CN107449348A - Inner diameter of cylinder sleeve high-precision large-range self-operated measuring unit and measuring method - Google Patents

Abstract

The invention discloses a high-precision and large-scale automatic measuring device for the inner diameter of a cylinder liner. There are optical shafts and lead screws distributed in parallel between the outer plate and the outer plate. Both the optical axis and the lead screw pass through the L-shaped connector. A transmission shaft is installed in the space formed by the three inner plates. The transmission shaft is connected to the motor, and the transmission shaft The lower end is connected with the driving bevel gear, the driving bevel gear meshes with three driven bevel gears, the driven bevel gear is connected with the lead screw, the lead screw nut and the eddy current sensor are fixedly installed on the L-shaped connector, and installed on the short side There is a magnetic scale reading head for measuring displacement, and a magnetic scale is installed on a three-jaw base. The invention uses a motor to drive the eddy current sensor to move linearly, and the magnetic scale reading head detects the position change in real time, thereby ensuring that the eddy current sensor is always in the best measurement position facing the cylinder liner with different inner diameters, and the inner diameter is calculated by the principle of three-point inner diameter measurement.

Description

High-precision and large-scale automatic measuring device and measuring method for inner diameter of cylinder liner

technical field

The invention relates to a high-precision and large-range automatic measuring device and a measuring method for the inner diameter of a cylinder liner, belonging to the measuring field.

Background technique

The cylinder liner is one of the parts with the worst working environment on the diesel engine, and the accuracy of its inner diameter directly affects key technical indicators such as the service life and fuel economy of the diesel engine. At present, there are many methods for detecting the inner diameter of the cylinder liner at home and abroad, mainly divided into contact measurement and non-contact measurement, and the methods and principles adopted are also different. The inner diameter measurement methods of the cylinder liner mainly include: general measuring tool measurement, special measuring tool measurement, inductive caliper measurement, pneumatic measuring instrument measurement, etc. The operation of measuring the inner diameter of the cylinder liner with a general-purpose measuring tool is simple and convenient, but it can only detect the inner diameter of the shallower position near the mouth of the cylinder liner. Similarly, the measurement of the inductance measuring instrument can only measure the cylinder liner with a shorter depth; The efficiency of the inner diameter of the cylinder liner is higher and the accuracy is guaranteed to a certain extent, but its measurement range is small and the function is single, and it is powerless when it involves cylinder liners of various sizes and specifications; although the measurement accuracy of the pneumatic measuring instrument is high and due to It is a non-contact measurement, thereby protecting the surface of the inner wall of the cylinder liner of the measurement target, but the pneumatic measuring instrument cannot adjust the measurement range, and the measurement cost is high, and the environmental requirements are high.

"A Highly Accurate Cylinder Liner Inner Diameter Rapid Measuring Device" invented by Yang Di and Zhang Lijun, Chinese Invention Patent Application Publication No. CN 106247885 A, improves the inner diameter micrometer measurement environment by adding fiber paper for auxiliary measurement, to a certain extent Effectively improves the repeatability and measurement efficiency of the inner micrometer measurement, but because it is still limited by the measurement efficiency of the inner micrometer and the complexity of the adjustment in the measurement process, the improvement of its measurement efficiency has been greatly restricted, although the efficiency improvement is relatively Obviously, but it still takes a lot of time to adjust the device. "A Laser Inner Diameter Measuring Instrument" invented by Suzhou Lanwang Machine Tool Technology Co., Ltd., Chinese invention patent application publication number CN 106152956 A, adopts high-precision laser measurement, high measurement accuracy and no direct contact, no damage to the workpiece during the measurement process, However, its detection range is small, and it can only measure the cylinder liner within the detection range of the laser measuring instrument, and the higher the accuracy of the laser measuring instrument, the smaller the detection range. When the accuracy is guaranteed, the detection range is further limited. The laser measuring instrument is an optical instrument, which has high requirements on the environment, and its stability and reliability cannot be guaranteed in harsh environments.

Contents of the invention

Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a high-precision and large-scale automatic measurement device and method for the inner diameter of the cylinder liner. The motor drives the eddy current sensor to move linearly, and the magnetic scale reading head detects the position change in real time. , so as to ensure that the eddy current sensor is always in the best measurement position facing the cylinder liner with different inner diameters, and the inner diameter is calculated by the principle of three-point inner diameter measurement.

Technical solution: In order to solve the above technical problems, a high-precision and large-scale automatic measuring device for the inner diameter of the cylinder liner of the present invention includes a three-claw base, that is, a first base, a second base and a third base, and the three-claw base The center of the center is provided with a circular boss, the first base, the second base and the third base are distributed along the circumference of the circular boss, the first base, the second base and the third base are all equipped with an inner plate and an outer plate, Between the inner plate and the outer plate, there is an optical axis and a lead screw distributed in parallel. The lead screw is installed between the outer plate and the inner plate through a bearing. Both the optical axis and the lead screw pass through the L-shaped connector, and the L-shaped connector includes The short side and the long side are vertically distributed. The short side passes through the optical axis and the lead screw. A transmission shaft is installed in the space formed by the three inner plates. The transmission shaft is connected to the motor, and the lower end of the transmission shaft is connected to the driving bevel gear. The bevel gear meshes with three driven bevel gears, the driven bevel gear is connected with the lead screw, the lead screw nut is fixedly installed on the short side, the lead screw nut is sleeved on the lead screw, and the vortex for measuring distance is installed on the long side The current sensor is equipped with a magnetic scale reading head for measuring displacement on the short side, and a magnetic ruler is installed on the three-claw base; the vertical plane for calibration is located at the end of the rectangular platform to be calibrated in the three-claw base.

