JP2011138463A - Numerical control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a numerical control device, which allows evaluation of energy consumption of a machine tool by machine driving energy derived from the machine and machining energy derived from machining. <P>SOLUTION: The numerical control device 1 for numerically controlling the machine tool 2 for machining a workpiece 4 by driving a power consuming element includes: an energy calculation unit 12 for calculating energy consumption by the operation of the machine tool 2. The energy calculation unit 12 calculates the energy consumption as the processing energy consumed according to the machining to the workpiece 4 by subtracting the machine energy consumption consumed according to the drive of the power consuming element from the total amount of energy consumption. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a numerical control device for numerical control of a machine tool.

  2. Description of the Related Art Conventionally, a numerical control device having a function of calculating power consumption and monitoring by screen display has been proposed in order to effectively use power and reduce power consumption in machining. For example, Patent Document 1 proposes a method of displaying power usage efficiency, which is a ratio of the integrated power amount in the power consumption element and the integrated power consumption during actual operation. Patent Document 2 proposes a power consumption display device that obtains and displays power consumption per cycle when the same operation cycle is repeatedly performed.

Japanese Patent Laid-Open No. 2002-243776 Japanese Patent No. 3088403

  The energy required for machining with a machine tool includes machine drive energy derived from the machine consumed by driving the motor of the machine device, and machining energy derived from machining consumed by machining such as cutting with a cutting tool. It is. Of these, the machining energy varies according to various conditions such as the material of the workpiece and the machining speed. The machine drive energy further includes energy that is consumed by the operation of the movable part of the machine tool, and energy that is consumed constantly while the power is turned on. As described above, there are various elements that consume energy in the machine tool, and measures for reducing energy consumption vary greatly depending on the consumption elements. In order to effectively reduce energy consumption, it is desirable that the breakdown of energy consumption can be grasped to some extent and that each can be evaluated.

  In the case of the prior art, the power consumption of the entire machine tool is calculated and displayed in a lump. Therefore, in order to know the breakdown of the energy consumption, a measuring means for each consumption element is separately used. For example, in order to measure the machining energy of cutting, a measuring means such as a cutting dynamometer is used between a tool and a machine tool or between a workpiece and a machine tool.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a numerical control device that can evaluate the energy consumption of a machine tool by machine drive energy derived from the machine and machining energy derived from the machining.

  In order to solve the above-described problems and achieve the object, the present invention is a numerical control device for numerically controlling a machine tool that drives a power consuming element to process a workpiece, Energy calculating means for calculating energy consumption due to operation, wherein the energy calculating means subtracts the machine energy consumption that is consumed when the power consumption element is driven from the total amount of energy consumption; It is characterized in that it is calculated as processing energy consumed in connection with the processing.

  According to the present invention, it is possible to evaluate the energy consumption of a machine tool based on the machine drive energy and the machining energy.

FIG. 1 is a diagram showing a block configuration of a numerical control device and a machine tool according to Embodiment 1 of the present invention. FIG. 2 is a flowchart showing a calculation procedure in the energy calculation unit. FIG. 3 is a diagram illustrating a display example of energy consumption (power consumption) by the energy display unit. FIG. 4 is a diagram illustrating a display example of time-series data according to the second embodiment. FIG. 5 is a flowchart showing a procedure for generating time-series data by calculation in the energy calculation unit. FIG. 6 is a diagram illustrating a display example of the relationship between the machining energy and the machining conditions. FIG. 7 is a diagram illustrating an example of transition of machining energy due to machining with a specific tool. FIG. 8 is a diagram for explaining calculation of energy consumption in the fourth embodiment. FIG. 9 is a flowchart showing a procedure for calculating energy consumption by the energy calculation unit.

  Embodiments of a numerical controller according to the present invention will be described below in detail with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a numerical controller 1 and a machine tool 2 according to Embodiment 1 of the present invention. In the figure, solid arrows indicate power supply paths, and broken arrows indicate signal transmission paths. The numerical control device 1 numerically controls the machine tool 2. The machine tool 2 processes the workpiece 4 into a desired shape by relative movement between the rotating tool 3 and the workpiece (workpiece) 4 installed on the work table. The tool 3 rotates by driving a spindle motor incorporated in the spindle head 5. The relative movement between the tool 3 and the workpiece 4 is realized by controlling a plurality of servo motors attached to a plurality of movable shafts (not shown).

