Method and device for measuring magnetism of weights by electromagnetic method
Technical Field
The invention relates to the field of weight magnetic measurement, in particular to an electromagnetic weight magnetic measurement method and a measurement device thereof.
Background
With the development of modern sensors and electronic technology, electronic balances and mass comparators have gained more and more widespread use in the field of mass metering. Compared with mechanical balances, these instruments have advantages such as fast weighing speed, less susceptibility to human influence on the weighing result, etc. However, because the working principle of the electronic balance and the mass comparator adopts the principle of electromagnetic force balance compensation, the magnetic field leakage generated by the weight, the magnetic steel of the balance and the coil in the weighing process inevitably generates mutual acting force, and the force and the gravity borne by the weight can not be distinguished, thereby influencing the accuracy of the weighing result.
Current weight verification procedures jjjg 99-2006 require that "prior to performing reduced mass verification, the magnetic properties (permanent polarization and magnetic susceptibility) of the mass standard should be determined to ensure that the magnetic effects are negligible. The weight that fails the magnetic detection must not be subjected to the reduced mass verification. "in the international recommendation OIMLR11l (2004 edition), it is specified that the weight magnetic measurement must precede the weight mass measurement; and if the magnetic measurement result of the weight exceeds the magnetic requirement, the weight mass measurement is not carried out any more. Therefore, the magnetic index of the weight becomes an important factor affecting the weighing accuracy. Today, electronic balances are widely replacing mechanical balances, and people are increasingly paying more attention to the understanding of the influence of the magnetic properties of a weight on the measurement of the mass value of the weight.
All assessments of the magnetic properties of the weights are technically difficult to implement and the existing test methods are nearly effective. The international proposal that OIML R11l (2004 edition) preferentially recommends a use method is to use a susceptibility meter to measure, which is also a measurement method recommended by the verification regulations of JJJG 99-2006 weight and is a main method for domestic weight magnetic measurement. The susceptibility meter method is used for measuring the magnetism of the weight, because the permanent magnet is used for generating a magnetic field, the permanent magnet needs to be taken out for turning when the direction of the magnetic field is changed during measurement, the original measurement environment is damaged, the distance parameter needs to be measured again by adjusting the weight support when the magnetic field intensity is changed, the workload is large, and the operation is complex.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a method and a device for measuring the magnetism of a weight by an electromagnetic methoddAnd the distance parameters do not need to be measured repeatedly, and all the parameters can be obtained through actual measurement. The measuring environment is not required to be damaged, and the operation is simplified.
The invention is realized by the following technical scheme:
an electromagnetic method weight magnetism measuring device comprises a workbench 1, a weight 2 to be measured, a coil support 3, an electronic balance 4, an inner limiting piece 5, a power supply pack 6, a coil 7, a magnetic sensing body 8, a magnetic sensing body support 9 and an outer limiting piece 10;
workstation 1 includes workstation platform 11 and workstation pillar 12, the weight 2 that awaits measuring is placed on workstation platform 11, 1 inside coil support 3 of having placed of workstation, coil support 3 is connected with workstation 1 through outer locating part 10, coil support 3 includes coil support platform 31 and coil support pillar 32, coil 7 is placed on coil support platform 31 and is connected through wire and power pack 6, coil support pillar 32 is connected through interior locating part 5 and electronic balance 4, interior locating part 5 inlays in outer locating part 10, place induction body support 9 on electronic balance 4's the pan scale, place induction body 8 on induction body support 9, induction body 8 passes coil support platform 31 and extends to coil 7's inside.
Further, the workbench support post 12 comprises a workbench upper post 121, a workbench lower post 122, a bolt 123, an upper adjustment 124 and a lower adjustment 125, the workbench upper post 121 comprises a first upper post 1211, a second upper post 1212 and a third upper post 1213, the first upper post 1211 is connected with the workbench platform 11, the first upper post 1211, the second upper post 1212 and the third upper post 1213 are sequentially connected, the second upper post 1212 is provided with scales, the second upper post 1212 is connected with the upper end of the workbench lower post 122 through the bolt 123, the third upper post 1213 is inserted into the upper end of the workbench lower post 122, the upper adjustment 124 is connected with the lower adjustment 124 at the lower end of the workbench lower post 122, the upper adjustment 124 is connected with the lower adjustment 125, and both the upper adjustment 124 and the lower adjustment 125 are provided with surface straight lines.
Further, the coil support pillar 32 includes an upper pillar 321, a middle pillar 322, a lower pillar 323, an adjusting screw 324 and a cross half-head screw 325, the coil support platform 31 is connected with the upper pillar 321, the upper pillar 321 is connected with the middle pillar 322 through the adjusting screw 324, the middle pillar 322 is connected with the lower pillar 323 through the cross half-head screw 325, and the lower pillar 323 is provided with a scale.
