JPH0612251B2 - Screw inspection device and inspection method using the device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a screw inspection device for selecting screws that are aligned and transferred, and a screw inspection method using the device.

<Prior Art> Conventionally, the inspection of the presence or absence of threads in a screw inspection device and its inspection method has been performed by the method shown in FIG.
In FIG. 10, reference numeral 100 denotes a detection unit having a light emitting unit and a light receiving unit built therein, and the light from the detection unit 100 has an incident angle of 90 at the thread of the screw 102 aligned and transferred by the chute 101. It is projected so that it will be inspected. In this inspection, correctly cut threads are specularly reflected and the light returns in the direction of the same axis as the projected light (the tenth).
(A)), however, the amount of returning light is reduced for defective ones (Fig. 10 (B)).

That is, in the conventional screw inspection apparatus and inspection method for the presence or absence of a thread, the return light amount is measured, and a good or defective screw is selected depending on the amount of the light amount.

<Problems to be Solved by the Invention> However, since the conventional screw inspection device and inspection method utilize the amount of light reflection, not only the thread shape but also the color and surface condition of the thread are greatly affected. The problem is that unless the work is affected and the surface condition is exactly the same, it is not possible to determine the quality of the screw thread, and the difference in the screw thread (difference between the metric thread and the tapping screw) cannot be measured at all. There was a point.

<Means for Solving Problems> The present invention has been made in view of the above circumstances, and is not affected by the color and surface state of the work, and the quality of the thread or the difference in thread depending on the type of thread. Can be measured stably,
It is also an object of the present invention to provide a screw inspection device and inspection method capable of simultaneously measuring the external shape of the screw such as the length under the neck of the screw, the tip shape of the screw and the head shape of the screw with the same sensor.

The present invention relates to the first invention in order to achieve the above object.
The screw inspection device places screws that are aligned and transferred in the transfer path.
Corresponding to the above-mentioned screw status by detecting with the detector provided in
Input measurement signal to the central processing unit, and
Inspection device that selects screws by comparing with the reference value set for
Position, the detection unit should face the transfer path.
The light source and part of it were used as the timing signal transmitter
It consists of an imaging camera with a built-in one-dimensional image sensor.
Relationship between the screw that passes through and the one-dimensional image sensor
The output signal from this one-dimensional image sensor
Transposed into a waveform showing the number of threads, the thread interval and the length under the neck
This enables you to obtain the appearance signal of the screw and inspect the screw.
According to a second aspect of the present invention, there is provided a screw inspection method including a light source and a one-dimensional image.
A screw between the camera and the imaging camera with the built-in image sensor
The position of the screw and the one-dimensional image sensor
The output signal from this one-dimensional image sensor is
Number, screw thread interval and under neck length
Generate a screw appearance signal from the image camera and
Signal is first input to the timing measurement section and a timing signal is generated.
In addition to recognizing with a timing signal, next
The visual signal is input to the external appearance measurement section of the screw, and the
The maximum, minimum, and average values related to appearance are calculated using the Unta
On the other hand, when the screw is not recognized by the above timing signal,
Stopped the measurement and calculation circuits of the above appearance measurement unit
Input each measurement and calculation result of the
Selecting screws by comparing the force result with the judgment value already input
Is characterized by.

<Example> Hereinafter, the present invention will be described in detail based on examples shown in FIGS. 1 to 9.

FIG. 1 (A) shows an outline of the entire screw inspection apparatus according to the present invention. Reference numeral a is a parts feeder from which a screw 1 is supplied to a stepped roll conveyor b. This stepped roll conveyor b is configured by arranging rollers having a large diameter portion b ₁ and a small diameter portion b ₂ in parallel in the axial direction, and selects the screw 1 according to the size of the head diameter. That is, a screw having a small head diameter is dropped between the two rollers and discharged to the outside of the system, and the other screws 1 are dropped from the small diameter portion b ₂ to be sent to the transport mechanism of the next stage. The conveying mechanism c at the next stage is configured by arranging two conical rollers whose diameters are gradually reduced in the axial direction in parallel, and the screw 1 sent to this is aligned and transferred in the gradually decreasing direction of the conical rollers. After that, the screw 1 is sent to the measuring section d. A screw 1 in this measuring section is hung on a conveyor belt 2 in a hanging state, and an optical guide 3 using an optical fiber as a light source for a camera is provided on both sides of the belt 2 as shown in FIG. 1 (B). An image pickup camera 5 having the one-dimensional image sensor 4 therein is installed. In the measuring section d, the screw 1 is measured for various factors,
Upon receiving the measurement signal, the sorting section e sorts the good product f and the bad product g.

