A kind of metal detection machineTechnical field
The present invention relates to a kind of detecting instrument, more particularly, to the detection machine that can detect metallics in product to be checked.
Background technology
At present, metal detection machine is widely used in the testing process in the fields such as food, medicine, makeup, weaving, chemical industryIn, the metal impurities being mixed with product in above-mentioned industry production line or raw material can be detected and excluded automatically, ensure productQuality.It is different according to the shape of detected product and packaging, involved metal detection machines include planer-type conveyer belt conveying-type,Powder type freely falling body conveying-type and fluid line conveying-type, its operation principle are all substantially similar, using metal for magneticInterference detect, but be due to some products to be measured in itself equally exist influence for magnetic field, may result in detectionAs a result it is not accurate enough, cause missing inspection or false retrieval.
The content of the invention
It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art and provide a kind of accuracy of detection is highMetal detection machine.
The purpose of the present invention can be achieved through the following technical solutions：
A kind of metal detection machine, including signal generating module, signal receiving module, carrier wave adjustment module, signal condition mouldBlock and detection judge module, described signal receiving module, carrier wave adjustment module, Signal-regulated kinase and detection judge module according toSecondary connection；
Signal generating module launches sine wave signal, and the electromagnetic field of alternation is produced in detection zone, and product to be checked is passed throughThe region, makes the electromagnetic field of alternation change, and signal receiving module exports sine wave signal to load according to the change of electromagnetic fieldRipple adjustment module, input detection judge module after the signal is handled through carrier wave adjustment module and Signal-regulated kinase, when production to be checkedWhen containing metal in product, under the metal function, the electromagnetic field of alternation, which is produced, largely to be changed, and carrier wave adjustment module is receivedViolent change occurs for the signal arrived, then the signal of input detection judge module changes therewith, by the amplitude of the signal with setting in advanceWhether fixed threshold limit value is compared, judge product to be checked containing gold
Described signal generating module includes transmission signal control unit, transmission signal generator and the hair being sequentially connectedRay circle, described transmission signal control unit control transmission signal generator produces sine wave signal, and is entered by transmitting coilRow transmitting, so as to produce the electromagnetic field of alternation in detection zone.
Described signal receiving module is arranged on around detection zone, is included in the configured around described detection zoneOne receiving coil and the second receiving coil, the first receiving coil and the second receiving coil are exported and electromagnetic field in detection zone jointlyThe corresponding signal of change.
Described carrier wave adjustment module and Signal-regulated kinase are provided with two bars links, respectively the first signal link andSecondary signal link, the output signal of the first signal link is used to be compared with threshold limit value set in advance, judges to be checkedWhether product contains metal, and the output signal of secondary signal link changes over time the influence brought for eliminating product effect.
Described carrier wave adjustment module includes carrier phase control unit, first carrier signal generator, the second carrier wave letterNumber generator, the first multiplier, the second multiplier, described carrier phase control unit connect the generation of first carrier signal respectivelyDevice and the second carrier signal generator, control the carrier signal of output, and described Signal-regulated kinase includes the first filter and amplificationUnit, the second filter and amplification unit, the first A/D units, the 2nd A/D units；
First signal link is by first carrier signal generator, the first multiplier, the first filter and amplification unit and the first A/DUnit is constituted, and the input of the first multiplier connects signal receiving module and first carrier signal generator, the first multiplication respectivelyThe output end of device is sequentially connected the first filter and amplification unit and the first A/D units, and the signal of signal receiving module output is through carrier waveAfter processing, it is filtered successively after amplification and A/D conversions, output to detection judge module；
Secondary signal chain route the second carrier signal generator, the second multiplier, the second filter and amplification unit and the 2nd A/DUnit is constituted, and the input of the second multiplier connects signal receiving module and the second carrier signal generator, the second multiplication respectivelyThe output end of device is sequentially connected the second filter and amplification unit and the 2nd A/D units, and the signal of signal receiving module output is through carrier waveAfter processing, it is filtered successively after amplification and A/D conversions, output to detection judge module.
