Tool damage detection device and computer-readable storage medium

Abstract

The tool damage detection device includes a data acquisition unit that acquires load data representing a load of a spindle in a cutting feed interval and rotation speed data representing a rotation speed of the spindle; an extraction unit that extracts, from the load data, evaluation data used in evaluation of occurrence of damage of a tool, based on the rotation speed data; a detection unit that detects occurrence of the damage of the tool using the evaluation data; and an output unit that outputs data representing the occurrence of the damage of the tool in a case where the damage of the tool is detected by the detection unit.

Description

Technical Field

[0001] This invention relates to a tool damage detection device and a computer-readable storage medium. Background Technology

[0002] Conventionally, tool damage detection is performed in machine tools. In this case, for example, time-series data representing the load applied to the spindle during the interval from the start of tool rotation to its stop is acquired. Then, the acquired time-series data within that interval is compared with reference time-series data to detect tool damage (e.g., Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 52-95386 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, for example, in the case of tapping, the load data obtained from the beginning to the end of the machining cycle sometimes includes data on periods when the load changes significantly due to acceleration and deceleration torque, as well as data representing the load during non-cutting operations.

[0008] In this case, the obtained load data does not accurately represent the load applied to the spindle during the actual cutting process. Therefore, even if such load data is used for tool damage detection, it may not be possible to detect tool damage with high precision.

[0009] The purpose of this invention is to reliably detect tool damage by accurately capturing the characteristics of the load applied to the spindle.

[0010] Methods for solving problems

[0011] The tool damage detection device includes: a data acquisition unit that acquires load data representing the spindle load in the cutting feed range and rotational speed data representing the spindle rotational speed; an extraction unit that extracts evaluation data used in evaluating the occurrence of tool damage from the load data based on the rotational speed data; a detection unit that uses the evaluation data to detect the occurrence of tool damage; and an output unit that outputs data representing the occurrence of tool damage when the detection unit detects tool damage.

[0012] The computer-readable storage medium stores commands that enable the computer to perform the following steps: acquire load data representing the spindle load in the cutting feed range and rotational speed data representing the spindle rotational speed; extract evaluation data from the load data based on the rotational speed data, which is used in evaluating the occurrence of tool damage; use the evaluation data to detect the occurrence of tool damage; and, if tool damage is detected, output data representing the occurrence of tool damage.

[0013] Invention Effects

[0014] According to the present invention, tool damage can be reliably detected by accurately capturing the characteristics of the load applied to the spindle. Attached Figure Description

[0015] Figure 1 This is a diagram illustrating an example of the hardware structure of a machine tool.

[0016] Figure 2 This is a block diagram illustrating an example of the function of a numerical control device.

[0017] Figure 3 This is a diagram showing an example of the data acquired by the data acquisition unit during the tapping process.

[0018] Figure 4 This is a diagram showing an example of the data acquired by the data acquisition unit during milling.

[0019] Figure 5 This is a diagram showing an example of the data acquired by the data acquisition unit during drilling.

[0020] Figure 6 This is a flowchart illustrating an example of a processing flow executed in a numerical control device.

[0021] Figure 7 This is a flowchart illustrating an example of a processing flow performed in a numerical control device. Detailed Implementation

[0022] Hereinafter, an embodiment of the present invention will be described using the accompanying drawings. Furthermore, not all combinations of the features described in the following embodiments are necessary to solve the problem. Additionally, necessary detailed descriptions are sometimes omitted. Moreover, the following description of the embodiments and the accompanying drawings are provided to enable those skilled in the art to fully understand the present invention and are not intended to limit the scope of the claimed patent protection.

[0023] A tool damage detection device is a device used to detect tool damage during or after machine tool operation. Tool damage includes, for example, tool breakage or breakage.

[0024] Tool damage detection devices can be, for example, numerical control devices for machine tools. Alternatively, tool damage detection devices can also be computers such as management servers that manage the operating status of machine tools. The following will illustrate an example where the tool damage detection device is a numerical control device.

[0025] Figure 1 This is a diagram illustrating an example of the hardware structure of a machine tool. Machine tool 1 is, for example, a machining center, a multi-function machining center, a drilling machine, or a tapping center. Machine tool 1 includes a numerical control device 2, a display device 3, an input device 4, a servo amplifier 5 and a servo motor 6, a spindle amplifier 7 and a spindle motor 8, and auxiliary equipment 9.

