JP2010201436A - Die casting machine and die casting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die casting machine and a die casting method, wherein the generation of surge pressure is reduced, the generation of burr and the blowing-out of molten metal are prevented, casting quality is improved, structure is simplified, and cost reduction is achieved. <P>SOLUTION: The die casting machine is provided with: a die (101) subjecting a product to cast-molding; an injection cylinder (102) for injecting a molten metal (15) to the die; and a hydraulic device (303) for pressing the injection cylinder under high pressure. The hydraulic device comprises: a piston accumulator (20) for injection feeding hydraulic oil to the injection cylinder; a gas bottle (80) feeding high pressure gas to the piston accumulator for injection; a high speed rate regulation valve (31) regulating the flow of the hydraulic oil from the piston accumulator for injection; a filling force pattern regulation valve (82) controlling the flow of gas; and a pressure detector (50) for feed-back controlling the filling force pattern regulation valve. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a die casting machine (casting machine) and a die casting method, and more particularly to a metal die casting machine and a die casting method for high speed injection.

  A die casting method and a die casting machine (casting machine) for casting using a light metal material such as aluminum are widely used in various fields such as the automobile industry and mold manufacturing. In this die casting method, a molten metal such as aluminum supplied from the pouring port into the plunger sleeve is pumped by a plunger tip and filled into a mold cavity (cavity), whereby a product of a predetermined shape is obtained. Cast. Since light metals such as aluminum alloys have a shorter solidification time than synthetic resins, increasing the injection speed has become important. Further, from the viewpoint of productivity, it is desired to increase the injection speed.

  FIG. 1 is a schematic explanatory diagram of a general die casting machine 100 for light metals such as aluminum. In the description of the present invention to be described later, the configuration of the die casting machine 100 will be described in detail, and only necessary items will be described here. The light metal die casting machine 100 is normally hydraulic, and supplies hydraulic oil to the head chamber of the injection cylinder 102 to drive the piston rod 4, and the aluminum stored in the plunger sleeve 7 via the plunger rod 2. (AL) The molten metal 15 is pushed by the plunger tip 1 and injected into the cavities (cavities) 12 in the molds 8 and 9 for molding.

  In recent die-casting, the gas in the mold is removed by high vacuum (about 5 kPa), thereby eliminating the gas entrapment nest, increasing the injection speed, shortening the filling time, and reducing the shrinkage nest generated inside. It has been reported that the mechanical properties of die castings are significantly improved by the reduction. In recent die casting machines, there is an increasing demand for improving the quality of cast products by shortening the filling time, minimizing the temperature drop of the molten metal. The injection speed in this case is 5 to 7 m / sec, which is about 2.5 times as high as the normal 2-3 m / sec (the above speed values are the actual casting speed (actual punching speed)). This is the speed when the molten metal is being pushed into the mold.) At actual casting sites, if the speed is increased to this point, a surge pressure is generated in the aluminum (AL) molten metal due to the impact at the completion of injection filling. Therefore, the mold clamping device is lost, the mold is slightly opened, and burrs are generated (the molten metal ejected from the gap between the molds is solidified to become burrs). Moreover, hot water squirts occur in severe cases, and in any case, the problem that “production cannot be continued” occurs.

  Therefore, various methods for reducing the surge pressure have been proposed in the past, but all of these proposals have problems. The surge pressure is generated at the high speed shown in FIG. 1 due to the inertia force of the plunger tip 1, the plunger rod 2, the injection coupling 3, the piston rod 4 and the piston head 5, and the cylinder 6 at a high speed. It is generated as a composite of what is generated by the inertia and pressure of the inflowing hydraulic oil. The surge pressure that appears at the moment of completion of filling by the plunger tip 1, the plunger rod 2, the piston rod 4, and the piston head 5 has the greatest influence on the generation of burrs.

  In order to obtain a high-speed actual striking speed performance, a performance exceeding 10 m / sec is required at the time of idling (a state where the molten metal is not put into the sleeve and there is no flow resistance of the molten metal). However, the most severe thing is that this speed needs to be raised at a distance of only 50 mm. Therefore, the injection cylinder and the hydraulic circuit are configured to generate a large pressure when the high speed speed is raised. If the filling is completed as it is, the pressure of the molten metal in the cavity rises at once when filling is completed (surge pressure is generated), the mold is opened, hot water is blown, and a very dangerous state where casting is impossible occurs. To do.