Further, the number of the table legs 12 and the number of the coil support legs 32 are plural.
Further, the magnet sensing body support 9 comprises a lower bottom disc 91 and a cylinder 92, a groove 921 is arranged on the cylinder 92, the magnet sensing body 8 is placed in the groove 921, and the lower bottom disc 91 is matched with a scale pan of the electronic balance 4.
Further, the worktable 1, the coil support 3, the inner limit piece 5, the magnetosensitive body support 9 and the outer limit piece 10 are made of nonmagnetic materials 2a 12; the inductive magnet 8 comprises 1J85 polonium alloy.
A method for realizing magnetic measurement of a weight to be measured by an electromagnetic weight magnetic measurement device comprises the following steps:
step 1, placing the weight 2 to be measured on a workbench platform 11, and measuring the distance Z from the bottom of the weight 2 to be measured to the center of the coil 7 at the center right above the coil 70Radius R of weight 2 to be measuredWHeight h of the weight 2 to be measured, and distance Z from the top of the weight 2 to be measured to the center of the coil 71;
Step 2, turning on a power supply, and measuring a magnetic field H generated on the upper surface of the workbench 1 by using a gauss meter;
step 3, taking down the weight 2 to be measured, and zeroing the electronic balance 4;
step 4, newly combiningThe weight 2 to be measured is placed on the workbench platform 11 and at the center right above the coil 7, and after the numerical value of the electronic balance 4 is stable, the loading time t is recorded1Reading time t2And time of unloading t3Hold t1、t2、t3The measurement was repeated a plurality of times without change, and the average value Δ m of the mass change displayed on the electronic balance 4 was calculated1Calculating the force F generated by the external magnetic field of the weight 2 to be measured1=-Δm1X g, wherein g is the local gravitational acceleration value;
step 5, taking down the weight 2 to be measured, replacing the current direction, repeating the step 4, and calculating the average value delta m of the mass change displayed by the electronic balance 42Calculating the force F generated by the external magnetic field of the weight 2 to be measured2=-Δm2×g;
Step 6, calculating the force of the weight 2 to be measured generated by the external magnetic field by using the calculation results of the step 4 and the
step 5
Calculating the weight 2 to be measured generated by the external magnetic field by using the measurement results of the step 1 and the step 2
Wherein mu
0Permeability in vacuum: mu.s
0=4π×10
-7NA
-2,
Calculating a geometric correction factor I using the results of the measurements of step 1aAnd Ib,
Step 7, solving the magnetic susceptibility χ and the permanent magnetization Mz of the weight to be measured by utilizing the calculation result of the step 6,
wherein, BEZIs the vertical component of the magnetic field strength in the atmosphere.
Further, the method is suitable for the magnetic measurement of grade weights of E2, F1 and F2 of 0.001 kg-5 kg.
Further, in the step 2, when measuring the E2 grade weight, the magnetic field H is less than or equal to 800Am-1When F1 and F2 grade weights are measured, the magnetic field H is less than or equal to 200Am-1。
Compared with the prior art, the invention has the beneficial effects that: in the susceptibility meter method, an electromagnetic coil is adopted to replace a permanent magnet, the magnetic field intensity and the magnetic field direction are controlled by changing the magnitude and the direction of current, the magnetic susceptibility and the magnetic intensity of the weight are calculated by measuring the force of the magnetic field acting on the weight, the measurement environment is not required to be damaged, and the operation is simplified; the lower bottom disc of the induction magnet bracket is matched with the scale pan of the electronic balance, so that the influence of balance unbalance loading can be eliminated, and the induction magnet magnetic core can be placed and clamped by the groove designed in the induction magnet bracket to be stable and positioned in the center; all parameters of a theoretical calculation formula in the method for realizing the magnetic measurement of the weight to be measured by the electromagnetic weight magnetic measurement device can be obtained by actual measurement, and the electromagnetic coil has no magnetic moment mdAnd the distance parameters do not need to be measured repeatedly, so that the magnetic properties of weights with different grades can be measured quickly.