[0026] The numerical control device 2 is a device that controls the entire machine tool 1. The numerical control device 2 includes a CPU 201, a bus 202, a ROM 203, a RAM 204, and a non-volatile memory 205.

[0027] 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 6 and spindle motor 8 according to the machining program.

[0028] 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.

[0029] ROM203 is a storage device or storage medium that stores system programs and other data used to control the numerical control device 2 as a whole.

[0030] RAM204 is a storage device for temporary storage of various data. RAM204 functions as a working area for CPU201 to process various data.

[0031] 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 is, for example, an SSD (Solid State Drive).

[0032] The numerical control device 2 also includes a first interface 206, a second interface 207, an axis control circuit 208, a spindle control circuit 209, a PLC (Programmable Logic Controller) 210, and an I / O unit 211.

[0033] The first interface 206 is an interface connecting the bus 202 and the display device 3. For example, the first interface 206 sends various data processed by the CPU 201 to the display device 3.

[0034] Display device 3 is a device that receives and displays various data via the first interface 206. Display device 3 is a display such as LCD (Liquid Crystal Display).

[0035] The second interface 207 is an interface connecting the bus 202 and the input device 4. For example, the second interface 207 sends data input from the input device 4 to the CPU 201 via the bus 202.

[0036] Input device 4 is a device for inputting various types of data. Input device 4 is, for example, a keyboard and a mouse. In addition, input device 4 and display device 3 can also be configured as a single device, such as a touch panel.

[0037] The axis control circuit 208 is a circuit that controls the servo motor 6. The axis control circuit 208 receives control commands from the CPU 201 and outputs commands for driving the servo motor 6 to the servo amplifier 5. For example, the axis control circuit 208 sends torque commands that control the torque of the servo motor 6 to the servo amplifier 5.

[0038] Servo amplifier 5 receives instructions from axis control circuit 208 and supplies current to servo motor 6.

[0039] The servo motor 6 is driven by receiving current from the servo amplifier 5. The servo motor 6 is connected, for example, to a ball screw that drives the tool post, spindle head, and worktable. By driving the servo motor 6, the machine tool 1's structures, such as the tool post, spindle head, and worktable, move, for example, in the X-axis, Y-axis, or Z-axis direction.

[0040] The spindle control circuit 209 is used to control the spindle motor 8. The spindle control circuit 209 receives control commands from the CPU 201 and outputs commands to the spindle amplifier 7 for driving the spindle motor 8. For example, the spindle control circuit 209 sends a torque command to the spindle amplifier 7 to control the torque of the spindle motor 8.

[0041] The spindle amplifier 7 receives instructions from the spindle control circuit 209 and supplies current to the spindle motor 8. The spindle amplifier 7 has a built-in ammeter 71, which measures the current value supplied to the spindle motor 8.

[0042] Ammeter 71 measures the current value supplied to the spindle motor 8. The current value measured by ammeter 71 is used for spindle load detection.

[0043] The spindle motor 8 is driven by receiving current from the spindle amplifier 7. The spindle motor 8 is connected to the spindle, causing the spindle to rotate. The spindle motor 8 is equipped with a speed detector 81 that detects the rotational speed of the spindle motor 8.

[0044] Speed ​​detector 81 detects the rotational speed of spindle motor 8. Data representing the rotational speed of spindle motor 8 detected by speed detector 81 is used to extract baseline load data and evaluation data for detecting tool damage. The baseline load data and evaluation data will be explained in detail later.

[0045] PLC210 is a device that executes ladder logic programs to control auxiliary equipment 9. PLC210 controls auxiliary equipment 9 via I / O unit 211.

[0046] I / O unit 211 is the interface connecting PLC 210 and auxiliary device 9. I / O unit 211 sends the instructions received from PLC 210 to auxiliary device 9.

[0047] Auxiliary equipment 9 is installed on machine tool 1 to perform auxiliary actions when machine tool 1 processes workpieces. Auxiliary equipment 9 can also be a device installed around machine tool 1. Auxiliary equipment 9 is, for example, a tool changing device, a coolant spraying device, or a door opening / closing drive device.

[0048] Next, an example of the function of the numerical control device 2 will be explained.

