CN105572183A - Measurement method of water content of wet type clay sand based on pure resistance measurement - Google Patents

Measurement method of water content of wet type clay sand based on pure resistance measurement Download PDF

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Publication number
CN105572183A
CN105572183A CN201610123745.6A CN201610123745A CN105572183A CN 105572183 A CN105572183 A CN 105572183A CN 201610123745 A CN201610123745 A CN 201610123745A CN 105572183 A CN105572183 A CN 105572183A
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China
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resistance
green sand
water cut
signal
signal source
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CN201610123745.6A
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Chinese (zh)
Inventor
石德全
裴立新
高桂丽
李大勇
陈志俊
康凯娇
董静薇
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Harbin University of Science and Technology
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Harbin University of Science and Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/122—Circuits particularly adapted therefor, e.g. linearising circuits

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Measurement Of Resistance Or Impedance (AREA)

Abstract

The invention discloses a measurement method of the water content of wet type clay sand based on pure resistance measurement, and relates to the field of casting and solves the problem that when the water content of the wet type sand is measured by a conventional resistance method, the testing precision is low because the resistance is influenced by capacitance parameters. The measurement method is realized through the following steps: (1) assembling a measurement device of the water content of the wet type clay sand based on the pure resistance measurement, wherein the measurement device consists of a resistance and moisture sensor, a signal conditioning unit, an exciting signal source, an A/D (Analog to Digital) conversion unit, a data communication unit and a computer; (2) assembling a voltage measurement circuit consisting of the resistance and moisture sensor, the signal conditioning unit and the exciting signal source; (3) measuring the resistance and the water content of the wet type clay sand by utilizing the measurement device for measuring the water content and the voltage measurement circuit. According to the method disclosed by the invention, through FFT (Fast Fourier Transform), extraction of a fundamental component of a sampling sequence and separation of a real part and a virtual part of the fundamental component, a value of the real part of the fundamental component related only to the resistance can be obtained, so that the resistance and the water content of the wet type sand can be precisely obtained.

