Data processing system of welding thermal efficiency measuring device

Abstract

The invention discloses a data processing system of a welding thermal efficiency measuring device. The system comprises a hardware part and a software part, the hardware mainly comprises a PXI case, a PXI controller, a PXI module, a current and voltage sensor and a thermocouple, the software takes a virtual instrument platform LabVIEW as a programming tool, a set of data acquisition and analysis software capable of being used for various welding methods is designed, and the software system mainly comprises an acquisition parameter setting module, an acquisition parameter setting module, an acquisition parameter setting module and a data processing module. The system comprises a welding machine electric signal acquisition module, an initial temperature acquisition module, a device temperature acquisition module, a data echo module, a signal filtering module, a data calculation module, a data correction module and a file operation module. The energy obtained by the whole device is calculated by considering all energy absorption except heat radiation, so that the welding heat efficiency is calculated more accurately. And the welding thermal efficiency measurement result can be improved.

Description

Technical Field

[0001] The invention relates to a data processing system for a welding thermal efficiency measuring device, in particular to a system for detecting thermal efficiency generated during welding. Background Art

[0002] The energy provided by the welding machine cannot be fully utilized by the welding process. Part of the energy will be transferred to the surrounding medium with splashing and other means. When the welding parameters are stable, the welding thermal efficiency should also be relatively stable. However, in the actual welding process, the welding thermal efficiency of some welding methods is a range value, and the range is very large. There are many factors that affect the welding thermal efficiency, the most important of which is the welding method. The influence of the welding method on the welding thermal efficiency is mainly reflected in the stability of the welding parameters and the standardization of the welding. Among all the welding methods, with the automation and intelligence of the welding process, the welding thermal efficiency is also increasing.

[0003] The calculation formula of thermal efficiency is:

[0004]

[0005] U is the arc voltage, I is the welding current, t is the welding time, T1 is the initial value of the temperature, T2 is the final value of the temperature, C is the specific heat capacity, and m is the mass of the object being measured.

[0006] In order to ensure the accuracy of welding thermal efficiency measurement, we choose to use virtual instruments to assist in the measurement. Through virtual instruments, we can ensure the accuracy of the data we measured, thus providing a reliable basis for the accurate calculation of welding thermal efficiency. Summary of the invention

[0007] The present invention is based on sampling theorem, temperature measurement principle, and specific heat capacity principle, and uses a virtual instrument platform to construct a data acquisition and analysis system for welding thermal efficiency measurement. The system includes two parts: hardware and software. The hardware mainly includes a PXI chassis, a PXI controller, a PXI module, a current and voltage sensor, and a thermocouple. The software uses the virtual instrument platform LabVIEW as a programming tool, and designs a set of data acquisition and analysis software that can be used for a variety of welding methods and even composite welding. The software system mainly includes an acquisition parameter setting module, a welding machine electrical signal acquisition module, an initial temperature acquisition module, a device temperature acquisition module, a data echo module, a signal filtering module, a data calculation module, a data correction module, and a file operation module. The system optimizes the measurement of welding thermal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is the hardware system structure of the present invention.

[0009] Figure 2 This is the software system structure of the present invention.

[0010] Figure 3 It is the heat absorption device of the present invention. DETAILED DESCRIPTION

[0011] The technical solution of the present invention is further explained below in conjunction with specific implementation cases:

[0012] like Figure 1 As shown, the hardware system includes welding power supply, voltage sensor, current sensor, temperature sensor, heat absorption device, and data acquisition device. In order to obtain accurate measurement results, the temperature sensor in this device uses K-type thermocouple, which has good linearity, large thermoelectric potential, high sensitivity, good stability and uniformity, strong anti-oxidation performance and wide measurement range (0-1300℃). In order to reduce the loss of heat through radiation, two layers of insurance are made: one is to add a copper plate during the water circulation process, and make the inside of the copper plate into a U-shaped groove for water circulation. The copper plate has good thermal conductivity. The copper plate is used to guide the heat on the workpiece into the water faster, so as to reduce the loss of heat caused by radiation; the second is to add two layers of insulation in the design, which is also to reduce thermal radiation and ensure the accuracy of heat collection of the entire device. When the temperature of the copper plate and the weldment is equal, it is determined that the thermal equilibrium state is reached. A thermocouple is placed at the water outlet of the water tank to measure the temperature of the water in the water tank; thermocouples are placed on the cover insulation cotton and the water tank insulation cotton. The temperature rise of the cover insulation cotton is large and needs to be measured separately. The thickness of the insulation cotton around the water tank is the same, and only one thermocouple is used to measure the water tank insulation cotton; thermocouples are arranged on the welding plate and the copper plate to determine the thermal equilibrium state. A thermocouple is placed in the center of each of the four sides of the weldment, and a thermocouple is placed in the center of the bottom of the copper plate. Hall sensors are selected as voltage and current sensors to ensure the accuracy, sensitivity, responsiveness and stability of the system's acquisition signals. The data acquisition card involves two modules: electrical signal data acquisition and temperature acquisition. For the electrical signal output by the welding power supply, the NI PXIe-6361 data acquisition board in the PXI multi-function I / O module is used for acquisition. For the acquisition of temperature signals, the NI PXIe-4353 data acquisition board in the PXI temperature input module is used. The welding machine has at least four channels for collecting electrical signals. Four even points are placed on the copper plate, one for the weldment, one for the water inlet and outlet of the copper plate, one for the water tank, and two for the thermal insulation cotton, for a total of 10 channels. Select the differential mode as the connection mode. In the differential mode, noise and common-mode voltage can be well suppressed to obtain more accurate values. One input signal will occupy two channels, so 8 channels are required for collecting electrical signals.