First carrier signal generator output amplitude is that B, frequency are that f, phase are ψ+α in the first described signal linkSine wave signal SIN_CARRIER1=Bsin (2 π ft+ ψ+α), then finally enter the signal of detection judge module
The second carrier signal generator output amplitude is that B, frequency are that f, phase are ψ+alpha+beta in described secondary signal linkSine wave signal SIN_CARRIER2=Bsin (2 π ft+ ψ+alpha+beta), then finally enter detection judge module signal SIN_2Can be with
In formula, θp(t) it is product effect parameter, passes through the processing to secondary signal chain output signal so that δ+θp(t)-α levels off toEliminate product effect and change over time the influence brought；
Detect that judge module is to the processing procedure of secondary signal chain output signal：
1) it is alpha+beta to update α, then resets β；
2) adjust β value, double step-length, and judge β absolute value whether more than four times step-lengths, if it has, then holdingRow step 1)；If it has not, then performing step 3)；
3) product effect peak value of the top n qualified products in detection process is counted, and is averaged value and is designated as hData_Aver, the average value of previous statistical result is designated as hData_aver_old；
4) judge whether hData_aver is more than hData_aver_old, if it has not, then performing step 2)；If it has, thenPerform step 5)；
5) adjust β value, reduce one times of step-length, and judge β absolute value whether more than four times step-lengths, if it has, then holdingRow step 1)；If it has not, then performing step 6)；
6) product effect peak value of the top n qualified products in detection process is counted, and is averaged value and is designated as hData_Aver, the average value of previous statistical result is designated as hData_aver_old；
7) judge whether hData_aver is more than hData_aver_old, if it has not, then performing step 5)；If it has, thenPerform step 2).
Compared with prior art, present invention tool is used for by two bars links with the output signal of a bars linkIt is compared with threshold limit value set in advance, judges whether product to be checked contains metal, with the output of another bars linkSignal eliminates product effect and changes over time the influence brought so that the result of Product checking is more accurate.
Brief description of the drawings
Fig. 1 is structural representation of the invention；
In figure, 11 be transmission signal control unit, 12 be transmission signal generator, 13 be transmitting coil, 2 be signal receiveModule, 31 are that carrier phase control unit, 32a are that first carrier signal generator, 33a are that the first multiplier, 41a are the first filterRipple amplifying unit, 42a are the first A/D units, and a is the first signal link, and 2b is that the second carrier signal generator, 33b are secondMultiplier, 41b are that the second filter and amplification unit, 42b are the 2nd A/D units, and b is secondary signal link, and 5 judge mould for detectionBlock；
Fig. 2 is process flowchart of the present invention detection judge module to secondary signal chain output signal.
Embodiment
The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.
Embodiment
As shown in figure 1, a kind of metal detection machine, including signal generating module, signal receiving module 2, carrier wave adjustment module,Signal-regulated kinase and detection judge module 5, signal receiving module 2, carrier wave adjustment module, Signal-regulated kinase and detection judgeModule 5 is sequentially connected.
Wherein, signal generating module include be sequentially connected transmission signal control unit 11, transmission signal generator 12 withAnd transmitting coil 13, the generation sine wave signal of the control transmission signal of transmission signal control unit 11 generator 12, and by emission linesCircle 13 is launched, so as to produce the electromagnetic field of alternation in detection zone.Signal receiving module 2 is included in described detection zoneThe first receiving coil and the second receiving coil configured around domain, the two exports corresponding sine according to according to the change of electromagnetic fieldRipple signal.
Carrier wave adjustment module and Signal-regulated kinase are provided with two bars links, respectively the first signal link a and secondSignal link b, the output signal of the first signal link is used to be compared with threshold limit value set in advance, judges product to be checkedWhether metal is contained, and the output signal of secondary signal link changes over time the influence brought for eliminating product effect.Carrier waveAdjustment module includes carrier phase control unit 31, first carrier signal generator 32a, the second carrier signal generator 32b, theOne multiplier 33a, the second multiplier 33b, carrier phase control unit 31 connect first carrier signal generator 32a and respectivelyTwo-carrier signal generator 32b, controls the carrier signal of output, and Signal-regulated kinase includes the first filter and amplification unit 41a, theTwo filter and amplification unit 41b, the first A/D units 42a, the 2nd A/D units 42b.
First signal link a is by first carrier signal generator 32a, the first multiplier 33a, the first filter and amplification unit41a and the first A/D units 42a compositions, the first multiplier 33a input connects signal receiving module 2 and first carrier respectivelySignal generator 32a, the first multiplier 33a output end are sequentially connected the first filter and amplification unit 41a and the first A/D units42a, the signal that signal receiving module 2 is exported is filtered after carrier processing, successively after amplification and A/D conversions, and output is extremelyDetect judge module 5；
Secondary signal chain route the second carrier signal generators of b 32b, the second multiplier 33b, the second filter and amplification unit41b and the 2nd A/D units 42b compositions, the second multiplier 33b input connects the carrier wave of signal receiving module 2 and second respectivelySignal generator 32b, the second multiplier 33b output end are sequentially connected the second filter and amplification unit 41b and the 2nd A/D units42b, the signal that signal receiving module 2 is exported is filtered after carrier processing, successively after amplification and A/D conversions, and output is extremelyDetect judge module 5.
