CN1034692C - Method and apparatus for multi-hole coaxial error measuring - Google Patents

Abstract

The present invention relates to a method for measuring multi-hole coaxial errors and an apparatus thereof. The measurement is carried out under the control of a computer; each measured hole is measured by a corresponding sensor; all sensors for measuring the same coaxial error are installed in the same axis cross section of a rotary axis; the rotary axis rotates for a circle; the actual contour of each measured hole is scanned and measured by the sensors; the center of the least square center circle of each measured hole, and the distance of each hole relevant to a reference are calculated by data obtained by the sensors by the computer; consequently, the coaxial error of each measured hole relative to a reference hole is calculated. The present invention has the characteristics of high automatization degree, high measuring precision, high detecting speed, reliable operation, convenient operation and advanced technique.

Description

Multi-hole coaxial error measuring method and device

The present invention relates to a kind of measuring technique of multi-hole coaxial error, particularly relate to method and device by the measurement multi-hole coaxial error of computer controlled automatic measuring process.

The measurement of multi-hole coaxial error is the important step in the machine industry normally, as in the explosive motor manufacturing, crankshaft hole on the cylinder body, camshaft hole coaxial accuracy are the important technology indexs that guarantees the cylinder body quality, it has bigger influence to the performance of engine, and therefore convenient its coaxiality error of measuring exactly is a gordian technique in the explosive motor manufacturing.Detection for cylinder body crankshaft hole, camshaft hole coaxiality error, always each producer all adopts receiver ga(u)ge method (axle method) to carry out the qualitative detection of qualified (gauge by) and defective (gauge can't pass), for underproof cylinder body, can not determine because that measured hole causes the defective of cylinder body, error size and the direction of measured hole with respect to benchmark can not be provided again, and measuring error is big and can not provide work in-process to adjust lathe and the required data of quality management.

The Chinese utility model patent of patent No. CN86205007U discloses a kind of measurement mechanism of multi-hole coaxial error, the measuring method of the multi-hole coaxial error that this patent disclosed is, measured workpiece is placed on the worktable, the check rod that the displacement detecting probe is housed inserts in the measured hole of measured workpiece, and be positioned in the aligning device at two ends up and down, by manual operations, by adjusting the aligning device at two ends up and down repeatedly, the center of check rod adjusted to measured workpiece datum hole center overlap, rotate check rod again and measure the relative check rod coaxiality error of measured hole, promptly measure the right alignment in measured hole relative datum hole.Go a step further before the relative receiver ga(u)ge method of this patent, but still belong to traditional measuring method, measuring speed is slow, and measuring accuracy depends on operator's operant level and working attitude.

The objective of the invention is to avoid the weak point of prior art, and provide a kind of by the computer controlled automatic measuring process, can determine underproof measured hole rapidly, the error size of measured hole with respect to benchmark and the measuring method and the device of the high multi-hole coaxial error of direction, measuring accuracy and efficient can be provided rapidly again.

The objective of the invention is to realize by following method and apparatus.

Disclosed multi-hole coaxial error measuring method, be by the whole measuring process of computer controlled automatic, measured workpiece direction in accordance with regulations is placed in movably on the worktable, be transplanted on the measuring position and be locked, the rotating shaft that survey sensor is housed is inserted in the measured hole of measured workpiece and the location automatically.The feature that the present invention is different with the prior art measuring method is:

1. measure rotating shaft and be inserted in the measured hole, and be positioned in the measured hole of two ends.

2. rotate and measure rotating shaft, the sensor in each hole of computer controlled measurement carries out the equal angles scanning sample to the hole real profile, measures each hole with respect to rotating shaft radius centered variable quantity.

