JPS6159459B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for determining the quality of a cast product, and its purpose is to determine the types of several defects in a cast product and to improve the accuracy of defect inspection. be.

There are various defects in various castings. For example, during casting, there may be uneven cooling rates due to the shape of the casting, interference with shrinkage, cracks that occur during heat treatment, or excessive moisture in the mold.
When pouring hot water when the chiller is damp,
There is a problem where water vapor or gas is generated and bubbles are formed.

Furthermore, regarding spheroidal graphite cast iron, the spheroidization rate affects the quality of the casting.

As a result of testing and examining how such defects affect the natural vibration of a cast product when it is struck, the following findings were made. In other words, cracks increase the attenuation rate of the fundamental tone and upper tone group of natural vibrations. Kirai gives an envelope change to the transient waveform. When the spheroidization rate is low, the attenuation speed of the upper tone group does not change much, but the attenuation speed of the fundamental tone increases. Furthermore, the natural frequency varies depending on the type of cast product and the size of the shape even if the product is of the same type.

The present invention was invented using the above-mentioned phenomenon, and includes an amplifier circuit that hits a product, detects the resulting natural vibration sound, and amplifies the signal.
A pulse supply circuit attached to the amplifier circuit, an envelope detection circuit that detects the envelope of the entire transient waveform that determines whether the casting is objectionable, and an attenuation rate of the entire transient waveform that determines the type and shape of the casting. Equipped with an attenuation rate detection circuit, and a frequency selection and attenuation rate detection circuit that selects the frequencies of the fundamental tone and overtone, which mainly determine the cracking and spheroidization rate of a cast product, and detects the attenuation rate of the selected frequency. The present invention is characterized by a device for determining the quality of cast products.

Embodiments of the present invention will be described below with reference to the drawings. In the figure, 1 is an anechoic box, 2 is a product (cast product) suspended in the anechoic box 1 via a hanging device 3, 4 is an electromagnetic mallet for hitting this product 2, 5 is a microphone, and 6
1 is an amplifier circuit, 7 is a pulse supply circuit, 8 is an envelope detection circuit for the entire transient waveform, 9 is an attenuation rate detection circuit for the entire transient waveform, 10 is a frequency selection and attenuation rate detection circuit for the fundamental tone F, 11 is the first upper tone U ₁ frequency selection and attenuation rate detection circuit, 12 is the second upper tone
_U2 frequency selection and attenuation rate detection circuit, 13 is a programmable output circuit.

The present invention will be explained below based on FIG. That is, the product 2 is struck with an electromagnetic mallet 4 or the like, the natural vibration sound is detected by the microphone 5, the signal is amplified by the amplifier circuit 6, and the output thereof is used as the input of each circuit shown below.

(1) Envelope detection circuit 8 for the entire transient waveform.

(2) Attenuation rate detection circuit 9 that detects the attenuation rate of the entire transient waveform.

(3) Fundamental tone F, first upper tone U ₁ , second upper tone U ₂ ...
a frequency selection circuit that selects each frequency, and selected frequency attenuation rate detection circuits 10, 11, 12, etc. that detect the attenuation rate of the selected frequency.

The dislike is detected by the output detected by the envelope detection circuit 8 of the entire transient waveform. For example, when the product 2 is a cast metal cap that is attached to an insulator that suspends a power transmission line, there is an envelope fluctuation change in the range of 2 to 10 Hz. In addition, cracks are detected when the attenuation rates of the fundamental note F, the first upper note U ₁ , the second upper note U ₂ . is detected when the attenuation rate is greater than the attenuation rate of a non-defective product, and the detected signal provides a programmable test output.

Furthermore, different types of castings and items of the same type but with different sizes (for example, items with different part numbers) have different frequency spectrum distributions, so
Frequency selection circuits 10, 11, 12 for fundamental tone F, first upper tone U ₁ , second upper tone U ₂ . . . except for those with specific product numbers
The output of ... becomes non-output, and the attenuation rate of the entire transient waveform is different, so it can be distinguished.

