JP2011230309A - Apparatus and method for calculation of power consumption for injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate power consumption according to a molding condition.SOLUTION: An apparatus for calculation of power consumption (26, 35) for an injection molding machine includes: an input unit 35 that inputs the molding condition; a memory unit 262 that stores an approximate expression to calculate the power consumption when the injection molding machine is operated by the molding condition which is input to the input unit; and a power consumption calculation unit 261 that calculates the power consumption of the injection molding machine from the approximate expression stored in the memory unit based on the molding condition which is input to the input unit.

Description

  The present invention relates to a power consumption calculation device and a power consumption calculation method for an injection molding machine.

  Injection molding in an injection molding machine typically involves a mold closing process for closing a mold, a mold clamping process for clamping a mold, a nozzle touch process for pressing a nozzle against a mold sprue, and a screw in a cylinder. Injecting the molten material collected in front of the screw into the mold cavity, then holding the pressure for a while to suppress the generation of bubbles and sink marks, and filling the mold cavity A plasticizing / metering process in which the screw is rotated for the next cycle during the time between the cooled molten material being cooled and solidified, and the resin is melted and accumulated in front of the cylinder, and the solidified molded article In order to take out the mold from the mold, it comprises a mold opening process for opening the mold and a molded product projecting process in which the molded product is pushed out by a projecting pin provided on the mold.

  The electric power used in the electric injection molding machine includes electric power for heaters provided around the heating cylinder in order to melt the resin and electric power consumption of various electric motors. As motors incorporated in the electric injection molding machine, there are various electric motors such as an injection motor, a screw rotation motor, a mold opening / closing motor, and an ejector motor.

  Conventionally, in an injection molding machine control device that detects power consumption during operation and performs display related to the power consumption, detection means for detecting power consumption during operation and designation arbitrarily designated from the detected power consumption Ejection that includes power amount calculation means for determining the amount of power for the detection time, obtains predetermined conversion information (carbon dioxide emission information, electricity bill information, etc.) from the obtained power amount, and displays the conversion information together with the power amount A control device for a molding machine is known (for example, see Patent Document 1).

JP 2007-83432 A

  However, since actual molding conditions can be changed in various ways, actually measuring the amount of electric power for each of various molding conditions is a great effort and is not efficient.

  Accordingly, an object of the present invention is to provide a power consumption calculation device and a power consumption calculation method for an injection molding machine that can predict power consumption of the injection molding machine according to molding conditions.

In order to achieve the above object, according to one aspect of the present invention, a power consumption calculation apparatus for an injection molding machine,
An input means for inputting molding conditions;
Storage means for storing an approximate expression for calculating power consumption when the injection molding machine is operated under the molding conditions input to the input means;
A power consumption calculation device comprising: power consumption calculation means for calculating power consumption of the injection molding machine from the approximate expression stored in the storage means based on molding conditions input to the input means. Is provided.

According to another aspect of the present invention, a power consumption calculation method for an injection molding machine,
An input step for inputting molding conditions;
A step of reading out an approximate expression for calculating power consumption when the injection molding machine is operated under the molding conditions input in the input step from a storage unit;
And a power consumption calculating step of calculating power consumption of the injection molding machine from the read approximate expression based on the molding condition input in the input step. .

  ADVANTAGE OF THE INVENTION According to this invention, the power consumption calculation apparatus and power consumption calculation method for injection molding machines which can estimate the power consumption of an injection molding machine according to molding conditions are obtained.

It is a figure which shows the principal part structure of an example of the injection molding machine 1 with which the power consumption calculation apparatus of one Example of this invention is applied. 3 is a functional block diagram illustrating main functional units related to a power consumption calculation function of a controller 26. FIG. 3 is a flowchart showing an example of a main process of a power consumption calculation method realized by a controller 26. 3 is a functional block diagram showing main functional parts related to an optimum molding condition calculation function of a controller 26. FIG. 4 is a flowchart showing a flow of an example of main processing of an optimum molding condition calculation method realized by a controller 26.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a main part of an example of an injection molding machine 1 to which a power consumption calculating apparatus according to an embodiment of the present invention is applied.

