JP2520017B2 - Machining load monitoring method and device for drilling - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a machining load monitoring method and a device therefor in drilling by a numerical control (NC) machine tool.

(Prior Art) In the conventional machining load monitoring method for drilling, the sensor (vibration detection sensor or cutting force detection sensor) used for the monitoring is selected according to the operator's judgment, or similar to milling or end milling. The tool diameter is used as a parameter, and if the diameter is small, a sensitive vibration detection sensor (for example,
AE (Acoustic Emission) sensor, etc.) and a stable cutting force detection sensor (for example, load current sensor of spindle motor etc.) for large diameter are automatically set.

FIG. 5 is a block diagram showing an example of a conventional machining load monitoring device, which is an AE wave SA during machining detected by the AE sensor 101.
Are subjected to processing such as filtering for amplification and noise removal in the AE signal processing unit 102 and averaging at fixed time intervals, and are sent to the used sensor switching unit 105 as the AE signal SB. Also,
The load current value SC of the spindle motor detected by the spindle load current sensor 103 is subjected to processing such as averaging at fixed time intervals in the spindle load current signal processing unit 104, and is used as the spindle load current signal SD in the used sensor switching unit 105. Sent out.

In the use sensor setting unit 110, a command SE indicating which of the AE sensor 101 and the spindle load current sensor 103 is used for machining load monitoring is set in advance by a parameter or a machining program, and this use sensor command SE is used. When sent to the sensor switching unit 105, the AE signal SB and the used sensor are
E The signal SF notifying that it is the sensor 101, or the spindle load current signal SD and the sensor used are the spindle load current sensor 103
The signal SG indicating that is sent to the comparison unit 106.

The threshold setting unit 109 is preset with an AE signal threshold SH and a spindle load current signal threshold SI, and the AE signal SB or the spindle load current sent to the comparing unit 106 is set. The signal SD is compared with the threshold value SH for the AE signal or the threshold value SI for the spindle load current signal read from the threshold value setting unit 109,
The request signal SJ of the processing control signal SK is the processing control signal generation unit 107
Sent to And processing control signals such as tool wear signals
The SK is generated by the processing control signal generation unit 107 and sent to the NC device 108.

In such a configuration, an example of the operation will be described with reference to the flowchart of FIG. 6, it is determined whether or not the processing is finished (step S1), and when the processing is finished, all the processing is finished. If the processing is not completed, whether the usage sensor switching unit 105 is a command to use the AE sensor 101 or a usage sensor command SE from the usage sensor setting unit 110 is a command to use the spindle load current sensor 103. Is determined (step S2). When the use sensor command SE is a command to use the spindle load current sensor 103, the use sensor switching unit 105 compares the spindle load current signal SD with the signal SG indicating that the use sensor is the spindle load current sensor 103. Part 1
It is sent to 06 (step S3). The comparison unit 106 compares the spindle load current signal SD sent out with the threshold SI for the spindle load current signal read from the threshold setting unit 109 (step S4), and the spindle load current signal SD is compared with the spindle load current signal SD. If it is smaller than the load current signal threshold value SI, the process returns to step S1 and repeats the above operation. If the spindle load current signal SD is equal to or higher than the spindle load current signal threshold value SI, the processing control signal SK is requested. The signal SJ is sent to the machining control signal generator 107, and the process proceeds to step S7.

On the other hand, in the judgment step S2, the use sensor command is issued.
When SE is a command to use the AE sensor 101, the used sensor switching unit 105 determines that the AE signal SB and the used sensor are the AE sensor 1
The signal SF notifying 01 is sent to the comparison unit 106 (step S5). The comparison unit 106 outputs the transmitted AE signal S
B and threshold value SH for AE signal read from threshold value setting section 109
Are compared with each other (step S6), and if the AE signal SB is smaller than the AE signal threshold SH, the operation returns to step S1 and the above operation is repeated, and the AE signal SB is equal to or larger than the AE signal threshold SH. In the case of, the request signal SJ of the processing control signal SK is sent to the processing control signal generator 107, and the process proceeds to step S7.

The processing control signal generation unit 107 generates the processing control signal SK and sends it to the NG device 108 (steps S7 and S8), and returns to step S1 to repeat the above-described operation.

(Problems to be Solved by the Invention) The selection criterion of the processing load monitoring sensor in the above-described conventional processing load monitoring device is the tool diameter. However, for example, when cutting aluminum with a tool peripheral speed of 40 m / min using HSS steel drills with different diameters, the feed rate of the drill and the AE signal (average value when the AE sensor was mounted on the work side and measured for a certain period of time) ), The result of the experiment is shown in Fig. 7 (●;
φ3.3mm, ○; φ5.0mm, ×; φ15mm).
That is, even if the tool diameter is changed, the AE signal does not show a correlation with the increase in the feed rate (increase in the processing load), so it is meaningless to select the sensor for monitoring the processing load depending on the tool diameter. found.

