JP3268432B2 - Hydraulic pump protection device for injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pump protection device for an injection molding machine which detects an overload of a pump motor for driving a hydraulic pump and performs an overload process corresponding to the overload.

[0002]

2. Description of the Related Art Generally, a hydraulic injection molding machine incorporates a hydraulic circuit including a hydraulic pump, and drives various actuators such as an injection cylinder by the hydraulic circuit. By the way, as the hydraulic pump, a hydraulic pump having an appropriate size according to the performance of the injection molding machine is selected in order to suppress the cost and to avoid unnecessary enlargement. Accordingly, the hydraulic pump may be overloaded, and usually includes a hydraulic pump protection device for preventing the pump motor from burning due to the overload.

Conventionally, as this type of hydraulic pump protection device, a thermal relay connected to a power supply line of a pump motor has been known. The thermal relay has a function of, when an overcurrent flows through a power supply line due to an overload, displacing the bimetal due to a temperature that rises due to the overcurrent and interrupting power supply to the pump motor.

[0004]

However, the conventional hydraulic pump protection device using the above-described thermal relay operates according to the temperature, and thus may malfunction if the temperature rises, for example. . In particular, an injection molding machine installed in a factory or the like is likely to malfunction due to an increased room temperature. If a malfunction occurs, the operation of the injection molding machine stops, causing a drop in productivity due to the interruption of production, and a problem that the molding conditions are delicately changed due to the interruption, thereby lowering the molding quality. there were.

The present invention has been made to solve the problems existing in the prior art, and it is possible to reliably avoid the adverse effect of stopping the hydraulic pump due to a malfunction, thereby improving the productivity and the molding quality. An object of the present invention is to provide a hydraulic pump protection device for an injection molding machine that is excellent in low cost and versatility, such as being easily applicable to existing injection molding machines.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a hydraulic pump of an injection molding machine M which detects an overload of a pump motor 3 for driving a hydraulic pump 2 and performs an overload process corresponding to the overload. In configuring the protection device 1, the electric energy Sm is calculated from the discharge flow rate Q and the discharge pressure P during operation of the hydraulic pump 2, and the electric energy Sm reaches a second set value Sb for detecting a state immediately before overload. If so, the preliminary processing is performed, and the power amount Sm is equal to the first set value Sa for detecting the overload.
The control unit 4 is provided with a control unit 4 for performing an overload process when the number of times has reached.

In this case, according to a preferred embodiment, as a preliminary process, an operation process of a preliminary alarm 8a for notifying a state immediately before an overload can be performed. On the other hand, the control unit 4 includes a thermal relay 6 that is connected to the power supply line 5 of the pump motor 3 and shuts off power supply when an overload occurs. The power amount Sm reaches the first set value Sa, and power supply is performed by the thermal relay 6. If it is shut off, for example, the operation process (overload process) of the overload alarm 8b for notifying the overload can be performed. Further, the control unit 4 includes an air temperature sensor 7, and the air temperature Tm detected by the air temperature sensor 7 is a warning temperature set value T.
If the power is cut off by the thermal relay 6 in a state where the power has reached u and the electric energy Sm has not reached the third set value Sc, for example, the operation processing of the malfunction alarm 8d for notifying malfunction (malfunction processing). Can be performed.

Thus, the control unit 4 controls the hydraulic pump 2
The amount of power Sm is calculated from the discharge flow rate Q and the discharge pressure P at the time of the operation of, and a preliminary process associated with the power amount Sm reaching the second set value Sb for detecting a state immediately before the overload is performed. Since the necessary countermeasures can be taken before the occurrence of the overload, the occurrence of the overload itself can be avoided. On the other hand, the electric energy S
When m reaches the first set value Sa for detecting an overload, an overload process, specifically, a power supply stop process for the pump motor 3 or an overload alarm 8b for notifying the overload is activated. Therefore, malfunction does not occur due to environmental changes such as an increase in the temperature of the room in which the injection molding machine M is installed, and the adverse effect of stopping the hydraulic pump 2 and interrupting the operation of the injection molding machine M is reliably avoided. You.

