Numerical control device and computer-readable storage medium

Abstract

The numerical control device includes: a spindle load detection section that detects time-series data of a load applied to a spindle when machining of a workpiece is performed; a target load setting section that sets a target load applied to the spindle; a machining time prediction section that predicts a machining time when a feed rate of the spindle is controlled such that the load applied to the spindle becomes the target load based on the time-series data; and a machining time output section that outputs data of the predicted machining time.

Description

Technical Field

[0001] This disclosure relates to numerical control devices for controlling machine tools and computer-readable storage media. Background Technology

[0002] In machine tools, a technique is known for controlling the spindle feed rate to keep the load applied to the spindle constant (e.g., Patent Document 1). This control can extend the tool life.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-117458 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, when the spindle feed rate is controlled in a way that the load applied to the spindle is constant, the feed rate changes accordingly with the load, making it difficult to predict the machining time in advance.

[0008] The purpose of this disclosure is to provide a numerical control device and a computer-readable storage medium that can predict machining time in advance while controlling the feed rate of the spindle to keep the load applied to the spindle constant.

[0009] Methods for solving problems

[0010] The numerical control device includes: a spindle load detection unit that detects timing data of the load applied to the spindle during workpiece machining; a target load setting unit that sets the target load applied to the spindle; a machining time prediction unit that predicts the machining time based on the timing data when the spindle feed speed is controlled in such a way that the load applied to the spindle becomes the target load; and a machining time output unit that outputs the predicted machining time data.

[0011] The computer-readable storage medium stores commands that enable the computer to perform the following processes: detect timing data of the load applied to the spindle during workpiece machining; set a target load applied to the spindle; predict the machining time based on the timing data when the spindle feed rate is controlled in such a way that the load applied to the spindle becomes the target load; and output the predicted machining time data.

[0012] Invention Effects

[0013] According to this disclosure, when the spindle feed rate is controlled in a manner that keeps the load applied to the spindle constant, the machining time can be predicted in advance. Attached Figure Description

[0014] Figure 1 This is a diagram illustrating an example of the hardware structure of a machine tool.

[0015] Figure 2 This is a block diagram illustrating an example of the function of a numerical control device.

[0016] Figure 3 This is a diagram illustrating an example of timing data stored in the spindle load storage section.

[0017] Figure 4A This is a diagram illustrating the method by which the processing time prediction department predicts processing time.

[0018] Figure 4B This is a diagram illustrating the method by which the processing time prediction department predicts processing time.

[0019] Figure 4C This is a diagram illustrating the method by which the processing time prediction department predicts processing time.

[0020] Figure 4D This is a diagram illustrating the method by which the processing time prediction department predicts processing time.

[0021] Figure 5 This is a diagram illustrating the method by which the processing time prediction department predicts processing time.

[0022] Figure 6 This is a flowchart illustrating an example of the processing flow performed by a numerical control device.

[0023] Figure 7 This is a diagram illustrating an example of a processing time prediction unit with a learning department.

[0024] Figure 8 This is a diagram showing an example of a display of processing time shown on an input / output device.

[0025] Figure 9 This is a block diagram illustrating an example of the function of a numerical control device.

[0026] Figure 10 This is a diagram showing an example of timing data for the load applied to the spindle.

[0027] Figure 11 This is a graph representing an example of frequency distribution. Detailed Implementation

[0028] Hereinafter, one embodiment of the present disclosure will be described using the accompanying drawings. Furthermore, not all combinations of the features described in the following embodiment are necessary to solve the problem. Also, sometimes unnecessary detailed descriptions are omitted. Additionally, the following description of the embodiment and the accompanying drawings are provided to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the scope of the claimed patent protection.

[0029] Figure 1 This is a diagram illustrating an example of the hardware structure of a machine tool. Machine tool 1 is, for example, a lathe, machining center, or multi-function machining center.

[0030] Machine tool 1, for example, includes numerical control device 2, input / output device 3, servo amplifier 4, servo motor 5, spindle amplifier 6, spindle motor 7, and auxiliary equipment 8.

[0031] The numerical control device 2 is a device that controls the entire machine tool 1. The numerical control device 2 includes a CPU (Central Processing Unit) 201, a bus 202, a ROM (Read Only Memory) 203, a RAM (Random Access Memory) 204, and a non-volatile memory 205.

