CN103278568A - A kind of ultrasonic hardness tester and testing method thereof - Google Patents

Abstract

The invention relates to the technical field of equipment and a method for measuring material hardness, in particular to an ultrasonic hardness meter and a test method thereof. The hardness testing device comprises a host terminal and a hardness testing probe, wherein the host terminal comprises a core control module consisting of an MCU (microprogrammed control Unit) processor, an internal processing circuit, a communication interface and a signal shaping unit; the hardness test probe comprises a probe shell, a vibrating rod, an emission sensing device, a receiving sensing device, an integrated circuit board and a communication joint, wherein the vibrating rod, the emission sensing device, the receiving sensing device, the integrated circuit board and the communication joint are arranged in the probe shell; and a data line is arranged between the host terminal and the hardness test probe, one end of the data line is in signal connection with the communication connector, and the other end of the data line is in signal connection with the communication interface. The vibrating rod with the resonant frequency is pressed into the tested material under the driving vibration of ultrasonic waves, the resonant frequency changes, and the hardness value of the tested material is calculated through the frequency variation and the corresponding line segment function. The testing method is convenient and quick, and can avoid errors caused by manual observation of the indentation.

Description

A kind of ultrasonic hardness tester and testing method thereof

technical field

The invention relates to the technical field of equipment and methods for measuring hardness of materials, in particular to an ultrasonic hardness tester and a testing method thereof.

Background technique

Traditional hardness testing machines, such as Brinell, Rockwell, and Vickers hardness testing machines, press a specific indenter into the surface of the material to be tested with a certain static load to produce indentations on the surface, and then mechanically or optically The method directly measures the size of the indentation to evaluate the hardness of the tested material. The indentation representing the hardness value of the material should be the entire deformation of the material when loaded, but since the hardness value is read under the condition of unloading, the measured The indentation is only the residual plastic deformation, and the elastic recovery in the deformation is neglected. On the other hand, hardness values are determined under the assumption that the indentation is a reflection of the true geometry of the indenter, whereas in reality the residual indentation does not exactly correspond to the shape of the indenter.

The measurement of the traditional Leeb hardness tester is based on the principle of incomplete elastic collision, and the hardness value is determined by the impact energy loss in the collision. Since the Leeb hardness value depends on the proportion of the elastic deformation work in the indentation of the tested material to the total deformation work, and the collision process time is extremely fast, the indentation process is extremely short, so any influence on the rebound of the impact body Speed, consumption of impact energy, and insufficient indentation will all affect the measurement, and the technical conditions in the application process are limited to a certain extent.

In addition, the measurement time of the traditional desktop hardness testing machine is relatively long, and the average measurement time is about 30 seconds each time. The efficiency is relatively low, and it is impossible to realize the quality inspection of all products on the product line. Moreover, due to the relatively large loading force of the traditional desktop hardness testing machine, the test force causes great damage to the surface of the measured material, which limits the measurement of finished products, and the desktop machine is relatively heavy, unable to work at high altitudes, and cannot measure many finished products.

Contents of the invention

The invention provides an ultrasonic hardness tester and a testing method thereof aiming at the problems in the prior art, which can measure the hardness of a material in a portable and fast manner, and effectively avoid errors caused by manual observation of indentation and indentation deformation. .

In order to solve the above technical problems, the present invention adopts the following technical solutions:

An ultrasonic hardness tester, comprising a host terminal and a hardness test probe, the host terminal includes a core control module inside, the core control module is composed of an MCU processor, an internal processing circuit, a communication interface and a signal shaping unit, and the host terminal is externally The upper surface is provided with a display and control buttons, and the display and the control buttons are respectively connected to the core control module; the hardness test probe includes a probe housing and a vibrating rod installed inside the probe housing, a transmitting induction device, a receiving induction devices, integrated circuit boards and communication connectors, the transmitting and receiving sensing devices are respectively installed on both sides of the vibrating rod and electrically connected to one end of the integrated circuit board, and the communication connectors are fixedly installed on the top of the probe housing And it is connected with the other end signal of the integrated circuit board; a data line is arranged between the host terminal and the hardness test probe, one end of the data line is connected with the communication connector of the hardness test probe, and the other end of the data line is One end is signal-connected with the communication interface of the core control module.