Incidentally, if the overload processing is performed in response to the power amount Sm reaching the first set value Sa and the power supply is cut off by the thermal relay 6, the processing based on the results of two different overload detection systems is performed. Because of the double protection,
The reliability can be further improved. Further, a malfunction operation associated with the interruption of power supply by the thermal relay 6 in a state where the temperature Tm detected by the temperature sensor 7 has reached the alarm temperature set value Tu and the electric energy Sm has not reached the third set value Sc. , The operation of the injection molding machine M can be promptly returned (manual return or automatic return).

[0010]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, a schematic configuration of an injection molding machine M provided with a hydraulic pump protection device 1 according to the present embodiment will be described with reference to FIG.

In FIG. 1, reference numeral 50 denotes an injection device, which constitutes an injection molding machine M together with a mold clamping device (not shown). Injection device 50
Has a heating cylinder 53 provided with an injection nozzle 51 at a front end and a hopper 52 at a rear part, and a screw 54 is built in the heating cylinder 53. Also, at the rear end of the heating cylinder 53,
A screw drive unit 55 that drives the screw 54 to rotate and advance / retreat is provided. The screw driving section 55 includes an injection cylinder 57 having a piston 56 built therein.
The front end of r is connected to the rear end of the screw 54,
The rear end of the piston rod 56r is spline-coupled to a shaft of an oil motor 58 disposed at the rear end of the injection cylinder 57.

On the other hand, reference numeral 60 denotes a hydraulic circuit,
Is provided. Reference numeral 3 denotes a pump motor for driving the hydraulic pump 2, which is connected to a power supply via a power supply line 5. The hydraulic pump 2 and the oil tank 62 are connected to a front oil chamber and a rear oil chamber of the injection cylinder 57 via a four-port switching valve 61. In FIG. 1, the hydraulic circuit connected to the oil motor 58 and other detailed circuit components are omitted.

Next, the configuration of the hydraulic pump protection device 1 according to this embodiment will be specifically described with reference to FIGS.

The hydraulic pump protection device 1 has a control unit 4. The control unit 4 includes an arithmetic processing unit 10, and the arithmetic processing unit 10 can use a microprocessor or the like having a computer processing function. Further, a thermal relay 6 is connected in the middle of the power supply line 5. The thermal relay 6 has a function of, when an overcurrent flows through the power supply line 5 due to an overload, displacing the bimetal due to a temperature rising due to the overcurrent, and interrupting the power supply to the pump motor 3. The ON / OFF signal indicating the state of the thermal relay 6 is sent to the arithmetic processing unit 1
0 is added.

On the other hand, since the hydraulic pump 2 usually has a pump monitor output section 11, the discharge flow rate Q and discharge pressure P of the hydraulic pump 2 obtained from the pump monitor output section 11 are obtained.
Is given to the arithmetic processing unit 10. When the pump monitor output unit 11 is not provided, the detection result of the discharge pressure P can be obtained from the pressure sensor 12 connected to the discharge line of the hydraulic pump 2. Further, the injection speed is obtained from the position detection result of the piston 56 of the injection cylinder 57 obtained from the position sensor 13, and the flow rate for the injection cylinder 57 can be obtained based on the injection speed.
Similarly, information relating to the discharge flow rate Q can be obtained from the sum of the flow rates for the other actuators obtained. The reason why such information relating to the discharge flow rate Q and the discharge pressure P of the hydraulic pump 2 is required is to calculate the electric energy Sm when the hydraulic pump 2 operates. As described above, by directly or indirectly obtaining information related to the discharge flow rate Q and the discharge pressure P from the hydraulic circuit 60, it is not necessary to connect a dedicated power meter to the power supply line 5, so that the existing injection The hydraulic pump protection device 1 according to the present invention can be easily applied to a molding machine.

On the other hand, a first set value Sa for detecting whether the power amount Sm is a normal power amount or an overload state power amount is set in the arithmetic processing unit 10 in advance,
Further, a second set value Sb for detecting whether or not the electric energy Sm is just before the overload is set.

