CN108050957B - Device and method for measuring shape error of lip curved surface of wave-shaped lip oil seal - Google Patents
Device and method for measuring shape error of lip curved surface of wave-shaped lip oil seal Download PDFInfo
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- CN108050957B CN108050957B CN201810032803.3A CN201810032803A CN108050957B CN 108050957 B CN108050957 B CN 108050957B CN 201810032803 A CN201810032803 A CN 201810032803A CN 108050957 B CN108050957 B CN 108050957B
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Abstract
The invention relates to a measuring device and a measuring method for a waveform lip oil seal lip curved surface shape error, wherein the measuring device comprises a positioning and measuring adjusting device, a camera adjusting device, a measuring device and a computer; the measuring device comprises a longitudinal laser range finder, a transverse laser range finder, a target, a measuring rod, a measuring head, an upper microspur camera, a point laser source and a lower microspur camera, and the curved surface shape error evaluation is carried out on the curved surface shape of the oil seal lip and the curved surface of the standard lip under the same coordinate system by subsequently obtaining the curved surface shape of the oil seal lip through the measuring device. Compared with the traditional contact measurement methods such as a probe measuring head and the like, the measuring device adopts non-contact measurement, does not apply external force to the oil seal of the soft material to cause deformation of the oil seal, and effectively ensures the measurement precision. The measuring device and the measuring method solve the problem that the existing measuring device is difficult to accurately measure the shape error of the lip curved surface of the wave-shaped lip oil seal, can effectively detect the manufacturing precision of the wave-shaped lip oil seal, and ensure the working performance of the oil seal.
Description
Technical Field
The invention relates to a device and a method for measuring the shape error of a lip curved surface of a wave-shaped lip oil seal, and belongs to the technical field of wave-shaped lip oil seals.
Background
The sealing technology is one of the key technologies for realizing modern transmission and control. Although the sealing part is often a small part in the equipment, the cost of the sealing part is negligible relative to that of the whole equipment, but the failure rate is very high, and the sealing part plays a crucial role in the safety of the equipment. Many major safety accidents at home and abroad, such as the loss of a space shuttle of the United states 'challenger' in 1986 and the explosion of the double benzene works of the petroleum Jilin petrochemical division company in 2005, are caused by the failure of a sealing element.
The oil seal is the most structurally complex and widely used rubber component of the rotary seal, and is one of the most commonly used seals. The most commonly used oil seals at present are hydrodynamic oil seals with a "pumping effect", including both return-line seals and wave-lip seals. Compared with a backflow line oil seal, the lip of the wave-shaped lip oil seal is in wave-shaped contact with the rotating shaft, and the oil pump has good oil pumping performance, so that the sealing performance is better, the service life is longer, and the oil pump is suitable for bidirectional rotation.
The lip curved surface structure of the wave-shaped lip oil seal is a key index influencing the sealing performance of the wave-shaped lip oil seal. In order to ensure the working performance of the oil seal, the manufacturing precision of the oil seal, particularly the shape error of the lip curved surface, needs to be detected in the production process of the oil seal.
The main lip of the wave-shaped lip oil seal is complex in structure and is composed of a wave-shaped complex curved surface, so that the manufacturing is difficult, and the manufacturing precision is difficult to detect. At present, special instruments and equipment for detecting the shape error of the lip curved surface of the wave-shaped lip oil seal and an effective method are not available. The existing instruments for measuring the shape error or the profile tolerance of the curved surface of a part are mainly used for contact measurement of the outer surface of a cylindrical part or the inner surface of a cylindrical part. The selection of the measuring object is relatively fixed and needs to be a relatively flat cylindrical surface; with the lip curved surface of the wave lip oil seal mentioned in the present invention, the gauge head of the above measuring instrument is limited in size to make it difficult to perform effective measurement. In addition, the measuring head or the probe in the measuring method inevitably scratches the surface of the measured piece or causes the deformation of the measured piece to influence the measuring precision in the measuring process. The material of the wave-shaped lip oil seal is mostly rubber, and the contact is easy to deform, so that larger measurement errors can be caused.
In addition, although the conventional documents use non-contact laser or photographic instruments for measuring curved surface contours or errors, most of the instruments have complicated structures, require many preliminary preparation works, and are complicated and time-consuming in measurement. The instruments are large in size, are mostly used for measuring large curved surfaces, are limited in measurement accuracy, and are difficult to effectively measure parts with small diameters and high measurement accuracy requirements, such as the wave-shaped lip oil seal.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a device for measuring the shape error of the curved surface of a lip of a wave-shaped lip oil seal.
