CN113639903A - Stress detection method in FDM printing process - Google Patents

Abstract

The invention provides a stress detection method in an FDM printing process, comprising the following steps: step 1, making a Solidworks part model to be formed, selecting an area to be measured, and leaving an empty slot in the area to be measured to place a sensor; step 2, when the FDM printer is used Print to the layer where the empty slot is located and pause the printing process; step 3, adjust the orientation of the empty slot in the model to be measured, and then adjust the direction of the strain gauge to measure the stress in directions such as X, Y, 45°; step 4, pass the bridge box Connect to the strain gauge, connect the strain gauge to the acquisition card, and the acquisition card stores the voltage signal transmitted by the strain gauge to the computer, ready to collect; Step 5, the strain gauge starts to record the voltage output by the strain gauge; the FDM printer continues to print parts; Step 6, According to the actual printing and cooling time of the part, the zero drift within 30 minutes is measured, and the zero drift is removed by the method of signal processing; the invention solves the problem that other strain detection methods cannot detect the internal stress of FDM parts and are expensive.

Description

A method of stress detection in FDM printing process

technical field

The invention relates to the technical field of stress detection, and relates to a stress detection method in an FDM printing process.

Background technique

Fused deposition modeling technology is referred to as FDM technology. FDM is widely used due to its wide range of molding materials, low cost, and low equipment operation and maintenance costs. However, since most of the materials used in this technology are high molecular organic synthetic plastics, the final molding parts will be. There are dimensional shrinkage, warpage deformation, etc. that affect the molding accuracy. The distribution gradient of the temperature field during the forming process will cause thermal stress and deformation inside the part, which will cause the change of the external dimension of the part and seriously affect the forming accuracy of the part. The low molding quality of the parts seriously limits the popularization and application of fused deposition rapid prototyping technology in the market. This makes its application areas mainly focus on the production of test models and functional prototypes in the R&D test link. Therefore, it is of great significance to study the distribution of temperature field and stress field in the FDM molding process to reveal the law and mechanism of dimensional shrinkage of parts, and to promote the application of FDM technology.

The resistance strain gauge measurement method is the most traditional method of measuring strain and is widely used. The measurement principle is to paste the strain gauge on the deformation place. When the structure is strained, the resistance value of the strain gauge will also change. The strain gauge can convert the resistance change signal into a voltage or current signal, and the strain of the structure can be obtained. value. The strain gauge measurement method has the advantages of high precision and small size. The strain gauge can be embedded in the specimen, and according to the relationship between the resistivity of the resistance wire and the deformation of the resistance wire, the mechanical parameters can be converted into electrical parameters, and then the electrical parameters can be converted into the strain value of the specimen, so that the specimen can be measured. The distributed point strain provides the possibility to study the internal stress change of FDM. Moreover, the strain gauge measuring equipment is cheap, which is convenient to be widely used in the stress measurement of FDM specimens.

The purpose of the present invention is to develop a test system for the temperature field and stress field in the FDM forming process. A method of stress testing in FDM molding process is proposed.

SUMMARY OF THE INVENTION

The invention aims to invent a method for measuring the internal dynamic stress of an FDM part in the FDM forming process, so as to solve the problem that other strain detection methods cannot detect the internal stress of the FDM part and are expensive.

A method for detecting stress in an FDM printing process disclosed in the present invention comprises the following steps:

Step 1. Make the Solidworks part model to be formed as part 1, select the area to be measured, and leave an empty slot in the area to be measured to place the sensor; the size of the empty slot is the same as that of the strain gauge, and the strain gauge model is BA-120-3AA The strain gauge includes: working strain gauge R ₁ , compensation strain gauge R ₂ , compensation strain gauge R ₃ , compensation strain gauge R ₄ ;

Step 2. Use the FDM printer to load part 1, set the printing parameters, start printing, and pause the printing process when the FDM printer prints to the layer where position 2 is located;

Step 3. Grind the bottom of the strain gauge, use 502 glue, paste and fix the working strain gauge R ₁ on the area to be measured in the empty groove, adjust the orientation of the empty groove in the area to be measured in the model, and then adjust the direction of the strain gauge to measure X, Y , 45° and other directional stress;

Step 4. The working strain gauge R ₁ and the compensation strain gauge R ₂ , the compensation strain gauge R ₃ , and the compensation strain gauge R ₄ form a full bridge, which will be connected to the strain gauge through the bridge box, and the strain gauge will be connected to the acquisition card. Store the voltage signal transmitted by the strain gauge to the computer, ready to collect;

