JP2011140059A - Hydraulic apparatus of molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic apparatus of a molding machine, which can detect abnormality of a hydraulic circuit with less burden. <P>SOLUTION: The hydraulic apparatus 14 of a die casting machine 1 includes: a pump 19; a hydraulic cylinder 13 by which hydraulic fluid is supplied from the pump 19 through a hydraulic circuit 16; a pressure sensor 26 for detecting the pressure of the hydraulic circuit 16; and a controller 17 that, in a molding cycle, controls the pump 19 and the hydraulic circuit 16 so that the hydraulic cylinder 13 is driven by the discharge of the hydraulic fluid of a prescribed driving feed quantity (F<SB>1</SB>) from the pump 19. The controller 17 controls the pump 19 so that the hydraulic fluid of a prescribed diagnostic feed quantity Ft which is more than a rated outside leak quantity F<SB>0</SB>of the hydraulic fluid in the hydraulic circuit 16 and less than the driving feed quantity (F<SB>1</SB>) can be discharged from the pump 19, and performs processing to report occurrence of the abnormality when the detected pressure of the pressure sensor 26 at that time is less than a prescribed reference pressure P<SB>0</SB>. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hydraulic apparatus used in a molding machine such as a die casting machine.

  2. Description of the Related Art A hydraulic device for a molding machine that can detect abnormality of a pump or a hydraulic circuit is known. The hydraulic device of the molding machine of Patent Document 1 includes a plurality of pumps, a hydraulic circuit to which hydraulic oil is supplied from the plurality of pumps, a hydraulic motor to which hydraulic fluid is supplied from the plurality of pumps via the hydraulic circuit, It has a pressure sensor that detects the discharge pressure of the pump and a tachometer that detects the rotation of the hydraulic motor.

  Then, this hydraulic device rotates a plurality of pumps at a predetermined rotational speed (rotational speed), and when the rotational speed of the hydraulic motor at that time deviates from the set rotational speed (when an abnormality occurs), Whether the abnormality has occurred in the pump or the hydraulic circuit is determined depending on whether or not the detected pressure of the pressure sensor is out of the predetermined value.

Japanese Utility Model Publication No. 62-94815

  In the technique of Patent Document 1, it is necessary to drive an actuator such as a hydraulic motor in order to detect an abnormality. Further, when detecting an abnormality, the member connected to the actuator is also driven. Furthermore, it is necessary to supply a large amount of hydraulic oil to the hydraulic circuit in order to drive the actuator, which consumes a lot of energy. As described above, the operation for detecting the abnormality of the hydraulic circuit becomes large, and the abnormality cannot be easily detected.

  An object of the present invention is to provide a hydraulic apparatus for a molding machine that can detect an abnormality of a hydraulic circuit with a small burden.

  The hydraulic device for a molding machine of the present invention includes a pump, a hydraulic circuit to which hydraulic fluid is supplied from the pump, a hydraulic cylinder to which hydraulic fluid is supplied from the pump via the hydraulic circuit, A pressure sensor that detects the pressure of the hydraulic circuit, and the pump and the liquid so that the hydraulic cylinder is driven by discharging a predetermined amount of hydraulic fluid from the pump in a molding cycle. A control device that controls a pressure circuit, wherein the control device has a predetermined diagnostic supply amount that is greater than the rated external leakage amount of the hydraulic fluid in the hydraulic circuit and less than the drive supply amount. The pump is controlled so that hydraulic fluid is discharged from the pump, and when the detected pressure of the pressure sensor at that time is less than a predetermined reference pressure, a process for notifying that an abnormality has occurred is performed.

  Preferably, the hydraulic device further includes a pump flow sensor for detecting a drain amount of the pump, and the control device controls the pump to be driven at a predetermined rotation speed and a predetermined capacity. When the detected pressure at that time is less than the reference pressure and the detected flow rate of the pump flow sensor is less than a predetermined reference pump drain amount, an abnormality has occurred in the hydraulic circuit. A process of notifying is performed, and when the detected flow rate of the pump flow sensor is equal to or greater than the reference pump drain amount, a process of notifying that an abnormality has occurred in the pump is performed.

  Preferably, the hydraulic circuit has a plurality of control valves, and is provided with a plurality of valve flow sensors for detecting drain amounts of the plurality of control valves, and the control device is configured to supply the diagnostic supply amount. In the case where the detected pressure when the pump is controlled so that the hydraulic fluid is discharged is less than the reference pressure, the valve flow sensor corresponding to the control valve in any of the plurality of control valves When the detected flow rate exceeds a predetermined reference valve drain amount set for each of the plurality of control valves, processing for notifying that an abnormality has occurred in the control valve is performed.

  Preferably, the hydraulic circuit has a plurality of valve groups including a valve group having a plurality of control valves and a valve group having at least one control valve, and detects a drain amount of the plurality of valve groups. A plurality of valve flow sensors are provided, and the control device controls the pump so that the diagnostic supply amount of hydraulic fluid is discharged, and the detected pressure is less than the reference pressure. In any of the plurality of valve groups, when the detected flow rate of the plurality of valve flow sensors corresponding to the valve group exceeds a predetermined reference valve drain amount set for each of the plurality of valve groups Then, a process for notifying that an abnormality has occurred in the valve group is performed.

  Preferably, the control device holds a database in which the pressure and the number of molding cycles are associated with each other, and refers to the database so that the diagnostic supply amount of hydraulic fluid is discharged. The number of cycles corresponding to the detected pressure when the pump is controlled is specified, and information based on the difference between the specified number of cycles and a predetermined limit cycle number is notified.

  Preferably, the hydraulic device further includes a temperature sensor that detects a temperature of the hydraulic fluid, and the control device increases the supply amount for diagnosis in accordance with an increase in a temperature detected by the temperature sensor.

