JPH032621B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a tool breakage detection device that can automatically detect breakage of a drill or the like.

[Technical background of the invention and its problems]

2. Description of the Related Art As electronic devices become lighter and smaller, the circuit boards used therein are becoming more dense. In this high-density circuit board, the circuit elements to be mounted are naturally becoming smaller, and various holes formed in the printed circuit board, such as mounting holes for mounting them, are also necessarily smaller in diameter. In other words, what used to be 0.8mm in diameter,
They are 0.3mm and 0.1mm.

Normally, this printed circuit board drilling is performed by an automatic drilling machine using a drill, and if a breakage of the drill is detected, the drilling process is immediately stopped. Conventionally, there are two types of detectors for detecting breakage of a drill: (a) one that detects changes in cutting torque due to breakage, and (b) an AE sensor installed at the spindle head where the drill is attached, and output from this AE sensor. There are various types of methods, such as (c) those that irradiate the drill with a light beam emitted from the projecting head through an optical fiber and optically detect the breakage of the drill from the amount of light that enters the receiving head. There is.

However, these conventional detectors have a limit of detecting a breakage of a drill with a diameter of 0.8 mm, and cannot reliably detect a breakage of a drill smaller than that.

In other words, what is detected from the change in cutting torque and the signal output from the AE sensor is that as the diameter of the drill decreases, the cutting torque and
The AE signal itself becomes smaller, the S/N ratio decreases, and it becomes undetectable. In addition, for optical detection, the light emitted from the tip of the optical fiber is diffused at an angle of about 60 degrees, so if the diameter of the drill becomes small, the light emitted from the tip will be received regardless of whether there is a drill or not. It enters the head, making it impossible to detect drill breakage.

[Purpose of the invention]

The present invention was made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a tool breakage detection device that can automatically and accurately detect the quality of drilling by a small-diameter drill.

[Summary of the invention]

After drilling, the broken state is determined based on the amount of infrared rays output from the tip of the drilling tool.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

1 and 2 show the tool breakage detection device of this embodiment. This device is arranged by a support (not shown) in close proximity to a hole 3 of a workpiece 2 by a drill 1, and generates a detection signal SD indicating the temperature of the tip of the drill 1 based on infrared rays R emitted from the drill 1. Infrared detection unit 4 to convert and detection signal SD
Electrical signal ST indicating the temperature of the tip of drill 1 based on
a temperature conversion unit 5 for determining the breakage state of the drill 1 based on the detection signal ST; a breakage determination unit 6 for determining the breakage state of the drill 1 based on the detection signal ST; It is composed of a temperature display section 7 such as the following. The infrared detection section 4 and temperature conversion section 5 constitute an infrared radiation temperature detector D. However,
The infrared detector 4 includes a lens system 8 that focuses the infrared rays R emitted from the drill 1, and is provided on the light output side of this lens system 8 to receive the focused infrared rays R and convert them into an electric signal SA corresponding to the amount of received light. an infrared sensor 9 for converting, a photodetector 10 that is inserted between the lens system 8 and the infrared sensor 9 and focuses the infrared ray R on the infrared sensor 9 in a timely manner by opening and closing operations;
Connected to the output side of the infrared sensor 9 and outputs an electric signal SA
It consists of an amplifier 11 that amplifies the electric signal SB, and a filter circuit 12 that passes only the required frequency component indicating the temperature of the drill 1 out of the electric signal SB output from the amplifier 11. Moreover, the temperature converter 5 is
It consists of a linearizer 13 that inputs the detection signal SD output from the filter circuit 12 and converts it into an electrical signal ST indicating the temperature, and a correction circuit 14 that corrects the conversion formula of this linearizer. On the other hand, the breakage determination unit 6 inputs the electrical signal ST output from the linearizer 13, compares it with a preset setting value _T1 , and outputs an abnormality signal SI when the electrical signal ST is lower than the set value _T1 . A first comparator circuit 15 is provided in parallel to the first comparator circuit 15, which inputs an electric signal ST and outputs an abnormality signal SJ when the electric signal ST is higher than a preset setting value _T2 . a second comparison circuit 16 that outputs;
It consists of an OR circuit 17 connected to the output sides of these first and second comparison circuits 15 and 16.
Then, the output side of the OR circuit 17 is an NC ( Numerial
ontrol (numerical control) unit 19, and is connected to the abnormal signal
SK is output to the NC section 19.
The output side of the OR circuit 17 is also connected to the display section 7 to display the determination result. Further, the NC section 19 is also connected to the infrared detection section 4 and the display section 7, and is adapted to output a breakage control signal SL in a timely manner based on the machining program.

