JPS62124809A - Detecting device for breakage of drill - Google Patents

Abstract

PURPOSE:To prevent a device, which detects a breakage of a drill, from misoperation due to a dust, by providing a means which receives reflection of light irradiated to a point end of the drill and detects the reflection of the light for whether the drill is broken or not and for whether the dust exists or not. CONSTITUTION:An optical fiber group 3, forming a paired bundle of light projecting and receiving optical fibers, is set separating from so as to diagonally cross with in the point end of a drill 2 mounted to a chuck 1. A signal from the light receiving optical fiber is amplified by an amplifying unit 4, and its output is divided into two branches. One is a system 5 for detecting a break of the drill and the other is a system 6 for measuring whether an influence by a dust exists or not. In the system 5, a detection logical operation circuit 7 decides the drill 2 to perform normal action, when light is reflected, while the drill to be broken when no light is reflected. In the system 6, the output is processed by a band pass filter 9, and its output is decided by a circuit 10, then a circuit 8, detecting existence of the dust, removes it by stopping drilling.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a drill breakage detection device.

[Technical background and problems of the invention]

Miniaturization is progressing. In the past, a drill with a length of 1 mm or more was used, but recently, drilling with a drill of 1 nm to 0.3111 m is now in practical use. This drilling process is executed automatically based on NC data, and what is important is that any abnormality caused by damage or breakage of the drill, such as breakage, is immediately detected and managed to prevent it from proceeding to the first process. It is to be. Due to this need, many proposals have been made for methods of detecting breakage of tools such as drills. The present inventor has already filed an application that a breakage detection method using light projected by an optical fiber and reflected light from the drill is excellent for detecting breakage of a small diameter drill of 1n or less.

That is, this is a method of detecting the breakage of a drill based on the presence or absence of reflected light from the drill. using this method.

It has been found that the following malfunctions may occur as a result of automatic drilling using a drill.

In other words, if debris such as chips adheres to the tip of the optical fiber, for example, if the light emitting fiber or the receiving 7-eyeper is obscured by debris, the light will not be emitted to the drill, or the light receiving fiber will detect the reflected light from the drill. In any case, as a result, the receiving fiber output is lost, so even if it is normal, it may be mistaken as a broken drill, and the drilling operation may be stopped. Furthermore, if the light from the transmitting fiber is reflected by dust and this reflected light enters the receiving fiber, the drill will break and the receiving fiber will break even though there is no reflected light from the drill to detect the breakage. Light enters the drill, causing it to malfunction when it is operating normally, and drilling holes with a broken drill to proceed with the work, which has the drawback of producing a large number of defective products when drilling holes such as printed circuit boards.

[Purpose of the invention] This invention has been made to address the above points.

The present invention provides a drill breakage detection device that prevents malfunction of drill breakage detection due to dust.

[Summary of the invention]

The tip of the drill is irradiated with light from a first optical fiber, and the reflected light from the drill is received by a second optical fiber to detect breakage. The converted signal is supplied to a bandpass filter of a predetermined frequency.

A drill breakage detection device is provided which is provided with a means for detecting whether the output signal of this filter is a drill breakage or light reflected by dust.

In other words, based on the fact that the photoelectric conversion output of the second optical fiber for light reception due to the influence of dust is a direct current component with no level fluctuation, it is possible to distinguish it from the reflected light from the drill using the output signal of the bandpass filter. The purpose is to determine.

[Embodiments of the invention]

Next, an embodiment of the device of the present invention will be described with reference to the drawings.

At the tip of a drill (2) attached to a chuck (1), an optical fiber group (3) consisting of a pair of light-emitting optical fibers and light-receiving optical fibers is set so as to be diagonally intersecting.

The light projecting optical fiber of this optical fiber group (3) projects output light from a light source, such as an LED, through this optical fiber. On the other hand, the light incident on the light-receiving optical fiber is converted into an electrical signal by a photoelectric conversion element (not shown), and this signal is amplified by an amplifier unit (4).
) Branch the output into two. On the other hand.