  In order to prevent this, a method of forcibly decelerating the injection piston immediately before completion of filling is adopted (see FIG. 6). (On the other hand, in a machine with a high injection speed of 2 to 3 m / sec, the high speed is low and the pressure at high speed is small, so it balances with the increasing flow resistance of the molten metal in the mold. Because of the slowdown, the impact value at the completion of filling is reduced, and burrs and hot water sprays are less likely to occur.) A machine with a high speed specification exceeding 10m / sec is called an ultra high speed machine. Casting in Japan has an annoying problem. It requires a high degree of accuracy in the amount of hot water supplied by the water heater, and if the amount of hot water is large, filling is completed before it is sufficiently decelerated, surge pressure is generated, and if the amount of hot water is small, the hot water will fly, It becomes discontinuous filling, and poor entrainment of gas occurs when the hot water boundary is bad or bad. FIG. 7 illustrates the mechanism of occurrence of defects when the amount of hot water supply is insufficient and deceleration is effected too quickly. However, raising the hot water supply accuracy of a water heater is a difficult task, and it is difficult to find a solution.

  In the graph of FIG. 6, it is shown how the position of the tip of the plunger tip at the time of filling is changed by increasing / decreasing the amount of the molten metal. The completion position when the amount of molten metal is appropriate (as planned) is shown as an “ideal completion position” (broken line). When the amount of hot water supply is large, the filling completion position is away from the gate, and thus is a position indicated by a one-dot chain line. When the amount of hot water is small, the filling completion position is close to the gate, and thus becomes a position indicated by a two-dot chain line. As described above, the filling completion position differs depending on the increase / decrease in the amount of the molten metal, and accordingly, there arises a problem that a surge pressure is generated or the molten metal tip flies. On the other hand, it is difficult to increase the hot water supply accuracy of the water heater, and it is not easy to grasp the amount of hot water supply, so it is difficult to grasp the amount of hot water and adjust the deceleration start position.

  The applicant of the present application has already proposed a proposal (see, for example, Patent Document 1) that includes a high pressure accumulator and a low pressure accumulator as a method for reducing surge pressure regardless of the amount of hot water supply. However, the present invention is different from this scheme.

  The applicant of the present application has proposed another proposal (for example, see Patent Document 2). In this scheme, high-pressure gas filled in a gas bottle is used as a hydraulic driving force for driving the injection cylinder 102 during high-speed injection. When the hydraulic oil is pressed with high-pressure gas, the high-pressure gas expands, so that the gas pressure decreases. And the surge pressure of the molten metal generated near the stroke end of the injection cylinder is suppressed by using the pressure drop of the driving gas pressure, and the generation of the surge pressure is prevented. In Patent Document 2, two proposals have been proposed. In the first proposal, the capacity of the gas bottle can be changed, and the optimum gas bottle capacity is selected according to the type of casting. In the second plan, a variable throttle valve is provided on the outlet side of the gas bottle to adjust the throttle opening. Both proposals are intended to realize high-speed injection speed, prevent generation of surge pressure, and enable high-quality product molding.

  FIG. 8 shows the conventional hydraulic circuit. In the hydraulic circuit of FIG. 8, a variable throttle valve 82 is provided on the outlet side of the gas bottle (the above-mentioned second plan). Since the hydraulic circuit of FIG. 8 has many common points with the hydraulic circuit of the present invention to be described later, the description thereof is minimal. In FIG. 8, the piston of the injection piston accumulator 20 is moved to supply hydraulic oil to the head chamber 16H of the injection cylinder 102, and the injection piston 4 is driven to perform high-speed injection. The gas chamber 217 of the injection piston accumulator 20 communicates with the gas bottle 80. Between the gas chamber 217 and the gas bottle 80, a variable throttle valve that is preferably motor-driven is provided. This throttle valve is called a filling force pattern adjustment valve 82. In the high-speed injection stage, by adjusting the opening degree of the filling force pattern adjusting valve 82, a pressure drop due to the flow path resistance is caused to prevent the generation of surge pressure.

  In the hydraulic circuit 503 of FIG. 8, the boosting piston accumulator 23 is provided, and when the transition from the high-speed injection stage to the boosting stage is performed, the boosting on-off valve 35 is opened, and hydraulic oil from the boosting piston accumulator 23 is injected into the injection cylinder 102. Is introduced into the head chamber 16H, and the pressure acting on the molten metal is increased (ie, increased). The reason for switching to the boosting circuit upon completion of the high-speed injection is to quickly increase (pressurize) the pressure drop due to the pressure drop of the gas line from the gas bottle 80 to a predetermined pressure, and this pressure boosting speed is slow. When the pressure is low, solidification of the molten metal begins and causes nest formation. FIG. 4 shows the change over time in the return of the gas pressure of the piston accumulator for injection when the gas amount is reduced by the filling force pattern adjustment valve 82 in the hydraulic circuit of FIG.

