Numerical control and device for detecting changes in location

Abstract

Numerical control (10) for use in a machine tool (40) having five or more axes, the numerical control (10) comprising: a first path control hardware (16) capable of performing path control for five or more axes on the machine tool (40); a second path control hardware (17) capable of performing path control for four or fewer axes on the machine tool (40); and a path control unit (111) for performing control such that the first path control hardware (16) does not function when a displacement of the numerical controller (10) is detected in a displacement detection device (20) capable of detecting a displacement of the numerical controller (10).

Description

Field of InterestThe present disclosure relates to a numerical controller having a location change prevention function.BackgroundSome machine tools employing numerical control may perform path control for five or more axes, while others may perform path control for four or less axes. Machine tools capable of performing path control for five or more axes can perform complicated processings, so that execution control becomes more and more severe. Therefore, machine tools capable of performing path control for five or more axes must each have a location change prevention function as a device for execution control. In JP 2018-147 346 A, a method is disclosed in which when a piezoelectric sensor detects vibration, a machine tool causes a power supply unit to supply power to a microprocessor (MPU), and a displacement detection device determines whether a displacement has occurred under the control of the MPU. In this way, the machine tool implements the location change protection function and also enables saving of electrical energy.Document JP 2011-145 804 A proposes to inhibit or restrict the operation of a machine tool when an unauthorized displacement has been detected. Document DE 196 54 712 B4 discloses a machine tool with five axes. The prior art also includes CN 1 06 919 139 A.Brief Description of the InventionTechnical Problem SettingHowever, the machine tool described in JP 2018-147 346 A has a problem that the location change prevention function may be disabled by modifying the hardware. Specifically, in the machine tool described in JP 2018-147 346 A, the MPU cannot receive from the displacement detection device the result of determining a relocation of the machine tool when a signal line between the piezoelectric sensor and a power supply integrated circuit (IC) and / or a signal line between the MPU and a second switch and / or a signal line between the displacement detection device and the MPU is disconnected. Accordingly, there is a possibility that a path control function for five or more axes, which is a function whose unauthorized use must be prevented, can be fraudulently used when the location change prevention function is deactivated.The present disclosure has been made in view of the above, and an object of the present disclosure is to provide a numerical controller in which deactivation of a location change prevention function due to hardware modification can be prevented.Solution of Problem SettingIn order to solve the above problem and achieve the object, a numerical controller according to the present disclosure includes the combination of the features of the independent claim or the independent claims. Preferred refinements are found in the dependent claims and the dependent claim.Advantageous Effects of the InventionThe numerical controller according to the present disclosure causes deactivation of a location change prevention function due to hardware modification to be prevented.Brief Description of the FiguresFIG. 1 is a diagram showing a configuration example of a numerical controller, a displacement detection device, and a display device according to the present embodiment. FIG. 2 is a flowchart illustrating operation of a numerical controller according to the present embodiment. FIG. 3 is a diagram showing an example of the hardware configuration of a numerical controller according to the present embodiment.DESCRIPTION OF EMBODIMENTSHereinafter, a numerical controller and a displacement detection device according to an embodiment of the present disclosure will be described in detail with reference to the figures.EmbodimentFIG. 1 is a diagram showing a configuration example of a numerical controller 10, a displacement detection device 20, and a display device 30 according to the present embodiment. The numerical controller 10 is connected to the displacement detection device 20, the display device 30, and a machine tool 40. The numerical controller 10 is a device to be used for the five-axis or more-axis machine tool 40. The displacement detection device 20 is an apparatus capable of detecting a displacement of the numerical controller 10 connected to the displacement detection device 20.First, the configuration of the numerical controller 10 will be described. As illustrated in FIG. 1, the numerical controller 10 includes a control unit 11, a power supply unit 12, storage devices 13 and 14, and an external interface (I / F) 15. the control unit 11 includes a trajectory control unit 111, a storage device interface power supply circuit 112, and storage device interfaces 113 and 114. In the numerical controller 10, the storage device interface 113 and the storage device 13 constitute five-axis or more-axis trajectory control hardware 16 capable of performing five-axis or more trajectory control on the machine tool 40. Further, the storage device interface 114 and the storage device 14 in the numerical controller 10 constitute four-axis or less trajectory control hardware 17 capable of performing four-axis or less trajectory control on the machine tool 40. The path control hardware 16 for five or more axes may be referred to as first path control hardware, and the path control hardware 17 for four or less axes may be referred to as second path control hardware.When the numerical controller 10 is in a turned-on state, the power supply unit 12 supplies power to the control unit 11 and the storage devices 13 and 14, and supplies power to the displacement detection device 20 via the external interface 15. The power supply unit 12 can supply each individual component with direct current supplied from an external power supply (not shown). Alternatively, the power supply unit 12 may receive AC power from an external power supply (not shown) or the like, generate DC power from the AC power, and supply the generated DC power to each individual component. When the numerical controller 10 is in a power-off state, the power supply unit 12 does not supply power to the control unit 11 and the storage devices 13 and 14, and also does not supply power to the displacement detection device 20 via the external interface 15.The storage device 13 is a first storage device that