JP5420437B2 - Powder detector - Google Patents

Description

  The present invention relates to a powder detection device that detects the presence or amount of powder such as cutting powder passing through a duct by cutting with a drill or the like, and dust passing through the duct with a dust collector or the like.

  A large number of holes must be drilled in the printed circuit board for mounting electrical components, and drilling is performed. These processing apparatuses are being automated, and detection of breakage due to wear of a drill is indispensable for minimizing the occurrence of defective products. Conventionally, a method shown in the following Patent Document 1 has been developed as one method of detecting breakage of a drill.

  In this method, the cutting powder detector detects that cutting powder passes through the duct during machining, and if there is no output from the detector during machining, it is determined that the drill is broken, and the breakage is detected. Yes. As one method for configuring the cutting powder detector, an optical detection device including a set of light sources and light receivers is used.

  This detection device detects the presence or absence of cutting powder by irradiating the cutting powder passing through the duct with the light emitted from the light source and measuring the change in the output of the light receiver placed at the position through which the cutting powder enters. Device.

  FIG. 4 is a block diagram showing such a conventional optical detection device and a cutting device for drilling a printed circuit board using the same. In FIG. 4, a drill 12 is attached to a drilling machine 11 for drilling a printed circuit board 14 or the like, and the printed circuit board 14 installed on the moving stage 13 is moved to a predetermined position according to a set program. However, many holes are formed by repeating the drilling operation. Here, the cutting powder 19 generated with the drilling is sucked and discharged by the duct 15 provided with an opening in the vicinity of the drill. A light detection device 20 for detecting cutting powder is provided in the middle of the duct. The light detection device 20 includes a transparent tube 21 for transmitting light provided in the detection unit 16 of the duct, a light source 22 disposed opposite to the transparent tube 21, a light receiver 23, a light source 22, and a light receiver. And a housing 24 provided with a hole into which the transparent tube 21 is inserted.

  The output of the light receiver 23 is input to the signal processing device 25. The signal processing device 25 detects the change in the output voltage of the light receiver 23, and determines the number of times that the amount of change in the output voltage of the light receiver 23 exceeds a certain threshold. Means for detecting are provided.

  Such a method of detecting the presence or absence of cutting powder from the duct has a feature that the detection apparatus is easy to install because the duct is usually already installed in the cutting apparatus. Further, since the optical system is simple and a light emitting diode can be used as a light source and a photodiode can be used as a light receiver, the detection device can be realized at low cost.

Japanese Examined Patent Publication No.59-43262

  Recently, there is an increasing demand for high-precision machining with a small hole diameter. For this reason, the size of the cutting powder to be detected is small and the amount thereof is often small. Therefore, the above-described conventional detection apparatus has insufficient sensitivity, and the applicable range is limited, and the processing circuit and apparatus become complicated and expensive to improve the sensitivity. There is.

  Furthermore, the conventional apparatus detects whether the drill is broken or broken depending on the presence or absence of cutting powder, and the breakage cannot be detected unless the drill is broken. If the breakage of the drill occurs during the machining, the work piece will also be damaged, resulting in a defective product, and exchanging the drill after the breakage takes a processing time. Generally, since the size and amount of cutting powder change when the drill before breakage is deteriorated, if the sensitivity of the detection device can be improved, the deterioration state can be detected, and the drill can be replaced before breakage. Moreover, if a highly sensitive and inexpensive powder detection device is obtained, it can be applied to detection of other powders such as a dust collector.

  Accordingly, an object of the present invention is to provide a powder detection device that is more sensitive and less expensive than a conventional cutting powder detection device.

  In order to solve the above problems, a powder detection apparatus according to the present invention is a powder detection apparatus that detects at least one of the presence or the amount of powder passing through a certain area, and a plurality of light sources that irradiate the area with light. A plurality of light receivers that receive the respective lights that have passed through the region, means for detecting a change in the output voltage of the light receiver due to the powder passing through the region, and a change amount of the output voltage. Means for detecting the number of times exceeding a certain threshold value, and the emission directions of the plurality of light sources are not parallel to each other, and the emission light from the plurality of light sources irradiates substantially the same portion in the region. And

  Here, the light source may include a light emitting diode, and the light receiver may include a photodiode.

  The certain area may be in a transparent tube. In this case, the plurality of light sources and the plurality of light receivers may be fixed to one housing having a hole into which the outer shape of the transparent tube is fitted.

  Further, a change in output voltage obtained by connecting outputs of the plurality of light receivers in parallel may be detected.

  The present invention has been completed as a result of experiments conducted by the inventors to improve the sensitivity of a conventional cutting powder detection device. In the conventional detection device, the sensitivity can be improved by increasing the intensity of the light source. However, the effect of improvement is not sufficient because of sensitivity saturation and the influence of noise. In addition, improvements can be obtained by using a plurality of light sources and light receivers, irradiating light from the same direction to the area through which the cutting powder in the duct passes, and receiving and detecting each with the light receivers. Even if the number of photo detectors was increased, sufficient sensitivity could not be obtained.