  The injection molding machine 1 is an electric injection molding machine in this example, and includes a servo motor 11 for injection. The rotation of the servo motor 11 for injection is transmitted to the ball screw 12. A nut 13 that moves forward and backward by the rotation of the ball screw 12 is fixed to a pressure plate 14. The pressure plate 14 is movable along guide bars 15 and 16 fixed to a base frame (not shown). The forward / backward movement of the pressure plate 14 is transmitted to the screw 20 via the bearing 17, the load cell 18, and the injection shaft 19. The screw 20 is disposed in the heating cylinder 21 so as to be rotatable and movable in the axial direction. A hopper 22 for resin supply is provided at the rear portion of the screw 20 in the heating cylinder 21. Rotational motion of a screw rotating servomotor 24 is transmitted to the injection shaft 19 via a connecting member 23 such as a belt or a pulley. That is, the screw 20 is rotated when the injection shaft 19 is rotationally driven by the servo motor 24 for screw rotation.

  In the plasticizing / metering step, the molten resin is stored in the front portion of the screw 20, that is, the nozzle 21-1 side of the heating cylinder 21 by the screw 20 moving backward in the heating cylinder 21. In the injection process, molding is performed by filling the mold with molten resin stored in front of the screw 20 and pressurizing it. At this time, the force pushing the resin is detected by the load cell 18 as a reaction force. That is, the resin pressure at the front part of the screw is detected. The detected pressure is amplified by the load cell amplifier 25 and input to the controller 26 (control device) functioning as control means. In the pressure holding step, the resin filled in the mold is maintained at a predetermined pressure.

  A position detector 27 for detecting the amount of movement of the screw 20 is attached to the pressure plate 14. The detection signal of the position detector 27 is amplified by the amplifier 28 and input to the controller 26. This detection signal may also be used to detect the moving speed of the screw 20.

  The servo motors 11 and 24 are provided with encoders 31 and 32 for detecting the rotation speed, respectively. The rotation speeds detected by the encoders 31 and 32 are respectively input to the controller 26.

  The servo motor 42 is a servo motor for opening and closing the mold, and the servo motor 44 is a servo motor for projecting a molded product (ejector). The servo motor 42 drives a toggle link (not shown), for example, and realizes mold opening / closing. Moreover, the servo motor 44 implement | achieves molded article protrusion by moving an ejector rod (not shown) via a ball screw mechanism, for example. The servo motors 42 and 44 are provided with encoders 43 and 45 for detecting the rotational speed, respectively. The rotation speeds detected by the encoders 43 and 45 are respectively input to the controller 26.

  The controller 26 is mainly composed of a microcomputer, and includes, for example, a CPU, a ROM for storing control programs, a readable / writable RAM for storing calculation results, a timer, a counter, an input interface, an output interface, and the like. Have.

  The controller 26 sends current (torque) commands corresponding to a plurality of processes to the servo motors 11, 24, 42, 44. For example, the controller 26 controls the rotation speed of the servo motor 24 to realize the plasticizing / metering process. Further, the controller 26 controls the rotation speed of the servo motor 11 to realize the injection process and the pressure holding process. Similarly, the controller 26 controls the rotational speed of the servo motor 42 to realize the mold opening process and the mold closing process. The controller 26 controls the number of rotations of the servo motor 44 to realize a molded product protruding process.

  The user interface 35 includes an input setting unit capable of setting molding conditions for each molding process such as a mold opening / closing process and an injection process. In addition, the user interface 35 includes an input unit for inputting molding conditions for each molding process such as a mold opening / closing process and an injection process in order to calculate power consumption described later. In addition, the user interface 35 includes an input unit that inputs various instructions from the user, and an output unit (for example, a display unit) that outputs various information to the user.