Description

A kind of measuring method of the green sand water cut based on pure resistance measurement
Technical field
What the present invention relates to is casting field, specifically a kind of measuring method of the green sand water cut based on pure resistance measurement.
Background technology
Because having, operation is simple in green sand casting, throughput rate advantages of higher is still casting method main at present, and the performance of green sand and stability thereof directly affect quality and the production cost of foundry goods.In each component of green sand and performance index, moisture is that affecting green sand quality main is also one of the most responsive parameter.At present, electric-resistivity method is the method for fast measuring using more green sand water cut, its ultimate principle is under driving source effect, the change of sensor resistance can be caused during change of moisture content according to tested green sand, by recording the resistance value of green sand, then calculate the size of water cut according to the existing relation between the water cut of green sand and resistance value.Compared with DC resistance method, although AC resistance method effectively reduces the impact of green sand polarization, but under electric field action, green sand shows resistive and capacitive character simultaneously, therefore water cut is calculated by measured resistance value, the interference of electric capacity must be subject to, the measuring accuracy of green sand water cut certainly will be reduced.And electric resistance sensor is often seen as ideal resistance by the existing measurement mechanism based on electric-resistivity method, the impact by electric capacity is ignored, and also just causes water cut measuring accuracy and is difficult to improve.Therefore, provide a kind of measuring method of the green sand water cut based on pure resistance measurement significant.
Summary of the invention
The present invention is to solve the not high problem of existing resistance measurement green sand water cut precision, and provides a kind of measuring method of the green sand water cut based on pure resistance measurement.
The measuring method of a kind of green sand water cut based on pure resistance measurement of the present invention is implemented through the following steps:
One, assemble the measurement mechanism of the green sand water cut measured based on pure resistance: based on the measurement mechanism of the green sand water cut that pure resistance is measured, it is by resistance moisture transducer, signal condition unit, exciting signal source, A/D converting unit, data communication units and computing machine are formed, wherein the signal output part of resistance moisture transducer is connected with a signal input part of signal condition unit, the pumping signal output terminal of exciting signal source is connected with another signal input part of signal condition unit, be connected with a signals collecting input end of A/D converting unit simultaneously, the signal output part of signal condition unit is connected with another signals collecting input end of A/D converting unit, the signal output part of A/D converting unit is connected with the signal input part of data communication units, the signal output part of data communication units is connected with the signal input part of computing machine.
Two, assemble the tension measuring circuit be made up of resistance moisture transducer, signal condition unit, exciting signal source: the tension measuring circuit be made up of resistance moisture transducer, signal condition unit, exciting signal source, it comprises amplifier, balance resistance, feedback resistance, green sand equivalent resistance R x, green sand equivalent capacity C xwith sine wave exciting signal source U i, the wherein inverting input of amplifier A and feedback resistance R fone end be connected, simultaneously with green sand resistance R xwith green sand electric capacity C xone end be connected, the output terminal of amplifier A and feedback resistance R fthe other end be connected, the in-phase input end of amplifier A and balance resistance R 0one end be connected, balance resistance R 0the other end and sine wave exciting signal source U ione end be connected, sine wave exciting signal source U ithe other end and green sand resistance R xwith green sand electric capacity C xthe other end be connected, simultaneously ground connection, the output terminal output voltage U of amplifier A 0with sine wave exciting signal source U iconnect A/D converting unit.
Three, measurement mechanism and tension measuring circuit is utilized to measure resistance and the water cut of green sand: inserted by resistance moisture transducer in tested green sand, exciting signal source produces sine wave exciting signal U i=U imsin (ω t), at sine wave exciting signal U iinitial phase be the moment of 0, A/D converting unit is to the output terminal output voltage U of amplifier A 0=a 0cos (ω t+ φ) samples n time, obtains sample sequence U 0(n), and deliver to computing machine by data communication units, computing machine is to sample sequence U 0n () carries out FFT conversion, extract and to fundametal compoment carry out real part and imaginary component from, obtain real component correspond to by formula try to achieve the resistance of green sand , then by existing green sand resistance R xand the relation between water cut, can try to achieve the water cut of green sand.
Preferably, in described step 2, feedback resistance R ftemperature-coefficient of electrical resistance be less than 0.2ppm/ DEG C;
Preferably, in described step 3, sampling number n is the integral number power of 2, so that carry out FFT conversion.
Preferably, in described step 3, at sine wave exciting signal U iphase place be φ iany time, offset of sinusoidal wave excitation signal U i=U imsin (ω t+ φ i) and the output terminal output voltage U of amplifier A 0=a 0cos (ω t+ φ+φ i) sample n time, obtain sample sequence U. simultaneously i(n) and U 0n (), to sample sequence U i(n) and U 0n () all carries out FFT conversion, can try to achieve U in the phase place of the FFT transformation results of () is φ i, U 0n the mould of the FFT transformation results of () is B, phase place is φ+φ i, by (φ+φ i)-φ i=φ can draw the initial phase φ sampled at any time, again because of the modular invariance of any time sampling FFT transformation results, B and φ can be reconfigured and can obtain U 0the FFT conversion of (n).