Preferably, the circumferences of the first base, the second base and the third base are evenly distributed on the circular boss.

Preferably, the lower end of the outer plate is provided with a circular groove, and a tapered roller bearing is installed in the circular groove, and the inner ring of the tapered roller bearing is connected with the lead screw.

Preferably, the driven bevel gear is fixed on the end of the lead screw through a snap ring and a key.

Preferably, the three-claw base is covered with a protective cover.

A method for measuring the above-mentioned high-precision and large-scale automatic measuring device for the inner diameter of the cylinder liner, comprising the following steps:

a. Calibration of the initial position of the eddy current sensor

1) A total of three eddy current sensors are used in this device. The initial position of each eddy current sensor needs to be calibrated. The initial position of the eddy current sensor is the shortest position of the eddy current sensor. Move the eddy current sensor to At the initial position, the read values of the three magnetic scale reading heads are reset to zero at the same time, and then the device is placed in the three-coordinate measuring instrument in the detection posture. The detection posture is the upward posture of the circular boss, because the three eddy current sensors They are located on three rectangular platforms of the three-claw base. The three rectangular platforms are the first base, the second base and the third base. Therefore, the initial position calibration of each eddy current sensor needs to be carried out separately, and three rectangular platforms are selected. A rectangular platform in the platform is defined as K ₁ , and the other two rectangular platforms are defined as K ₂ and K ₃ in a clockwise direction;

2) Calibration of the initial position of the eddy current sensor Select a vertical plane for calibration in the three-coordinate measuring instrument and adjust its relative position relative to the device, where the surface parallel to the detection surface of the eddy current sensor _on the K1 rectangular platform is defined as F ₁ surface, the theoretical connection line between the detection point of the eddy current sensor in the K ₁ rectangular platform and the center of the circular boss in the three-claw base is perpendicular to the F ₁ surface, and the positioning surface in the vertical plane for calibration is closely attached Use a three-coordinate measuring instrument on F ₁ to measure three points on the circumference of the circular boss in the three-jaw base, which are respectively marked as Z ₁₁ (a ₁₁ ,b ₁₁ ), Z ₁₂ (a ₁₂ ,b ₁₂ ), Z ₁₃ (a ₁₃ ,b ₁₃ ), since the three points that are not on the same straight line determine a circle, and then calculate the coordinates of the center of the circular boss in the three-claw base, denoted as O ₁ (a _q1 ,b _q1 ), Use a three-coordinate measuring device to measure two points F ₁ ′, F ₁ ″ distributed horizontally on the calibration surface in the vertical plane for calibration, calculate these two points and O ₁ in the same plane, and do the calculation through O ₁ A straight line perpendicular to the line connecting two points, and then the intersection point of the two straight lines can be calculated as P ₁ (a _p1 , b _p1 ), and the coordinates of point O ₁ and point P ₁ are known, and then calculated according to the formula for the distance between two points in the plane Get the length of O ₁ P ₁ , where the length of O ₁ P ₁ is the distance between the central axis of the circular boss and the vertical plane used for calibration;

3) Start the motor, drive the eddy current sensor to move close to the vertical plane for calibration, until the value read by the eddy current sensor is around the middle of the measurement range of the eddy current sensor, the motor stops, and at this time read the eddy current on the K ₁ rectangular platform The value read by the sensor is recorded as D ₁ , and the reading head value of the magnetic scale on the rectangular platform K ₁ is recorded as B ₁ ; the clamping device in the three-coordinate measuring instrument is driven to make the device rotate around the central axis of the circular boss. Stop after 120°. At this time, the theoretical connection line between the detection point of the eddy current sensor in the K ₂ rectangular platform and the center of the circular boss in the three-claw base is parallel to the normal line of the vertical plane used for calibration, and read the K ₂ rectangular platform The value read by the upper eddy current sensor is recorded as D2, and the value read by the magnetic scale reading head _on the K2 rectangular platform is recorded as B2 _; drive the clamping device in the _three -coordinate measuring instrument to make the device around the central axis of the circular boss Rotate and stop after rotating 120°. At this time, the theoretical connection line between the detection point of the eddy current sensor in the K ₃ rectangular platform and the center of the circular boss in the three-claw base is parallel to the normal line of the vertical plane used for calibration, and read K ₃ The value read by the eddy current sensor on the rectangular platform is recorded as D ₃ , and the value read by the magnetic scale reading head on the K ₃ rectangular platform is recorded as B ₃ ;