The course of work of the present invention is as follows：
It is that A, frequency are the sine wave signal SIN_T that f, phase are ψ and via transmitting that transmission signal generator, which produces amplitude,Coil T launches.SIN_T is represented with formula Asin (2 π ft+ ψ).
It is that B, frequency are that f, phase are ψ+α that carrier phase control unit, which controls first carrier signal generator to produce amplitude,Sine wave signal SIN_CARRIER1 simultaneously sends into the first multiplier, and SIN_CARRIER1 carrys out table with formula Bsin (2 π ft+ ψ+α)Show.
Receiving coil A and B is excited by signal SIN_T and output amplitude is A1, the sinusoidal signal that frequency is f, phase is ψ+δSIN_R.SIN_R is represented with formula Alsin (2 π ft+ ψ+δ).
SIN_R and SIN_CARRIER1 is input in multiplier 1 jointly, the output signal SIN_M1 of multiplier 1.SIN_M1 withFormulaTo represent.
SIN_M1 is changed into data SIN_1 by LPF with amplifying element and A/D links.SIN_1 is with formulaTo represent.
Qualified product to be checked is by detection zone, i.e., during the region that the probe being made up of transmitting, receiving coil is covered,Also different degrees of influence will be produced to the electromagnetic field in the range of probe.This causes signal SIN_R to be changed into A1_Pgsin (2 π ft+ ψ+δ+θp(t)).Further, this will cause signal SIN_1 to be changed into
Want compacted products effect, it is necessary to
δ is a parameter relevant with the sonde configuration of detection machine, and for the probe made, δ is basically unchanged.θp(t)It is a parameter relevant with product, for different product, θ for product effect parameterp(t) it is different；For production of the same raceProduct, change over time, θp(t) it is also possible to change.This is requiredWhen α meets this requirementWhen, product effect is to be pressed into minimum.
The product effect parameter θ of metal productp(t) it is θmetal, will be dry when the substandard product with metal is by popping one's head inThe magnetic distribution in the range of probe is disturbed, this causes signal SIN_R to be changed into A1_Mgsin (2 π ft+ ψ+δ+θmetal).Further, thisSignal SIN_1 will be caused to be changed into(the superposition of product effect is not showed here,Because product effect has typically been pressed to the amplitude of very little).Foregoing product compacting provides constraint for α, as long as in αRestriction range in, and SIN_1 amplitude reaches default threshold limit value, that is, judges that product contains metallic foreign body.
But, due to product effect parameter θp(t) change over time and change, for some products, this change is outstandingIt is obvious, so that after a period of time, θp(t) change by cause qualified products product effect exceed threshold value, and then byExcluded as substandard product, it is therefore desirable to θ p are eliminated by the signal of secondary signal link(T) change over time and broughtInfluence.
The input of second multiplier is derived from input SIN_R and the carrier phase control unit control of above-mentioned signal receiving moduleAmplitude produced by second carrier signal generator of system is B, the sine wave signal SIN_ that frequency is f, phase is ψ+alpha+betaCARRIER2。
Secondary signal link output signal SIN_2 after A/D links.Similarly, signal SIN_2 can be withAnd judge module is detected to signal SIN_2 processing, update carrier signal generator defeatedGo out the phase α of signal, you can the control to product effect is realized, so as to improve the degree of accuracy of detection.
Specific handling process is as shown in Fig. 2 comprise the following steps：
1) it is alpha+beta to update α, then resets β；
2) adjust β value, double step-length, and judge β absolute value whether more than four times step-lengths, if it has, then holdingRow step 1)；If it has not, then performing step 3)；
3) product effect peak value of the top n qualified products in detection process is counted, and is averaged value and is designated as hData_Aver, the average value of previous statistical result is designated as hData_aver_old；
4) judge whether hData_aver is more than hData_aver_old, if it has not, then performing step 2)；If it has, thenPerform step 5)；
5) adjust β value, reduce one times of step-length, and judge β absolute value whether more than four times step-lengths, if it has, then holdingRow step 1)；If it has not, then performing step 6)；
6) product effect peak value of the top n qualified products in detection process is counted, and is averaged value and is designated as hData_Aver, the average value of previous statistical result is designated as hData_aver_old；
7) judge whether hData_aver is more than hData_aver_old, if it has not, then performing step 5)；If it has, thenPerform step 2).
Wherein, step-length can specifically be set according to the product effect parameter of different product, can so obtain accurateTesting result.