Next, the operation of the tool breakage detection device configured as described above will be described.

As shown in FIG. 1, when the drilling of the workpiece 2 by the drill 1 is completed, the photo-chopper 10 is operated based on the control signal SL from the NC unit 19, and the infrared rays R emitted from the tip of the drill 1 are reflected by the lens system 8. It is focused on the mission sensor 9. Next, the infrared sensor 9 outputs an electrical signal SA having a voltage corresponding to the amount of infrared rays R received via the amplifier 11 to the filter circuit 12 as an electrical signal SB. Next, the electric signal SB is filtered by the filter circuit 12, and a detection signal SD having only the required frequency components is outputted to the linearizer 13.
In this linearizer 13, the detection signal SD is converted into an electric signal ST indicating the temperature of the drill 1. Next, this electric signal is output to the display section 7 and displayed as the temperature T of the tip of the drill 1, and is also output to the first and second comparison circuits 15 and 16.
is output to. By the way, if the drill 1 is broken as shown in FIG. 3, the workpiece 2 will not be drilled. Therefore, the temperature of the drill 1 does not rise. Therefore, as shown in Figure 4A, the set value
The temperature T indicated by the electric signal ST is lower than _T1 . As a result, the abnormal signal SI is output from the first comparison circuit 15 to the OR circuit 17, and this OR circuit 1
From 7, an abnormal signal SK is output to the NC unit 19. Then, the NC section 19 outputs a control signal to the drilling machine 18 to interrupt the drilling operation in order to replace the drill. On the other hand, as shown in FIG. 5, when the drill 1 is worn out due to long-term use, it is heated to a higher temperature immediately after drilling is completed than when it is not worn out. Therefore, as shown in FIG. 4B, the temperature T' indicated by the electric signal ST becomes higher than the set value _T2 . As a result, the abnormal signal SJ from the second comparison circuit 16 is OR
It is output to the circuit 17, and from this OR circuit 17,
An abnormality signal SK is output to the NC section 19, and the drilling operation is interrupted in the same manner as before. However, since drill 1 is in a normal state, drill 1 immediately after drilling
The temperature at the tip is T ₁ <T″< as shown in Figure 4C.
It has become T ₂ . As a result, the abnormal signal SK is not output from the OR circuit 17 to the NC section 19, and the drilling operation continues according to the machining program.

As described above, the tool breakage detection device in this embodiment detects abnormalities based on the amount of infrared rays emitted from the tip of the drill, so the breakage detection accuracy is improved.

Note that the second comparison circuit 16 in the above embodiment
may be omitted, and only complete breakage may be detected. Furthermore, the output side of the linearizer 13 may be connected to a microcomputer via an analog-digital A/D, and the breakage determination may be performed by software processing. Furthermore, the present invention is not limited to drills, but can also be applied to detecting breakage of reamers, taps, etc.

〔Effect of the invention〕

The tool breakage detection device of the present invention detects tool breakage based on the amount of infrared rays emitted from the tip of the drilling tool, improving detection accuracy and contributing to automation of drilling work. Especially, 0.8mm
When applied to breakage detection of the following small diameter drills, it is particularly effective.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a tool breakage detection device according to an embodiment of the present invention, FIG. 2 is a block diagram showing the electric circuit system of FIG. 1, FIG. 3 is a diagram showing a drill in a broken state, and FIG. The figure is a graph for explaining breakage determination, and FIG. 5 is a diagram showing a drill in a worn state. 1: Drill (drilling tool), 2: Workpiece,
4: Infrared detection section, 5: Temperature conversion section, 6: Breakage determination section.

Claims (1)

[Claims] 1. An infrared detection unit that receives infrared rays emitted from a drilling tool after drilling a workpiece and converts it into an electrical signal, and an infrared detection unit that detects the temperature of the drilling tool based on the electrical signal output from this infrared detection unit. A temperature conversion unit that converts the temperature into a reference value is set in advance, and an electric signal indicating the temperature of the drilling tool outputted from the temperature conversion unit is compared with the set value, and based on the comparison result, the temperature conversion unit converts the A tool breakage detection device comprising: a breakage determination section that determines whether or not a drilling tool is broken.