JP3713416B2 - Die casting machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a die casting apparatus, and particularly relates to an apparatus having a short filling time.
[0002]
[Prior art]
FIG. 6 is a principal hydraulic system diagram of a hydraulic circuit in a conventional die casting machine.
[0003]
Reference numeral (51) denotes an injection cylinder of a die casting machine, and an injection plunger (not shown in FIG. 6 ) is attached to the injection rod (52).
[0004]
FIG. 7 is a view showing a peripheral portion of the injection plunger (71). The injection plunger (71) attached to the injection rod (52) pushes the molten metal (80) supplied from the oil supply nozzle (72) to the hot water supply sleeve (73) to the mold side by moving forward (injection). The molten metal (80) is filled in the cavity (74).
[0005]
The injection cylinder (51) is operated by an injection accumulator (53) serving as a pressure oil source. The pressure oil supplied from the injection accumulator (53) flows into the high speed speed adjustment valve (55) through the low speed injection check valve (59) and the low speed speed adjustment valve (60) or the high speed injection check valve (58).
[0006]
The opening speed of the high-speed speed adjustment valve (55) can be adjusted, thereby adjusting the maximum flow rate of oil flowing into the head chamber of the injection cylinder (51) and adjusting the speed when the injection rod (52) moves at high speed. can do.
[0007]
When the injection process is started and the injection rod (52) moves forward, the return oil pushed out from the rod chamber of the injection cylinder (51) is returned to the tank (68 through the return oil pipe (67) and the high speed deceleration combined valve (66). ).
[0008]
Immediately before the injection is completed, the speed of the injection rod (52) is reduced. When the injection is completed, the pressure increase check valve (56) is turned ON, and the pressure increase cylinder (57) is moved by the hydraulic pressure of the injection accumulator (53) to press the head side of the injection rod (52). Thereby, the fine shape of the cavity (74) can be accurately transferred to the molten metal.
[0009]
The switching timing of the switching valve at each stage is controlled by detecting the position of the injection rod (52) with the switching member (61) interlocked with the injection rod (52) and the plurality of limit switches (62) to (65). ing.
[0010]
Incidentally, in recent years, die casting of Mg (magnesium) has become widespread, and the thickness of the molded product has been reduced. Since it is thin, the amount of molten metal used at one time is small and the molten metal is easy to cool. Therefore, it is required to shorten the filling time of the molten metal into the mold, and the filling speed is increased.
[0011]
However, when the speed is increased, the high-speed filling surge increases. Then, the cavity is pushed and widened by the high-speed filling surge, and the molten metal enters the gap, and it becomes easy to cause burrs in the molded product.
[0012]
Therefore, the injection plunger is decelerated at a stage before high-speed filling is completed in order to prevent high-speed filling surge.
[0013]
The deceleration is performed by tightening the high speed deceleration composite valve (66) provided in the return oil pipe (67). That is, the injection rod (52) is rapidly decelerated by tightening the high speed deceleration composite valve (66) and increasing the pressure on the rod side of the injection cylinder (51).
[0014]
However, if the pressure on the rod side of the injection cylinder (51) is suddenly increased and decelerated rapidly, a large surge pressure is generated on the rod side, and the rod side packing of the injection cylinder (51) and the high-speed deceleration compound valve (66) Is subject to a large surge pressure. Therefore, there is a problem that the packing and the high speed deceleration composite valve (66) are easily damaged.
[0015]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a die casting machine capable of rapidly decelerating an injection plunger while suppressing a surge pressure generated on the rod side of the injection cylinder.