Reference numeral 7 denotes an air temperature sensor, and the detection result of the air temperature Tm is provided to the arithmetic processing unit 10. On the other hand, in the arithmetic processing unit 10, a warning temperature set value Tu at which the temperature Tm may cause a malfunction of the thermal relay 6 is set. In this case, the alarm temperature setting value Tu is usually set to a temperature higher than the normal temperature. On the other hand, the output side of the arithmetic processing unit 10 is connected to the display unit 8. The display unit 8 includes a preliminary alarm 8a, an overload alarm 8b, an abnormal alarm 8c, and a malfunction alarm 8d as shown in FIG.

Next, the operation of the hydraulic pump protection device 1 according to the present embodiment will be described with reference to FIGS.

First, information relating to the discharge flow rate Q and the discharge pressure P of the hydraulic pump 2 output from the pump monitor output section 11 is given to the arithmetic processing section 10, and the electric energy Sm when the hydraulic pump 2 operates is calculated as Sm. [Kw] = P [MPa]
× Q [liter / min] × 1/60. Note that such an electric energy Sm can also be obtained from the pressure sensor 12 and the position sensor 13 in the hydraulic circuit 60 as described above.

The state of the thermal relay 6, that is, an ON signal indicating a power supply state in a normal state or an OFF signal indicating a power supply cutoff state in an overload state is calculated by the arithmetic processing unit 10.
And the temperature Tm (detection result) detected by the temperature sensor 7 is also provided to the arithmetic processing unit 10.

On the other hand, the arithmetic processing unit 10 calculates the calculated electric energy Sm, an ON / OFF signal obtained from the thermal relay 6,
The detected temperature Tm is monitored, and necessary processing, that is, alarm activation processing (display processing) is executed. In the table shown in FIG. 2, a mark “○” indicates a case where an abnormality is detected. In the case of the thermal relay 6, the OFF signal is applied. In the case of the electric energy Sm, the case where the first set value Sa is reached. , The temperature Tm indicates the time when the alarm temperature set value Tu is reached.

Now, the hydraulic pump 2 is operated normally, an ON signal is given from the thermal relay 6 to the arithmetic processing unit 10, the electric energy Sm does not reach the first set value Sa, and the temperature Tm is also a warning temperature. If the set value Tu has not been reached, none of the alarms 8a to 8d is turned on.

On the other hand, as shown in FIG.
When m reaches the second set value Sb for detecting the state just before the overload, the arithmetic processing unit 10 executes the operation process (preliminary process) for lighting the preliminary alarm 8a and notifies the state just before the overload. Thus, necessary measures can be taken before an overload occurs, so that the occurrence of the overload itself can be avoided.

Further, when the power amount Sm reaches the first set value Sa for detecting an overload, an operation process (overload process) for turning on the overload alarm 8b is executed to notify the overload. In this case, the overload alarm 8b is turned on, but the thermal relay 6 keeps supplying power.
The operation of is continued. Therefore, for example, the worker
At this point, necessary overload processing can be appropriately performed, such as manually stopping the pump motor 3 or stopping the pump motor 3 after a predetermined quantity of production has been performed.

On the other hand, as shown in FIG.
If the power is cut off by the thermal relay 6 in addition to the fact that m reaches the first set value Sa, the pump motor 3 stops in addition to the lighting of the overload alarm 8b. In this case, double protection is achieved by processing based on the results of two different overload detection systems, so that reliability can be further improved.

Further, as shown in FIG. 2C, the temperature Tm obtained from the temperature sensor 7 reaches the alarm temperature set value Tu,
If the power is cut off by the thermal relay 6 in a state where the electric energy Sm has not reached the third set value Sc, the malfunction is likely to occur due to a rise in temperature, and the malfunction alarm 8d for notifying the malfunction is activated. Execute processing (malfunction operation processing). Thereby, the operation of the injection molding machine M can be promptly returned (manual return or automatic return). In addition,
The third set value Sc is the first set value Sa or the second set value Sb
May be used, or may be set separately.