  ADVANTAGE OF THE INVENTION According to this invention, abnormality of the hydraulic circuit in the hydraulic apparatus of a molding machine can be detected with a small burden.

The figure which shows schematic structure of the die-casting machine which concerns on embodiment of this invention. The block diagram which paid its attention to the pump part which shows the structure of the hydraulic apparatus of the die-casting machine of FIG. The block diagram which paid its attention to the hydraulic circuit which shows the structure of the hydraulic apparatus of the die-casting machine of FIG. The figure explaining the abnormality diagnosis method in the hydraulic apparatus of FIG. The figure explaining the failure prediction method in the hydraulic apparatus of FIG. The figure explaining correction | amendment of the supply quantity of the hydraulic fluid to the hydraulic circuit at the time of abnormality diagnosis in the hydraulic apparatus of FIG. The flowchart which shows the procedure of the process of the abnormality diagnosis which the hydraulic device of FIG. 2 performs. The block diagram which paid its attention to the hydraulic circuit which shows the structure of the hydraulic apparatus which concerns on the modification of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, a code | symbol may attach the additional code | symbol of a capital letter like the "1st switching valve 31A, the 2nd switching valve 31B" etc. about the thing of the same or similar structure. Further, in this case, the number at the beginning of the name and / or the above additional code may be omitted, such as simply “the switching valve 31”.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a die casting machine 1 according to a first embodiment of the present invention.

  The die casting machine 1 injects a mold clamping apparatus 3 for opening and closing the mold 501, a spray apparatus 4 for applying a release agent or the like to the mold 501, and a molten metal (molten metal) as a molding material to the mold 501. And an extrusion device 6 for extruding a die-cast product as a molded product from the mold 501.

  The outline of the operation in the molding cycle of the die casting machine 1 is as follows.

  First, in the mold clamping device 3, the movable die plate 8 that holds the movable mold 505 approaches the fixed die plate 7 that holds the fixed mold 503, and the mold is closed and clamped. Next, in the injection device 5, the molten metal is supplied to the injection sleeve 9 communicating with the cavity Ca of the mold 501, and the injection plunger 10 slides in the injection sleeve 9, whereby the molten metal is injected and filled into the cavity Ca. The

  Thereafter, when a predetermined time elapses and the molten metal in the cavity Ca is solidified, in the mold clamping device 3, the movable die plate 8 is moved away from the fixed die plate 7, and the mold is opened. In parallel with the mold opening or after the mold opening, an unillustrated extrusion pin of the extrusion device 6 protrudes from the dividing surface of the moving mold 505, and the molded product is extruded from the moving mold 505.

  When the molded product is extruded, the spray device 4 inserts the nozzle portion 11 having a plurality of nozzles 11a between the fixed mold 503 and the movable mold 505, which are opened by a driving device (not shown), The mold release agent is ejected from the nozzle 11a to the mold 501. Then, the nozzle portion 11 is retracted from between the fixed mold 503 and the movable mold 505, and the preparation for the next molding cycle is completed.

  In order to realize such an operation, the die casting machine 1 has a hydraulic actuator. For example, the mold clamping device 3 includes a mold clamping cylinder 13 </ b> A that drives the movable die plate 8. The injection device 5 has an injection cylinder 13 </ b> B that drives the injection plunger 10. The extrusion apparatus 6 has an extrusion cylinder 13C that drives an unillustrated extrusion pin.

  In the following description, the mold clamping cylinder 13A, the injection cylinder 13B, and the extrusion cylinder 13C are referred to as “hydraulic cylinder 13” and may not be distinguished from each other.

  Although not particularly shown, these hydraulic cylinders 13 include a cylinder tube, a piston that can slide the cylinder tube, and a rod connected to the piston. The piston divides the inside of the cylinder tube into two cylinder chambers, and the hydraulic cylinder 13 is driven by supplying hydraulic fluid (for example, oil) selectively to the two cylinder chambers.

  FIG. 2 is a block diagram illustrating a configuration of the hydraulic device 14 of the die casting machine 1. However, FIG. 2 is a conceptual diagram, and shows a hydraulic system that is simplified or modified for convenience of explanation than the actual hydraulic system. The same applies to other block diagrams to be described later.

  The hydraulic device 14 includes a pump unit 15 that delivers hydraulic fluid, and a hydraulic circuit 16 that controls the flow of hydraulic fluid between the pump unit 15 and the hydraulic cylinder 13. In addition, the hydraulic device 14 has a control device 17 for controlling the operation of the pump unit 15 and the hydraulic circuit 16 and determining the presence or absence of abnormality in these.

  The pump unit 15 includes a pump 19, an electric motor 20 that drives the pump 19, and an encoder 21 that detects the rotation of the electric motor 20.

  The pump 19 is constituted by a variable displacement pump capable of changing the discharge amount in one cycle of the pump 19, for example. The pump 19 may be a rotary type such as a gear pump or a vane pump, or may be a plunger type such as an axial plunger pump or a radial plunger pump.

  The pump 19 sucks the hydraulic fluid stored in the tank 23 from the suction port 19a and discharges it from the discharge port 19b by rotating a rotor (not shown) or reciprocating a piston (not shown). Although not particularly illustrated, in the pump 19, the working fluid from the suction port 19a is accommodated, and a chamber for pushing the working fluid to the discharge port 19b is formed by a casing and a rotor, or a casing and a piston. Yes.

  Further, in the pump 19, the hydraulic fluid flowing out from the chamber for extruding the hydraulic fluid through the gap between the casing and the rotor or the gap between the casing and the piston is transferred to the tank 23 via the drain port 19c. Returned.