4) Note that the initial position of the eddy current sensor in the K ₁ rectangular platform is point Z ₂₁ , and the position of the eddy current sensor when the reading value of the eddy current sensor stops at the middle position of the eddy current sensor measuring range is point Z ₃₁ ; record the K ₂ rectangular platform The initial position of the medium eddy current sensor is point Z ₂₂ , the position of the eddy current sensor when the reading value of the eddy current sensor stops around the middle position of the measuring range of the eddy current sensor is point Z ₃₂ ; record the initial position of the eddy current sensor in the K ₃ rectangular platform as At point Z ₂₃ , when the reading value of the eddy current sensor stops around the middle of the measuring range of the eddy current sensor, the position of the eddy current sensor is point Z ₃₃ , then the length of Z ₂₁ Z ₃₁ is equal to B ₁ , and the length of Z ₃₁ P ₁ is equal to D ₁ ; The length of Z ₂₂ Z ₃₂ is equal to B ₂ , the length of Z ₃₂ P ₁ is equal to D ₂ ; the length of Z ₂₃ Z ₃₃ is equal to B ₃ , and the length of Z ₃₃ P ₁ is equal to D ₃ , thus calculate the initial position of the eddy current sensor in the K ₁ rectangular platform S ₁ is O ₁ Z ₂₁ ; the calculated initial position S ₂ of the eddy current sensor in the K ₂ rectangular platform is O ₁ Z ₂₂ ; the calculated initial position S ₃ of the eddy current sensor in the K ₁ rectangular platform is O ₁ Z ₂₃ , as shown in the following formula:

S ₁ ＝O ₁ Z ₂₁ ＝O ₁ P ₁ -Z ₂₁ Z ₃₁ -Z ₃₁ P ₁

S ₂ ＝O ₁ Z ₂₂ ＝O ₁ P ₁ -Z ₂₂ Z ₃₂ -Z ₃₂ P ₁

S ₃ ＝O ₁ Z ₂₃ ＝O ₁ P ₁ -Z ₂₃ Z ₃₃ -Z ₃₃ P ₁

From this, the initial positions of the eddy current sensors are calibrated as S ₁ , S ₂ , and S ₃ ;

b. Detect the inner diameter of the cylinder liner

When detecting the cylinder liner within the measuring range, adjust the eddy current sensor to return to the initial position through the power mechanism, and then adsorb the adsorption end of the magnetic base to the circular boss at the bottom of the three-claw base, and install the fixed end of the magnetic base On the tool holder, adjust the position of the device through machine tool program control so that it reaches the theoretical axis of the cylinder liner, adjust the position of the eddy current sensor so that the distance from the inner wall of the cylinder liner is within the detection range of the eddy current sensor, and then control the overall device to drop to The height of the inner diameter needs to be measured inside the cylinder liner. Turn on the motor to adjust the position of the eddy current sensor until the degree of the eddy current sensor starts to change and then stop. Measure the inner diameter of the cylinder liner in real time to obtain the readings D ₁ and D of the three eddy current sensors respectively. ₂ , D ₃ and the readings B ₁ , B ₂ , B ₃ of the three magnetic scale read heads;

c. Calculation of inner diameter of cylinder liner

The three intersection points of the theoretical connection line between the detection point of the eddy current sensor in the three rectangular platforms and the center of the circular boss in the three-claw base and the inner wall of the cylinder liner are respectively recorded as points P ₁ , P ₂ , and P ₃ . The center O of the circular boss in the claw base is taken as the origin, the connection line OP ₁ is taken as the X axis, and the straight line passing through the origin perpendicular to the connection line OP ₁ to the right is defined as the Y axis. According to the calibration value of the initial position of the eddy current sensor on each rectangular platform S ₁ , S ₂ , and S ₃ can calculate the lengths OP ₁ , OP ₂ , and OP ₃ from the three light points P ₁ , P ₂ , and P ₃ to the origin. Since the three straight lines of OP ₁ , OP ₂ , and OP ₃ are 120° Evenly distributed and all pass through the origin, and then the coordinates of the three light points P ₁ (a ₁ , b ₁ ), P ₂ (a ₂ , b ₂ ), P ₁ (a ₃ , b ₃ ), where:

a ₁ =OP ₁ , b ₁ =0

Knowing three points on the edge of the circle, the radius of the circle can be calculated, and then the size of the inner diameter of the cylinder liner here can be calculated. With the movement of the overall measuring device, the diameter at different depths can be measured.

Beneficial effect: compared with the prior art, the present invention has the following advantages:

(1) The present invention adopts an adjustable structure to realize precise adjustment of the position of the eddy current sensor, effectively increasing the measurement range of the device, and compared with the measurement device with the same measurement range, it reduces the cost and improves the measurement accuracy.

(2) The present invention uses the eddy current sensor for detection, which can still maintain high measurement accuracy and reliability in harsh environments; at the same time, the eddy current sensor is used in conjunction with the magnetic scale to accurately detect the displacement of the eddy current sensor. Thereby, the measurement accuracy of the present invention is further improved.

Description of drawings

Fig. 1 is a structural schematic diagram of the device of the present invention.

Fig. 2 is a schematic structural view of the device of the present invention after removing the protective cover.

Fig. 3 is a front view of the position adjustment mechanism of the device of the present invention.

Fig. 4 is a schematic diagram of calibration of the initial position of the eddy current sensor in the measurement method of the device of the present invention.

Fig. 5 is a schematic diagram of the calibration method of the initial position of the eddy current sensor in the measurement method of the device of the present invention.

Fig. 6 is a schematic diagram of measuring the cylinder liner by the device of the present invention.