stores a program to be used when the numerical controller 10 on the machine tool 40 executes a control procedure for the path control function for five or more axes. The program used when the control procedure of the trajectory control function is executed for five or more axes is a first program.The storage device 14 is a second storage device that stores a program to be used when the numerical controller 10 on the machine tool 40 executes a control procedure for the path control function for four or less axes. The program used when the control procedure of the trajectory control function is executed for four or less axes is a second program.The external interface 15 is an interface that can connect the numerical controller 10 and the displacement detection device 20.The control unit 11 executes the control procedure in the numerical controller 10. When power is supplied from the power supply unit 12, the storage device interface power supply circuit 112 in the control unit 11 generates and supplies power to the storage device interfaces 113 and 114 under the control of the trajectory control unit 111. Under the control of the trajectory control unit 111, the storage device interface power supply circuit 112 supplies power to the storage device interfaces 113 and 114 when no change in location of the numerical controller 10 has been detected by the displacement detection device 20, and supplies power to only the storage device interface 114 when displacement of the numerical controller 10 has been detected by the displacement detection device 20.The storage device interface 113 is an interface that connects the control unit 11 and the storage device 13 to each other, so that the control unit 11 and the storage device 13 can communicate with each other. The storage device interface 113 is a first storage device interface that can perform reading and writing of a program stored in the storage device 13 under the control of the trajectory control unit 111.The storage device interface 114 is an interface that connects the control unit 11 and the storage device 14 to each other, so that the control unit 11 and the storage device 14 can communicate with each other. The storage device interface 114 is a second storage device interface that can perform reading and writing of a program stored in the storage device 14 under the control of the trajectory control unit 111.The trajectory control unit 111 controls the power supply from the storage device interface power supply circuit 112 to the storage device interface 113 on the basis of a protocol stored in a storage device 26 (described later) included in the displacement detection device 20. Specifically, the trajectory control unit 111 may determine that displacement of the numerical controller 10 has been detected by the displacement detection device 20 when a change-of-location occurrence log indicating that the numerical controller 10 has been displaced is stored in the storage device 26 included in the displacement detection device 20. When a relocation of the numerical controller 10 is detected by the relocation detection device 20, the trajectory control unit 111 interrupts the power supply from the storage device interface power supply circuit 112 to the storage device interface 113 and electrically interrupts the reading and writing to the storage device 13.Next, the configuration of the displacement detection device 20 will be described. As illustrated in FIG. 1, the displacement detection device 20 includes a power supply control circuit 21, an electronic switch 22, a sensor 23, an A / D converter (analog-to-digital converter) 24, a control unit 25, and the storage device 26. Note that the displacement detection device 20 and the numerical controller 10 may be configured such that the numerical controller 10 is equipped with the displacement detection device 20 provided as a separate unit, i.e., the displacement detection device 20 provided as a separate unit may be incorporated into the numerical controller 10.The sensor 23 is a sensor for detecting displacement of the numerical controller 10. As sensor 23, for example, an acceleration sensor and / or an angular velocity sensor and / or a vibration sensor are attached. The sensor 23 detects inertial changes occurring when the numerical controller 10 is displaced, such as inclination, movement, vibration, and shock. When a plurality of kinds of sensors are included as the sensor 23 in the displacement detection device 20, the accuracy of detecting a relocation of the numerical controller 10 can be improved and misdetections can be reduced.The A / D converter 24 is a converter that performs A / D conversion of an analog data detected by the sensor 23, that is, converts the detection value into a digital data.The control unit 25 compares the acquired digital data converted by the A / D converter 24 with a displacement determination threshold value of the numerical controller 10 stored in the storage device 26 in advance. When the detection value exceeds the threshold value, the control unit 25 determines that the numerical controller 10 has been displaced, and stores, in the storage device 26, a displacement occurrence log indicating that the numerical controller 10 has been displaced. In response to a request from the numerical controller 10, the control unit 25 notifies the numerical controller 10 whether a displacement occurrence log is stored in the storage device 26.The storage device 26 stores the threshold value for the determination of the displacement of the numerical controller 10, the threshold value is calculated in advance, and is stored in the storage device 26 by a manufacturer of the displacement detection device 20 or the like in consideration of a detection error of the sensor 23, an error of the A / D converter 24, a variation of the components used in the displacement detection device 20, a current measurement value at the time of the displacement of the numerical controller 10, and the like. In addition, a log indicating an operation state of the displacement detection device 20 is stored in the storage device 26. The log indicating the operation state includes the above-described displacement occurrence log which is a determination result obtained when the control unit 25 of the displacement detection device 20 determines that the numerical controller 10 has been displaced.The power supply control circuit 21 includes a secondary battery 211 as an emergency power supply. When the numerical controller 10 is in the on state, the power supply control circuit 21 is supplied with power from the power supply unit 12 of the numerical controller 10 via the external interface 15. When power is supplied from the power supply unit 12 to the numerical controller 10, the power supply control circuit 21 controls the electronic switch 22 with a power supply switching signal, and selects the power