Step 5. Fix the compensation strain gauges R ₂ , R ₃ and R ₄ on the programmable heating platform 3, set the temperature of the programmable heating platform 3 to 25°C; level the strain gauge, set the sampling frequency of the acquisition card to 500Hz, The strain gauge starts to record the voltage output by the strain gauge; the FDM printer continues to print the part; record the strain gauge voltage V _ε = f(i), where i is the number of samples collected;

Step 6. The strain gauge will produce zero drift during the long-term stress measurement, and the zero drift will affect the accuracy of the measured stress. By using the same conditions as the actual measurement, according to the actual printing and cooling time of the part, measure the zero drift within 30 minutes. Use signal processing method to remove zero drift;

Step 7. During the FDM printing process, the area to be measured will undergo a strong temperature change, and the strain gauge will show different resistances at different temperatures, so it is necessary to study the temperature characteristics of the strain gauge; therefore, by using the same conditions as the actual measurement, Measure the voltage change of the strain gauge under the same temperature change in the FDM process, and use the signal processing method to remove the temperature drift according to the temperature drift characteristics of the strain gauge;

Step 8. Strain and stress calculation;

(1) Stress calculation method, let the stress measurement voltage after removing zero drift and temperature drift be _VL ;

Then, V _L =V _ε -Y _l -V ₂ ;

In the above formula, V _ε is the voltage of the strain gauge in the printing process, Y _l is the zero point drift voltage, and V ₂ is the temperature drift voltage;

The strain ε is:

Stress, F=E*ε; where E is the elastic modulus of the printing material;

(2) Write strain and stress calculation software; in the denoising part, Gaussian denoising, median filtering, mean filtering, wavelet denoising, and EMD model decomposition methods are used to remove noise according to the characteristics of the temperature stress data measured in the FDM printing process; The stress calculation part includes zero-drift filtering, temperature-drift filtering, temperature, strain, and stress calculations; and the functions of brush, data scaling, and clock are added to facilitate the processing of the details of the data.

Preferably, the step of removing zero drift in the step 6 is:

(1) Hardware connection, the working strain gauge R ₁ , compensation strain gauge R ₂ , compensation strain gauge R ₃ , compensation strain gauge R ₄ form a full bridge connection, grind the working strain gauge R ₁ , compensation strain gauge R ₂ , compensation strain gauge At the bottom of the sheet R ₃ and the compensation strain gauge R ₄ , stick the 4 strain gauges on the programmable heating platform 3 , set the temperature of the heating platform to 25°C, collect the working strain gauge R ₁ , the compensation strain gauge R ₂ , and the compensation strain Sheet R ₃ , compensation strain gauge R ₄ zero drift;

为样本均值：(2) Data preprocessing, strain gauge drift is divided into two types, one is horizontal zero point drift, the other is slope zero point drift; in the process of strain sampling, set the total strain sampling time as T, the number of samples as N, and the collected The signals are y ₁ -y _n ,

is the sample mean:

其中i＝1,2,···,N

where i=1,2,...,N

σ _y is the sample variance:

时为水平零点漂移，

时为斜率零点漂移；when

is the horizontal zero drift,

is the zero drift of the slope;

(2.1) remove the horizontal zero drift, let the voltage signal after removing the zero drift be Y _i ;

Then the zero drift voltage is:

Y _i =y(i)-Y _l ;

(2.2) Remove slope zero drift:

为第一均值点，

为第二均值点；N为样本数量；T为采样总时长；in

is the first mean point,

is the second mean point; N is the number of samples; T is the total sampling time;

其中

in

其中

in

then the slope of the sample data

Then the zero drift voltage is: Y _l =(k*t)

Signal Yi after removing slope zero _drift :

Y _i =y(i)-Y _l , where i=1,2,...,N.

Preferably, the step of removing the temperature drift in the seventh step is:

(1) Temperature test in the printing process, the FDM printer loads the second part 5, and there is an empty groove in the area to be measured, the temperature measurement area is the same as the measurement position of the strain detection, and the empty groove is the same size as the temperature sensor PT100;

Slice and print the second part 5, when the FDM printer prints to the layer where position 2 is located, the printing process is suspended; the temperature sensor PT100 is glued and fixed in the empty slot, the temperature sensor model is PT100; the temperature sensor is connected to the temperature transmitter The temperature transmitter model is ASC605-V2.0, and the acquisition card is used to record and record the voltage change of the temperature sensor during the printing process of the FDM printer;

(2) The temperature calculation of the area to be measured in the printing process; the temperature transmitter records the voltage change of the temperature sensor as V ₁ ;

V ₁ =f(i), where i=1,2,...,N.

