Numerical control for a machine tool with an efficient regular inspection function for components

Abstract

Numerical control device (10) configured to drive and control a machine tool, wherein the numerical control device has a function for communicating the time to carry out an inspection of forming components of a machine, comprising: a first recording unit (101) configured to record an inspection reference condition size (Lim) for each of the components x0 ) to set and maintain, which serves as a criterion for determining whether the time for carrying out the inspection of the component has been reached or not; an environment information acquisition unit configured to obtain information regarding an environment in which the machine or component is located; a cumulative value counter (102) configured to: - to measure and accumulate a state variable for each of the components to estimate the service life of the component and to calculate a resulting cumulative value (Cnt) x to maintain, and - to multiply the state variable to be accumulated by a coefficient in order to find the cumulative value in a case where a decision is made that the information obtained by the environmental information acquisition unit affects the lifetime of the component, where, for a component whose lifetime is likely to be affected depending on whether or not a coolant is used, reference is made to code in a program instructing the discharge of coolant or a signal to control the coolant pump in the numerical control device, and when it is decided that the coolant has been discharged, the cumulative value is multiplied by the coefficient so that a value greater than that accumulated when the coolant is absent; a notification unit (103) configured to send a notification reminding the component of the inspection time when the state variable accumulated in the cumulative value counter reaches the inspection reference state variable; an input unit (104) configured to input a result of the inspection of the component after the output of the message that recalls the inspection time of the component from the message unit; a change unit (105) configured to change the inspection reference condition variable to determine the time to perform the next inspection based on the inspection result entered by the input unit; and a second recording unit (101) configured to receive at least one extension state variable (Exp1, Exp2, Exp) from a component n) to extend the inspection reference condition size, which is maintained in the recording unit, if, as a result of the inspection of the component, a decision is made that the component can continue to be used, wherein the input unit includes: a first operating unit (71) that is configured to be operated when an operator decides that the component is continuously usable; and a second operating unit (71) which is configured to be operated when the operator decides that the component's service life has reached its end and replaces the component, and The unit of change comprises: a first computing unit configured to add, when the first operating unit is operated, the extension state size recorded in the second recording unit to the inspection reference state size recorded in the first recording unit, in order to create an inspection reference state size (Lim x1 , Lim xn ) to locate for the next inspection; and a second computing unit configured to clear the state variable accumulated by the cumulative value counter when the second operating unit is operated, in order to find an inspection reference state variable for the next inspection.

Description

Background of the invention

[0001] The present invention relates to a numerical control device for a machine tool for a function of periodically inspecting components.

[0002] A number of components are used in machine tools, and the components are inspected regularly whenever possible and replaced immediately when it is determined that they have reached the end of their service life. However, it is not always easy to manage the inspection timing for each component. Therefore, as described in JP H02-173803 A, JP H10-320031 A, JP 2004-334507 A, and JP H07-225777 A, a technology is used that accumulates the operating time of a machine or the number of times components are used to send out a notification to prompt an operator to inspect the components when the accumulated value exceeds a reference value for performing an inspection.

[0003] When a notification indicating a component inspection is received from a machine tool control device, the operator inspects the component. If the operator determines, as a result of the inspection, that the component's service life has reached its end, they will replace the component and reset the numerical value accumulated up to that point. Some components requiring regular inspection and replacement have service lives that tend to vary significantly depending on the environment and usage condition of the machine tool.

[0004] Thus, according to the above-described method described in JP H02-173803 A, JP H10-320031 A, and JP 2004-334507 A, the inspection cycle is set without considering the usage environment, which increases wasteful operation in the usage environment where the service life of the component can be extended by setting a smaller reference value. Conversely, in the usage environment where the service life could be shortened by setting a larger reference value for the inspection cycle, the service life of the component may reach its end before the inspection is performed.