Wherein, the integrated circuit board is provided with a signal transmitting unit, a signal processing unit and a signal output unit, respectively realizing signal excitation, amplification processing and signal output.

Wherein, a fixing block of a vibrating rod is installed inside the probe housing, and one end of the vibrating rod is welded and fixed on the fixing block.

Wherein, the control keys include a material selection key, a confirmation key, a system menu key, a hardness conversion key, a backlight and switch integrated key, and direction keys, and the direction keys include an up key, a down key, a left key and a right key.

Wherein, the core control module also includes one or more sets of data storage connected thereto.

A kind of hardness testing method that is applied to above-mentioned ultrasonic hardness tester, described hardness testing method comprises:

Step 1: Provide multiple standard blocks with known hardness; the hardness of the standard blocks from small to large is: HV ₁ , ..., HV _n ;

Step 2: The hardness test probe performs automatic detection and when the vibrating rod resonates, the resonant frequency is measured ;

、……、

，其中

所对应的标准块的硬度为该材料的最小硬度，

所对应的标准块的硬度为该材料的最大硬度； Step 3: The vibrating rod is pressed into each standard block to be tested, and the vibrating rod resonates with each standard block respectively, and the changed resonant frequency is measured; the resonant frequency corresponding to the standard blocks with hardness ranging from small to large is

,...,

,in

The hardness of the corresponding standard block is the minimum hardness of the material,

The hardness of the corresponding standard block is the maximum hardness of the material;

，其计算公式为

=-

，……，

=

-

； Step 4: Test the variation of the resonance frequency of each standard block with an ultrasonic hardness tester

, its calculation formula is

= -

,...,

=

-

;

，HV_i-1）、（

，HV_i）的线段函数；其中，1<i＜n；并且计算出A_i和b_i的值； Step 5: Establish line segment function Y=A ₁ x+b ₁ ; ...; Y=A _n-1 x+b _n-1 ; where the function Y=A _i x+b _i means that the two ends are (

, HV _i-1 ), (

, HV _i ) line segment function; where, 1<i<n; and calculate the values of A _i and b _i ;

，并计算出谐振频率变化量

； Step 6: Take the object to be tested, and use the ultrasonic hardness tester to test the corresponding resonance frequency of the object to be tested.

, and calculate the resonant frequency variation

;

处于步骤5中的哪个线段函数的区域内；并通过相应的线段函数计算出被测物体的硬度值。 Step 7: Judge

It is in the area of which line segment function in step 5; and calculate the hardness value of the measured object through the corresponding line segment function.

。 Among them, in step 3, the resonant signal of the vibrating rod and the standard block is amplified by the signal of the integrated circuit board, and then the value is obtained after being shaped by the signal shaping unit

.

Beneficial effects of the present invention:

进行测量，测试出

；然后，将振动杆压入被测材料，振动杆与被测材料产生共振，谐振频率变为

，再测试出

，然后得出

=

-

；根据被相应的线段函数计算出硬度值。硬度测试过程在3秒钟内全部完成，然后保存数据。本发明便携快捷，测量时间快，效率高；另外，超声波硬度计的试验力很小，测量产生压痕小，通过超声波振动测试可避免人工观察压痕和压痕变形产生的误差。     The host terminal of the present invention is turned on and powered on, the MCU processor in the core control module is initialized, and the initial drive signal is sent to the integrated circuit board of the hardness test probe, so that the vibrating rod resonates, and the host terminal responds to the resonance frequency at this time

take measurements, test out

; Then, press the vibrating rod into the material under test, the vibrating rod resonates with the material under test, and the resonant frequency becomes

, and then test out

, and then get

=

-

; Calculate the hardness value according to the corresponding line segment function. The hardness testing process is all completed within 3 seconds, and then the data is saved. The invention is portable and quick, has quick measurement time and high efficiency; in addition, the test force of the ultrasonic hardness tester is very small, and the indentation produced by measurement is small, and the errors caused by manual observation of the indentation and indentation deformation can be avoided through the ultrasonic vibration test.

Description of drawings

Fig. 1 is a structural schematic diagram of an ultrasonic hardness tester of the present invention.