[0013] like Figure 2As shown in the figure, the software system consists of three parts: data acquisition, data analysis, and file processing. The machine is debugged according to different welding methods, followed by initial temperature acquisition. The temperature after the water pump is running is no longer accurate, so before the entire program starts, the temperature needs to be collected, followed by electrical signal data acquisition after the test, including the acquisition of voltage, current and electric power, and finally the acquisition of device temperature. The temperature signal is transmitted to the computer through various thermocouples. Data analysis includes data echo module, signal filtering module, data calculation module, and data repair module. After the data measurement is completed, the data of the entire test is integrated and calculated, the data curve of each time period is observed, and the signal is filtered to shield the noise interference in the measurement process. After obtaining accurate data, data calculation begins. In the calculated data, the heat is not only provided by the welding process, and the data needs to be corrected. File processing includes file saving module and file reading module. File saving is the storage of the measured original data. In the subsequent signal processing, the file reading module needs to be used to read the data from the file and then perform corresponding processing.

[0014] In the process of thermal efficiency measurement, 50A DC non-melting inert gas shielded welding was selected. The initial temperature of each part was measured. After the initial temperature measurement was completed, the water pump was turned on for welding. The welding time was 20 seconds. When the program stopped, the welding should also be stopped immediately. The temperature acquisition program was run. The temperature acquisition program was turned on after the welding was completed. After the temperature measurement was completed, the file was read. The experimental calculation results are as follows:

[0015] 1. The total energy absorbed by the device is 33006KJ, the water tank absorbs 22850KJ, the insulation cotton absorbs 0.38KJ, the copper plate absorbs 10155KJ, the welding heat input is 39892KJ, and the welding thermal efficiency is 82.74%.

[0016] 2. The total energy absorbed by the device is 30511KJ, the water tank absorbs 19084KJ, the insulation cotton absorbs 0.365KJ, the copper plate absorbs 11427KJ, the welding heat input is 36479KJ, and the welding thermal efficiency is 83.64%.

[0017] 3. The total energy absorbed by the device is 31421KJ, the water tank absorbs 19382KJ, the insulation cotton absorbs 0.339KJ, the copper plate absorbs 12038KJ, the welding heat input is 37496KJ, and the welding thermal efficiency is 83.8%.

[0018] After analysis, it was found that the welding thermal efficiency values ​​obtained by the system are accurate, the data acquisition and analysis system is easy to operate, the analysis method is comprehensive, the data processing speed is fast, and the file reading and storage are simple.

[0019] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A data processing system for a welding thermal efficiency measuring device, comprising a hardware system and a software system, characterized in that: The hardware system includes welding power supply, voltage sensor, current sensor, temperature sensor, heat absorption device, data acquisition device, and computer; the software system consists of three parts, including data acquisition, data analysis, and file processing.

2. A welding thermal efficiency measurement device data processing system as claimed in claim 1, characterized in that: The data acquisition device involves two modules: electrical signal data acquisition and temperature acquisition. For the electrical signal output by the welding power supply, the NI PXIe-6361 data acquisition board in the PXI multi-function I / O module is used for acquisition. For the acquisition of temperature signals, the NI PXIe-4353 data acquisition board in the PXI temperature input module is used.

3. A welding thermal efficiency measurement device data processing system as claimed in claim 1, characterized in that: The heat absorption device uses a water tank to absorb heat, and adds a copper plate during the water circulation process. The inside of the copper plate is made into a U-shaped groove for water circulation. Two layers of insulation are added to reduce heat radiation to ensure the accuracy of heat collection by the entire device.

4. A welding thermal efficiency measurement device data processing system as claimed in claim 1, characterized in that: After determining the channel and sampling frequency, the electrical signal is collected and the data is stored in the TDMS file. In the channel, the maximum input of the electrical signal is 5V and the minimum is -5V. Before displaying and processing the data, the voltage signal is expanded 12.8 times to obtain the original signal, and the current signal is expanded 100 times to obtain the original current signal.

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