[0049] 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 control unit 221, a data acquisition unit 222, an extraction unit 223, a storage unit 224, a detection unit 225, and an output unit 226.

[0050] The control unit 221, data acquisition unit 222, extraction unit 223, detection unit 225, and output unit 226 are implemented, for example, by the CPU 201 performing calculations using system programs and various data stored in the ROM 203. The CPU 201 uses the RAM 204 as its operating area to perform the calculations. The storage unit 224 is implemented by storing data input from the input device 4, etc., or the calculation results of the CPU 201 in the RAM 204 or non-volatile memory 205.

[0051] The control unit 221 controls all parts of the machine tool 1. Additionally, the control unit 221 reads and parses the machining program. The control unit 221 executes the parsed machining program to control the servo motor 6 and the spindle motor 8. Thus, workpiece machining is performed. Furthermore, the control unit 221 controls the operation of auxiliary equipment 9, etc.

[0052] The data acquisition unit 222 acquires load data representing the spindle load in the cutting feed range and rotation speed data representing the spindle rotation speed.

[0053] The cutting feed range refers to the range in which the tool moves by means of the cutting feed. This range can be, for example, the range in which the tool moves by means of the linear interpolation command "G01", circular interpolation command "G02", or "G03" specified in the machining program. That is, the cutting feed range does not include the rapid traverse range where the tool moves quickly. During the cutting feed range, a cutting signal is output to the numerical control device 2. This cutting signal can be, for example, a speed control signal used by the control unit 221 to control the speed of the servo motor.

[0054] The load data representing the spindle load is time-series data representing the load applied in the spindle's rotational direction. The load data can be represented, for example, by the current value supplied to the spindle motor 8. Alternatively, the load data can be time-series data representing the value measured by the ammeter 71 built into the spindle amplifier 7. Alternatively, the load data can also be time-series data representing the value of the electrical power supplied to the spindle motor 8. For example, load data is acquired every 1 ms.

[0055] The rotational speed data, representing the spindle's rotational speed, is time-series data representing the spindle's rotational speed. For example, the rotational speed data is time-series data of values ​​detected by the speed detector 81 installed on the spindle motor 8. When the spindle rotates forward, the rotational speed data represents a positive value. When the spindle rotates in reverse, the rotational speed data represents a negative value. For example, the rotational speed data is obtained every 1 [ms].

[0056] The data acquisition unit 222 acquires load data and rotational speed data, for example, during the initial machining of a workpiece using a normal tool, and during the machining of the workpiece a second time or thereafter. A normal tool refers to a tool that does not experience wear or damage.

[0057] The extraction unit 223 extracts reference load data, which serves as a benchmark for detecting tool damage, based on the load data and rotational speed data obtained during the initial machining of the workpiece using a normal tool. Additionally, the extraction unit 223 extracts evaluation data used in assessing tool damage occurrence, based on the load data and rotational speed data obtained during subsequent machining operations.

[0058] The extraction unit 223 extracts load data as evaluation data for the section of the cutting feed range where the spindle rotates forward and the rotational speed is constant. Here, "constant" means approximately constant; for example, even if the rotational speed varies slightly during cutting, it is considered to be a constant rotational speed.

[0059] Extraction unit 223, for example, extracts the spindle at a rotational speed of ±10 [min] as instructed by the machining program. -1 The load data of the rotating interval is used as the benchmark load data or evaluation data.

[0060] Figure 3 This diagram shows an example of the data acquired by the data acquisition unit 222 during the tapping process. Figure 3 (1) shows data representing signals during cutting. Figure 3 (2) shows the rotational speed data. Figure 3 (3) shows the load data obtained when the initial workpiece is machined using normal tools. Figure 3 (4) shows the load data obtained under the condition of tap breakage.

[0061] Tapping is performed using tapping cycle commands. In a tapping cycle, when a cutting signal is output, the spindle begins to rotate, and the tool moves in the negative Z-axis direction in accordance with the thread pitch.

[0062] After the spindle begins to rotate, during the period until the rotational speed reaches the commanded speed ( Figure 3 In the a1 interval of (2), the rotational speed increases sharply. That is, in this interval, the rotational speed of the spindle is not constant, so the extraction unit 223 does not extract the load data of this interval as reference load data or evaluation data. In addition, after the spindle starts rotating, during the period until the rotational speed reaches the commanded speed, the load applied to the rotational direction of the spindle due to acceleration and deceleration torque changes significantly.