[0016]
[Means for Solving the Problems]
The die casting machine according to claim 1 of the present invention includes an injection cylinder (1) for injecting a molten metal (80) into a cavity (74) of a mold , and an injection accumulator (3) serving as a hydraulic source of the injection cylinder (1 ). When, the head side of the injection cylinder (1) (1a) and the exit accumulator (3) and a differential pressure type check valve disposed in the conduit between the (5), from the rod side of the injection cylinder (1) (1b) Rod side flow rate adjusting means (16) for controlling the flow rate of the extruded oil, decompression start position detecting means (34) for detecting the decompression start position of the injection cylinder (1) , and from the decompression start position to the mold side And a deceleration start position detecting means (35) for detecting a deceleration start position , and the differential pressure type check valve (5) is a switching valve (13) when the pressure reduction start position detecting means (34) is turned on. The rod side flow rate adjusting means (16) is turned on by the deceleration start position detecting means. In this case, the flow rate of the oil pushed out from the rod side by the switching valve (18) is controlled to be reduced.
[0020]
According to this, when the pressure reduction start position is reached, the switching valve (13) is turned on and the flow rate of the differential pressure check valve (5) is reduced. Thereby, the hydraulic pressure on the head side (1a) of the injection cylinder (1) is reduced.
[0021]
Next, when the deceleration start position is reached, the switching valve (18) is turned ON, and the flow rate of the rod side flow rate adjusting means (16) is reduced. As a result, the oil pressure on the rod side (1b) of the injection cylinder (1) suddenly increases, and the injection rod (2) decelerates rapidly.
[0022]
Even if the injection rod (2) is decelerated rapidly, the hydraulic pressure on the head side (1a) of the injection cylinder (1) has already been reduced, so that no large surge pressure is generated on the rod side. Therefore, it is possible to prevent an impact caused by a large surge pressure on the rod side packing and the flow rate control means.
[0023]
The invention described in claim 2 and claim 3 limits the means for increasing the filling pressure of the injection cylinder (1) in claim 1 . That is, claim the 2, wherein the die casting machine, have rows by pressure increase accumulator (4) increasing the pressure of the pressure increasing the head (1a) side of the filling pressure of the injection cylinder (1), according to claim 3, wherein the die casting machine In this case, the pressure increasing cylinder (9) provided on the head side of the injection cylinder (1 ) is operated .
[0027]
A die casting machine according to a fourth aspect of the present invention is the die casting machine according to any one of the first to third aspects, wherein the rod side flow rate adjusting means (16) is a servo valve.
[0028]
According to this, each low-speed, high-speed, and deceleration flow rate adjustment on the rod side can be performed by one servo valve (electromagnetic proportional flow control valve).
[0029]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to preferred embodiments.
[0030]
[Example 1]
FIG. 1 is a diagram showing a hydraulic system diagram of a main part of a hydraulic circuit in the die casting machine of this embodiment. For ease of explanation, the hydraulic circuit when the rod is retracted is omitted in the drawing.
[0031]
(1) is an injection cylinder of a die casting machine, and an injection plunger (see FIG. 7) is mounted on the injection rod (2).
[0032]
The injection accumulator (3), which is a pressure oil source, advances the injection plunger and injects and fills the mold cavity with a molten metal such as aluminum or magnesium. When the injection is almost complete, the pressure increase check valve (8) is `` ON '' Thus, the hydraulic pressure from the injection accumulator (3) is sent to the pressure- increasing cylinder (7) provided on the head side of the injection cylinder (1) and enters the pressure-increasing step as in the conventional case.
[0033]
Many of the configurations are substantially the same as the conventional example of FIG. 7 described above, but in addition to the differential pressure check valve (5), the pipe connected to the differential pressure check valve (5), the switching valve (13), and the conventional limit switch, The difference is that a limit switch (34) for detecting the timing of pressure reduction is provided between the start of deceleration and the start of deceleration.
[0034]
In the figure, (5) is a differential pressure check valve, and at the time of injection, the pressure oil from the injection accumulator (3) is appropriately adjusted to flow into the head chamber (1a) of the injection cylinder (1), and the injection rod ( Has the function of moving 2) forward. In this embodiment, a differential pressure check valve described in JP-A-1-150457 was used.