  When the target output (pressure) is reduced, the opening of the throttle valve is about 5 to 10 mm, which is a dotted line portion in FIG. The pressurization time required for the die casting machine is 20 to 50 msec. However, in this case, the gas pressure recovery time of the injection piston accumulator is 30 to 200 msec, which is not in time. Therefore, in the prior art hydraulic circuit of FIG. 8, a boosting piston accumulator is provided separately, and the circuit is switched to the boosting side just before the high-speed filling is completed to increase the boosting capability. In that case, in order to protect the continuity of the injection capacity, control is performed such that the boosting on-off valve is opened and the injection on-off valve is closed after a short delay. If the on-off valve for injection is closed too early, the injection pressure drops once and then rises again, causing pressure discontinuity. Also, if the injection on / off valve is closed too late, the pressure increase time delay becomes large, and a problem occurs in the quality of the cast product, such as a sinkhole. In this conventional hydraulic circuit, it is necessary to obtain an optimum value of the delicate switching delay time and to perform control so that the variation is minimized.

Japanese Patent Application No. 2006-290165 Japanese Patent Application No. 2007-229335

The present invention has been made in view of the above-described circumstances, and in a die casting method or die casting machine capable of high-speed injection molding, the generation of surge pressure is reduced to prevent generation of burrs, hot water spray, or jumping of the hot water tip. Furthermore, the object is to minimize the variation in casting quality and to improve the complicated control for that purpose.
It is another object of the present invention to simplify the apparatus by eliminating a boosting piston accumulator and the like, thereby reducing the cost.

  In order to achieve the above-mentioned object, a die casting machine (100) according to a first aspect of the present invention moves a mold (101) for casting a product and a piston (13) included in the mold (101). An injection cylinder (102) for injecting molten metal (15) into the mold (101), and when hydraulic oil is supplied, thereby causing the piston (13) to advance toward the mold (101). An injection cylinder (102) comprising a head chamber (16H) and a rod chamber (16R) which, when supplied with hydraulic oil, causes the piston (13) to retract away from the mold (101). And a hydraulic device (303, 403) for supplying hydraulic oil to the injection cylinder (102). The hydraulic device (303, 403) is an injection piston accumulator (20) that supplies hydraulic oil that presses the piston (13) of the injection cylinder (102) to the injection cylinder (102), and that operates to store the hydraulic oil. An injection piston accumulator (internally formed) is formed by an oil chamber (218) and a gas chamber (217) for containing gas being hermetically partitioned by the piston (211) of the injection piston accumulator (20). 20) and; the piston of the injection piston accumulator (20) installed in fluid communication with the gas chamber (217) of the injection piston accumulator (20) and supplying gas to the gas chamber (217). (211) is pressed to drive the hydraulic oil, the gas bottle (80); and the injection piston accumulator (20) A filling force pattern adjusting valve (82) disposed between the gas chamber (217) and the gas bottle (80) to adjust the gas flow; and the injection speed of the piston (13) of the injection cylinder (102) And a pressure detector (50) for detecting the pressure of the hydraulic oil chamber (218) of the injection piston accumulator (20). The filling force pattern adjustment valve (82) is a servo motor valve whose opening degree is variable and can be set, and the opening degree of the filling force pattern adjustment valve (82) is fed back by the pressure detected by the pressure detector (50). It is possible to control and adjust the filling force of hydraulic oil to the injection cylinder (102).

  In a preferred embodiment, the hydraulic device (303, 403) further comprises an injection speed detector for detecting the speed of the piston (13) of the injection cylinder (102) in order to detect the injection speed of the molten metal (15). The high-speed speed adjusting valve (31) can be feedback-controlled by the injection speed to adjust the opening degree of the high-speed speed adjusting valve (31). Further, the high speed speed adjusting valve (31) is arranged on either the inlet side of the head chamber (16H) of the injection cylinder (102) or the outlet side of the rod chamber (16H) of the injection cylinder (102).