As shown in FIG. 4, the imaging camera 5 has a timing measuring unit 6 to which an output signal from the camera is inputted and a screw appearance measuring unit for measuring the number of screw threads, the screw thread interval and the length under the neck. 7 and 7 are connected. The timing measuring unit 6 is necessary as a sensor for knowing that the screw to be inspected has entered the measuring unit, and a part of the one-dimensional image sensor 4 is taken out as a single photo sensor signal and input to the timing measuring unit 6. There is. The timing measuring unit 6 and the screw appearance measuring unit 7 are each connected to a central processing unit (CPU) 8, and a signal is sent from the CPU to the CPU 8 to select a defective screw product. 9 is connected.

As shown in FIGS. 2A to 2E, the one-dimensional image sensor 4 is provided with addresses 1 to n. Therefore, when the screw 1 to be measured moves in front of the one-dimensional image sensor 4 in the direction of the arrow (to the left in the drawing), the positional relationship between the screw 1 and the image sensor 4 ((A)
(Shown in (E)), the output signal from the one-dimensional image sensor 4 changes to the waveforms shown in (F) to (J). Here, a indicates the number of threads, b indicates the thread interval, and c indicates the length under the neck. By measuring these a, b, and c, it is possible to identify the quality or difference of the screws. Further, the time variation of the under-neck length c is measured, and the maximum value, the minimum value, the average value, etc. are calculated to obtain the tip shape of the screw (Figs. 3 (A), (B), (C )) And the head shape can be discriminated at the same time.

FIG. 4 is a block diagram showing an outline of the whole of the inspection apparatus, and an actual screw measuring method will be described based on this block diagram.

The output signal from the one-dimensional image sensor camera 5 is input to the timing measuring unit 6 and the screw measuring unit 7 via the amplifier 11. The timing measuring unit 6 acts as a sensor for knowing that the screw 1 to be measured has entered the measuring position, the details of which are shown in FIG. That is, the output signal from the image sensor camera 5 is input to the sample hold circuit 12 via the amplifier 11. Separately from this, in order to specify a place to be taken out from the camera signal as a single sensor, the output signal from the buffer 13 is converted into a hold pulse by the address counter 14 and the digital comparator 15, and this is input to the sample hold circuit 12. Let This hold pulse can be arbitrarily adjusted by the CPU 8 because the comparison part of the digital comparator 15 is connected to the CPU 8 via the register 16 for adjusting the screw portion which takes timing. In the sample hold circuit 12, the output signal from the image sensor camera 5 input via the amplifier 11 and the above hold pulse are superposed in an analog manner to hold the peak voltage to obtain the voltage from the single sensor at the measurement point. Extracting. The output signal as a single sensor from the sample hold circuit 12 thus taken out is binarized by the analog comparator 18 via the low-pass filter 17 installed for noise prevention, and then input to the CPU 8. To be done. Further, in the timing measuring section 6, the threshold level of the analog comparator 18 is also set by the CPU 8 to D
It can be controlled via the / A converter 19. With the above-described configuration, the timing signal output from the timing signal transmission unit provided in the one-dimensional image sensor is
It recognizes the screws in the transfer path and also commands the adjustment of the screw parts that take timing, that is, the adjustment for specifying the screw parts to be taken out as a single sensor from the output signal from the imaging device.

The output signal from the image sensor camera 5 input to the screw appearance measuring unit 7 via the amplifier 11 is, as shown in FIG. 4, passed through the A / D converter 20 to a digital filter 21 for eliminating optical noise. Entered in. With the digital filter 21, processing such as removal of isolated points can be performed without sacrificing dimensional accuracy.

In general, when performing isolated point removal or the like, it is often done by configuring a low-pass filter in an analog or digital manner. When this conventional low-pass filter is used as a filter for removing isolated points of the present apparatus, the low-pass filter causes a delay in the rise of voltage, which causes an error in the dimensional accuracy of the screw. Therefore, in this device, as shown in FIG. 6, an error occurs in the screw dimension accuracy by combining the 8-bit shift register 22 and the filter conversion ROM 23 in a serial line to form a real-time digital filter. The isolated points are removed so as not to exist. For details, see Fig. 7 (A), (B),
As shown in FIG. 7C, the conversion pattern for each pattern is stored in the filter conversion ROM 23 so that isolated points are removed or the rising position is constant, and the ROM 23 is converted in real time.

The output signal from the digital filter 21 is directly sent to the screw thread number counter 26 and is sent to the screw thread interval counter 27 by A.
The AN under the neck length counter 28 is connected via the ND circuit 24.
The data is input through the D circuit 25, converted into data, and input to the data processing circuit 46. More specifically, the data-converted output signal from the thread number counter 26 is input to the CPU 8 through the maximum value calculation circuit 29 and the buffer 33.
The output signal from the thread interval counter 27 is a buffer 46.
Is input to the CPU 8 via. Neck length counter 28
The output signal from the maximum value calculation circuit 30, the minimum value calculation circuit 31, the average value calculation circuit 32 and the buffers 34, 35, 36
Is input to the CPU 8 via.