Then the temperature change of the test point during the printing process is T ₁ ;

T ₁ =20*V ₁ ;

(3) To determine the temperature drift, the bridge connection method of the strain gauge adopts full bridge connection, input the measured temperature change T1 _of the FDM printing process into the programmable heating platform 3, and determine the temperature of the programmable heating platform 4 at 25 °C unchanged. . Connect the working strain gauge R ₁ , the compensation strain gauge R ₂ , the compensation strain gauge R ₃ , and the compensation strain gauge R ₄ to the full bridge circuit and connect the bridge to the strain gauge through the bridge box, connect the strain gauge to the acquisition card, and record through the acquisition card Under the environment of temperature change T1 in the FDM printing process, the working strain gauge R ₁ compensates the voltage change of the strain gauge R ₂ , the compensation strain gauge R ₃ , and the compensation strain gauge R ₄ at _an ambient temperature of 25°C; records the temperature drift voltage of the strain gauge V ₂ =f(i); where i=1,2,...,N. .

The beneficial effects of the present invention are as follows: the present invention aims to invent a method for measuring the internal dynamic stress of an FDM part during the FDM forming process, so as to solve the problem that other strain detection methods cannot detect the internal stress of the FDM part and are expensive.

Description of drawings

In order to clearly illustrate the existing technical solutions or embodiments in the stress testing process of the present invention, the accompanying drawings to be used will be briefly described below, and the drawings described below are only some embodiments of the present invention.

Accompanying drawing 1 is the FDM part stress detection method of the present invention;

Accompanying drawing 2 is the strain gauge bridge connection method of the present invention;

Accompanying drawing 3 is the zero drift filtering method of the present invention;

Accompanying drawing 4 is the temperature detection method of the present invention;

Accompanying drawing 5 is the temperature drift filtering method of the present invention;

Accompanying drawing 6 is the strain and stress calculation software of the present invention;

Fig. 7 is stress detection embodiment 1 of the present invention;

Fig. 8 is the temperature detection embodiment 2 of the present invention.

Detailed ways

Various embodiments of the present invention will be disclosed in the drawings below. For the sake of clarity, many physical details will be described together in the following description. It should be understood, however, that these physical details should not be used to limit the invention. That is, in some embodiments of the present invention, these physical details are unnecessary. In addition, for the purpose of simplifying the drawings, some well-known structures and components will be shown in a simple schematic manner in the drawings.

In addition, descriptions such as “first”, “second”, etc. in the present invention are only for the purpose of description, and do not refer to the meaning of order or sequence, nor are they used to limit the present invention. The components or operations are described by the same technical terms, and should not be construed as indicating or implying their relative importance or implying the quantity of the indicated technical features. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In addition, the technical solutions between the various embodiments can be combined with each other, but must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of such technical solutions does not exist. , is not within the scope of protection required by the present invention.

Stress detection method. Due to the complex temperature changes in the manufacturing process of the fused deposition modeling method, complex changes in internal stress are caused. Therefore, the present invention develops a method for measuring the internal stress of the FDM manufacturing process because of the problems of deformation and insufficient strength of the FDM manufacturing parts. Its measurement structure is shown in Figure 1.

(1) Make the Solidworks part model to be formed as part 1, select the area to be measured, and leave an empty slot in the area to be measured to place the strain sensor. The size of the empty slot is the same as the size of the strain gauge.

(2) Use the FDM printer to load part 1, set the printing material, printing temperature, printing layer thickness, printing speed, printing path, and start printing. When the FDM printer prints to the layer where position 2 is located, the printing process is suspended.

(3) Grind the bottom of the working strain gauge R ₁ , and use 502 glue to stick and fix the working strain gauge R ₁ to the area to be measured at the empty groove. Let stand for 5 minutes for the glue to set. The orientation of the cavity in the area to be measured can be adjusted in the model, and then the direction of the strain gauge can be adjusted to measure the stress in directions such as X, Y, and 45°.

(4) The working strain gauge R ₁ and the compensation strain gauges R ₂ , R ₃ , R ₄ form a full bridge, as shown in Figure 2. The bridge is connected to the strain gauge through the bridge box, and the strain gauge is connected to the acquisition card, and the acquisition card stores the voltage signal transmitted by the strain gauge to the computer. Turn on the strain gauge and collect the internal strain of the part.

