JP2770053B2 - Cutting tool damage detection device with learning function - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tool damage detection device that automatically detects when a tool is damaged during cutting.

"Conventional technology and problems" The variable load current value or power value from the start of the spindle motor until it reaches the steady speed is much larger than the fluctuating current value caused by damage to the cutting tool, so the spindle motor approaches the steady speed. Therefore, it is necessary to detect the damage of the cutting tool after the fluctuation of the load current value is reduced.

For this reason, conventionally, the time from the start of the spindle motor until it reaches the steady speed is experimentally grasped, and the cutting feed is started at the time when the time that allows for the experimental value has passed, and at the same time, the comparison with the set value is performed. To detect damage to the cutting tool.

However, this method has the following problems in the case of a machine that processes a workpiece whose processing changes in a complicated manner, such as a machining center.

In other words, by changing blades one after another, a large difference occurs in the time required for the spindle motor to reach a steady rotation speed due to a difference in the weight of the blades or a difference in the number of cutting revolutions. Began to occur.

As a countermeasure, there is a method of changing to a control circuit equipped with a number of timers so that the time to start comparing the load current value and the set value can be set for each replacement blade, or a state where multiple blades to be used are mounted on the spindle Select the cutting tool that spent the longest time until the spindle reaches the steady-state rotation speed, and after this steady-speed reaching time, all the blades to be replaced start cutting feed and set value and load current value The method of starting the detection of the damage of the cutting tool by the comparison object has been taken.

These methods have problems such as complicating the control circuit and wasting cutting time.

In addition, as a method of determining a set value, conventionally, data on load current was collected by a recorder or the like in actual processing, and based on this, an abnormal load current value due to the degree of damage to each cutting tool was estimated and determined as a set value. .

"Means for Solving the Problem" The present invention has been made in view of the above-mentioned problems, and has been made in view of the above problems. And start of tool damage detection.

As a result, a plurality of cutting tools can be quickly cut without impairing the cutting tool damage detection accuracy, and all the cutting tools can perform cutting processing without wasted time.

Also, if an arbitrary number of measurements and a margin rate are set in advance as a setting method of the set value, the mounted cutting tool actually processes the specified work on the same machine an arbitrary number of times, and the processing is completed and monitored until that time. A value obtained by multiplying the average value of the machining load current value by the set margin ratio can be automatically set as a set value in the storage unit.

This makes it possible to automatically set the set value while actually processing the work under the same conditions as the actual processing.

The above-described function of automatically setting the set value is hereinafter referred to as a learning function in the present invention.

(Action) The cutting feed command by the learning function is set immediately after the elapse of that time, assuming the longest time required for the spindle speed to reach the steady speed in the specifications of the processing machine. After the set time has elapsed, monitoring of the cutting feed and the machining load current value is performed. Thus, during this time, the machining load current value for each cutting tool is monitored,
A set value obtained by multiplying the average machining load current value of the number of times of learning by a preset margin rate of each cutting tool is automatically set in the system.

When the set value is automatically set, the learning function is turned off and automatically switches to the normal blade damage detection function. When the set value is set, the load current value of the spindle-mounted cutting tool, which changes from the start of the spindle motor to the steady rotation speed, falls below the set value. If a load current exceeding a set value is generated within the blade damage detection period up to the above, an abnormal signal is output.

By setting the set values of all the tools to be changed in this way, each blade starts cutting from the minimum idle operation, and automatically detects the damage of the tools corresponding to the set values of each tool. Done

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a graph showing a model of a change with time of a current or an electric power value from a rising start of a spindle motor having a specific cutting tool attached to a spindle to a machining state in a machining machine. “a” is a range showing a change in current from the time when the spindle motor is attached to a specific cutting tool to the time when cutting is performed.

“b” indicates a current value in a so-called idling state in which the specific cutting tool does not receive a cutting load due to the cutting rotation.

In this drawing, the idle operation range is shown as a large time range. However, in the present invention, the cut-off feed signal is output at the same time as the load current value falls below the set value W so that the idle operation time can be shortened as much as possible. ing.

c is a range indicating a machining state in which a cutting load is applied to a specific cutting tool.

W indicates a set value, and is a value determined by multiplying the load current value in the machining state by a margin ratio. The set value can be set for the number of replacement blades so that blade damage detection can be performed for each blade.