Fig. 2 is a schematic cross-sectional view of an ultrasonic hardness tester of the present invention.

Fig. 3 is an operation flowchart of a hardness testing method applied to ultrasonic hardness.

Reference numerals in FIGS. 1 to 3 include:

1—Host terminal 2—Hardness test probe 21—Probe housing

22—vibration rod 23—transmitting induction device 24—receiving induction device

25—integrated circuit board 26—communication connector 27—fixed block

31—MCU processor 32—Communication interface 4—Display

5—Control button 6—Data cable.

Detailed ways

In order to facilitate the understanding of those skilled in the art, the present invention will be further described below in conjunction with the embodiments and accompanying drawings, and the contents mentioned in the embodiments are not intended to limit the present invention. Referring to Fig. 1 to Fig. 3, the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Fig. 2 and Fig. 3, an ultrasonic hardness tester provided by the present invention includes a host terminal 1 and a hardness test probe 2, and the host terminal 1 includes a core control module inside, and the core control module is composed of an MCU processor 31, An internal processing circuit (not shown in the drawings), a communication interface 32 and a signal shaping unit (not shown in the drawings), the host terminal 1 is provided with a display 4 and control buttons 5 on the outer upper surface, the The display 4 and the control buttons 5 are respectively connected to the core control module; the hardness test probe 2 includes a probe housing 21 and a vibrating rod 22 installed inside the probe housing 21, a transmitting induction device 23, a receiving induction device 24, an integrated The circuit board 25 and the communication connector 26, the transmitting induction device 23 and the receiving induction device 24 are respectively installed on both sides of the vibrating rod 22 and are electrically connected to one end of the integrated circuit board 25, and the communication connector 26 is fixedly installed on the probe The top of the housing 21 is connected to the other end of the integrated circuit board 25 for signal connection; a data line 6 is arranged between the host terminal 1 and the hardness test probe 2, and one end of the data line 6 is connected to the hardness test probe 2. The communication connector 26 is connected with signals, and the other end of the data line 6 is connected with the communication interface 32 of the core control module 3 for signals.

The transmitting induction device 23 installed on the vibrating rod 22 is responsible for sending ultrasonic signals to make the vibrating rod 22 resonate, and the receiving inductive device 24 is responsible for receiving the vibration signal of the vibrating rod 22 . In the actual test, the integrated circuit board 25 of the hardness test probe 2 transmits an electric signal to drive the transmitting induction device 23 to cause the vibrating rod 22 to resonate, and the receiving inductive device 24 receives the ultrasonic wave from the vibrating rod 22 and feeds back the resonance signal to the integrated circuit board 25 , the integrated circuit board 25 processes the resonance signal, and then outputs it to the host terminal 1 through the data line 6 .

The resonance signal of the hardness test probe 2 is input to the communication interface 32 through the data line, and after being processed by the internal processing circuit and the signal shaping unit on the core control module, it is input to the MCU processor 31, and the internal program of the MCU processor 31 performs the resonance signal processing. Counting process, the calculated hardness value is displayed on the display 4.

Wherein, the integrated circuit board 25 is provided with a signal transmitting unit, a signal processing unit and a signal output unit, respectively realizing signal excitation, amplification processing and signal output. The output signals induced by the transmitting induction device 23 and the receiving induction device 24 inside the probe housing 21 are relatively weak, and the integrated circuit board 25 excites, amplifies and outputs the output signal, which can effectively improve the signal stability and achieve the guarantee. for measurement accuracy and stability purposes. The present invention adopts two sets of inductive devices (transmitting inductive device 23 and receiving inductive device 24), removes the traditional magnetic excitation coil, and makes the signal more stable; since the signal is processed by the integrated control circuit board 25 and then output, the anti-interference is strengthened Ability to further improve stability and applicability.

Wherein, a fixing block 27 of the vibrating rod 22 is installed inside the probe housing 21 , and one end of the vibrating rod 22 is fixedly welded on the fixing block 27 . The vibrating rod 22 is fixedly connected with the fixed block 27 as a whole, so that the guide will not deviate; the vibrating rod 22 does not shake during the pressing process, effectively ensuring the pressing angle and accuracy.

