JP2010260070A - Electric injection device for die casting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase an inertia moment of a rotating body such as a rotating shaft of an electric motor, a ball screw shaft, a coupling connecting the rotating shaft and the ball screw shaft in an electric drive type die casting machine injection device. When the rotating body rotates at high speed in response to high-speed injection, the kinetic energy also increases, and then the plunger does not stop immediately after the molten metal is fully filled in the mold cavity, and the molten metal in the mold cavity is excessively compressed. A large pressure (surge pressure) is generated instantaneously. When surge pressure occurs, the mold parting surface opens and burrs are generated, and in severe cases, the mold is damaged.
A servomotor, a motion conversion device that converts the rotational motion of the servomotor into a linear motion, a plunger that injects and fills molten metal in a sleeve into a mold cavity, a linear motion portion of the motion conversion device, and a plan It is set as the structure provided with the surge pressure prevention apparatus connected between jars.
[Selection] Figure 1

Description

  The present invention relates to an electrically driven injection device for a die casting machine for casting an aluminum product, and relates to a device for preventing surge pressure generated in molten metal in a mold cavity during injection filling.

First, a general die casting apparatus and method using a hydraulically driven horizontal die casting machine will be described with reference to FIG.
A die casting machine (casting apparatus) 100 includes a mold apparatus 101 and an injection apparatus 102. In the mold apparatus 101, a fixed mold 118 and a movable mold 119 are attached between a pair of opposed fixed platen 120 and movable platen 121. The fixed mold 118 and the movable mold 119 are closed by a mold clamping device including a fixed platen 120 and a movable platen 121, and a cavity (cavity) 122 is formed therebetween. In a state where the mold clamping force is applied, a molten metal such as aluminum (AL) (molten state at a high temperature) is injected and filled into the cavity 122, and the mold is opened and taken out after cooling and solidification to produce a cast molded product. it can. An injection device 102 is provided to inject and fill the molten aluminum. The fixed platen 120 is provided with a sleeve 117 for storing molten aluminum, and is in fluid communication with the cavity 122 through the fixed platen 120 and the fixed mold 118.

The injection device 102 is provided with an injection cylinder including a hydraulically driven reciprocating piston / cylinder for injecting molten aluminum. The injection cylinder includes an injection cylinder body 116 and a piston 103. Further, the piston 103 has a piston head 115 at the left end in FIG. 7, and a plunger rod 112 is connected to a piston rod 114 integrated with the piston head 115 by an injection coupling 113, and a plunger tip is provided at the tip. 111 is attached. The plunger tip 111 is fitted in the sleeve 117, reciprocates in the sleeve 117, and pumps the molten aluminum in the sleeve 117 to inject and fill the molten aluminum into the cavity 122.
In the embodiment of FIG. 9, since the injection device 102 is a hydraulic type, hydraulic oil (not shown) supplies hydraulic oil to the head side of the cylinder body 116 to drive the piston head 115 and the piston rod 114. . Then, the molten aluminum (AL) stored in the sleeve 117 is pushed by the plunger tip 111 and injected into a cavity (cavity) 122 formed from the fixed mold 118 and the movable mold 119 to be cast.

Here, in order to cast a non-defective product, it is important to appropriately set and control the injection speed and the injection pressure when the molten metal is injected into the cavity.
A general casting injection speed pattern will be described with reference to FIG.
In the hot water supply process before the injection filling process is started, the molten metal is poured into the sleeve 117 by a hot water supply device (not shown), and the injection is started. The tip position of the plunger tip 111 at this time is A. (See figure above figure 10)