The invention also provides a measuring method using the measuring device for the waveform lip oil seal lip curved surface shape error.
The technical scheme of the invention is as follows:
the utility model provides a wave form lip oil blanket lip curved surface shape error measuring device, includes location and measures adjusting device, camera adjusting device, measuring device and computer:
the positioning and measuring adjusting device comprises a working platform, an angle index plate supporting platform and an angle index indicator are arranged on the working platform, and an angle index plate and a working circular table are concentrically arranged on the angle index plate supporting platform;
the camera adjusting device comprises a threaded upright post, a lifting support and a telescopic cross frame, the threaded upright post is arranged at the middle point of the side edge of the working platform, guide posts are symmetrically arranged on two sides of the threaded upright post, the lifting support is in threaded connection with the threaded upright post, guide sleeves are arranged on two sides of the lifting support and are installed on the guide posts, and the tail end of the telescopic cross frame is connected to the top end of the lifting support;
the measuring device comprises a longitudinal laser range finder, a transverse laser range finder, a target, a measuring rod, a measuring head, an upper microspur camera, a point laser source and a lower microspur camera, wherein the transverse laser range finder and the longitudinal laser range finder are arranged on a lifting support and are respectively positioned on the upper side and the lower side of a telescopic cross frame;
wherein, angle graduation indicator, vertical laser range finder, horizontal laser range finder, go up the microspur camera, down the microspur camera is connected with the computer respectively.
Preferably, a moving slide rail is installed on the working circular table in the radius direction, a right-angle positioning block is arranged on the moving slide rail, the right-angle positioning block is driven by a linear motor to translate along the moving slide rail, and the linear motor is further connected with a computer. The design has the advantages that the right-angle positioning block is utilized, the oil seal can be conveniently displaced to the position which is on the same vertical line with the circle center of the working circular truncated cone, the accuracy of coincidence of the center of the oil seal and the circle center of the working circular truncated cone can be improved, and the precision of subsequent measurement is guaranteed.
Preferably, the bottom end of the threaded upright post is provided with an upright post knob, and the guide sleeve is provided with a positioning nut. The advantage of this design lies in, through adjusting the stand rotation, can make the screw thread stand rotate very conveniently, and the screw thread stand drives lifting support at the pivoted in-process and realizes reciprocating with the help of the guide pillar, and follow-up fastening through set nut can make lifting support firmly fix in a certain position.
Preferably, the tail end of the telescopic cross frame is provided with a telescopic cross frame knob. The advantage of this design lies in, through twisting the terminal flexible crossbearer knob, can effectively adjust the length of flexible crossbearer.
Preferably, the working platform is rectangular, and the angle index plate support table, the angle index plate and the working circular table are circular; the centers of the working circular table, the angle index plate supporting table and the working platform are on the same vertical line.
A measuring method of a waveform lip oil seal lip curved surface shape error measuring device comprises the following steps:
(1) firstly, setting a fixed coordinate system, setting an original point O of the fixed coordinate system at the circle center of a working circular platform, wherein an X axis is parallel to the wide side of a rectangular working platform, a Y axis is parallel to the long side of the rectangular working platform, and a Z axis is determined according to a right-hand rule;
then an oil seal is placed on the working circular table, and the center of the oil seal is coincided with the circle center of the working circular table by means of a right-angle positioning block;
(2) the position of the lower microspur camera is taken as a reference, the lifting support is adjusted by observing the amplified images shot by the upper microspur camera and the lower microspur camera, and finally point laser is irradiated on a first main lip curve L of the oil sealPForming a measuring point P; then adjusting the length of the telescopic cross frame to control the distance between the upper and lower macro cameras and the surface of the inner ring of the oil seal, so that an image formed on a computer is the clearest; recording the reading L of the transverse laser range finder at the moment after the adjustment is finished1PAnd reading L of longitudinal laser range finder2PThe lower microspur camera takes a photo APTaking a picture B by an upper macro cameraPAt this time, the macro-shot is performedThe position coordinate of the center of the image head in the fixed coordinate system is (X)sP，YsP，ZsP)；