As shown in Figure 1, the control buttons 5 include a material selection key, a confirmation key, a system menu key, a hardness conversion key, a backlight and a switch integrated key, and direction keys, and the direction keys include an up key, a down key, a left key and right click. The switch key can realize switch and backlight control. Through the system menu key, you can enter the system to set various parameters, and switch with the left key, up key, down key and right key, switch the hardness scale through the hardness conversion key, and select the material through the key to select the material.

Wherein, the core control module also includes one or more sets of data memory (not marked in the drawings) connected thereto. The MCU processor 31 performs different processing on the measurement data according to the user’s setting of the system, and then saves the processing results in the data memory. After the hardness test is completed, the measurement data is exported to the computer through the communication interface 32, and then synthesized. processing and analysis.

A kind of hardness testing method that is applied to above-mentioned ultrasonic hardness tester, described hardness testing method comprises:

Step 1: Provide multiple standard blocks with known hardness; the hardness of the standard blocks from small to large is: HV ₁ , ..., HV _n ;

； Step 2: The hardness test probe performs automatic detection and when the vibrating rod resonates, the resonant frequency is measured

;

、……、

，其中

所对应的标准块的硬度为该材料的最小硬度，所对应的标准块的硬度为该材料的最大硬度； Step 3: The vibrating rod is pressed into each standard block to be tested, and the vibrating rod resonates with each standard block respectively, and the changed resonant frequency is measured; the resonant frequency corresponding to the standard blocks with hardness ranging from small to large is

,...,

,in

The hardness of the corresponding standard block is the minimum hardness of the material, The hardness of the corresponding standard block is the maximum hardness of the material;

，其计算公式为

=

-

，……，

=

-； Step 4: Test the variation of the resonance frequency of each standard block with an ultrasonic hardness tester

, its calculation formula is

=

-

,...,

=

- ;

，HV_i-1）、（

，HV_i）的线段函数；其中，1<i＜n；并且计算出A_i和b_i的值； Step 5: Establish line segment function Y=A ₁ x+b ₁ ; ...; Y=A _n-1 x+b _n-1 ; where the function Y=A _i x+b _i means that the two ends are (

, HV _i-1 ), (

, HV _i ) line segment function; where, 1<i<n; and calculate the values of A _i and b _i ;

，并计算出谐振频率变化量

；其中，被测物的材料与标准块的材料一样； Step 6: Take the object to be tested, and use the ultrasonic hardness tester to test the corresponding resonance frequency of the object to be tested.

, and calculate the resonant frequency variation

; Among them, the material of the measured object is the same as that of the standard block;

处于步骤5中的哪个线段函数的区域内；并通过相应的线段函数计算出被测物体的硬度值。 Step 7: Judge

It is in the area of which line segment function in step 5; and calculate the hardness value of the measured object through the corresponding line segment function.

。在步骤4中，当计算出

后，MCU处理器对计算结果

进行线性补偿。 Among them, in step 3, the resonant signal of the vibrating rod and the standard block is amplified by the signal of the integrated circuit board, and then the value is obtained after being shaped by the signal shaping unit

. In step 4, when the calculated

After, the MCU processor calculates the result

Perform linear compensation.

，然后把振动杆22压入被测材料，这时候振动杆22的震动固定频率

会根据被测材料的不同硬度发生变化，通过这变化的频率变化量去算出被测材料的硬度值。 The principle of the measuring method of the present invention is to make the vibrating bar 22 vibrate at a fixed frequency with ultrasonic waves

, and then press the vibrating rod 22 into the material to be tested, at this time the vibration of the vibrating rod 22 has a fixed frequency

It will change according to the different hardness of the tested material, and calculate the hardness value of the tested material through the frequency change of this change.

For example: we take two standard blocks, the hardness of which is 20HRC and 30HRC respectively; use the ultrasonic hardness tester to measure: the frequency △f corresponding to the hardness of 20HRC is 1KHZ, and the frequency △f corresponding to the hardness of 30HRC is 2KHZ. According to the line segment function Y=A ₁ x+b ₁ , substitute the above two hardness values to obtain the equation Y=Ax+b; get A=0.001, b=10; that is, Y=0.001x+10.