[0035]
FIG. 2 is a sectional view of the differential pressure check valve (5). The valve body (6) is accommodated in the valve box (5a). Pressure oil from the injection accumulator (3) flows into the inflow side chamber (7b) in the valve box (5a) from the pipe line (14a).
[0036]
Then, the hydraulic pressure in the inflow side chamber (7b) increases, and the valve body (6) is pressed by the oil in the inflow side chamber (7b) and resists the spring (5a). Move to 5b) side).
[0037]
As a result, the inflow side chamber (7b) and the outflow side chamber (7c) partitioned by the valve body (6) communicate with each other, and the oil passes between the valve box (5a) and the valve body (6) to reach the outflow side chamber. Enters (7c), flows out from the pipe (14b), and is sent to the head chamber (1a) of the cylinder (1).
[0038]
Therefore, the size of the flow path between the inflow side chamber (7b) and the outflow side chamber (7c) formed in the gap between the valve box (5a) and the valve body (6) is reduced to the head chamber (1a). The oil flow rate will be determined.
[0039]
(5b) is an opening degree adjusting unit capable of adjusting the movable range of the valve element (6) in the valve box (5a), and determines the maximum oil flow rate through the differential pressure check valve (5). Thereby, it can adjust so that it may become a suitable maximum injection speed according to the magnitude | size of the cavity of a metal mold | die, etc.
[0040]
However, the oil pressure flowing in from the pipe line (14a) alone cannot move the valve element (6) to the maximum against the spring (5c) to secure the flow path. The oil flow rate through (5) is small.
[0041]
(7a) is a cylinder chamber provided between the piston part (6a) of the valve body (6) and the end part of the valve box (5a), to which a pipe line (14c) is connected. The pipe (14c) is connected to the injection accumulator (3) via the switching valve (13).
[0042]
When hydraulic pressure from the injection accumulator (3) is applied to the cylinder chamber (7a), the valve body (6) is strongly pressed toward the opening adjustment section (5b), and the inflow side chamber (7b) and the outflow side chamber (7c) A large flow path can be secured. Therefore, the flow rate of oil passing through the differential pressure check valve (5) can be increased.
[0043]
In addition, (7e) is a small hole that communicates the opening adjustment unit side oil chamber (7d) and the outflow side chamber (7c), increasing the oil pressure of the opening adjustment unit side oil chamber (7d) at the time of oil backflow, It has a function of moving the valve body (6) to the left side in the figure. As a result, the flow path between the inflow side chamber (7b) and the outflow side chamber (7c) is closed during reverse flow.
[0044]
(31) is a switching member that interlocks with the injection rod (2). The position of the injection rod (2) comes into contact with various limit switches (32), (33), (34), (35), (36). Used to detect.
[0045]
[Description of operation (injection start-at low speed)]
Oil from the injection accumulator (3) flows into the differential pressure check valve (5) through the low-speed injection check valve (12) and the low-speed speed adjustment valve (11).
[0046]
The low speed control valve (11) has a function of controlling the oil flow rate at the time of low speed injection, and is adjusted in advance according to the conditions such as the cavity shape of the molded product. Therefore, it is not necessary to readjust in principle when the same molded article is continuously molded.
[0047]
At this time, the high-speed injection check valve (10) provided in parallel with the low-speed injection check valve (12) is closed, and almost no oil flows into the differential pressure check valve (5) via this.
[0048]
Oil from the injection accumulator (3) branches at a position upstream from the low-speed speed adjustment valve (11), passes through the switching valve (13) and the conduit (14c), and the cylinder chamber (7a )to go into.
[0049]
Then, pressure is applied to the cylinder chamber (7a) to press the valve body (6) (to the right in the drawing) so that the flow path in the differential pressure check valve (5) is expanded. Therefore, the oil flowing into the differential pressure check valve (5) flows into the head chamber (1a) of the injection cylinder (1) with a small resistance.
[0050]
When hydraulic pressure is applied to the head chamber (1a), the injection rod (2) moves forward, and the return oil pushed out from the rod chamber (1b) of the injection cylinder (1) is returned to the return oil line (15), the high-speed deceleration compound valve ( Return to tank (20) via 16).