Then point laser is respectively irradiated on a second lip curve L by adjusting the lifting supportMAnd a third lip curve LNThe number of readings of the transverse laser range finder is L at the positions of the two measuring points M and N1MAnd L1NThe readings of the longitudinal laser range finder are L respectively2MAnd L2NThe lower macro camera takes a photo A respectivelyMAnd ANThe upper macro camera takes a picture B respectivelyMAnd BNThe position coordinates corresponding to the lower macro cameras are respectively (X)sM，YsM，ZsM) And (X)sN，YsN，ZsN)；
By using the method, the position coordinate values corresponding to the macro cameras at different measuring points are determined by the following formula:
in the formula: i represents different measuring points when P, M or N is taken respectively; c1The distance from the center line of the threaded upright column to the center of the transverse laser range finder is obtained; c2The distance from the central line of the threaded upright post to the origin O of the fixed coordinate system; c3The distance from the origin O of the fixed coordinate system to the plane of the working platform; c4The distance from the center of the lower macro camera to the center of the longitudinal laser range finder;
the distance between the upper macro camera and the lower macro camera in the Z-axis direction is T, and the position coordinate of the upper macro camera is (X) on the premise that the position coordinate of the lower macro camera is determinedsi,Ysi,Zsi+T)；
(3) Single measurement position photo data processing, photo A taken by following macro camerai(i represents different measuring points when P, M or N are taken respectively) and a picture B taken by a macro camerai(i represents different measuring points when P, M or N is taken respectively) are processed according to the same method; byThe pixel-based image points in the photo are constructed by pixel image coordinate system { o, u, v } and millimeter-based physical image coordinate system { o1X, z }; wherein the origin o of the image coordinate system in pixel units is located at the lower left corner of the photograph, the u-axis is horizontally to the right, the v-axis is vertically upward, wherein the origin o of the physical image coordinate system1Located at a pixel coordinate of (u)0，v0) The x axis is horizontally towards the right, the z axis is vertically towards the upper, and the conversion relation between the two image coordinates is shown as the following formula:
in the formula: k multiplied by l is the size of a pixel point, and k and l are millimeters and belong to internal parameters of a macro camera;
known photograph APThe pixel coordinate of the middle measurement point P is (u)p，vp) Converted to the physical image coordinate system { o } by equation (II)1And the coordinate value under x, z is (x)p，zp) The coordinates of the corresponding measuring points in the other photos in the physical image coordinate system can also be obtained by the formula (II);
to further convert the coordinates of the measurement points into the camera coordinate system, a lower camera coordinate system { O } is establishedx1,Xx1,Yx1,Zx1}: origin Ox1At the center of the lower macro camera, Xx1Axis and Zx1The axes being parallel to the x-and z-axes, respectively, Yx1The axis is vertically intersected with the image plane, and the intersection point is the origin of the physical image coordinate system; simultaneously establishing an upper camera coordinate system (O)x2,Xx2,Yx2,Zx2}: origin Ox2At the center of the upper macro camera, Xx2Axis and Zx2The axes being parallel to the x-and z-axes, respectively, Yx2The axis is perpendicularly intersected with the image plane, and the intersection point is the picture BiThe origin of the physical image coordinate system;
coordinate Y of measuring point in lower camera coordinate systemx1iThe binocular vision distance measurement principle is obtained by the following formula:
in the formula: f is the focal length of the macro camera and belongs to the internal parameters of the camera; | zAiI and I zBiI is the measurement point in photograph AiAnd photograph Bi(i represents different measuring points when P, M or N is taken respectively) the absolute value of the z coordinate in the physical image coordinate system;
coordinate value X of any measuring point in lower camera coordinate system at single indexing positionx1iAnd Zx1iThe value can be obtained by back-calculation from:
in the formula: when the i is respectively P, M or N, the measuring points with different indexing positions are represented;
after the calculation is completed, the coordinates of any measuring point in the lower camera coordinate system can be expressed as (X)x1i,Yx1i,Zx1i)；
(4) After the operation is finished, the surface of the inner ring of the oil seal is subjected to indexing measurement along the circumferential direction, and the coordinates of all measurement points are calculated, wherein the indexing angle is
(the value range is 5-10 degrees), then correspondingly have