From this state, a low-speed injection process is first performed. In this step, it is necessary to advance the plunger tip 111 at a low speed so that the molten metal does not entrain the air inside the sleeve 117. Therefore, stable low speed (VL) control is required. When the plunger tip 111 moves forward and reaches the B position where the molten metal reaches the upper wall of the sleeve 117 and the molten metal surface rises to the vicinity of the gate (when the injection stroke sensor detects that the SL has advanced), the high-speed injection process is switched. It is done. (See the second figure from the top in Fig. 10)
In the high-speed injection process, the plunger tip 111 and the like are accelerated to one machine, and the molten metal is injected and filled into the cavity 122 at a high speed (Vh). This is because the molten metal instantly solidifies when it comes into contact with the surface of the cavity 122 at a low temperature, and it is desirable for the casting of a good product to be filled before solidifying in as short a time as possible. In particular, when the cavity 122 (cast product) is enlarged and complicated, higher speed is required.
Then, immediately before the molten metal is completely filled into the cavity 122, the plunger tip 111 is pushed backward by the molten metal pressure and decelerates. When the plunger tip 111 reaches the C position and the molten metal fills the cavity 122 (full filling), the injection pressure (head pressure of the injection cylinder) increases, so when the measured value of the pressure sensor reaches the set switching pressure Then, it switches to the next boosting holding process. (See the third figure from the top in Figure 10)
In the pressurizing and holding step, burrs are generated when the pressure is increased too early, and shrinkage cavities are generated when the pressure is increased, and the pressure is increased at an appropriate pressure increasing rate. Then, when the set holding pressure is reached, the molten metal pressure is held and controlled for a certain period of time, and the plunger tip 111 is advanced as much as the molten metal solidifies and cools and contracts. (Refer to the bottom figure in FIG. 10)

In recent years, an electric drive system using an electric motor and a ball screw has been developed as a drive apparatus for this injection apparatus. In the electric drive system, the rotary motion of the electric motor is converted into a linear motion by a ball screw, the linear motion portion is connected to the plunger, the plunger is moved forward, and the molten metal is injected and filled.
However, in this electric drive system, the moment of inertia of the rotating body such as the rotating shaft of the electric motor, the ball screw shaft, and the coupling connecting the rotating shaft and the ball screw shaft increases. Also, the kinetic energy increases as the rotating body rotates at high speed in response to high-speed injection. Then, even after the molten metal is fully filled in the mold cavity, the rotation does not stop immediately, and the plunger continues to advance. As shown in FIG. 8, when the plunger advances even after full filling of the molten metal, the molten metal in the mold cavity is excessively compressed, and a large pressure (surge pressure) is instantaneously generated. When surge pressure is generated, the mold parting surface opens, causing burrs, and in severe cases, the mold is damaged.
Furthermore, since the plunger tip receives a large reaction force due to surge pressure, a shocking deceleration force acts on the rotating body that has been rotating at a high speed until then, and the ball screw, thrust bearing, coupling, etc. are damaged. There is also a problem.

  In order to solve these problems, in Patent Document 1, a friction clutch is interposed between the electric motor and the ball screw so that the moment of inertia and kinetic energy of the rotating shaft of the electric motor are not transmitted to the plunger. An electric injection mechanism that limits torque is disclosed.

  Further, in Patent Document 2, in injection filling using an electrically driven injection mechanism, a puddle is provided at the flow end portion of the mold cavity, and the injection speed is set during filling while the molten metal tip flows in the cavity. An electric injection control method for preventing surge pressure by decelerating and further switching to torque control is disclosed.

JP 2007-296550 A JP 2008-126294 A

However, in the mechanism described in Patent Document 1, the moment of inertia of the ball screw shaft mounted on the plunger side relative to the friction clutch is transmitted to the molten metal, so that the cause of the surge pressure still remains.
In the method of Patent Document 2, in a high-speed and high-pressure injection device that requires a large-capacity servomotor, the moment of inertia of a rotating body such as a shaft of the servomotor is increased, so that a puddle for preventing surge pressure is obtained. It is necessary to increase the size, and wasteful use of a large amount of molten metal for one casting occurs. Moreover, if deceleration is applied in the middle of filling, the hot water will fly in the cavity and air will be entrained, resulting in a void defect in the product, resulting in a defective product.