Note that the pulse supply circuit 7 attached to the amplifier circuit 6
erases the shock pulse in the initial period (t ₀₀ to t 0 ) which is the shock waveform after the strike waveform amplified by the amplifier circuit 6, and also erases the shock pulse in the initial period (t 00 to t ₀ ) which is the shock waveform after the shock waveform is amplified by the amplifier circuit 6, and also erases the shock waveform (transient waveform) excluding the shock waveform at each attenuation. The attenuation rate measurement is started with a time lag in consideration of the time (t ₀ to t ₁ ) until reaching the rate measurement circuit, and the circuit provides the attenuation rate measurement time (t ₁ to t ₂ ). Next, the apparatus of the present invention will be explained with reference to FIGS. 2 and 3. The product 2 to be inspected is struck, the resulting vibration sound is detected by the microphone 5, and the microphone output is amplified by the amplifier circuit 6. This vibration waveform is shown in c in FIG. Then, a part of it is passed through a differentiating circuit 14 to adjust the waveform, and a delay circuit 15 divides the waveform at each time t ₀ , t ₁ , with respect to the initial t ₀₀ .
A delayed pulse b of t ₂ is produced. From t ₀₀ to t ₀ , gate circuit 1 is installed in the signal system to eliminate the impact pulse of the hitting sound.
6 to obtain a transient waveform A with the impact pulse eliminated. This transient waveform A is divided into the entire transient waveform, the fundamental tone F, the first upper tone U ₁ , the second upper tone U _{2 .} . . components to form individual channels.

That is, the entire transient waveform is rectified by a rectifier circuit 17, passes through a low-pass filter 18 of about 200 Hz, and then passes through a band filter 19 for detecting envelope changes of the entire transient waveform. Then, the output 21 rectified by the rectifier circuit 20 is detected.

In addition, the fundamental tone F, the first upper tone U ₁ , the second upper tone U ₂ ... are the fundamental tone F, the first upper tone when the cast product is of good quality.
It passes through variable frequency selection filters 22, 23, etc. set to U ₁ , second upper tone U ₂ .

Further, each level adjuster is also determined in advance in consideration of the operation of the apparatus.

Then, after each channel other than the channel for detecting the envelope change of the entire transient waveform is rectified by the rectifier circuits 24, 25, etc., each spectral component is about 1 KHz, and if it is higher than that, then
Comparison circuit that compares the attenuation rate between t ₁ and t ₂ using a reference voltage having a ratio to sample hold 28, 29, 30... and peak hold levels 31, 32, 33... through low-pass filters 18, 26, 27... of about 200 Hz. 34, 35, 36, and so on.

Sample and hold is performed twice at t ₁ and t ₂ to obtain the steps shown in Figure 3, but since the peak hold is at the level obtained at t ₁ , the transient waveform and the degree of attenuation of the envelope of each frequency component are calculated as follows: can be determined regardless of the absolute level of The outputs passed through each comparison circuit can be judged to be good or bad based on typical programmable conditions as shown in FIG. That is, 1 in FIG. 3 represents the operation when the attenuation speed at _t2 is greater than the good product setting value, and 0 represents the opposite condition to 1.

In addition, the frequency spectrum distribution of different types of cast products and of the same type but different sizes (for example, different part numbers) is different, so the fundamental tone F and the first upper tone are different.
The outputs of the frequency selection circuits for U ₁ , second upper tone U _{2 .} . . become non-output, and the attenuation rates of the entire transient waveforms are different.

In this example, it is possible to distinguish cracks and dents, which are particularly serious defects among casting products, and the degree of spheroidization of cast cavities and spheroidized graphite cast iron, without requiring manual labor, as well as to determine the type of casting products and the degree of spheroidization of spheroidal graphite cast iron. However, it is also possible to distinguish between items of different sizes (for example, items with different product numbers). In other words,
According to the present invention, there are excellent effects such as being able to determine the type of product defect, the difference in type, and the same type of defect but with different sizes, and that the determination can be made without the need for manpower.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a block diagram showing an embodiment of the invention, and FIG. 3 is a chart showing waveforms of various parts and typical programmable output conditions according to the invention. DESCRIPTION OF SYMBOLS 1... Anechoic box, 2... Product, 3... Hanging tool, 4... Electromagnetic mallet, 5... Microphone, 6... Amplification circuit, 7... Pulse supply circuit, 8... Envelope detection circuit, 9...
Attenuation rate detection circuit, 10, 11, 12... Frequency selection and attenuation rate detection circuit, 13... Programmable circuit.

Claims (1)

[Claims] 1. An amplifier circuit that detects the natural vibration sound generated by striking a product and amplifies the signal, a pulse supply circuit attached to the amplifier circuit, and an envelope of the entire transient waveform that determines whether the casting product is objectionable. An envelope detection circuit that detects, an attenuation rate detection circuit that detects the attenuation rate of the entire transient waveform that determines the type and shape of the casting, and a fundamental and overtone that mainly determines cracks and spheroidization of the casting. A device for determining the quality of a cast product, comprising a frequency selection and attenuation rate detection circuit that selects a frequency and detects an attenuation rate of the selected frequency.