Drawings
FIG. 1 is a schematic structural view of a magnetic measuring device for weights by an electromagnetic method;
FIG. 2 is a perspective view of the structure of the magnetic measuring device for weights by an electromagnetic method;
FIG. 3 is a schematic view of a workbench structure in the magnetic measuring device for weights by an electromagnetic method;
FIG. 4 is a schematic diagram of a coil support structure in an electromagnetic weight magnetic measurement device;
FIG. 5 is a schematic view of a structure of a support of a sensing magnet in the magnetic measuring device of the electromagnetic weight;
FIG. 6 is a schematic diagram of the upper column structure of the column of the workbench in the magnetic measuring device for the weight by the electromagnetic method;
in the drawings, the components represented by the respective reference numerals are listed below:
1. the device comprises a workbench, 2, a weight to be measured, 3, a coil support, 4, an electronic balance, 5, an inner limiting part, 6, a power supply set, 7, a coil, 8, a magnetosensitive body, 9, a magnetosensitive body support, 10, an outer limiting part, 11 workbench platforms, 12 workbench pillars, 121, workbench upper pillars, 1211, a first upper pillar, 1212, a second upper pillar, 1213, a third upper pillar, 122, a workbench lower pillar, 123, bolts, 124, an upper adjustment, 125, a lower adjustment, 31, a coil support platform, 32, a coil support pillar, 321, an upper pillar, 322, a middle pillar, 323, a lower pillar, 324, an adjustment screw, 325, a half-round head screw, 91, a lower bottom disc, 92, a cylinder, 921 and a groove.
Detailed Description
The principles and features of the present invention are described below in conjunction with the following drawings.
As shown in fig. 1, 2, 3, 4 and 5, an electromagnetic method weight magnetism measuring device comprises a workbench 1, a weight 2 to be measured, a coil bracket 3, an electronic balance 4, an inner limiting piece 5, a power pack 6, a coil 7, a magnetic induction body 8, a magnetic induction body bracket 9 and an outer limiting piece 10; the workbench 1 comprises a workbench platform 11 and a workbench pillar 12, the weight 2 to be measured is placed on the workbench platform 11, the workbench 1 comprises a coil bracket 3, an electronic balance 4 and an inner limiting piece 5, coil 7, the magnet sensing body 8, magnet sensing body support 9 and outer locating part 10 are lived, coil support 3 includes coil support platform 31 and coil support pillar 32, coil 7 places on coil support platform 31 and connects through wire and power pack 6, coil support 3 is lived magnet sensing body 8 and magnet sensing body support 9, it has the aperture to open on coil support platform 31, magnet sensing body 8 passes coil support platform 31 and extends to the inside of coil 7, magnet sensing body 8 places on magnet sensing body support 9, magnet sensing body support 9 places on the balance scale of electronic balance 4, coil support 3 is connected with workstation 1 through outer locating part 10, coil support 3 is connected with electronic balance 4 through interior locating part 5.
As shown in fig. 3 and 6, the table support 12 includes a table upper column 121, a table lower column 122, a bolt 123, an upper adjustment 124 and a lower adjustment 125, the table upper column 121 includes a first upper column 1211, a second upper column 1212 and a third upper column 1213, which are connected in sequence, the first upper column 1211 is connected to the table platform 11, the second upper column is provided with scales, the second upper column 1211 is connected to the upper end of the table lower column 122 through the bolt 123, the height of the table support 12 can be adjusted through a height positioning bolt, the third upper column 1213 is inserted into the table lower column 122, the lower end of the table lower column 122 is connected to the upper adjustment 124, the upper adjustment 124 is connected to the lower adjustment 125, the upper adjustment 124 and the lower adjustment 125 are both provided with surface rolling straight lines, and the upper adjustment 124 and the lower adjustment 125 can realize the horizontal adjustment of the table 1.
As shown in fig. 4, the coil support pillar 32 includes an upper pillar 321, a middle pillar 322, a lower pillar 323, an adjusting screw 324, and a cross half-head screw 325, the coil support platform 31 is connected to the upper pillar 321, the upper pillar 321 is connected to the middle pillar 322 through the adjusting screw 324, the middle pillar 322 is connected to the lower pillar 323 through the cross half-head screw 325, and the lower pillar 323 is provided with scales, so that the height adjustment of the coil support pillar 32 can be realized.
As shown in fig. 5, the magnetic sensor holder 9 includes a lower disc 91 and a cylinder 92, the upper end of the cylinder 92 has a groove 921, the magnetic sensor 8 is clamped in the groove 921 to ensure stability and be located at the center, the lower disc 91 is matched with the scale pan of the electronic balance 4, which is beneficial to eliminating the influence of unbalance loading of the balance.
As shown in fig. 2, the coil support 3 is connected with the workbench 1 through an outer limiting part 10, the inner limiting part 5 is embedded in the outer limiting part 10, the coil support 3 is connected with the electronic balance 4 through the inner limiting part 5, a circular groove is formed in the surface of the inner limiting part 5, and the circular groove is matched with the electronic balance 4, so that the devices can be mutually matched and normally work within a current variation range.
The device and the measuring method are suitable for magnetic measurement of E2, F1 and F2 grade weights of 0.001 kg-5 kg, and the core technology of the specific measuring process lies in the stability and accuracy of a controllable electromagnetic field. The stability and accuracy of the electromagnetic field are mainly determined by three parts, namely current, a coil and an induction magnet.
Specifically, the power supply set comprises a power supply and a digital multimeter, and can accurately control output current when supplying power to the coil, so that the aim of accurately adjusting and controlling the magnetic field intensity of the coil is fulfilled.