[0063] Once the spindle reaches the commanded speed, its rotational speed remains constant. Figure 3 (2) b1 interval). Therefore, the extraction unit 223 extracts the load data of this interval as reference load data or evaluation data. In addition, when the tap contacts the workpiece and performs cutting, the load applied to the spindle increases.

[0064] When the tool reaches the depth of the hole and the spindle rotates in the opposite direction ( Figure 3 In the c1 interval of (2), the spindle speed drops sharply from the commanded speed. That is, the spindle speed is not constant in this interval, so the extraction unit 223 does not extract the load data of this interval as reference load data or evaluation data. In addition, when the spindle rotation direction is reversed, the load applied to the spindle rotation direction due to acceleration and deceleration torque changes drastically.

[0065] When the tool returns to the cutting start position and the spindle stops ( Figure 3In the (2)e1 interval), the spindle rotation speed also increases sharply. That is, in this interval, the spindle rotation speed is not constant, so the extraction unit 223 does not extract the load data of this interval as reference load data or evaluation data. In addition, when the tool returns to the cutting start position and the spindle stops, the load applied to the spindle rotation direction due to acceleration and deceleration torque changes significantly.

[0066] During the spindle reversal ( Figure 3 In the d1 interval of (2), the spindle rotation speed is negative. Therefore, the extraction unit 223 does not extract the load data in this interval as reference load data or evaluation data. In addition, the period during which the tool returns to the cutting start position along the machining path while the spindle reverses is a non-cutting state.

[0067] As mentioned above, Figure 3 (3) represents the load data obtained during the initial machining of the workpiece. Therefore, from Figure 3 The load data shown in (3) is the baseline load data. The evaluation data extracted from the start of workpiece machining after the second time until tool damage occurs becomes the baseline load data. Figure 3 The load data shown in (3) is roughly the same.

[0068] As mentioned above, Figure 3 (4) represents the load data obtained when the tap is broken. That is, from Figure 3 The load data shown in (4) is the evaluation data when tool damage occurs.

[0069] Figure 4 This is a diagram showing an example of the data acquired by the data acquisition unit 222 during milling. Figure 4 (1) shows data representing signals during cutting. Figure 4 (2) shows the rotational speed data. Figure 4 (3) shows the load data obtained during the initial machining of the workpiece. Figure 4 (4) shows the load data obtained under the condition of milling cutter breakage.

[0070] like Figure 4 As shown, the range from the start of spindle rotation to reaching the commanded speed ( Figure 4 (2) a2 interval), and the interval from the state of the spindle rotating at the commanded speed to the point of stopping ( Figure 4 (2) b2 interval is not included in the cutting feed interval in milling. In addition, the spindle does not reverse in milling.

[0071] That is, during milling, the spindle rotates clockwise within the cutting feed interval, and the spindle speed is fixed. Therefore, the extraction unit 223 extracts the entire cutting feed interval as reference load data or evaluation data.

[0072] As mentioned above, Figure 4 (3) shows the load data during the initial workpiece machining. That is, from Figure 4 The load data extracted as shown in (3) is the baseline load data. Additionally, the evaluation data extracted from the start of workpiece machining after the second machining session until tool damage occurs becomes the baseline load data. Figure 4 The load data shown in (3) is roughly the same.

[0073] As mentioned above, Figure 4 (4) shows the load data obtained with the milling cutter broken. That is, from Figure 4 The load data shown in (4) is the evaluation data when tool damage occurs.

[0074] Figure 5 This diagram illustrates an example of the data acquired by the data acquisition unit 222 during drilling. Figure 5 (1) shows data representing signals during cutting. Figure 5 (2) shows the rotational speed data. Figure 5 (3) shows the load data obtained during the initial workpiece machining. Figure 5 (4) shows the load data obtained under the condition of drill bit breakage.

[0075] like Figure 5 As shown, the range from the start of spindle rotation to reaching the commanded speed ( Figure 5 (2) a3 interval), and the interval from the state of the spindle rotating at the commanded speed to the stop ( Figure 5 (2) b3 interval) is not included in the cutting feed interval in drilling. In addition, the spindle does not reverse during drilling.