[0032] CPU 201 is a processor that controls the entire numerical control device 2 according to the system program. CPU 201 reads the system program and other data stored in ROM 203 via bus 202. In addition, CPU 201 controls servo motor 5 and spindle motor 7 according to the machining program.

[0033] CPU201 performs tasks such as parsing the machining program and outputting control commands for the servo motor 5 in each control cycle.

[0034] Bus 202 is a communication path that connects the various hardware components within the numerical control device 2. The various hardware components within the numerical control device 2 exchange data via bus 202.

[0035] ROM 203 is a storage device that stores system programs and other data used to control the overall numerical control device 2. ROM 203 functions as a computer-readable storage medium.

[0036] RAM204 is a storage device for temporary storage of various data. RAM204 functions as the working area for CPU201 to process various data.

[0037] The non-volatile memory 205 is a storage device that retains data even when the power supply to the machine tool 1 is cut off and no power is supplied to the numerical control device 2. The non-volatile memory 205 stores, for example, machining programs and various parameters input from the input / output device 3. The non-volatile memory 205 functions as a computer-readable storage medium. The non-volatile memory 205 is, for example, constructed from an SSD (Solid State Drive).

[0038] The numerical control device 2 also includes an interface 206, an axis control circuit 207, a spindle control circuit 208, a PLC (Programmable Logic Controller) 209, and an I / O unit 210.

[0039] Interface 206 connects bus 202 and input / output device 3. Interface 206, for example, sends various data processed by CPU 201 to input / output device 3.

[0040] Input / output device 3 is a device that receives and displays various data via interface 206. Additionally, input / output device 3 accepts various data inputs and sends various data to CPU 201 via interface 206. Input / output device 3 includes a display such as an LCD (Liquid Crystal Display), a keyboard, and a mouse. Alternatively, input / output device 3 can also be a touch panel.

[0041] The axis control circuit 207 is a circuit that controls the servo motor 5. The axis control circuit 207 receives control commands from the CPU 201 and outputs commands to the servo amplifier 4 for driving the servo motor 5. For example, the axis control circuit 207 sends torque commands to the servo amplifier 4 to control the torque of the servo motor 5.

[0042] Servo amplifier 4 receives instructions from axis control circuit 207 and supplies current to servo motor 5.

[0043] The servo motor 5 is driven by receiving current from the servo amplifier 4. The servo motor 5 is connected, for example, to the tool post, spindle head, and ball screw driving the worktable. Driven by the servo motor 5, the machine tool 1's components, such as the tool post, spindle head, and worktable, move, for example, in the X-axis, Y-axis, or Z-axis directions. Additionally, the servo motor 5 may also have a built-in speed detector (not shown) for detecting the feed rate of each axis.

[0044] The spindle control circuit 208 is a circuit used to control the spindle motor 7. The spindle control circuit 208 receives control commands from the CPU 201 and outputs commands to the spindle amplifier 6 for driving the spindle motor 7. For example, the spindle control circuit 208 sends a torque command to the spindle amplifier 6 to control the torque of the spindle motor 7.

[0045] The spindle amplifier 6 receives instructions from the spindle control circuit 208 and supplies current to the spindle motor 7. The spindle amplifier 6 has a built-in ammeter 61 for measuring the current value supplied to the spindle motor 7.

[0046] Ammeter 61 detects the current value supplied to the spindle motor 7. Ammeter 61 sends data representing the detected current value to CPU 201.

[0047] The spindle motor 7 is driven by receiving current from the spindle amplifier 6. The spindle motor 7 is connected to the spindle, causing the spindle to rotate.

[0048] PLC 209 is a device that executes ladder logic programs to control auxiliary equipment 8. PLC 209 sends instructions to auxiliary equipment 8 via I / O unit 210.

[0049] I / O unit 210 is the interface connecting PLC 209 and auxiliary device 8. I / O unit 210 sends instructions received from PLC 209 to auxiliary device 8.

[0050] Auxiliary device 8 is installed on machine tool 1 and performs auxiliary actions on machine tool 1. Auxiliary device 8 operates based on instructions received from I / O unit 210. Auxiliary device 8 can also be a device located around machine tool 1. Auxiliary device 8 is, for example, a tool changing device, a coolant spraying device, or a door opening / closing drive device.

