JPH0349849A - Tool damage detecting device with study function - Google Patents

Abstract

PURPOSE:To prepare cutting work to be promptly started without deteriorating accuracy of detecting damage for a plurality of tools by starting a feed of cutting and detection of tool damage from the point of time in which a fluctuating load current, generated by starting a spindle motor, is decreased to not more than a current value preset in each tool. CONSTITUTION:A data is initialized in a step 100, when a spindle motor is started to rotate in a step 102, a signal of tool damage detection and cutting feed is output through steps 110, 112. A preset value is compared with a load current value in a step 116, when work is finished by a load current value not more than the preset value, a procedure is advanced to a step 118 by deciding the normal and returned to a step 114 to perform tool damage detection by the same preset value before a work quantity is completed by judging the predetermined work quantity. When a maximum load current value in the preset value in a step 120 is larger than the maximum load current value measured and stored in the preceding time, the new maximum load current value is newly rewritten and stored in a memory part, and the tool damage detection is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a cutting tool damage detection device that automatically detects damage to a cutting tool during cutting.

"Conventional technology and problems" The fluctuating load current or power value from startup until the spindle motor reaches a steady rotation speed is much larger than the fluctuating current value caused by damage to the cutting tool, so the spindle motor approaches a steady rotation speed. It is necessary to detect damage to the cutting tool after the fluctuation of the load current value decreases.

For this reason, in the past, the time required for the spindle motor to reach a steady rotation speed after startup was determined experimentally, and after the time had elapsed with a margin added to this experimental value, cutting feed was started and at the same time a comparison target with the set value was set. The method used was to go there and detect damage to the cutting tool.

However, this method has caused the following problems in the case of machines such as machining centers that process workpieces whose processing changes in a complex manner.

In other words, when cutting tools are replaced one after another, the time it takes for the spindle motor to reach a steady rotational speed becomes large due to differences in the weight of the cutting tools and differences in cutting speed, which causes problems in the accuracy of damage detection for many cutting tools. began to occur.

As a countermeasure to this problem, there is a method of changing the control circuit to a control circuit equipped with multiple timers so that the time to start comparing the load current value and set value can be set for each replacement cutting tool, and a method of installing multiple cutting tools to be used on the main shaft. Select the cutting tool that took the longest time for the spindle to reach the steady rotational speed, and after this time to reach the steady rotational speed, all the cutting tools scheduled for replacement will start cutting feed, and the set value and load current value will be changed. A method has been adopted in which tool damage detection is started using a comparison target.

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

In addition, the conventional method of determining the set value is to collect data regarding the load flow using a recorder, etc. during actual machining, and based on this data, estimate the abnormal load current value depending on the degree of damage to each cutting tool and determine the set value. Ta.

"Means for Solving the Problem" The present invention was made in view of the above problems, and the cutting feed starts when the fluctuating load current generated by starting the spindle motor becomes less than the set current value set for each cutting tool. and started tool damage detection.

As a result, cutting can be started quickly without compromising the precision of damage detection for multiple cutting tools, and all cutting tools can be cut without wasting time.

In addition, if you set the desired number of measurements and margin rate in advance as a way to set the set value, the installed cutting tool will actually process the specified workpiece any number of times on the same machine, and as soon as the process is completed, it will be monitored. The value obtained by multiplying the average value of the machining load current value by the set margin rate can be automatically set in the storage unit as the set value.

This makes it possible to automatically set the setting values while actually machining the workpiece under the same conditions as actual machining.

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

(Function) Cutting processing using the learning function allows a certain amount of margin in the time it takes for the spindle motor to reach a steady rotation speed from startup with a specific cutting tool attached to the spindle under conditions within the possible range of the processing machine. Set the estimated time.

After this set time has elapsed, monitoring of the cutting feed and machining load current value is performed. In this way, the machining load current value during this period is monitored, and a set value is automatically set in the system by multiplying the average machining load current value of the number of learning times by an appropriately set margin rate.

Once the set value is automatically set, the learning function will be turned off and the function will automatically switch to the normal cutting tool damage detection function. By setting the set value, the load current value, which changes from the start of the spindle motor to the steady rotation speed, drops below the set value, and at the same time, the cutting feed starts and the tool damage detection function works, preventing tool damage until machining is completed. If a load current exceeding a set value is generated within the detection period, an abnormality signal is output.

By setting the setting values for all the cutting tools to be replaced in this way, each cutting tool starts cutting with minimal idle operation, and damage to the cutting tool is automatically detected with high accuracy according to the setting values of each cutting tool. It is carried out according to

(Example) An embodiment of the present invention will be described below based on the accompanying drawings.

FIG. 1 shows a graph modeling the change in current or power value over time from the start-up of a spindle motor in which a specific cutting tool of a processing machine is attached to the spindle until the machining state. a is a range showing the change in current until the spindle motor starts cutting rotation when a specific cutting tool is attached.

b indicates the current value when the particular cutting tool is in a so-called idling state where no cutting load is applied during cutting rotation.