[0076] That is, during drilling, the spindle rotates clockwise within the cutting feed interval, and the spindle speed is fixed. Therefore, the extraction unit 223 extracts the entire cutting feed interval as reference load data or evaluation data.

[0077] As mentioned above, Figure 5 (3) shows the load data during the initial workpiece machining. That is, from Figure 5 The load data extracted as shown in (3) is the baseline load data. Additionally, the evaluation data extracted from the start of workpiece machining after the second machining session until tool damage occurs becomes the baseline load data. Figure 5The load data shown in (3) is roughly the same.

[0078] As mentioned above, Figure 5 (4) shows the load data obtained under the condition of drill bit breakage. That is, from Figure 5 The load data shown in (4) is the evaluation data when tool damage occurs.

[0079] Here, we will continue to explain. Figure 2 The function of numerical control device 2.

[0080] Storage unit 224 stores the reference load data and evaluation data extracted by extraction unit 223. Storage unit 224 stores the reference load data and evaluation data, for example, in association with time information. The time information is, for example, information representing the time from the start of the machining process execution to the acquisition of the extracted load data as reference load data or evaluation data.

[0081] The detection unit 225 uses evaluation data to detect the occurrence of tool damage. The detection unit 225 detects tool damage based on baseline load data and evaluation data stored in the storage unit 224. For example, the detection unit 225 detects tool damage by comparing the baseline load data and the evaluation data. For example, the detection unit 225 determines the evaluation data and the corresponding baseline load data based on time information. The detection unit 225 detects tool damage by comparing the evaluation data and the corresponding baseline load data.

[0082] For example, in tapping, milling, and drilling operations where the tool breaks, the tool and workpiece do not contact each other during the cutting feed interval. Therefore, the value of the evaluation data is less than the value of the baseline load data. Figure 3 (3) and (4) Figure 4 (3) and (4), and Figure 5 (3) and (4)). Therefore, the detection unit 225 can detect the occurrence of tool damage by comparing the reference load data and the evaluation data.

[0083] The detection unit 225 detects the occurrence of tool damage based on at least one of the maximum, minimum, and average values ​​of the reference load data and at least one of the maximum, minimum, and average values ​​of the evaluation data. For example, the detection unit 225 compares the average value of the reference load data with the average value of the evaluation data to detect whether the tool has been damaged.

[0084] The detection unit 225 can also calculate at least one threshold based on at least one of the maximum, minimum, and average values ​​of the reference load data, and compare the calculated at least one threshold with at least one of the maximum, minimum, and average values ​​of the evaluation data to detect tool damage. For example, the detection unit 225 calculates a threshold equivalent to 50% of the average value of the reference load data. The detection unit 225 detects tool damage when the average value of the evaluation data is less than 50% of the average value of the reference load data.

[0085] When the detection unit 225 detects damage to the tool, the output unit 226 outputs data indicating that the damage has occurred. For example, the output unit 226 outputs the data indicating the damage to the tool to the display device 3. Upon receiving the data indicating the damage to the tool, the display device 3 displays on the screen that the damage to the tool has occurred.

[0086] If the detection unit 225 detects data indicating tool damage, the control unit 221 may, for example, issue an alarm indicating tool damage has occurred. Additionally, the control unit 221 may stop the operation of the machine tool 1 upon issuing an alarm.

[0087] Next, the process flow of the processing performed in the numerical control device 2 will be explained.

[0088] Figure 6 This is a flowchart illustrating an example of the processing flow performed in the numerical control device 2.

[0089] In the numerical control device 2, firstly, the data acquisition unit 222 acquires load data representing the spindle load in the cutting feed range and rotational speed data representing the spindle rotational speed (step SA1).

[0090] Next, the extraction unit 223 extracts evaluation data for assessing tool damage occurrence from the load data based on the rotational speed data. At this time, the extraction unit 223 extracts the load data as evaluation data for the section within the cutting feed range where the spindle rotates forward and the spindle rotational speed is fixed (step SA2).

[0091] Next, the inspection unit 225 uses the evaluation data to detect the occurrence of tool damage (step SA3). That is, the inspection unit 225 uses the evaluation data to determine whether tool damage has occurred.