In order to solve the above problems, in the first invention of the present invention,
In an injection device of a die casting machine, a servo motor, a motion conversion device that converts the rotational motion of the servo motor into a linear motion, a plunger that injects and fills molten metal in the sleeve into the mold cavity, and a linear motion of the motion conversion device A surge pressure prevention device connected between the portion and the plunger is provided.
In the second invention,
The surge pressure prevention device incorporates a spring and is configured to prevent surge pressure by elastic deformation of the spring.
In the third invention,
The surge pressure prevention device comprises a hydraulic cylinder, the piston rod of the hydraulic cylinder is connected to a plunger, and a flow path that connects the head chamber and the rod chamber in the hydraulic cylinder is provided inside the piston head and the piston rod. An orifice is formed in the middle of the path, and the head chamber is provided with a compressed spring.
In the fourth invention,
The surge pressure prevention device consists of a hydraulic cylinder, the piston rod of the hydraulic cylinder is connected to the plunger, and the flow path leading to the head chamber and rod chamber in the hydraulic cylinder intersects halfway through the external flow path, and is further connected to the accumulator. The configuration is as follows.
In the fifth invention,
The surge pressure prevention device consists of a double rod type hydraulic cylinder with the same diameter, and the piston rod on one side of the hydraulic cylinder is connected to the plunger and communicates with the plunger side rod chamber and the anti-plunger side rod chamber in the hydraulic cylinder. The flow path is connected in a circuit through a check valve and a relief valve connected in parallel, and when the piston head moves to the plunger side, the hydraulic oil in the plunger side rod chamber passes through the check valve to the anti-plunger side rod chamber. In addition, when the piston head moves to the opposite side of the plunger, the hydraulic oil in the anti-plunger side rod chamber flows into the anti-plunger side rod chamber while receiving resistance through the relief valve. And
In the sixth invention,
The surge pressure prevention device consists of a hydraulic cylinder, the rod of the hydraulic cylinder is connected to the plunger, the head chamber in the hydraulic cylinder is connected to the head chamber of the hydraulic cylinder for surge pressure absorption, and the surge pressure absorbing hydraulic cylinder The piston rod is configured to be movable back and forth by a servo motor and a ball screw.
In the seventh invention,
The surge pressure prevention device consists of a hydraulic cylinder, the rod of the hydraulic cylinder is connected to the plunger, and the head chamber in the hydraulic cylinder is connected to the tank via a flow rate adjustment valve that can continuously adjust the flow rate. And

(1) Even with an electric injection device with high inertia, surge pressure during full filling, where the mold cavity is filled with molten metal, can be prevented, so that generation of burrs and associated damage to the mold can be avoided. is there.
(2) Full filling or high-speed injection filling is possible until just before it, and the quality of the cast product is improved by avoiding the splash of the molten metal and shortening the filling time.
(3) Impact force generated in the servo motor, ball screw, coupling, and bearing as the reaction force of surge pressure is alleviated, and mechanical damage and failure can be avoided.

It is a 1st example of the invention in this application, and is a figure showing the outline of the structure of an electric injection device, and a surge pressure prevention device. It is a figure which shows the outline of the surge pressure prevention apparatus based on 2nd Example of this invention. It is a figure which shows the outline of the surge pressure prevention apparatus based on 3rd Example of this invention. It is a figure which shows the outline of the surge pressure prevention apparatus based on 4th Example of this invention. It is a figure which shows the outline of the surge pressure prevention apparatus based on 5th Example of this invention. It is a figure which shows the outline of the surge pressure prevention apparatus based on 6th Example of this invention. It is a time-axis graph which shows the injection speed and pressure in the injection filling process and the pressure | voltage rise holding process, and the motor speed and torque in the electric injection apparatus of this invention. It is a time-axis graph which shows the injection speed and pressure of an injection filling process and a pressure | voltage rise holding process in the conventional electric injection apparatus, and represents the state which a surge pressure generate | occur | produces. It is a figure which shows the injection apparatus of the conventional hydraulic drive system, and a mold periphery. It is a figure and graph which show the relationship of the position of the plunger in the general die-casting, the state of a molten metal, the injection speed, and a molten metal pressure.

  Hereinafter, six examples according to the present invention will be described with reference to the drawings.

First, a first embodiment will be described with reference to FIG.
The servo motor 15 is connected to a ball screw shaft 18 through a motor coupling 16. The ball screw shaft 18 is supported by a bearing built in the bearing box 17 while being rotatable but constrained in the axial direction. A ball screw nut 19 screwed with the ball screw shaft 18 is fixed to the moving member 14. Further, a surge pressure preventing device 20 is fixed to the moving member 14, and a movable part of the surge pressure preventing device 20 is coupled to the plunger rod 12 by a plunger coupling 13. The plunger tip 11 is fixed to the tip of the plunger rod 12, and the plunger 10 is formed integrally. Since the bearing box 17 is fixed with respect to a stationary platen that holds the mold, it is possible to transmit the radiant power to the molten metal in the mold cavity. The moving member 14 is slidably supported by a linear slide (not shown). Here, a ball screw or the like functions as a motion conversion device that converts rotational motion into linear motion.

