JPS6133644B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting abnormal conditions such as wear and breakage of the tip of an electric drill.

When drilling a hole in a workpiece using an automatic electric drill, if you continue the work without noticing that the tip of the drill is worn or broken,
This results in a large number of defective products and hinders productivity. SUMMARY OF THE INVENTION An object of the present invention is to provide a device for monitoring wear, breakage, etc. of the tip of a drill in order to prevent such accidents.

The present invention takes advantage of the fact that when the tip of an electric drill is worn, the input load power increases, and when it breaks, it decreases, and the input power value when the electric drill is in a no-load state is stored in advance in the storage device. The input power value when the electric drill is under load is compared with the power value stored in the storage device, and when the difference output exceeds a predetermined range, the discrimination circuit This system detects abnormal conditions and displays abnormal conditions or issues an alarm.

Embodiments of the present invention will be described below with reference to the drawings. The figure is a block diagram showing one embodiment of the present invention.
1 is a power supply circuit, and electric drill 2 is connected to this power supply circuit 1.
It is connected to the. 3 indicates the tip of the drill 2, and 4 indicates the workpiece. 5 is a current detection device such as a current transformer that detects the input current of the electric drill 2, 6 is a voltage detection device such as a voltage transformer, and the current value and voltage value detected by 5 and 6 are transferred to a multiplier circuit 7. An output signal corresponding to the multiplicative product is calculated. Reference numeral 8 denotes a memory circuit that stores the output of the multiplier circuit 7 corresponding to the multiplicative product of the current value and the voltage value when the electric drill 2 is not in contact with the workpiece 4, that is, when it is rotating under no load. A storage operation is performed in response to a signal from a storage instruction device 10 by closing a switch 9 which operates when a load is applied. Reference numeral 11 compares the data stored in the memory circuit 8 with the output signal of the multiplier circuit 7 when the drill point 3 of the electric drill 2 hits the workpiece and the electric drill is under load, and outputs the difference. A comparator circuit 12 is a circuit that determines whether the comparison output of the comparator circuit 11 is within a predetermined value range, exceeds an upper limit value, or exceeds a lower limit value. A device that is activated by the closing of a switch 13 that is closed at the timing when the tip of the drill hits the workpiece and starts work, and immediately issues a discrimination command for a predetermined period of time for the time required for normal drilling work. It is configured to display and transmit the determination results to the alarm device 15 in accordance with instructions from the alarm device 14. 16 is a monitor that displays the comparison results of the comparison circuit 11;

If you now close the switch of the electric drill 2 and rotate it, the switch 9 will close when there is no load, and the signal from the memory instruction device 10 will correspond to the product of the current value and voltage value when the electric drill 2 is under no load. The signal is stored in storage device 8. Tip 3 of drill 2
When the machine hits the workpiece 4 and starts drilling, the switch 9 is opened and the storage operation in the storage device 8 is stopped. At the same time, the switch 13 is closed and a signal is output from the discrimination command generation device 14, and the discrimination device 12 is activated. The comparator circuit 11 compares the output of the multiplier circuit 7 corresponding to the product of the current value and the voltage value of the electric drill 2 under load and the output of the multiplier circuit 7 under no load read from the storage device 8. They are compared, and a comparison output, which is the difference between the two, is displayed on the monitor 16 and at the same time is applied to the discrimination circuit 12, which discriminates the state of the tip based on the comparison output. That is, the discrimination circuit 12 is the comparison circuit 11.
It is determined whether the output is within a predetermined value range, exceeds the upper limit value, or exceeds the lower limit value, and transmits the result to the display device or alarm device 15.

If the tip 3 of the drill is worn out, the load on the electric drill increases, and if the tip breaks, the load decreases, and as a result, the comparison is the difference output from the value stored in the storage device 8 when no load is applied. The output of the circuit 11 exceeds the upper limit or lower limit of the discriminating circuit 12 and displays the abnormality on the display device 15.

When the electric drill 2 finishes the drilling work and enters the no-load state, the device 14 that generates the discrimination command displays an abnormality on the display device 15 because the predetermined time has elapsed and the discrimination command has not been generated. There isn't.

As described above, the present invention detects an abnormality in the tip of the drill by determining the load condition of the drill using the electrical input of the electric drill. However, in the present invention, the comparator 11 detects input fluctuations caused by factors other than the load applied to the tip of the drill, such as the condition of the oil film on the bearing and temperature changes. By subtracting the electrical input when the drill is rotating under no load from the electrical input when the drill is in the normal state, only the load fluctuations caused by the drill drilling operation are extracted. This is compared with a predetermined voltage set in advance by the discrimination circuit 12 to detect abnormalities in the tip of the drill bit, so even slight fluctuations in the input power can be easily detected, and it is possible to detect differences in the material of the workpiece. Accurate discrimination can always be made even when the thickness of the tip or the shape of the tip is different. In addition, since the input power in the no-load state is subtracted from the input power in the loaded state and added to the discrimination circuit 12, in the case where the tip of the drill bit is broken, the input power is not added to the discrimination circuit. The input signal is almost close to 0, so a lower limit value is set in addition to the upper limit value in the discriminating circuit 12, and a case where the input signal does not reach the lower limit value can be determined to detect a broken tip. Furthermore, the operation of subtracting the electrical input in the no-load state from the electrical input in the loaded state is performed by reading out the signal stored in the storage device 8 during the no-load state in the comparator circuit 11 during the load state. The time lag between the operation and the comparison operation is small, so that the comparison operation is accurate. Effects such as this can be obtained.

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of the present invention. 2...Electric drill, 7...Multiplication circuit, 8...Memory circuit, 11...Comparison circuit, 12...Discrimination circuit,
15...Display, alarm circuit.

Claims (1)

[Claims] 1. A circuit that detects the input voltage and input current of the electric drill and generates a signal corresponding to the synergistic value thereof, a memory circuit that stores the signal when the electric drill is rotating under no load, and the electric drill. a comparison circuit that compares a signal corresponding to the synergistic value with a signal stored in the storage circuit when the device is in a loaded state and extracts a difference output; It is equipped with a discrimination circuit that discriminates whether the value exceeds a lower limit value, and an alarm device that notifies the discrimination result of the discrimination circuit. A signal corresponding to the synergistic value of the input voltage and input current of the electric drill is stored in the storage circuit, and a signal corresponding to the synergistic value of the input voltage and input current of the electric drill at that time is stored in the storage circuit, and the signal corresponding to the synergistic value of the input voltage and input current of the electric drill at that time is stored in the storage circuit. The electric drill is characterized in that the comparison circuit compares the signal stored in the memory circuit, and the difference output is added to the discrimination circuit to notify wear and breakage of the tip of the drill. Anomaly detection device.