supply unit 12 of the numerical controller 10 as a power supply source for the sensor 23, the A / D converter 24, the control unit 25, and the storage device 26. Moreover, the power supply control circuit 21 charges the secondary battery 211 for emergency power supply using the power supplied from the power supply unit 12 of the numerical controller 10 when power is supplied from the power supply unit 12 of the numerical controller 10. It is assumed that the power supply control circuit 21 measures the voltage of the supply path for the power supplied from the power supply unit 12 to the numerical controller 10 via the external interface 15 when the numerical controller 10 is in a turned-on state.As described above, the numerical controller 10 interrupts the power supply to the displacement detection device 20 via the external interface 15 when the state of the numerical controller 10 changes from an on state to an off state. The power supply control circuit 21 detects that the state of the numerical controller 10 has changed from the on state to the off state, based on the decrease in the voltage of the power supply path. When the voltage of the power supply path becomes equal to or lower than the above-described threshold value obtained in consideration of a margin based on a lower limit voltage at which the control unit 25 can operate, the power supply control circuit 21 outputs a power supply switching signal to the electronic switch 22 to control the electronic switch 22, and switches the power supply source for the sensor 23, the A / D converter 24, the control unit 25, and the storage device 26. Specifically, the power supply control circuit 21 selects the secondary battery 211 of the power supply control circuit 21 as a power supply source for the sensor 23, the A / D converter 24, the control unit 25, and the storage device 26. Thus, the power supply control circuit 21 supplies power to the sensor 23, the A / D converter 24, the control unit 25, and the storage device 26 when the numerical controller 10 is in an off state. As a result, the displacement detection device 20 can continue its operation, i.e., can continue to monitor the numerical controller 10 and detect displacement of the numerical controller 10 even when the numerical controller 10 is in an off state. Note that the power supply control circuit 21 may include a capacitor (not illustrated) as an emergency power supply instead of the secondary battery 211.Next, the configuration of the display device 30 will be described. As illustrated in FIG. 1, the display device 30 includes a display unit 31. the display unit 31 displays, to an operator, states and the like of the numerical controller 10 and the machine tool 40 under the control of the control unit 11 of the numerical controller 10. For example, when the function of the numerical controller 10 is restricted due to a displacement of the numerical controller 10, the display unit 31 provides, under the control of the control unit 11, an alarm display or the like to the numerical controller 10 indicating that the function of the numerical controller 10 is restricted.The machine tool 40 is a five-axis or more-axis device capable of machining a workpiece with a plurality of tools. The machine tool 40 is, for example, a device that is machined, but is not limited thereto. The machine tool 40 may be a device that performs laser machining, a device that performs electric discharge machining, or the like. Note that the numerical controller 10 and the machine tool 40 may be configured such that the machine tool 40 is equipped with the numerical controller 10, i.e., the numerical controller 10 may be mounted in the machine tool 40. In this case, the displacement of the numerical controller 10 is equivalent to the displacement of the machine tool 40 equipped with the numerical controller 10.The operation of the numerical controller 10 will be described in detail below. When the power supply of the numerical controller 10 is turned on, the trajectory control unit 111 of the numerical controller 10 communicates with the control unit 25 of the displacement detection device 20. the trajectory control unit 111 determines whether the numerical controller 10 has been displaced while the numerical controller 10 has been in a turned-off state by checking, via the control unit 25, whether a displacement occurrence log is stored in the storage device 26 of the displacement detection device 20. Specifically, when no log on the occurrence of displacement is stored in the storage device 26 of the displacement detection device 20, the trajectory control unit 111 determines that the numerical controller 10 has not been displaced while the numerical controller 10 is in the turned-off state. When a log of the occurrence of displacement is stored in the storage device 26 of the displacement detection device 20, the trajectory control unit 111 determines that the numerical controller 10 has been displaced while the numerical controller 10 is in a turned-off state.The method by which the trajectory control unit 111 checks whether a displacement occurrence log is stored in the storage device 26 of the displacement detection device 20 is not particularly limited. For example, the trajectory control unit 111 requests the control unit 25 of the displacement detection device 20 to provide information on whether a log on the occurrence of displacement is stored in the storage device 26, and the control unit 25 of the displacement detection device 20 provides the information on whether a log on the occurrence of displacement is stored in the storage device 26 to the trajectory control unit 111. Note that the trajectory control unit 111 may request the control unit 25 of the displacement detection device 20 to read protocols stored in the storage device 26, acquire the protocols, and check whether a protocol about the occurrence of displacement is included in the acquired protocols.When it is determined that the numerical controller 10 has not been moved, the trajectory control unit 111 reads a program stored in the storage device 13 via the storage device interface 113 and a program stored in the storage device 14 via the storage device interface 114. The numerical controller 10 controls the machine tool 40 by executing a program stored in the storage device 13 and used when the control procedure based on the path control function is executed for five or more axes or a program stored in the storage device 14 and used when the control procedure based on the path control function is executed for four or less axes.When it is determined that the numerical controller 10 has been moved, the trajectory control unit 111 controls the storage device interface power supply circuit 112 so as to stop supply of control power from the storage device interface power supply circuit 112 to the storage device interface 113. The case