  On the other hand, as in the present invention, a plurality of light sources having different emission angles such that the emitted light illuminates substantially the same portion in the duct is used, and the emitted light passes through the light source. It has been found that the detection sensitivity is greatly improved by installing a plurality of light receivers at each incident position and detecting them. The reason is estimated as follows.

  The principle of the cutting powder detection device is to detect the passage of the cutting powder by the change in the amount of light when the irradiation light is blocked by the passage of the cutting powder and enters the light receiver. When a plurality of light sources and corresponding light receivers are used, even if a plurality of light sources and light receivers are simply arranged side by side and different portions in the duct are irradiated as in the past, strictly speaking, the light receivers corresponding to them are not arranged. Since each output voltage becomes a signal having different information for the cutting powder, the effect of improving the sensitivity is small even if these detection signals are added. This is because when the cutting powder passes through the duct, it is considered that the distribution of the cutting powder varies depending on the location and time in the duct. On the other hand, in the present invention, since the same portion in the duct is simultaneously irradiated with light from different directions and detected, the output voltages of the plurality of light receivers have almost the same information with respect to the cutting powder, and their addition This greatly improves the sensitivity.

  Further, the cutting powder has a powder shape that is very different from a sphere, and has an asymmetric and complicated shape such as a flat shape, and the shape varies greatly depending on cutting conditions and in time. Therefore, when light is irradiated into the duct from a certain direction, even if the size and amount of the cutting powder that passes through the duct are the same, the amount of light that is cut off depends on the direction of the cutting powder. It is estimated that there are cases where the change is small.

  On the other hand, in the present invention, since the same part in the duct is simultaneously irradiated with light from different directions and detected, the change in output voltage is averaged and stabilized throughout the plurality of light receivers. Stable sensitivity can be obtained by adding the output voltage as it is or through an amplifier.

  As described above, according to the present invention, it is possible to obtain a powder detection device that is more sensitive and less expensive than a conventional cutting powder detection device.

It is a block diagram which shows one Embodiment of the powder detection apparatus by this invention. It is a figure which shows the structure of the light source in this Embodiment, a light receiver, and a signal processing circuit. It is a figure which shows the light source and light receiver which were fixed to one housing | casing which is one Example of this Embodiment, Fig.3 (a) is a plane sectional view, FIG.3 (b) is FIG.3 (a). It is AA side sectional drawing. It is a block diagram which shows the conventional optical detection apparatus and the cutting apparatus for drilling a printed circuit board using the same. It is a figure which shows the other structure of the light source in this Embodiment, a light receiver, and a signal processing circuit.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing an embodiment of a powder detection apparatus according to the present invention. In FIG. 1, the powder detection device of the present embodiment is a powder detection device that detects at least one of the presence and the amount of powder 33 passing through a certain region in a cylinder 32 such as a duct. Two light sources 34 and 35 for irradiating light into the cylinder 32, and respective outgoing lights 38 and 39 from these light sources enter a predetermined region of the cylinder 32, and receive the respective lights passing therethrough Two light receivers 36 and 37 are arranged. Furthermore, the apparatus includes means for detecting changes in the output voltage of the light receivers 36 and 37 due to the powder 33 passing through the cylinder 32, and means for detecting the number of times the amount of change in the output voltage exceeds a certain threshold value. So that the emission directions of the two light sources 34 and 35 are not parallel to each other, and the emission lights 38 and 39 from these light sources irradiate substantially the same portion 40 in the cylinder 32. It is configured.

  Here, the light sources 34 and 35 each include a light emitting diode, and the light receivers 36 and 37 each include a photodiode.

  The tube 32 may be a transparent tube, or a transparent window through which light passes may be provided in the tube 32. In addition, the two light sources 34 and 35 and the two light receivers 36 and 37 may be fixed to one housing having a hole into which the outer shape of the cylinder 32 is fitted.

FIG. 2 is a diagram showing the configuration of the light sources 34 and 35, the light receivers 36 and 37, and the signal processing circuit 25 in the present embodiment. In FIG. 2, light sources 34 and 35 are each composed of a light emitting diode 1 and its drive circuit 2, and light receivers 36 and 37 are each composed of a photodiode 3 and an amplifier circuit 4. The output of each photodiode 3 is amplified by the amplifier circuit 4 and input to the signal processing circuit 25. The outputs of the amplifier circuits are combined and added at the input stage of the signal processing circuit. The added output is input to the comparator 6. When the powder passes between the light emitting diode 1 and the photodiode 3, the output voltage of the photodiode 3 is reduced by the passing time. Therefore, the waveform output from the amplifier circuit 4 after removing the DC component is the size of the powder. A pulse-like waveform with a width determined by the passing speed is obtained. When the powder is cutting powder in a duct, the pulse width is usually about several μs to several hundreds μs. In the comparator 6, the amount of change in the output voltage of the amplifier circuit, that is, the height of the pulse is compared with a predetermined threshold value, the number of pulses exceeding the threshold value is counted by the counter 8, and the result is determined by the determination processing circuit. Sent to 9. The determination processing circuit 9 outputs the presence or absence of powder or the amount of powder calibrated by comparison with a predetermined value.

