CN115508577A - Method for measuring Richter hardness and Shore hardness based on double-coil electromagnetic induction - Google Patents
Method for measuring Richter hardness and Shore hardness based on double-coil electromagnetic induction Download PDFInfo
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- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/64—Devices characterised by the determination of the time taken to traverse a fixed distance
- G01P3/66—Devices characterised by the determination of the time taken to traverse a fixed distance using electric or magnetic means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/64—Devices characterised by the determination of the time taken to traverse a fixed distance
- G01P3/68—Devices characterised by the determination of the time taken to traverse a fixed distance using optical means, i.e. using infrared, visible, or ultraviolet light
Abstract
The invention provides a method for measuring Richter hardness and Shore hardness based on double-coil electromagnetic induction, which comprises the steps of respectively placing an object to be measured and a magnetized impact body at two sides of two closed coils, the magnetized impact body impacts the surface of the object to be measured after passing through the two closed coils at a certain speed, recording the time interval and the speed of the magnetized impact body passing through the two closed coils, and calculating to obtain the hardness of the object to be measured in a Rich scale or Shore scale; <xnotran> , , , , . </xnotran>
Description
Technical Field
The invention relates to the technical field of measurement, in particular to a method for measuring the Richter hardness and the Shore hardness based on double-coil electromagnetic induction.
Background
The Richter hardness is a brand-new hardness measurement method which is firstly proposed by LeEB of Switzerland in 1978, and is defined as follows: the surface of the sample was impacted with an impact body of a predetermined mass at a constant velocity by an elastic force, and the hardness was called "Leeb hardness" because it was named by doctor LEEB, a numerical value calculated from the ratio of the rebound velocity of the punch at a distance of 1mm from the surface of the sample to the impact velocity.
At present, the method for measuring the Richter hardness by domestic manufacturers is that an impact body generates an induction voltage when approaching a closed coil, the voltage value U = B multiplied by L multiplied by v, according to the electromagnetic principle, when the magnetized impact body approaches the closed coil and reaches a certain position, the induction voltage reaches the maximum value, under the ideal state, the distance from the impact body to a material is 1mm, the impact body rebounds after impacting the surface of the material, and when the distance from the impact body to the surface of the material is 1mm, a reverse induction voltage can be generated. These two voltage ratios may be substituted for the speed ratio. However, this approach has drawbacks. 1. The extreme voltage position is difficult to ensure, and the impact body is just 1mm away from the surface of the material; 2. due to the influence of noise, the voltage extreme value measurement can have deviation; 3. the circuit zero point is not well determined, and deviation also occurs; 4. during measurement, the phenomena of different speeds and the same voltage appear at the wave crest and the wave trough of the voltage, so that the speed measurement is not accurate enough.
In the formula: v. of R The rebound speed of the impact body at a position 1mm away from the surface of the material; v. of I The impact speed of the impact body at a position 1mm away from the surface of the material; u shape R The voltage value induced when the impact body rebounds at a position 1mm away from the surface of the material is obtained; u shape I The voltage value induced when the impact body impacts at a position 1mm away from the surface of the material is obtained; beta is at the 1mm position when the impact body impactsThe angle of inclination of (d); alpha is the inclination angle at the position of 1mm when the impact body rebounds; n is the number of turns of the coil; l is the single turn coil length. The induced voltage is shown in figure 6.
Shore hardness refers to a test and method of expressing the hardness of a material. The test principle is to drop a prescribed diamond punch from a fixed height onto the surface of the sample, the punch rebounds a certain height, and the ratio of the rebounding height to the dropping height is used to calculate the shore hardness. The ratio of the heights is equivalent to the ratio of the energies.
Shore hardness measurement methods currently in common use:
is modified by the formula
T-rebound time, ms;
g-acceleration of gravity, m/s 2 ；
H-initial height of punch drop.