where the trajectory control unit 111 reads a log of occurrence of displacement from the storage device 26 of the displacement detection device 20 is considered as an abnormal case. As a result, the trajectory control unit 111 cannot read a program stored in the storage device 13 via the storage device interface 113 and disables the trajectory control hardware 16 for five or more axes. In this case, the trajectory control unit 111 reads a program stored in the storage device 14 via the storage device interface 114 and activates the trajectory control hardware 17 for four or less axes. The numerical controller 10 thus controls the machine tool 40 by executing the program stored in the storage device 14 and used when the control procedure based on the trajectory control function is executed for four or less axes. As described above, the trajectory control unit 111 initiates a functional constraint when it determines that the numerical controller 10 has been moved to disable the trajectory control hardware 16 for five or more axes.When the numerical controller 10 has not been moved, the storage device interface power supply circuit 112 is powered by the power supply unit 12, the storage device interface power supply circuit 112 generates a control current for the storage device interface 113 to supply the generated control current to the storage device interface 113, and a control current for the storage device interface 114 to supply the generated control current to the storage device interface 114, under the control of the trajectory control unit 111. The storage device interface 113 may read a program stored in the storage device 13 when receiving the control current for the storage device interface 113 from the storage device interface power supply circuit 112. The storage device interface 114 may read a program stored in the storage device 14 when receiving the control current from the storage device interface power supply circuit 112 for the storage device interface 114.In contrast, under the control of the trajectory control unit 111, the storage device interface power supply circuit 112 does not generate a control current for the storage device interface 113 and does not supply a control current for the storage device interface 113 to the storage device interface 113 when the numerical controller 10 has been moved. Note that even if the numerical controller 10 has been moved, a control current for the storage device interface 114 is generated from the storage device interface power supply circuit 112 and the control current is supplied to the storage device interface 114. When the numerical controller 10 has been moved, the storage device interface power supply circuit 112 only stops generation of the control current for the storage device interface 113 and only interrupts supply of the control current to the storage device interface 113. As a result, the operation of the path control hardware 16 is stopped, i.e., disabled, for five or more axes.When the control unit 11 includes a single electrical component such as an LSI (Large-Scale Integration) system, the storage device interface power supply circuit 112 and the storage device interface 113 are included in the same LSI system. In this case, a supply line for the control current to be supplied from the memory device interface power supply circuit 112 to the memory device interface 113 constitutes a closed circuit in the LSI system. Therefore, a person who has moved the numerical controller 10 cannot turn on the storage device interface 113 by connecting a power source to the storage device interface 113 and supplying control power from the outside of the control unit 11, i.e., the LSI system.Further, when the control power supply from the storage device interface power supply circuit 112 to the storage device interface 113 is interrupted, the power supply line from the storage device interface power supply circuit 112 to the storage device interface 113 in the LSI system may be grounded at 0 V (GND). Therefore, it is not possible for a person who has moved the numerical controller 10 to remove the power supply line of the storage device interface 113 from the LSI system, connect an external power source, and turn on the storage device interface 113 by modification.In addition, the logic circuit of the LSI system has been fixed before mounting on a board and cannot be overwritten after mounting on the board. Therefore, a person who has moved the numerical controller 10 cannot turn on the storage device interface 113 by overwriting the logic circuit.Next, the treatment of a case where the displacement detection device 20 is not connected to the numerical controller 10 will be described. When the power supply of the numerical controller 10 is turned on, the trajectory control unit 111 of the numerical controller 10 determines whether the displacement detection device 20 is connected to the numerical controller 10. When the displacement detection device 20 is not connected to the numerical controller 10, the trajectory control unit 111 controls the storage device interface power supply circuit 112 such that supply of control power from the storage device interface power supply circuit 112 to the storage device interface 113 is interrupted, similarly to the case where displacement is detected. The case where the displacement detection device 20 is not connected to the numerical controller 10 is considered as an abnormal case. Thus, when a communication failure occurs, it is an abnormal case. As a result, the trajectory control unit 111 cannot read out a program stored in the storage device 13 via the storage device interface 113 and disables the trajectory control hardware 16 for five or more axes. In this case, the trajectory control unit 111 reads out a program stored in the storage device 14 via the storage device interface 114 and activates the trajectory control hardware 17 for four or less axes. As described above, the trajectory control unit 111 activates a function restriction for blocking the trajectory control hardware 16 for five or more axes even when it determines that the displacement detection device 20 is not connected to the numerical controller 10.Specifically, while the numerical controller 10 is in a turned-on state, the trajectory control unit 111 communicates with the control unit 25 of the displacement detection device 20. The trajectory control unit 111 may determine that the displacement detection device 20 has been removed from the external interface 15 of the numerical controller 10 based on a communication failure interruption occurring at the time of a communication failure.When it is determined that the displacement detection device 20 has been removed from the external interface 15 of the numerical controller 10 while the numerical controller 10 was in an on state, the trajectory control unit 111 controls the storage