  The electric motor 20 is constituted by, for example, a servo motor. That is, the servo driver 58 drives the electric motor 20 at a rotational speed corresponding to the command value by feedback control based on a comparison between the detection value of the encoder 21 and the command value (control signal) input as appropriate. The electric motor 20 may be a direct current motor or an alternating current motor.

  The encoder 21 outputs a number of pulses proportional to the rotational speed of the electric motor 20 to the control device 17. Therefore, the control device 17 can specify the rotation speed of the electric motor 20 (pump 19) by counting the number of pulses.

  The hydraulic fluid discharged from the discharge port 19 b of the pump 19 is supplied to the hydraulic circuit 16. In the flow path between the discharge port 19b and the hydraulic circuit 16, a relief valve 24 that limits the maximum pressure of the hydraulic fluid by discharging the hydraulic fluid to the tank when the hydraulic fluid pressure reaches a predetermined pressure. Is provided.

  In the flow path between the discharge port 19b and the hydraulic circuit 16, a temperature sensor 25 for detecting the temperature of the hydraulic fluid and a pressure sensor 26 for detecting the pressure of the hydraulic fluid are provided. Further, the pump unit 15 is provided with a pump flow sensor 27 for detecting the discharge amount (drain amount) of the hydraulic fluid from the drain port 19c.

  The temperature sensor 25 outputs a multi-value signal whose signal level (for example, voltage) varies according to the variation of the temperature of the hydraulic fluid to the control device 17. Similarly, the pressure sensor 26 outputs a multi-value signal whose signal level fluctuates according to the fluctuation of the pressure of the hydraulic fluid to the control device 17. The pump flow sensor 27 outputs a multi-value signal whose signal level varies according to the variation in the drain amount to the control device 17. The signal may be analog or digital. The same applies to other signals.

  The control device 17 includes a power supply circuit 51 that supplies power to each unit, a main control unit 52 that outputs a control signal to each unit, and a hydraulic device diagnosis circuit 53 that instructs the main control unit 52 to perform abnormality diagnosis. is doing.

  The power supply circuit 51 includes, for example, a transformer and converts power supplied from a commercial power supply into an appropriate voltage and supplies the converted voltage to each unit. A power OFF switch 55 and a power ON switch 56 are connected to the power supply circuit 51 in order to allow or block power supply from the commercial power supply to the power supply circuit 51.

  The main control unit 52 includes, for example, a CPU, a ROM, a RAM, and the like. The main control unit 52 outputs a control signal to the servo driver 58, the display unit 59, and the like based on a predetermined program, a user operation on the input unit 57, and the like.

  The main control unit 52 includes a comparison unit 61 that performs a predetermined comparison process based on detection values of various sensors, an abnormality determination circuit 62 that determines presence / absence of an abnormality based on a comparison result of the comparison unit 61, and a comparison unit 61 and a database 63 referred to by the abnormality determination circuit 62.

  A diagnosis ON switch 65 and a diagnosis ON circuit 67 are connected to the hydraulic equipment diagnosis circuit 53.

  The diagnosis ON switch 65 is operated at any time by the user, and outputs an ON signal to the hydraulic device diagnosis circuit 53 according to the operation. When an ON signal is input from the diagnosis ON switch 65, the hydraulic device diagnosis circuit 53 instructs the abnormality determination circuit 62 to perform diagnosis.

  The diagnosis ON circuit 67 outputs an ON signal to the hydraulic device diagnosis circuit 53 in the same manner as the diagnosis ON switch 65 when power is supplied to the power supply circuit 51 (when the die casting machine 1 is activated). The diagnosis ON circuit 67 can be set as to whether or not to give a diagnosis instruction at the time of activation by an operation on the input unit 57.

  FIG. 3 is another block diagram showing the configuration of the hydraulic system and the signal processing system of the hydraulic device 14. However, while FIG. 2 described above focuses on the configuration of the pump unit 15, FIG. 3 focuses on the configuration of the hydraulic circuit 16.

  The hydraulic circuit 16 has a plurality of control valves that control the flow of hydraulic fluid from the pump unit 15. For example, the hydraulic circuit 16 includes a plurality of switching valves 31, pressure reducing valves 32, and check valves 33.

  The plurality of switching valves 31 are connected to each other in parallel, for example. The pressure reducing valve 32 is connected in series to one port of the first switching valve 31A, for example. The check valve 33 is connected in series to one port of the second switching valve 31B, for example.

  For example, the first switching valve 31 </ b> A and the pressure reducing valve 32 control the flow of hydraulic fluid to one hydraulic cylinder 13. Similarly, the second switching valve 31 </ b> B and the check valve 33 control the flow of hydraulic fluid with respect to the other hydraulic cylinder 13. Thus, the hydraulic circuit 16 can control the flow of the hydraulic fluid individually with respect to the plurality of hydraulic cylinders 13 by having a plurality of control valves.

  The switching valve 31 is composed of, for example, a switching valve with 4 ports and 3 positions. The four ports are connected to two cylinder chambers, for example, a pump unit 15, a tank 23, and a hydraulic cylinder 13. The switching valve 31 is connected to the pump unit 15 (tank 23) and one (the other) cylinder chamber, and the pump unit 15 (tank 23) and the other (one) by switching the spool position between the three positions. ) Is connected to the cylinder chamber, and the pump unit 15 (tank 23) is disconnected from the two cylinder chambers. The switching valve 31 is constituted by, for example, an electromagnetic pilot valve in which a solenoid is driven by input of an electric signal, pilot pressure is introduced by driving of the solenoid, and a spool is driven by introduction of pilot pressure.

  The pressure reducing valve 32 is configured to keep the pressure on the first switching valve 31A side at a constant pressure. Further, the pressure reducing valve 32 is configured to be able to operate even when pilot pressure is introduced.