The present invention has been made under the circumstances as described above, and an object of the present invention is to automatically select a sensor for monitoring a machining load according to a cutting condition for drilling at that time. It is intended to provide a processing load monitoring method and an apparatus thereof.

(Means for Solving the Problem) The present invention provides a method for drilling with an NC machine tool,
The vibration during the drilling is detected and the cutting force is detected, and the machining control signal is generated only when the vibration detection value or the cutting force detection value selected according to the predetermined condition exceeds the predetermined threshold value. The present invention relates to the machining load monitoring method and the apparatus therefor, the object of the present invention is to input the cutting conditions for the drilling, determine the tool peripheral speed from the input cutting conditions, and calculate the tool peripheral speed. It is achieved by selecting the vibration detection value when it is a certain value or more, and by selecting the cutting force detection value when the tool peripheral speed is less than the certain value, and drilling with an NC machine tool. Means for detecting vibration at the time, means for detecting the cutting force at the time of drilling, means for inputting the cutting conditions for the drilling, and means for calculating the tool peripheral speed from the input cutting conditions, Tool peripheral speed is above a certain value Select the vibration detection value when,
A means for selecting the cutting force detection value when the tool peripheral speed is less than the predetermined value, and a machining control signal only when the selected vibration detection value or the cutting detection value exceeds a predetermined threshold value. And means for generating.

(Operation) The machining load monitoring method and device for drilling of the present invention uses the tool peripheral speed, which is one of the cutting conditions, as the selection criterion for the sensor for monitoring the machining load, and is suitable for the cutting conditions. The processing load can be accurately monitored by the processing load monitoring sensor.

(Example) The principle of the selection standard of the sensor for monitoring the processing load of the method for monitoring the processing load during drilling of the present invention is shown in FIGS. 3 (A), (B) and 4 (A), (B). It will be explained based on the experimental results of.

Figures 3 (A) and (B) show a tool peripheral speed of 20 m / min and feed per revolution of 0.1 mm / rev using a HSS steel drill with a diameter of 3 mm.
In the structural carbon steel (S45C), a hole with a depth of 10 mm is continuously drilled, and a spindle load current signal (average value during drilling one hole) at the time of drilling 10 holes before and after the constant number of holes. ) And the average value of the AE signal (the average value when one AE sensor is attached to the work side and one hole is drilled).
In addition, FIGS. 4 (A) and (B) plot the average value of the spindle load current signal and the average value of the AE signal when cutting under the same conditions as in FIG. 3 except that the tool peripheral speed was 30 m / min. It is a thing.

As is clear from the figure, at a tool peripheral speed of 2 m / min, the spindle load current signal has a positive correlation with the increase in the number of holes (the increase in machining load due to tool wear), but there is no AE signal. It shows no correlation. In addition, the tool peripheral speed is 30 m / min
In Fig. 2, the AE signal shows a positive correlation with a large change with respect to the increase in the number of machined holes (increased machining load due to tool wear) compared to the spindle load current signal. From the above results, it has been found that the tool peripheral speed, which is one of the cutting conditions for drilling, may be used as the selection criterion for the sensor for monitoring the machining load of the method for monitoring the machining load during drilling of the present invention.

FIG. 1 is a block diagram showing an example of a machining load monitoring device in the drilling process of the present invention, corresponding to FIG. 5, and the same components are designated by the same reference numerals and the description thereof will be omitted. This machining load monitoring device uses the tool diameter D and the spindle speed S in the cutting conditions for drilling instead of the conventional sensor setting unit 110.
Is sent from the NC device 108 to the cutting condition input unit 201, the tool peripheral speed f _w is calculated and sent to the sensor switching signal generation unit 202, and the tool peripheral speed f _w and the sensor switching signal generation unit 202 are previously set. The use sensor command SE is sent to the use sensor switching unit 105 according to the comparison result with the set constant tool peripheral speed F _w .

In such a configuration, an example of the operation will be described with reference to the flowchart of FIG. 2, it is determined whether or not the processing is finished (step S11), and when the processing is finished, all the processing is finished. When the machining is not completed, the cutting condition input unit 201 inputs the tool diameter D and the spindle rotational speed S from the NC device 108 in the drilling machining cutting conditions (step S12),
The tool peripheral speed f _w is calculated by the following equation (1) (step S1
3), and sends it to the sensor switching signal generator 202.

f _w = π · D · S (1) The sensor switching signal generation unit 202 sends the tool peripheral speed f
Compare the magnitude of _w with a preset constant tool peripheral speed F _w (step S14), and if the tool peripheral speed f _w is less than or equal to the set tool peripheral speed F _w , use the spindle load current sensor 103. The command is sent to the used sensor switching unit 105. Used sensor switching unit 1
05 sends the spindle load current signal SD and the signal SG indicating that the sensor used is the spindle load current sensor 103 to the comparison unit 106 (step S15). The comparison unit 106 compares the magnitude of the spindle load current signal SD sent out with the threshold SI for the spindle load current signal read from the threshold setting unit 109 (step
S16), if the spindle load current signal SD is smaller than the spindle load current signal threshold SI, the operation returns to step S1 and the above operation is repeated until the spindle load current signal SD is equal to or greater than the spindle load current signal threshold SI. In the case of, the processing control signal SK request signal
SJ is sent to the processing control signal generation unit 107 and the process proceeds to step S19.