device interface power supply circuit 112 and interrupts the supply of control power from the storage device interface power supply circuit 112 to the storage device interface 113, similarly to the case where displacement of the numerical controller 10 is detected. As a result, the trajectory control unit 111 cannot read out a program stored in the storage device 13 via the storage device interface 113 and disables the trajectory control hardware 16 for five or more axes. In this case, the trajectory control unit 111 reads out a program stored in the storage device 14 via the storage device interface 114 and activates the trajectory control hardware 17 for four or less axes. As described above, when it is determined that the displacement detection device 20 has been removed from the external interface 15 of the numerical controller 10 while the numerical controller 10 was in an on state, the trajectory control unit 111 activates a function restriction to deactivate the trajectory control hardware 16 for five or more axes.In the displacement detection device 20, the sensor 23, the A / D converter 24, the control unit 25, the storage device 26, and the power supply control circuit 21 are supplied with power from the power supply unit 12 of the numerical controller 10 via the external interface 15.The power supply control circuit 21 of the displacement detection device 20 includes the secondary battery 211 as an emergency power supply, and is supplied with power from the power supply unit 12 of the numerical controller 10 via the external interface 15 while the numerical controller 10 is in a turned-on state. While the numerical controller 10 is in an on state, the secondary battery 211 is charged by the power supply control circuit 21. When the numerical controller 10 is in an off state, the power supply control circuit 21 detects a voltage drop in the supply path of the power supplied from the power supply unit 12 of the numerical controller 10. When the detected voltage reaches a threshold value determined in consideration of the margin on the basis of the lower limit voltage at which the control unit 25 can operate, the power supply control circuit 21 outputs a power supply switching signal to the electronic switch 22 of the displacement detection device 20. The power supply control circuit 21 switches the power supply path for the sensor 23, the A / D converter 24, the control unit 25, and the storage device 26 from the power supply unit 12 of the numerical controller 10 to the secondary battery 211, so that the displacement detection device 20 can continue operation even when the numerical controller 10 is in a turned-off state.When the numerical controller 10 has been displaced, the control unit 25 of the displacement detection device 20 compares a digital data acquisition value acquired from the A / D converter 24 with the threshold value stored in advance in the storage device 26, determines that the numerical controller 10 has been displaced, and stores a displacement occurrence log in the storage device 26, regardless of the on / off state of the numerical controller 10, and further, when the displacement detection device 20 has been removed from the numerical controller 10 while the numerical controller 10 has been in a turned-off state, and the displacement detection device 20 is connected to the original numerical controller 10 after the displacement of the numerical controller 10, the control unit 25 of the displacement detection device 20 may detect inertial changes that occur from the digital data acquisition value acquired from the A / D converter 24, when the displacement detection device 20 is removed from the numerical controller 10, such as a tilt, a movement, a vibration, and a shock. Also in this case, the control unit 25 of the displacement detection device 20 determines that the numerical controller 10 has been displaced, and stores a displacement occurrence log in the storage device 26.When the sensor 23 of the displacement detection device 20 fails due to disconnection, short circuit, or the like, a digital data acquisition value converted from an acquired analog data by the A / D converter 24 becomes a constant value exceeding the threshold value stored in advance in the storage device 26. When the sensor 23 of the displacement detection device 20 fails due to disconnection, short circuit, or the like, it is an abnormal case. In this case, the control unit 25 of the displacement detection device 20 determines that the state of the displacement detection device 20 is abnormal. When an abnormality is detected in the displacement detection device 20, the control unit 25 of the displacement detection device 20 stores, in the storage device 26, a log on the equipment abnormality indicating an abnormality of the displacement detection device 20. The control unit 25 of the displacement detection device 20 notifies the numerical controller 10 of the presence or absence of a log about an equipment abnormality in response to a request from the numerical controller 10.When there is a log about an equipment abnormality in the storage device 26 of the displacement detection device 20, the trajectory control unit 111 of the numerical controller 10 determines that the displacement detection device 20 is in a state in which the displacement detection device 20 cannot usually detect displacement, and performs control similar to the case in which the displacement detection device 20 has detected displacement of the numerical controller 10. The path control unit 111 thus controls the storage device interface power supply circuit 112 and interrupts the control power supply from the storage device interface power supply circuit 112 to the storage device interface 113. As a result, the trajectory control unit 111 cannot read out a program stored in the storage device 13 via the storage device interface 113 and disables the trajectory control hardware 16 for five or more axes. In this case, the trajectory control unit 111 reads a program stored in the storage device 14 via the storage device interface 114 and activates the trajectory control hardware 17 for four or less axes. As described above, when it is determined that the displacement detection device 20 is in a state where the displacement detection device 20 cannot usually detect displacement, the trajectory control unit 111 sets a function restriction to deactivate the trajectory control hardware 16 for five or more axes.When the voltage of the secondary battery 211 included in the power supply control circuit 21 of the displacement detection device 20 decreases while the numerical controller 10 is in an off state and reaches the lower limit voltage at which the control unit 25 can operate, the control unit 25 determines that the displacement detection device 20 is in an abnormal state, and stores a log on the equipment abnormality in the storage