Further, as shown in FIG. 2D, although the power supply is cut off by the thermal relay 6, the electric energy Sm does not reach the first set value Sa (or the second set value Sb) and the temperature Tm If the alarm temperature does not reach the alarm temperature set value Tu, the failure of the thermal relay 6 is considered, and the operation process for lighting the abnormal alarm 8c is executed.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
It is possible to arbitrarily change, add, and delete the details of the configuration, the method, and the like without departing from the gist of the present invention.

For example, as a process of the control unit 4, FIG.
Although four examples of (a) to (d) have been described, other combinations and display methods based on alarms based on these combinations can be arbitrarily implemented. Further, as the processing of the control unit 4, an example in which an alarm is turned on has been described, but any processing such as output of a control command can be applied.

[0031]

As described above, the hydraulic pump protection device for an injection molding machine according to the present invention calculates the electric energy from the discharge flow rate and the discharge pressure when the hydraulic pump is operating, and calculates the electric energy before the overload. When the power reaches the second set value for detecting the state, the preparatory process is performed, and when the power amount reaches the first set value for detecting the overload, the control unit that performs the overload process is provided. It has a remarkable effect.

[0032] The adverse effect of stopping the hydraulic pump due to a malfunction can be reliably avoided, and productivity and molding quality can be improved.

It is excellent in low cost and versatility, for example, it can be easily applied to existing injection molding machines.

Since preparatory processing is performed when the amount of power reaches a second set value for detecting a state immediately before an overload, necessary measures can be taken before an overload occurs.
The occurrence of overload itself can be avoided.

According to a preferred embodiment, a thermal relay is provided which is connected to a power supply line of a pump motor and cuts off power supply in the event of an overload, the amount of power reaches a first set value, and power supply is cut off by the thermal relay. By performing the overload processing associated therewith, double protection is achieved by processing based on the results of two different overload detection systems, so that reliability can be further improved.

According to a preferred embodiment, the power supply is cut off by the thermal relay in a state in which the air temperature sensor is provided, and the air temperature detected by the air temperature sensor has reached the alarm temperature set value and the electric energy has not reached the third set value. By performing a malfunction process associated with this, the operation of the injection molding machine can be promptly returned (manual return or automatic return).

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a hydraulic pump protection device according to an embodiment;

FIG. 2 is an operation explanatory view of the hydraulic pump protection device,

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic pump protection device 2 Hydraulic pump 3 Pump motor 4 Control part 5 Power supply line 6 Thermal relay 7 Temperature sensor 8a Preliminary alarm 8b Overload alarm 8d Malfunction alarm M Injection molding machine

Claims (6)

(57) [Claims] 1. A hydraulic pump protection device for an injection molding machine that detects an overload of a pump motor that drives a hydraulic pump and performs an overload process corresponding to the overload. Calculate the electric energy from the discharge pressure, perform the preliminary processing if the calculated electric energy reaches the second set value to detect the state before the overload, and the electric energy to the first set value to detect the overload If you reach
A hydraulic pump protection device for an injection molding machine, comprising a control unit for performing the overload processing. 2. The hydraulic pump protection device for an injection molding machine according to claim 1, wherein said preliminary processing is an operation processing of a preliminary alarm for notifying a state immediately before an overload. 3. The control unit includes a thermal relay connected to a power supply line of the pump motor to cut off power supply when an overload occurs, wherein the power amount reaches the first set value and power is supplied by the thermal relay. 2. The hydraulic pump protection device for an injection molding machine according to claim 1, wherein the overload processing is performed when the pressure is shut off. 4. The overload process according to claim 3, wherein the overload process is an overload alarm operation process for notifying an overload.
A hydraulic pump protection device for an injection molding machine as described in the above. 5. The control unit includes an air temperature sensor, and supplies power by the thermal relay in a state where the air temperature detected by the air temperature sensor has reached a warning temperature set value and the electric energy has not reached a third set value. 4. The hydraulic pump protection device for an injection molding machine according to claim 3, wherein a malfunction process corresponding to the malfunction is performed when the control is interrupted. 6. The malfunction process according to claim 5, wherein the malfunction process is a malfunction alarm that notifies malfunction.
A hydraulic pump protection device for an injection molding machine as described in the above.