  The check valve 33 is configured to allow the flow of hydraulic fluid from the second switching valve 31B side and prevent the flow in the reverse direction. Further, the check valve 33 is configured to allow the flow to the second switching valve 31B side by introducing pilot pressure.

  The hydraulic device 14 has a plurality of valve flow sensors 35 that detect the flow rate (drain amount) of the hydraulic fluid from the drain ports of the plurality of control valves (31, 32, 33, etc.). The valve flow sensor 35 outputs a multi-value signal whose signal level fluctuates according to the fluctuation of the drain amount to the control device 17.

  The hydraulic device 14 has a hydraulic device control circuit 37 for controlling a plurality of control valves (31, 32, 33, etc.). The main control unit 52 outputs a control signal to the hydraulic device control circuit 37, and the hydraulic device control circuit 37 outputs electric power corresponding to the control signal to each control valve or the like.

  The display unit 59 includes, for example, a plurality of lamps that notify the presence / absence of an abnormality by turning on, blinking, or turning off. For example, the display unit 59 includes a pump lamp 69 (FIG. 2) for informing the presence / absence of abnormality of the pump unit 15 and a hydraulic circuit lamp 70 (FIG. 2) for informing the presence / absence of abnormality of the hydraulic circuit 16. 3) and a plurality of valve lamps 71 (FIG. 3) for informing the presence or absence of abnormality of the plurality of control valves (31, 32, 33, etc.). The display unit 59 includes a display for displaying an image, such as a liquid crystal display or an organic EL display, although not particularly illustrated.

  FIG. 4 is a diagram illustrating an abnormality diagnosis method in the hydraulic device 14.

  Specifically, FIG. 4 shows the change over time of the amount of hydraulic fluid supplied to the hydraulic circuit 16 (the amount discharged from the pump 19), the horizontal axis indicates time, and the vertical axis indicates the amount of hydraulic fluid supplied. ing. FIG. 4 is a schematic diagram and does not accurately represent the change in the amount of hydraulic fluid supplied to the hydraulic circuit 16.

  As the die casting machine 1 repeatedly performs the molding cycle with the period T, the change in the amount of hydraulic fluid supplied to the hydraulic circuit 16 also varies periodically with the period T. The change in the supply amount is caused by a change in the rotation speed or a change in the capacity of the pump 19.

  In each molding cycle, the supply amount increases when the hydraulic cylinder 13 is driven, and the supply amount decreases when the hydraulic cylinder 13 is not driven. When the hydraulic cylinder 13 is not driven, the pump 19 (the electric motor 20) may be stopped and the supply amount may be set to 0 even during the molding cycle.

In the hydraulic circuit 16, hydraulic fluid having an external leakage amount F ₀ leaks outside the hydraulic circuit 16 due to leakage of hydraulic fluid in a gap between components of a hydraulic device (such as a control valve). The external leak amount F ₀ is, for example, the sum of drain amounts of a plurality of control valves (31, 32, 33, etc.). To drive the hydraulic cylinder 13, it is necessary hydraulic fluid of more supply amount than the external leakage amount F ₀ is a certain difference is supplied to the hydraulic circuit 16. Accordingly, the maximum values F ₁ and F ₂ of the amount of hydraulic fluid supplied to the hydraulic circuit 16 are set to be larger than the external leak amount F ₀ with a certain difference.

In the following description, it is assumed that the maximum value F ₁ is the minimum maximum value related to the amount of hydraulic fluid supplied to the hydraulic circuit 16 when driving at least one hydraulic cylinder 13. The maximum values F ₁ and F ₂ can be maintained for a predetermined time as shown in FIG.

During diagnosis, more than the external leakage amount F _0, and, with fewer diagnostic supply amount Ft than the maximum value F _1, hydraulic fluid is supplied to the hydraulic circuit 16. At this time, the hydraulic circuit 16 (a plurality of control valves) is controlled so as to cut off the supply of hydraulic fluid to an actuator such as the hydraulic cylinder 13.

  On the other hand, the gap between the plurality of control valves (31, 32, 33, etc.) increases due to wear, and the amount of drain gradually increases. Further, even when a failure occurs unexpectedly, the leakage of the hydraulic fluid may increase.

  Accordingly, if the hydraulic circuit 16 is normal, the pressure of the hydraulic circuit 16 rises to a predetermined reference pressure. On the other hand, if the progress of wear exceeds a predetermined level, or a sudden failure occurs and the amount of hydraulic fluid leakage increases, the pressure of the hydraulic circuit 16 does not reach a predetermined reference pressure. Based on this, the presence or absence of abnormality of the hydraulic circuit 16 is determined.

  Further, in the present embodiment, the supply of the hydraulic fluid with the diagnostic supply amount Ft is realized by controlling the electric motor 20 and the pump 19 with the rotation speed and capacity set in advance corresponding to the diagnostic supply amount Ft. Is done. In other words, the supply amount of the hydraulic fluid supplied to the hydraulic circuit 16 is not detected and the supply amount is not feedback controlled.

  Accordingly, when an abnormality occurs in the pump unit 15, the hydraulic fluid of the diagnostic supply amount Ft is not supplied to the hydraulic circuit 16, and the pressure of the hydraulic circuit 16 does not reach the reference pressure. That is, the abnormality of the pump unit 15 is also detected by detecting the pressure of the hydraulic circuit 16.

  When the drain amount of the pump 19 detected by the pump flow sensor 27 exceeds a predetermined reference pump drain amount, it is possible to specify that the abnormal portion is the pump unit 15, and the drain amount is a predetermined reference pump. When the drain amount is not exceeded, it can be specified that the abnormal portion is the hydraulic circuit 16.