(5) Fix the R ₂ , R ₃ , and R ₄ compensating sheets on the second programmable heating platform 4 , and set the temperature of the second programmable heating platform 4 to 25°C. Level the strain gauge, set the sampling frequency of the acquisition card to 500 Hz, and start recording. The FDM printer continues printing. Record the strain gauge voltage V _ε = f(i), where i = 1, 2, . . . , N. N is the number of samples collected.

2. Remove zero drift. During the long-term stress measurement of the strain gauge, zero-point drift will occur, and the zero-point drift will affect the accuracy of the measured stress. Therefore, the present invention measures the zero point drift within a certain time by using the same conditions as the actual measurement, and its measurement structure is shown in Figure 3 . And according to the characteristics of zero drift, the method of signal processing is used to remove the zero drift.

(1) Hardware connection. As shown in Figure 3, the working strain gauge R ₁ , the compensation strain gauge R ₂ , the compensation strain gauge R ₃ , and the compensation strain gauge R ₄ are formed into a full bridge connection, the bottom of the strain gauge is polished, and the 4 strain gauges are pasted and fixed on the programmable heating platform. 3, set the temperature of the programmable heating platform 3 to 25°C. Connect the bridge to the strain gauge through the bridge box, connect the strain gauge to the acquisition card, and the acquisition card stores the zero-drift voltage of the strain gauge to the computer.

为样本均值：(2) Data preprocessing. There are two types of strain gage drift, one is horizontal zero drift and the other is slope zero drift. In the process of strain sampling, set the total duration of strain sampling as T, the number of samples as N, and the collected signals as y ₁ -y _n ,

is the sample mean:

其中i＝1,2,···,N

where i=1,2,...,N

σ _y is the sample variance:

时为水平零点漂移，

时为斜率零点漂移。when

is the horizontal zero drift,

is the zero drift of the slope.

(3) remove horizontal zero drift, let the signal after removing zero drift be Y _i ;

Then the zero drift voltage is:

Y _i =y(i)-Y _l ;

(4) Remove slope zero drift:

in,

其中

in

其中

in

then the slope of the sample data

Then the zero drift voltage is: Y _l =(k*t)

Signal Yi after removing slope zero _drift :

Y _i =y(i)-Y _l , where i=1,2,...,N;

3. Remove temperature drift. During the FDM printing process, the area to be tested will undergo strong temperature changes, and the strain gauge will show different resistances at different temperatures, so it is necessary to study the temperature characteristics of the strain gauge. Therefore, the present invention measures the voltage change of the strain gauge under the same temperature change in the FDM process by using the same conditions as the actual measurement, and its measurement structure is shown in Figure 4 . And according to the temperature drift characteristics of the strain gauge, the method of signal processing is used to remove the temperature drift.

(1) Temperature test during printing. As shown in Figure 4, the FDM machine loads the second part 5, and there is an empty slot in the area to be measured. The shape of part 1 and the second part 5 is the same, only the size of the empty slot in the area to be measured is different. The position to be measured for strain detection is the same, and the empty slot is the same size as the temperature sensor PT100.

The second part 5 is sliced and printed, and the printing process is suspended when the FDM printer prints to the layer where position 2 is located. Use glue to fix the temperature sensor PT100 in the empty slot, the temperature sensor model is PT100; connect the temperature sensor to the temperature transmitter, the temperature transmitter model is ASC605-V2.0, use the acquisition card to record, record the FDM printing process The voltage change of the temperature sensor in the middle.

(2) The temperature calculation of the area to be measured during the printing process. Note the temperature sensor voltage change as V ₁ .

V ₁ =f(i), where i=1,2,...,N.

Then the temperature change of the test point during the printing process is T ₁ ;

T ₁ =20*V ₁ ;

(3) Determine the temperature drift. As shown in Figure 5, the bridge connection method of the strain gauge adopts a full bridge connection, in which R ₁ is a working piece, which is pasted and fixed on the programmable heating platform 3. R ₂ , R ₃ , and R ₄ are compensation sheets, which are pasted and fixed on the second programmable heating platform 4 . The measured temperature change T1 _of the FDM printing process is input into the programmable heating platform 3, and the temperature of the second programmable heating platform 4 is determined to be constant at 25°C. Connect the working strain gauge R ₁ , compensation strain gauge R2 , compensation strain gauge R3 , compensation strain gauge R4 to the full bridge circuit and connect the bridge to the strain gauge through the bridge box, connect the strain gauge to the acquisition card, and record the work of R ₁ through the acquisition card Under the temperature change T1 environment _of the FDM printing process, the voltage changes _of the working strain gauge R1, the compensation strain gauge R2, the compensation strain gauge R3, and the compensation strain gauge R4 under the environment of 25 °C. Record the strain gauge temperature drift voltage V ₂ =f(i). where i=1,2,...,N.