And a piezoelectric sensor made of ceramic material is arranged in the test bed below the Shore hardness tester, and the time of the Shore punch impacting the test bed for the first time and the time of impacting the test bed for the second time after rebounding are measured by the piezoelectric ceramic. The Shore hardness values were obtained by substituting the formula. This method does not measure the energy ratio directly, but indirectly. In particular, for shore hardness measurements of different hardness, the depth of indentation may vary, and thus the measured error, although correctable, is difficult to eliminate as random error. For high accuracy measurements, the uncertainty can be large.
Shore and Rockwell hardness belong to dynamic hardness test methods, shore considers the vertical height of rebound of an impact body, so a Shore hardness tester is used vertically downwards, which causes great limitation in practical use; the Richter study shows that the rebound and impact speeds of an impact body depend on the accuracy of measuring and calculating the speed, and the defect of low measurement accuracy of the Richter hardness and the Shore hardness caused by inaccurate speed detection easily exists.
Disclosure of Invention
Aiming at the technical problems of inconvenient use and low measurement accuracy in the Shore and Shore hardness measurement process in the prior art, the invention provides a method for measuring the Shore and Shore hardness based on double-coil electromagnetic induction,
the method for measuring the hardness of the material to be measured and the hardness of the Shore hardness comprises the steps of placing the material to be measured on a workbench, impacting the lower part of a guide pipe, magnetizing an impact body in the guide pipe, placing two closed coils on the outer wall of the guide pipe, enabling the magnetizing impact body to penetrate through the two closed coils at a certain speed and impact the surface of the material to be measured, recording the time interval when the magnetizing impact body passes through the two closed coils, and calculating the speed of the impact body, so that the hardness of the material to be measured and the hardness of the Shore hardness are obtained;
further, the method for measuring the hardness in Rich comprises the following steps:
step 1-1, placing a material to be tested below a Leeb impact catheter, wherein a magnetized impact body is arranged in the catheter, and two closed coils are sleeved on the outer wall of the catheter; the distance between the central points of the two closed coils is s; when the center of the permanent magnet in the impact body is superposed with the middle positions of the two closed coils, the distance between the ball head at the top end of the impact body and the surface of the material to be measured is 1mm;
step 1-2, the magnetized impact body passes through the two closed coils at a certain speed and impacts the surface of the material to be measured, and the time interval of the magnetized impact body passing through the center positions of the two closed coils is obtained and recorded as t 1 ；
1-3, after the magnetized impact body impacts the surface of the material to be detected, rebounding is generated, the rebounding process penetrates through the two closed coils again, the time interval of the rebounding passing through the center positions of the two closed coils is obtained, and the time interval is recorded as t 2 ；
Step 1-4, calculating according to the formula 1 to obtain the Rich hardness of the object to be measured;
in the formula (1), the reaction solution is,
v R the rebound speed of the impact body at a position 1mm away from the surface of the material;
v I for impacting body in distance materialImpact velocity at 1mm of the material surface;
s is the distance between the center positions of the two closed coils;
t 1 the time interval for the impact to pass through the center positions of the two closed coils;
t 2 the time interval for the rebound to pass through the center positions of the two closed coils;
further, the method for measuring Shore hardness specifically comprises the following steps:
step 2-1, placing a material to be tested below a Shore impact guide pipe, wherein a magnetization impact body is arranged in the guide pipe, and two closed coils are sleeved on the outer wall of the guide pipe; the distance between the central points of the two closed coils is s; when the center of the permanent magnet in the impact body is superposed with the middle positions of the two closed coils, the distance from the ball head at the top end of the impact body to the surface of the material to be measured is h 0 ；
Step 2-2, the magnetized impact body passes through the two closed coils from top to bottom at a certain speed and impacts the surface of the material to be tested;
and 2-3, after the magnetized impact body impacts the surface of the object to be detected, rebounding is generated, the impact body passes through the two closed coils again in the rebounding process, the time interval of the impact body passing through the two closed coils in the rebounding process is obtained, and the time interval is recorded as t 2 ；
Step 2-4, calculating according to the formula 2 to obtain the Shore hardness of the object to be measured;
in the formula (2), the reaction mixture is,
m is the mass of the magnetized impact body;
g is gravity acceleration, g =9.80665 m/s 2 ；
h 0 The height from the center positions of the two closed coils to an object to be measured;
v is the velocity of the magnetized impact body when passing through the two closed coils;
h is the initial height between the magnetized impact body and the object to be measured;
in the formula 2, v is calculated by the formula 3;
in the formula (3), the reaction mixture is,
s is the distance between the central points of the two closed coils;
t 2 the time interval for the impact body to rebound past the center position of the two closed coils.