Among them: 1-three-claw base, 2-inner plate, 3-outer plate, 4-motor seat, 5-stepping motor, 6-bevel gear, 7-position adjustment mechanism, 71-L-shaped plate, 72-wire Rod, 721-lead screw nut, 73-optical axis, 731-bearing end cover, 74-eddy current sensor, 75-magnetic scale reading head, 751-magnetic ruler, 76-cylindrical roller bearing, 761-bearing cover, 78-circlip, 79-tapered roller bearing, 8-shield, 9-marking vertical plane.

detailed description

As shown in Figures 1 to 6, a high-precision and large-range automatic measuring device for the inner diameter of a cylinder liner of the present invention includes a three-claw base 1, a position adjustment mechanism 7, a power mechanism, a protective cover 8, an eddy current sensor 74, and a magnetic grid Chi reading head 75, calibration with vertical plane 9.

As shown in Figures 1 and 2, the three-claw base 1 has a three-claw shape, including a first base, a second base and a third base, with a circular boss in the middle, and the circular boss protrudes downward. , where a hexagonal groove is processed on the upper end of the circular boss, so that the three sides of the hexagonal groove are perpendicular to the direction of the three claws, and three rectangular platforms of the same size extend out in three directions equally divided around it. , a square groove is processed at the end of the rectangular platform, the size of the square groove matches the size of the outer plate 3 in the connection position adjustment mechanism 7, and a counterbore is processed from the other side of the bottom of the square groove to connect the adjustment mechanism 7 in a fixed position Each rectangular platform extends a certain distance on the right side to stick the magnetic ruler 751 in the position adjustment mechanism 7, and the central round platform processes two countersunk holes in the direction of the three equally divided claws for the installation position The inner plate 2 of 7 in the adjustment mechanism processes threaded holes on the sides of the three equally divided claws.

As shown in Figure 2, the through holes processed on each rectangular platform of the three-claw base 1 should be distributed at 120° on the circumference, and the three equal claws on the sides of the three-claw base 1 are processed with Threaded holes, a pair of threaded holes are respectively processed at the two ends of the protective cover 8. The protective cover 8 is connected with the threaded holes on the side of the three equally divided claws through threaded holes. In order to make the protective cover 8 fit better with the measuring device, the protective cover 8 is also a three-claw structure

As shown in Figure 3, Figure 4, and Figure 5, the position adjustment mechanism includes a bevel gear 6, an inner plate 2, a tapered roller bearing 79, a cylindrical roller bearing 76, a bearing cover 761, a screw rod 72, and a magnetic scale reader. Head 75, L-shaped plate 71, optical axis 73, linear bearing, outer plate 3, screw nut 721, eddy current sensor 74 and magnetic scale 751. The magnetic scale reading head 75 is a selected displacement detection sensor; the magnetic scale 751 is used in conjunction with the magnetic scale reading head 75 to detect the displacement of the position adjustment mechanism 7; the eddy current sensor 74 is an optional A fixed distance detection sensor; a blind hole is opened at the upper end of the outer plate 3, the diameter of which is consistent with the size of the optical axis 73, and used to install the optical axis 73, and the diameter and depth of the circular groove at the lower end of the outer plate 3 are consistent with the tapered roller bearing 79, For installing the tapered roller bearing 79, the inner ring of the tapered roller bearing 79 is connected with the lead screw 72, and two threaded holes are opened at the bottom, which coincide with the openings at the end of the rectangular platform of the three-claw base 1; the upper end of the inner plate 2 is opened Blind hole, the diameter is consistent with the size of the optical axis 73, the lower end is processed with a stepped hole for installing the cylindrical roller bearing 76, the bottom is processed with a threaded hole, which coincides with the through hole of the three-jaw base 1 round platform, the top is processed with a threaded hole and the bottom threaded hole Corresponding positions; the long end of the L-shaped plate 71 is a horizontal posture, the short end is a vertical posture, and the short end is thicker, wherein the short end is processed with a through hole on the outside, and the size is consistent with the size of the screw nut, and the inside is processed with a through hole, the size Consistent with the size of the linear bearing, two threaded holes are processed on the side of the short end to connect the magnetic scale reading head 75; two threaded holes are processed on the top of the long end to connect the eddy current sensor 74, and the positions of the two threaded holes should ensure that the eddy current sensor 74 The detection end is flush with the top of the long end of the L-shaped plate 71; the optical axis 73 passes through the linear bearing in the inner hole of the L plate, wherein the linear bearing is fixed by two bearing end covers 731, and the two bearing end covers 731 are respectively connected to each other by 4 screws. The L-shaped plate 71 is linked, and the other end of the optical axis 73 is installed in the blind hole at the upper end of the inner plate 2; The part is connected with the bevel gear 6 through a key connection and fixed with a circlip 78, and the cylindrical roller bearing 76 installed on the inner plate 2 is fixed on the inner plate 2 through a bearing end cover 731, wherein the screw 72 nut is passed through Four threaded holes are fixed in the through holes outside the L-shaped plate 71; two threaded holes are opened on the side of the L-shaped plate 71 to connect the magnetic scale reading head 75, and two threaded holes are opened on the top of the L-shaped plate 71 to connect the eddy current sensor74. There are three position adjustment mechanisms 7 installed on the three-claw base 1 .