Strain and stress calculations.

(1) Stress calculation method. Let the stress measurement voltage after removing zero drift and temperature drift be _VL ;

Then, V _L =V _ε -Y _l -V ₂ ;

then, strain,

Stress, F=E*ε. where E is the elastic modulus of the printed material

(2) Write the strain and stress calculation software as shown in Figure 6. In the denoising part, Gaussian denoising, median filtering, mean filtering, wavelet denoising, EMD model decomposition and other methods are used to remove noise according to the characteristics of temperature stress data measured in the FDM printing process. The stress calculation part includes zero drift filtering, temperature drift filtering, temperature, strain, and stress calculations. And added brush, data scaling, clock and other functions to facilitate the processing of the details of the data.

Example 1: As shown in Figure 7, the present invention adopts the strain sensor model of BA-120-3AA strain gauge, the strain gauge model of YF-3 model, the FDM machine model of Ultimaker2 ⁺ , the printing material is set to PLA, and the printing temperature is 210 ℃, the printing layer thickness is 0.6mm, the printing speed is 20mm/s, and the printing path is a zigzag shape, forming a 30*30*5mm cuboid part 1, and measuring its Y-direction stress. The test position is 1.8mm in height at the center of the model.

Example 2: As shown in Figure 8, the present invention adopts the temperature sensor model of PT100 temperature sensor, the temperature transmitter model of ASC605-V2.0, the FDM machine model of Ultimaker2 ⁺ , the printing material is set to PLA, and the printing temperature is 210°C , the printing layer thickness is 0.6mm, the printing speed is 60mm/s, the printing path is a zigzag shape, and the second part 5 of a cuboid of 30*30*5mm is formed and manufactured, and the temperature at the stress measuring point is measured. The test position is 1.8mm in height at the center of the model.

The above descriptions are merely embodiments of the present invention, and are not intended to limit the present invention. Various modifications and variations of the present invention are possible for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims (3)

1. a FDM printing process stress detection method, is characterized in that, comprises the steps: Step 1. Make the Solidworks part model to be formed as part (1), select the area to be measured, and leave an empty slot in the area to be measured to place the sensor; the size of the empty slot is the same as that of the strain gauge, and the strain gauge model is BA-120 -3AA, the strain gauge includes: working strain gauge R ₁ , compensation strain gauge R ₂ , compensation strain gauge R ₃ , compensation strain gauge R ₄ ; Step 2, use the FDM printer to load the part (1), set the printing parameters, start printing, and pause the printing process when the FDM printer prints to the layer where the position (2) is located; Step 3. Grind the bottom of the strain gauge, use 502 glue, paste and fix the working strain gauge R ₁ on the area to be measured in the empty groove, adjust the orientation of the empty groove in the area to be measured in the model, and then adjust the direction of the strain gauge to measure X, Y , 45° direction stress; Step 4. The working strain gauge R ₁ and the compensation strain gauge R ₂ , the compensation strain gauge R ₃ , and the compensation strain gauge R ₄ form a full bridge, and are connected to the strain gauge through the bridge box, and the strain gauge is connected to the acquisition card. The voltage signal transmitted by the strain gauge is stored in the computer, ready to be collected; Step 5. Fix the compensation strain gauges R ₂ , R ₃ , and R ₄ on the programmable heating platform (3), set the temperature of the programmable heating platform (3) to 25°C; level the strain gauge, and set the acquisition card for sampling When the frequency is 500 Hz, the strain gauge starts to record the voltage output by the strain gauge; the FDM printer continues to print the part (1); record the strain gauge voltage V _ε = f(i), where i is the number of samples collected; Step 6. The zero point drift of the strain gauge will occur during the long-term stress measurement process, and the zero point drift will affect the accuracy of the measured stress. By using the same conditions as the actual measurement, according to the actual printing and cooling time of the part (1), measure the stress within 30 minutes. Zero drift, using signal processing method to remove zero drift; Step 7. During the FDM printing process, the area to be measured will undergo a strong temperature change, and the strain gauge will show different resistances at different temperatures, so it is necessary to study the temperature characteristics of the strain gauge; therefore, by using the same conditions as the actual measurement, Measure the voltage change of the strain gauge under the same temperature change in the FDM process, and use the signal processing method to remove the temperature drift according to the temperature drift characteristics of the strain gauge; Step 8. Strain and stress calculation; (1) Stress calculation method, let the stress measurement voltage after removing zero drift and temperature drift be _VL ; Then, V _L =V _ε -Y _l -V ₂ ; In the above formula, V _ε is the voltage of the strain gauge in the printing process, Y _l is the zero point drift voltage, and V ₂ is the temperature drift voltage; The strain ε is:

Stress, F=E*ε; where E is the elastic modulus of the printing material; (2) Write strain and stress calculation software; in the denoising part, Gaussian denoising, median filtering, mean filtering, wavelet denoising, and EMD model decomposition methods are used to remove noise according to the characteristics of the temperature stress data measured in the FDM printing process; The stress calculation part includes zero-drift filtering, temperature-drift filtering, temperature, strain, and stress calculations; and the functions of brush, data scaling, and clock are added to facilitate the processing of the details of the data. 2. a kind of FDM printing process stress detection method according to claim 1, is characterized in that, the step of removing zero drift in described step 6 is: (1) Hardware connection, the working strain gauge R ₁ , compensation strain gauge R ₂ , compensation strain gauge R ₃ , compensation strain gauge R ₄ form a full bridge connection, grind the working strain gauge R ₁ , compensation strain gauge R ₂ , compensation strain gauge At the bottom of the sheet R ₃ and the compensation strain gauge R ₄ , the 4 strain gauges are pasted and fixed on the programmable heating platform (3), the temperature of the heating platform is set to 25°C, and the working strain gauge R ₁ , the compensation strain gauge R ₂ , Compensation strain gauge R ₃ , compensation strain gauge R ₄ zero drift; (2) Data preprocessing, strain gauge drift is divided into two types, one is horizontal zero point drift, the other is slope zero point drift; in the process of strain sampling, set the total strain sampling time as T, the number of samples as N, and the collected The signals are y ₁ -y _n ,

is the sample mean:

where i=1,2,...,N σ _y is the sample variance:

when

is the horizontal zero drift,

is the zero drift of the slope; (2.1) remove the horizontal zero drift, let the voltage signal after removing the zero drift be Y _i ; Then the zero drift voltage is:

Y _i =y(i)-Y _l ; (2.2) Remove slope zero drift: in

is the first mean point,

is the second mean point; N is the number of samples; T is the total sampling time;

in

in

then the slope of the sample data

Then the zero drift voltage is: Y _l =(k*t) Signal Yi after removing slope zero _drift : Y _i =y(i)-Y _l , where i=1, 2, . . . , N. 3. a kind of FDM printing process stress detection method according to claim 1, is characterized in that, the step of removing temperature drift in described step 7 is: (1) Temperature test during the printing process, the FDM printer loads the second part (5), and there is an empty slot at the area to be measured, the temperature measurement area is the same as the measurement position of the strain detection, and the empty slot is the same size as the temperature sensor PT100; Slice and print the second part (5), and pause the printing process when the FDM printer prints to the layer where position (2) is located; use glue to fix the temperature sensor PT100 in the empty slot, the temperature sensor model is PT100; connect the temperature sensor To the temperature transmitter, the temperature transmitter model is ASC605-V2.0, use the acquisition card to record, and record the voltage change of the temperature sensor during the printing process of the FDM printer; (2) The temperature calculation of the area to be measured in the printing process; the temperature transmitter records the voltage change of the temperature sensor as V ₁ ; V ₁ =f(i), where i=1, 2, . . . , N. Then the temperature change of the test point during the printing process is T ₁ ; T ₁ =20*V ₁ ; (3) To determine the temperature drift, the bridge connection mode of the strain gauge adopts a full bridge connection, and the measured temperature change T1 during the FDM printing process is input into the programmable heating platform ( ₃ ), and the temperature of the programmable heating platform (4) is determined at 25 °C unchanged; connect the working strain gauge R ₁ , compensation strain gauge R2, compensation strain gauge R3, compensation strain gauge R4 full bridge circuit to the bridge and connect the strain gauge through the bridge box, connect the strain gauge to the acquisition card, through the acquisition The card records the voltage changes _of the R1 working strain gauge under the temperature change T1 during the FDM printing process, the compensation strain gauge R2, the compensation strain gauge R3, and the compensation strain gauge R4 at _an ambient temperature of 25 °C; record the temperature drift voltage V of the strain gauge ₂ = f(i); where i = 1, 2, . . . , N.

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