  Another embodiment of the present invention provides a die casting method using the die casting machine (100) described in the first embodiment. In this die casting method, the molten metal (15) in the injection cylinder (102) is pressed at a low speed, and the molten metal (15) in the injection cylinder (102) is pressed at a high speed to mold (101). Injecting into the high-speed injection stage, pressurizing the molten metal (15) in the mold (101) to a predetermined pressure, maintaining the pressure of the molten metal (15) pressurized in the pressurizing stage and the pressurizing stage; A pressure holding stage. In the pressurization stage of the die casting method, the opening degree of the filling force pattern adjustment valve (82) is determined by using the pressure detected by the pressure detector (50) as a feedback signal and a preset hydraulic oil pressure rise pattern and final value. Feedback controlled to follow the pressure. Further, the hydraulic device (303) further includes an injection speed detector for detecting the speed of the piston (13) of the injection cylinder (102) in order to detect the injection speed of the molten metal (15). In the high-speed injection stage, the opening degree of the high-speed speed adjusting valve (31) is preferably feedback controlled so that the injection speed becomes a predetermined value.

In particular, in a die casting casting method or die casting machine (casting machine) capable of high-speed injection molding, feedback control of the high-speed speed adjustment valve and filling force pattern adjustment valve is used to use the pressure drop of the driving hydraulic oil due to gas expansion Without starting complicated control, start up at high pressure at a high pressure in a short time, start up the high speed in a short time, reduce the pressure to the optimum value before filling, and naturally by the flow resistance of the molten metal in the mold Deceleration reduces the high speed value, mitigates impact at the completion of filling, enables high speed injection molding, suppresses the occurrence of surge pressure of molten aluminum in the mold cavity at that time, Prevents hot water spraying or hot water splashing.
Furthermore, even if there is a variation in the amount of hot water supplied to the molten metal, the plunger is naturally decelerated just before the filling completion position due to the flow resistance of the molten metal flowing into the mold, so the deceleration position in the mold is the same. Thus, it is possible to suppress the generation of surge pressure, and to prevent the occurrence of burrs, spraying of hot water, or jumping of hot water.

  The boosting piston accumulator and its surrounding control valves, which were necessary in the past, can be deleted. In addition, since the components and valves are no longer necessary, a complicated control method can be improved and the cost of the apparatus can be reduced.

  In the above description of the present invention, symbols or numbers in parentheses () are attached to show correspondence with the embodiments described below.

FIG. 1 is a schematic explanatory view of a die casting machine (casting apparatus) according to a first embodiment of the present invention, and shows a configuration in the vicinity of a die and an injection cylinder of the die casting machine. FIG. 2 is a system diagram of the hydraulic device for the die casting machine according to the first embodiment of the present invention. FIG. 3 is a system diagram of a hydraulic apparatus for a die casting machine according to the second embodiment of the present invention. FIG. 4 is an explanatory diagram for changing the filling force pattern according to the change in the opening degree of the filling force pattern adjusting valve (change in the gas pressure recovery time of the injection piston accumulator). FIG. 5 shows a chart showing temporal changes in injection speed, injection pressure, etc., and states of piston rods, valves, etc. at that time in the first embodiment. FIG. 6 is an explanatory diagram of an injection speed and the like of injection molding with an ultra-high injection speed, and shows a positional relationship at the end of injection with respect to the amount of hot water. FIG. 7 is an explanatory diagram illustrating the mechanism of the occurrence of defects when the amount of hot water supply is insufficient and deceleration is completed before filling is completed. FIG. 8 is a system diagram of a hydraulic device of a conventional die casting machine.

  Hereinafter, a die casting machine (apparatus) according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic explanatory view of a portion near a mold 101 and an injection cylinder 102 of a general die casting machine 100 for light metal such as aluminum as already described, and the die casting machine 100 of the present invention is also a similar mold. 101 and an injection cylinder 102 are provided. FIG. 2 is a system diagram of the first embodiment of the hydraulic circuit of the hydraulic device 303 of the die casting machine 100 according to the present invention.

  First, referring to FIG. 1, a mold 101 and an injection cylinder 102 of a die casting machine (casting apparatus) 100 of the present invention are schematically shown. 1 has already been described in the description of the prior art, but will be described in more detail here. The die casting machine 100 of FIG. 1 usually casts light metal products such as aluminum. A die casting machine (casting apparatus) 100 includes a mold 101 and an injection cylinder 102. In the mold 101, a fixed mold 8 and a movable platen 11 are disposed between a pair of opposed fixed platens 10 and a movable platen 11. A movable mold 9 is provided, and the fixed mold 8 and the movable mold 9 are engaged as shown in FIG. 1 to form a cavity 12 between them, and aluminum (AL) is formed in the cavity 12. The molten metal 15 is injected and filled to produce a cast product. In order to inject the molten aluminum 15, an injection cylinder 102 is provided, and the fixed platen 10 is provided with a plunger sleeve 7 in which the molten aluminum 15 is stored. The plunger sleeve 7 includes the fixed platen 10 and the fixed platen 10. Passes through the mold 8 and is in fluid communication with the cavity 12.