Furthermore, the magnetized impact body is a moving object and is added with a magnetic material; or magnetizing the impact body;
furthermore, two ends of the closed coil are connected with a signal acquisition circuit;
furthermore, the signal acquisition circuit comprises a voltage signal acquisition device and a time timer;
further, the two closed coils comprise a large coil and a small coil; the large coil is sleeved on the small coil, and the central points of the two coils are very close; or two closed coils with the same diameter are sequentially sleeved on the outer wall of the impact catheter.
Further, the distance S between the central points of the two coils is measured by a vernier caliper or a Doppler laser speed measuring device;
furthermore, the voltage signal collector is a voltage sensor, and the voltage sensor is used for acquiring two zero-value voltage values generated on a signal collecting circuit when the magnetized impact body passes through the two closed coils;
furthermore, the time timer is used for acquiring and recording the interval time between two zero-value voltage values generated on the signal acquisition circuit;
in a specific embodiment of the invention, the magnetized impact body is made of a steel material, and a permanent magnetic material is embedded inside the magnetized impact body;
according to the method for measuring the Rich hardness and the Shore hardness based on the double-coil electromagnetic induction, provided by the invention, the Rich hardness and the Shore hardness of the object to be measured are calculated by adopting the time interval between the zero voltages of two adjacent closed coils with the measuring central points close to each other, measuring the distance between the central points between the adjacent closed coils with the measuring central points close to each other and the distance parameter between the closed coils with the measuring central points close to each other and the object to be measured; by shortening the distance between the central points of the two adjacent closed coils, the error of detection data is greatly reduced, and the accuracy of the calculated hardness in Richter and Shore is high;
according to the method for measuring the hardness of the Shore and the hardness based on the double-coil electromagnetic induction, provided by the invention, in the actual use process, the method is not limited by the existing Shore hardness instrument in the use process, and the applicability is good.
Drawings
FIG. 1 is a graph showing the measurement of the hardness in Rockwell of the metallic Material according to example 1 of the present invention;
FIG. 2 is a schematic view of coil measurement of embodiment 1 of the present invention;
FIG. 3 is a schematic diagram showing the time-dependent changes in induced voltage according to example 1 of the present invention;
FIG. 4 is a schematic view showing Shore hardness measurement of a metal material of example 2 of the present invention; (ii) a
FIG. 5 is a schematic view of a closed coil connection detection module of the present invention;
FIG. 6 is a graph of induced voltage for a prior art hardness measurement;
in the figure:
1. an impact body; 2. an impingement tube; 3. closing the coil; 4. a metal material; 5. a permanent magnet; 8. a timing module; 10. a displacement measurement module; 12. a calculation module; 14. and a display module.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The terms first, second and the like in the description and in the claims and the drawings of the present invention are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged under appropriate circumstances in order to facilitate the description of the embodiments of the invention herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps S or elements is not necessarily limited to those steps S or elements expressly listed, but may include other steps S and elements not expressly listed or inherent to such process, method, article, or apparatus.
In order to make the technical solutions of the present invention better understood, the technical solutions of the present invention are described below clearly and completely in combination with the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art based on the embodiments of the present invention without making creative efforts, shall fall within the protection scope of the present invention.