  The spindle motor drive unit 6 drives the spindle motor. The servo motor drive unit 7 drives the servo motor. In addition, as a configuration example of a general movable shaft, for example, a linear motor that combines a rotary motor and a ball screw, a linear motor, a rotary shaft that combines a servo motor and a worm gear, a direct drive The thing by a motor is mentioned.

  In the present embodiment, the movable portion includes a portion of the power consuming element that is operated to move the tool 3 and the workpiece 4 relative to each other, such as a spindle motor, a servo motor, and an arm. Peripheral device unit 8 includes power consumption elements other than the movable unit, for example, a cooling device for cooling the spindle motor, a compressor for generating hydraulic pressure, an ATC (Automatic Tool Changer) device for exchanging the tool 3, and chips. Includes chip conveyor to be discharged. The numerical controller 1, the spindle motor drive unit 6, and the servo motor drive unit 7 are also included in the power consumption element. Electric power P is supplied from the factory power source to the numerical controller 1, the spindle motor drive unit 6, the servo motor drive unit 7 and the peripheral device unit 8 through a power conversion unit 9 including a transformer and a converter.

  The power conversion unit 9 outputs a power supply signal S3 indicating a power supply state. For example, when the power conversion unit 9 includes a power measurement unit and a power calculation function, a power supply signal S3 representing the amount of power is employed. Further, as the power supply signal S3, a combination of parameters used for calculating the electric energy, for example, a current and voltage, a torque and a rotation speed may be transmitted.

  The numerical control device 1 includes an NC control unit 11, an energy calculation unit (energy calculation unit) 12, and an energy display unit (display unit) 13. The NC control unit 11 analyzes the input motion command signal S0 and generates drive command signals S11 and S12 for the movable unit and an operation command signal S2 for the peripheral device unit 8. The motion command signal S0 is input by an operator via an NC program, a manual handle, or the like. The motion command is a command representing the motion of the tool 3 with respect to the workpiece 4 and the operation of the peripheral device unit 8.

  The drive command signals S11 and S12 are transmitted to the spindle motor drive unit 6 and the servo motor drive unit 7, respectively. The drive command is a command related to the position, angle, speed, and the like of each motor. The operation command signal S2 is transmitted to the peripheral device unit 8. The operation command is a command related to the operation of each element of the peripheral device unit 8. The drive command signals S11 and S12 and the operation command signal S2 are transmitted via a communication cable, for example.

  The spindle motor drive unit 6 applies a drive voltage V1 corresponding to the drive command signal S11 to the spindle motor. The spindle motor is controlled according to the drive command signal S11. The servo motor drive unit 7 applies a drive voltage V2 corresponding to the drive command signal S12 to the servo motor. The servo motor is controlled according to the drive command signal S12. The peripheral device unit 8 is controlled according to the operation command signal S2.

  Drive data D11 representing the drive state of the spindle motor is transmitted from the spindle motor drive unit 6 to the NC control unit 11. Drive data D12 representing the drive state of the servo motor is transmitted from the servo motor drive unit 7 to the NC control unit 11. As the driving state of the motor, for example, the position and angle of the motor, the rotation speed, the current, the voltage, the temperature and the efficiency are adopted. The operation data D2 representing the operation state of the peripheral device unit 8 is transmitted from the peripheral device unit 8 to the NC control unit 11. As the operation state of the device, for example, ON / OFF of a motor that moves the device, the number of rotations, temperature, pressure, current, voltage, and the like are employed. The drive data D11, D12 and the operation data D2 are transmitted via a communication cable, for example.

  The energy calculation unit 12 calculates energy consumption due to operation of the machine tool 2. The energy calculation unit 12 receives drive data D11 and D12 from the NC control unit 11, operation data D2, processing conditions, and a power signal corresponding to the power P from the power conversion unit 9. For example, as processing conditions in the cutting process, data relating to the type and identification number of the tool 3 used in the machine tool 2, the cutting speed, the feed speed, the cutting width and the cutting depth, and the like are used. The energy calculation unit 12 calculates machine consumption energy and machining energy based on all input data and signals, a plurality of combinations, or one. The energy display unit 13 functions as an output unit that outputs machine consumption energy and machining energy data calculated by the energy calculation unit 12 as a graphic display.

  The machining energy is assumed to be energy consumed in machining the workpiece 4 by the tool 3. For example, in the case of general cutting, the energy consumption corresponding to the shearing force acting between the tool and the workpiece, the frictional force generated on the tool flank and rake surface is mainly the material of the workpiece, It depends on various conditions such as cutting speed, cutting depth, and the presence or absence of cutting oil.