3. computing machine calculates the least square center in each measured hole cross section with sad converter technique in the quick recurrence richness, with the record center of circle of this center of circle as this cross section, hole.The center of circle of least square circle is calculated by following formula and is determined: $a_k-j{b}_k=\frac{2}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{kn}}(\mathrm{Cos}{\mathrm{\θ}}_n-\mathrm{jSin}{\mathrm{\θ}}_n)$ $=\frac{2}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{kn}}{e}^{-j\frac{2\mathrm{\π}}{N}n}$ $=\frac{2}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{kn}}{w}^n$ $=\frac{2}{N}{x}_k\left(1\right)$ $a_k=\frac{2}{N}{x}_{\mathrm{kR}}\left(1\right)b_k=\frac{2}{N}{x}_{\mathrm{kI}}\left(1\right)$

K=1,2 ..., m, m are the numbers of measured hole.a _kBe a component of degree n n real part of sad conversion in the richness 2/N doubly, b _kBe a component of degree n n imaginary part of sad conversion in the richness 2/N doubly.

With the least square center line of the above-mentioned 3 two ends measured holes that calculated as the benchmark of measuring other each hole, calculate the distance of the least square center of each measured hole, 2 times of coaxiality errors that are measured hole of this distance to benchmark.Be calculated as follows:

Straight-line equation as the measured hole benchmark is: $\frac{X-a_1}{a_m-a_1}=\frac{y-b_1}{b_m-b_1}=\frac{z-z_1}{z_m-z_1}$ The direction number of this straight line is: $\stackrel{\→}{a}=\{\stackrel{\→}{W},\stackrel{\→}{U},\stackrel{\→}{V}\}=\{a_m-a_1,b_m-b_1,z_m-z_1\}$ The formula of the least square center of measured hole profile below the distance of reference line is pressed calculates: $h_i=\left|\underset{W}{\overset{i}{a_i-a_m}}\underset{U}{\overset{j}{b_j-b_m}}\underset{V}{\overset{k}{z_i-z_m}}\right|/\sqrt{W^2+U^2+V^2}$ Coaxiality error calculates by following formula:

fi＝2hi

I=2 in the formula, 3,4 ..., m-1.

5. measure to finish, screen display measured hole least square center is with respect to the eccentric direction synoptic diagram of benchmark, x, and y coordinate figure and coaxiality error value are printed measurement result.

In order to realize purpose of the present invention better, the present invention also can take following technical measures: when the length-diameter ratio of measured hole≤0.5, measure the least square center that calculates a cross section of measured hole, estimate coaxiality error with this center of circle to the distance of benchmark; When the length-diameter ratio of measured hole＞0.5, measure the least square center that calculates two cross sections of measured hole and the center of circle distance to benchmark, estimate coaxiality error with big one of error in two cross sections.Measure the preferably per 10 ° of once sampling of sensor in each hole, the profile in each hole 36 points of sampling altogether.

The present invention has designed the multi-hole coaxial error measurement mechanism of implementing measuring method of the present invention simultaneously, this device comprises the computing machine of automatic control survey process, display device, printing equipment, the rotating shaft of sensor is housed, drive the axially movable drive unit of rotating shaft, drive the motor that rotating shaft is rotated, movably worktable and the angle sender set and the photoelectric sensor that take measurement of an angle, measured workpiece is placed in movably on the worktable, measured hole is to facing toward rotating shaft, each measured hole is by being installed in corresponding sensor measurement in the rotating shaft, motor passes through x, y bidirectional elastic shaft coupling drives rotating shaft and rotates, the angle sender set is placed in the position of rotating synchronously with rotating shaft, photoelectric sensor is placed on the static housing of phase countershaft, rotating shaft, motor and housing are coupled to one, and guide rail moves in the driving lower edge of drive unit.

For goal of the invention is better realized, device of the present invention has also been taked following technical measures:

Each measured hole of measured workpiece is by one or two sensors scanning survey, all sensors are arranged in the same shaft section of rotating shaft, support and rotating shaft that computer CPU plate and sensor circuit board are installed are fixedly installed togather, between rotating shaft and motor.

Measurement mechanism is a vertical structure, and assembling connects all-in-one-piece motor, support and rotating shaft, and being suspended on by the end face floating bearing can be along on the balladeur train of guide rail slip, the balance weight balance that the chain other end that the weight of suspension body by sprocket bearing is hung.

The rotating shaft lower end is a cone structure, rotating shaft is a two supports, the outer conical surface positioning support of bearing holder (housing, cover) is passed through at measured workpiece nose end topmost in the upper end, the lower end is by having the bearing radial location of special construction, and the structure of bearing is to drive locking ball by sliding sleeve to move that to make cylindrical be that the lower bearing sleeve swelling of the conical surface is in the measured hole of lower end.