  The surge pressure preventing device 20 has a shape of a hydraulic cylinder, and includes a cylinder body 21 as a main body portion, a piston rod 21 and a piston head 23 as movable portions. An impact buffer spring 24 in a compressed state is built in the head chamber of the hydraulic cylinder, and provides resistance to the force with which the piston head 23 is pushed backward (right side in the figure). Further, the rod chamber and the head chamber communicate with the atmosphere via the air breather 25, so that air can enter and exit without putting dust inside. The coupling 13 that connects the plunger 10 and the piston rod 22 may include a load cell so that the injection pressure can be measured. The cylinder body 21 may be integrated with the moving member 14.

Here, when the switching pressure (molten metal pressure) of the condition for switching from the injection filling process to the pressurization holding process is Pc and the diameter of the plunger tip is Dp, the switching force at that time: Fc is
Fc = (π / 4) · Dp ²
It becomes. Therefore, the shock absorbing spring 24 is loaded with a compression force (Fs) that is equal to or slightly larger than Fc (for example, 1.05 to 1.1 times) and is built in. Therefore, the shock absorbing spring 24 does not shrink during injection filling.

The injection filling process and the pressure | voltage rise holding process performed using such an electric injection apparatus are demonstrated using FIG. The upper figure is a time axis graph of the injection speed of the plunger 10 and the injection pressure (melt pressure, metal pressure) received by the plunger tip 11, and the lower figure is a time axis showing the rotation speed and torque of the servo motor. It is a graph.
First, the servo motor 15 starts rotating and reaches a low injection speed. During acceleration at this time, a large motor torque is required to rotate and accelerate a rotating body having a large moment of inertia such as the motor shaft of the servo motor 15, the coupling 16, and the ball screw shaft 18. When the predetermined stroke is advanced, the next high injection speed is reached. However, since it is necessary to accelerate to a high speed in a short time, the motor torque at that time also increases. Between low speed and high speed injection, the motor rotation speed and injection speed are in a proportional relationship.

When the plunger 10 advances and the mold cavity is almost filled with the molten metal, the injection pressure (molten pressure) starts to rise. When the increase control is performed up to the switching pressure (Pc), the servo motor 15 is switched to the torque control (step-up process), and the injection pressure is further controlled to increase. Immediately after this, since the compressive force exceeding Fs starts to act on the shock absorbing spring 24, the shock absorbing spring 24 contracts. Thereby, even if the forward speed of the plunger becomes almost zero, the rotating body such as the ball screw shaft 18 can continue to rotate as much as the shock absorbing spring 24 contracts. Therefore, since the deceleration time and the deceleration rotation angle of the rotating body can be ensured, it can be gradually stopped. As shown in FIG. 7, during the deceleration time, the rotational speed of the servo motor and the injection speed (plunger speed) are not in a proportional relationship.
As a result, the kinetic energy of the rotating body is absorbed by the shock absorbing spring 24. Therefore, since the molten metal in the mold cavity is not excessively compressed, the generation of surge pressure can be prevented, the generation of burrs can be avoided, and the impact force can also be prevented.

  In the boosting step, the motor torque is controlled to increase along the set boosting speed. When the set holding pressure is reached, constant torque holding control is performed. When the set holding time elapses, the holding force is reduced to 0, and the holding process ends. Thereafter, the process proceeds to the next mold opening process. If the required holding pressure cannot be increased only by the torque of the servo motor 15, the moving member 14 may be supplemented with a holding pressure auxiliary device.

  Hereinafter, although the 2nd-6th Example is described, since the basic part of an apparatus, an effect | action, and a control method have many parts which are common in a 1st Example, only a different part is demonstrated.