Obtaining n measuring positions by indexing positions, wherein the default initial measuring position is the 0 th indexing position; the oil seal is driven to rotate by the working circular table to realize the photographing measurement of each indexing position, and after all the measurements are completed, specific measurement points P, M and N are expanded to the whole circumferential surface and can be expressed as Pj，Mj，Nj(j denotes an index position, and j is 0,1,2,3 · n-1); the coordinates (X) of each specific measurement point in the fixed coordinate systemij，Yij，Zij) Can be inversely calculated by the following formula according to the relation between the lower shooting coordinate system and the fixed coordinate systemObtaining:
in the formula: when the i is respectively P, M or N, the measuring points with different indexing positions are represented; j denotes an index position number j of 0,1,2,3 · n-1;
(5) and (4) evaluating the shape error of the curved surface, and obtaining a 3 xn type value data dot matrix U after the measurement is completed according to the step (4), wherein the method is specifically as follows:
U＝[Pj,Mj,Nj]T (Ⅵ)
the lattice U can construct a lip surface by utilizing a B spline surface interpolation method, and the equation of the B spline surface is as follows:
in the formula: u is more than or equal to 0 and less than or equal to 1, v is more than or equal to 0 and less than or equal to 1, Bi,1(u) and Bj,3(v) Is a basis function, ri,jThe data dot matrix U of the model value is obtained;
two closed lip curved surfaces S on the oil seal main lip in the fixed coordinate system can be obtained after the curved surface equation (VII) is solved1，S2；
Creating a standard lip surface S under a fixed coordinate system01，S02(ii) a Because the lip curved surface is sine wave, the lip curved surface S is rotated through coordinate transformation1，S2Peak point of the waveform and standard lip curved surface S01，S02The model peak value reference is coincident, and the rotated lip curved surface is recorded as S11，S21；
For evaluating lip camber S11，S21Taking the lip curved surface S as the curved surface shape error11For example, at the lip curved surface S11Two parameter points are inserted between every two model value points obtained by measuring in the u and v directions, so that a 7 x 3n dot matrix on the lip curved surface is obtained; respectively calculating the distance D from each point to the standard lip curved surfaces1i(i is 1,2,3 … 7 × 3n) is a lip curved surface S11The curved surface deviation can be drawn by utilizing the deviation value of each point, the shape error of the curved surface can be visually shown, and in the specific numerical evaluation, the maximum value D in the curved surface deviation is takens1maxAnd average value Ds1eTwo indexes are used for evaluating the shape error of the lip curved surface.
The invention has the beneficial effects that:
1. the measuring device and the measuring method provided by the invention effectively solve the problem that the existing measuring device is difficult to accurately measure the shape error of the curved surface of the lip of the wave-shaped lip oil seal, can effectively detect the manufacturing precision of the wave-shaped lip oil seal, and ensure the working performance of the oil seal.
2. Compared with the traditional contact measurement methods such as a probe measuring head and the like, the measuring device adopts non-contact measurement, does not apply external force to the oil seal of the soft material to cause deformation of the oil seal, and effectively ensures the measurement precision.
3. The measuring device can measure the lip curved surface shape error of the waveform lip oil seal and can also be used for measuring the lip waveform curve error of the waveform lip oil seal. In addition, the method can be suitable for detecting the shape error of the complex cylindrical curved surface object or performing reverse engineering data measurement on the complex cylindrical part, and has wide application range and strong applicability.
Drawings
FIG. 1 is a schematic structural diagram of a measuring device according to the present invention;
FIG. 2 is a partial schematic view of a measuring head and oil seal;
FIG. 3 is a longitudinal cross-sectional view of the telescoping cross-piece;
FIG. 4 is a transverse cross-sectional view of the telescoping cross-bar;
FIG. 5 is a view of the telescoping cross-frame in the direction B;
FIG. 6 is a schematic view of an index position calibration point measurement;
FIG. 7 is a schematic view of a coordinate calculation of a single index position measurement point;
FIG. 8 is a schematic diagram comparing lip curvatures;
wherein: 1. a working platform; 2. an angle index indicator; 3. an angle index plate support table; 4. an angle index plate; 5. a working circular table; 6. a right-angle positioning block; 7. a column knob; 8. a threaded upright post; 9. a longitudinal laser range finder; 10. a lifting support; 11. a guide sleeve; 12. positioning a nut; 13. a guide post; 14. a telescopic cross frame knob; 15. a transverse laser range finder; 16. a telescopic cross frame; 16-1, a telescopic section of a telescopic cross frame; 16-2, a telescopic cross frame fixing section; 16-3, a telescopic cross frame stud; 16-4, a lower end cover; 16-5, an upper end cover; 16-6, fastening screws; 17. a target; 18. a measuring rod; 19. a measuring head; 20. an upper macro camera; 21. a point laser source; 22. a lower macro camera; 23. a wave-shaped lip oil seal; 24. and (4) a computer.