  In the present embodiment, the injection cylinder 102 is a hydraulically driven reciprocating piston / cylinder for injecting molten aluminum. The injection cylinder 102 includes a cylinder 6 and a piston 13. The piston 13 is engaged with the plunger sleeve 7 as shown in FIG. The piston 13 includes a piston head 5 at the left end in FIG. 1, and a plunger rod 2 is connected to a piston rod 4 integrated with the piston head 5 by an injection coupling 3. It is attached. The plunger tip 1 is fitted in the plunger sleeve 7, reciprocates in the plunger sleeve 7, and pumps the molten aluminum 15 in the plunger sleeve 7 to inject and fill the molten aluminum 15. In the present embodiment, since the injection cylinder 102 is hydraulic, the hydraulic oil is supplied to the head side of the cylinder 6 to drive the piston head 5 and the piston rod 4, and the aluminum stored in the plunger sleeve 7. (AL) The molten metal 15 is pushed by the plunger tip 1 and injected into the cavities (cavities) 12 in the fixed molds 8 and 9 for casting.

  FIG. 2 schematically shows a hydraulic circuit of the hydraulic device 303 according to the first embodiment of the present invention that drives the injection cylinder 102. An injection piston accumulator (ACC) 20 capable of discharging a large flow rate for high speed injection is provided in fluid communication with the connection port line of the head chamber 16H of the injection cylinder 102 via the outlet switching valve 21. Generally, a cylindrical injection piston accumulator 20 is airtightly divided into two chambers by a piston 211 that reciprocates while sliding in the piston accumulator 20, and one of them is an operation in which hydraulic oil is accommodated. An oil chamber 218 is provided, and the other is a gas chamber 217 in which gas is accommodated. The gas chamber 217 is supplied with high-pressure gas from the gas bottle 80 and presses the piston 211 to supply the hydraulic oil in the hydraulic oil chamber 218 to the hydraulic circuit of the hydraulic device 303, that is, here, finally, the head chamber of the injection cylinder 102. Supply to 16H. In the present embodiment, the gas chamber 217 is in fluid communication with the gas bottle 80 via the filling force pattern adjustment valve 82 as shown in FIG. In the hydraulic apparatus 303 of the present embodiment, as shown in FIG. 2, the head chamber 16H of the injection cylinder 102 is further in fluid communication with the tank 40 via the injection switching valve 26. The injection switching valve 26 is preferably an electromagnetic switching valve having three switching positions. As shown in FIG. 2, the connection port on one side is a connection port (inlet side) of the head chamber 16H of the injection cylinder 102. The other side connection port is connected to the tank 40.

  The connection port (outlet side) line of the rod chamber 16R of the injection cylinder 102 is in fluid communication with the tank 40 or the pump pressure supply port 55 via a high speed speed adjustment valve 31 that controls the injection speed (meter-out circuit). Alternatively, the high-speed speed adjusting valve 31 for controlling the injection speed may be installed on the upstream side (inlet side) of the injection cylinder 102 (that is, between the injection cylinder 102 and the injection piston accumulator 20) (meter).・ In-circuit). In the present embodiment, a pressure detector 50 is provided on the outlet side (downstream) of the hydraulic oil chamber 218 of the injection piston accumulator 20, and the hydraulic oil pressure on the outlet side of the hydraulic chamber of the injection piston accumulator 20 is provided. Is detected. The detected pressure (hydraulic pressure) is sent as a pressure signal to a control device (not shown), and a feedback signal is sent to the filling force pattern adjustment valve 82.

  Each valve of the hydraulic device 303 shown in FIG. 2 will be described. The high speed speed adjusting valve 31 is preferably a motor-driven valve whose opening degree can be continuously changed from the fully open position to the fully closed position. The filling force pattern adjustment valve 82 is a valve for adjusting the amount of gas supplied to the injection piston accumulator 20, and is preferably a servo valve that can be adjusted from an open state of 10 to 20 msec to a fully closed state. The injection switching valve 26 has already been described, and the three positions are a flow path closed position, a forward flow path open position, and a cross flow path open position, respectively, as schematically shown in FIG. The outlet switching valve 21 is preferably an electromagnetic switching valve that switches between opening and closing.