device 26.When the numerical controller 10 is in the state of the limitation function, the trajectory control unit 111 of the numerical controller 10 controls the display unit 31 of the display device 30 and causes an alarm display such as "five-axis control disabled" to be displayed on the display unit 31, so that an operator can visually confirm that the numerical controller 10 is in the state of the limitation function at the time of operation. As a result of checking the alarm display displayed on the display unit 31 of the display device 30, the operator can recognize that the path control hardware 16 for five or more axes in the numerical controller 10 has been deactivated and that the function is restricted.When the numerical controller 10 is in the state of the function restriction and an operator tries to perform trajectory control for five or more axes, the trajectory control hardware 16 for five or more axes is disabled and the program for the trajectory control for five or more axes cannot be read or written in the numerical controller 10, so that the program for the trajectory control for five or more axes does not run. Note that the four-axis or less-axis path control program may be run in the numerical controller 10 even when the numerical controller 10 is in the state of the function restriction. An operator can perform the path control for four or less axes by using the numerical controller 10.The operation of the numerical controller 10 will be described with reference to a flowchart. FIG. 2 is a flowchart illustrating the operation of the numerical controller 10 according to the present embodiment.The operator turns on the power supply to the numerical controller 10 and the display device 30 (step S 1) to activate both the numerical controller 10 and the display device 30. The power supply control circuit 21 of the displacement detection device 20 detects the voltage of the power supply unit 12 caused by the turning on of the numerical controller 10. When the voltage of the power supply unit 12 reaches the rated voltage, the power supply control circuit 21 outputs a power supply switching signal to the electronic switch 22 of the displacement detection device 20, and switches the power supply path for the sensor 23, the A / D converter 24, the control unit 25, and the storage device 26 from the secondary battery 211 to the power supply unit 12 of the numerical controller 10.The numerical controller 10 starts loop processing of steps S 3 and S 4 to be described below after the power supply to the numerical controller 10 and the display device 30 is turned on and the respective systems of the numerical controller 10 and the display device 30 are started (step S 2).The trajectory control unit 111 of the numerical controller 10 checks whether communication between the displacement detection device 20 and the numerical controller 10 is possible (step S 3). Specifically, the trajectory control unit 111 checks whether communication can be made between the control unit 25 of the displacement detection device 20 and the trajectory control unit 111 of the numerical controller 10. When the displacement detection device 20 is connected to the numerical controller 10 and communicable (step S 3: YES), the trajectory control unit 111 proceeds to step S 4. When communication is not possible due to the removal, the failure, or the like of the displacement detection device 20 (step S 3: NO), the trajectory control unit 111 determines that the displacement detection device 20 is in an abnormal state, and proceeds to step S 6.When the displacement detection device 20 is connected to the numerical controller 10 and communicable (step S 3: Yes), the trajectory control unit 111 monitors the protocols stored in the storage device 26 by communication with the control unit 25 of the displacement detection device 20. Specifically, the control unit 25 transmits, to the trajectory control unit 111, information on whether a displacement occurrence log is stored in the storage device 26. Based on the information obtained from the control unit 25, the trajectory control unit 111 checks whether a displacement occurrence log or an equipment abnormality log is present in the storage device 26 of the displacement detection device 20 (step S 4). When there is a log on the occurrence of displacement in the storage device 26 of the displacement detection device 20 (step S 4: YES), the trajectory control unit 111 determines that the numerical controller 10 has been displaced, and proceeds to step S 6. When an equipment abnormality is stored in the storage device 26 of the displacement detection device 20 (step S 4: YES), the trajectory control unit 111 determines that an abnormality exists in the displacement detection device 20, and proceeds to step S 6. Note that the trajectory control unit 111 proceeds to step S 6 when a displacement occurrence log is stored in the storage device 26 of the displacement detection device 20 (step S 4: YES). When neither a displacement occurrence log nor a device abnormality log is stored in the storage device 26 of the displacement detection device 20 (step S 4: NO), the trajectory control unit 111 returns to step S 3 by loop processing.After the start of the systems of the numerical controller 10 and the display device 30, when loop processing of steps S 3 and S 4 is completed, the numerical controller 10 returns to step S 3 and performs the next loop processing of steps S 3 and S 4 (step S 5).In the case of step S 3: No or step S 4: Yes, the trajectory control unit 111 sets a function restriction to deactivate the trajectory control hardware 16 for five or more axes and activate the trajectory control hardware 17 for four or less axes (step S 6). Specifically, by controlling the storage device interface power supply circuit 112, the trajectory control unit 111 interrupts the supply of control power from the storage device interface power supply circuit 112 to the storage device interface 113. The trajectory control unit 111 thus interrupts the power supply from the storage device interface power supply circuit 112 to the storage device interface 113 when a displacement occurrence log indicating that the numerical controller 10 has been displaced and / or an equipment abnormality log indicating an abnormality of the displacement detection device 20 is stored in the storage device 26 included in the displacement detection device 20. As a result, the trajectory control unit 111 cannot read a program stored in the storage device 13 via the storage device interface 113, thereby disabling the trajectory control hardware 16 for five or more axes. The trajectory control unit 111 further supplies power from the storage device interface power supply circuit 112 to the storage device interface 114 so that the trajectory control unit 111 can read a program stored in the storage device 14 via the