[0051]
The high speed deceleration composite valve (16) includes a flow control valve element (16a) and a deceleration valve element (16b) provided on the back of the flow control valve element (16a).
[0052]
A speed control switching valve (17) is connected to the oil chamber behind the flow control valve element (16a). A switching valve (18) for deceleration is connected to the oil chamber behind the deceleration valve body (16b).
[0053]
FIG. 3 shows the movements of the switching valves (17) and (18) and the high speed deceleration combined valve (16) when the injection rod is stopped or when moving at a low speed immediately after the start of movement.
[0054]
Switching valve (17) is a state of "OFF", a rear side of the oil pressure flow control valve member from the injection accumulator (3) (16a), in front of the oil chamber of the reduction valve body (16b) Take it.
[0055]
On the other hand, the switching valve (18) is in the “OFF” state and is not connected to the hydraulic pressure source, so that no hydraulic pressure is applied to the rear of the deceleration valve body (16b).
[0056]
As a result, the flow rate control valve element (16a) is pressed to the right in the drawing, so that the flow path between the return oil pipe (15) and the tank (20) becomes narrow, and the flow rate is reduced.
[0057]
The deceleration valve element (16b) moves rearward (left side in the figure) by hydraulic pressure from the front.
[0058]
[Description of operation (at high speed)]
When the tip of the injection plunger advances and reaches the molten metal supply port of the plunger sleeve, the switching member (31) interlocked with the injection rod (2) presses the high-speed switching limit switch (33).
[0059]
Then, the hydraulic pressure in the pilot line of the high speed injection check valve (10) becomes zero, and the oil from the injection accumulator (3) flows into the differential pressure check valve (5) through the high speed injection check valve (10). Therefore, oil that has passed through the low-speed injection check valve (12) and oil that has passed through the high-speed injection check valve (10) flow into the differential pressure check valve (5).
[0060]
Since the amount of oil inflow per unit time into the differential pressure check valve (5) increases, the amount of oil per unit time flowing into the head chamber (1a) of the injection cylinder (1) also increases. The injection rod (2) moves in the cavity direction (left direction in the figure) at high speed, and the injection plunger attached to the tip of the injection rod (2) advances at high speed to inject the molten metal into the mold cavity.
[0061]
When the high speed switching limit switch (33) is turned on, the switching valve (17) connected to the high speed deceleration composite valve (16) is turned on. The oil chamber behind the flow control valve body (16a) is disconnected from the injection accumulator (3) and connected to the tank (20). FIG. 4 is a diagram showing the state of the high speed deceleration composite valve (16) and the switching valve (17) during the high speed injection.
[0062]
The flow rate control valve element (16a) loses hydraulic pressure to support the rear, and is pushed back by the oil from the return oil pipe (15). Therefore, the flow path between the return oil pipe (15) and the tank (20) becomes wider, and the return oil pushed out from the rod chamber (1b) of the injection cylinder (1) is returned to the tank (20) with little resistance. It is.
[0063]
The switching valve (18) remains “OFF”.
[0064]
[Description of operation (decompression start)]
When the tip of the injection plunger further advances to a point just before the completion of filling, the switching member (31) pushes the pressure reducing start change limit switch (34).
[0065]
As a result, the switching valve (13) provided between the injection accumulator (3) and the cylinder chamber (7a) of the differential pressure check valve (5) is turned “ON”. Then, the cylinder chamber (7a) of the differential pressure check valve (5) is disconnected from the injection accumulator (3) and connected to the tank (20).
[0066]
As a result, the hydraulic pressure in the cylinder chamber (7a) of the differential pressure check valve (5) is released, the valve body (6) moves to the left in the figure, and the flow path in the differential pressure check valve (5) becomes narrow. Since the amount of oil per unit time flowing into the head chamber (1a) of the injection cylinder (1) through the differential pressure check valve (5) decreases, the hydraulic pressure in the head chamber (1a) decreases.