Example 1 measurement of the hardness in Rich of a metallic Material
As shown in fig. 1, a permanent magnet 5 is embedded in an impact body 1 to obtain a magnetized impact body 1 of the embodiment;
respectively placing the magnetized impact body 1 and the material 4 to be detected on two sides of the two closed coils 3; the two closed coils 3 are two closed coils with the same diameter and are sequentially sleeved on the outer wall of the impact conduit; the distance between the center points of the two closed coils 3 was measured by using a vernier caliper as s =1.6mm; the distance between the middle position of the two closed coils 3 and the metal material 4 is 1mm;
as shown in figure 2 of the drawings, in which,
two ends of the two closed coils 3 are respectively connected with a signal acquisition circuit; the signal acquisition circuit comprises a voltage sensor which measures the voltages U1 and U2 on the connected large and small coils;
the signal acquisition circuit comprises a time timer which is used for acquiring and recording the interval time between two zero-value voltage values generated on the signal acquisition circuit;
the magnetized impact body 1 impacts the surface of the material 4 to be measured after passing through the two closed coils 3 at the speed of about 2m/s, when the magnetized impact body 1 passes through the two closed coils 3, two zero-value voltage values are generated on the signal acquisition circuit, and the voltage sensor measures two times of zero-value voltage U1=0, U2=0; the time timer respectively records time when the zero-value voltage U1=0 and the zero-value voltage U2=0 twice, and obtains the interval time t between the two zero-value voltages 1 ＝0.8ms；
After the magnetized impact body 1 impacts the surface of the object to be detected, rebound is generated, the object to be detected passes through the two closed coils again in the rebound process, two zero-value voltage values during rebound are generated on the signal acquisition circuit again, the time is respectively recorded by the time timer when the zero-value voltage U1=0 and the zero-value voltage U2=0 rebound twice, and the interval time t between the two zero-value voltage values during rebound is obtained 2 ＝0.62ms；
Substituting the obtained measurement value into the following formula 1 to calculate the hardness of the metal material 4 to be measured;
obtaining 775HLD of the hardness of the metal material 4 to be detected;
in the present embodiment, the voltage sensor induced voltage variation is illustrated in fig. 3; the variation curve of the induced voltage U along with the time t is similar to a sine curve;
specifically, in the process that the magnetized impact body 1 enters the induction range of the first closed coil from zero time to the central point of the first closed coil, the induction voltage is increased from zero value and then reduced after reaching a catastrophe point of a peak, and when the magnetized impact body is positioned at t a At the moment, the voltage value is reduced to zero and a time node of the moment is obtained; when the measured object leaves the induction range from the central point, the induction voltage starts to decrease from a zero value and rises to the zero value after passing through a catastrophe point of a trough, and a time node t at the moment is obtained b (ii) a Reaches t after a period of time c At the moment, the measured object enters the induction range of the second closed coil, the change rule of the induction voltage entering the first closed coil is similar to that of the induction voltage entering the second closed coil, the induction voltage is reduced to zero value after passing through a mutation point of a wave crest, and the time node t at the moment is obtained d The induction voltage rises to zero value after passing through a mutation point of a trough, and a time node t at the moment is obtained e Therefore, in the embodiment of the present invention,acquiring a time node signal t of the measured object passing through the central points of the at least two closed coils according to the change rule of the induction voltage a And t d Calculating the time interval t between passing through adjacent closed coils x ：t x ＝t d -t a 。
Example 2 Shore hardness measurement of Metal Material
As shown in figure 4 of the drawings,
respectively placing a magnetized impact body 1 (with the mass of 36.2 g) and a metal material 4 to be detected on the upper side and the lower side of two closed coils 3; the two closed coils 3 comprise a large coil and a small coil, the large coil is sleeved on the small coil, the central points of the two coils are very close, and the distance between the central points of the two closed coils 3 is measured by a vernier caliper laser device to be s =1.6mm; the height between the central position 3 of the two closed coils and the metal material 4 is h 0 =1mm; the initial height H between the magnetized impact body 1 and the metal material 4 to be measured is 19mm;
