TWI660050B - Simple stress relief method and device - Google Patents

Abstract

A simple stress relief device comprising a vibrator transmitting vibration waves to a workpiece at a vibration frequency between 1H _Z to 100H _Z , a sensor for sensing amplitude and vibration frequency, and outputting a voltage signal, and A spectrum analyzer electrically connected to the sensor. The spectrum analyzer uses the Fourier transform operation to obtain the frequency spectrum of the resonance wave according to the amplitude and vibration frequency included in the voltage signal, and separates the resonance wave in the frequency domain between 250 HZ ~ 1750HZ to obtain the maximum corresponding resonance wave. The vibration frequency at the amplitude is used as a rated vibration frequency of the exciter, so that the exciter continues to generate vibration at the rated vibration frequency, thereby eliminating the residual stress of the workpiece. With this, the present invention uses the aforementioned special wave band resonance wave to improve the elimination ratio of residual stress, and uses the special analysis and calculation method of the spectrum analyzer to automatically calculate the optimal rated vibration frequency, and further enhance and determine the rated vibration. Speed and accuracy of frequency.

Description

Simple stress relief method and device

The invention relates to a stress relief method, in particular to a simple stress relief method and device for eliminating residual stress by vibration.

Residual stress is common in workpieces that undergo different processing procedures such as casting, rolling, cold working, heat treatment, welding, etc. However, this residual stress is likely to cause defects and damage to the workpiece, which is a subject that must be paid much attention to in order to improve quality. There are many traditional methods for eliminating residual stresses in workpieces, which can be roughly divided into two types: heat treatment and mechanical treatment.

The method of removing residual stress by mechanical means is represented by hammering (Peening), which is mainly to hammer the bead of the weldment to cause compressive stress on the bead surface to eliminate the tensile stress remaining on the bead. However, this method has more practical experience than scientific data, and it has the disadvantages of difficult control and uncontrollable accuracy.

There is another method to eliminate residual stress of the workpiece by vibration, such as the Republic of China Patent No. I281502, I287042, I314489, I418636, and Application No. 201235486. , Driving the displacement (dislocation) movement, to achieve the purpose of eliminating residual stress.

Among them, during vibration, part of the energy will be consumed by the beat of the workpiece, and the other part of the energy will be used for the internal fluctuation of the workpiece. The larger the fluctuation, the greater the contribution to the stress relief. However, because the energy of the wave directly affects the effect of eliminating residual stress, and the aforementioned prior technology mainly uses an oscilloscope to manually find the amplitude and frequency of the required vibration wave, so how to cooperate with different situations when there are errors in manual interpretation The workpiece, which accurately obtains the proper amplitude and frequency, and further enhances the effect of stress relief, has become the goal of the inventor of this case.

Therefore, an object of the present invention is to provide a simple stress relief method and apparatus capable of improving the effect of residual stress relief in a simple manner.

Therefore, the simple stress relief method of the present invention uses a stress relief device as a tool. The stress relief device includes an exciter transmitting vibration waves to a workpiece at a vibration frequency between 1H _Z and 100H _Z , and the workpiece. A sensor connected and sensing amplitude and vibration frequency, and a spectrum analyzer electrically connected to the sensor. The simple stress relief method includes the following steps:

Step a: The spectrum analyzer receives a voltage signal from the sensor, and the voltage signal includes a sensed amplitude and a vibration frequency;

Step b: The spectrum analyzer obtains the frequency spectrum of the resonance wave by performing a Fast Fourier Transform (FFT) operation according to the amplitude and vibration frequency in the foregoing voltage signal;

Step c: The spectrum analyzer separates resonance waves in the frequency domain between 250 HZ and 1750HZ;

Step d: The spectrum analyzer obtains the vibration frequency corresponding to the maximum amplitude of the resonance wave; and

Step e: The spectrum analyzer uses the vibration frequency of step d as a rated vibration frequency of the shaker, so that the shaker continuously generates vibrations at the rated vibration frequency, and transmits the vibration wave to the workpiece.

A simple stress relief device includes an exciter, a sensor, and a spectrum analyzer.