[0092] If the detection unit 225 detects damage to the tool (if "yes" is detected in step SA3), the output unit 226 outputs data indicating that the tool damage has occurred (step SA4), and the process ends. For example, the output unit 226 outputs data indicating that the tool damage has occurred to the display device 3 of the numerical control device 2, and causes the display device 3 to display the data indicating that the tool damage has occurred.

[0093] If no damage to the tool is detected (if "No" is set in step SA3), return to step SA1 and continue acquiring load data and rotational speed data.

[0094] As described above, the tool damage detection device 2 includes: a data acquisition unit 222 that acquires load data representing the spindle load in the cutting feed range and rotational speed data representing the spindle rotational speed; an extraction unit 223 that extracts evaluation data used in evaluating the occurrence of tool damage from the load data based on the rotational speed data; a detection unit 225 that uses the evaluation data to detect the occurrence of tool damage; and an output unit 226 that outputs data representing the occurrence of tool damage when tool damage is detected by the detection unit 225. Therefore, by accurately capturing the characteristics of the load applied to the spindle, tool damage can be reliably detected.

[0095] Furthermore, the evaluation data consists of load data within the cutting feed range where the spindle rotates forward at a fixed speed. By setting the evaluation data to this value, tool damage during various machining processes, such as tapping, milling, and drilling, can be reliably detected.

[0096] Extraction unit 223 further extracts reference load data from the load data to serve as a benchmark for detecting tool damage. Detection unit 225 detects tool damage based on the reference load data and evaluation data. Furthermore, detection unit 225 detects tool damage based on at least one of the maximum, minimum, and average values ​​of the reference load data and at least one of the maximum, minimum, and average values ​​of the evaluation data. Therefore, compared to comparing all time-series data, the data processing load in detection unit 225 is reduced.

[0097] Furthermore, the detection unit 225 calculates at least one threshold based on at least one of the maximum, minimum, and average values ​​of the reference load data, and compares the calculated at least one threshold with at least one of the maximum, minimum, and average values ​​of the evaluation data to detect the occurrence of damage to the tool. Therefore, the threshold is automatically calculated without relying on the operator's experience, reducing the operator's burden.

[0098] In the above implementation, evaluation data is extracted based on rotational speed data. However, the implementation is not limited to this method; evaluation data can also be extracted based on the type of processing.

[0099] In this case, the data acquisition unit 222 acquires coordinate value data representing the coordinate values ​​of the cutting point, and the extraction unit 223 determines the type of machining performed by the tool based solely on the coordinate value data, or based on the rotational speed data and the coordinate value data, and extracts evaluation data according to the type of machining.

[0100] Coordinate data representing the cutting point's coordinates can be, for example, time-series data representing the coordinates of the tool's movement path in the workpiece coordinate system. The coordinates of the cutting point can be calculated, for example, based on values ​​detected by linear scales (not shown) positioned in various directions toward the X, Y, and Z axes.

[0101] The extraction unit 223 determines the type of machining by detecting the movement direction of the tool based on coordinate data. For example, if the tool moves in the X-axis or Y-axis direction but not in the Z-axis direction during the cutting feed interval, the extraction unit 223 determines that the machining is milling.

[0102] In addition, when the tool moves only in the Z-axis direction within the cutting feed range, the extraction unit 223 determines whether the machining is tapping or drilling.

[0103] Furthermore, if the tool moves only in the Z-axis direction within the cutting feed range, and if the cutting feed range includes a section where the tool's rotational speed is negative (i.e., a section where the tool reverses direction), the extraction unit 223 determines that the machining type is tapping. If the cutting feed range does not include a section where the tool reverses direction, the extraction unit 223 determines that the machining type is drilling.

[0104] Alternatively, the extraction unit 223 may determine that the type of machining is tapping if it determines that the rotation of the spindle includes both forward and reverse rotation, and that the amount of rotation when the spindle rotates forward is the same as the amount of rotation when it rotates in reverse.

[0105] When the extraction unit 223 determines that the type of machining is tapping, it extracts the load data of the section in the cutting feed range where the spindle rotates forward and the spindle rotation speed is fixed as the reference load data or evaluation data.

[0106] In addition, when the extraction unit 223 determines that the type of machining is milling or drilling, the entire range of the cutting feed interval is extracted as reference load data or evaluation data.

[0107] Next, the process flow executed in the numerical control device 2 is explained when the type of processing is determined and evaluation data is extracted based on the type of processing.