Detailed Description
The present invention will be further described by way of examples, but not limited thereto, with reference to the accompanying drawings.
Example 1:
as shown in fig. 1 to 5, the present embodiment provides a device for measuring a waveform lip oil seal lip curved surface shape error, which includes four parts of a positioning and measuring adjusting device, a camera adjusting device, a measuring device and a computer:
the positioning and measuring adjusting device comprises a working platform 1, the working platform 1 is rectangular, a circular angle index plate supporting platform 3 is placed on the working platform 1, and the circle center of the angle index plate supporting platform 3 and the center of the working platform 1 are on the same vertical line; an angle indexing disc 4 and a working circular table 5 are concentrically arranged on the angle indexing disc support table 3 in sequence; a right-angle positioning block 6 is mounted on the working circular table 5, the right-angle positioning block 6 is driven by a linear motor, a moving slide rail is arranged along the radius direction of the working circular table 5, the right-angle positioning block 6 is mounted on the moving slide rail and translates along the moving slide rail, and the moving distance of the right-angle positioning block 6 can be calculated by a related program in a computer 24; subsequently, after the position of the right-angle positioning block 6 is determined, the wave-shaped lip oil seal 23 is placed close to the right-angle positioning block 6, so that the wave-shaped lip oil seal 23 and the circle center of the working circular table 5 are on the same vertical line; the working platform 1 is also provided with an angle indexing indicator 2, and the angle indexing indicator 2 is matched with scales on the angle indexing disc 4 and used for reading the rotating angle of the angle indexing disc 4. Wherein the shapes of the angle indexing disc and the working circular table are also circular; the centers of the working circular table, the angle index plate supporting table and the working platform are on the same vertical line.
Among the camera adjusting device: a threaded upright post 8 is arranged at the middle point of the wide side of the working platform 1 close to the edge; the lower end of the threaded upright post 8 is provided with an upright post knob 7, the threaded upright post 8 can be rotated by screwing the upright post knob 7, and meanwhile, a lifting support 10 matched with the threaded upright post 8 is enabled to move up and down, and the lifting support 10 is arranged on the threaded upright post 8 and is in threaded connection with the threaded upright post 8; guide sleeves 11 are fixed on two sides of the lifting support 10, the guide sleeves 11 are matched with guide posts 13 fixed on the working platform 1, so that the lifting support 10 cannot rotate along with the threaded upright post 8 and only moves up and down, and the two guide posts 13 are symmetrically arranged on two sides of the threaded upright post 8; when the lifting bracket 10 is adjusted to the corresponding position, the positioning nut 12 on the guide sleeve 11 can be screwed for positioning. The top end of the lifting support 10 is fixedly connected with a telescopic cross frame 16, and the tail end of the telescopic cross frame 16 is connected with a telescopic cross frame knob 14 which can rotate to adjust the length of the telescopic cross frame 16.
In the measuring device: the longitudinal laser range finder 9 is fixed on the lifting support 10 and is positioned below the telescopic cross frame 16, and the measured value can be used for calculating the Z coordinate value of the macro camera. The transverse laser range finder 15 is positioned above the telescopic cross frame 16 and fixed on the lifting support 10, a target 17 is fixed at the front end of the telescopic cross frame 16 and matched with the transverse laser range finder 15, and the measured distance can be used for calculating the Y coordinate value of the microspur camera. The measuring rod 18 is arranged right below the target 17, the top end of the measuring rod 18 is fixedly connected with the telescopic cross frame 16, the measuring head 19 is fixed at the bottom end of the measuring rod 18, and on the measuring head 19, an upper microspur camera 20, a point laser source 21 and a lower microspur camera 22 are vertically arranged in a row.