P indicates an abnormal waveform due to the breakage of the blade, indicating a load current value exceeding the set current value immediately before the blade is broken, and then a sharply falling due to the breakage of the blade, and eventually indicating a load current value close to idle operation. This is a time-specific waveform. As described above, when the cutting load current value exceeds the set value W due to the breakage of the cutting tool or the wear damage of the cutting tool, an abnormal signal is output to return the machine to the original position, or to return to the cutting tool replacement operation position. It is.

Next, the learning function will be described. The learning function monitors the machining load current value of the work actually being machined,
This function refers to the function of automatically inputting the maximum current value as a set value by multiplying it by a preset margin ratio into the device storage unit. The monitoring of the output of the cutting feed enable signal and the load current value is started from the time when the time has elapsed.

In this case, the setting of the time until reaching the steady rotation speed can be easily set because it is sufficient to determine the time with a margin.

When the learning function is instructed to perform learning an arbitrary number of times, the above operation is repeated an arbitrary number of times, and when the number of times of instruction is completed, the maximum load current value monitored for each number of times is calculated as an average value of the number of times of learning instruction. At the same time, a value multiplied by a preset margin rate is automatically input as a set value to the device storage unit to turn off the learning function and switch to normal blade tool damage detection.

As a result, the set value is set based on the average load current during normal machining, so that the set value can be optimized, and the detection accuracy due to wear damage of the cutting tool can be improved.

FIG. 2 is a flowchart showing an embodiment of the present invention. First, in step 100, data is initialized, and in step 102, the spindle motor starts rotating. And step 104
If the learning function is checked in step 1 and the learning function is to be performed, step 1 is performed after the time set in step 106 has elapsed.
The tool damage detection and cutting feed signal are output through 10,112.

If it is determined in step 104 that the learning function is not to be performed, the stability of the spindle motor is determined, and when the current value falls below the set value, the process proceeds to step 110 for blade tool damage detection.

In step 116, the set value is compared with the load current value. If the machining is completed with the load current value equal to or less than the set value, the process proceeds to step 118 as normal.

In step 118, the processing amount is determined and the processing returns to step 114 until the processing amount is completed, and the tool damage is detected with the same set value. When the machining of the predetermined machining quantity is completed, in step 120, if the maximum load current value within the set value is larger than the previously measured and stored maximum load current value, a new maximum load current value is set. The data is newly rewritten and stored in the storage unit, and the blade tool damage detection is completed.

If a load current exceeding the set value is indicated in step 116, it is determined that the load current is abnormal, an abnormal signal is output, and the measured value at this time is stored in the storage unit, thereby completing the blade tool damage detection.

In the case of the learning function, the learning function ON is determined in step 126, and the measured value measured in step 116 is stored in step 130.

In step 132, the process returns to step 126 until the designated number of times is completed by counting the number of learning times instructed any number of times, and the measured value is stored.
Move to 4.

In step 134, an average value is calculated from the measured values stored in step 130, and a set value is calculated by multiplying the average by the margin ratio.

In step 136, the blade damage detecting device stores the data in step 100, automatically stops the learning function in step 138, and returns to the start position.

(Effect) As described above, the effect of the present invention can be set automatically by setting the set value by the learning function, so that the set value closer to the current state can be set automatically. Detection accuracy can be improved.

In addition, when machining a workpiece that changes in a complicated manner, such as machining in a machining center, with multiple cutting tools, the conventional tool damage detection is performed because the cutting operation can be shifted from the idle operation state to the minimum cutting preparation for each cutting tool to cutting processing. The processing efficiency can be improved as compared with the apparatus.

[Brief description of the drawings]

FIG. 1 is a graph showing a model of a change in a current value or a power value with respect to time from a start-up start of a spindle motor to a machining state in a machining machine. FIG. 2 is a flowchart showing an embodiment of the present invention. a: rising fluctuation time, b: idle operation time, c: normal processing time, P: breakage abnormal waveform, W: set value.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23Q 17/09

Claims (1)

(57) [Claims] A detecting unit for detecting a load current or electric power of a spindle motor; a storing unit for storing a set value for determining damage to a cutting tool; a comparing unit for comparing the detected load current with the set value; And a means for outputting an abnormal signal when the applied load current exceeds a set value, wherein the setting value setting means instructs an arbitrary number of learning times and a margin rate for each cutting tool mounted on the spindle as the setting value setting means. In this way, the workpiece is actually machined, and the machining load current value or power value detected at that time is calculated as the average value of the number of times of learning. A cutting tool damage detection device, comprising a function of automatically switching to a cutting tool damage detection function after setting a larger value as a new set value in a storage unit.