The exciter transmits a vibration wave to a workpiece at a vibration frequency between 1HZ and 100HZ.

The sensor is connected to the workpiece and is used for sensing amplitude and vibration frequency, and outputs a voltage signal including the amplitude and vibration frequency.

The spectrum analyzer is electrically connected to the sensor, and performs a Fast Fourier Transform (FFT) operation according to the received voltage signal to obtain the frequency spectrum of the resonance wave, and separates the resonance in the frequency domain between 250 HZ ~ 1750HZ To obtain the vibration frequency corresponding to the maximum amplitude of the resonance wave, and use it as a rated vibration frequency of the exciter, so that the exciter continuously generates vibration at the rated vibration frequency, and transmits the vibration wave to the workpiece .

The effect of the present invention is: using the aforementioned special wave band resonance wave to improve the elimination ratio of residual stress, and using the special analysis and calculation method of the spectrum analyzer to automatically calculate the optimal rated vibration frequency, and further enhance and determine the rated vibration Speed and accuracy of frequency.

Referring to FIG. 1, an embodiment of a simple stress relief device 1 according to the present invention includes: an exciter 11, a sensor 12, and a spectrum analyzer 13.

The exciter 11 transmits a vibration wave to one workpiece 2 at a vibration frequency between 1HZ and 100HZ.

The sensor 12 is connected to the workpiece 2 and is used for sensing amplitude and vibration frequency, and outputs a voltage signal V including the amplitude and vibration frequency. The sensor 12 is an accelerometer in this embodiment.

The spectrum analyzer 13 is electrically connected to the exciter 11 and the sensor 12 in this embodiment.

It is worth noting that, in this embodiment, the exciter 11 and the sensor 12 are directly disposed on the workpiece 2 and are in contact with the workpiece 2. In addition, the workpiece 2 used in this embodiment is a S45C medium carbon steel plate. The size of the workpiece 2 is 1000 mm × 300 mm × 20 mm, and the surface is pickled with weak acid. After the surface rust is removed, the residual stress is measured.

Referring to FIG. 1, FIG. 2, and FIG. 3, the steps of the simple stress relief combined embodiment are described as follows:

Step 31: The spectrum analyzer 13 receives the voltage signal V from the sensor 12 and obtains the amplitude and vibration frequency of the workpiece 2 when it fluctuates inside.

Step 32: The spectrum analyzer 13 removes the self-resonance of the sensor 12.

Step 33: The spectrum analyzer 13 performs a Fast Fourier Transform (FFT) operation according to the received voltage signal V, converts the voltage signal V into a frequency domain signal, and calculates a frequency response function to obtain the frequency spectrum of the resonance wave.

Step 34: The spectrum analyzer 13 separates the main vibration wave in the frequency domain below 100 _Hz and the resonance wave in the frequency domain between 250 and 1750 _Hz for the spectrum obtained by the aforementioned frequency response function, and detects the main vibration wave, The peak value of the amplitude of the resonance wave. It is worth noting that, in the aforementioned separated resonance wave, the preferred frequency range is a resonance wave between 450-1050 _Hz .

It is worth noting that when the spectrum analyzer 13 performs a spectrum analysis, it analyzes the vibration frequency and amplitude. Referring to FIG. 4, it can be observed that the time-domain waveform diagram measured after the spectrum analyzer 13 receives the voltage signal V. After the conversion of 34, the spectrum diagram as shown in Figure 5 is obtained. From Figure 5, it can be found that the peak value in the left vibration frequency 100H _Z is the vibration frequency of the main vibration wave input by the shaker 11 and the right vibration frequency is about 800 Hz _Z. The peak value is the vibration frequency of the resonance wave inside the workpiece 2.

Step 35: The spectrum analyzer 13 obtains the vibration frequency corresponding to the maximum amplitude of the resonance wave according to the peak value of the amplitude of the resonance wave.

Step 36: The spectrum analyzer 13 uses the vibration frequency corresponding to the maximum amplitude in step 35 as the rated vibration frequency of the exciter 11.