The external leak amount F ₀ is an external leak amount when the hydraulic circuit 16 exhibits the performance expected by the manufacturer and / or the worker (normal time), so to speak, it is the rated external leak amount. is there. As the rated external leak amount F ₀ , for example, those described in the specifications of the hydraulic device 14 can be used. The rated external leak amount F ₀ in the hydraulic circuit 16 is the rated external leak amount for each hydraulic device described in the specifications of the hydraulic device (control valve, etc.) constituting the hydraulic circuit 16. It may be obtained from the sum. Further, the external leakage amount measured in the hydraulic device 14 (the hydraulic device 14 immediately after shipment or the hydraulic device 14 in a state corresponding thereto) in which wear has not progressed may be set as the rated external leakage amount F _0. .

Diagnostic supply amount Ft is greater than the external leakage amount F ₀ rating, but it fewer than drive supply amount (F ₁₎ when driving the hydraulic cylinder, slightly external leakage amount F ₀ rating It is preferable to exceed the above range. For example, diagnostic supply amount Ft is preferably an amount exceeding the external leakage amount F ₀ rated by the difference of 10% to 50% of the amount of external leakage amount F ₀ rating.

  FIG. 5 is a diagram for explaining a failure prediction method in the hydraulic device 14.

  Specifically, FIG. 5 shows a long-term change over time in the pressure of the hydraulic circuit 16 at the time of the above-described abnormality diagnosis (when hydraulic fluid of the diagnostic supply amount Ft is supplied), and the horizontal axis indicates the execution. The number of molding cycles performed, the vertical axis indicates the pressure of the hydraulic circuit 16 at the time of abnormality diagnosis.

Even if a sudden failure does not occur in the hydraulic circuit 16, if the molding cycle is repeated, wear proceeds and the amount of external leakage increases. Therefore, the pressure of the hydraulic circuit 16 at the time of abnormality diagnosis gradually decreases as the molding cycle is repeated. Then, it is judged if the pressure falls below a predetermined reference pressure P _0, that an abnormality has occurred.

In the process in which such normal wear progresses, as illustrated in FIG. 5, there is a correlation between the number of cycles and the pressure of the hydraulic circuit 16 at the time of abnormality diagnosis. Therefore, by checking the correlation in advance, it is possible to predict the time when the pressure at the time of abnormality diagnosis is lower than the reference pressure P ₀ based on the current pressure at the time of abnormality diagnosis.

For example, it can be identified when the pressure at the time of the current abnormality diagnosis is assumed to be P _1, the correlation illustrated in FIG. 5, the number of cycles n ₁ corresponding to the pressure P _1. Then, from the difference between the limit cycle number n ₀ corresponding to the reference pressure P ₀ and the current cycle number n ₁ , the cycle number n ₂ (= n ₀ −n ₁ ) until the occurrence of abnormality can be calculated.

  FIG. 6 is a diagram for explaining the correction of the diagnostic supply amount Ft. The horizontal axis indicates the temperature, and the vertical axis indicates the diagnostic supply amount Ft.

  When the molding cycle is repeated, the temperature of the hydraulic fluid rises due to friction between the hydraulic fluid and the hydraulic equipment. In addition, the temperature of the hydraulic fluid is also affected by changes in the environment in which the die casting machine 1 is disposed and the environment (air temperature). When the temperature of the hydraulic fluid rises, the viscosity of the hydraulic fluid decreases and the amount of external leakage increases.

  Therefore, the die casting machine 1 corrects the diagnostic supply amount Ft based on the temperature of the hydraulic fluid. In other words, the die casting machine 1 sets the diagnostic supply amount Ft according to the temperature of the working fluid.

  For example, the database 63 holds a map in which the temperature and the diagnostic supply amount Ft are associated with each other. As shown in FIG. 6, the map is set so that the diagnostic supply amount Ft increases as the temperature of the hydraulic fluid increases. The abnormality determination circuit 62 refers to the database 63, specifies the diagnostic supply amount Ft corresponding to the temperature detected by the temperature sensor 25, and supplies the hydraulic fluid at the specified diagnostic supply amount Ft. To instruct. The map in which the pressure is associated with the correction amount of the diagnostic supply amount Ft is also a map in which the pressure is associated with the diagnostic supply amount Ft in a broad sense.

  In the present embodiment, as described above, the supply of the hydraulic fluid of the diagnostic supply amount Ft is performed by the electric motor 20 and the pump so that the rotation speed and capacity set in advance corresponding to the diagnostic supply amount Ft are maintained. This is realized by controlling 19. Therefore, the correction based on the temperature is actually performed at least one of the rotational speed and the capacity, and the database 63 holds a map in which the temperature is associated with at least one of the rotational speed and the capacity.

  FIG. 7 is a flowchart showing a procedure of abnormality diagnosis processing executed by the hydraulic device 14.

  As described above, this process is started by an operation on the diagnosis ON switch 65, or is started when a start instruction is given by the diagnosis ON circuit 67 when the die casting machine 1 is started.

  In step S <b> 1, the hydraulic device 14 starts control to supply the diagnostic supply amount Ft of hydraulic fluid to the hydraulic circuit 16. Specifically, as described with reference to FIG. 6, the main control unit 52 corrects at least one of the rotation speed and the capacity corresponding to the diagnostic supply amount Ft based on the temperature. The main control unit 52 controls the electric motor 20 and the pump 19 so that the corrected rotation speed and capacity are maintained.

  In step S2, the hydraulic device 14 waits until the electric motor 20 and the pump 19 are in a steady state and the pressure in the hydraulic circuit 16 is in a steady state. The standby may be performed until it is determined that a detection value of a predetermined sensor such as the pressure sensor 26 has reached a steady state, or may be performed until a predetermined time elapses.

  In step S <b> 3, the hydraulic device 14 acquires the pressure detected by the pressure sensor 26, that is, the pressure of the hydraulic circuit 16.

