JPH0620652B2 - Drilling load monitoring system for numerically controlled machine tools - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a load monitoring device for a tool when drilling a numerically controlled (hereinafter referred to as NC) machine tool.

(Technical background and problems to be solved) Conventionally, there are two types of monitoring devices for the machining load on the tool when performing drilling with an NC machine tool, one that does not detect machining load and the other that detects machining load. There is.

For a load monitoring device that does not detect machining load, after performing drilling at a certain depth, return the tool to the machining reference point to discharge chips, and prevent overload due to clogging of chips. Means and means for preventing overload due to deterioration of the cutting ability of the tool by replacing the current tool with the next tool after performing a certain number of drilling operations. However, both methods complicate the NC program, and since the boring process and the returning operation or the exchanging operation are always repeated at a constant cycle, even if the machining load is too small, the returning operation or the exchanging operation cannot be started. There are drawbacks such as loss of time and breakage of the tool by performing drilling despite the excessive processing load.

On the other hand, when a load over a certain value is detected, the load monitoring device that detects the machining load replaces the current tool with the next tool, or interrupts drilling, and Means are provided to prevent overload. However, with this method, even if the cause of the processing load of a certain value or more is not due to the deterioration of the cutting ability of the tool but due to clogging of chips, etc., replace the tool whose cutting ability has not deteriorated. Therefore, there have been various problems such as loss of time for the replacement operation and a large amount of tools, which increases the cost.

(Object of the Invention) The present invention has been made under the circumstances as described above, and an object of the present invention is to monitor a machining load applied to a tool of an NC machine tool and always perform drilling with an appropriate machining load. (EN) Provided is a drilling load monitoring device for an NC machine tool capable of performing the following.

(Means for Solving Problems) The present invention relates to a load monitoring device for a tool when performing drilling with an NC machine tool, and the above object of the present invention is to provide a detection means for detecting the processing load. A detection unit provided, a setting unit in which an overload determination value for the processing load detection value is preset, a comparison unit for comparing the processing load detection value and the overload determination value, and the processing load by this comparison. When the detected value exceeds the overload determination value, a determination unit that determines the state of the tool, a storage unit that stores the pre-processing state of the drilling in advance, the tool state and the previous state based on the determination. A generation unit that generates a machining control signal from a combination of machining states, an interruption unit that interrupts the numerical control command during the drilling according to the machining control signal to interrupt, and the position of the tool at the time of this interruption. A storage unit for storing, After performing predetermined treatment returns the serial tool to a predetermined position, it is achieved by providing the restart unit for restarting the numerical control command that returned this tool to the interruption position.

(Operation of the Invention) The drilling load monitoring device in the NC machine tool of the present invention is
Machining control signals are generated from the tool status and the pre-machining status to control machining, so it is possible to constantly monitor so that an appropriate machining load condition is reached, and at the time of machining control, a numerical control command during drilling When the process is interrupted, the numerical control command is restarted from the interrupted position, so that quick drilling can be performed.

(Embodiment of the Invention) FIG. 1 is a block diagram showing an example of a drilling load monitoring device in an NC machine tool according to the present invention, and a sensor 101 for detecting a machining load applied to a tool when performing drilling. When,
A processing load detection unit 102 that averages and smoothes the detection signal SA from the sensor 101 to obtain a processing load signal value (hereinafter referred to as a load value) SB, and determines that the tool is overloaded. A judgment value setting unit 104 in which a power overload judgment value (hereinafter referred to as a judgment value) SC is stored in advance, and a load value SB from the processing load detection unit 102 is a judgment value SC from the judgment value setting unit 104.
When the load value SB exceeds the judgment value SC, the processing control signal generation request signal SD is input to the processing control signal generation unit 105, and the timer control request signal SE is input to the timer control unit 106. And 103. Then, the comparison unit 103
In response to the timer control request signal SE from, the timer comparison request signal SF is input to the timer comparison unit 109, and the timer comparison unit 109
The timer controller 106 that receives the timer clear request signal SG from the timer clear signal SH and inputs the timer clear signal SH to the timer 107 to clear the timer value SI, and the reason why the load value SB exceeds the judgment value SC is that the chips are clogged, etc. To determine whether it is due to a transient or due to tool chipping, wear, etc., start at the same time as machining starts, and set the timer value SI until the load value SB exceeds the judgment value SC as the threshold value SJ. Timer comparison section 109 for comparison
And a threshold value SJ for judging whether or not the cause of the overload is due to a transient, and the timer 107 which starts upon receiving the timer start signal SY from the NC restart unit 114.
Is stored in advance and the timer comparison request signal SF from the timer control unit 106 is received, the timer value SI from the timer 107 is compared with the threshold value SJ from the timer setting unit 108, and the timer value When the SI exceeds the threshold value SJ, the tool normal signal SK is input to the machining control signal generation unit 105, and
Input the timer clear request signal SG to the timer control unit 106,
When the timer value SI does not exceed the threshold value SJ, the tool abnormality signal SL is input to the machining control signal generation unit 105, and the timer comparison request signal SG is input to the timer control unit 106. Have In addition, the above-mentioned timer value refers to a time elapsed from the start of machining or the time when the load value exceeds the determination value last time until the load value exceeds the determination value this time. Further, in response to the pre-machining state storage unit 110 in which the pre-machining state SP is stored in advance and the machining control signal generation request signal SD from the comparing unit 103, the timer comparing unit 109
Inputs the machining control signal SQ to the NC interrupt unit 111 based on the combination of the tool normal signal SK / tool abnormal signal SL from the pre-machining state storage unit 110 and the pre-machining state SP from the pre-machining state storage unit 110, and the pre-machining state change signal. When the machining control signal generator 105 for inputting SR to the pre-machining state storage unit 110 and the machining control signal SQ from the machining control signal generator 105 are received, the NC program execution stop signal SS or the feed axis, spindle stop signal ST is NC. It is input to the program execution unit 112 and the NC restart request signal SU is input to the NC restart unit 114, and the NC interrupt execution signal SS from the NC interrupt unit 111 The current position SV is stored in the current position storage unit 113, and the NC program execution unit 112 that restarts the NC program in response to the NC restart signal SW from the NC restart unit 114 and the current position storage unit 113 Return the tool to the position SX, and receive the NC restart request signal SU from the NC interrupt unit 111 to restart the NC. An NC restart unit 114 for inputting a start signal SW to the NC program execution unit 112 and a start signal SY for the timer 107 is provided.