  A second embodiment is shown in FIG. The hydraulic cylinder of the surge pressure preventing device 20 is filled with hydraulic oil, and the rod chamber 37 is connected to the tank 35 by piping. A protrusion 31 is attached to the head chamber side of the piston head 23, and a disc spring 32 is attached to the outside thereof. The disc spring 32 is compressed and compressed by Fs, and the piston head 23 is pressed against the rod chamber 37 side of the cylinder body 21. A packing is incorporated in the sliding portion to prevent leakage of hydraulic oil. A flow path 33 is provided inside the protrusion 31, the piston head 23, and the piston rod 22, and the head chamber 36 and the rod chamber 37 communicate with each other. A small-diameter orifice 34 is provided in the middle of the flow path 33 to restrict the flow of hydraulic oil.

  When the plunger 10 is pushed with a force equal to or higher than Fs, the disc spring 32 is further compressed, and the hydraulic oil in the head 36 flows into the head chamber 37 through the flow path 33. At this time, the hydraulic oil is squeezed when passing through the orifice 34 in the middle of the flow path 33, pressure is generated on the head chamber 36 side, and the reaction force is increased together with the force of the disc spring 32, so that shock absorption is further improved. Done effectively. Since the volume of the rod chamber 37 increases, hydraulic oil is supplied from the tank 35. In addition, the cylinder stroke must be designed to be longer than the length capable of absorbing shock (absorbing kinetic energy).

Next, a third embodiment will be described with reference to FIG. The hydraulic cylinder of the surge pressure preventing device 20 is filled with hydraulic oil, and the head chamber 44 is connected to the external accumulator side throttle valve 42 and the accumulator 41 via an external flow path. The rod chamber 45 is also connected to the flow path on the head chamber 44 side via the rod side throttle valve 43 by an external flow path. The pressure of the accumulator 41 is a pressure at which the force by which the hydraulic oil pushes the piston head becomes Fs.
If the inner diameter of the cylinder is Ds, the rod diameter is Dr, and the accumulator pressure is Psa,
Fs = (π / 4) · Dr ² · Psa
Thus, Psa can be calculated.

  When the plunger is pushed with a force of Fs or more, the piston moves rearward (right side in the figure), and the hydraulic oil in the head chamber 44 flows out to the rod chamber 45 and the accumulator 41. At this time, since the flow of hydraulic oil is throttled by the accumulator side throttle valve 42 and the rod side throttle valve 43, the pressure in the cylinder becomes Psa or more, and the reaction force against the backward movement of the piston increases. This makes shock absorption more effective because shock absorption takes place while the piston is moving backwards. Also in this case, it is necessary to design the stroke of the cylinder appropriately so that shock absorption (absorption of kinetic energy) can be performed before the piston head reaches the cylinder end.

A fourth embodiment will be described with reference to FIG. The surge pressure preventing device 20 is a double rod type hydraulic cylinder having the same rod diameter, and the anti-plunger side rod chamber 53 and the plunger side rod chamber 54 are filled with hydraulic oil. The anti-plunger side rod chamber 53 and the plunger side rod chamber 54 are externally connected via a check valve 52, and hydraulic oil flows from the plunger side rod chamber 54 to the anti-plunger side rod chamber 53. However, the circuit does not flow in the opposite direction. A relief valve 51 is connected in parallel with the check valve 52, and hydraulic oil flows from the non-plunger side rod chamber 53 to the plunger side rod chamber 54 at a pressure higher than the set pressure, but in the opposite direction. The circuit does not flow.
Therefore, when the plunger moves backward (right side in the figure), the resistance of the set pressure of the relief valve 51 works, and when it moves forward (left side in the figure), it moves without resistance by the action of the check valve 52. Can do. If the set pressure of the relief valve is Psb,
Fs = (π / 4) · (Ds ² −Dr ² ) · Psb
Thus, Psb can be converted.

  When the plunger is pushed with a force equal to or greater than Fs, the piston moves backward (right side in the figure), and the hydraulic oil in the non-plunger side rod chamber 53 flows out to the plunger side rod chamber 54. At this time, the Psb pressure is generated in the non-plunger side rod chamber 53 and the reaction force acts, so that the surge pressure is effectively prevented and the impact is mitigated.

