic control mechanism is connected to the hydraulic control mechanism including a hydraulic cylinder, an accumulator, a high-speed valve, a pressure sensor, and a reservoir tank connected to the plunger. A hybrid injection device excellent in controllability, characterized in that an advance / retreat control mechanism comprising a rack and pinion mechanism driven by an electric servo motor in the advance / retreat direction is provided. 3. The controllability according to claim 1, wherein the electric servo motor constituting the advance / retreat control mechanism is fixed to a stationary plate to which a stationary mold among the molds forming the mold cavity is attached . Excellent hybrid injection device.

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