[0005] According to the above-described technology described in JP H07-225777 A, a reference value for performing inspection is changed based on data from the usage environment. However, this requires presetting a plurality of reference values ​​based on differences in the usage environment. Furthermore, there is a case where an element for which data is difficult to obtain, such as the influence of a coolant, affects the service life; this situation becomes more complicated to manage.

[0006] DE 198 00 714 A1 discloses a method for maintaining an elevator installation and an elevator installation. In the installation or method, predetermined maintenance intervals are not rigid, but can be varied by sensors that monitor the condition or settings of various hardware components. For example, several hardware components of the elevator can be equipped with sensors that provide information about the settings and / or wear of the hardware components to the control system and / or the maintenance system. These signals can be used to advance or delay a maintenance interval for a group, depending on the individual condition of the time-determining hardware component in the group or module. The date for performing a maintenance module can also be postponed by manual entry, for example if unscheduled maintenance has been performed on certain hardware components. Summary of the invention

[0007] Therefore, in view of the above-described circumstances, an object of the invention is to provide a numerical control device for a machine tool having a function for efficiently performing a periodic inspection of components adjusted to the environment and the usage state of the machine tool.

[0008] According to the invention, a device is provided according to the independent claim. Developments are set out in the dependent claims.

[0009] Embodiments of the present invention provide a numerical control apparatus for a machine tool having an efficient periodic inspection function for components adapted to the environment and usage conditions of the machine tool. Short description of the drawings

[0010] The above-described and other features of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings. Fig. 1 shows a process for notifying the timing of an inspection of a component to be performed by a numerical control device according to the invention; Fig. Fig. 2 is a descriptive view of a function provided for a numerical control device according to the invention; Fig. 3 is a block diagram of essential portions of a numerical control device according to an embodiment of the invention; and Fig. 4 is a flowchart showing a process for notifying the timing for inspection of a component to be performed by a numerical control device according to the invention. Detailed description of the preferred embodiments

[0011] Fig. 1 shows a process for notifying the timing for an inspection of a component to be performed by a numerical control device according to the invention.

[0012] In Fig. 1 shows (1) a state immediately after a start of a regular inspection, (2) shows a state in which a cumulative value Cnt x of inspection state variables including the operating time and the number of uses an initial value Lim x0 an inspection reference state variable, (3) shows a state in which a first operation unit (operated when an operator decides that the component is continuously usable) is operated for the first time, with an inspection reference state variable being increased by Exp1 to Lim x1is extended, (4) shows a state in which the first operating unit is operated n times, with the inspection reference state variable being increased by Exp n on Lim xn is extended, and (5) shows a state in which a second operation unit (which is operated when an operator decides that the service life of the component has reached its end and replaces the component) is operated, with a cumulative value Cnt x deleted and Lim x0 ' for an inspection reference state variable Lim x0 for the next inspection.

[0013] The numerical control device defines, with respect to a component with a component number x that involves inspection and replacement, an inspection state quantity including an operation time and the number of uses for estimating the service life of the component as a cumulative value Cnt xand accumulates the value for recording in a memory. Furthermore, the inspection reference state variable Lim x0 , which serves as a criterion for performing the inspection, is set for each component and recorded in the memory. Furthermore, the numerical control device includes the above-described first and second operation units. The first operation unit is operated in a case where the component is used continuously without replacement after the inspection, whereas the second operation unit is operated in a case where the component is replaced. The first operation unit and the second operation unit can be configured, for example, by a manual data input (MDI) 70 with a display of a numerical control device 10.

[0014] For each component requiring inspection and replacement, the cumulative value Cnt xThe inspection state quantities are updated by accumulation. It can be configured such that a state in which a machine or a component is placed is obtained, for example, from a control signal from the numerical controller, and the cumulative value is multiplied by a component in a case where the detected state is considered to affect the service life of the component. For example, in a case of a component whose service life is likely to be affected depending on whether or not a coolant is used, reference is made to a code in a program for instructing the discharge of coolant or a signal for controlling the coolant pump in the numerical controller, and in a case where it is judged that the coolant has been discharged, the cumulative value is multiplied by the coefficient so that a value larger than that in the absence of coolant is accumulated.In a process shown in the flowchart according to . Fig. 4 (which is described below), the cumulative value Cnt x possibly multiplied by the coefficient in step sa03.