  Next, the operation of the die casting machine 100 and its hydraulic device 303 according to the present embodiment will be described. The overall operation of the die-casting machine 100 is the same as that of a normal die-casting machine, and thus will be outlined. First, the molten AL 15 is supplied to the plunger sleeve 7, and then the injection operation is performed without delay so that the molten metal temperature does not decrease. First, the molten metal 15 is pushed toward the cavity 12 of the mold 101 by the piston 13 at a low speed (low speed injection stage). In this embodiment, the piston 13 is driven by opening the filling force pattern adjusting valve 82 and opening the outlet switching valve 21 to adjust the throttle opening of the high speed speed adjusting valve 31. The operation is performed by moving the piston 211 of the injection piston accumulator 20 by the pressure of the gas bottle 80 and supplying the hydraulic oil to the head chamber 16H. Further, the adjustment of the throttle opening degree (small opening degree) of the high-speed speed adjusting valve 31 is performed by detecting the speed of the injection piston 4 with an injection speed detector (not shown) and controlling the control apparatus ( (Not shown) through feedback control. The opening degree of the filling force pattern adjustment valve 82 is set to an opening degree (a predetermined opening degree) that provides a desired injection pressure. After the piston 13 has moved by a predetermined stroke or when the piston 13 has reached a predetermined position, the low-speed injection stage is switched to the high-speed injection stage.

  Next, the opening speed (large opening degree) of the high-speed speed adjusting valve 31 is also feedback-controlled through a control device (not shown) so that the predetermined high-speed injection speed is obtained. To drive the piston 13 (high-speed injection stage). In this high-speed injection stage, the cavity 12 is filled with the molten metal 15. Next, by adjusting the filling force pattern adjusting valve 82 and supplying a high pressure gas from the gas bottle 80 to the gas chamber 217, a higher pressure hydraulic oil is introduced into the head chamber 16H from the injection piston accumulator 20. The pressure in the cavity is increased to a predetermined pressure in a predetermined time (pressure increase stage). In the pressure increasing stage, the high speed speed adjusting valve 31 is adjusted to be fully opened, and the filling force pattern adjusting valve 82 uses the pressure detected by the pressure detector 50 as a feedback signal to set a preset pressure increase pattern and a final value. Feedback control is performed to achieve pressure. The novel configuration of the present invention mainly functions in this boosting stage.

  Next, a predetermined pressure is held for a predetermined time (pressurization holding stage). In the pressurization and holding stage, the filling force pattern adjustment valve 82 is in principle fully closed, but when the pressure detector 50 detects a pressure drop, it is opened slightly to control the pressure. The high speed speed adjustment valve 31 is set to be fully open. Thereafter, the product is taken out (mold opening stage). After the pressurizing and holding stage, the high speed speed adjusting valve 31 is adjusted to supply hydraulic oil from the pump pressure supply port 55 to the rod chamber 16R of the injection cylinder 102, and the injection piston 4 is moved backward to return to the origin. After that, the filling force pattern adjustment valve 82 is opened to a desired opening, and hydraulic oil is supplied from another hydraulic pressure supply line 56 to the hydraulic oil chamber 218 of the injection piston accumulator 20 to accumulate the gas bottle 80. The above is the outline of the injection molding process. The series of controls described above is performed via a control device (not shown).

  According to the present embodiment, high-speed injection speed is realized by feedback control of the high-speed speed adjustment valve 31 and the filling force pattern adjustment valve 82 in accordance with the characteristics (cavity capacity and projected area) of the mold to be cast. At the same time, the pressure drop (drop) generated by gas expansion that occurs during high-speed injection is used for natural deceleration to prevent the occurrence of surge pressure of the molten metal. And boosting can be performed.

  In the above-mentioned prior application (Patent Technical Document 2) of the applicant, in actual operation, the injection speed, injection pressure change pattern, final filling force (hydraulic pressure on the head chamber side of the injection cylinder: Ph), it is described that it is preferable to perform trial hitting as a method for determining the holding pressure and the like. However, since this is the same in the present application, details of this trial hitting are omitted.