The structure of the telescopic cross frame 16 is shown in fig. 3, 4 and 5, and comprises a telescopic section 16-1 and a fixed section 16-2, the telescopic cross frame comprises a stud 16-3, a lower end cover 16-4 and an upper end cover 16-5, wherein a telescopic section 16-1 is in threaded connection with the stud 16-3 and is sleeved in from the tail end of a fixed section 16-2, the lower end cover 16-4 and the upper end cover 16-5 are vertically matched and are arranged at the tail end of the fixed section 16-2 through a fastening screw 16-6 to prevent the stud 16-3 from falling off backwards, one end of the stud 16-3 penetrates through the lower end cover 16-4 and the upper end cover 16-5 and is connected with a telescopic cross frame knob 14, the telescopic section 16-1 is matched with the fixed section 16-2 in a protruding edge and groove mode, and the telescopic cross frame knob 14 is screwed to adjust the extension length of the telescopic section 16-1.
The angle indexing indicator 2, the longitudinal laser range finder 9, the transverse laser range finder 15, the upper macro camera 20, the lower macro camera 22 and the linear motor are respectively connected with a computer 24, and the computer 24 realizes information acquisition, automatic operation and control.
The measuring device is provided with a fixed coordinate system, the origin O of the fixed coordinate system is positioned at the center of a circle of the working circular table 5, the X axis is parallel to the wide side of the working platform 1, the Y axis is parallel to the long side of the working platform 1, and the Z axis is determined according to the right-hand criterion.
Example 2:
by using the measurement apparatus described in embodiment 1, this embodiment explains a method for measuring a shape error of a lip curved surface of a waveform lip oil seal, and the oil seal to be measured selected in this embodiment is a four-cycle sine waveform lip oil seal, and its specific measurement process is as follows:
(1) the position of the right-angle positioning block 6 is determined. The radius of the outer circular surface of the wave-shaped lip oil seal 23 to be measured is known as R1The radius of the circular hole at the center of the working circular table 5 is r0. The initial position of the right-angle point in the right-angle positioning block 6 is positioned at the edge of the central circular hole. The radius of the outer circular surface is R1The wave-shaped lip oil seal 23 and the working circular table 5 are concentrically arranged, the right-angle positioning block 6 needs to move by a distance L, and a specific numerical value is determined by the following formula and can be obtained by calculation of the computer 24.
After the position of the right-angle positioning block 6 is determined, the measuring head 19 is adjusted to the highest point to facilitate the placement of the wave-shaped lip oil seal 23, then the wave-shaped lip oil seal 23 is placed in close contact with the right-angle positioning block 6, and then the straight-line motor drives the right-angle positioning block 6 to move for a distance L, so that the wave-shaped lip oil seal 23 is ensured to be concentric with the working circular table 5.
(2) The position of the lower macro camera 22 is determined and the photographing measurement is performed. For convenience of calculation, the position of the lower macro camera 22 is taken as a reference. By observing the upper and lower macro cameras 20 and 22The upright knob 7 is rotated to adjust the lifting bracket 10. As shown in fig. 6, the point laser source 21 is made to irradiate on the first main lip curve LPForming a measuring point P; the telescopic cross frame knob 14 is then turned to adjust the length of the telescopic cross frame 16 to control the distance between the upper and lower macro cameras 20 and 22 and the inner ring surface of the oil seal so that the image formed on the computer 24 is the clearest. Recording the reading L of the transverse laser distance measuring device 15 at this time after the adjustment is completed1PAnd the reading L of the longitudinal laser distance measuring instrument 92P. The lower macro camera 22 takes a picture APThe upper macro camera 20 takes a picture BP. The position coordinate of the center of the lower macro camera 22 in the fixed coordinate system at this time is (X)sP，YsP，ZsP)。
Then the point laser sources 21 are respectively irradiated on the second lip curves L by adjusting the lifting support 10MAnd a third lip curve LNAbove, measurement points M and N are formed. The readings of the transverse laser range finders 15 at the two positions are respectively L1MAnd L1NThe readings of the longitudinal laser range finder 9 are L respectively2MAnd L2N. The lower macro cameras 22 take pictures A respectivelyMAnd AN(ii) a The upper macro camera 20 takes the pictures B respectivelyMAnd BN. The position coordinates corresponding to the lower macro camera 22 are (X) respectivelysM，YsM，ZsM) And (X)sN，YsN，ZsN)。
The coordinate values of the different measurement positions of the lower macro camera 22 are determined by the following formula:
in the formula: i represents different measuring points when P, M or N is taken respectively; c1The distance from the central line of the threaded upright post 8 to the center of the transverse laser range finder 15; c2The distance from the central line of the threaded upright post 8 to the origin O of the fixed coordinate system; c3The distance from the origin O of the fixed coordinate system to the plane of the working platform 1 is obtained; c4Is a lower microspur camera 22 center to longitudinal laser range finder9 distance of the center.