two ends of the two closed coils 3 are respectively connected with a signal acquisition circuit; the signal acquisition circuit comprises a voltage sensor which measures the voltages U1 and U2 on the connected large and small coils;
the signal acquisition circuit comprises a time timer which is used for acquiring and recording the interval time between two zero-value voltage values generated on the signal acquisition circuit;
the magnetic impact body 1 passes through the two closed coils 3 from top to bottom at a speed of 0.6m/s and then impacts the surface of the metal material 4 to be measured, the magnetic impact body 1 rebounds after impacting the surface of an object to be measured, when the magnetic impact body 1 rebounds from bottom to top and passes through the two closed coils 3, two zero-value voltage values are generated on the signal acquisition circuit, and the voltage sensor measures two times of zero-value voltages U1=0 and U2=0; the time timer respectively records time when zero-value voltages U1=0 and U2=0 are twice, and the time t of the interval between the two zero-value voltages in rebound is obtained 2 ＝66.7ms；
Calculating the velocity v =0.245m/s at closing the coil 3 during the rebound of the magnetized impact body 1 according to equation 3;
substituting the obtained measurement value into the following formula 2 to calculate the Shore hardness of the metal material 4 to be measured;
the shore hardness of the to-be-measured metal material 4 is calculated to be 30HSD;
the measurement procedures of example 1 and example 2 were repeated for 10 times in parallel, and the calculated repetition rate of the hardness in richter was 3HLD and the repetition rate of the hardness in shore was 1.5HSD;
compared with the existing Richter scale hardometer and Shore scale hardometer produced by the company producing the Richter scale hardometer and the Shore scale hardometer in China, the method used by people directly measures the speed value according to the definition of the Richter scale hardness and directly measures the energy value according to the definition of the Shore scale hardness. As shown in comparative example 3:
comparative example 3
The metal material 4 to be measured is subjected to the hardness in Rich region by the existing method shore hardness measurement;
(1) The metal material 4 to be measured is impacted by an impact body with the specified mass of 5.45g and the Rockwell hardness at the speed of 2.05 m/s; then the impact body rebounds after contacting the metal material 4 to be measured, the corresponding rebounding speed is 1.6m/s, the induced voltage value generated in the closed coil by the measured moving magnetic field is used at the position of 1mm on the surface of the metal material 4 to be measured, the induced voltage is respectively 200mV and 156mV when the impact speed and the rebounding speed are respectively 2.05m/s and 1.6m/s through measurement, and then the Richter hardness value is obtained through calculation. Repeating the operation for 10 times;
due to the influence of factors such as noise, 1mm distance, top leveling and the like, the measurement accuracy and the measurement repeatability of the conventional method are (4-8) HLD, and sometimes the measurement repeatability even exceeds 12HLD.
According to the method for measuring the hardness of the steel wire, errors caused by 1mm position, circuit noise and top end leveling are eliminated, and the measurement repeatability and the measurement precision are greatly improved. The measurement accuracy and measurement repeatability will be less than 4HLD.
(2) Shore hardness, the currently used Shore hardness machine, does not measure the maximum energy ratio of the impact and rebound processes, but passes through an approximate formula
HSD＝k×(1/H)×(g/8)×T^2.
The shore hardness values were obtained. 1. The indirect method has errors, which are not derived from the original definition of shore hardness; 2. in the measurement of the time T, because the hardness values of the tested piece are different, the indentation depths of the punch head entering the material are also different, and the corresponding times are also different, when the precision requirement is very high, larger errors can be brought even if the punch head is corrected, and the repeatability of the obtained Shore hardness experimental data is generally 2.5HSD or even higher through actual repeated measurement.