Advantage of the present invention: by sampling to the output voltage of tension measuring circuit, and deliver to computing machine through data communication units, computing machine carries out FFT conversion to the sample sequence obtained, extract the fundametal compoment of signal, then the real part of fundametal compoment is separated with imaginary part, obtain only relevant to resistance fundametal compoment value of real part, accurately can try to achieve the resistance of green sand, eliminate the interference of green sand electric capacity when traditional resistor method measures green sand water cut, thus substantially increase the measuring accuracy of resistance measurement green sand water cut.
Accompanying drawing explanation
Fig. 1 is that the measurement mechanism of a kind of green sand water cut based on pure resistance measurement in the present invention forms block diagram.
Fig. 2 is the tension measuring circuit schematic diagram be made up of resistance moisture transducer, signal condition unit and exciting signal source in the present invention.
Embodiment
Be described according to Figure of description 1 and accompanying drawing 2 pairs of embodiments of the present invention.
Embodiment one: present embodiment is implemented through the following steps based on the measuring method of the green sand water cut that pure resistance is measured:
One, assemble the measurement mechanism of the green sand water cut measured based on pure resistance: based on the measurement mechanism of the green sand water cut that pure resistance is measured, it is by resistance moisture transducer 1, signal condition unit 2, exciting signal source 3, A/D converting unit 4, data communication units 5 and computing machine 6 are formed, wherein the signal output part of resistance moisture transducer 1 is connected with a signal input part of signal condition unit 2, the pumping signal output terminal of exciting signal source 3 is connected with another signal input part of signal condition unit 2, be connected with a signals collecting input end of A/D converting unit 4 simultaneously, the signal output part of signal condition unit 2 is connected with another signals collecting input end of A/D converting unit 4, the signal output part of A/D converting unit 4 is connected with the signal input part of data communication units 5, the signal output part of data communication units 5 is connected with the signal input part of computing machine 7.
Two, assemble the tension measuring circuit be made up of resistance moisture transducer 1, signal condition unit 2, exciting signal source 3: the tension measuring circuit be made up of resistance moisture transducer 1, signal condition unit 2, exciting signal source 3, it comprises amplifier A, balance resistance R 0, feedback resistance R f, green sand resistance R x, green sand electric capacity C xwith sine wave exciting signal source U i, the wherein inverting input of amplifier A and feedback resistance R fone end be connected, simultaneously with green sand resistance R xwith green sand electric capacity C xone end be connected, the output terminal of amplifier A and feedback resistance R fthe other end be connected, the in-phase input end of amplifier A and balance resistance R 0one end be connected, balance resistance R 0the other end and sine wave exciting signal source U ione end be connected, sine wave exciting signal source U ithe other end and green sand resistance R xwith green sand electric capacity C xother end phase, simultaneously ground connection, the output terminal output voltage U of amplifier A 0with sine wave exciting signal source U iconnect A/D converting unit 4.
Three, measurement mechanism and tension measuring circuit is utilized to measure resistance and the water cut of green sand: inserted by resistance moisture transducer 1 in tested green sand, exciting signal source 3 produces sine wave exciting signal U i=U imsin (ω t), at sine wave exciting signal U iinitial phase be the moment of 0, the output terminal output voltage U of A/D converting unit 4 couples of amplifier A 0=a 0cos (ω t+ φ) samples n time, obtains sample sequence U 0(n), and deliver to computing machine 6 by data communication units 5, computing machine 6 couples of sample sequence U 0n () carries out FFT conversion, extract and to fundametal compoment carry out real part and imaginary component from, obtain real component , correspond to V rmby formula try to achieve the resistance of green sand again by existing green sand resistance R xand the relation between water cut, can try to achieve the water cut of green sand.
Feedback resistance R wherein described in step 2 ftemperature-coefficient of electrical resistance be less than 0.2ppm/ DEG C;
Sampling number n described in step 3 is the integral number power of 2, so that carry out FFT conversion.
In present embodiment, green sand can be equivalent to green sand resistance R in parallel in dotted line frame in the tension measuring circuit that accompanying drawing 2 is made up of resistance moisture transducer 1, signal condition unit 2, exciting signal source 3 xwith green sand electric capacity C x.
Embodiment two: present embodiment and embodiment one are not less than 160kHz unlike the sample frequency of the A/D converting unit 4 described in step one and step 3.Other steps and parameter identical with embodiment one.
Embodiment three: present embodiment and embodiment one or two are unlike the feedback resistance R described in step 2 fvalue be 100k Ω.Other steps and parameter identical with embodiment one or two.
Embodiment four: one of present embodiment and embodiment one to three are unlike the sine wave exciting signal source U described in step 3 ifrequency value be 10kHz.Other steps and parameter identical with one of embodiment one to three.
Embodiment five: one of present embodiment and embodiment one to four are any time unlike the sampling instant described in step 3, corresponding sine wave exciting signal U iphase place be φ i.Other steps and parameter identical with one of embodiment one to four.
In present embodiment, offset of sinusoidal wave excitation signal U i=U imsin (ω t+ φ i) and the output terminal output voltage U of amplifier A 0=a 0cos (ω t+ φ+φ i) sample n time, obtain sample sequence U. simultaneously i(n) and U 0n (), to sample sequence U i(n) and U 0n () all carries out FFT conversion, can try to achieve U in the phase place of the FFT transformation results of () is φ i, U 0n the mould of the FFT transformation results of () is B, phase place is φ+φ i, by (φ+φ i)-φ i=φ can draw the initial phase φ value of sampling at any time, again because of the modular invariance of any time sampling FFT transformation results, B and φ can be reconfigured and can obtain U 0the FFT conversion of (n).
In present embodiment, replace the different green sand of water cut to carry out resistance value test by the standard capacitance of 200pF and the measuring resistance of different resistance, test result is as follows,