The distance between the upper macro camera 20 and the lower macro camera 22 in the Z-axis direction is T, and the position coordinate of the upper macro camera 20 is (X) on the premise that the position coordinate of the lower macro camera 22 is determinedsi,Ysi,Zsi+T)。
(3) And processing the single measurement position photo data. The picture a taken by the macro camera 22 is removed herei(i represents different measuring points when P, M or N are taken respectively) and a picture B taken by a macro camerai(i represents different measurement points when P, M or N is taken for each) are treated in the same way. Since the image points in the picture are in pixel units, it is necessary to establish a pixel image coordinate system { o, u, v } and a physical image coordinate system { o in millimeters1X, z }. As shown in fig. 7: the origin o of the image coordinate system in pixels is located in the lower left corner of the photograph, with the u-axis horizontally to the right and the v-axis vertically up. Origin o of physical image coordinate system1Located at a pixel coordinate of (u)0，v0) On the pixel point(s), the x-axis is horizontally towards the right, and the z-axis is vertically upwards. The translation between the two image coordinates is shown as follows:
in the formula: k is multiplied by l is the size of the pixel point, k and l are millimeters, and the k and l belong to the internal parameters of the macro camera.
Known photograph APThe pixel coordinate of the middle measurement point P is (u)p，vp) Conversion from the above equation to the physical image coordinate system { o }1And the coordinate value under x, z is (x)p，zp). The coordinates of the corresponding measuring points in the other pictures in the coordinate system of the physical image can also be obtained by the formula (II).
To further convert the coordinates of the points into the camera coordinate system, a lower camera coordinate system { O } is establishedx1,Xx1,Yx1,Zx1}: origin Ox1At the center of the lower macro camera 22, Xx1Axis and Zx1The axes being parallel to the x-and z-axes, respectively, Yx1And the axis is vertically intersected with the image plane, and the intersection point is the origin of the physical image coordinate system. Simultaneously establishing an upper camera coordinate system (O)x2,Xx2,Yx2,Zx2}: origin Ox2At the center of the upper macro camera 20, Xx2Axis and Zx2The axes being parallel to the x-and z-axes, respectively, Yx2The axis is perpendicularly intersected with the image plane, and the intersection point is the picture BiThe origin of the physical image coordinate system.
Coordinate Y of measuring point in lower camera coordinate systemx1iThe binocular vision distance measurement principle is obtained by the following formula:
in the formula: f is the focal length of the macro camera, belonging to the internal parameter of the camera, | zAiI and I zBiI is the measurement point in photograph AiAnd photograph Bi(i represents different measurement points when P, M or N is taken for each) the absolute value of the z coordinate in the physical image coordinate system.
Coordinate value X of any measuring point in lower camera coordinate system at single indexing positionx1iAnd Zx1iThe value can be obtained by back-calculation from:
in the formula: i denotes a different measuring point for each index position when P, M or N is taken, respectively.
After the calculation is completed, the coordinates of any measuring point in the lower camera coordinate system can be expressed as (X)x1i,Yx1i,Zx1i)。
(4) After the above operation is completed, the inner ring surface of the wave lip oil seal 23 is subjected to indexing measurement in the circumferential direction and the coordinates of all the measurement points are calculated. Indexing angle is as follows
(the value range is 5-10 degrees), then correspondingly haveAnd an indexing position (measuring position), wherein the default initial measuring position is a 0 th indexing position. The wave-shaped lip oil seal 23 is driven to rotate by the working circular table 5 to realize the photographing measurement of each indexing position, and the process can also be regarded as that the upper macro camera 20 and the lower macro camera 22 rotate relative to the wave-shaped lip oil seal 23 to carry out measurement. After all the measurement positions are completely measured, the specific measurement points P, M and N in the fourth step extending to the whole circumference surface can be expressed as Pj，Mj，Nj(j denotes an index position, and j is 0,1,2,3 · n-1). Coordinates (X) of each specific measuring point in a fixed coordinate systemij，Yij，Zij) The relationship between the camera coordinate system and the fixed coordinate system can be inversely calculated by the following equation:
in the formula: when the i is respectively P, M or N, the measuring points with different indexing positions are represented; j denotes an index position number j of 0,1,2,3 · n-1.