[0051] Next, an example of the function of the numerical control device 2 will be explained. The numerical control device 2 detects the load applied to the spindle when machining a workpiece at a feed rate specified by the machining program. Furthermore, based on the detected load data applied to the spindle, the numerical control device 2 predicts the machining time if the workpiece is machined with the load applied to the spindle reaching the target load.

[0052] Figure 2 This is a block diagram illustrating an example of the function of the numerical control device 2. The numerical control device 2 includes a program storage unit 211, a control unit 212, a spindle load detection unit 213, a spindle load storage unit 214, a target load receiving unit 215, a target load setting unit 216, a machining time prediction unit 217, and a machining time output unit 218.

[0053] The program storage unit 211 and the spindle load storage unit 214 are implemented by storing the machining program input from the input / output device 3 and the data input from the ammeter 61 and various sensors in RAM 204 or non-volatile memory 205.

[0054] The control unit 212, spindle load detection unit 213, target load receiving unit 215, target load setting unit 216, machining time prediction unit 217, and machining time output unit 218 are implemented, for example, by CPU 201 using the system program stored in ROM 203 and the machining program and various data stored in non-volatile memory 205 for calculation and processing.

[0055] The program storage unit 211 stores the machining program. The machining program is used to cause the various parts of the machine tool 1 to move to machine the workpiece. In the machining program, G codes and M codes are used to indicate the tool's movement path, tool feed rate, and spindle rotation speed, etc.

[0056] The control unit 212 controls various parts of the machine tool 1 based on the machining program. For example, the control unit 212 controls the servo motor 5 and the spindle motor 7.

[0057] The control unit 212 performs constant speed control based on the machining program. Constant speed control refers to the control that moves the spindle at a feed rate specified by the machining program.

[0058] Furthermore, the control unit 212 performs constant load control based on the machining program. Constant load control refers to the control that varies the spindle feed speed specified by the machining program so that the load applied to the spindle becomes the load set by the target load setting unit 216. In constant load control, compared with constant speed control, it is possible to suppress variations in the load applied to the spindle.

[0059] The spindle load detection unit 213 detects timing data of the load applied to the spindle during workpiece machining based on the machining program. Additionally, the spindle load detection unit 213 detects timing data representing the spindle feed rate. In other words, during workpiece machining based on the machining program, the spindle load detection unit 213 detects the load applied to the spindle and the spindle feed rate at predetermined intervals.

[0060] The spindle load detection unit 213 detects the load applied to the spindle, for example, based on the current value indicated by the ammeter 61 built into the spindle amplifier 6. Additionally, the spindle load detection unit 213 detects the spindle feed speed based on data detected by the speed detector built into the servo motor 5. Furthermore, the load applied to the spindle refers to the load torque applied in the opposite direction to the spindle's rotational direction.

[0061] The spindle load storage unit 214 stores timing data of the load applied to the spindle detected by the spindle load detection unit 213. That is, the spindle load storage unit 214 stores timing data representing the load applied to the spindle during workpiece machining. Additionally, the spindle load storage unit 214 stores timing data representing the spindle feed rate during workpiece machining. The timing data stored in the spindle load storage unit 214 is timing data detected during constant-speed control of the spindle based on the machining program.

[0062] Figure 3 This diagram illustrates an example of timing data stored in the spindle load storage unit 214. That is, Figure 3 The timing data shown is the data detected during processing with constant speed control. Figure 3The spindle load storage unit 214 is shown to sequentially store timing data L, 2L, 3L, 4L, 3L, 2L and L representing the load detected according to a predetermined period T.

[0063] Here, return Figure 2 Explanation.

[0064] The target load receiving unit 215 accepts input representing the value of the target load applied to the spindle during constant load control. For example, the target load receiving unit 215 accepts a value input by the operator using the input / output device 3. For example, the operator uses the input / output device 3 to input the target load applied to the spindle during workpiece machining under constant load control.

[0065] The target load setting unit 216 sets the target load applied to the spindle, which is received by the target load receiving unit 215. The target load setting unit 216 sets the target load, for example, by storing data representing the target load in a pre-determined register (not shown).