Claims (4)

1., based on a measuring method for the green sand water cut of pure resistance measurement, it is characterized in that a kind of measuring method of the green sand water cut based on pure resistance measurement realizes through the following steps:
One, assemble the measurement mechanism of the green sand water cut measured based on pure resistance: based on the measurement mechanism of the green sand water cut that pure resistance is measured, it is by resistance moisture transducer (1), signal condition unit (2), exciting signal source (3), A/D converting unit (4), data communication units (5) and computing machine (6) are formed, wherein the signal output part of resistance moisture transducer (1) is connected with a signal input part of signal condition unit (2), the pumping signal output terminal of exciting signal source (3) is connected with another signal input part of signal condition unit (2), be connected with a signals collecting input end of A/D converting unit (4) simultaneously, the signal output part of signal condition unit (2) is connected with another signals collecting input end of A/D converting unit (4), the signal output part of A/D converting unit (4) is connected with the signal input part of data communication units (5), the signal output part of data communication units (5) is connected with the signal input part of computing machine (7),
Two, the tension measuring circuit be made up of resistance moisture transducer (1), signal condition unit (2), exciting signal source (3) is assembled: the tension measuring circuit be made up of resistance moisture transducer (1), signal condition unit (2), exciting signal source (3), it comprises amplifier A, balance resistance R 0, feedback resistance R f, green sand resistance R x, green sand electric capacity C xwith sine wave exciting signal source U i, the wherein inverting input of amplifier A and feedback resistance R fone end be connected, simultaneously with green sand resistance R xwith green sand electric capacity C xone end be connected, the output terminal of amplifier A and feedback resistance R fthe other end be connected, the in-phase input end of amplifier A and balance resistance R 0one end be connected, balance resistance R 0the other end and sine wave exciting signal source U ione end be connected, sine wave exciting signal source U ithe other end and green sand resistance R xwith green sand electric capacity C xother end phase, simultaneously ground connection, the output terminal output voltage U of amplifier A 0with sine wave exciting signal source U iconnect A/D converting unit (4);
Three, measurement mechanism and tension measuring circuit is utilized to measure resistance and the water cut of green sand: inserted by resistance moisture transducer 1 in tested green sand, exciting signal source 3 produces sine wave exciting signal U i=U imsin (ω t), at sine wave exciting signal U iinitial phase be the moment of 0, A/D converting unit (4) is to the output terminal output voltage U of amplifier A 0=a 0cos (ω t+ φ) samples n time, obtains sample sequence U 0(n), and deliver to computing machine (6) by data communication units (5), computing machine (6) is to sample sequence U 0n () carries out FFT conversion, extract and to fundametal compoment carry out real part and imaginary component from, obtain real component correspond to , by formula try to achieve the resistance of green sand , then by existing green sand resistance R xand the relation between water cut, can try to achieve the water cut of green sand;
Feedback resistance R wherein described in step 2 ftemperature-coefficient of electrical resistance be less than 0.2ppm/ DEG C;
Sampling number n described in step 3 is the integral number power of 2, so that carry out FFT conversion.
2. the measuring method of a kind of green sand water cut based on pure resistance measurement according to claim 1, it is characterized in that, the sample frequency of step one and the A/D converting unit (4) described in step 3 is not less than 160kHz.
3. the measuring method of a kind of green sand water cut based on pure resistance measurement according to claim 1, it is characterized in that, the value of the feedback resistance Rf described in step 2 is 100k Ω.
4. the measuring method of a kind of green sand water cut based on pure resistance measurement according to claim 1, is characterized in that, described sine wave exciting signal source U ifrequency value be 10kHz.
CN201610123745.6A 2016-03-05 2016-03-05 Measurement method of water content of wet type clay sand based on pure resistance measurement Pending CN105572183A (en)

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
CN106290474A (en) * 2016-08-01 2017-01-04 哈尔滨理工大学 A kind of device measuring green sand moisture and water content acquisition methods

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CN101799436A (en) * 2010-03-18 2010-08-11 中国农业大学 Instrument for measuring soil moisture and conductivity based on phase detection and measuring method thereof
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Publication number Priority date Publication date Assignee Title
CN106290474A (en) * 2016-08-01 2017-01-04 哈尔滨理工大学 A kind of device measuring green sand moisture and water content acquisition methods
CN106290474B (en) * 2016-08-01 2023-09-01 哈尔滨理工大学 Device for measuring moisture content of green sand and moisture content acquisition method

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Application publication date: 20160511