One is a drill breakage detection system (5), and the other is a part for measuring the presence or absence of dust influence (6). The former drill breakage detection system (5) is a detection logic circuit (7) that detects the presence or absence of reflected light from the drill using the light-receiving optical fiber of the optical fiber group (3). (2) is determined to be normal operation, and in the case of 2 reflected light and heat, it is determined and output as an abnormal state in which the tip of the drill (2) is broken and separated or lost. If it is determined that there is an abnormality, an abnormality signal is output from the abnormality detection signal output circuit (8), and actions such as displaying 1 and stopping the drilling operation of the drill (2) are performed.

The latter dust influence measurement system (6) converts the output of the incident light from the received light optical fiber into a band pass filter (9), which converts the output from the optical fiber into a signal specific to the influence of dust and a signal of the reflected light from the drill. ) The output of this filter (9) is processed so as to be able to be judged, and the output of this filter (9) is judged by a detection logic bean, and when a signal due to the influence of dust is detected, an abnormality signal is output from the abnormality detection signal output circuit (8). The 1 display and the drilling operation of the drill (2) are stopped, and the dust is removed. For example, if the drill (2) rotates at a rotation speed n and has two blades, the waveform of the reflected light from the drill (2) shown in Fig. 2 (A), which fluctuates minutely at a period of 2n, is a bandpass. Input to filter (9). This filter (9) is a filter that filters a signal having a frequency corresponding to a period of 2n, and the waveform shown in FIG. 2(B) in which the DC component is cut passes. When this passed signal is below a preset threshold value, it is output from the detection logic circuit (7) as an abnormality.

In addition, the light from the above-mentioned light emitting optical fiber is reflected by dust,
When this reflected light is received by the light-receiving optical fiber, an electric signal obtained by photoelectrically converting the output of the light-receiving optical fiber outputs a constant voltage as shown in FIG.

This phenomenon occurs because the reflected light does not change over time because the dust is stationary and specific. Since this output level is above the threshold, the abnormality detection output circuit (8) does not operate.

The low frequency components are filtered out by the bandpass filter (9) and the signal shown in FIG. 2(D) is supplied to the detection logic circuit α. In this circuit Ql, a zero signal with low frequency components cut is below the threshold value.

An abnormal operation is output, and an abnormality detection signal output circuit (8) outputs an abnormal signal.

In addition, if dust adheres to at least one of the optical fibers for transmitting and receiving optical fibers, that is, if dust adheres to the exit window of the optical fiber for transmitting light and no light is emitted, the light enters the optical fiber for receiving light. There's no light. Furthermore, even if dust adheres to the entrance window of the light-receiving optical fiber, there will be no incident light on the light-receiving optical fiber and the output will be below the threshold, so the detection logic circuit α1 will determine that it is an abnormal operation. Output anomaly detection. In this way, malfunctions such as broken drills due to debris can be detected.

Next, a more specific example of the former drill breakage detection system will be described.

That is, this embodiment has the following characteristics so that even a small-diameter drill can detect breakage.

■The optical fiber receives light from the bright light, but the reflected light from the drill is particularly suitable for detecting breakage of a small diameter drill of 1 m or less.

∎The setting position of the optical fiber must be in the area shown in Figure 3.

■The detection operation should be performed every time the drilling operation is completed and the drill tip separates from the object to be drilled.

■Monitor minute breakages that occur at the tip of the drill.

etc.

Regarding the above, optical detection methods include, as is well known, a transmission method as well as a reflection method.

This transmission type detection method is a method in which a light receiving part is set in the transmitted optical path through a drill, but if the diameter of the drill is smaller than the diameter of the light beam from the light source side, it becomes impossible to block the optical path with the drill during normal operation. It becomes difficult to distinguish between a normal state and a broken state. As a result of concentrating the optical fiber irradiation light to 1 nm or less using a condenser lens, as shown in Figure 4 (A), the allowable amount of drill deviation in the X direction compared to the Y direction is approximately 100.
If the drill position deviates even slightly from the fiber axis, detection becomes impossible. (Here, the above-mentioned X direction is a direction perpendicular to the optical axis, and the above-mentioned Y direction is the optical axis direction.) On the other hand, if the reflected light from the drill is received by an optical fiber, the side surface of the drill Since this method causes diffuse reflection and detects a portion of this reflected light with a light receiving fiber, there is no need to narrow down the single beam with a lens, and detection is possible even if the beam is not necessarily perpendicular to the drill. Quantitatively, the drill detectable area is as shown in FIG. 4(B), and compared to FIG. 4(A), the drill detectable area is wider and more practical.

