JP5882848B2 - Heater power measuring device for injection molding machine - Google Patents

Description

  The present invention relates to an injection molding machine that measures the power consumed by a heater that melts the resin in the injection cylinder and the heater that maintains the molten state of the resin flowing in the mold. Relates to the device.

  The plastic injection molding machine is a machine for producing plastic parts by melting solid resin pellets by heat of a heater and shearing heat generated by screw rotation, and injecting the molten resin into a mold. When the resin is melted, energy is consumed by the rotation of the heater and screw. In the case of an electric injection molding machine with excellent energy-saving performance, the energy consumed by the heater is the majority of the energy consumed by the entire machine. Accounted for. It is important to understand power consumption in order to save energy and to understand the manufacturing cost of parts. However, in order to accurately grasp power consumption, the power of the heater is particularly accurately grasped for the above reasons. It is important to.

  As a first conventional technique for grasping the power consumption of the heater, Patent Document 1 discloses that the power supply voltage and current of the heater are measured and the power consumed by the heater is obtained from these. Further, as a second conventional technique for grasping the power consumption of the heater, Patent Document 2 discloses that the power consumption of the heater is obtained from the energization time during one molding cycle and the power (constant) in the heater specifications. Yes. As a power measuring device for an injection molding machine, Patent Document 3 discloses a technique for measuring the power and power of a servo motor by measuring the voltage and current of a servo amplifier in the same manner as a heater.

JP 2009-172822 A JP 2000-206150 A JP 2002-192588 A

The first conventional technique for measuring the power supply voltage and current of the heater and determining the power consumed by the heater is based on the measured current and voltage even if the power (constant) in the heater specifications is unknown. There is an advantage that the power consumption of the heater can be obtained accurately. However, since the current flowing through the heater needs to be measured for each heater by the current detector, there is a problem that the cost increases because the number of current detectors increases as the number of heaters increases.
On the other hand, the second conventional technique for obtaining the power consumed by the heater from the energizing time during one molding cycle and the power (constant) in the heater specifications is only required to measure the energizing time of the heater. If the temperature control device controls the temperature by controlling the temperature, it is possible to easily measure the energization time, so that it is possible to measure the power at a low cost. Here, the power (constant) on the specification of the heater used for calculating the power consumption in the second prior art is the power when the rated voltage is supplied to the heater. Therefore, if the supply voltage is the same as the rated voltage, there is no problem even if the heater power (constant) in the specification is used as it is and the power is obtained, but the heater power is treated as a constant despite the voltage fluctuation. And there was a problem that the power consumption calculated by the calculation deviated from the reality. Voltage fluctuations are likely to occur in areas where it is difficult to supply high-quality power.

  Therefore, in view of the above-described problems of the prior art, the present invention is an injection molding machine capable of measuring the power consumption of a heater accurately and in real time by an inexpensive method even in an environment where the voltage supplied to the heater fluctuates. It is an object to provide a heater power measuring device.

The invention according to claim 1 of the present application is a heater power measuring device of an injection molding machine having a heater, wherein the heater power measuring device includes a resistance value storage unit that stores a resistance value on a specification of the heater; A voltage measurement unit that measures a voltage supplied to the heater; and an energization time ratio measurement unit that measures a ratio of energization time during which the heater is energized within a predetermined period, and the voltage measurement unit includes the injection molding machine A voltage measurement unit for measuring a voltage supplied to the upper servo amplifier, wherein the power consumption of the heater is obtained from the resistance value, the measured voltage, and the measured heater energization time ratio. This is a heater power measuring device for an injection molding machine.
The invention according to claim 2 is a heater power measuring device of an injection molding machine having a heater, wherein the heater power measuring device includes a rated voltage storage unit that stores a rated voltage of the heater, and a heater power at the rated voltage. A heater power storage unit that stores the voltage, a voltage measurement unit that measures a voltage supplied to the heater, and an energization time rate measurement unit that measures a rate of energization time that the heater energized within a predetermined period. The voltage measuring unit is a voltage measuring unit that measures a voltage supplied to a servo amplifier on the injection molding machine, and the measured voltage and heater power at the rated voltage, the measured voltage, and the measured voltage. The heater power measuring device for an injection molding machine is characterized in that the power consumption of the heater is obtained from the ratio of the heater energization time.