According to the method for measuring the Shore hardness, no matter how different the indentation depths are caused by different hardness values, the side measurement precision cannot be influenced; and the workpiece can be directly measured, because piezoelectric ceramics do not need to be arranged inside the test bed. The measurement error and measurement repeatability do not exceed 1.5HSD. (ii) a
In summary, comparing examples 1 and 2 with comparative example 3, it can be seen that comparative example 3 has a repetition of (4-8) HLD, even exceeding 12HLD, relative to the hardness measurement of the prior art; measurement of shore hardness of contrast 3 repeatability 2.5HSD; the hardness in Richs of the steel in examples 1 and 2 of the present invention the measured hardness in the Shore hardness measuring method has the repeatability of the hardness in the Rockwell hardness which is not higher than 3HLD, the repeatability of Shore hardness is not more than 1.5HSD, which is greatly lower than the repeatability value of the measurement method in the prior art;
<xnotran> , , , , . </xnotran>
In other specific embodiments of the present invention, the magnetizing impact body 1 is a magnetic core inside the impact body for magnetizing;
the magnetic core is a cylinder, the magnetized magnetic core is arranged in a hollow groove at the tail end of the impact body, and when the central position of the magnetic core is coincided with the middle positions of the two closed coils, the distance between the ball head at the front end of the impact body and the surface of the material is 1mm.
In the specific implementation process, the magnetic core is placed in a magnetic field formed by a coil through which direct current passes to carry out magnetizing treatment, wherein the magnetic core is an easily magnetized object such as metal objects of iron, cobalt, nickel and the like.
In other specific embodiments of the present invention, the closed coil is a hollow and closed planar coil surrounded by a conductive wire, and has a shape and a size that enable an impact body to pass through according to a predetermined direction, the closed coil is arranged in parallel, and projections of the central point in the parallel plane are overlapped; a timing module, a calculating module, a displacement measuring module and a display module are connected to the closed coil; as shown in figure 5 of the drawings,
the timing module 8 is connected with the closed coil and used for acquiring a time node of the measured object passing through the center point of the closed coil according to an electromagnetic induction principle; in the embodiment of the invention, the timing module is a time timer;
a displacement measuring module 10 for measuring the distance between adjacent coils of the at least two closed coils;
a calculating module 12, connected to the timing module 8 and the displacement measuring module 10, respectively, for calculating an average speed of the object to be measured passing through between the at least two closed coils;
the display module 14 is respectively connected with the timing module 8, the displacement measurement module 10 and the calculation module 12, and is used for displaying the measurement data and the calculation data;
the displacement measuring module 10 comprises an adjustable guide rail;
the adjustable guide rail is fixedly connected with the two closed coils respectively, so that the two closed coils are kept parallel and can be subjected to axial displacement adjustment, and the distance between the centers of the two closed coils is obtained through the displacement measurement module 10.
Other technical schemes of the invention have similar beneficial effects as described above.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all equivalent structures or equivalent processes performed by the present invention or directly or indirectly applied to other related technical fields will be covered by the scope of the present invention.
Claims (8)
1. A method for measuring the hardness of a hardness meter in Rich and Shore based on double-coil electromagnetic induction is characterized by comprising the following steps:
the method comprises the steps of placing a material to be detected on a workbench, enabling a magnetized impact body to be in a conduit, impacting the surface of the material to be detected after the magnetized impact body passes through two closed coils at a certain speed, recording the time interval when the magnetized impact body passes through the two closed coils, and calculating the speed of the impact body, so that the Richs hardness or the Shore hardness of the material to be detected is obtained.
2. The method for measuring hardness in Rich and Shore based on dual-coil electromagnetic induction according to claim 1,
the magnetization impact body is made of a magnetic material embedded in the impact body.
3. The method for measuring hardness on the basis of double-coil electromagnetic induction according to claim 1,
the two ends of the closed coil are connected with a signal acquisition circuit;
the signal acquisition circuit comprises a voltage signal acquisition device and a time timer.
4. The method for measuring hardness in Rich and Shore based on double-coil electromagnetic induction according to claim 1,
the two closed coils comprise a large coil and a small coil, the large coil is sleeved on the small coil, and the center points of the two coils are very close to each other; or two closed coils with the same diameter are sequentially sleeved on the outer wall of the impact catheter.
And the distance S between the central points of the two coils is measured by adopting a vernier caliper or a Doppler laser speed measuring device.