Good detection results can be obtained.

Regarding (■) above, we investigated the detectable area by the receiving optical fiber in an optical system in which the irradiated light from the original fiber is projected onto the tip of the drill and the reflected light from the drill is received by the receiving optical fiber. is shown in Figure 3. That is, the horizontal axis is the axial position of the light-receiving optical fiber, and the MI axis is the position of the light-receiving surface of the light-receiving optical fiber in the direction perpendicular to the axial direction of the optical fiber.

In Fig. 3, when the tip of the drill is located on the plane consisting of the fiber axis and the axis perpendicular to this, the detection area where the light-receiving optical fiber receives the reflected light from the drill is a curved line. This is the area surrounded by 6υ. That is, if the drill exists within the area surrounded by one curve 51), the light receiving fiber detects the reflected light. The dashed line indicates the axis of the optical fiber. Furthermore, when the drill breaks and the tip of the drill retreats upward from the axis of the optical fiber, the detectable area by the light-receiving optical fiber is the area surrounded by the curve 2.

Therefore, the drill measurement (breakage detection) position is curve ci1)
It was found that breakage could not be detected unless the light-receiving optical fiber detection area was set within the range surrounded by , excluding the range surrounded by the first curved line.

Regarding ■■, instead of measuring the middle part of the bird, the tip of the drill is used as the measuring position in order to detect damage as well. This is because drilling is often completed only at the tip, causing damage.

This is based on the fact that an initial phenomenon occurs at the tip.

To measure the tip of the drill in this way.

After drilling is completed, the drill tip is exposed, away from the body of the person to be drilled, in order to move to the work position for the first drilling, and then irradiate and measure.

Next, a description will be given with reference to FIGS. 5 to 7.

A workpiece, such as a printed circuit board, is placed on a base, such as an X-Y table (not shown). This X-Y table is controlled in accordance with pre-programmed NC data and the like to control the movement of the hole drilling by Drill Co., Ltd. in accordance with the process order and processing acclimation.

1 on the printed circuit board (1) whose movement is controlled in this way.
A drill of size u or smaller, for example, a 0.3111 drill (this is an example of a configuration consisting of two drills. This drill (company) is chucked on a rotating main shaft (c), and this main shaft is attached to a slider plekuya foot (e) that moves up and down. Annular tsuba (5) on the bottom (A)
are attached integrally. An annular foot portion (to) is provided so as to engage with the inner end of this flange (2), and the pressure 7
By moving the foot (C) downward, the foot (C) can be moved downward via the flange end, thereby fixing the printed circuit board.

With the printed circuit board (2υ) fixed, move the slider downward and drill a hole by perpendicularly entering the position determined by the NC data on the printed circuit board 12D using the drill circle.

This drilling is performed after the first drilling is performed until the drill is moved to the working position, and breakage of the drill Q1) is detected at a predetermined position where the tip of the drill Q1) is separated from the printed circuit board Qυ.

This breakage detection is performed by connecting the optical fiber Ql, which is a bundle of the first optical fiber for light emission and the second optical fiber for light reception, to the third optical fiber.
Set the positional relationship that satisfies the conditions shown in the figure.

In FIG. 5, the measurement position, that is, the tip end of the optical fiber holder and the drill (manufactured by Co., Ltd.) are set in an oblique state.

That is, FIG. 6 shows the detection area in a drill rotation state of 0.3 using the optical fiber angle ψ as a parameter. ψ gradually from 0°. When increasing, the detectable area becomes Y
When ψ becomes longer in the direction (ψ=6°, 13°), and ψ is further increased (ψ=28°), the result is that it shrinks again. This phenomenon is not clear, but it seems that the flute of the drill has some influence. When ψ is changed in this way, the detectable area is greatly affected, and therefore the optimal positional relationship between the fiber and the drill tip for detecting drill breakage is also affected by ψ.