  According to the present invention, it is possible to provide a heater power measuring device for an injection molding machine capable of measuring the power consumption of the heater accurately and in real time by an inexpensive method even in an environment where the voltage supplied to the heater fluctuates.

It is a figure explaining embodiment which measures the supply voltage to a heater. It is a figure explaining embodiment using the servo amplifier provided with the voltage measurement part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a method for calculating power consumption in the present invention will be described. In the present invention, the heater power measurement method disclosed in Patent Document 2 which is the second prior art is improved by taking into account voltage fluctuations, and accurate power consumption is obtained in real time. The first invention of the present invention will be described in detail below. If the heater resistance value (R) in the specification is known in advance, the power consumption (Wt) of the heater can be obtained only by measuring the ratio (H) of the measured heater energization time and the measured voltage (Vt). it can. The ratio (H) of the energization time of the heater is obtained by measuring the time during which the heater is energized within the period for each sampling period.

  In the first invention of the present invention, this (Equation 1) is used to accurately determine the power consumption even if there is no means for measuring the current (current measurement unit). Here, the resistance value (R) of the heater in the specification is stored in advance in a memory on the injection molding machine for each heater zone.

Wt = H · Vt ² / R (Formula 1)
Vt: Voltage (actual measured value)
Wt: Heater power consumption (actual measured value)
H: Ratio of heater energization time (%)
R: Heater resistance value on specifications (constant)

Further, the heater power at the rated voltage is expressed by (Equation 2).
Wr = Vr ² / R (Formula 2)
Vr: Rated voltage Wr: Heater power on specifications at rated voltage Vr

  From Equations 1 and 2, the heater power consumption (actually measured value) Wt is represented by (Equation 3). That is, if the heater power (Wr) and the rated voltage (Vr) on the specifications are known in advance, the power consumption of the heater can be measured only by measuring the ratio (H) of the measured heater energization time and the measured voltage (Vt). (Wt) can be obtained.

In the second invention of the present invention, this (Equation 3) is used to accurately determine the power consumption even if there is no means for measuring the current (current measurement unit). Here, the rated voltage (Vr) and the heater power (Wr) on the specifications at the rated voltage Vr are stored in advance in the memory of the injection molding machine for each heater zone.
Wt = H · Wr · (Vt / Vr) ² (Formula 3)

  In this case, it is preferable to directly measure the voltage supplied to the heater drive circuit. However, if the voltage is on the same power supply line as the power supply line to the heater, the voltage on the injection molding machine May be measured. For example, when the servo amplifier has a voltage measuring unit as disclosed in Patent Document 3, the voltage measured by the servo amplifier may be used as it is. In this case, the heater power measurement unit according to the present invention and the voltage measurement unit of the servo amplifier are provided in the same control device, and the voltage measured by the servo amplifier is supplied to the heater power measurement unit via the internal bus of the control device. The power can be measured by transferring to. Alternatively, the voltage measured by the voltage measurement unit of the servo amplifier may be written in a memory that can be referred to by the heater power measurement unit, and the power consumption may be obtained by reading the voltage measured by the heater power measurement unit. The voltage measurement unit of the servo amplifier may measure the AC voltage supplied to the servo amplifier and use it as it is, or measure and measure the voltage after being converted from AC to DC in the servo amplifier. The DC voltage may be converted into an AC voltage supplied to the servo amplifier.

Hereinafter, an embodiment of the present invention will be described with reference to block diagrams of an injection molding machine shown in FIGS. FIG. 1 is a diagram illustrating an embodiment for measuring a supply voltage to a heater.
A nozzle 1 is attached to the tip of the injection cylinder 2, and a screw 3 is inserted into the injection cylinder 2. A heater 4 is attached to the nozzle 1, and heaters 5 </ b> A and 5 </ b> B are attached to the injection cylinder 2 in order to heat the axial direction divided into a plurality of heating zones. A temperature detector 6 such as a thermocouple is attached to the nozzle 1, and temperature detectors 7 A and 7 B such as a thermocouple are attached to the injection cylinder 2. The temperature of each part is detected by each temperature detection part 6, 7A, 7B. The screw 3 is provided with a pressure sensor 28 such as a load cell that detects the pressure applied to the screw 3 in order to measure the resin pressure in the injection cylinder 2.