In step S4, the hydraulic device 14 determines whether or not the detected pressure obtained in step S3 is less than the reference pressure P _0. If it is determined that the detected pressure is not less than the reference pressure P ₀ , the process proceeds to step S5. If it is determined that the detected pressure is less than the reference pressure P ₀ , the process proceeds to step S8.

  In step S <b> 5, the hydraulic device 14 performs a process for notifying that no abnormality has occurred in the hydraulic device 14. For example, the main control unit 52 turns off the pump lamp 69, the hydraulic circuit lamp 70, and the plurality of valve lamps 71.

In step S6, the hydraulic device 14 performs the failure prediction described with reference to FIG. Specifically, the control device 17 holds the map shown in FIG. Then, the abnormality determination circuit 62 refers to the database 63 to identify the number of cycles n ₁ corresponding to the detected pressure detected by the pressure sensor 26, and the number of cycles n ₂ (= n ₀ −n until the occurrence of abnormality). ₁ ) is calculated.

In step S7, the hydraulic device 14 displays on the display section 59 the information based on the number of cycles n ₂ to the calculated abnormality occurs in step S6. The information based on the cycle number n ₂ is, for example, the failure time calculated by a predetermined calculation formula into which the cycle number n ₂ itself and the cycle number n ₂ are substituted.

  In step S8, it is determined whether or not the drain amount detected by the pump flow sensor 27 is less than a predetermined reference pump drain amount. If it is determined that the detected drain amount is not less than the reference pump drain amount, the process proceeds to step S9. If it is determined that the detected drain amount is less than the reference pump drain amount, the process proceeds to step S10.

  In step S <b> 9, the hydraulic device 14 executes a process for notifying that an abnormality has occurred in the pump unit 15. For example, the main control unit 52 causes the pump lamp 69 to blink.

  In step S <b> 10, the hydraulic device 14 executes a process for notifying that an abnormality has occurred in the hydraulic circuit 16. For example, the main controller 52 causes the hydraulic circuit lamp 70 to blink.

  After the execution of step S10, it is possible to perform only the diagnosis with less burden by finishing the abnormality diagnosis process. However, in this embodiment, when an abnormality of the hydraulic circuit 16 is detected by step S10, the burden increases, but the steps after S11 are performed in order to identify the abnormality target device.

  In steps S <b> 11 and S <b> 12, the hydraulic device 14 activates a device to be diagnosed by the hydraulic circuit 16. For example, the main control unit 52 operates a plurality of control valves (31, 32, 33, etc.) sequentially or in parallel with a predetermined operation. This operation is performed for a predetermined time, during which the drain amount of the device (a plurality of control valves) to be diagnosed is detected. The supply amount of the hydraulic fluid to the hydraulic circuit 16 at this time may be the diagnostic supply amount Ft or may be larger than the diagnostic supply amount Ft.

  In steps S13 and S14, the hydraulic pressure device 14 sequentially determines whether or not the drain amount detected in each control valve is less than the reference valve drain amount set for each control valve for all the control valves. judge.

  In step S15, the hydraulic pressure device 14 performs a process of notifying that an abnormality has occurred in the control valve determined in step S13 that the detected drain amount is not less than the reference valve drain amount. For example, the main control unit 52 blinks the valve lamp 71 corresponding to the control valve in which an abnormality has occurred.

According to the above embodiment, the hydraulic device 14 of the die casting machine 1 includes the pump 19, the hydraulic circuit 16 to which the hydraulic fluid is supplied from the pump 19, and the hydraulic fluid from the pump 19 through the hydraulic circuit 16. By supplying a hydraulic cylinder 13 to be supplied, a pressure sensor 26 for detecting the pressure of the hydraulic circuit 16, and a predetermined driving supply amount (F ₁ ) in the molding cycle, the hydraulic fluid is discharged from the pump 19. It has a control device 17 for controlling the pump 19 and the hydraulic circuit 16 so that the hydraulic cylinder 13 is driven. The control device 17 discharges from the pump 19 a predetermined diagnostic supply amount Ft that is greater than the rated external leakage amount F ₀ of the hydraulic fluid in the hydraulic circuit 16 and less than the drive supply amount (F ₁ ). The pump 19 is controlled as described above, and when the detected pressure of the pressure sensor 26 at that time is less than a predetermined reference pressure P ₀ , processing for notifying that an abnormality has occurred is performed.

  Therefore, it is possible to detect the abnormality of the hydraulic circuit 16 by supplying the hydraulic fluid with a relatively small supply amount. Further, it is not necessary to drive a member (for example, the movable die plate 8 or the injection plunger 10) connected to the hydraulic cylinder 13. As a result, an abnormality in the hydraulic circuit can be detected with a small burden. In addition, the abnormality detection of this embodiment can respond to both the abnormality which arises by progress of normal wear, and the abnormality which arises suddenly.

The hydraulic device 14 further includes a pump flow sensor 27 that detects the drain amount of the pump 19. The control device 17 controls the pump 19 to be driven at a predetermined rotational speed and a predetermined capacity. When the detected pressure at that time is less than the reference pressure P ₀ , the detected flow rate of the pump flow sensor 27 is When the amount is less than the predetermined reference pump drain amount, a process for notifying that an abnormality has occurred in the hydraulic circuit 16 is performed (step S10), and the detected flow rate of the pump flow sensor 27 is equal to or greater than the reference pump drain amount Performs a process of notifying that an abnormality has occurred in the pump 19 (step S9).

  Accordingly, the supply of the hydraulic fluid for diagnosis Ft is simply performed, and abnormality detection is performed. That is, it is possible to provide a flow rate sensor for detecting the amount of hydraulic fluid supplied to the hydraulic circuit 16 and maintain the supply amount at the diagnostic supply amount Ft by feedback control (this aspect is also included in the present invention). Not done. Furthermore, it is possible to detect an abnormality including an abnormality of the pump 19 with a small supply amount, and it is possible to specify a failure location.