  Typically, one cycle of injection molding in the injection molding machine 1 typically includes a mold closing process for closing the mold, a mold clamping process for clamping the mold, and a nozzle (not shown) in the mold sprue (not shown). Nozzle touching process, pressing the screw 20 in the heating cylinder 21 forward, and injecting the molten material accumulated in front of the screw 20 into a mold cavity (not shown); The screw 20 is rotated for the next cycle in the time between the pressure-holding process in which the holding pressure is applied for a while to suppress the generation of the molten metal and the molten material filled in the mold cavity is cooled and solidified. Then, a plasticizing / metering step for accumulating the resin in the front of the heating cylinder 21 while melting the resin, a mold opening step for opening the mold in order to take out the solidified molded product, and a molded product are provided in the mold. Et And projecting pins made of a molded article ejection step of extruding the (not shown).

  In the present embodiment, the controller 26 has a power consumption calculation function for predictively calculating power consumption generated by the operation of the injection molding machine 1.

  FIG. 2 is a functional block diagram showing main functional units related to the power consumption calculation function of the controller 26.

  The controller 26 includes a power consumption calculation unit 261 and an approximate expression storage unit 262. The power consumption calculation unit 261 is realized by the CPU of the controller 26 calculating an approximate expression stored in the approximate expression storage unit 262 using the input molding condition as an input parameter. The approximate expression storage unit 262 may be realized by the ROM of the controller 26.

  The power consumption calculation unit 261 calculates the approximate expression stored in the approximate expression storage unit 262 by using the molding condition input via the user interface 35 as an input parameter, thereby generating consumption caused by the operation of the injection molding machine 1. Calculate power predictively.

  Here, an example of the approximate expression stored in the approximate expression storage unit 262 will be described.

First, parameters (input parameters) for molding conditions are as follows, for example.
T: cycle time T _M-OC : mold opening / closing time T _ME : weighing time T _CA : mold clamping time F _CA : mold clamping force S _M-OC : mold opening / closing stroke V _M-OC : mold opening / closing speed S _S : filling amount V _S : Injection speed V _ME : Rotational speed of screw 20 during metering P _HP : Holding pressure T _HP : Holding pressure time Power consumption W _M-OC of the mold opening and closing process is calculated using the following approximate expression.
W _M-OC = a1 · S _M-OC + a2 · V _M-OC + a0
Here, a1, a2, and a0 are predetermined coefficients, and may be adapted by multiple regression analysis. Therefore, the motor power consumption W ₁ of the servo motor 42 of the mold opening and closing steps in one cycle is calculated as follows.
W ₁ = W _M-OC × T _M-OC / T
Power W _S of the injection step is calculated using the following approximate expression.
W _S = b1 · S _S + b2 · V _S + b0
Here, b1, b2, and b0 are predetermined coefficients, and may be adapted by multiple regression analysis. Therefore, the motor power consumption W ₂ of the servo motor 11 of the injection step in one cycle is calculated as follows.
W ₂ = W _S × (S _S / V _S ) / T
The motor power consumption W _{ME in the} weighing process is calculated using the following approximate expression.
W _ME = c1 · V _ME + c2
Here, c1 and c2 are predetermined coefficients, and may be adapted by the least square method. Therefore, the motor power consumption W ₃ of the servo motor 24 of the metering process in one cycle is calculated as follows.
W ₃ = W _ME × T _ME / T
The power consumption W _CA of the mold clamping process is calculated using the following approximate expression.
W _CA = d1 · F _CA + d2 · T _CA + d3
Here, d1, d2, and d3 are predetermined coefficients, and may be adapted by multiple regression analysis. Therefore, the mold clamping motor power consumption W ₄ steps in one cycle is calculated as follows.
W ₄ = W _CA × T _CA / T
Power W _H of the pressure holding process is calculated by using the following approximate expression.
W _HP = e1 · P _HP + e2 · T _HP + e3
Here, e1, e2, e3 are predetermined coefficients, and may be adapted by multiple regression analysis. Therefore, the motor power consumption W ₅ of the servo motor 11 of the pressure holding process in one cycle is calculated as follows.
W ₅ = W _HP × T _HP / T
The heater power _WH-ME in the metering process is calculated using the following approximate expression.
^{_{W H-ME = f1 · V}} ME 2 + f2 · V ME + f3
Here, f1, f2, and f3 are predetermined coefficients, and may be adapted by a least square method. Therefore, the heater power consumption power W ₆ in the weighing process in one cycle is calculated as follows.
W ₆ = W _H-ME × T _ME / T
The power consumption calculation unit 261 calculates the total power consumption W _Total in one cycle as follows by substituting the parameters of the molding conditions into the above approximate expressions.
W _Total = W ₁ + W ₂ + W ₃ + W ₄ + W ₅ + W ₆ + W ₇ + W ₈
Here, W ₇ represents the standby power of the motor in one cycle, and a measured value may be used. W ₈ represents the heater standby power in the weighing process in one cycle, and may be calculated as W ₈ = W _H × T _ME / T using the heater standby power W _H (measured value).