Exemplary, coil design:
when the current of the toroidal coil is I, the axial magnetic induction at a point (R, θ) near the origin of coordinates (spherical coordinate component, and R < R) is:
wherein, mu0Is magnetic permeability constant β is position parameter of circular coil Ln(β) is the n-order magnetic field coefficient of the toroidn(cos θ) is a Legendre polynomial.
1) Position parameter of toroid
If the vertical distance from the plane of the circular coil to the coordinate origin is h, the position parameter of the circular coil is β h/R;
2) magnetic field coefficient of toroidal coil
The magnetic field coefficient satisfies Ln(-β)=(-1)nLn(β);
3) Legendre polynomial
Wherein, | Pn(x)|≤1(|x|≤1);P0(x) 1 is ═ 1; on the axis of the toroid, Legendre polynomials can take an extreme value.
Axial magnetic field generated by circular coil at origin of coordinates
When the coil radius R is 35mm and h is 6mm, the position parameter β of the torus coil is h/R1/6, and the coil current I is 70 a.i. nI1. Wherein, I1When the number of turns n is 100, the coil gauge is designed to be 10 × 10, 0.4 wire, 0.7A.
Exemplary, the design of the magnetosensitive body and its holder:
the sensing magnet comprises a high permeability polonium resin 1J85 with a density of 8.75g/cm3(ii) a The stent is made of non-magnetic material 2A12 with a density of 2.78g/cm3. Illustratively, the electronic balance weighs 22g at maximum and the coil keel has a minimum inner diameter of 3 mm. The total weight of the magnetic sensing body and the bracket is lower than the maximum weighing of the electronic balance, and the diameter of the magnetic sensing body is smaller than the minimum inner diameter of the coil keel. The induction magnet is designed to be a cylinder with the diameter of 2.5mm and the height of 30 mm.
Specifically, the weight workbench, the coil support, the inner limiting piece and the outer limiting piece are made of nonmagnetic materials 2A12, so that the influence of the materials on an electromagnetic field can be ignored.
Specifically, during actual measurement work, the atmospheric temperature of a working environment is kept at 18-23 ℃, and the maximum change is 1 ℃ every 4 hours; the relative humidity of the atmosphere (30-70)% RH is changed by 10% RH at maximum every 4 hours, and the device is far away from a vibration source and a magnetic source.
An electronic balance with a scale division value of 1 mug is selected, a power supply with voltage of 2mV and current of 1mA is selected, a 10 x 10 and 0.4 coil is selected, and a magnetic sensing body with the cylinder diameter of 2.5mm and the height of 30mm is selected for magnetic measurement of the weight 2 to be measured.
Step 1, placing the weight 2 to be measured on a workbench platform 11, and measuring the distance Z from the bottom of the weight 2 to be measured to the center of the coil 7 at the center right above the coil 70Radius R of weight 2 to be measuredWHeight h of the weight 2 to be measured, and distance Z from the top of the weight 2 to be measured to the center of the coil 71;
Step 2, turning on a power supply, measuring a magnetic field H generated on the upper surface of the workbench 1 by using a gauss meter, and when measuring E2 grade weights, the magnetic field H is less than or equal to 800Am-1When F1 and F2 grade weights are measured, the magnetic field H is less than or equal to 200Am-1;
Step 3, taking down the weight 2 to be measured, and zeroing the electronic balance 4;
step 4, the weight 2 to be measured is placed on the workbench again and is arranged at the center right above the coil 7, and after the numerical value of the electronic balance 4 is stable, the loading time t is recorded1Reading time t2And time of unloading t3Hold t1、t2、t3The measurement was repeated a plurality of times without change, and the average value Δ m of the mass change displayed on the electronic balance 4 was calculated1Calculating the force F generated by the external magnetic field of the weight 2 to be measured1=-Δm1X g, wherein g is the local gravitational acceleration value;
step 5, taking down the weight 2 to be measured, replacing the current direction, repeating the step 4, and calculating the average value delta m of the mass change displayed by the electronic balance 42Calculating the force F generated by the external magnetic field of the weight 2 to be measured2=-Δm2×g;
Step 6, calculating the force of the weight 2 to be measured generated by the external magnetic field by using the calculation results of the step 4 and the
step 5
Calculating the weight 2 to be measured generated by the external magnetic field by using the measurement results of the step 1 and the step 2
Wherein mu
0Permeability in vacuum: mu.s
0=4π×10
-7NA
-2,
Calculating a geometric correction factor I using the results of the measurements of step 1aAnd Ib,
Step 7, solving the magnetic susceptibility χ and the permanent magnetization Mz of the weight to be measured by utilizing the calculation result of the step 6,
although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the spirit and scope of the present invention.