Furthermore, drilling with the above-mentioned drill Cυ generates chips, but in order to prevent these chips from adhering to the tip of the optical fiber wire, the collar (5) is removed from the side wall of the pressure foot (C). A cleaning air jet port t31J is then provided to jet cleaning air toward the tip of the optical fiber.

In this case, a suction port may be used instead of the jet port 131) to suck the chips.

Furthermore, the mounting position of the optical fiber device is set so that when the slider (2) is located at the bottom dead center, the drill (2) and the optical fiber (c) do not interfere.

Next, the operation and effect will be explained with reference to FIG.

Move the X-Y table based on the NC data.

The holes in the printed circuit board Qυ are drilled every time the position is determined.
The pressure foot (E) is lowered at the timing shown in Figure (A), and the printed circuit board Qυ is fixed by the foot portion (8).

When the foot (c) contacts and fixes the printed circuit board (2υ), lower the slider c!4) at the timing shown in Fig. 6 (B) and drill a hole at the determined position of the printed circuit board (21). do the work. After this operation, the slider (2) is raised to remove the drill, and then the 7 holes are also raised to prepare for the first drilling. In synchronization with the rising period of the slider, which is the preparation period, the power to the drill breakage detection circuit is inputted at the timing shown in FIG. 6(C). That is, light is projected onto the drill (2) from the light projecting optical fiber of the optical fiber (c) at the timings shown in FIG. 6(C) and FIG. 6(D). Drill by this light projection
The reflected light from the tip is received by a light-receiving optical fiber to detect whether or not the drill is broken.

If it is broken, the input of one reflected light will be absent or greatly reduced. This determination is converted into an electrical signal by a photoelectric conversion element (not shown) provided at the other end of the light-receiving optical fiber, and the signal is compared with a predetermined threshold value to perform six-dimensional processing and determination.

For example, it is assumed that the hole shown by the X mark in FIG. 6(B) in the second cycle breaks during work. In this case, even if the predetermined hole drilling operation cannot be performed during the work assignment period, the breakage cannot be discovered. Then, the breakage detection described above is carried out during the rising period of the slider @ after the end of the work assignment period. That is, the signal shown in FIG. 6(B) is output and the process ends.

In the above embodiment, a small-diameter drill was described, but the same effect can be obtained even if the present invention is applied to detecting breakage of a drill with a diameter of one diameter or more.

〔Effect of the invention〕

As explained above, according to the present invention, even a small diameter drill can be detected under optimal conditions.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of the device of the present invention;
Fig. 2 is an explanatory diagram of the operation of Fig. 1, and Figs. 3 to 7 are illustrations of the operation of Fig. 1.
It is an explanatory view of an example of a breakage detection system of the drill shown in the figure. 2... Drill, 3... Optical fiber group agent Patent attorney Nori Chika Ken Yudo Kikuo Takehana Figure 1 Figure 2 Fiber matters Yamagata 6 bows Figure 3 Figure 5 (A) Trill monster φ-mi (snake) Fig.4 Fig.7

Claims (3)

[Claims] (1) In a device that irradiates the tip of a drill with light from a first optical fiber, and detects breakage by receiving reflected light from the drill with a second optical fiber, the photodetector detects the light received by the second optical fiber. Drill breakage detection comprising: means for supplying a converted signal to a bandpass filter of a predetermined frequency; and means for detecting whether the output signal of the bandpass filter is a drill breakage or reflected light from dust. Device. (2) The drill breakage detection device according to claim 1, wherein the band pass filter filters a frequency around the number of blades times the rotational speed of the drill. (3) The photoelectric conversion signal received by the second optical fiber is 2
2. The drill breakage detection device according to claim 1, wherein one branch is configured as a drill breakage detection system based on the presence or absence of reflected light, and the other is configured as a detection system for detecting the presence or absence of reflected light due to dust.