  FIG. 3 is a flowchart showing a flow of an example of main processing of the power consumption calculation method realized by the controller 26.

  In step 300, parameters of molding conditions (cycle time, mold opening / closing time, weighing time, etc.) input by the user via the user interface 35 are input.

  In step 302, the approximate expression stored in the approximate expression storage unit 262 is read.

In step 304, the power consumption calculation unit 261 calculates the approximate expression read in step 302 by using the molding conditions input in step 300 as an input parameter, so that the power consumption W ₁ and W _{2 of} each molding process is calculated. , W ₃ , W ₄ , W _{5 and the} like are calculated in a predictive manner, and the total power consumption W _Total is calculated.

In step 306, the calculation result of the power consumption calculated in step 304 is output via the user interface 35. At this time, the calculation results of the power consumption W ₁ , W ₂ , W ₃ , W ₄ , W _5, etc. of each molding process may be displayed individually, and the calculation result of the total power consumption W _Total may be displayed. Thereby, the user can grasp | ascertain the power consumption at the time of shape | molding on the input shaping conditions. Therefore, the user may review this calculation result and review the molding conditions again and input again, for example. In this case, the user can grasp what kind of power consumption is required under new molding conditions. In this way, the user can adjust the molding conditions in consideration of power consumption in advance.

  In the present embodiment, the controller 26 may further include an optimum molding condition calculation function for calculating an optimum molding condition in consideration of power consumption.

  FIG. 4 is a functional block diagram showing main functional units related to the optimum molding condition calculation function of the controller 26.

  The controller 26 includes an optimum molding condition calculation unit 263 and an approximate expression storage unit 262. The optimum molding condition calculation unit 263 is an optimum molding in which the power of the controller 26 calculated by the approximate expression stored in the approximate expression storage unit 262 satisfies a predetermined condition under the input constraint conditions. This is realized by calculating the conditions. The approximate expression storage unit 262 may be realized by the ROM of the controller 26.

  FIG. 5 is a flowchart showing a flow of an example of main processing of the optimum molding condition calculation method realized by the controller 26.

  In step 500, the constraint condition input by the user via the user interface 35 is input. The constraint condition may be, for example, a range (upper limit value and / or lower limit value) that can be changed with respect to parameters (cycle time, mold opening / closing time, weighing time, etc.) of the molding condition. For example, the cycle time may be an allowable range for the molding conditions, such as a range from T1 to T2, and a mold opening / closing time may be a range from T3 to T4. These changeable ranges may correspond to good product conditions. That is, the range in which the molding condition can be changed may be set within a range that satisfies the non-defective product condition. Further, the constraint condition may include a target value of power consumption or a target value of total power consumption in each molding process.

  In step 502, the approximate expression stored in the approximate expression storage unit 262 is read.

  In step 504, the optimum molding condition is calculated so that the power consumption calculated by the approximate expression read in step 502 is the minimum value by the optimum molding condition calculation unit 263 under the constraint condition input in step 500. Explore. In step 500, when the target value of power consumption is included in the constraint condition, the approximate expression read out in step 502 under the constraint condition input in step 500 by the optimum molding condition calculation unit 263. The optimum molding condition is searched for such that the power consumption calculated by the step is less than or equal to the target value. In this case, the optimum molding condition may be searched for within the range of the optimum molding condition.