In this figure, the idle running range is shown as a large time range, but in the present invention, the cutting feed signal is output as soon as the load current value falls below the set value W, so that the idle running time can be made as short 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, which is the load in the machining state [a value determined by multiplying the flow value by the margin rate. This set value can be set as many times as the number of replacement blades, so that damage to each blade can be detected for each blade.

P indicates an abnormal waveform due to a breakage of the cutter; immediately before the cutter breaks, the cutter shows a load current value that exceeds the set flow value, and then suddenly drops due to the breakage of the cutter, and then shows a load current value close to dry operation. This is a waveform for damage detection. In this way, when the cutting load current value exceeds the set value W due to breakage of the cutter or wear and tear on the cutter, a signal is output to return the machine to its original position or to the position where the cutter is replaced. It is a device.

Next, the learning function will be explained. The learning function is a function that monitors the current value of the machining load of the workpiece that is actually being processed, multiplies this maximum current value by a preset margin rate, and automatically inputs the result as a set value into the device memory. When the function is started, the output of the cutting feed enable signal and the monitoring of the load current value are started after a preset time has elapsed, that is, the time from when the spindle motor is started until it reaches a steady rotation speed.

In this case, the time required to reach the steady rotation speed can be easily set because it can be determined with a little margin.

In addition, by instructing the learning function to perform learning an arbitrary number of times, the above operation is repeated an arbitrary number of times, and when the instructed number of times is completed, the maximum load current value monitored each time is calculated as the average value of the number of learning instruction times. At the same time, a value multiplied by a preset margin rate is automatically input into the device storage section as a set value, the learning function is turned off, and the cutting tool damage detection is switched to normal.

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 accuracy of detection due to wear and tear on the cutting tool can be improved.

FIG. 2 is a flow chart showing one embodiment of the present invention. First, data is initialized in step 100, and the main shaft motor starts rotating in step 102. Then, in step 104, it is confirmed whether or not to perform the learning function.
When performing this function, after the time set in step 106 has elapsed, steps 110 and 112 are performed to detect damage to the cutting tool and output a cutting feed signal.

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 a set value, the process moves to step 110 to detect damage to the cutting tool.

In step 116, the set value and the load current value are compared, and if machining is completed with a load less than the set value at the current value, it is determined to be normal and the process moves to step 118.

In step 118, a predetermined machining quantity is determined, and until the machining quantity is completed, the process returns to step 114 and the cutter damage detection is performed using the same set value. When machining of a predetermined 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 information is newly rewritten and stored in the storage unit, and the tool damage detection is completed.

If the load current exceeds the set value in step 116, it is determined that there is an abnormality and an abnormality signal is output, and the measured value at this time is stored in the storage section, and the cutting tool damage detection is completed.

In the case of the learning function, it is determined in step 126 whether the learning function is ON, and the measured value measured in step 116 is sent to step 13.
Store as 0.

Step 132 counts the specified number of learning times, returns to step 126 and stores the measured values until the designated number of times is completed, and moves to step 134 when the designated number of learning times is completed.

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 value by the margin rate.

In step 136, the cutting tool damage detection device stores the data in step 100, automatically stops the learning function in step 138, and returns to the starting position.

(Effect) As explained above, the effect of the present invention is that by automatically setting the setting value using the learning function, it is possible to automatically set the setting value that is closer to the current situation. Detection accuracy can be improved.

In addition, when machining a workpiece that changes complexly, such as when machining with a machining center, using multiple cutting tools, conventional tool damage detection can be used because it is possible to move from an idle state for minimal machining preparation for each tool to cutting processing. Processing efficiency can be improved compared to other machines.

[Brief explanation of drawings]

FIG. 1 shows a graph modeling the change in current value or power value over time from the startup of the spindle motor in a processing machine to the processing state. FIG. 2 is a flow chart showing one embodiment of the present invention. a...Rise fluctuation time, b...idling time, C...normal machining time, P...breakage abnormal waveform, W...setting value.

Claims (1)

[Claims] (1) A detection unit that detects the load current or power of the spindle motor, a storage unit that stores the set value for determining damage to the cutting tool, a comparison unit that compares the detected load current with the set value, and the detected load current is set. In a cutting tool damage detection device equipped with a means for outputting an abnormal signal when a value exceeds a value, the load current or power exceeds a preset value from the start of the spindle motor until it reaches a steady rotation speed. is excluded from the comparison with the set value, and the cutting feed command is output from the moment the load current value shows less than the set value, and the load current value is compared with the set value, and the load current value exceeds the set value. A cutter damage detection device characterized by outputting a cutter abnormality signal at certain times. (2) A detection unit that detects the load current or power of the spindle motor, a storage unit that stores the set value for determining damage to the cutting tool, a comparison unit that compares the detected load current with the set value, and the detected load current is set. In a cutting tool damage detection device comprising a means for outputting an abnormal signal when a value exceeds the set value, the means for setting the set value is to actually machine the workpiece an arbitrary number of times and set the average value of the machining load current value or power value. A cutter damage detection device characterized by having a function of automatically setting a value obtained by multiplying by a margin rate in a storage unit as a set value.