5. The method for measuring hardness on a Shore/Richch scale based on the double-coil electromagnetic induction as claimed in claim 3,
the voltage signal collector is a voltage sensor, and the voltage sensor is used for acquiring two zero voltage values generated on a signal collecting circuit when the magnetized impact body passes through the two closed coils;
and the time timer is used for acquiring the interval time between two zero-value voltage values generated on the recording signal acquisition circuit.
6. The method for measuring hardness in Rich and Shore based on double-coil electromagnetic induction according to claim 1,
the method for measuring the hardness in Rich region specifically comprises the following steps:
step 1-1, placing a material to be tested below a Richter impact conduit, wherein a magnetized impact body is arranged in the conduit, and two closed coils are sleeved on the outer wall of the conduit; the distance between the central points of the two closed coils is s; when the center of the permanent magnet in the impact body is superposed with the middle positions of the two closed coils, the distance between the ball head at the top end of the impact body and the surface of the material to be measured is 1mm;
step 1-2, the magnetized impact body impacts the surface of the material to be measured after passing through the two closed coils at a certain speed, and the time interval of the magnetized impact body passing through the central positions of the two closed coils is obtained and recorded as t 1 ；
Step 1-3, after the magnetized impact body impacts the surface of the material to be detected, springback is generated, the material passes through the two closed coils again in the springback process, the time interval of the springback passing through the two closed coils is obtained and is recorded as t 2 ；
Step 1-4, calculating according to the formula 1 to obtain the hardness of the object to be measured;
in the formula (1), the reaction solution is,
v R the rebound speed of the impact body at a position 1mm away from the surface of the material;
v I the impact speed of the impact body at a position 1mm away from the surface of the material;
s is the distance between the center positions of the two closed coils;
t 1 the time interval of the impact body passing through the center positions of the two closed coils;
t 2 the time interval for the rebound to pass through the center positions of the two closed coils.
7. The method for measuring hardness on the basis of double-coil electromagnetic induction according to claim 1,
the method for measuring the Shore hardness specifically comprises the following steps of:
step 2-1, placing a material to be tested below a Shore impact guide pipe, wherein a magnetization impact body is arranged in the guide pipe, and two closed coils are sleeved on the outer wall of the guide pipe; the distance between the central points of the two closed coils is s; when the center of the permanent magnet in the impact body is coincided with the middle positions of the two closed coils, the distance between the ball head at the top end of the impact body and the surface of the material to be measured is h 0 ；
Step 2-2, the magnetized impact body impacts the surface of the object to be measured after passing through the two closed coils from top to bottom at a certain speed;
and 2-3, after the magnetized impact body impacts the surface of the object to be detected, rebounding is generated, the rebounding process passes through the two closed coils again, and the time interval of the rebounding passing through the two closed coils is obtained and recorded as t 2 ；
Step 2-4, calculating the Shore hardness of the object to be measured according to the formula 2;
in the formula (2), the reaction mixture is,
m is the mass of the magnetized impact body;
g is gravity acceleration, g =9.80665 m/s 2 ；
h 0 The height from the middle position of the two closed coils to the material to be detected;
v is the velocity of the magnetized impact body when rebounding through the middle position of the two closed coils;
h is the initial height between the magnetized impact body and the object to be measured.
8. The method for measuring hardness in Rich and Shore based on double-coil electromagnetic induction according to claim 7,
in formula 2, v is calculated by formula 3;
in the formula 3, the first step is,
s is the distance between the central points of the two closed coils;
t 2 the time interval for the impact body to rebound past the center position of the two closed coils.
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| CN117782786B (en) * | 2024-02-26 | 2024-05-14 | 福建省计量科学研究院（福建省眼镜质量检验站） | Improved Shore hardness machine |
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| CN202548141U (en) * | 2012-04-25 | 2012-11-21 | 中国石油大学(北京) | Speed detecting device for pipe cleaner |
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| CN117782786B (en) * | 2024-02-26 | 2024-05-14 | 福建省计量科学研究院（福建省眼镜质量检验站） | Improved Shore hardness machine |
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