[0066] The machining time prediction unit 217 predicts the machining time based on timing data stored in the spindle load storage unit 214, assuming the spindle feed speed is controlled such that the load applied to the spindle becomes the target load. In other words, the machining time predicted by the machining time prediction unit 217 is the machining time under constant load control when the machining program executed upon acquiring the timing data stored in the spindle load storage unit 214 is executed. In other words, the machining time prediction unit 217 predicts the machining time when the machining program is executed with the target load set by the target load setting unit 216 applied to the spindle, based on timing data detected during constant speed control. The machining time prediction unit 217 assumes that the load applied to the spindle is proportional to the spindle feed speed when predicting the machining time.

[0067] Figures 4A-4D as well as Figure 5 This diagram illustrates the method by which the machining time prediction unit 217 predicts machining time. The machining time prediction unit 217 first reads the timing data of the load applied to the spindle, stored in the spindle load storage unit 214. This timing data indicates that the load applied to the spindle is data detected every predetermined cycle T.

[0068] Next, the machining time prediction unit 217 calculates the machining time when the load applied to the spindle in each cycle T is changed to the target load for machining.

[0069] For example, to change the load L to the target load 2L while maintaining a proportional relationship between the load applied to the spindle and the spindle feed rate, the spindle feed rate needs to be doubled. In this case, the machining time for processing the range where the load L is detected is T / 2 (refer to...). Figure 4ASince the load in the 2L load range is the same as the target load, the spindle feed rate remains unchanged. That is, the machining time T remains unchanged (refer to...). Figure 4B ).

[0070] When the load in the zone where the detected load is 3L is changed to 2L, the processing time for that zone is 3T / 2 (refer to...). Figure 4C Similarly, when the load in the section where the detected load is 4L is changed to 2L, the processing time for processing that section is 2T (refer to...). Figure 4D ).

[0071] Next, the machining time prediction unit 217 calculates the machining time when the load applied to the spindle in each cycle T is changed to the target load (see reference). Figure 5 Therefore, the machining time prediction unit 217 can predict the machining time when a constant load control is performed with the load applied to the spindle becoming the target load. Furthermore, the machining time prediction unit 217 can also predict the feed rate in each cycle when the feed rate is controlled such that the load applied to the spindle becomes the target load.

[0072] The machining time output unit 218 outputs data representing the machining time predicted by the machining time prediction unit 217. For example, the machining time output unit 218 outputs data representing the machining time and data representing the target load to the input / output device 3, causing the input / output device 3 to display the machining time and the target load. The machining time output unit 218 can also output the spindle feed rate calculated during the machining time prediction process by the machining time prediction unit 217. In this case, the machining time output unit 218 can also output data representing the spindle feed rate, so that the spindle feed rate for each cycle T is displayed in a graph.

[0073] Furthermore, the control unit 212 can also execute a machining program under constant load control to machine the workpiece, so that the target load received by the target load receiving unit 215 is applied to the spindle. In this case, the workpiece can be machined at the machining time predicted by the machining time prediction unit 217, or a machining time approximately thereafter.

[0074] Next, the process flow of the numerical control device 2 will be explained.

[0075] Figure 6 This is a flowchart illustrating an example of the processing flow performed by the numerical control device 2. First, the spindle load detection unit 213 detects timing data representing the load applied to the spindle during workpiece machining under constant speed control, based on the machining program (step S1).

[0076] Next, the spindle load storage unit 214 stores timing data representing the load applied to the spindle detected by the spindle load detection unit 213 (step S2).

[0077] Next, the target load receiving unit 215 receives an input indicating the value of the target load applied to the spindle (step S3).

[0078] Next, the target load setting unit 216 sets the target load received by the target load receiving unit 215 (step S4).

[0079] Next, the machining time prediction unit 217 predicts the machining time when the spindle feed speed is controlled in such a way that the load applied to the spindle becomes the target load (step S5).

[0080] Finally, the processing time output unit 218 outputs data representing the processing time predicted by the processing time prediction unit 217 (step S6), and the process ends.