FIG. 8 is a detailed diagram showing the configuration of the data processing circuit 46. The maximum value calculation circuits 29 and 30 compare the input data A and the data B previously input to the registers 40 and 41 by the comparators 37 and 38. By comparison, the maximum value is calculated by refreshing the registers 40 and 41 to the input data A only when the input data A is larger than the data B. On the contrary, the minimum value calculation circuit 31 refreshes the register 42 to the input data A only when the input data A is smaller than the preset data B to calculate the minimum value. Further, the average value calculation circuit 32 calculates and calculates the integrated value of the measurement data and the number of times of measurement by the integrator 43 and the counter 44, respectively, and inputs the data to the divider 45.

FIG. 9 is a flowchart showing an inspection method using the present apparatus configured as described above, and one inspection routine is as follows. That is, when the screw to be inspected enters the screw measuring unit, the timing signal is turned on to clear and preset each calculation circuit of the screw appearance measuring unit to start measurement and calculation. Next, when the screw passes through the screw measuring section, the timing signal is turned off and the above measurement and calculation are terminated, and the measurement and calculation results are compared with preset judgment reference data. Then, check whether each of the measured and calculated values is within the range of non-defective products by checking each item such as the number of threads, the thread interval, and the length under the neck. If so, an ejection signal is sent to the sorting section to end one routine.

<Advantages of the Invention> Therefore, the present invention is that the screw thread is correctly measured without being affected by the color and surface condition of the screw, and the screw thread is not only good or bad as in the prior art but also the screw thread is different (for example, metric thread). And the tapping screw) can be measured, the screw thread, the length under the neck, and the tip shape can be measured with one imaging camera. Furthermore, since the sensor is provided inside the imaging camera, measurement is possible. Since it is not necessary to use a separate sensor for the timing for use, there is an effect that problems such as sensor mounting locations do not occur.

Further, according to the screw inspection method of the present invention, not only the external shape of the screw is selected, but also the function as a line sensor is recognized to recognize the screw that has entered the measuring section.

[Brief description of drawings]

FIG. 1 shows a screw inspection device of the present invention, (A) is an overall schematic diagram thereof, (B) is a schematic diagram showing a measuring section of the same, and FIGS. 2 (A) to (J) are camera output signals. Waveform transition diagram, third
(A) to (C) are diagrams for detecting the tip shape of a screw, FIG. 4 is a block diagram showing an outline of a screw inspection device of the present invention, and FIG. 5 is a block diagram showing a configuration of a timing measuring unit, and FIG. Is a digital filter circuit diagram, FIG. 7 is a filter principle diagram, FIG. 8 is a block diagram of a data processing circuit, FIG. 9 is a flowchart diagram showing a screw inspection method, and FIGS. 10 (A) and 10 (B).
Shows a conventional screw inspection device. 1 ... screw, 2 ... belt, 3 ... light guide (light source),
4 ... One-dimensional image sensor, 5 ... Imaging camera (imaging device), 6 ... Timing measuring unit, 7 ... Screw appearance measuring unit, 8 ... Central processing unit (CP)
U), 9 ... Sorting unit, 17 ... Low-pass filter, 21
...... Digital filter, 22 ...... Shift register, 23
... ROM for filter conversion, 26 ... screw thread number counter, 27 ... screw thread interval counter, 28 ... under neck length counter, 46 ... data processing circuit

Claims (2)

[Claims] 1. A screw that is aligned and moved is detected by a detector provided facing a transfer path, and a measurement signal corresponding to the state of the screw is input to a central processing unit, and this input signal and a preset signal are set. In an inspection device that selects screws by comparing with a reference value, for imaging with a light source provided with the detection unit facing each other across the transfer path and a one-dimensional image sensor having a part as a timing signal transmission unit It consists of a camera and
Depending on the positional relationship between the passing screw and the one-dimensional image sensor, the output signal from this one-dimensional image sensor is transformed into a waveform showing the number of threads, the thread interval, and the length under the neck. A screw inspection device characterized by obtaining and inspecting a screw. 2. A screw is passed between a light source and an imaging camera having a built-in one-dimensional image sensor, and an output signal from the one-dimensional image sensor is detected by a positional relationship between the screw and the one-dimensional image sensor. The appearance signal of the screw is generated from the imaging camera by changing to a waveform showing the number, the thread interval, and the length under the neck, and the appearance signal is first input to the timing measuring unit to generate the timing signal and recognized by the timing signal. When the above appearance signal is input to the appearance measuring section of the screw, the maximum, minimum, and average values related to the appearance are calculated by the counter in the measuring section, while the screw is not recognized by the timing signal. Stops the measurement and calculation circuit of the appearance measurement unit, inputs the previous measurement and calculation results to the central processing unit, and compares the input results with the already input judgment values to select screws. Inspection method of the screw, characterized in Rukoto.