[0015] If the cumulative value Cnt x the inspection reference state variable Lim x0, then a notification is sent to the operator regarding that the relevant component can be inspected by a method, such as a message displayed on a screen (e.g., a display of the MDI unit 70 of the numerical control device 10). Upon receiving the notification, the operator performs an inspection of the relevant component, and in a case where the component does not need to be replaced and use is continued as a result, the first operation unit is operated, while in a case where the component is replaced because the service life of the component has reached its end, the second operation unit is operated.This can be done by providing a "Continue" button and a "Replace" button on an operation panel 71 to be pressed at the time of inspection, or by displaying menu items such as "Continue" and "Replace" for selection on a screen of the numerical controller.

[0016] In a case where the first operating unit is operated, the cumulative value Cnt x not changed and becomes the inspection reference state variable of Lim x0 , changed to Limx1, where Limx1=Limx0+Exp1. Exp nRepresents a quantity (an extension state quantity) by which the inspection reference state quantity is extended in a case where the component is continued to be used without replacement as a result of the inspection. In addition, a formula is recorded in advance in the memory, and the formula for calculating the value is calculated based on a constant value or data obtained at the time of inspection.

[0017] The cumulative value Cnt x is updated again by accumulation, and a message is sent again when the inspection reference state variable Lim x1 is reached. The operator performs another inspection of the relevant component in response to the notification, and the first operating unit continues to be operated as long as the component continues to be used. The inspection reference state variable Lim xn is represented by Limxn=Limx0+Exp1+Exp2+…+Expn, when the first control unit is operated n times.

[0018] It should be noted that the extension state variable Exp n becomes smaller as the number of operations of the first control unit increases. This applies in particular Exp1>Exp2>…>Expn.

[0019] Fixed values ​​that satisfy the equation described above can be used for Exp1 to Exp n Alternatively, a formula can be developed, and the extension state variable can be reduced according to the formula.

[0020] Furthermore, in a case where the extension state variable Exp n used for the extension during operation of the first control unit, takes a minimum value recorded in the memory, prohibiting the operation of the first control unit from that moment on.

[0021] In a case where the service life of the component reaches its end and the component is therefore replaced as a result of the inspection, the second operating unit is operated. When the second operating unit is operated, the cumulative value Cnt is first x deleted. At the same time, the inspection reference state variable Lim x0 ' to serve as a criterion for the design of the next inspection. It should be noted that Lim x0 ' = A x Lim xn where A is a coefficient in setting the inspection reference state variable Lim x0 ' and furthermore A ≤ 1.

[0022] By the procedure described above, the inspection reference state variable Lim x0 ' a value that is set to the machine usage environment, and then messages are sent at appropriate intervals. Furthermore, the extension state variable Expn is reduced as the number of operations of the first operation unit increases, thus avoiding a situation in which the component reaches the end of its service life before the next inspection. In addition, the inspection reference value is set to a more appropriate value after the operation of the second operation unit. It should be noted that the identification of a minimum value among extension state variables is facilitated by each processing state variable Exp n with the number n of component continuation usage operations accumulated in descending order.

[0023] The numerical control device 10 for a machine tool includes a recording unit 101, a cumulative value counter 102, a notification unit 103, an input unit 104, and a change unit 105. The recording unit 101 sets and maintains, for each component, an inspection reference state quantity, which serves as a criterion for determining whether the timing for inspection of the component has been reached. The cumulative value counter 102 measures and accumulates a state quantity for estimating the service life of each component for each component and stores the accumulated state quantities in a memory. The notification unit 103 sends a notification indicating inspection of the component when the state quantity accumulated in the cumulative value counter 102 reaches the inspection reference state quantity. The input unit 104 inputs the result of the inspection of the component.The changing unit 105 changes the inspection reference state quantity to determine the timing of the next inspection based on the result of the inspection input by the input unit 104.