As shown in Figure 1, described power mechanism comprises stepping motor 5, motor base 4, coupling, transmission shaft, and described stepping motor is a selected standard stepping motor, and stepping motor 5 is installed on motor base 4 Above, a circular groove and four threaded holes are processed on the top of the motor base 4 for fixing the stepping motor 5, while the top of the motor base 4 is corresponding to the position of the threaded hole on the top of the inner plate 2 to open a counterbore for matching with The inner plate 2 is installed and connected, and the lower end of the motor base 4 corresponds to the three-claw base 1 to open the same hexagonal groove, so that the installation of the three inner plates 2 with the edge of the hexagonal groove can be distributed at 120° and perpendicular to the three claws Extending direction: the coupling is a tubular part, the inner wall is processed with a keyway corresponding to the position of the keyway of the stepping motor shaft, and the stepping motor shaft is connected with the transmission shaft through the coupling. The upper part of the transmission shaft has a keyway for connecting with the coupling, and the lower part is a bevel gear 6 structure. The bevel gear 6 on the lower part of the transmission shaft meshes with three bevel gears 6 that are evenly distributed at an angle of 120 degrees, and the three position adjustment mechanisms 7 Transmission power.

In the present invention, the vertical plane 9 for calibration is an L-shaped plate, the long end of which is used for calibration, the inner surface of the long end is the surface for calibration, the short end is used for positioning, and the top surface of the short end is used for positioning. The surface used for positioning is parallel to the surface used for calibration.

Taking the measurement of a cylinder liner with a diameter of 150-360mm as an example to further illustrate the device.

This device is a measurable range device. According to the diameter variation range, the eddy current sensor 74 is selected. The measurement range of the eddy current sensor 74 is 0-10mm, and the measurement range is 10mm. Since the measurement range of the device is continuous, the detection range is 150-360mm.

1. Calibration of the initial position of the eddy current sensor 74

1) Three eddy current sensors 74 are used in this device. The initial position of each eddy current sensor 74 needs to be calibrated. The initial position of the eddy current sensor 74 is the shortest position of the eddy current sensor 74. The read values of the three magnetic scale reading heads 75 are reset to zero, and then the device is placed in the three-coordinate measuring instrument in a detection posture, and the detection posture is the upward posture of the circular boss. Since the three eddy current sensors 74 are located on the three rectangular platforms of the three-claw base, the initial position calibration for each eddy current sensor 74 needs to be carried out separately, and one of the three rectangular platforms is selected to be defined as K ₁ , and thus define the remaining two rectangular platforms as K ₂ and K ₃ in a clockwise direction.

2) Calibration of the initial position of the eddy current sensor 74: select a vertical plane 9 for calibration in the three-coordinate measuring instrument and adjust its relative position relative to the device, wherein the K1 rectangular platform is parallel to the detection surface _of the eddy current sensor 74 _The surface of F1 is defined as F1 surface, the theoretical connection line between the detection point of eddy current sensor 74 in the K1 rectangular platform and the center of the circular boss in the three _- claw base ₁ is perpendicular to F1 surface, and the calibration is performed in the vertical plane 9 The locating surface is closely attached to the F ₁ surface, using a three-coordinate measuring instrument to measure three points on the circumference of the circular boss in the three-jaw base 1, which are respectively marked as Z ₁₁ (a ₁₁ ,b ₁₁ ), Z ₁₂ (a ₁₂ ,b ₁₂ ), Z ₁₃ (a ₁₃ ,b ₁₃ ), since the three points that are not on the same straight line determine a circle, and then calculate the coordinates of the center of the circular boss in the three-claw base 1, denoted as O ₁ (a _q1 , b _q1 ), use a three-coordinate measuring device to measure two points F ₁ ′, F ₁ ″ distributed horizontally on the calibration surface in the vertical plane 9 for calibration, and place these two points on the same plane as O ₁ Carry out the calculation in , pass O ₁ to make a straight line perpendicular to the line connecting these two points, and then calculate the intersection point of the two straight lines as P ₁ (a _p1 ,b _p1 ), the coordinates of point O ₁ and point P ₁ are known, Calculate the length of O ₁ P ₁ according to the distance formula between two points in the plane, where the length of O ₁ P ₁ is the distance between the central axis of the circular boss and the vertical plane 9 for calibration;

3) Start the stepping motor 5 in the power mechanism, and drive the position adjustment mechanism 7 to adjust the eddy current sensor 74 to move in the direction close to the vertical plane 9 for calibration until the eddy current sensor 74 reads a value when the eddy current sensor reads a value of about 5mm , stop the power mechanism. At this time, read the value read by the eddy current sensor 74 on the K ₁ rectangular platform as D ₁ , and read the value of the magnetic scale reading head 75 on the K ₁ rectangular platform as B ₁ ; drive the clamping device in the three-coordinate measuring instrument , so that the entire adjustable cylinder liner inner diameter measuring device can rotate around the central axis of the circular boss, and stop after rotating 120°. At this time, the detection point of the eddy current sensor 74 in the rectangular platform of K ₂ and the distance between the circular boss in the three-claw base 1 The theoretical connection line of the center of the circle is parallel to the normal line of the vertical plane 9 used for calibration, read the value read by the eddy current sensor 74 on the K ₂ rectangular platform and record it as D ₂ , and read the value of the magnetic scale reading head 75 on the K ₂ rectangular platform Denote as B2 _; drive the clamping device in the three-coordinate measuring instrument, so that the entire adjustable cylinder liner inner diameter measuring device can rotate around the central axis of the circular boss, and stop after rotating 120°. _At this time, the eddy current sensor in the K3 rectangular platform The theoretical connection line between the 74 detection points and the center of the circular boss in the three-claw base 1 is parallel to the normal line of the vertical plane 9 for calibration, and the value read by the eddy current sensor 74 on the K ₃ rectangular platform is recorded as D ₃ , read the value of the magnetic scale reading head 75 on the K ₃ rectangular platform and denote it as B ₃ .