  The machine energy consumption is energy consumed as the power consuming element is driven. The machine consumption energy is divided into operation consumption energy consumed by performing a necessary operation of the movable part of the machine tool 2 and peripheral device consumption energy consumed by the peripheral device unit 8. The operating energy consumption is energy required to move a mechanical structure having a predetermined mass or inertia at a predetermined acceleration and speed for a predetermined distance. The energy consumed for operation includes energy required to exercise against disturbance factors such as friction and gravity.

FIG. 2 is a flowchart showing a calculation procedure in the energy calculation unit 12. In step S101, the total amount of energy consumed by the machine tool 2 during machining is calculated. For example, if the total power consumption measured by the power conversion unit 9 for the machine tool 2 is W _all [W], the total amount E _all [J] of energy consumption of the machine tool 2 is It is determined by the integration of the W _all.

Here, t1 is a measurement start time, and t2 is a measurement end time. For example, when energy consumption per product is measured, t1 corresponds to the processing start time for one product, and t2 corresponds to the processing end time. Further, when measuring the energy consumption while using a certain tool 3, t1 corresponds to the use start time of the tool 3, and t2 corresponds to the use end time. For example, when measuring the energy consumption per unit cutting distance L [m] in the cutting process, t1 and t2 that satisfy Expression (2) are set. When measuring energy consumption per unit cutting volume V [m ³ ], t1 and t2 satisfying Expression (3) are set.

(T2-t1) = L / F (2)
(T2−t1) = V / (D · H · F) (3)

  Here, F is a feed rate [m / s], D is a cut width [m], and H is a cut depth [m]. These parameters are included in the machining conditions transmitted from the NC control unit 11. Note that the cutting distance is a distance obtained by moving the tool 3 relative to the workpiece 4. The cutting volume is the volume of the part removed from the workpiece 4 by cutting using the tool 3.

  The energy consumption of the spindle motor can be calculated by several methods using the drive data D11 transmitted from the spindle motor drive unit 6 to the NC control unit 11. In the method described below, the energy consumption of the servomotor can be similarly calculated using the drive data D12 transmitted from the servomotor drive unit 7 to the NC control unit 11.

For example, when the motor current is two-phase converted, the voltages on the q-axis and d-axis of the motor are V _q and V _d [V], respectively, and the currents are I _q and I _d [A], respectively. As shown in the equation (4), the motor energy consumption E _m [J] can be calculated by obtaining electric power as the sum of products of the q-axis and d-axis currents and voltages and further integrating them. Thereby, the energy consumption of each motor is calculated | required.

  The total amount of energy consumed by the spindle motor and servo motor is the sum of the energy consumed for each motor according to equation (4). In general, it is known that the d-axis current and voltage are often smaller than the q-axis current and voltage, respectively. Even if the d-axis current and voltage are ignored, it can be said that the influence on the calculation result in this embodiment is small.

When the resistance R [Ω] of the motor armature and the inductances L _q and L _d [H] of the q axis and the d axis are included in the drive data D11 and D12, the equations (5-1) and (5-2) Thus, the voltages V _q and V _d may be calculated and substituted into the equation (4).

V _q = (R + pL _q ) I _q + ωL _d I _d + ωφ (5-1)
V _d = (R + pL _d ) I _d −ωL _q I _q (5-2)

  Here, p is a differential operator, ω is an electrical angular speed [rad / s], and φ is a motor magnetic flux [Wb]. These values are calculated by a known method from the induced voltage constant and the number of counter electrodes.

Also, if the approximate value of the motor efficiency η is known, the energy consumption E _m [J] of the motor is expressed by the torque T _m [Nm] and the rotational angular velocity ω _m [rad / The product of s] may be divided by the efficiency η to obtain electric power and further integrated. The torque T _m [Nm] is obtained as the product of the current I _q [A] and the torque constant K _t [Nm / A]. It is known that the efficiency η of a general motor is about 0.8 to 0.9.

In general, the output characteristics of a motor depend on the rotational speed. Further, in the drive command to the motor, the current is often expressed as a ratio [%] to the rated current of the motor. For example, when the relationship between the number of revolutions and the output is known, or for a motor given as a specification, the motor energy consumption E _m [J] is expressed by the rated output and the rated current as shown in Equation (7). The power may be obtained by dividing the product of the ratio of the current to η by η and further integrated. Here, W _m (ω _m ) [W] is a rated output that varies depending on the rotational angular velocity ω _m [rad / s]. I is a current [%] expressed as a ratio to the rated current in the drive command or feedback.