It is cylinder piston structure that axially movable drive unit is made in the driving rotating shaft, and the sensor that is installed in the rotating shaft is the eddy current sensor of band contact.

Accompanying drawing 1 is the integral layout synoptic diagram of measurement mechanism of the present invention.

Accompanying drawing 2 is location survey schematic diagrams of the present invention.

Accompanying drawing 3 is coaxiality error schematic diagram calculations of the present invention.

Accompanying drawing 4 is that accompanying drawing 3 i measured holes calculate the schematic plan view of determining least square center.

The present invention is described in further detail by embodiment below in conjunction with description of drawings.Embodiment is that the present invention is applied to EQ153 diesel motor cylinder crankshaft hole, the camshaft hole measuring for the coaxiality error device that No. 2 Automobile Factory introduces the technology processing of U.S. Cummins company.Measured workpiece is 6 Cylinder engine cylinder bodies, and tested crankshaft hole, camshaft hole respectively are 7.Measurement mechanism is a vertical structure.Tested cylinder body 12 is lifted on the dolly worktable 13, and the dolly worktable can and be measured station with lifting station and be locked on the track support.The 11st, the rotating shaft of measuring the camshaft hole coaxiality error, the 10th, the rotating shaft of measuring the crankshaft hole coaxiality error.The eddy current sensor 20 of 7 band contacts all is equipped with in each rotating shaft respectively, and all the sensors in each rotating shaft is positioned at same shaft section, and during measurement, each sensor scan is measured corresponding crankshaft hole or camshaft hole.Each rotating shaft is integral with support 17 fixed connections that computer CPU plate, sensor circuit board 16 are housed separately respectively, pass through x more respectively, y bidirectional elastic shaft coupling 15 and drive motor separately 14 connect, motor is placed in the housing 9, constitutes the measurement component of measuring crankshaft hole and camshaft hole coaxiality error respectively.Photoelectric sensor 18 that takes measurement of an angle and angle sender set 19 are separately fixed on housing 9 and the support 17.The measurement component of the measurement component of measurement crankshaft hole and measurement camshaft hole is respectively by being suspended on the same sliding support 6 balance weight 2 balances that chain 4 one ends that the weight of two measurement components is being supported by sprocket wheel 5 are hung at hinge and the end face floating bearing 7 that both direction rotates.Cylinder piston 3 as driving mechanism moves axially up and down by balladeur train 6 drive measurement components, makes the rotating shaft that sensor is housed enter or withdraw from tested crankshaft hole or camshaft hole.The 1st, the frame of measurement mechanism.

During measurement, elder generation vertically upward is placed on the dolly workbench its crankshaft hole, camshaft hole tested cylinder body, tested cylinder body is delivered to make its measured hole to measuring position and locking facing to rotating shaft again.Cylinder piston 3 is under the control of computing machine, the driving measurement component moves down, because the end of rotating shaft is the conical surface, whole measurement component is by being suspended on the balladeur train at hinge and the end face floating bearing that both direction rotates, and the rotating shaft that sensor is housed automatically enters tested crankshaft hole and camshaft hole.Rotating shaft is inserted and is put in place, the conical surface 21 that housing 9 lower ends are 90 ° contacts the location with tested cylinder body crankshaft hole (camshaft hole) topmost, simultaneously rotating shaft bottom end bearing 22 is in swelling is positioned cylinder body crankshaft hole (camshaft hole) bottom, and the structure of bearing 22 is to drive locking ball by sliding sleeve to move that to make cylindrical be that the lower bearing sleeve swelling of the conical surface is in measured hole.Motor starts under the control of computing machine, the drive rotating shaft is returned and is circled, put in place and stop automatically, each sensor scans the profile in a cross section of 1,2,3,4,5,6,7 crankshaft holes of cylinder body, camshaft hole in the rotation, computing machine is according to angle sender set and the per 10 ° of signals that send of photoelectric sensor, 36 measurement data of difference each sensor of acquisition and recording, calculate least square center, calculate 2 times of distance of 2,3,4,5,6 each hole circle heart to 1,7 hole circle heart lines again, be the coaxiality error of measured hole relative datum.Measure in the scanning process, the measured value that shows each each sampled point of hole in crankshaft hole, the camshaft hole on the screen respectively successively, measure the coordinate figure, coordinate signal figure and the coaxiality error value that finish promptly to show each measured hole center of circle relative datum, the data of the measurement result that printer prints is shown and synoptic diagram.