As shown, the waveform in the frequency domain between the resonance waves between the 450-1050H _z, 5 can clearly see a change in amplitude, which corresponds to the maximum amplitude exciter (Discovering primary) vibration frequency 11 ( 0 ~ 100H _Z ), which is the rated vibration frequency applied when eliminating residual stress.

FIG 4, FIG 5 can identify, the maximum amplitude of the frequency domain interposed between the resonance wave generated 450-1050H _z, corresponds to the nominal frequency of the vibration is 47H _Z, and the maximum amplitude is the primary generated Discovering The resonance point corresponds to a vibration frequency of 50H _Z.

Step 37: The spectrum analyzer 13 also outputs an electric control signal S to control the excited vibration 11 to generate vibration at the rated vibration frequency, so that the vibration wave is continuously transmitted to the workpiece 2 and effectively eliminates most of the residue of the workpiece 2 stress.

Thus, using the same condition of the workpiece 2 as the test piece, the shaker 11 uses a rated frequency of 47H _Z as the experimental group, a frequency of 50H _Z as the first control group, and a frequency of 39H _Z as The second control group, the vibration frequency using 43H _Z was the third control group, and the vibration mode B of the Republic of China Patent No. 201235486 was used as the fourth control group.

When the vibration waves are transmitted to the respective workpieces 2 at the vibration frequencies of 47H _Z , 50H _Z , 39H _Z , and 43H _Z for 20 minutes, the resonance waves in the frequency range between 450H _{Z and} -1050H _Z can be separated and processed. Measurement of residual stress. In this embodiment, the residual stress is measured by cosα method-residual stress measurement technology (Cr target XRD).

Referring to FIG. 6, it can be clearly seen that the amplitude of the resonance wave of the first control group is 0.112 V and the residual stress elimination ratio is 36.2%; the amplitude of the resonance wave of the second control group is 0.128 V and the residual stress elimination ratio is 38.5 %; The amplitude of the resonance wave in the third control group is 0.36 V, and the residual stress elimination ratio is 42.3%; the amplitude of the resonance wave in the fourth control group is 0.62 V (not disclosed in Case No. 201235468), and the residual stress elimination ratio is 39.3 %.

The experimental group of the present invention, at the rated frequency of vibration resonance wave vibrator 47H _Z Faldan to 1.01 mV, and residual stress relief ratio reached 46.1% for the best. Obviously, the larger the amplitude of the resonance wave in the frequency range between 450H _Z -1050H _Z , the better the stress relief effect.

In addition, it is worth noting that the spectrum analyzer 13 of the present invention may not be electrically connected to the exciter 11, and step 37 is omitted, and after obtaining the rated vibration frequency, the exciter 11 is manually adjusted to use the rated The vibration frequency generates vibration. Thereby, the vibration wave can also be continuously transmitted to the workpiece 2, and most of the residual stress of the workpiece 2 can be effectively eliminated. Since those with ordinary knowledge in the art can infer the extended details based on the above description, they will not be described further.

Through the above description, the advantages of the foregoing embodiments can be summarized as follows:

1. Compared with heat treatment, the present invention can greatly reduce the waste of energy, and is not limited by the construction site, but can simplify procedures and reduce costs.

2. Since the vibration frequency used by the exciter 1 is between 1H _Z and 100H _Z , it belongs to low frequency, and the rated vibration frequency corresponding to the separated resonance wave will be lower than the resonance frequency of the resonance point, so compared with the resonance point The vibration generated by the vibration frequency is small, which can greatly reduce the damage and fatigue to the workpiece 2.

3. Furthermore, the present invention can accurately and timely find the maximum amplitude of the resonance wave through signal processing and fast Fourier analysis, and further improve the speed and accuracy of determining the rated vibration frequency without the need for manual interpretation. Quite simple, but can improve the convenience and practicality.

However, the above are only examples of the present invention. When the scope of implementation of the present invention cannot be limited by this, any simple equivalent changes and modifications made according to the scope of the patent application and the contents of the patent specification of the present invention are still Within the scope of the invention patent.