On the other hand, in the determination step S14, when the tool peripheral speed f _w is higher than the set tool peripheral speed F _w , the sensor switching signal generation unit 202 sends a command to use the AE sensor 101 to the used sensor switching unit 105. The used sensor switching unit 105 outputs an AE signal SB and a signal SF notifying that the used sensor is the AE sensor 101.
And are sent to the comparison unit 106 (step S17). Comparison unit 106
Compares the magnitude of the sent AE signal SB with the AE signal threshold SH read from the threshold setting unit 109 (step
S18), if the AE signal SB is smaller than the threshold value SH for the AE signal, the process returns to step S1 to repeat the above operation,
If SB is above the threshold SH for AE signals, processing control signal SK
The request signal SJ is sent to the processing control signal generator 107, and the process proceeds to step S19.

The processing control signal generation unit 107 generates the processing control signal SK and sends it to the NC device 108 (steps S19, S20), and step S1.
Then, the above operation is repeated.

In the embodiment described above, the vibration detection sensor
Although the case where the spindle load current sensor is used as the AE sensor and the cutting force detection sensor has been described, a vibration acceleration sensor may be used instead of the AE sensor, or instead of the spindle load current sensor, or A feed axis load current sensor in the thrust direction of a drilling tool or a cutting dynamometer may be used together with the spindle load current sensor. And
When f _w > F _w , 1 out of the detection values of multiple vibration detection sensors
A machining control signal may be generated when one detected value exceeds the threshold value, or when all detected values exceed the threshold value. If f _w ≤ F _w , multiple cutting forces may be generated. The processing control signal may be generated when one of the detection values of the detection sensor exceeds the threshold value, or when all the detection values exceed the threshold value.

Further, in the above-described embodiment, the tool diameter D is set to the NC device 10.
I am trying to send from 8 to the cutting condition input section 201,
An operator or the like may manually input the cutting condition input unit 201.

(Effect of the Invention) As described above, according to the machining load monitoring method and the apparatus therefor of the present invention, it is possible to select the most suitable machining load monitoring sensor according to the cutting conditions of the drilling process. By strictly monitoring the processing load, it is possible to prevent malfunctions. Then, it is possible to improve product quality and productivity.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a machining load monitoring device in drilling of the present invention, FIG. 2 is a flow chart for explaining an operation example thereof, FIGS. 3 (A), (B) and FIG. 4 (A). ) And (B) are diagrams showing the relationship between the number of processed holes and sensor signals for explaining the principle of the selection criterion of the sensor for monitoring the processing load in the method for monitoring the processing load during drilling of the present invention, respectively. FIG. 6 is a block diagram showing an example of a conventional machining load monitoring device for drilling, FIG. 6 is a flowchart explaining an example of its operation, and FIG. 7 is a diagram showing the relationship between the tool feed speed and sensor signals. is there. 101 ... AE sensor, 102 ... AE signal processing unit, 103 ... Spindle load current sensor, 104 ... Spindle load current signal processing unit, 105
…… Sensor switching unit, 106 …… Comparison unit, 107 …… Machining control signal generation unit, 108 …… NC device, 109 …… Threshold setting unit, 201 …… Cutting condition input unit, 202 …… Sensor switching Signal generator.

Claims (2)

(57) [Claims] 1. When performing drilling with a numerically controlled machine tool, the vibration detection value or the cutting force detection value selected under predetermined conditions is detected by detecting the vibration during the drilling and the cutting force. In the machining load monitoring method in which the machining control signal is generated only when exceeds a predetermined threshold value, the cutting conditions for the drilling are input, and the tool peripheral speed is calculated from the input cutting conditions. When the tool peripheral speed is a certain value or more, the vibration detection value is selected, and when the tool peripheral speed is less than the certain value, the cutting force detection value is selected. Method of monitoring processing load in processing. 2. A means for detecting a vibration during drilling by a numerically controlled machine tool, a means for detecting a cutting force during the drilling, a cutting condition for the drilling, and the input cutting. Means for calculating the tool peripheral speed from the condition, and when the calculated tool peripheral speed is a certain value or more, select the vibration detection value,
A means for selecting the cutting force detection value when the tool peripheral speed is less than the predetermined value, and a machining control signal only when the selected vibration detection value or the cutting force detection value exceeds a predetermined threshold value. And a processing load monitoring device in drilling.