The calculating principle of coaxiality error of the present invention as shown in Figure 3 and Figure 4.If the sampled value of the i hole measured circle of crankshaft hole (or camshaft hole) is Δ r _Ij, i=1,2 ..., 7, j=0,1 ... N-1, N are sampling number, Δ r _IjBe j change in radius amount of i hole measured circle.O among the figure (0,0) is for measuring the centre of gyration, O ¹ _j(a _i, b _i) be least square center, e _iBe offset.According to traditional recommended formula: $a_i=\frac{2}{N}{\mathrm{\Σ}}_{j=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{ij}}\left(\mathrm{Cos}\right(2\mathrm{\πij}/N)$ $b_i=\frac{2}{N}{\mathrm{\Σ}}_{j=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{ij}}\left(\mathrm{Sin}\right(2\mathrm{\πij}/N)$ Can obtain least square center O ' _i(a _i, b _i, z _i).Measuring basis is the common axis in 1,7 hole as requested, i.e. 1,7 crankshaft hole (or camshaft hole) measured hole least square center O ' ₁(a ₁, b ₁, z ₁), O ' ₇(a ₇, b ₇, z ₇) line L.

Each measured hole coaxiality error is each least square center O ' _i(a _i, b _i, z _i) to the twice of the distance of space line L.

fi＝2hi

i＝2，3，4，5，6

Calculate the least square center of each measured hole according to this traditional recommended formula, need to calculate 2N Cos, Sin; 2N time real number multiplies each other; The inferior real number addition of 2 (N-1).If the cross section number is more, sampled data is many, and then speed is slower.The present invention has adopted sad transform method in a kind of quick recurrence richness, and it can calculate a certain component of degree n n separately, makes computing velocity improve 2/3, is applied to ask the derivation of equation of least square center as follows; $a_k-j{b}_k=\frac{2}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{kn}}(\mathrm{Cos}{\mathrm{\θ}}_n-\mathrm{jSin}{\mathrm{\θ}}_n)$ $=\frac{2}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{kn}}{e}^{-j\frac{2\mathrm{\π}}{N}n}$ $=\frac{2}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{kn}}{w}^n$ $=\frac{2}{N}{x}_k\left(1\right)$ $a_k=\frac{2}{N}{x}_{\mathrm{kR}}\left(1\right)b_k=\frac{2}{N}{x}_{\mathrm{kI}}\left(1\right)$

k＝1，2，3，4，5，6，7

By following formula as can be known, a of least square center _kBe exactly a component of degree n n real part of sad conversion in the richness 2/N doubly, b _kBe exactly a component of degree n n imaginary part of sad conversion in the richness 2/N doubly.

After having determined least square center, the formula that calculates coaxiality error is as follows:

O ' ₁(a ₁, b ₁, z ₁), O ' ₇(a ₇, b ₇, z ₇) straight-line equation of line is: $\frac{x-a_1}{a_7-a_1}=\frac{y-b_1}{b_7-b_1}=\frac{z-z_1}{z_7-z_1}$ The direction number of straight line is: $\stackrel{\→}{a}=\{\stackrel{\→}{W},\stackrel{\→}{U},\stackrel{\→}{V}\}=\{a_7-a_1,b_7-b_1,z_7-z_1\}$ So spatial point to the distance of straight line is: $h_i=\left|\underset{W}{\overset{i}{a_i-a_7}}\underset{U}{\overset{j}{b_j-b_7}}\underset{V}{\overset{k}{z_i-z_1}}\right|/\sqrt{W_2^2+U^2+V^2}$

Coaxiality error is:

fi＝2hi

I=2 in the formula, 3,4,5,6.