Generally, most of the servo motors have a known rated stall torque, and the characteristics are represented by the relationship between the rotational speed and the torque. In this case, the rated stall torque T _s [Nm] and the rotational angular velocity ω _m [rad / s] are used instead of the rated output of the formula (7), and the calculation can be performed as in the formula (8).

Peripheral device energy consumed by the peripheral device unit 8 may be measured by transmitting power to the NC control unit 11 when the entire peripheral device unit 8 is operated, and each motor for driving the peripheral device unit 8. May be calculated as the sum obtained by any one of formulas (4) to (8). For a device whose power consumption during operation can be considered constant or constant, the power consumption in the specification or the power consumption measured separately can be expressed as a constant W _p [W]. The energy consumption E _p [J] for the device may be calculated by integrating a constant W _p as shown in Equation (9).

Energy consumption in the peripheral portion 8, the power consumption E _all calculated from power measured by the power conversion unit 9, it may be obtained by subtracting the sum of the spindle motor and energy consumption E _m of the servo motors.

  In step S102, the energy calculation unit 12 calculates machine energy consumption. The machine energy consumption is energy consumption other than machining energy out of the total energy consumption of the machine tool 2, and thus corresponds to energy consumption when the machine tool 2 is operated without machining. For example, the energy consumption is obtained and stored based on the power consumption measured by the power conversion unit 9 during the trial operation of the machine tool 2 in the preparation stage of machining. Thereby, the machine consumption energy during processing can be accurately estimated.

The motor torque T _m [Nm] can be simply calculated by the equation (10). By using the rotational angular velocity ω _m [rad / s] included in the drive data D11 and D12, the torque T _m is obtained by the equation (10), and the rotational angular velocity ω _m and the torque T _m are substituted into the equation (6). The energy consumption of the motor can be calculated easily.
T _m = Jω _m + cω _m + f · sgn (ω _m ) + d (10)

Here, J is the motor shaft equivalent moment of inertia [kgm ² ], c is the motor shaft equivalent viscous friction coefficient [Nm / (rad / s)], and f is the motor shaft equivalent Coulomb friction torque [Nm]. sgn is a sign function, and is +1 when the rotational angular velocity ω _m is a positive value, -1 when it is a negative value, and zero when it is zero. d is a load torque [Nm] due to gravity, which acts on the vertical axis. In the case of a tilt table having an unbalanced mass, the value of the load torque d due to gravity changes according to the tilt angle. These values are different for each machine, but can be identified by a known method from, for example, a motor torque waveform during a sine wave reciprocating motion.

  Note that the motor torque, rotational angular velocity, current, or voltage may be estimated by applying a more detailed mathematical model that takes into account the motor's electrical circuit, control system, and mechanical vibration characteristics. As a result, the machine energy consumption can be estimated more accurately.

  In step S103, the energy calculation unit 12 calculates the machining energy by subtracting the machine energy consumption calculated in step S102 from the total energy consumption. The total energy consumption during machining corresponds to the sum of machine energy consumption and machining energy. For this reason, the difference between the total energy consumption and the machine energy consumption can be estimated as the machining energy. In step S104, the numerical controller 1 stores the machining energy calculated in step S103 and the machine consumption energy calculated in step S102.

  FIG. 3 is a diagram illustrating a display example of energy consumption by the energy display unit 13. Here, the energy consumption is indicated by the power consumption [Wh]. The energy display unit 13 displays the machining energy and machine energy consumption measured or estimated by the calculation in the energy calculation unit 12 and stored in the numerical control device 1 as a bar graph. The machine energy consumption is displayed separately for the operation energy consumed by the movable part and the peripheral device energy consumed by the peripheral device unit 8.

  The energy calculation unit 12 calculates processing energy, operation energy consumption, and peripheral device energy consumption for each processing step of the workpiece 4. The numerical control device 1 stores machining energy, operation energy consumption, and peripheral device consumption energy in association with the machining process. The energy display unit 13 displays processing energy, operation energy consumption, and peripheral device energy consumption for each processing step. Thereby, even if it does not use a cutting dynamometer etc., the energy consumption of the machine tool 2 can be evaluated about processing energy, operation | movement energy, and peripheral device consumption energy. This evaluation makes it possible to determine which of the processing conditions, the movable part, and the peripheral device part should be improved in order to reduce energy consumption. Further, the association with the machining process enables a clear determination of the machining process to be improved in order to reduce energy consumption.