[0108] Figure 7 This is a flowchart illustrating an example of the processing flow performed in the numerical control device 2.

[0109] In the numerical control device 2, firstly, the data acquisition unit 222 acquires load data representing the load of the spindle in the cutting feed range, rotational speed data representing the rotational speed of the spindle, and coordinate data representing the coordinate values ​​of the cutting point (step SB1).

[0110] Next, the extraction unit 223 determines the type of processing (step SB2).

[0111] When the type of machining is tapping (if "Yes" is selected in step SB2), the extraction unit 223 extracts evaluation data for tapping (step SB3). That is, the extraction unit 223 extracts the load data as evaluation data for the section where the spindle rotates forward and the spindle speed is fixed within the cutting feed range.

[0112] If the machining type is not tapping (if "No" is selected in step SB2), the extraction unit 223 extracts evaluation data for milling or drilling (step SB4). That is, the extraction unit 223 extracts the entire range of the cutting feed interval as evaluation data.

[0113] Next, the inspection unit 225 uses the evaluation data to detect the occurrence of tool damage (step SB5). That is, the inspection unit 225 uses the evaluation data to determine whether tool damage has occurred.

[0114] If the detection unit 225 detects damage to the tool (if "yes" is detected in step SB5), the output unit 226 outputs data indicating the occurrence of tool damage (step SB6), and the process ends. For example, the output unit 226 outputs data indicating the occurrence of tool damage to the display device 3 of the numerical control device 2, and causes the display device 3 to display the data indicating the occurrence of tool damage.

[0115] If no damage to the tool is detected (if "No" is set in step SB5), return to step SB1 and continue to acquire load data, rotation speed data, and coordinate value data.

[0116] As explained above, the data acquisition unit 222 acquires coordinate data representing the coordinate values ​​of the cutting point, and the extraction unit 223 determines the type of machining performed by the tool based on the coordinate data, or the rotational speed data and the coordinate data, and extracts evaluation data based on the determined machining type. In this method of determining the machining type, it is not necessary to parse the instruction codes such as G-codes recorded in the machining program to determine the machining type. Therefore, it is easy to install a tool damage detection device on machine tools 1 that are already in use in the factory and do not have the function of determining the machining type based on instruction codes.

[0117] Furthermore, when the extraction unit 223 determines that the machining type is tapping, it extracts the load data of the section where the spindle rotates forward and its rotational speed is fixed within the cutting feed range as reference load data or evaluation data. Therefore, tool damage during various machining processes such as tapping, milling, and drilling can be reliably detected.

[0118] Furthermore, in cases where the likelihood of tool breakage is low, such as milling, identifying the type of machining allows for the exclusion of any tool damage from the inspection scope. In this case, it is unnecessary to store reference load data or evaluation data from the milling process in the storage unit 224, thus reducing the amount of data stored in the storage unit 224.

[0119] In addition, the data acquisition unit 222 can also acquire coordinate value data representing the coordinate values ​​of the cutting point, and the extraction unit 223 does not distinguish the type of machining, but extracts the evaluation data used in evaluating the occurrence of tool damage from the load data based solely on the coordinate value data, or based on the rotational speed data and the coordinate value data.

[0120] In this case, the extraction unit 223 detects the tool's movement direction based on coordinate data. For example, if the tool moves in the X-axis or Y-axis direction within the cutting feed interval, but does not move in the Z-axis direction, the extraction unit 223 extracts the entire cutting feed interval as evaluation data.

[0121] When the tool moves in the Z-axis direction within the cutting feed range, and the cutting feed range includes a range where the spindle rotation speed is negative, the extraction unit 223 extracts the load data of the range where the spindle rotates forward and the spindle rotation speed is fixed within the cutting feed range as reference load data or evaluation data.

[0122] When the tool moves in the Z-axis direction within the cutting feed interval and the cutting feed interval does not include any intervals where the spindle rotation speed is negative, the extraction unit 223 extracts the entire cutting feed interval as reference load data or evaluation data.

[0123] Therefore, the extraction unit 223 can extract evaluation data and baseline load data in the same way as when determining the type of processing.