FIG. 5 shows a chart showing temporal changes in the injection speed (v), injection pressure (PH), etc., and states of the piston rod, each valve, etc. at that time in the present embodiment. In FIG. 5, PH represents the injection pressure, and Pm represents the holding pressure. The low-speed injection stage is between times t0 and t1, the high-speed injection stage is between times t1 and t2, the boosting stage is between times t2 and t3, and the pressurization holding stage is between times t3 and t4. is there. At t2, switching from the high-speed injection stage to the boosting stage (that is, switching of the high-speed speed adjusting valve 31 and switching of the filling force pattern adjusting valve 82) is performed by the pressure detectors provided in the head chamber 16H and the rod chamber 16R. The detection pressure (Ph) is used. Since the operation of the injection piston 4, the operation of each valve, etc. can be fully understood by referring to FIG. 5, detailed description will be omitted. The injection pressure (PH) in the case of meter-out control can be expressed as follows:
Injection pressure (PH) = Ph− (Sr / Sh) × Pr
Here, Ph: pressure in the head chamber 16H, Pr: pressure in the rod chamber 16R, Sh: area on the head chamber 16H side, Sr: area on the rod chamber 16R side.

  FIG. 3 is a system diagram of a second embodiment of the hydraulic apparatus of the die casting machine 100 according to the present invention. Hereinafter, only differences from the first embodiment will be described. The hydraulic device 403 according to the second embodiment differs from the hydraulic device 303 according to the first embodiment in the position of the high speed speed adjustment valve 31. That is, in the hydraulic circuit of the hydraulic device 403 in FIG. 3, the high-speed speed adjusting valve 31 is installed on the inlet side (upstream) of the head chamber 16H of the injection cylinder 102 (meter-in circuit), while FIG. In the hydraulic circuit of the hydraulic device 303, the high-speed speed adjusting valve 31 is installed on the outlet side (downstream) of the rod chamber 16R of the injection cylinder 102 (meter-out circuit). In accordance with this difference in configuration, in the second embodiment shown in FIG. 3, the injection switching valve 26 is arranged on the outlet side of the rod chamber 16R, and the system to the tank 40 and the pump pressure supply port 55 is also adapted accordingly. Has been changed.

  In the second embodiment of FIG. 3, when the rod chamber 16R is conducted to the tank 40, the rod chamber pressure Pr is substantially zero, so the injection pressure PH is equal to the head chamber pressure Ph. The other configuration of the hydraulic device 403 is basically the same as that of the hydraulic device 303 of the first embodiment shown in FIG. 2, and the operation method of the die casting machine 100 is substantially the same as that of the first embodiment. It is.

Next, effects and operations of the above embodiment will be described. The following effects can be expected from the die casting machine according to the first embodiment of the present invention.
In particular, in the die casting method or die casting machine (casting machine) capable of high-speed injection molding, feedback control of the high-speed speed adjustment valve 31 and the filling force pattern adjustment valve 82 is performed, so that the pressure of the driving hydraulic oil due to gas expansion Using drop, without complicated control, start up at high pressure and start up high speed in a short time, lower the pressure to the optimum value before filling, and flow of molten metal in the mold Natural deceleration by resistance reduces the high-speed speed value, alleviates the impact when filling is completed, enables high-speed injection molding, and suppresses the generation of surge pressure of molten aluminum in the mold cavity at that time. Prevents occurrence of hot water, sprinkling of hot water or jumping of hot water.
-Even if there is a variation in the amount of hot water supplied to the molten metal, it is possible to suppress the generation of surge pressure and prevent the occurrence of burrs, hot water spray, or jumping of the hot water tip.
The step-up piston accumulator and the control valves around it, which were necessary separately from the injection piston accumulator 20 that was necessary in the past, can be deleted.
・ By eliminating the need for components and valves, it is possible to improve the complicated control method and reduce the cost of the apparatus.

  With the die casting machine of the second embodiment of the present invention, the same effect as that of the first embodiment can be expected.

  In the hydraulic circuit of the embodiment described above or shown in the attached drawings, for the sake of easy understanding, only the minimum components are basically described, but the function, control, and arrangement of the device are described. Components such as a valve, a strainer, and a sensor that are necessary depending on the above may be added.

  In the above embodiment, the material of casting (molten metal) is described as aluminum, but other materials may be used.

  The numerical values described in this specification and, for example, FIGS. 3 and 4 are used for convenience of explanation, and the present invention is not particularly limited by these numerical values. For example, the type of the die casting machine is changed. These numbers can change.