Then use the ultrasonic hardness tester to punch the standard block of 40HRC. If the obtained frequency △f is 3KHZ, substitute the data of the standard block of 30HRC and 40HRC into the values of A2 and b2 to obtain the function Y2= between 30HRC and 40HRC A2x+b2;

后，判断

落在哪个区间，然后代入计算得出硬度值。 Then, divide N segments in the hardness measurement range, draw N equations end-to-end intersection, test the measured material by the ultrasonic hardness tester provided by the present invention, when the test obtains

After, judge

Which interval it falls in, and then substitute it into the calculation to get the hardness value.

应该在一个重复的误差范围内，当测试出来的值在误差范围内，该产品符合生产硬度要求；如果测试出来的

值不在误差范围内，则说明该产品不符合生产硬度要求，通过这样去判别不良品。 The test method of the present invention is a comparison measurement method, which is often used to detect the hardness of products in batches, because the hardness requirements of a batch of products must be within a range of error, so the results tested by this ultrasonic hardness tester

should be within a repeatable error range when the test comes out The value is within the error range, the product meets the production hardness requirements; if the tested

If the value is not within the error range, it means that the product does not meet the production hardness requirements, and the defective products are judged in this way.

的计算公式也可以为：=（Eeff，A），式中：

代表频率变化量，Eeff代表弹性模量，A代表压痕面积。由这个公式可知，

与Eeff、A之间存在可计算的比例关系（某种函数关系）。而从压痕与形变的角度来看，硬度值HV与压力F、压痕面积A也存在可计算的比例关系，也就是传统的计算方法是：HV=F/A； In addition, the frequency variation

The calculation formula of can also be: = (Eeff, A), where:

Represents the frequency change, Eeff represents the elastic modulus, and A represents the indentation area. From this formula, it can be known that

There is a calculable proportional relationship (some kind of functional relationship) between Eeff and A. From the perspective of indentation and deformation, there is also a calculable proportional relationship between the hardness value HV, the pressure F, and the indentation area A, that is, the traditional calculation method is: HV=F/A;

与Eeff来表示A而不用去测量压痕直径。由于力值F可以事先设定（振动杆压紧到被材料表面，靠的就是施力弹簧，而弹簧的压紧力是可以事先设定的，这就是超声波探头有不同型号的缘故，其型号的不同，就是取决于弹簧压紧力，簧压紧力从10N~98N不等），那么硬度值的计算公式可以转化成：HV=F/（

，Eeff）。不用费心去观察压痕了，也避免压痕边缘不清晰和形变所带来的误差了。由于不同材料的弹性模量会有差异，而且

为变化量，得先把弹性模量Eeff测量出来，否则无法应用上述的计算公式，除非事先知道被测材料的弹性模量Eeff。 The indentation produced by the traditional Vickers hardness machine is very small, and the judgment of the edge of the indentation is observed by humans, and mistakes are inevitable. The indentation produced by the vibrating rod 22 of the present invention is even smaller, but the frequency can be accurately obtained by calculation of the circuit; if we know the elastic modulus of a certain material and have measured the frequency, we can use the conversion relationship

Express A with Eeff instead of measuring the indentation diameter. Since the force value F can be set in advance (the vibrating rod is pressed to the surface of the material, it relies on the force spring, and the pressing force of the spring can be set in advance, which is why there are different types of ultrasonic probes. The difference is that it depends on the spring compression force, which ranges from 10N to 98N), then the calculation formula of the hardness value can be converted into: HV=F/(

, Eeff). You don't have to bother to observe the indentation, and you can avoid errors caused by unclear edges and deformation of the indentation. Since the modulus of elasticity of different materials will be different, and

In order to change the amount, the elastic modulus Eeff must be measured first, otherwise the above calculation formula cannot be applied, unless the elastic modulus Eeff of the measured material is known in advance.