  When detecting cutting powder in a duct as a device for detecting breakage or deterioration of a drill, the number of pulses counted as described above and the fluctuation amount of the number of times per drilling are within a predetermined deterioration reference number range. Then, it is compared with the range of the predetermined deterioration reference fluctuation amount, and information on the deterioration or breakage of the drill is output as a result.

  In this embodiment, the outputs of the two light receivers 36 and 37 are added and output. In this case, the outputs of these light receivers are connected in parallel and input to the signal processing circuit 25. Alternatively, as shown in FIG. 5, the amplifier circuit 4 may be shared, and two photodiodes of the light receivers 36 and 37 may be connected to one amplifier circuit 4. Similarly, two light emitting diodes of the light sources 34 and 35 may be connected to one drive circuit 2.

  In the above embodiment, the number of light sources and light receivers is two. However, the sensitivity can be further improved by using three or more light sources and light receivers.

  Next, specific examples of the powder detection device according to the above embodiment will be described.

  FIGS. 3A and 3B are diagrams showing a light source and a light receiver fixed to one housing which is an example of the above-described embodiment. FIG. 3A is a plan sectional view, and FIG. It is AA side surface sectional drawing of 3 (a). The present embodiment is a powder detection device that can be used in the cutting powder detection device of the cutting device for drilling a printed circuit board shown in FIG. 4, and in FIG. 3, two light sources 34 and 35 and two light receivers are used. 36 and 37 are fixed to one housing 45 having a hole into which the outer shape of the transparent tube 21 used in the conventional photodetector shown in FIG. 4 is fitted. The casing 45 is provided with two sets of cavities 46 and 47 facing each other with the transparent tube 21 interposed therebetween, and a light source 34 and a light receiver 36, and a light source 35 and a light receiver 37 are installed at both ends of the cavities 46 and 47. Has been. With this arrangement, the light emitted from the two light sources 34 and 35 irradiates substantially the same central portion 48 in the transparent tube 21, and the transmitted light enters the light receivers 36 and 37, respectively.

  The cutting powder detection device according to the above-described embodiment was prototyped and compared with the sensitivity of the conventional detection device using two sets of light sources and light receivers. Obtained.

  As described above, according to the present invention, it was confirmed that a powder detection device having higher sensitivity than the conventional cutting powder detection device and capable of being configured with inexpensive components as in the conventional components can be obtained. .

  Needless to say, the present invention is not limited to the above-described embodiments and examples, and the number, arrangement, and shape of light sources, light receivers, and housings according to the powder detection device to be applied. It is possible to change the design of the configuration. In the case where a certain region through which the powder passes is large, the light source and the light receiver can be mounted separately in separate housings.

DESCRIPTION OF SYMBOLS 1 Photodiode 2 Drive circuit 3 Photodiode 4 Amplification circuit 6 Comparator 8 Counter 9 Judgment processing circuit 11 Drilling machine 12 Drill 13 Moving stage 14 Printed circuit board 15 Duct 16 Detection part 19 Cutting powder 20 Photodetector 21 Transparent tube 22, 34 , 35 Light source 23, 36, 37 Light receiver 24, 45 Housing 25 Signal processing circuit 32 Tube 33 Powder 38, 39 Emission light 40 Portions 46, 47 Cavity

Claims (5)

A powder detection apparatus that detects at least one of the presence or the amount of powder passing through a certain region and the amount thereof, and irradiates light beams from a plurality of directions that are not parallel to each other so as to cross substantially the same partial region of the region A light source, a plurality of light receivers for receiving the respective light beams that have passed through the partial area, a coupling means for combining the output levels of the plurality of light receivers, and a light beam by passing the powder through the partial area. means part to detect a change in the output level of said coupling means generated upon interruption of, seen including a means for detecting the number of times that the amount of change in the level exceeds a certain threshold, the light source comprises a light emitting diode The powder detector includes a photodiode . The powder detection apparatus according to claim 1, wherein the certain region is in a transparent tube. 3. The powder detection device according to claim 1, wherein the plurality of light sources and the plurality of light receivers are fixed to one housing having a hole into which an outer shape of the transparent tube is fitted. . The powder detection apparatus according to claim 1, wherein the coupling unit includes an amplifying unit that amplifies the outputs of the photodiodes together. Based on the output of the means for detecting the number of times, the number of times in the unit machining operation and the amount of change in the number of times between the unit machining operations are measured, and the number of times in the unit machining operation and the amount of fluctuation in the number of times between the unit machining operations 5. The method according to any one of claims 1 to 4, further comprising: processing determination means for determining whether or not each is within a predetermined number of times range and a predetermined number of fluctuation ranges. The powder detection apparatus as described.

Images