[0024] Fig. 3 is a block diagram showing essential portions of the numerical control apparatus according to an embodiment of the present invention.

[0025] A central processing unit (CPU) 11 reads a system program stored in a read-only memory (ROM) 12 through a bus 20 and controls the entire numerical control device 10 according to the system program. A random access memory (RAM) 13 temporarily stores calculation data and display data, as well as various data input by an operator via the display / MDI unit 70.

[0026] A static RAM (SRAM) 14 is configured as a non-volatile memory that maintains the memory state even when the numerical control device 10 is de-energized. A machining program read through an interface 15 and a machining program input via the display / MDI unit 70 are retained in the SRAM 14.

[0027] Furthermore, various system programs are prewritten in ROM 12 to enable execution of processing in an editing mode for creating and editing machine programs or for processing for automatic operation. Furthermore, a program for performing efficient periodic inspection of components according to the invention is stored in ROM 12.

[0028] Axis control circuits 30 to 32 for respective axes output instructions directed to each axis to servo amplifiers 40 to 42 in response to movement instructions for each axis from the CPU 11. In response to these instructions, the servo amplifiers 40 to 42 drive the servo motors 50 to 52 associated with the axes, respectively. The servo motors 50 to 52 associated with the axes, respectively, include position / speed sensors. Position / speed feedback signals from the position / speed sensors are fed back to the axis control circuits 30 to 32 to perform closed-loop control regarding position and speed. It should be noted that in Fig. 3 the feedback regarding position and speed is not shown.

[0029] The servo motors 50 to 52 drive the X, Y, and Z axes of the machine tool. A spindle control circuit 60 outputs a spindle speed signal to a spindle amplifier 61 in response to a spindle rotation command. The spindle amplifier 61 drives a spindle motor (SM) 62 at the commanded rotation speed in response to the spindle speed signal. The spindle motor (SM) 62 includes a speed sensor 63 and is configured to detect the rotation speed of the spindle motor (SM) 62 for feedback to the spindle control circuit 60.

[0030] The configuration of the numerical control device 10 described above is the same as that of existing numerical control devices. A three-axis machining center is driven and controlled by the numerical control device 10. The processor (CPU 11) of the numerical control device 10 then executes algorithms containing software to perform periodic component inspection.

[0031] Fig. 4 is a flowchart showing a process for notifying a component inspection timing to be performed by the numerical control device according to the invention. A description will be given below in accordance with the steps of the flowchart.

[0032] [Step sa01] The number n of component continuation use operations is initialized (n=0).

[0033] [Step sa02] The initial value Lim x0 the inspection reference state variable is read. The initial value Lim x0 the inspection reference state quantity is retained in advance in the memory of the numerical control device.

[0034] [Step sa03] State variables are calculated as cumulative value Cnt x accumulated.

[0035] [Step sa04] A decision is made whether the cumulative value Cnt x , which is accumulated in step sa03, is greater than the inspection reference state quantity Lim xn is or not. In the case where the cumulative value Cnt x , is greater (YES), the process proceeds to step sa05, and in the case where the cumulative value Cnt x , is not greater than (NO), the process returns to step sa03. Since initially n=0, the inspection reference state variable Lim xn the initial value Lim x0the inspection reference state quantity read in step sa02.

[0036] [Step sa05] A signal is sent indicating the inspection. To send such a signal, a buzzer, a red light, or a message on a screen is used, for example.

[0037] [Step sa06] A decision is made as to whether the component is to be used continuously or not. If continued use is determined (YES), the process proceeds to step sa07, and if continued use of the component is not determined, that is, replacement of the component is determined (NO), the process proceeds to step sa09. Specifically, an operator presses a "continue" button or a "replace" button provided on the numerical control device 10 at the time of inspection of the component, so that information regarding the decision as to whether the component is to be used continuously or replaced is output to the numerical control device 10.