4) Note that the initial position _of the eddy current sensor 74 in the K1 rectangular platform is point _Z21 , and the position of the eddy current sensor 74 when the reading value of the eddy current sensor 74 stops at about 5mm is point _{Z31 ;} record the eddy current in the K2 rectangular platform The initial position of sensor 74 is point Z ₂₂ , and when the value read by eddy current sensor 74 stops at about 5 mm, the position of eddy current sensor 74 is point Z ₃₂ ; the initial position of eddy current sensor 74 in K ₃ rectangular platform is point Z ₂₃ , When the value read by the current sensor 74 stops at about 5 mm, the position of the eddy current sensor 74 is point Z ₃₃ . Then the length of Z ₂₁ Z ₃₁ is equal to B ₁ , the length of Z ₃₁ P ₁ is equal to D ₁ ; the length of Z ₂₂ Z ₃₂ is equal to B ₂ , the length of Z ₃₂ P ₁ is equal to D ₂ ; the length of Z ₂₃ Z ₃₃ is equal to B ₃ , and the length of Z ₃₃ P ₁ The length is equal to D ₃ . From this, the initial position S ₁ of the eddy current sensor 74 in the K ₁ rectangular platform can be calculated, which is O ₁ Z ₂₁ ; the initial position S ₂ of the eddy current sensor 74 in the K ₂ rectangular platform can be calculated, which is O ₁ Z ₂₂ ; The initial position S ₃ of the eddy current sensor 74 in the K ₁ rectangular platform can be calculated, which is O ₁ Z ₂₃ , as shown in the following formula:

S ₁ ＝O ₁ Z ₂₁ ＝O ₁ P ₁ -Z ₂₁ Z ₃₁ -Z ₃₁ P ₁

S ₂ ＝O ₁ Z ₂₂ ＝O ₁ P ₁ -Z ₂₂ Z ₃₂ -Z ₃₂ P ₁

S ₃ ＝O ₁ Z ₂₃ ＝O ₁ P ₁ -Z ₂₃ Z ₃₃ -Z ₃₃ P ₁

Accordingly, the initial positions of the eddy current sensor 74 are calibrated as S ₁ , S ₂ , and S ₃ .

2. Detect the inner diameter of the cylinder liner

When detecting the cylinder liner within the measuring range, the eddy current sensor 74 is adjusted back to the initial position through the power mechanism, and then the adsorption end of the magnetic base is adsorbed to the circular boss at the bottom of the three-claw base, and the fixed end of the magnetic base is Install it on the tool holder, adjust the position of the device through machine tool program control, so that it reaches the theoretical axis of the cylinder liner, adjust the position of the eddy current sensor 74 so that the distance between the eddy current sensor and the inner wall of the cylinder liner is within the detection range of the eddy current sensor 0 ~ 10mm, and then Control the overall device to descend to the inside of the cylinder liner to measure the height of the inner diameter, turn on the power mechanism and adjust the position of the eddy current sensor 74 until the reading of the eddy current sensor 74 starts to change and stop, measure the inner diameter of the cylinder liner in real time, and obtain three eddy current sensors respectively The readings D ₁ , D ₂ , D ₃ of 74 and the readings B ₁ , B ₂ , B ₃ of the three magnetic scale read heads 75;

3. Calculate the inner diameter of the cylinder liner

The three intersection points of the theoretical connection line between the detection point of the eddy current sensor 74 in the three rectangular platforms and the center of the circular boss in the three-claw base 1 and the inner wall of the cylinder liner are respectively recorded as points P ₁ , P ₂ , and P ₃ , The center O of the circular boss in the three-claw base 1 is taken as the origin, the line connecting OP ₁ is taken as the X axis, and the straight line passing through the origin perpendicular to the line connecting OP ₁ to the right is defined as the Y axis. According to the eddy current sensor 74 of each rectangular platform The initial position calibration values S ₁ , S ₂ , and _{S 3} can calculate the _lengths OP ₁ , OP ₂ , and OP ₃ from the _three light points P ₁ , P ₂ , and P ₃ to the origin. The straight lines are uniformly distributed at 120° and all pass through the origin, and then the coordinate values of the three light points P ₁ (a ₁ , b ₁ ), P ₂ (a ₂ , b ₂ ), P ₁ (a ₃ , b ₃ ),in:

a ₁ =OP ₁ , b ₁ =0

Knowing three points on the edge of the circle, the radius of the circle can be calculated, and then the size of the inner diameter of the cylinder liner here can be calculated. With the movement of the overall measuring device, the diameter at different depths can be measured. The runout of the bore of the cylinder liner at this height can be measured by rotating the tool holder about the theoretical axis of the cylinder while maintaining the height of the tool holder.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (6)