  The screw 3 moves in the axial direction or rotates about the axis by the driving force of the servo motor 29. A servo motor 29 is provided with a position / speed detector 30 for detecting a position / speed in the axial direction or around the axis. Here, the servo motor 29 is a generic term for an injection servo motor and a metering servo motor.

  The control device 10 includes a CNC CPU 20 which is a microprocessor for numerical control, a PMC CPU 17 which is a microprocessor for a programmable machine controller, and a servo CPU 11 which is a microprocessor for servo control. By selecting the output, information can be transmitted between the microprocessors.

  The servo CPU 11 is connected to a ROM 12 that stores a control program dedicated to servo control that executes processing of a position loop, a speed loop, and a current loop, and a RAM 13 that is used for temporary storage of data. The servo CPU 11 is connected to a pressure sensor 28 that detects an injection pressure provided on the injection molding machine main body via an A / D (analog / digital) converter (not shown). Further, the servo CPU 27 is connected to a servo amplifier 27 for driving an injection and screw rotation servomotor 29 connected to the injection shaft and the screw rotation shaft based on a command from the servo CPU 11. A position / speed detector 30 is attached to the servo motor 29, and an output signal from the position / speed detector 30 is fed back to the servo CPU 11.

  A ROM 18 storing a sequence program for controlling the sequence operation of the injection molding machine and a RAM 19 used for temporary storage of calculation data are connected to the PMC CPU 17, and an automatic operation program for overall control of the injection molding machine is connected to the CNC CPU 20. Are connected to a ROM 21 that stores data and the like, and a RAM 22 that is used for temporary storage of calculation data. The molding data storage RAM 23 formed of a non-volatile memory is a molding data storage memory for storing molding conditions relating to injection molding work, various set values, parameters, macro variables, and the like. A manual input device with LCD (LCD / MDI) 25 is connected to the bus 16 via an LCD display circuit 24, and is provided with numeric keys for inputting numeric data and various function keys, and is used to select a graph display screen and a function menu. In addition, various data input operations can be performed.

  The PMC CPU 17 controls opening / closing of the relays 8, 9A, 9B via the input / output interface 14, thereby detecting the set temperature and temperature detection for each of the heaters 4, 5A, 5B mounted in the heating zones of the nozzle 1 and the injection cylinder 2. PID control or the like is performed based on the detected temperature detected by the unit, and each heating zone can be controlled on / off to control the set temperature. In the on state, the heater is energized, and in the off state, the heater is deenergized. The temperature detection signals output from the temperature detectors 6, 7A, 7B arranged in the nozzle 1 and the injection cylinder 2 of the injection molding machine are voltage-frequency converted by the voltage frequency converter 15, and the converted signals are input / output interfaces. 14 and sent to the PMC CPU 17. The input / output interface 14 is an interface for receiving temperature detection signals from the temperature detection units 6, 7 </ b> A, 7 </ b> B.

  With the above configuration, the PMC CPU 17 controls the sequence operation including the temperature control of the entire injection molding machine, and the CNC CPU 20 controls each servo motor based on the operating program of the ROM 21 and the molding conditions stored in the molding data storage RAM 23. Based on the movement command distributed to each axis and the position and speed feedback signals detected by the position / velocity detector 30, the servo CPU 11 performs position loop control as in the prior art. Servo control such as speed loop control and current loop control is performed, so-called digital servo processing is executed, and the servo motor 29 is driven and controlled. The main power supply is connected to the heaters 4, 5A, 5B via the relays 8, 9A, 9B, and is also connected to the control device 10 and the servo amplifier 27. The voltage measuring device 31 measures the voltage of the main power source supplied to the heaters 4, 5A, 5B, the control device 10, and the servo amplifier 27 connected via the relays 8, 9A, 9B at a predetermined sampling period. . The voltage data of the main power source measured by the voltage measuring device 31 is sent to the PMCCPU 17 via the input / output interface 14.