  In this example, the energy display unit 13 displays “roughing”, “medium finishing”, and “finishing” processes. The vertical axis of the graph represents power consumption [Wh], and the horizontal axis represents each processing step. (T1), (T2), and (T3) displayed together with the names of the machining steps represent the identification numbers of the tools 3 used for each machining. Moreover, in this example, the total electric energy through each processing step is displayed together with each energy consumption for each processing step.

  In many processes by the machine tool 2, a plurality of different tools 3 are used for each process. By displaying the tool 3 used in conjunction with the machining process, it becomes possible to compare the machining energy every time the tool 3 is changed. As a result, it is possible to accurately determine the wear status of the tool 3 and the quality of the cutting conditions. In particular, for general-purpose machine tools used for machining a wide variety of workpieces such as machining centers and NC lathes, consumption of common machining processes (for example, drilling) widely used for various machining By accurately grasping energy, it is possible to effectively reduce energy consumption.

  The numerical control device 1 is not limited to the case where the machining energy, the operation energy consumption, and the peripheral device consumption energy are calculated and displayed for each machining process, and may be calculated and displayed for each unit time or unit machining amount. For example, in the case of cutting, the processing amount is expressed as a cutting distance or a cutting volume. This makes it possible to check the status of the tool 3 every time the machining time or machining amount increases.

  The display mode in the energy display unit 13 is not limited to the case described in the present embodiment, and the processing energy and the machine consumption energy may be indicated by a graph other than the bar graph, for example, a line graph. Further, the machining energy and the machine energy consumption may be displayed as numerical values such as power consumption. As the output means, in addition to using the energy display unit 13 having a screen for graphic display, for example, a printer or the like that executes output by printing may be used. Further, the output means may be a recording means for recording processing energy and machine consumption energy on a recording medium, or a communication means for communication. The numerical control apparatus 1 can be widely applied to any machine tool as long as it can be a target of numerical control.

Embodiment 2. FIG.
The numerical control device according to the second embodiment is characterized by comprising output means capable of outputting machining energy data per unit machining amount, per unit time, or for each machining process as time series data. Since the schematic configuration of the numerical control device is the same as that of the first embodiment, the configuration shown in FIG. 1 is used for the description, and description of portions other than the features of the present embodiment is omitted.

  FIG. 4 is a diagram illustrating a display example of time-series data according to the present embodiment. The energy display unit 13 displays the machining energy stored in the numerical controller 1 in association with the machining process using the specific tool 3 (in this example, “T1”) as a line graph. The vertical axis of the graph represents power consumption [Wh] per unit processing amount, and the horizontal axis represents time in an arbitrary unit.

  The energy display unit 13 displays the processing conditions when the power consumption is minimized (black circles in the figure) and the current (white triangles in the figure) together with the graph. . In this example, the feed speed F and the spindle motor rotation speed S are displayed as the machining conditions. Note that the display of the energy display unit 13 may be appropriately switched between the state of FIG. 3 described in the first embodiment and the state of FIG. 4 described in the present embodiment, and both are displayed simultaneously. It is also good.

  FIG. 5 is a flowchart showing a procedure for generating time-series data by calculation in the energy calculation unit 12. The procedure described here is performed, for example, every predetermined sampling period set as appropriate. In step S <b> 111, the energy calculation unit 12 determines whether or not the current processing meets a preset aggregation condition. For example, in the case of machining using a preselected tool 3 (“T1” in this example), it is determined that the total condition is met. In the case of machining using other tools 3, it is determined that the total condition is not met (No at Step S <b> 111), and data generation at that time is terminated.

  If it is determined that the total condition is met (step S111, Yes), the energy calculation unit 12 calculates the machining amount in step S112. For example, in the case of cutting, the processing amount is expressed as a cutting distance or a cutting volume. The calculated machining amount is accumulated until data at the next time is calculated in step S115 described later. In step S113, it is determined whether or not the machining amount calculated in step S112 exceeds a preset unit machining amount.

When it is determined that the machining amount exceeds the unit machining amount (step S113, Yes), in step S114, “1” is added to the variable k representing the time in the time-series data, so that the next time Go to the data. The variable k is a value corresponding to a time or a value corresponding to an index used for displaying time-series data. When the data is advanced to the next time, the processing amount is initialized in step S115. Subsequently, in step S116, initializing the energy consumption _{E k} at that time.