[0124] Explanation of reference numerals in the attached figures

[0125] 1 machine tool

[0126] 2. Numerical control device (tool damage detection device)

[0127] 201CPU

[0128] 202 bus

[0129] 203ROM

[0130] 204 RAM

[0131] 205 non-volatile memory

[0132] 206 First Interface

[0133] 207 Second Interface

[0134] 208 Axis control circuit; 209 Spindle control circuit; 210 PLC

[0135] 211I / O Unit

[0136] 221 Control Department

[0137] 222 Data Acquisition Department 223 Extraction Department

[0138] 224 Storage Unit

[0139] 225 Testing Department

[0140] 226 Output Section

[0141] 3 Display devices

[0142] 4 input devices

[0143] 5 Servo Amplifier

[0144] 6 servo motors

[0145] 7-spindle amplifier

[0146] 71 Ammeter

[0147] 8. Spindle motor; 81. Speed ​​detector; 9. Auxiliary equipment.

Claims

1. A tool damage detection device, characterized in that, The tool damage detection device includes: The data acquisition unit acquires load data representing the load of the spindle in the cutting feed range, rotational speed data representing the rotational speed of the spindle, and coordinate data representing the coordinate values ​​of the cutting point. The extraction unit determines the type of processing performed by the tool based on the coordinate value data, or the rotation speed data and the coordinate value data, and extracts evaluation data used in evaluating the occurrence of tool damage from the load data based on the determined type of processing. The testing department uses the evaluation data to detect the occurrence of damage to the tool; and The output unit outputs data indicating the occurrence of damage to the tool when the detection unit detects damage to the tool.

2. The tool damage detection device according to claim 1, characterized in that, If the extraction unit determines that the type of processing is tapping, the load data of the interval in the cutting feed range where the spindle rotates forward and the spindle rotation speed is fixed is extracted as the evaluation data.

3. A tool damage detection device, characterized in that, The tool damage detection device includes: The data acquisition unit acquires load data representing the load of the spindle in the cutting feed range, rotational speed data representing the rotational speed of the spindle, and coordinate data representing the coordinate values ​​of the cutting point. The extraction unit extracts evaluation data used in assessing tool damage from the load data based on the coordinate value data and the rotation speed data. The testing department uses the evaluation data to detect the occurrence of damage to the tool; and The output unit outputs data indicating the occurrence of damage to the tool when the detection unit detects damage to the tool.

4. The tool damage detection device according to claim 1 or 3, characterized in that, The evaluation data is the load data within the cutting feed range where the spindle rotates forward and its rotational speed is fixed.

5. The tool damage detection device according to any one of claims 1 to 3, characterized in that, The extraction unit also extracts reference load data from the load data to serve as a benchmark for detecting damage to the tool. The detection unit detects damage to the tool based on the baseline load data and the evaluation data.

6. The tool damage detection device according to claim 5, characterized in that, The detection unit detects the occurrence of damage to the tool based on at least one of the maximum, minimum, and average values ​​of the reference load data and at least one of the maximum, minimum, and average values ​​of the evaluation data.

7. The tool damage detection device according to claim 6, characterized in that, The detection unit calculates at least one threshold based on at least one of the maximum, minimum, and average values ​​of the reference load data, and compares the calculated at least one threshold with at least one of the maximum, minimum, and average values ​​of the evaluation data to detect the occurrence of damage to the tool.

8. A computer-readable storage medium, characterized in that, The storage medium stores commands that cause the computer to perform the following steps: Obtain load data representing the spindle load in the cutting feed range, rotation speed data representing the spindle rotation speed, and coordinate data representing the coordinate values ​​of the cutting point; The type of processing performed by the tool is determined based on the coordinate value data, or the rotation speed data and the coordinate value data, and evaluation data used in evaluating the occurrence of tool damage is extracted from the load data based on the determined type of processing. The evaluation data is used to detect the occurrence of damage to the tool; and If damage to the tool is detected, data indicating the occurrence of the damage to the tool is output.

9. A computer-readable storage medium, characterized in that, The storage medium stores commands that cause the computer to perform the following steps: Obtain load data representing the spindle load in the cutting feed range, rotation speed data representing the spindle rotation speed, and coordinate data representing the coordinate values ​​of the cutting point; Based on the coordinate value data and the rotation speed data, extract the evaluation data used in evaluating the occurrence of tool damage from the load data; The evaluation data is used to detect the occurrence of damage to the tool; and If damage to the tool is detected, data indicating the occurrence of the damage to the tool is output.

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