In such a configuration, the operation will be described with reference to the flowchart of FIG. 2. The timer starts counting, and then it is confirmed whether or not the drilling process is completed (step S1).
When the drilling process is completed, all the processes are completed.
On the other hand, in the previous term determination step S1, if the drilling is not completed, the load value SB input by the comparison unit 103 via the sensor 101 and the processing load detection unit 102 is the determination value setting unit 1
Check if the judgment value SC from 04 is exceeded (step S
2) If the load value SB does not exceed the judgment value SC, check again. On the other hand, in the judgment step S2, the load value
When SB exceeds the judgment value SC (Fig. 3 (A)), the comparison unit 1
03 processing control signal request signal SD processing control signal generation unit 105
And a timer control request signal SE to the timer control unit 106. Then, when the timer control unit 106 inputs the timer comparison request signal SF to the timer comparison unit 109, the timer comparison unit 109 determines that the timer value SI from the timer 107 is the timer setting unit.
Check whether the threshold value SJ from 108 has been exceeded (step S3). If the timer value SI exceeds the threshold value SJ, it means that the normal cutting state has continued for a certain time or longer. When the previous load value SB exceeds the determination value, it is determined that the tool has no problem. Therefore, the cause of the overload is considered to be transient, and the timer comparison unit 10
9 inputs the tool normal signal SK to the machining control signal generation unit 105. On the other hand, in the judgment step S3, when the timer value SI does not exceed the threshold value SJ, it means that the normal cutting state has not continued for a certain period of time, so the previous load value SB exceeds the judgment value SC. It is determined that there was a problem with the tool. Therefore, it is considered that the cause of the overload is not transient, so the timer comparison unit 109 causes the tool abnormality signal S
Input L to the processing control signal generation unit 105. Then, the machining control signal generation unit 105 receives the machining control signal generation request signal SD from the comparison unit 103, receives the tool normal signal SK / tool abnormal signal SL from the timer comparison unit 109, and the previous machining state storage unit 110 NC suitable machining control signal SQ by combination of machining status SP
Input to the interrupt unit 111. FIG. 4 shows the machining control signal SQ for the combination of the tool normal signal SK / tool abnormal signal SL and the pre-machining state SP, and the normal cutting SPA is a state where there is no overload after the start of machining. The re-approach SPB is the state in which the tool was once returned to the machining reference point when the last overload occurred, and then NC machining is continued.The tool replacement SPC is the last overload occurrence. Sometimes it means that the current tool is replaced with the next tool. Therefore, when the tool normal signal SK is input to the processing control signal generation unit 105 (Yes in step S3), or when the tool abnormality signal SL is input to the processing control signal generation unit 105, the pre-processing state SP is If it is a normal cutting SPA (step S4),
A machining control signal SQ that allows the machining control signal generation unit 105 to continue machining by NC after the tool once returns to the machining reference point.
Is input to the NC interrupt unit 111, the NC interrupt unit 111 inputs the NC program execution stop signal SS to the NC program execution unit 112. At the same time, the machining control signal generation unit 105 outputs a signal SR for changing the pre-machining state SP to the re-approach SPB.
Input to 10 (step S6). And NC program 11
2 stores the current position SV at the time of stopping the NC program execution in the current position recording unit 113 (step S7), temporarily returns the tool T to the machining reference point a (Fig. 3 (B)), and eliminates chip clogging. Yes (step S8). On the other hand, the timer control unit 106 receives the timer clear request signal SG from the timer comparison unit 109, inputs the timer clear signal SH to the timer 107, and clears the timer value SI (step S9). Then, the NC restart unit 114
Upon receiving the NC restart request signal SU from the interrupt unit 111, the tool T is returned to the current position SX when the NC program execution is stopped, which is stored in the current position storage unit 113 (Fig. 3 (C), step S1.
0), NC program restart signal SW to NC program execution unit 1
12 is input to restart machining (step S11), the timer start signal SY is input to the timer 107 to start the timer 107 (step S12), and the process returns to step S1.