When it is determined that the machining amount does not exceed the unit machining amount (step S113, No), or when the consumed energy _Ek is initialized in step S116, the energy calculation unit 12 uses the power P in step S117. calculate. The power P is calculated using, for example, W _all shown on the right side of the above equation (1) or (V _q I _q + V _d I _d ) shown on the right side of the equation (4). Next, the energy calculating unit 12 calculates the consumption energy _{E k} by the power P integrating (accumulating) at step S118. Further, the energy calculation unit 12 extracts the machining energy from the total energy consumption in the same manner as the procedure shown in FIG.

  Suppose that the instantaneous value of energy required for machining and the power consumption per unit time are displayed. For example, if the rotation speed of the spindle motor is kept constant and the feed speed is increased, the machining load increases and the power consumption per hour increases. On the other hand, increasing the feed speed shortens the machining time. For this reason, it becomes difficult to grasp the machining energy required for the entire machining site.

  When displaying the machining energy per unit machining amount as in the present embodiment, the machining energy required for the whole machining is obtained by multiplying the machining energy per unit machining amount by the machining amount of the entire machining site. Is possible. The machining energy per unit machining amount and the machining energy required for machining the entire machining site are in a proportional relationship. If the machining energy per unit machining amount can be reduced, the machining energy of the entire machining site is also reduced.

  At the machining site, for example, by performing trial machining while changing machining conditions such as a feed speed and the number of rotations of the spindle motor using an override switch or the like, it is possible to search for a machining condition with the lowest energy consumption. Further, by displaying the machining conditions with the lowest energy consumption on the energy display unit 13, the searched machining conditions can be easily recognized. In this embodiment, instead of outputting machining energy per unit machining amount as time series data, machining energy per machining process or unit time may be outputted as time series data.

  As shown in FIG. 6, the relationship between machining energy consumed for machining a specific machining site (for example, removal shape or machining feature such as hole, groove, side surface, upper surface, etc.) and machining conditions is displayed. Also good. In the illustrated bar graph, the vertical axis represents power consumption [Wh] and the vertical axis represents each processing condition. By such a display, the relationship between the machining conditions and the consumed machining energy is further clarified, and the machining conditions can be easily adjusted.

  In the example shown in FIG. 6, not only processing energy but also operation energy consumption and peripheral device energy consumption are displayed together. By displaying the machine energy consumption together with the processing energy, it is possible to minimize the total energy consumption including both. Also in the display shown in FIG. 4, a graph of machine energy consumption may be displayed together with the machining energy. In FIGS. 4 and 6, the energy consumption obtained by adding the machining energy and the machine energy consumption may be displayed.

Embodiment 3 FIG.
The numerical control device according to the third embodiment is characterized by determining whether or not to replace the tool based on the transition of the machining energy for each tool. Since the schematic configuration of the numerical control device is the same as that of the first embodiment, the configuration shown in FIG. 1 is used for the description, and description of portions other than the features of the present embodiment is omitted.

  In general, when a large number of workpieces 4 are processed or for a long period of time, the wear of the tool 3 progresses, or damage such as chipping or breakage occurs as the number of processing and the processing time increase. Such a failure of the tool 3 causes a change such as a significant increase in machining energy and a reduction in machining energy due to a significant reduction in machining efficiency depending on the state such as chipping. Such a change in the machining state causes waste of energy consumption, a reduction in machining accuracy and machining quality, and therefore it is desirable to appropriately grasp the change before a serious abnormality occurs.

  In the present embodiment, the machining energy data calculated by the energy calculation unit 12 is stored in the numerical control device 1 and input to the NC control unit 11. The NC control unit 11 compares the machining energy in the specific tool 3 or machining process with a preset setting range. When the machining energy exceeds the set range or when there is a significant change in the machining energy, the NC control unit 11 determines that the tool 3 is to be replaced on the assumption that an abnormality has occurred in the tool 3. To do. In response to the tool change determination by the NC control unit 11, the machine tool 2 stops machining.

  The peripheral device unit 8 of the present embodiment includes a tool changer. When the NC control unit 11 determines to change the tool, the NC control unit 11 outputs a tool change command to the tool changer. The tool changer exchanges the tool 3 in accordance with a tool change command. As described above, the numerical controller 1 detects the transition of the machining energy by the NC control unit 11 and executes either continuation of machining by the tool 3 or replacement of the tool 3 based on the determination based on the transition. To do.