[0081] As explained above, the numerical control device 2 includes: a spindle load detection unit 213 that detects timing data of the load applied to the spindle during workpiece machining; a target load setting unit 216 that sets a target load applied to the spindle; a machining time prediction unit 217 that predicts the machining time based on the timing data when the spindle feed speed is controlled such that the load applied to the spindle becomes the target load; and a machining time output unit 218 that outputs the predicted machining time data. Thus, the numerical control device 2 can output the machining time when the spindle feed speed is controlled such that the target load is applied to the spindle. As a result, the operator can determine the load applied to the spindle by considering the output machining time. For example, the operator can determine the load applied to the spindle to achieve a machining time that matches the cycle time of the previous machining operation.

[0082] Furthermore, the numerical control device 2 also includes a target load receiving unit 215 that receives input representing the value of the target load set by the target load setting unit 216. Therefore, the numerical control device 2 can predict the processing time based on the input target load.

[0083] Furthermore, the machining time prediction unit 217 predicts the machining time by assuming that the load applied to the spindle is proportional to the feed rate. Therefore, the machining time prediction unit 217 can predict the machining time without performing complex calculations.

[0084] Furthermore, the machining time prediction unit 217 also predicts the feed rate when the spindle feed rate is controlled such that the load applied to the spindle becomes the target load. Thus, the operator can determine whether the spindle feed rate is suitable for machining the workpiece and set the target load accordingly.

[0085] In addition, the numerical control device 2 also includes a spindle load storage unit 214 for storing timing data detected by the spindle load detection unit 213. As a result, the machining time prediction unit 217 can predict the machining time multiple times based on various target loads received by the target load receiving unit 215.

[0086] In the described embodiment, the machining time prediction unit 217 assumes that the load applied to the spindle is proportional to the spindle feed rate and predicts the machining time accordingly. However, the machining time prediction unit 217 may also predict the machining time based on a correlation model representing the relationship between the load applied to the spindle and the spindle feed rate.

[0087] Figure 7 This diagram illustrates an example of the processing time prediction unit 217. The processing time prediction unit 217 includes a learning unit 221, a related model storage unit 222, and a prediction unit 223. Furthermore, the structure other than the processing time prediction unit 217 is the same as that of the embodiment described above.

[0088] The learning unit 221 generates a correlation model representing the relationship between the applied spindle load and the spindle feed rate based on the time-series data representing the load applied to the spindle and the time-series data representing the spindle feed rate stored in the spindle load storage unit 214. The learning unit 221 generates the correlation model, for example, using regression, SVM (Support Vector Machine), or neural networks.

[0089] The related model storage unit 222 stores the related models generated by the learning unit 221.

[0090] The prediction unit 223 uses the correlation model stored in the correlation model storage unit 222 to predict the machining time when the spindle is controlled in such a way that the load applied to the spindle becomes the target load. In addition, the prediction unit 223 can also use the correlation model to predict the spindle feed rate when the spindle is controlled in such a way that the load applied to the spindle becomes the target load.

[0091] The data representing the processing time predicted by the prediction unit 223 is output by the processing time output unit 218.

[0092] In the described embodiment, the machining time prediction unit 217 further includes a learning unit 221 that learns the relationship between the load applied to the spindle and the feed rate. The machining time prediction unit 217 predicts the machining time based on the relationship learned by the learning unit 221. Therefore, the machining time prediction unit 217 can predict the machining time with high accuracy.

[0093] Furthermore, the target load receiving unit 215 can also accept, for example, a value representing the ratio of the target torque to the rated torque as a value representing the target load applied to the spindle. For example, by accepting input values ​​such as 50%, 55%, 60%, or 65%, the target load can be set.

[0094] Furthermore, the numerical control device 2 in the described embodiment includes a target load receiving unit 215, but the numerical control device 2 may not necessarily include a target load receiving unit 215. In this case, the numerical control device 2 can pre-store values ​​representing multiple target loads and predict the processing time for each process when constant load control is performed by applying multiple target loads to the spindle respectively.

[0095] Figure 8 This diagram illustrates an example of a processing time display on the input / output device 3 when processing time is predicted for multiple target loads. In the numerical control device 2, for example, a value representing the ratio of the target torque to the rated torque is pre-stored as the target load. Figure 8 In the example shown, 50%, 53%, 56%, 59%, 62%, 65%, 68%, and 71% are stored as target loads.

[0096] The machining time prediction unit 217 predicts the machining time for each spindle under constant load control, where these target loads are applied to the spindle respectively. Data representing the machining time predicted by the machining time prediction unit 217 is output by the machining time output unit 218 and displayed on the display screen of the input / output device 3.