1‧‧‧ Stress Relief Device

11‧‧‧Vibrator

12‧‧‧ Sensor

13‧‧‧Spectrum Analyzer

2‧‧‧ Workpiece

31 ~ 37‧‧‧step flow

V‧‧‧Voltage signal

S‧‧‧Electrical control signal

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: FIG. 1 is a schematic diagram illustrating an embodiment of a simple stress relief method and device of the present invention; FIG. 2 is a schematic diagram It is explained that the main vibration wave and the resonance wave are separated by Fourier operation in this embodiment; FIG. 3 is a flowchart of the embodiment; FIG. 4 is a time-domain waveform diagram of the embodiment; and FIG. 5 is the embodiment And FIG. 6 is a comparison table between this example and four control groups.

Claims (9)

A simple stress relief method, using a stress relief device as a tool, the stress relief device includes an exciter that transmits a vibration wave to a workpiece at a vibration frequency between 1H _Z to 100H _Z , is connected to the workpiece and senses amplitude A sensor connected to the vibration frequency and a spectrum analyzer electrically connected to the sensor. The simple stress relief method includes the following steps: Step a: The spectrum analyzer receives a voltage signal from the sensor, The voltage signal includes the sensed amplitude and vibration frequency. Step b: The spectrum analyzer obtains the frequency spectrum of the resonance wave by performing a Fourier Transform (FFT) operation according to the amplitude and vibration frequency in the foregoing voltage signal. Step c : The spectrum analyzer separates a resonance wave in the frequency domain between 250H _Z -1750H _Z ; step d: the spectrum analyzer obtains the vibration frequency corresponding to the maximum amplitude of the resonance wave; and step e: the spectrum analyzer uses the step The vibration frequency of d is a rated vibration frequency of the shaker, so that the shaker continuously generates vibrations at the rated vibration frequency, and transmits the vibrations. Wave to the workpiece. According to the simple stress relief method described in claim 1, the spectrum analyzer is also electrically connected to the exciter, wherein the spectrum analyzer of step e also outputs an electric control signal to control the exciter at the rated vibration frequency. Generate vibration. The simple stress-relief method according to claim 2, wherein the spectrum analyzer in step b is calculated using a Fourier Transform (FFT) operation, and after calculating the frequency response function, the spectrum analysis is further performed in step c. The instrument separates the main vibration wave in the frequency domain between 0 ~ 100H _z and the resonance wave in the frequency domain between 250H _Z -1750H _Z according to the aforementioned frequency response function, and detects the peak value of the amplitude of the main vibration wave and the resonance wave. The simple stress relief method according to claim 1, further comprising step f after step a and before step b: the spectrum analyzer removes the self-resonance of the sensor. The simple stress relief method according to claim 1, wherein, in the aforementioned separated resonance wave, a preferred frequency range is a resonance wave between 450-1050 _Hz . A simple stress relief device includes: an exciter that transmits a vibration wave to a workpiece at a vibration frequency between 1H _Z and 100H _Z ; a sensor connected to the workpiece and used to sense amplitude and vibration frequency And the output includes a voltage signal of amplitude and vibration frequency; and a spectrum analyzer, which is electrically connected to the sensor, and according to the received voltage signal, performs a Four Fourier Transform (FFT) operation to obtain the resonance wave's The frequency spectrum, and the resonance wave in the frequency domain between 250H _Z -1750H _Z are separated, and the vibration frequency corresponding to the maximum amplitude of the resonance wave is obtained, and it is used as a rated vibration frequency of the shaker, so that the shaker continues Vibration is generated at the rated vibration frequency and transmitted to the workpiece. The simple stress relief device according to claim 6, wherein the spectrum analyzer is also electrically connected to the exciter, and the spectrum analyzer also outputs an electric control signal to control the induced vibration to generate vibration at the rated vibration frequency . The simple stress relief device according to claim 6, wherein the exciter and the sensor are provided on the workpiece. The simple stress relief device according to claim 6, wherein, in the aforementioned separated resonance wave, a preferred frequency range is a resonance wave between 450-1050 _Hz .