  A fifth embodiment will be described with reference to FIG. The head chamber 62 of the hydraulic cylinder, which is the surge pressure preventing device 20, is filled with hydraulic oil, and the rod chamber 63 contains air so that air can enter and exit through the air breather 61. The rod chamber 63 is connected to the head chamber of the surge pressure absorbing hydraulic cylinder 67, the spring accumulator 64, and the switching valve 65 by piping. The piston rod of the surge pressure absorbing hydraulic cylinder 67 is integrally connected to the nut holder 68 and the ball screw nut 69, and the ball screw shaft 70 screwed with the ball screw nut 69 is coupled to the motor shaft of the servo motor 72 by the coupling 71. It is connected with. The switching valve 65 is connected to the tank 66 in a circuit and is normally closed. However, when the hydraulic oil in the head chamber 62 or the like decreases due to leakage or the like, the solenoid is excited and the valve opens to operate the tank 66. Oil can be supplied to the head chamber 62 and the like.

At the start of the injection process, the servo motor 72 is torque-controlled, and the hydraulic pressure generated in the head chamber of the surge pressure absorbing hydraulic cylinder 67 and the head chamber 62 is adjusted to Psc by the action of the ball screw.
Psc is the cylinder inner diameter Ds and the pressure Psc.
Fs = (π / 4) · Ds ² · Psc
It is the pressure which satisfies. Further, the spring type accumulator 64 has a spring force set so as to balance the force received by the internal piston by the pressure Psc.
When the injection pressure increases and the spray output becomes Fs, the piston head 23 starts moving backward (right side in the figure). At this time, the pressure in the head chamber 62 is maintained at Psc by controlling the torque while the servo motor 72 rotates in the backward direction. When the piston head 23 starts moving quickly and the piston rod or the like is delayed due to the inertia of the piston rod or the like of the hydraulic cylinder 67 for absorbing surge pressure, the piston of the spring type accumulator 64 is retracted (lower side in the figure), and the pressure is It is maintained at approximately Psc. While the piston head 23 moves to the cylinder end, the rotation speed of the rotating body such as the ball screw shaft 18 is gradually reduced to almost zero, so that no surge pressure is generated in the molten metal.

  Finally, the sixth embodiment will be described with reference to FIG. Similar to the fifth embodiment, the head chamber 82 of the hydraulic cylinder, which is the surge pressure preventing device 20, is filled with hydraulic oil, and the rod chamber 83 is filled with air, and air is introduced through the air breather 81. Access is possible. The rod chamber 83 branches in the middle of the piping path, and is connected to the spring accumulator 84, the check valve 85, the flow rate adjustment valve 91, and the pressure sensor 90. The flow rate adjusting valve 91 has a structure in which the opening degree can be freely changed from the closed state to the fully open state by rotation control of the servo motor 92, and the flow rate of the hydraulic oil flowing from the head chamber 82 to the tank 93 can be adjusted. . The check valve 85 is connected to the pump 86, the tank 88, the electric motor 87, and the relief valve 89 in a circuit, and can supply hydraulic oil to the head chamber 82 with an appropriate pressure. Further, the spring type accumulator 64 has a spring force set so as to balance the force received by the internal piston by the pressure Psc.

At the start of injection, the pressure of the hydraulic oil in the head chamber 82 is maintained at Psc by the action of the pump 86, the electric motor 87, and the relief valve 89. Further, due to the action of the check valve 85, hydraulic fluid does not flow from the head chamber 82 side toward the pump 86.
When the injection power exceeding Fc acts on the plunger, the hydraulic oil in the head chamber 82 increases in pressure, so that the pressure is detected by the pressure sensor 9 and the opening of the flow rate adjustment valve 91 is adjusted so that the pressure does not exceed Psc. Adjust and let hydraulic oil escape to tank 93. When there is a response delay of the flow rate adjusting valve 91, the piston of the spring type accumulator 84 moves and the pressure is maintained at approximately Psc.
Due to such an action, a surge pressure is not generated in the molten metal as in the fifth embodiment.

  The above-described embodiment is an example of the present invention, and the present invention is not limited by the embodiment, but is defined only by matters described in the claims, and other embodiments than the above are also possible. It can be implemented.

  It can be used in production plants that cast aluminum products using a die casting machine, and can contribute to improving the quality of cast products and stable operation of casting equipment.