In the present invention owing to adopted the method for determining measured hole least square center coordinate with the resulting formula of sad conversion in the quick recurrence richness; Each measured hole is self-corresponding with each, has the electric vortex sensor measuring of average effect; The all the sensors of measuring crankshaft hole is installed in respectively in the same shaft section of each axis of rotation with all the sensors of measuring camshaft hole; The rotating shaft positioning support is in tested crankshaft hole, camshaft hole up and down in two stomidiums; The rotating shaft band sensor rotation and each hole real profile is carried out putting in place in one week of scanning survey is stopped automatically; Whole measuring process is by computer-implemented control, data acquisition, calculate the least square center in each hole and the advanced technology measures such as coaxiality error in measured hole relative datum hole, guaranteed high-level efficiency of the present invention, high-acruracy survey, make the present invention just can measure crankshaft hole by the one-step installation cylinder body at 3 minutes, the coaxiality error of camshaft hole, uncertainty of measurement reaches≤level of 2 μ m, display device and printer are along with the carrying out of measuring process, demonstration and printing measured hole center are with respect to the coordinate figure of benchmark, coordinate signal figure and coaxiality error value are for adjustment lathe and factory's quality management in the processing provide reliable foundation.

The present invention also has tested cylinder body installation accuracy and requires low advantage except that having above-mentioned advantage.Because device of the present invention is a vertical structure, the bottom of rotating shaft is a circular conical surface, whole measurement component is by being suspended on the sliding support at hinge and the end face floating bearing that both direction rotates, therefore as long as the roller end cone enters measured hole, whole rotating shaft just can be inserted in the measured hole, carries out high-precision measurement.

It is fast that the present invention has automaticity height, measuring accuracy height, detection speed, easy to operate, reliable, the characteristics of advanced technology, it is the satisfactory technology of measuring multi-hole coaxial error, solved the explosive motor manufacturing and thirsted for for a long time solving and open question, the powerful measure that detects cylinder body crankshaft hole, cam hole coaxiality error is provided for them.

Measuring method of the present invention is not limited to only be suitable for measurement mechanism of the present invention, also can be used for other similar device, measures the coaxiality error of porous.

Measurement mechanism of the present invention also is not limited to the described embodiment of accompanying drawing.

Claims (8)

1, a kind of measuring method of multi-hole coaxial error, measured workpiece direction in accordance with regulations are placed in movably on the worktable, are transplanted on the measuring position and are locked, and the rotating shaft that survey sensor is housed is inserted in the measured hole of measured workpiece, it is characterized in that:

(1) measures rotating shaft and be inserted in the measured hole, and be positioned in the measured hole of two ends;

(2) rotate the measurement rotating shaft, the sensor in each hole of computer controlled measurement carries out the equal angles scanning sample to the real profile in hole, measures each hole with respect to rotating shaft radius centered variable quantity;

(3) computing machine calculates the least square center in each measured hole cross section with sad converter technique in the quick recurrence richness, and with the record center of circle of this center of circle as this cross section, hole, the center of circle of least square circle is calculated by following formula and determined: $a_k-{\mathrm{jb}}_k=\frac{2}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{kn}}(\mathrm{Cos}{\mathrm{\θ}}_n-\mathrm{jSin}{\mathrm{\θ}}_n)$ $=\frac{2}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{kn}}{e}^{-j\frac{2\mathrm{\π}}{N}n}$ $=\frac{2}{N}{\mathrm{\Σ}}_{n=0}^{N-1}\mathrm{\Δ}{r}_{\mathrm{kn}}{w}^n$ $=\frac{2}{N}{x}_k\left(1\right)$ $a_k=\frac{2}{N}{x}_{\mathrm{kR}}\left(1\right)b_k=\frac{2}{N}{x}_{\mathrm{kI}}\left(1\right)$

K=1,2 ..., m, m are the numbers of measured hole, a _kBe a component of degree n n real part of sad conversion in the richness 2/N doubly, b _kBe a component of degree n n imaginary part of sad conversion in the richness 2/N doubly,

(4) the least square center line of the two ends measured hole that is calculated with above-mentioned (3) is as the benchmark of measuring other each measured hole, calculate the distance of the least square center of each measured hole to benchmark, 2 times of coaxiality errors that are measured hole of this distance are calculated as follows:

Straight-line equation as the measured hole benchmark is, $\frac{x-a_1}{a_{\text{m}}-a_1}=\frac{y-b_1}{b_m-b_1}=\frac{z-z_1}{z_m-z_1}$ The direction number of this straight line is, $\stackrel{\→}{a}=\{\stackrel{\→}{W},\stackrel{\→}{U},\stackrel{\→}{V}\}=\{a_m-a_1,b_m-b_1,z_m-z_1\}$ The formula of the least square center of measured hole profile below the distance of reference line is pressed calculates, $h_i=\left|\underset{W}{\overset{i}{a_i-a_m}}\underset{U}{\overset{j}{b_j-b_m}}\underset{V}{\overset{k}{z_i-z_m}}\right|/\sqrt{W^2+U^2+V^2}$

Coaxiality error calculates by following formula,

fi＝2hi

I=2 in the formula, 3,4 ..., m-1.

(5) measure to finish, screen display measured hole least square center is with respect to the eccentric direction synoptic diagram of benchmark, x, and y coordinate figure and coaxiality error value are printed measurement result.

2. multi-hole coaxial error measuring method according to claim 1 is characterized in that, when the length-diameter ratio of measured hole≤0.5, measures the least square center that calculates a cross section of measured hole, estimates coaxiality error with this center of circle to the distance of benchmark; When the length-diameter ratio of measured hole＞0.5, measure the least square center that calculates two cross sections of measured hole and the center of circle distance to benchmark, estimate coaxiality error with big one of error in two cross sections.

3. the measuring method of multi-hole coaxial error according to claim 2 is characterized in that measuring the per 10 ° of once sampling of sensor in each hole, the profile in each hole 36 points of sampling altogether.

4. a kind of multi-hole coaxial error measurement mechanism that designs according to the described multi-hole coaxial error measuring method of claim 1, the computing machine that comprises the automatic control survey process, display device, printing equipment, it is characterized in that also comprising the rotating shaft (10) (11) that sensor (20) are housed, drive the axially movable drive unit of rotating shaft (3), drive the motor (14) that rotating shaft is rotated, movably worktable (13) and angle sender set (19) that takes measurement of an angle and photoelectric sensor (18), measured workpiece (12) is placed in movably on the worktable (13), measured hole is to facing toward rotating shaft (10) (11), each measured hole is by being installed in corresponding sensor (20) measurement in the rotating shaft, motor passes through x, y bidirectional elastic shaft coupling (15) drives rotating shaft and rotates, the angle sender set is placed in the position of rotating synchronously with rotating shaft, photoelectric sensor is placed on the static housing of phase countershaft (9), rotating shaft, motor and housing are coupled to one, move at the driving lower edge of drive unit (3) guide rail (8).

5. measurement mechanism according to claim 4, each measured hole that it is characterized in that measured workpiece is by one or two sensors scanning survey, all sensors is arranged in the same shaft section of rotating shaft, the support (17) that computer CPU plate and sensor circuit board (16) are installed is fixedly installed togather with rotating shaft, between rotating shaft and motor.

6. measurement mechanism according to claim 5, it is characterized in that measurement mechanism is a vertical structure, assembling connects all-in-one-piece motor (14), support (17) and rotating shaft (10) (11), be suspended on along guide rail (8) slidably on the balladeur train (6) balance weight (2) balance that the chain (4) that the weight of suspension body is being supported by sprocket wheel (5) hangs by end face floating bearing (7).

7. according to claim 5 or 6 described measurement mechanisms, it is characterized in that the rotating shaft lower end is the conical surface, rotating shaft is a two supports, last rapids outer conical surface (21) positioning support by bearing holder (housing, cover) is at the measured workpiece nose end in hole topmost, the lower end is by bearing (22) radial location, and its structure is to drive locking ball by sliding sleeve to move that to make cylindrical be that the lower bearing sleeve swelling of the conical surface is in the measured hole of lower end.

8. measurement mechanism according to claim 7, it is characterized in that driving rotating shaft, to make axially movable drive unit be cylinder piston structure, the sensor that is installed in the rotating shaft is the eddy current sensor of band contact.

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