1. A high-precision and large-scale automatic measuring device for the inner diameter of a cylinder liner, characterized in that it includes a three-claw base, that is, a first base, a second base and a third base, and a circular base is arranged in the center of the three-claw base. The boss, the first base, the second base and the third base are distributed along the circumference of the circular boss, and the first base, the second base and the third base are all equipped with an inner plate and an outer plate, and the inner plate and the outer plate There is an optical axis and a lead screw distributed in parallel between them. The lead screw is installed between the outer plate and the inner plate through a bearing. Both the optical axis and the lead screw pass through the L-shaped connector. The L-shaped connector includes vertically distributed short sides and The long side and the short side pass through the optical axis and the lead screw. A transmission shaft is installed in the space formed by the three inner plates. The transmission shaft is connected to the motor. The lower end of the transmission shaft is connected to the driving bevel gear. The movable bevel gear meshes, the driven bevel gear is connected with the lead screw, the lead screw nut is fixedly installed on the short side, and the lead screw nut is set on the lead screw, the eddy current sensor for measuring the distance is installed on the long side, and the short side A magnetic scale reading head for measuring displacement is installed on the top, and a magnetic scale is installed on the three-claw base. 2. The cylinder liner inner diameter automatic measuring device with high precision and wide range according to claim 1, characterized in that: the circumference of the first base, the second base and the third base are evenly distributed on the circular boss. 3. The cylinder liner inner diameter automatic measuring device with high precision and large range according to claim 1, characterized in that: the lower end of the outer plate is provided with a circular groove, and a tapered roller bearing is installed in the circular groove, and the cone The inner ring of the roller bearing is connected with the lead screw. 4. The cylinder liner inner diameter automatic measuring device with high precision and wide range according to claim 1, characterized in that: the driven bevel gear is fixed at the end of the lead screw by a circlip and a key. 5. The cylinder liner inner diameter automatic measuring device with high precision and large range according to claim 1, characterized in that: the three-claw base is covered with a protective cover. 6. A measuring method of a cylinder liner inner diameter high-precision large-scale automatic measuring device as claimed in any one of claims 1 to 5, characterized in that, comprising the following steps: a. Calibration of the initial position of the eddy current sensor 1) A total of three eddy current sensors are used in this device. The initial position of each eddy current sensor needs to be calibrated. The initial position of the eddy current sensor is the shortest position of the eddy current sensor. Move the eddy current sensor to At the initial position, the read values of the three magnetic scale reading heads are reset to zero at the same time, and then the device is placed in the three-coordinate measuring instrument in the detection posture. The detection posture is the upward posture of the circular boss, because the three eddy current sensors They are located on three rectangular platforms of the three-claw base, the three rectangular platforms are the first base, the second base and the third base, and one of the three rectangular platforms is selected as K ₁ , and thus clockwise The direction defines the remaining two rectangular platforms as K ₂ and K ₃ in turn; 2) Calibration of the initial position of the eddy current sensor: select a vertical plane for calibration in the three-coordinate measuring instrument and adjust its relative position relative to the device, where the surface parallel to the detection surface of the eddy current detection head _on the K1 rectangular platform Defined as the F1 surface, the theoretical connection line between the detection point _of the eddy current sensor in the K1 rectangular platform and the center _of the circular boss in the three _- claw base is perpendicular to the F1 surface, and the positioning surface in the vertical plane for calibration is closely Attached to the F ₁ surface, use a three-coordinate measuring instrument to measure three points on the circumference of the circular boss in the three-jaw base, which are respectively marked as Z ₁₁ (a ₁₁ ,b ₁₁ ), Z ₁₂ (a ₁₂ ,b ₁₂ ), Z ₁₃ (a ₁₃ ,b ₁₃ ), since the three points not on the same straight line determine a circle, and then calculate the coordinates of the center of the circular boss in the three-claw base, which is recorded as O ₁ (a _q1 ,b _q1 ), using a three-coordinate measuring device to measure two points F ₁ ′, F ₁ ″ distributed horizontally _on the calibration surface in the vertical plane for calibration, and calculate these two points and O ₁ in the same plane, and do A straight line perpendicular to the line connecting these two points, and then the intersection point of the two straight lines can be calculated as P ₁ (a _p1 ,b _p1 ), and the coordinates of point O ₁ and point P ₁ are known, according to the distance formula between two points in the plane Then calculate the length of O ₁ P ₁ , where the length of O ₁ P ₁ is the distance between the central axis of the circular boss and the vertical plane for calibration; 3) Start the motor, drive the eddy current sensor to move close to the vertical plane for calibration, until the value read by the eddy current sensor is around the middle of the measurement range of the eddy