[0067]
[Description of operation (deceleration start)]
When the tip of the injection plunger further advances, the switching member (31) pushes the deceleration start change limit switch (35).
[0068]
Then, the switching valve (18) is turned ON, the oil chamber located behind the deceleration valve body (16b) of the high speed deceleration composite valve (16) is connected to the injection accumulator (3), and the deceleration valve body ( Hydraulic pressure is applied behind 16b). FIG. 5 is a view showing the state of the high speed deceleration composite valve (16) and the switching valve (18) at this time.
[0069]
The area of the deceleration valve element (16b) is larger than the area of the flow control valve element (16a), and a large hydraulic pressure is applied. The deceleration valve body (16b) moves to the flow control valve body (16a) side, presses the flow control valve body (16a) from the rear, and the flow path between the return oil pipe (15) and the tank (20) Suddenly narrows. Therefore, the injection rod (2) is suddenly decelerated.
[0070]
However, since the hydraulic pressure on the head side that pushes out the injection rod (2) at the previous pressure reduction stage is reduced, the surge pressure generated on the rod side is small even if the injection rod (2) is suddenly decelerated.
[0071]
Therefore, the problem that the rod side packing of the injection cylinder (1) and the high speed deceleration composite valve (16) are damaged by a large surge pressure hardly occurs.
[0072]
[Description of operation (start of pressure increase)]
When the tip of the injection plunger further advances and reaches the position where the filling is completed, the switching member (31) presses the pressure increase switching limit switch (36) to enter the pressure increasing process.
[0073]
Then, the pressure increase check valve (8) is turned “ON”, and the hydraulic pressure by the injection accumulator (3) is sent to the pressure increase cylinder (7) provided on the head side of the injection cylinder (1).
[0074]
The pressure increasing cylinder (7) receiving the hydraulic pressure presses the injection rod (2) of the injection cylinder (1) toward the cavity side with a strong force. By this pressure increase, a high pressure is applied to the molten metal filled in the cavity, and the fine shape of the cavity can be accurately transferred to the molten metal. This state is maintained until the molten metal in the cavity is cooled and hardened.
[0075]
In addition, when high stability is required for the pressure increase, a dedicated hydraulic power source may be provided as a hydraulic pressure source for the pressure increasing cylinder (7) in addition to the injection accumulator (3).
[0076]
Retracting the [Operation (skip back cylinder) increase requires cooling in pressure state, each switch valve resetting, the injection rod over hydraulic pressure to the rod side and a retract valve (not shown) to "ON" (2) Let
[0077]
The reverse position is detected by the return limit switch (32), and the injection rod (2) is stopped at a predetermined position. Thereby, one molding is completed.
[0078]
[Example 2]
FIG. 8 is a main part hydraulic system diagram of the hydraulic circuit according to the second embodiment. In Example 1, the pressure increase was performed using a pressure increasing cylinder, but in this example, a pressure increasing accumulator (4) was separately used.
[0079]
When the pressure increase check valve (8) is turned “ON”, high pressure oil from the pressure increase accumulator (4) is sent to the head side of the injection cylinder (1). Generally, the pressure of the pressure increasing accumulator (4) is set to about twice the pressure of the injection accumulator (3).
[0080]
Since the differential pressure check valve (5) also functions as a check valve, the high pressure of the pressure increasing accumulator (4) is not applied to the injection accumulator (3).
[0081]
Other configurations and effects are the same as those of the first embodiment.
[0082]
[Example 3] (not shown)
In the first embodiment, the cylinder side flow rate restriction is performed by a high-speed deceleration composite valve, but in this embodiment, an electromagnetic proportional flow control valve (servo valve) is used instead.
[0083]
The flow rate of oil flowing out from the return oil pipe (15) to the tank (20) was adjusted by an electric signal based on the signal from the limit switch.