storage device interface 114, thereby enabling the trajectory control hardware 17 for four or less axes. Consequently, the numerical controller 10 enables the trajectory control hardware 17 for four or less axes even if a function restriction is made due to wrong detection, so that the impact on a customer can be reduced.The trajectory control unit 111 controls the display unit 31 of the display device 30, and causes a warning display, i.e., an alarm display indicating that the numerical controller 10 is in the state of the function restriction, to be displayed on the display unit 31 (step S 7). The display unit 31 displays an alarm display such as "five-axis control disabled" under the control of the trajectory control unit 111, so that an operator can visually recognize that the numerical controller 10 is in the state of the function restriction at the time of operation. By checking details displayed on the display unit 31 of the display device 30, the operator can recognize the state of step S 6, i.e., recognize that the five-axis or more trajectory control hardware 16 in the numerical controller 10 has been deactivated and that the function is restricted.The displacement detection device 20 receives a restriction release input for releasing the function restriction set for the numerical controller 10 from a technician performing services such as repair and maintenance on devices such as the numerical controller 10 and the displacement detection device 20, respectively (step S 8). When the numerical controller 10 is in the state of the constraint, the technician may cancel the constraint set for the numerical controller 10 by deleting a displacement occurrence log stored in the storage device 26 of the displacement detection device 20 when the displacement detection device 20 is connected to the numerical controller 10. It should be noted that the method of deleting the log stored in the storage device 26 about the occurrence of relocations is not intended to be disclosed to a user. As a result, the user cannot freely delete the log on the occurrence of relocations stored in the storage device 26. Further, when a log about an equipment abnormality is stored in the storage device 26 of the displacement detection device 20, an abnormality exists in the displacement detection device 20. Therefore, the technician repairs or replaces the displacement detection device 20.After the restriction release performed by the technician, the trajectory control unit 111 of the numerical controller 10 starts communication between the displacement detection device 20 and the numerical controller 10 (step S 9). Here, it is assumed that communication between the displacement detection device 20 and the numerical controller 10 is performed as intended.The trajectory control unit 111 controls and causes the storage device interface power supply circuit 112 to supply control power to the storage device interface 113, and restore the storage device interface 113 to a state in which the storage device interface 113 can read a program stored in the storage device 13. As a result, the trajectory control unit 111 enables the trajectory control hardware 16 for five or more axes to cancel the function restriction imposed on the numerical controller 10 (step S 10).The trajectory control unit 111 controls and causes the display unit 31 of the display device 30 to cancel the alarm display on the display unit 31 indicating that the numerical controller 10 is in the state of the function limitation (step S 11).The operator turns off the power supply of the numerical controller 10 and the display device 30 (step S 12). The power supply control circuit 21 of the displacement detection device 20 detects a voltage drop of the power supply unit 12 of the numerical controller 10 and outputs a power supply switching signal to the electronic switch 22 of the displacement detection device 20 when the detected voltage drops and reaches the threshold value obtained in consideration of the margin based on the lower limit voltage at which the control unit 25 can operate. The displacement detection device 20 switches the power supply path for the sensor 23, the A / D converter 24, the control unit 25, and the storage device 26 from the power supply unit 12 of the numerical controller 10 to the secondary battery 211, so that the displacement detection device 20 can continue the operation, i.e., monitoring the displacement of the numerical controller 10 even when the power supply of the numerical controller 10 and the display device 30 has been turned off. Note that the displacement detection device 20 may switch the power supply path for the sensor 23, the A / D converter 24, the control unit 25, and the storage device 26 from the power supply unit 12 of the numerical controller 10 to the secondary battery 211 in a similar manner, and continue monitoring the displacement of the numerical controller 10 when the power supply of the numerical controller 10 is turned off while the loop processing of steps S 3 and S 4 is executed.Next, the hardware configuration of a numerical controller 10 will be described. FIG. 3 is a diagram illustrating an example of the hardware configuration of a numerical controller 10 according to the present embodiment. As illustrated in FIG. 3, the numerical controller 10 includes a computer having a processor 91, a memory 92, and an interface circuit 93.The processor 91, the memory 92 and the interface circuit 93 can transmit and receive information to and from each other via a bus 94, for example. The storage devices 13 and 14 are implemented by the memory 92. The external interface 15 is implemented by the interface circuit 93. The processor 91 performs the functions of the control unit 11, the power supply unit 12, and the like by reading and executing programs stored in the memory 92. The power supply unit 12 may be realized by a converter circuit or the like that can generate the desired current. The processor 91 is an example of a processing circuit, and includes, for example, a central processing unit (CPU) and / or a digital signal processor (DSP) and / or an LSI system.The memory 92 includes random access memory (RAM) and / or read only memory (ROM) and / or flash memory and / or erasable programmable read only memory (EPROM) and / or electrically erasable programmable read only memory (EEPROM) (registered trademark) and / or hard disk drive (HDD) and / or solid state drive (SSD). In addition, the memory 92 includes a recording medium on which a computer readable program is stored. Such a recording medium includes a nonvolatile or volatile semiconductor memory and / or a magnetic disk and / or a flexible memory and / or an optical disk and / or a compact disk and / or a digital versatile disk (DVD). Note that the numerical controller 10 may include integrated circuits such as application specific integrated circuits (ASIC) and field programmable gate arrays (FPGA).The hardware configuration of the numerical controller 10 has been described. As with the numerical controller 10, the displacement detection device 20 is also implemented by the hardware configuration illustrated in FIG. 3.As described above, according to the present embodiment, when a displacement of the numerical controller 10 is detected in the displacement detection device 20, the numerical controller 10 stops generation and supply of control current from the storage device interface power supply circuit 112 to the storage device interface 113, electrically interrupts reading and writing of a program of the storage device 13 storing the program to be used when the control procedure based on the trajectory control function is executed for five or more axes, and disables the trajectory control hardware 16 for five or more axes. As a result, in the numerical controller 10, deactivation of a location change prevention function due to hardware modification can be prevented.Moreover, the numerical controller 10 stores the program to be used when the control procedure based on the four-axis or less-axis trajectory control function is executed in the storage device 14 provided separately from the storage device 13 storing the program to be used when the control procedure based on the five-axis or more-axis trajectory control function is executed. Therefore, the numerical controller 10 can activate the four-axis or less trajectory control hardware 17 including the storage device 14 while deactivating the five-axis or more trajectory control hardware 16 including the storage device 13, and thus it is possible to reduce the customer's impairment in misacquiring as much as possible. Note that, in the present embodiment, the numerical controller 10 is configured such that the storage device 13 storing the first program is provided separately from the storage device 14 storing the second program; however, both programs may be stored in the same storage device, and switching between enabling and disabling reading of each program may be performed by software. In this case, the control unit 11 of the numerical controller 10 communicates with the displacement detection device 20. In this case as well, the same effect as in the present embodiment can be obtained. Further, since displacement of the numerical controller 10 is detected by the displacement detection device 20 which is a unit provided separately from the numerical controller 10, it is possible to more inexpensively manufacture the numerical controller 10 having a configuration similar to the conventional configuration and standardize the model of the numerical controller 10. The function of the displacement detection device 20 can be easily added to the numerical controller 10 by connecting the numerical controller 10 to the displacement detection device 20 which is a unit separately provided therefrom.The configurations illustrated in the above embodiment are examples, and it is possible to combine the configurations with another known technique or combine the embodiments with each other, and it is also possible to partially omit or change the configurations without departing from the scope.List of reference characters10 NUMERICAL CONTROLLER; 11, 25 CONTROLLER; 12 POWER SUPPLY UNIT; 13, 14, 26 STORAGE DEVICE; 15 EXTERNAL INTERFACE; 16 TRAJECTORY CONTROL HARDWARE FOR FIVE OR MORE AXES; 17 TRAJECTORY CONTROL HARDWARE FOR FOUR OR LESS AXES; 20 DISPLACEMENT DETECTOR; 21 POWER SUPPLY CONTROL CIRCUIT; 22 ELECTRONIC SWITCH; 23 SENSOR; 24 A / D converter; 30 display device; 31 display unit; 40 machine tool; 111 TRAJECTORY CONTROL UNIT; 112 STORAGE DEVICE INTERFACE POWER SUPPLY CIRCUIT; 113, 114 STORAGE DEVICE INTERFACE; 211 SECONDARY BATTERY.

Claims

A numerical controller (10) for use with a machine tool (40) having five or more axes, the numerical controller (10) comprising: first path control hardware (16) capable of performing path control for five or more axes on the machine tool (40); second path control hardware (17) capable of performing path control for four or less axes on the machine tool (40); and a path control unit (111) for performing the control such that the first path control hardware (16) fails to function when a displacement of the numerical controller (10) is detected in a displacement detection device (20) capable of detecting a displacement of the numerical controller (10).The numerical controller (10) according to claim 1, wherein the first trajectory control hardware (16) comprises a first storage device (13) to store a program to be used when the numerical controller (10) performs a control procedure based on a trajectory control function for five or more axes, and the trajectory control unit (111) electrically interrupts reading from and writing to the first storage device (13) when a displacement of the numerical controller (10) is detected in the displacement detection device (20).The numerical controller (10) according to claim 1 or 2, wherein the first trajectory control hardware (16) comprises a first storage device interface (113) capable of reading and writing a program to be used when the numerical controller (10) performs a control procedure based on a trajectory control function for five or more axes, the trajectory control unit (111) interrupts the power supply from a storage device interface power supply circuit (112) to the first storage device interface (113) when a displacement of the numerical controller (10) is detected in the displacement detection device (20), wherein the storage device interface power supply circuit (112) supplies power to the first storage device interface (113) when no displacement of the numerical controller (10) is detected, and the first storage device interface (113) and the storage device interface power supply circuit (112) are included in a single electrical component.The numerical controller (10) according to claim 3, wherein the trajectory control unit (111) controls the power supply from the storage device interface power supply circuit (112) to the first storage device interface (113) on the basis of a log stored in a storage device (26) included in the displacement detection device (20).The numerical controller (10) according to claim 4, wherein the trajectory control unit (111) interrupts the power supply from the storage device interface power supply circuit (112) to the first storage device interface (113) when a displacement occurrence log and / or an equipment abnormality occurrence log is stored in the storage device (26) included in the displacement detection device (20), the displacement occurrence log indicates that the numerical controller (10) has been displaced, and the equipment abnormality occurrence log indicates an abnormality in the displacement detection device (20).

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