On the other hand, in the determination step S4, when the tool abnormality signal SL is applied to the machining control signal generation unit 105, the pre-machining state SP
Is not the normal cutting SPA, it is confirmed whether or not the pre-machining state SP is the re-approaching SPB (step S5), and if the pre-machining state SP is not the re-approaching SPB, step S20.
Proceed to. On the other hand, in the determination step S5, if the previous machining state SP is the re-approach SPB, the machining control signal generation unit 105 once returns the tool to the machining reference point, and then replaces the current tool with the next tool. When the machining control signal SQ for continuing machining by NC is input to the NC interrupt unit 111, the NC interrupt unit 111 inputs the NC program execution stop signal SS to the NC program execution unit 112. At the same time, the machining control signal generation unit 105 inputs the signal SR for changing the pre-machining state SP to the tool exchange SPC to the pre-machining state storage unit 110 (step S13). And NC
The program execution unit 112 stores the current position SV at the time when the NC program execution is stopped in the current position storage unit 113 (step S1
4) The tool T is once returned to the machining reference point a and the current tool is replaced with the next tool (step S15). After that, the same operations as those in steps S9 to S12 described above are performed (steps S16 to S19), and the process returns to step S1.

On the other hand, in the determination step S5, when the pre-processing state SP is not the re-approach SPB, the processing control signal generation unit 105
Control signal that causes the feed axis and spindle to temporarily stop
When SQ is input to the NC interrupt unit 111, the NC interrupt unit 111 inputs the feed axis and spindle stop signal ST to the NC program execution unit 112, and N
The C program execution unit 112 temporarily stops the feed axis (step S20) and stops the spindle (step S21). on the other hand,
The timer control unit 106 receives the timer clear request signal SG from the timer comparison unit 109, inputs the timer clear signal SH to the timer 107, and clears the timer value SI (step S22). Then, in this case, the restart of the NC is entrusted to the operator or the like, and when the operator or the like restarts, the machining control signal generation unit 105 outputs the signal SR for changing the pre-machining state SP to the normal cutting SPA. Input to the storage unit 110, return to step S1, and repeat the above-described operation.

(Effects of the Invention) As described above, according to the drilling load monitoring device in the NC machine tool of the present invention, since the monitoring is continuously performed so that an appropriate machining load state is always maintained, it is necessary to perform the returning operation and the exchanging operation of the tool. The productivity can be improved with the minimum number of times, and the cost can be reduced by automation and unmanned operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a hole drilling load monitoring device in an NC machine tool of the present invention, FIG. 2 is a flow chart for explaining the operation, and FIGS. 3 (A) to 3 (C) are machining states, respectively. And FIG. 4 is a diagram showing a machining control signal. 101 ... Sensor, 102 ... Processing load detection unit, 103 ... Comparison unit, 104 ... Judgment value setting unit, 105 ... Processing control signal generation unit, 106 ... Timer control unit, 107 ... Timer, 108 ... … Timer setting section, 109 …… Timer comparing section, 110 …… Previous machining state storage section, 111 …… NC interruption section, 112 …… NC program execution section, 113 …… Current position storage section, 114 …… NC re-setting section Start-up section.

Claims (1)

[Claims] 1. A detection unit provided with a detection unit for detecting a processing load applied to a tool when performing drilling with a numerically controlled machine tool, and a detection unit after the processing is started or restarted after the processing is interrupted. A timer unit that counts elapsed time, a tool abnormality determination value setting unit that presets a tool abnormality determination value for this elapsed time, and an overload determination that presets an overload determination value for this machining load detection value A value setting unit, a comparing unit that compares the processing load detection value and the overload determination value, and when the processing load detection value exceeds the overload determination value by this comparison, the elapsed time is the tool abnormality determination. If it exceeds the value, the state of the tool is determined to be normal, and if the elapsed time does not exceed the tool abnormality determination value, a determination unit that determines the state of the tool to be abnormal, and the drilling process Pre-processing state remembered When the tool state is normal, a machining control signal for returning the tool to a predetermined position is generated from the combination of the pre-machining state storage section and the tool state and the machining state determined by the determination, and the tool is When the state is abnormal, if the pre-machining state is normal cutting, a machining control signal for only returning the tool to a predetermined position is generated,
If the pre-machining state is a re-approach, a machining control signal for returning the tool to a predetermined position and for tool exchange is generated, and if the pre-machining state is tool exchange, a machining control signal for interrupting machining is generated. Section, an interrupting section for interrupting the numerical control command during the drilling according to this machining control signal to interrupt, a position storage section for storing the position of the tool at the time of this interruption, and the tool for a predetermined position. And a restarting unit for returning the tool to the interruption position and restarting the numerical control command after performing a predetermined treatment. .