DESCRIPTION OF SYMBOLS 10 Plunger 11 Plunger tip 12 Plunger rod 13 Plunger coupling 14 Moving member 15 Servo motor 16 Motor coupling 17 Bearing box 18 Ball screw shaft 19 Ball screw nut 20 Surge pressure prevention device (hydraulic cylinder)
DESCRIPTION OF SYMBOLS 21 Cylinder main body 22 Piston rod 23 Piston head 24 Impact relaxation spring 25 Air breather 31 Protrusion 32 Disc spring 33 Flow path 34 Orifice 35 Tank 36 Head chamber 37 Rod chamber 41 Accumulator 42 Accumulator side throttle valve 43 Rod side throttle valve 44 Head chamber 45 Rod chamber 51 Relief valve 52 Check valve 53 Non-plunger side rod chamber 54 Plunger side rod chamber 61 Air breather 62 Head chamber 63 Rod chamber 64 Spring accumulator 65 Switching valve 66 Tank 67 Surge pressure absorbing hydraulic cylinder 68 Nut holder 69 Ball screw nut 70 Ball screw shaft 71 Coupling 72 Servo motor 81 Air breather 82 Head chamber 83 Rod chamber 84 Spring type accumulator 85 Check 86 pump 87 electric motor 88 tank 89 the relief valve 90 pressure sensor 91 flow regulating valve 92 servo motor 93 tank 100 die casting machine (casting machine)
DESCRIPTION OF SYMBOLS 101 Mold apparatus 102 Injection apparatus 103 Piston 111 Plunger tip 112 Plunger rod 113 Coupling 114 Piston rod 115 Piston head 116 Injection cylinder main body 117 Sleeve 118 Fixed mold 119 Movable mold 120 Fixed platen 121 Movable platen 122 Cavity (cavity) )

Claims (7)

A servomotor, a motion conversion device that converts the rotational motion of the servomotor into a linear motion, a plunger that injects and fills molten metal in the sleeve into a mold cavity, a linear motion portion of the motion conversion device, and the plunger And a surge pressure preventing device connected between the two, and an electric injection device for a die casting machine. 2. The electric injection device for a die casting machine according to claim 1, wherein the surge pressure preventing device includes a spring and prevents surge pressure by elastic deformation of the spring. The surge pressure preventing device is composed of a hydraulic cylinder, a piston rod of the hydraulic cylinder is connected to a plunger, and a flow path connecting the head chamber and the rod chamber in the hydraulic cylinder is provided inside the piston head and the piston rod. 2. The electric injection device for a die casting machine according to claim 1, wherein an orifice is formed in the middle of the flow path, and a compressed spring is provided in the head chamber. The surge pressure prevention device comprises a hydraulic cylinder, the piston rod of the hydraulic cylinder is connected to a plunger, and the flow path leading to the head chamber and the rod chamber in the hydraulic cylinder intersects in the middle by an external flow path, and the accumulator The electric injection device for a die casting machine according to claim 1, wherein the electric injection device is connected to The surge pressure preventing device comprises a double rod type hydraulic cylinder having the same diameter, and a piston rod on one side of the hydraulic cylinder is connected to a plunger, and a plunger side rod chamber and an anti-plunger side rod chamber in the hydraulic cylinder. The flow path leading to is connected in a circuit via a check valve and a relief valve connected in parallel, and when the piston head moves to the plunger side, the hydraulic oil in the plunger side rod chamber moves through the check valve to the anti-plunger side. It can flow without resistance to the rod chamber, and when the piston head moves to the opposite side of the plunger, the hydraulic oil in the anti-plunger side rod chamber receives resistance through the relief valve and enters the anti-plunger side rod chamber. The electric injection device for a die casting machine according to claim 1, wherein the electric injection device flows. The surge pressure prevention device comprises a hydraulic cylinder, the rod of the hydraulic cylinder is connected to a plunger, the head chamber in the hydraulic cylinder is connected to the head chamber of the hydraulic cylinder for surge pressure absorption, and the surge pressure absorption device 2. The electric injection device for a die casting machine according to claim 1, wherein the piston rod of the hydraulic cylinder can be moved forward and backward by a servo motor and a ball screw. The surge pressure prevention device comprises a hydraulic cylinder, the rod of the hydraulic cylinder is connected to a plunger, and the head chamber in the hydraulic cylinder is connected to a tank via a flow rate adjusting valve capable of continuously adjusting the flow rate. 2. The electric injection device for a die casting machine according to claim 1, wherein the electric injection device is a die casting machine.

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