  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 applied to the hydraulic circuit of an injection device in a die casting machine for casting aluminum products, and can contribute to improving product quality and improving productivity.

DESCRIPTION OF SYMBOLS 1 Plunger tip 2 Plunger rod 3 Injection coupling 4 Piston rod 5 Piston head 6 Cylinder 16H Head chamber 16R Rod chamber 7 Plunger sleeve 8 Fixed mold 9 Movable mold 10 Fixed platen 11 Movable platen 12 Cavity (cavity)
13 piston 15 (aluminum) molten metal 20 injection piston accumulator 21 outlet switching valve 26 injection switching valve 31 high speed speed adjustment valve 40 tank 80 gas bottle 82 filling force pattern adjustment valve 100 die casting machine 101 mold 102 injection cylinder 211 piston 217 gas Chamber 218 Hydraulic oil chamber 303 Hydraulic device 403 Hydraulic device

Claims (5)

A mold (101) for casting a product;
An injection cylinder (102) for injecting molten metal (15) to the mold (101) by moving a piston (13) provided by itself, and when hydraulic fluid is supplied thereby, When the piston (13) is advanced toward the mold (101), the head chamber (16H) and hydraulic oil are supplied, thereby moving the piston (13) away from the mold (101). An injection cylinder (102) comprising a rod chamber (16R), retracted to
Hydraulic devices (303, 403) for supplying hydraulic oil to the injection cylinder (102);
In a die casting machine (100) comprising:
The hydraulic device (303, 403)
An injection piston accumulator (20) that supplies hydraulic oil that presses the piston (13) of the injection cylinder (102) to the injection cylinder (102), and a hydraulic oil chamber (218) that stores the hydraulic oil; An injection piston accumulator (20) formed inside by gas-tightly partitioning a gas chamber (217) containing gas by the piston (211) of the injection piston accumulator (20);
The piston of the injection piston accumulator (20) is installed in fluid communication with the gas chamber (217) of the injection piston accumulator (20) and supplies gas to the gas chamber (217). A gas bottle (80) for driving hydraulic oil by pressing 211);
A filling force pattern adjusting valve (82) disposed between the gas chamber (217) of the injection piston accumulator (20) and the gas bottle (80) to adjust the flow of gas;
A high speed speed adjusting valve (31) for controlling the injection speed of the piston (13) of the injection cylinder (102);
A pressure detector (50) for detecting the pressure in the hydraulic oil chamber (218) of the injection piston accumulator (20);
It has
The filling force pattern adjustment valve (82) is a servo motor valve whose opening degree is variable and can be set, and the filling force pattern adjustment valve (82) is opened by the pressure detected by the pressure detector (50). A die-casting machine characterized in that the filling force of hydraulic oil into the injection cylinder (102) can be adjusted by feedback control of the degree. The hydraulic device (303, 403) further includes an injection speed detector for detecting the speed of the piston (13) of the injection cylinder (102) in order to detect the injection speed of the molten metal (15),
The die-casting machine according to claim 1, wherein the high-speed speed adjusting valve (31) can be feedback-controlled by the injection speed to adjust the opening degree of the high-speed speed adjusting valve (31).   The high-speed speed adjusting valve (31) is disposed on either the inlet side of the head chamber (16H) of the injection cylinder (102) or the outlet side of the rod chamber (16H) of the injection cylinder (102). The die casting machine according to claim 1 or 2, wherein the die casting machine is used. A die casting method using the die casting machine (100) according to claim 1,
A low speed injection step of pressing the molten metal (15) in the injection cylinder (102) at a low speed;
A high-speed injection stage in which the molten metal (15) in the injection cylinder (102) is pressed at a high speed and injected into the mold (101);
Pressurizing the molten metal (15) in the mold (101) to a predetermined pressure;
Holding a pressure of the molten metal (15) pressurized in the pressurizing stage,
In a die casting method comprising:
In the pressurization step, the opening degree of the filling force pattern adjustment valve (82) is determined by using the pressure detected by the pressure detector (50) as a feedback signal, and a preset hydraulic oil pressure increase pattern and final pressure. The die casting method is characterized in that feedback control is performed so as to comply with the above. The hydraulic device (303, 403) further includes an injection speed detector for detecting the speed of the piston (13) of the injection cylinder (102) in order to detect the injection speed of the molten metal (15),
The opening degree of the high-speed speed adjustment valve (31) is feedback-controlled so that the injection speed becomes a predetermined value in each of the low-speed injection stage and the high-speed injection stage. The die-casting method described.

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