The hydraulic circuit 16 has a plurality of control valves (31, 32, 33). The hydraulic device 14 is provided with a plurality of valve flow sensors 35 for detecting drain amounts of a plurality of control valves. In the case where the detected pressure when the pump 19 is controlled so that the hydraulic fluid of the diagnostic supply amount Ft is discharged is less than the reference pressure P ₀ , the control device 17 performs the control in any of the plurality of control valves. When the detected flow rate of the valve flow sensor 35 corresponding to the valve exceeds a predetermined reference valve drain amount set for each of the plurality of control valves, processing for notifying that an abnormality has occurred in the control valve is performed ( Step S15).

  Accordingly, the abnormality of the entire hydraulic circuit 16 is detected by detecting the abnormality with a small supply amount, and when the abnormality is detected, the location where the abnormality is detected in the hydraulic circuit 16 can be specified. That is, a detailed abnormality can be detected efficiently.

The control device 17 holds a database 63 in which the pressure is associated with the number of molding cycles. Further, the control device 17 refers to the database 63 to identify and identify the cycle number n ₁ corresponding to the detected pressure when the pump 19 is controlled such that the diagnostic supply amount Ft of hydraulic fluid is discharged. A process of notifying information based on the difference n ₂ between the cycle number n ₁ and the predetermined limit cycle number n ₀ is performed (step S6).

  Therefore, it is possible to predict the timing of occurrence of abnormality due to the progress of normal wear. As a result, the worker can know the appropriate time for maintenance, and the convenience of the worker is improved. In addition, since the sign is performed based on the operation for detecting the abnormality, the hydraulic system is not operated only for the sign and the operation is less burdened as described above. The burden on the device is reduced.

  The hydraulic device 14 has a temperature sensor 25 that detects the temperature of the hydraulic fluid. The control device 17 increases the diagnostic supply amount Ft in accordance with an increase in the temperature detected by the temperature sensor 25. Therefore, errors in abnormality diagnosis caused by temperature can be suppressed. As a result, accurate abnormality detection is possible even when abnormality detection is performed with a relatively small supply amount.

(Second Embodiment)
FIG. 8 is a block diagram showing a configuration of a hydraulic system and a signal processing system of the hydraulic device 114 of the die casting machine according to the second embodiment. FIG. 8 corresponds to a part of FIG. 3 of the first embodiment.

  The hydraulic device 114 is different from the hydraulic device 14 of the first embodiment in that at least one valve flow sensor 35 is provided so as to detect the drain amount of two or more control valves. Other configurations are the same as those of the hydraulic device 14 of the first embodiment.

  Specifically, the first valve flow sensor 35A detects the drain amount of the entire first valve group 75A including the first switching valve 31A and the second switching valve 31B. The second valve flow sensor 35 </ b> B detects the drain amount of the entire second valve group 75 </ b> B including the pressure reducing valve 32 and the check valve 33.

  The operation of the hydraulic device 114 is substantially the same as the operation of the hydraulic device 14 of the first embodiment. However, in steps S <b> 13 to S <b> 15 of FIG. 7, the control device 17 sequentially determines the flow rate detected by each valve flow sensor 35 for each valve group 75 so that the reference valve drain amount set for each valve group 75. It is determined whether it is less than or not. And the control apparatus 17 performs the process which alert | reports that abnormality had arisen in the valve group 75 determined with the detected flow volume not being less than the reference | standard valve drain amount. For example, the valve lamp 71 corresponding to the control valve included in the valve group 75 in which an abnormality has occurred is blinked.

  According to the above embodiment, since a plurality of control valves are grouped into a plurality of valve groups and the drain amount is detected and the abnormality is detected for each valve group, the number of flow sensors can be reduced and the cost can be reduced. . At this time, as in the embodiment, the electromagnetic pilot valves (31A, 31B) and the pilot valves (32, 33) are grouped for each operation method such as separate groups, or the switching valves (31A, 31B) Abnormalities can be detected efficiently and accurately by grouping the valves (32, 33) other than the valve groups (32, 33) for each type related to the valve structure.

  The present invention is not limited to the above embodiment, and may be implemented in various aspects.

  The molding machine is not limited to a die casting machine. For example, the molding machine may be another metal molding machine, a plastic injection molding machine, or a molding machine that molds a material obtained by mixing wood powder with a thermoplastic resin or the like. Good.

  Further, the molding machine is not limited to horizontal mold clamping horizontal injection, and may be vertical mold clamping vertical injection or horizontal mold clamping vertical injection, for example. The molding machine is not limited to a toggle type, and may be, for example, a hybrid type in which mold closing and clamping are performed by separate driving means.

  The time when the abnormality diagnosis is performed is not limited to the time when the molding machine is operating and the time when the operator is arbitrary. For example, the abnormality diagnosis may be performed periodically, such as being performed for each molding cycle or performed for a predetermined number of molding cycles. In such a case, the abnormality diagnosis is preferably performed simultaneously with a process in which a hydraulic actuator such as a hydraulic cylinder is not used (for example, a spray process in the embodiment).

  The state of the hydraulic circuit when supplying the diagnostic supply amount of hydraulic fluid (steps S1 to S4) is not limited to a state where the flow of hydraulic fluid to an actuator such as a hydraulic cylinder is interrupted. For example, in a state where the flow of hydraulic fluid is allowed to further drive the hydraulic cylinder that has reached the drive limit on one side to the one side, the hydraulic fluid is substantially transferred from the hydraulic circuit to the hydraulic cylinder. Does not flow, and the pressure in the hydraulic circuit rises. However, in this case, it is necessary to set the supply amount for diagnosis in consideration of leakage of hydraulic fluid in the hydraulic cylinder.