  In the embodiment shown in FIG. 1, the power consumption can be accurately obtained using the above (Formula 1) to (Formula 3) without a means for measuring current (current measurement unit). The resistance values (R) of the heaters 4, 5A, 5B in the specifications are stored in advance in a memory (for example, a molding data storage RAM 23) on the injection molding machine for each zone of the heaters 4, 5A, 5B. Alternatively, the rated voltage (Vr) and the heater power (Wr) on the specifications at the rated voltage Vr are stored in advance in the memory of the injection molding machine (for example, the molding data storage RAM 23) for each zone of the heaters 4, 5A, 5B. Keep it. Accordingly, the injection molding machine shown in FIG. 1 has a heater power measuring function. Thus, as described above, the power consumption (Wt) of the heaters 4, 5A, 5B can be measured only by measuring the measured energization time ratio (H) of the heaters 4, 5A, 5B and the measured main power supply voltage (Vt). ). The ratio (H) of the energization time of the heaters 4, 5A, 5B can be obtained by measuring the time during which the heaters 4, 5A, 5B are energized within the period for each sampling period. For example, when the voltage of the main power source is sampled every second for 1 minute, energized for 30 seconds, and not energized for 30 seconds, the energization time ratio (H) is 50%.

  FIG. 2 is a diagram illustrating an embodiment using a servo amplifier provided with a voltage measuring unit. Here, differences from FIG. 1 will be described, and descriptions of the same configurations and functions will be omitted. Here, when the servo amplifier 27 has a voltage measurement unit (not shown), the voltage measured by the servo amplifier 27 may be used as it is by measuring the voltage at a predetermined sampling period. In this case, power can be measured by transferring the voltage measured by the servo amplifier 27 to the PMCCPU 17 via the bus 16 of the control device 10. Alternatively, the voltage data measured by the voltage measurement unit of the servo amplifier 27 is written into a memory (not shown) that can be referred to by the PMCCPU 17 constituting the heater power measurement unit, and the voltage data measured by the PMCCPU 17 is read and consumed. Electric power may be obtained. The voltage measuring unit of the servo amplifier 27 may measure the AC voltage supplied to the servo amplifier 27 and use it as it is, or measure the voltage after being converted from AC to DC in the servo amplifier 27. The measured DC voltage may be converted into an AC voltage supplied to the servo amplifier.

DESCRIPTION OF SYMBOLS 1 Nozzle 2 Injection cylinder 3 Screw 4 Heater 5A Heater 5B Heater 6 Temperature detection part 7A Temperature detection part 7B Temperature detection part 8 Relay 9A Relay 9B Relay 10 Control apparatus 11 Servo CPU
12 ROM
13 RAM
14 I / O interface 15 Voltage frequency converter 16 Bus 17 PMCCPU
18 ROM
19 RAM
20 CNCCPU
21 ROM
22 RAM
23 Molding data storage RAM
24 LCD display circuit 25 LCD / MDI

27 Servo Amplifier 28 Pressure Sensor 29 Servo Motor 30 Position / Speed Detector 31 Voltage Measuring Device

Claims (2)

A heater power measuring device for an injection molding machine having a heater,
The heater power measuring device includes:
A resistance value storage unit for storing a resistance value on the specification of the heater;
A voltage measuring unit for measuring a voltage supplied to the heater;
An energization time ratio measuring unit that measures a ratio of energization time during which the heater is energized within a predetermined period, and the voltage measurement unit measures voltage supplied to a servo amplifier on the injection molding machine. a part, the heater power measuring device for an injection molding machine and obtaining the power consumption of the heater from the resistance value and the measured voltage and the ratio of the measured heater energizing time. A heater power measuring device for an injection molding machine having a heater,
The heater power measuring device includes:
A rated voltage storage unit for storing the rated voltage of the heater;
A heater power storage unit for storing heater power at the rated voltage;
A voltage measuring unit for measuring a voltage supplied to the heater;
An energization time ratio measuring unit that measures a ratio of energization time during which the heater is energized within a predetermined period, and the voltage measurement unit measures voltage supplied to a servo amplifier on the injection molding machine. a part, the heater power of the injection molding machine and obtaining the power consumption of the heater from the voltage that is the measurement and heater power at the rated voltage and the rated voltage and proportion of the measured heater energizing time measuring device.

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