[0097] The display screen may show, for example, a graduated straight line extending horizontally. Above this line, as the target load, a value representing the ratio of the target torque to the rated torque is displayed.

[0098] The predicted processing time corresponding to each target load is displayed below the straight line. For example, processing time 11:00 is displayed corresponding to 50% of the target load. Processing time 10:30 is displayed corresponding to 53% of the target load. Processing time 10:00 is displayed corresponding to 56% of the target load. Processing time 9:30 is displayed corresponding to 59% of the target load. Processing time 9:00 is displayed corresponding to 62% of the target load. Processing time 8:00 is displayed corresponding to 65% of the target load. Processing time 7:00 is displayed corresponding to 68% of the target load. Processing time 6:00 is displayed corresponding to 71% of the target load.

[0099] By displaying the machining time in this way, the operator can easily grasp the individual machining time under the condition of controlling the spindle by applying various loads.

[0100] Furthermore, the processing time can also be displayed below the area displaying each processing time as a proportion of the processing time under constant load control relative to the processing time executed under constant speed control. For example, in Figure 8 In the example shown, the processing time under constant speed control is 10:00. The proportion of the processing time under constant load control for each target load is shown in parentheses relative to this processing time.

[0101] In addition, such as Figure 8 As shown, when the target load and the corresponding machining time are displayed in an orderly fashion on the input / output device 3, any target load can also be selected on the display screen. In this case, the workpiece can be machined under constant load control by applying the selected target load to the spindle.

[0102] In the described embodiment, the numerical control device 2 includes a spindle load storage unit 214. However, the numerical control device 2 may not necessarily include a spindle load storage unit 214.

[0103] Figure 9 This is a block diagram illustrating an example of the function of the numerical control device 2. The numerical control device 2 replaces the spindle load storage unit 214 with a generation unit 224 and a frequency distribution storage unit 225. Other structures are similar to... Figure 2 The numerical control device 2 shown has the same structure.

[0104] The generation unit 224 is implemented, for example, by CPU 201 using a system program stored in ROM 203 and a processing program stored in non-volatile memory 205, as well as various data, for calculation and processing. The frequency distribution storage unit 225 is implemented, for example, by CPU 201 using a system program and various data for calculation and processing, and storing the generated data in RAM 204 or non-volatile memory 205.

[0105] The generation unit 224 generates frequency distribution data based on the timing data detected by the spindle load detection unit 213.

[0106] Figure 10 This is a graph showing the timing data of the load applied to the spindle, detected by the spindle load detection unit 213. That is, Figure 10 The timing data shown is the data detected during processing with constant speed control. Figure 11This is a diagram illustrating an example of frequency distribution. The generation unit 224 distributes the load applied to the spindle, detected by the spindle load detection unit 213, to multiple levels, and counts the frequency of each level. For example, the generation unit 224 assigns the detected load to one of four levels: L, 2L, 3L, and 4L. Alternatively, the generation unit 224 may round the load value detected by the spindle load detection unit 213 and assign it to one of the levels: L, 2L, 3L, and 4L.

[0107] The generating unit 224, for example, assigns loads of 0.5L or more but less than 1.5L to class L. Similarly, the generating unit 224 assigns loads of 1.5L or more but less than 2.5L to class 2L. Similarly, it assigns loads of 2.5L or more but less than 3.5L to class 3L. Similarly, the generating unit 224 assigns loads of 3.5L or more but less than 4.5L to class 4L. Figure 11 In the example shown, four load data points are assigned to level L, five load data points are assigned to level 2L, two load data points are assigned to level 3L, and one load data point is assigned to level 4L.

[0108] The frequency distribution storage unit 225 stores the frequency distribution data generated by the generation unit 224.

[0109] The processing time prediction unit 217 predicts processing time based on frequency distribution data stored in the frequency distribution storage unit 225. The processing time prediction unit 217 calculates the processing time when processing is performed by changing the load represented by each level to the target load, and calculates the processing time by adding the processing times of each level. The processing time T for each level L, 2L, 3L, and 4L is... L T 2L T 3L And T 4L These can be calculated using (frequency) × (level value) × (cycle) / (target load).