current sensor, the motor stops, and at this time read the eddy current on the K ₁ rectangular platform The value read by the sensor is recorded as D ₁ , and the value read by the magnetic scale reading head on the K ₁ rectangular platform is recorded as B ₁ ; drive the clamping device in the three-coordinate measuring instrument to make the device rotate around the central axis of the circular boss, and rotate Stop after 120°. At this time, the theoretical connection line between the detection point of the eddy current sensor in the K ₂ rectangular platform and the center of the circular boss in the three-claw base is parallel to the normal line of the vertical plane used for calibration, and read the K ₂ rectangular platform The value read by the upper eddy current sensor is recorded as D2, and the value read by the magnetic scale reading head _on the K2 rectangular platform is recorded as B2 _; drive the clamping device in the _three -coordinate measuring instrument to make the device around the central axis of the circular boss Rotate and stop after rotating 120°. At this time, the theoretical connection line between the detection point of the eddy current sensor in the K ₃ rectangular platform and the center of the circular boss in the three-claw base is parallel to the normal line of the vertical plane used for calibration, and read K _3. The value read by the eddy current sensor on the rectangular platform is recorded as D ₃ , and the value read by the magnetic scale reading head on the K ₃ rectangular platform is recorded as B ₃ ; 4) Note that the initial position of the eddy current sensor in the K ₁ rectangular platform is point Z ₂₁ , and the position of the eddy current sensor when the reading value of the eddy current sensor stops at the middle position of the eddy current sensor measuring range is point Z ₃₁ ; record the K ₂ rectangular platform The initial position of the medium eddy current sensor is point Z ₂₂ , the position of the eddy current sensor when the reading value of the eddy current sensor stops around the middle position of the measuring range of the eddy current sensor is point Z ₃₂ ; record the initial position of the eddy current sensor in the K ₃ rectangular platform as At point Z ₂₃ , when the reading value of the eddy current sensor stops around the middle of the measuring range of the eddy current sensor, the position of the eddy current sensor is point Z ₃₃ , then the length of Z ₂₁ Z ₃₁ is equal to B ₁ , and the length of Z ₃₁ P ₁ is equal to D ₁ ; The length of Z ₂₂ Z ₃₂ is equal to B ₂ , the length of Z ₃₂ P ₁ is equal to D ₂ ; the length of Z ₂₃ Z ₃₃ is equal to B ₃ , and the length of Z ₃₃ P ₁ is equal to D ₃ , thus calculate the initial position of the eddy current sensor in the K ₁ rectangular platform S ₁ is O ₁ Z ₂₁ ; the calculated initial position S ₂ of the eddy current sensor in the K ₂ rectangular platform is O ₁ Z ₂₂ ; the calculated initial position S ₃ of the eddy current sensor in the K ₁ rectangular platform is O ₁ Z ₂₃ , as shown in the following formula: S ₁ ＝O ₁ Z ₂₁ ＝O ₁ P ₁ -Z ₂₁ Z ₃₁ -Z ₃₁ P ₁ S ₂ ＝O ₁ Z ₂₂ ＝O ₁ P ₁ -Z ₂₂ Z ₃₂ -Z ₃₂ P ₁ S ₃ ＝O ₁ Z ₂₃ ＝O ₁ P ₁ -Z ₂₃ Z ₃₃ -Z ₃₃ P ₁ From this, the initial positions of the eddy current sensors are calibrated as S ₁ , S ₂ , and S ₃ ; b. Detect the inner diameter of the cylinder liner When detecting the cylinder liner within the measuring range, adjust the eddy current sensor to return to the initial position through the power mechanism, and then adsorb the adsorption end of the magnetic base to the circular boss at the bottom of the three-claw base, and install the fixed end of the magnetic base On the tool holder, adjust the position of the device through machine tool program control so that it reaches the theoretical axis of the cylinder liner, adjust the position of the eddy current sensor so that the distance from the inner wall of the cylinder liner is within the detection range of the eddy current sensor, and then control the overall device to drop to The height of the inner diameter needs to be measured inside the cylinder liner. Turn on the motor to adjust the position of the eddy current sensor until the degree of the eddy current sensor starts to change and then stop. Measure the inner diameter of the cylinder liner in real time to obtain the readings D ₁ and D of the three eddy current sensors respectively. ₂ , D ₃ and the readings B ₁ , B ₂ , B ₃ of the three magnetic scale read heads; c. Calculation of inner diameter of cylinder liner The three intersection points of the theoretical connection line between the detection point of the eddy current sensor in the three rectangular platforms and the center of the circular boss in the three-claw base and the inner wall of the cylinder liner are respectively recorded as points P ₁ , P ₂ , and P ₃ . The center O of the circular boss in the claw base is taken as the origin, the connection line OP ₁ is taken as the X axis, and the straight line passing through the origin perpendicular to the connection line OP ₁ to the right is defined as the Y axis. According to the calibration value of the initial position of the eddy current sensor on each rectangular platform S ₁ , S ₂ , and S ₃ can calculate the lengths OP ₁ , OP ₂ , and OP ₃ from the three light points P ₁ , P ₂ , and P ₃ to the origin. Since the three straight lines of OP ₁ , OP ₂ , and OP ₃ are 120° Evenly distributed and all pass through the origin, and then the coordinates of the three light points P ₁ (a ₁ , b ₁ ), P ₂ (a ₂ , b ₂ ), P ₁ (a ₃ , b ₃ ), where: a ₁ =OP ₁ , b ₁ =0 Knowing three points on the edge of the circle, the radius of the circle can be calculated, and then the size of the inner diameter of the cylinder liner here can be calculated. With the movement of the overall measuring device, the diameter at different depths can be measured.