，Eeff）。首先用机器去打硬度标准块得出HV，然后用超声波去打标准块得到

，用代入函数算出HV_测量值。然后确定一个比例关系C=HV/HV_测量值，即HV1=(A₁

+b)*C 。 When using the present invention, when the elastic modulus Eeff of the measured material is an unknown number, a sample piece is made with the tested material in advance, and the hardness value HV is first measured with a desktop computer in the prior art, and expressed as HV=F/ ( , Eeff). Use the ultrasonic hardness tester of the present invention to test the hardness value HV1 of the tested material of the same kind of different hardness values, expressed as HV1=F/(

, Eeff). First use a machine to punch the hardness standard block to get HV, and then use ultrasonic to punch the standard block to get

,use Substitute the function to calculate the HV _measurement . Then determine a proportional relationship C=HV/HV _{measured value} , namely HV1=(A ₁

+b)*C .

The above content is only a preferred embodiment of the present invention. For those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and application scope. limits.

Claims (7)

1. OnePlant the ultrasound wave sclerometer, it is characterized in that: comprise host terminal and hardness test probe, described host terminal inside comprises kernel control module, this kernel control module is made up of MCU processor, inter-process circuit, communication interface and signal reshape unit, described host terminal external upper is provided with display and control button, and described display, control button are connected with kernel control module respectively; Described hardness test probe comprises probing shell and is installed on the vibrating arm of probing shell inside, emission sensing device, reception sensing device, surface-mounted integrated circuit and communication connector, described emission sensing device and reception sensing device correspondence respectively are installed on the both sides of vibrating arm and all are electrically connected with an end of surface-mounted integrated circuit, and described communication connector is fixedly installed in the top of probing shell and is connected with the other end signal of surface-mounted integrated circuit; Be provided with data line between described host terminal and the hardness test probe, an end of described data line is connected with the communication connector signal of described hardness test probe, and the other end of described data line is connected with the communication interface signal of described kernel control module.

2. according to claim 1 OnePlant the ultrasound wave sclerometer, it is characterized in that: described surface-mounted integrated circuit is provided with signal transmitter unit, signal processing unit and signal output unit, realizes signal excitation respectively, amplifies and handle and signal output.

3. according to claim 1 OnePlant the ultrasound wave sclerometer, it is characterized in that: described probing shell inside also is equipped with the fixed block of vibrating arm, and an end of described vibrating arm is fixedly welded on the described fixed block.

4. according to claim 1 OneKind of ultrasound wave sclerometer is characterized in that: described control button comprises the material options button, determines key, System menu key, hardness shift key, backlight and switch one key and directionkeys, and described directionkeys comprises key, time key, left button and right button.

5. according to claim 1 OnePlant the ultrasound wave sclerometer, it is characterized in that: described kernel control module also comprises the data-carrier store that one or more groups is attached thereto.

6. be applied to the scleroscopic a kind of hardness measuring method of above-mentioned ultrasound wave, it is characterized in that: described hardness measuring method comprises:

Step 1: the calibrated bolck that a plurality of known hardness are provided; The hardness of calibrated bolck is followed successively by from small to large: HV ₁..., HV _n

Step 2: the hardness test probe detects automatically and when vibrating arm generation resonance, records resonance frequency

Step 3: vibrating arm is pressed into each tested calibrated bolck respectively, vibrating arm respectively with each calibrated bolck generation resonance, record the resonance frequency after the variation; The corresponding resonance frequency of hardness calibrated bolck from small to large is

...,

, wherein

The hardness of corresponding calibrated bolck is the minimum hardness of this material,

The hardness of corresponding calibrated bolck is the highest hardness of this material;

Step 4: the resonance frequency variable quantity that tests out each calibrated bolck by the ultrasound wave sclerometer

, its computing formula is

=

-

...,

=

-

Step 5: set up line segment Function Y=A ₁X+b ₁ Y=A _N-1X+b _N-1Function Y=A wherein _iX+b _i, the expression two-end-point be (

, HV _I-1), (

, HV _i) the line segment function; Wherein, 1＜i＜n; And calculate A _iAnd b _iValue;

Step 6: get measured object, test out the corresponding resonance frequency of measured object by the ultrasound wave sclerometer and be

, and calculate the resonance frequency variable quantity

Step 7: judge

Which be in the zone of the line segment function in the step 5; And go out the hardness number of testee by corresponding line segment function calculation.

7. hardness measuring method according to claim 6 is characterized in that: in step 3, the signal of vibrating arm and calibrated bolck generation resonance amplifies through the integrated circuit partitioned signal, pass through the shaping of signal reshape unit again after, just draw numerical value

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