[0110] For example, for Figure 11 The processing time T calculated from grade L is shown. L For T L = 4 × L × T / 2L = 2T. Similarly, the processing time T calculated for level 2L is... 2L For T 2L =5 × 2L × T / 2L = 5T. Similarly, the processing time T calculated for level 3L is... 3L For T 3L = 2 × 3L × T / 2L = 3T. Similarly, the processing time T calculated for level 4L is... 4L For T 4L=1×4L×T / 2L=2T. The total processing time of 12T is obtained by summing the processing times calculated for each level.

[0111] In the described embodiment, the numerical control device 2 further includes a frequency distribution storage unit 225, which stores data representing the frequency distribution generated based on the timing data detected by the spindle load detection unit 213. Therefore, compared to the case where the spindle load storage unit 214 stores timing data, the amount of data stored can be reduced.

[0112] Furthermore, the processing time calculated for each level does not have to follow the order described above. For example, the processing time can be calculated by multiplying the total (frequency) × (level value) calculated for each level by (cycle) / (target load).

[0113] Explanation of reference numerals in the attached figures

[0114] 1. Machine tools

[0115] 2. Numerical control device

[0116] 201 CPU

[0117] 202 bus,

[0118] 203ROM

[0119] 204 RAM

[0120] 205 non-volatile memory,

[0121] 206 interface

[0122] 207-axis control circuit

[0123] 208 spindle control circuit

[0124] 209 PLC

[0125] 210 I / O unit,

[0126] 211 Program Storage Department

[0127] 212 Control Department

[0128] 213 Spindle Load Detection Unit

[0129] 214 Spindle Load Storage Unit

[0130] 215 Target Load Receiving Unit

[0131] 216 Target Load Setting Unit

[0132] 217 Processing Time Prediction Department

[0133] 218 Processing Time Output Section

[0134] 221 Study Department

[0135] 222 Related Model Storage Department

[0136] 223 Forecasting Department

[0137] 224 Production Department

[0138] 225 frequency distribution storage unit,

[0139] 3 Input / output devices

[0140] 4 Servo amplifiers

[0141] 5 servo motors,

[0142] 6. Spindle amplifier

[0143] 61 Ammeter

[0144] 7. Spindle motor

[0145] 8. Auxiliary equipment.

Claims

1. A numerical control device, characterized in that, This numerical control device has the following features: The spindle load detection unit detects the timing data of the load applied to the spindle during workpiece machining; A target load setting unit, which sets the target load to be applied to the spindle; A machining time prediction unit, based on the timing data, predicts the machining time when the feed rate of the spindle is controlled such that the load applied to the spindle becomes the target load; and The processing time output unit outputs the predicted processing time data. The machining time prediction unit assumes that the load applied to the spindle is proportional to the feed rate and calculates the feed rate based on the target load, and predicts the machining time based on the calculated feed rate.

2. The numerical control device according to claim 1, characterized in that, The numerical control device also includes a target load receiving unit that accepts an input representing the value of the target load set by the target load setting unit.

3. The numerical control device according to claim 1 or 2, characterized in that, The processing time output unit also outputs data representing the relationship between the target load and the predicted processing time.

4. The numerical control device according to any one of claims 1 to 3, characterized in that, The machining time prediction unit also predicts the feed rate when the feed rate is controlled such that the load applied to the spindle becomes the target load.

5. The numerical control device according to any one of claims 1 to 4, characterized in that, The numerical control device also includes a spindle load storage unit for storing the timing data detected by the spindle load detection unit.

6. The numerical control device according to any one of claims 1 to 5, characterized in that, The numerical control device also includes a frequency distribution storage unit that stores frequency distribution data generated based on the timing data detected by the spindle load detection unit.

7. A computer-readable storage medium, characterized in that, Store the commands that enable the computer to perform the following processes: The timing data of the load applied to the spindle during workpiece machining is detected. Set the target load to be applied to the spindle; Based on the time-series data, the machining time is predicted when the spindle feed rate is controlled in such a way that the load applied to the spindle becomes the target load; and Output the predicted processing time data. The storage medium also stores commands that cause the computer to perform the following processes: The feed rate is calculated based on the target load, assuming that the load applied to the spindle is proportional to the feed rate, and the machining time is predicted based on the calculated feed rate.

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