In step 506, the calculation result of the optimum molding condition calculated in step 504 is output via the user interface 35. At this time, the calculation results of the power consumption W ₁ , W ₂ , W ₃ , W ₄ , W _5, etc. of each molding process under the optimum molding conditions are individually displayed, and the calculation result of the total power consumption W _Total is displayed. May be. Thereby, the user can grasp | ascertain the optimal molding conditions, and can grasp | ascertain the power consumption at the time of shape | molding on the said optimal molding conditions.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, the power consumption calculation function, the optimum molding condition calculation function, and the calculation result output function are realized by the controller 26 of the injection molding machine 1, but the power consumption calculation function and / or the optimum molding condition calculation function And / or the calculation result output function may be realized by an external computer (for example, a personal computer). In this case, the external computer may include a power consumption calculation function and / or an optimum molding condition calculation function corresponding to a plurality of types of injection molding machines.

  Further, in the above-described embodiment, the power consumption of the other molding process is calculated with the same approximate expression, such as calculating the power consumption of the servo motor 44 in the molded product protruding process with the same approximate expression. It is also possible to add.

  In the above-described embodiment, the power consumption is calculated for each molding process. However, the power consumption can be calculated by an approximate expression for each motor (servo motors 11, 24, 42, 44, etc.) or for each heater. It is. Further, in the above-described embodiment, the power consumption is calculated for each molding process and the total power consumption of one cycle is predicted. However, for one specific molding process or a combination of a plurality of specific molding processes. It is also possible to predict power consumption or total power consumption. Similarly, it is also possible to predict the power consumption or the total power consumption for a specific motor or a combination of a plurality of specific motors. Similarly, it is also possible to predict the power consumption or the total power consumption of a specific heater or a specific combination of a plurality of heaters.

  Also, if the power consumption of the unit with the highest power consumption among the power consumption calculated for each unit (each molding process, each motor, each heater) is changed (within the range of non-defective products) Thus, power consumption can be reduced efficiently.

DESCRIPTION OF SYMBOLS 1 Injection molding machine 11 Servo motor 12 Ball screw 13 Nut 14 Pressure plate 15, 16 Guide bar 17 Bearing 18 Load cell 19 Injection shaft 20 Screw 21 Heating cylinder 22 Hopper 23 Connecting member 24 Servo motor 26 Controller 27 Position detector 28 Amplifiers 31, 32 Encoder 35 User interface 42 Servo motor 44 Servo motors 43 and 45 Encoder 261 Power consumption calculation unit 262 Approximate expression storage unit 263 Optimal molding condition calculation unit

Claims (5)

A power consumption calculation device for an injection molding machine,
An input means for inputting molding conditions;
Storage means for storing an approximate expression for calculating power consumption when the injection molding machine is operated under the molding conditions input to the input means;
A power consumption calculation device comprising: power consumption calculation means for calculating power consumption of the injection molding machine from the approximate expression stored in the storage means based on molding conditions input to the input means. .   Optimal molding condition calculation means for calculating a molding condition such that the power consumption is a predetermined value or a minimum under the constraint that the molded article satisfies a predetermined good product condition based on the approximate expression stored in the storage means. The power consumption calculation device according to claim 1, further comprising:   The power consumption calculation apparatus according to claim 1, further comprising output means for outputting the power consumption calculated by the power consumption calculation means.   The power consumption calculation apparatus according to claim 1, which is incorporated in an injection molding machine or incorporated in an external computer independent of the injection molding machine. A power consumption calculation method for an injection molding machine,
An input step for inputting molding conditions;
A step of reading out an approximate expression for calculating power consumption when the injection molding machine is operated under the molding conditions input in the input step from a storage unit;
A power consumption calculation method comprising: a power consumption calculation step of calculating power consumption of the injection molding machine from the read approximate expression based on the molding condition input in the input step.

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