[0038] [Step sa07] By adding to the inspection reference state variable for extension Exp n to the inspection reference state variable Lim xnthe inspection reference state variable Lim xn renewed.

[0039] [Step sa08] By adding 1 to the number n of component continuation use operations, the number n of component continuation use operations is renewed, and the process returns to step sa03.

[0040] [Step sa09] The cumulative value Cnt x , will be deleted.

[0041] [Step sa10] A value obtained by multiplying the inspection reference state quantity Lim xn with the coefficient A is freshly used as inspection reference state variable Lim x0 This process allows a decision as to whether the service life of the replaced component has reached its end, based on the inspection reference state variable Lim xn In other words, an inspection is carried out that correlates with the usage environment of a machine (component).

[0042] [Step sa11] The number n of component continuation use operations is initialized (n=0), and the process returns to step sa03.

Claims

[1] A numerical control device (10) adapted to drive and control a machine tool, the numerical control device having a function for notifying the timing for performing an inspection of constituent components of a machine, comprising: a first recording unit (101) configured to record an inspection reference state variable (Lim x0 ) which serves as a criterion for determining whether the time for carrying out the inspection of the component has been reached or not; an environment information acquiring unit configured to acquire information regarding an environment in which the machine or the component is placed; a cumulative value counter (102) configured to: - to measure and accumulate a state variable for each of the components to estimate a service life of the component and to calculate a resulting cumulative value (Cnt x ) and - to multiply the state quantity to be accumulated by a coefficient to find the cumulative value in a case where a decision is made that the information acquired by the environmental information acquiring unit affects the service life of the component, wherein, for a component whose service life is likely to be affected depending on whether or not a coolant is used, reference is made to a code in a program for instructing the discharge of coolant or a signal for controlling the coolant pump in the numerical control device, and when it is decided that the coolant has been discharged, the cumulative value is multiplied by the coefficient so that a value larger than that in the absence of the coolant is accumulated; a notification unit (103) configured to send a notification reminding the inspection timing of the component when the state quantity accumulated in the cumulative value counter reaches the inspection reference state quantity; an input unit (104) configured to input a result of the inspection of the component after the output of the notification reminding the inspection time of the component from the notification unit; a changing unit (105) configured to change the inspection reference state quantity for determining the timing for performing the next inspection based on the result of the inspection input by the input unit; and a second recording unit (101) configured to record at least one extension state variable (Exp1, Exp2, Exp n) to set and record the inspection reference state quantity maintained in the recording unit when, as a result of the inspection of the component, a decision is made that the component is still usable, where the input unit includes: a first operating unit (71) configured to be operated when an operator decides that the component is continuously usable; and a second operating unit (71) configured to be operated when the operator decides that the service life of the component has reached its end and replaces the component, and the change unit includes: a first calculation unit configured to add, upon operation of the first operation unit, the extension state quantity recorded in the second recording unit to the inspection reference state quantity recorded in the first recording unit to obtain an inspection reference state quantity (Lim x1 , Lim xn ) for the next inspection; and a second calculation unit configured to, upon operation of the second operation unit, clear the state quantity accumulated by the cumulative value counter to find an inspection reference state quantity for the next inspection. [2] The numerical control device according to claim 1, wherein the second recording unit is configured to record the inspection reference state quantity to be lengthened so as to be decreased according to an increase in the number of operations of the first operation unit. [3] A numerical control device according to claim 1, wherein the second calculation unit is configured to calculate a value (Lim x0 '), which is obtained by multiplying the inspection reference state quantity found by the first calculation unit by a coefficient not greater than 1, as the inspection reference state quantity for the next inspection. [4] The numerical control device according to claim 3, wherein the first operation unit is configured to prohibit its operation in a case where the extension state quantity used for the extension by the first calculation unit takes a minimum value among the extension state quantities recorded in the second recording unit.

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