  When supplying a diagnostic supply amount of hydraulic fluid (steps S <b> 1 to S <b> 4), the flow permitting and blocking states (the state of each valve, etc.) in the hydraulic circuit may be set as appropriate. For example, when two valves capable of allowing and shutting off the flow of hydraulic fluid are provided in series with respect to one hydraulic cylinder 13, the flow may be shut off only in one of the valves. Alternatively, the flow may be interrupted at both valves. Alternatively, diagnosis may be performed by blocking only at one valve and then performing diagnosis only at the other valve. The state of each valve may be set as appropriate in consideration of the relative ease of occurrence of a relative abnormality between a plurality of valves, the state in which abnormality is likely to occur in each valve, and the like.

  The pressure of the hydraulic circuit detected at the time of abnormality diagnosis is not limited to the pressure upstream of the hydraulic circuit (between the pump and the hydraulic circuit, upstream of the most upstream control valve capable of blocking the flow). For example, as described above, when two valves capable of blocking the flow are arranged in series, the pressure may be detected between the two valves. Any position can be used as long as the pressure drop accompanying the increase in the amount of external leakage can be detected. Similarly, the temperature of the hydraulic fluid is not limited to the temperature upstream of the hydraulic circuit, and may be detected at an appropriate position.

  The pump should just be able to adjust the hydraulic fluid supplied to a hydraulic circuit by either rotation speed or the capacity | capacitance per cycle of a pump. That is, the pump may be of a fixed type. The electric motor may not be a servo motor.

  The pressure sensor and the flow sensor are not limited to those that output a multi-value signal, and may output a binary signal. For example, the pressure sensor may be a pressure switch that outputs an ON signal (or an OFF signal) when the pressure reaches a reference pressure. Similarly, the flow sensor may be a flow switch that outputs an ON signal (or an OFF signal) when the reference drain amount is reached.

  The device for notification is not limited to a display device that performs visual notification. For example, notification may be performed by a notification sound output from a speaker.

  It is only necessary that at least one valve group has two or more control valves. This is because if at least two control valves measure the drain amount together, the flow rate sensor can be reduced.

  DESCRIPTION OF SYMBOLS 1 ... Die-casting machine, 13 ... Hydraulic cylinder, 14 ... Hydraulic device, 16 ... Hydraulic circuit, 17 ... Control device, 19 ... Pump, 26 ... Pressure sensor

Claims (6)

A hydraulic device for a molding machine,
A pump,
A hydraulic circuit to which hydraulic fluid is supplied from the pump;
A hydraulic cylinder to which hydraulic fluid is supplied from the pump via the hydraulic circuit;
A pressure sensor for detecting the pressure of the hydraulic circuit;
A control device that controls the pump and the hydraulic circuit so that the hydraulic cylinder is driven by discharging a predetermined amount of hydraulic fluid from the pump in a molding cycle;
Have
The control device is configured so that a predetermined diagnostic supply amount of hydraulic fluid that is greater than the rated external leakage amount of the hydraulic fluid in the hydraulic circuit and less than the drive supply amount is discharged from the pump. And a hydraulic pressure device for a molding machine that performs processing for notifying that an abnormality has occurred when the detected pressure of the pressure sensor is less than a predetermined reference pressure. A pump flow sensor for detecting a drain amount of the pump;
The controller is
In the case where the pump is controlled to be driven at a predetermined rotational speed and a predetermined capacity, and the detected pressure at that time is less than the reference pressure,
When the detected flow rate of the pump flow sensor is less than a predetermined reference pump drain amount, a process of notifying that an abnormality has occurred in the hydraulic circuit is performed,
The hydraulic device for a molding machine according to claim 1, wherein when the detected flow rate of the pump flow sensor is equal to or greater than the reference pump drain amount, processing for notifying that an abnormality has occurred in the pump is performed. The hydraulic circuit has a plurality of control valves,
A plurality of valve flow sensors for detecting drain amounts of the plurality of control valves are provided;
The controller is
In the case where the detected pressure when the pump is controlled such that the diagnostic supply amount of hydraulic fluid is discharged is less than the reference pressure,
In any one of the plurality of control valves, when the detected flow rate of the valve flow sensor corresponding to the control valve exceeds a predetermined reference valve drain amount set for each of the plurality of control valves, the control valve The hydraulic device for a molding machine according to claim 1 or 2, wherein a process for notifying that an abnormality has occurred is performed. The hydraulic circuit has a plurality of valve groups including a valve group having a plurality of control valves and a valve group having at least one control valve,
A plurality of valve flow sensors for detecting drain amounts of the plurality of valve groups are provided;
The controller is
In the case where the detected pressure when the pump is controlled such that the diagnostic supply amount of hydraulic fluid is discharged is less than the reference pressure,
In any one of the plurality of valve groups, when the detected flow rate of the plurality of valve flow sensors corresponding to the valve group exceeds a predetermined reference valve drain amount set for each of the plurality of valve groups, The hydraulic device for a molding machine according to claim 1 or 2, wherein a process for notifying that an abnormality has occurred in the valve group is performed. The controller is
Maintains a database that correlates pressure with the number of molding cycles,
Referring to the database, the number of cycles corresponding to the detected pressure when the pump is controlled so that the diagnostic supply amount of hydraulic fluid is discharged is specified, and the specified number of cycles and a predetermined limit cycle The hydraulic device for a molding machine according to any one of claims 1 to 4, wherein a process for notifying information based on a difference from the number is performed. A temperature sensor for detecting the temperature of the hydraulic fluid;
The hydraulic device for a molding machine according to any one of claims 1 to 5, wherein the control device increases the supply amount for diagnosis according to an increase in temperature detected by the temperature sensor.

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