  FIG. 7 is a diagram illustrating an example of transition of machining energy due to machining with a specific tool 3. In this example, the transition of machining energy is represented by a bar graph with the horizontal axis representing unit time, the number of machining, the machining lot, and the like, and the horizontal axis representing power consumption [Wh]. As the processing using the specific tool 3 progresses, the processing energy generated by the processing increases. In this example, a significant increase in machining energy has been confirmed particularly at the last time point, and the possibility of a machining defect occurring after that point is high.

  In the present embodiment, a threshold value that serves as a guide for replacement is set in advance before the possibility of processing failure is high, and when the processing energy exceeds the threshold value (at the second bar graph from the right in the figure). Change the tool 3. As a result, it is possible to prevent the occurrence of processing defects and to suppress the consumption of energy consumption. In addition, the tool 3 can be replaced at an appropriate timing regardless of the user's experience, and an effect of suppressing wasteful replacement of the tool 3 that can be used continuously can be obtained. In addition, it is good also as setting the threshold value of the process energy used as the standard of replacement | exchange of the tool 3 not only an upper limit but a minimum. By setting the lower limit, it becomes possible to detect a change in the machining state due to a significant reduction in machining energy.

  The present embodiment is not limited to the case where the tool 3 is replaced by a tool replacement command based on the transition of machining energy. It suffices as long as it can stop the machining by the tool 3 based on the determination based on the transition of the machining energy for each tool. Also in this case, it is possible to prevent the occurrence of processing defects and to suppress the consumption of energy consumption. In this case, it is good also as notifying the stop of a process with an alarm simultaneously with the process stop with the said tool 3. FIG.

Embodiment 4 FIG.
The numerical control device according to the fourth embodiment is characterized in that it calculates total energy consumption during a period in which a machining program for automatic operation is selected. Since the schematic configuration of the numerical control device is the same as that of the first embodiment, the configuration shown in FIG. 1 is used for the description, and description of portions other than the features of the present embodiment is omitted.

  In preparation (setup) before processing a workpiece, energy consumption occurs when measuring the position of the workpiece by manual operation or exchanging the tool 3. After the workpiece is processed, energy is consumed in subsequent operations such as unloading the workpiece by manual operation, removing the tool 3, and cleaning. When the machine tool 2 is automatically operated, energy consumption occurs in, for example, input for setting the tool length and coordinate offset when the automatic operation mode is set. In addition, power consumption occurs when machining by automatic operation is finished and the apparatus enters a standby state. Thus, by calculating including the energy consumption during the period when machining on the workpiece is stopped, the energy consumption of the machine tool 2 can be grasped more accurately.

  FIG. 8 is a diagram for explaining calculation of energy consumption in the present embodiment. In the graph, the vertical axis represents power consumption [W], and the horizontal axis represents time in an arbitrary unit. In the present embodiment, the current energy consumption is distributed according to the machining program selected in the numerical controller 1 regardless of whether automatic operation is being performed or whether machining is being performed. In general, automatic operation of the machine tool 2 starts machining after selecting (searching) a machining program, confirming a tool or coordinate system used for machining, and setting a correction amount. In order to start the next processing after the end of the processing, the next processing program is selected, and the same confirmation and setting are performed.

  For example, it is assumed that machining programs O1, O2, and O3 for automatic operation are sequentially selected. Each period in which the machining programs O1, O2, and O3 are selected includes an automatic operation mode (first mode) period for automatic operation and a manual operation mode (second mode) period for manual operation. It is divided into. In the manual operation mode, post work and setup are performed in accordance with switching of the machining program. In the automatic operation mode, the machining of the workpiece is repeated. The period of the automatic operation mode includes a workpiece machining period corresponding to the number of workpieces to be machined.

  Here, it is assumed that three workpieces are machined by the machining program O2. The energy consumption during the period when the machining program O2 is selected is the sum of the energy consumption EM1 during the setup period of the manual operation mode, the energy consumption EA during the automatic operation mode period, and the energy consumption EM2 during the subsequent operation period of the manual operation mode. Is calculated. Of the period of the automatic operation mode, the period d from when the machining of the workpiece is finished to when the operation mode is switched to the manual operation mode is, for example, a period in which the worker is left in the automatic operation mode from the machining site It is.