[0084]
The low-speed, high-speed, and deceleration flow rates on the rod side can be adjusted with a single servo valve (electromagnetic proportional flow control valve), and piping can be simplified.
[0085]
Other configurations and effects are the same as those of the first embodiment.
[0086]
In each of the above embodiments, the deceleration is started after the pressure reduction is started. However, even if the pressure reduction and the deceleration are performed simultaneously, the surge pressure generated on the rod side can be reduced to a certain extent.
[0087]
However, starting deceleration before pressure reduction is not appropriate because a large surge pressure is generated on the rod side as in the conventional case.
[0088]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a die casting machine capable of rapidly decelerating the injection plunger while suppressing the surge pressure generated on the rod side of the injection cylinder.
[Brief description of the drawings]
FIG. 1 is a main part hydraulic system diagram of a hydraulic circuit according to a first embodiment;
FIG. 2 is a cross-sectional view of a differential pressure check valve used in the present invention.
FIG. 3 is a diagram showing a state of a high-speed deceleration composite valve and a switching valve (when stopped, at low speed).
FIG. 4 is a diagram showing a state of a high speed deceleration composite valve and a switching valve (at high speed).
FIG. 5 is a diagram showing the states of a high speed deceleration composite valve and a switching valve (when decelerating).
FIG. 6 is a main part hydraulic system diagram showing a hydraulic circuit in a conventional die casting machine.
FIG. 7 is a view showing a peripheral portion of an injection plunger.
FIG. 8 is a principal hydraulic system diagram of a hydraulic circuit according to a second embodiment.
[Explanation of symbols]
(1) Injection cylinder
(1a) Head room
(1b) Rod chamber
(2) Injection rod
(3) Injection accumulator
(4) Booster accumulator
(5) Differential pressure check valve
(5a) Valve box
(5b) Opening adjustment section
(6) Disc
(6a) Piston part
(7a) Cylinder chamber
(7b) Inflow side chamber
(7c) Outflow side chamber
(8) Booster check valve
(9) Booster cylinder
(10) High speed injection check valve
(11) Low speed control valve
(12) Low speed injection check valve
(13) Switching valve (for pressure reduction)
(14a) Pipe line (outflow to differential pressure check valve)
(14b) Pipe line (outflow from differential pressure check valve)
(15) Return oil pipeline
(16) High-speed deceleration compound valve
(16a) Flow control valve
(16b) Deceleration valve body
(17) Switching valve (for high speed)
(18) Switching valve (for deceleration)
(20) Tank
(31) Switching member
(32) Return limit switch
(33) Fast switching limit switch
(34) Decompression start changeover limit switch
(35) Deceleration start changeover limit switch
(36) Pressure increase switching limit switch

Claims (4)

An injection cylinder for injecting molten metal into the cavity of the mold, an injection accumulator serving as a hydraulic pressure source of the injection cylinder,
A differential pressure check valve provided in a pipe line between the head side of the injection cylinder and the injection accumulator;
Rod-side flow rate adjusting means for controlling the flow rate of oil pushed out from the rod side of the injection cylinder;
Decompression start position detecting means for detecting the decompression start position of the injection cylinder;
A deceleration start position detecting means for detecting a deceleration start position located on the mold side from the decompression start position;
The differential pressure type check valve is controlled so as to reduce the flow rate by the switching valve when the pressure reducing start position detecting means is turned ON,
The rod-side flow rate adjusting means is controlled to reduce the flow rate of oil pushed out from the rod side by a switching valve when the deceleration start position detecting means is turned on . The pressure increase accumulator, die casting machine according to claim 1 in which the molten metal is characterized in that to increase the charging pressure of the injection cylinder after filling the cavity. 2. The die casting machine according to claim 1 , wherein the pressure increasing cylinder provided on the head side of the injection cylinder increases the filling pressure of the injection cylinder after the molten metal is filled in the cavity . Rod-side flow rate adjustment means die casting machine according to any one of claims 1 to 3, characterized in that a servo valve.

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