The energy consumption per workpiece by the machining program O2 is the sum of the energy consumptions EM1, EA, EM2 in the manual operation mode and the automatic operation mode, as shown in the equation (11). It is obtained by dividing by N = 3).
(Energy consumption per workpiece) = (EM1 + EA + EM2) / N (11)

  In the present embodiment, the energy display unit 13 may be omitted. The machining condition transmitted from the NC control unit 11 to the energy calculation unit 12 includes the name or identification number of the machining program. The “machining program” in the present embodiment refers to a main program that uses machining for each workpiece as a unit. Even when the subprogram is read from the main program and executed, it is preferable that the selected machining program is defined so as to be identified by the main program.

FIG. 9 is a flowchart showing a procedure for calculating energy consumption by the energy calculation unit 12. In step S121, it is determined whether or not there is a change in the selected machining program. When there is a change in the selected machining program (step S121, Yes), in step S122, the energy consumption E _j corresponding to the machining program is initialized, for example, zero.

When there is no change in the selected machining program (step S121, No), or when the consumed energy E _j is initialized in step S122, the energy calculation unit 12 performs the same as in the above embodiment in step S123. To calculate the power P. Next, the energy calculation unit 12 calculates the consumed energy E _j by integrating (accumulating) the electric power P in step S124. Further, in step S125, the energy calculation unit 12 calculates the energy consumption per workpiece by dividing the energy consumption E _j by the number of machining N.

  Note that the energy consumption during the manual operation mode and the energy consumption during the period d from when the workpiece is processed to when the manual operation mode is switched occur regardless of the number N of workpieces. About the energy consumption of such a period, it can be considered that all the N works are equally allocated by the calculation shown in Expression (11).

  According to the present embodiment, not only the energy consumption during machining of the workpiece but also the energy consumption during the manual operation mode for set-up and post-work and the period during which machining is stopped in the automatic operation mode are included. Can be calculated. Thereby, it becomes possible to grasp | ascertain energy consumption correctly. In addition, energy consumption during the manual operation mode and energy consumption during the automatic operation mode and when machining is stopped can be automatically distributed for each selected machining program, and energy consumption data is collected. Can be reduced.

  As described above, the numerical control device according to the present invention is useful for effective use of electric power and reduction of power consumption in machining with a machine tool.

DESCRIPTION OF SYMBOLS 1 Numerical control apparatus 2 Machine tool 3 Tool 4 Work piece 6 Spindle motor drive part 7 Servo motor drive part 8 Peripheral equipment part 11 NC control part 12 Energy calculation part 13 Energy display part

Claims (10)

A numerical control device for numerically controlling a machine tool that drives a power consuming element to process a workpiece,
Energy calculating means for calculating energy consumption due to operation of the machine tool;
The energy calculation means calculates the machining energy consumed as a result of machining the workpiece by subtracting the machine energy consumed as the power consuming element is driven from the total amount of energy consumed. A numerical controller characterized by that.   The machine energy consumption is an operating energy consumed by a movable part for operating a tool for machining the workpiece in the machine tool, and a peripheral element that is the power consuming element other than the movable part in the machine tool. The numerical control apparatus according to claim 1, further comprising: peripheral device energy consumption consumed by the device unit.   The numerical control device according to claim 1, wherein the energy calculating unit calculates the machine energy consumption and the machining energy for each machining process of the workpiece. Numerically control a machine tool that processes the workpiece using a plurality of tools,
4. The apparatus according to claim 1, further comprising an output unit that outputs the machine consumption energy and the machining energy data calculated by the energy calculation unit separately for each tool. 5. Numerical control unit.   The numerical control apparatus according to claim 4, wherein the output unit outputs the processing energy data as time series data.   6. The numerical control apparatus according to claim 5, wherein the output means outputs the machining energy data as data for each unit machining amount obtained by machining the workpiece by the tool.   The numerical control apparatus according to claim 4, wherein the output unit includes a display unit that graphically displays the data of the machine energy consumption and the machining energy.   The numerical control apparatus according to claim 7, wherein the display unit displays at least the processing energy data for each processing condition.   9. The numerical control according to claim 1, wherein continuation and stop of machining by the tool are determined based on a transition of the machining energy for each tool machining the workpiece. apparatus. A numerical control device for numerically controlling a machine tool that drives a power consuming element to process a workpiece,
Energy calculating means for calculating energy consumption due to operation of the machine tool;
Of the period in which the machining program for automatic operation is selected, the energy consumption in the period of the first mode for automatic operation and the period of the second mode other than the period of the first mode A numerical control device that calculates the energy consumption in total.

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