(5) And (5) evaluating the shape error of the curved surface. After the measurement is completed, a 3 xn type value data lattice U is obtained, which is specifically as follows:
U＝[Pj,Mj,Nj]T (Ⅵ)
constructing a lip curved surface by a lattice U by using a B spline surface interpolation method; the B-spline surface equation in this embodiment is as follows:
in the formula: u is more than or equal to 0 and less than or equal to 1, v is more than or equal to 0 and less than or equal to 1, Bi,1(u) and Bj,3(v) Is a basis function, ri,jAnd the data matrix is the model value data lattice U.
Two closed lip curved surfaces S on the oil seal main lip in the fixed coordinate system can be obtained after the curved surface equation (VII) is solved1，S2；
Under a fixed coordinate systemCreating a standard lip surface S01，S02(ii) a Because the lip curved surface is sine wave, the lip curved surface S is rotated through coordinate transformation1，S2Peak point of the waveform and standard lip curved surface S01，S02The model peak value reference is coincident, and the rotated lip curved surface is recorded as S11，S21；
For evaluating lip camber S11，S21Taking the lip curved surface S as the curved surface shape error11For example. At lip curved surface S11Two parameter points are inserted between every two model value points obtained by measuring in the u and v directions, so that a 7 x 3n dot matrix on the lip curved surface is obtained. Respectively calculating the distance D from each point to the standard lip curved surfaces1i(i is 1,2,3 … 7 × 3n) is a lip curved surface S11The curved surface deviation cloud picture can be drawn by utilizing the deviation value of each point, and the shape error of the curved surface is visually shown. In the specific numerical evaluation, the maximum value D of the deviation of the curved surface is takens1maxAnd average value Ds1eTwo indexes are used for evaluating the shape error of the lip curved surface.
Claims (5)
1. A measuring method of a waveform lip oil seal lip curved surface shape error measuring device comprises a positioning and measuring adjusting device, a camera adjusting device, a measuring device and a computer:
the positioning and measuring adjusting device comprises a working platform, an angle index plate supporting platform and an angle index indicator are arranged on the working platform, and an angle index plate and a working circular table are concentrically arranged on the angle index plate supporting platform;
the camera adjusting device comprises a threaded upright post, a lifting support and a telescopic cross frame, the threaded upright post is arranged at the middle point of the side edge of the working platform, guide posts are symmetrically arranged on two sides of the threaded upright post, the lifting support is in threaded connection with the threaded upright post, guide sleeves are arranged on two sides of the lifting support and are installed on the guide posts, and the tail end of the telescopic cross frame is connected to the top end of the lifting support;
the measuring device comprises a longitudinal laser range finder, a transverse laser range finder, a target, a measuring rod, a measuring head, an upper microspur camera, a point laser source and a lower microspur camera, wherein the transverse laser range finder and the longitudinal laser range finder are arranged on a lifting support and are respectively positioned on the upper side and the lower side of a telescopic cross frame;
the angle indexing indicator, the longitudinal laser range finder, the transverse laser range finder, the upper microspur camera and the lower microspur camera are respectively connected with the computer;
the method is characterized by comprising the following steps:
(1) firstly, setting a fixed coordinate system, setting an original point O of the fixed coordinate system at the circle center of a working circular platform, wherein an X axis is parallel to the wide side of a rectangular working platform, a Y axis is parallel to the long side of the rectangular working platform, and a Z axis is determined according to a right-hand rule;
then an oil seal is placed on the working circular table, and the center of the oil seal is coincided with the circle center of the working circular table by means of a right-angle positioning block;
(2) the position of the lower microspur camera is taken as a reference, the lifting support is adjusted by observing the amplified images shot by the upper microspur camera and the lower microspur camera, and finally point laser is irradiated on a first main lip curve L of the oil sealPForming a measuring point P; then adjusting the length of the telescopic cross frame to control the distance between the upper and lower macro cameras and the surface of the inner ring of the oil seal, so that an image formed on a computer is the clearest; recording the reading L of the transverse laser range finder at the moment after the adjustment is finished1PAnd reading L of longitudinal laser range finder2PThe lower microspur camera takes a photo APTaking a picture B by an upper macro cameraPAt this time, the position coordinate of the center of the lower macro camera in the fixed coordinate system is (X)sP，YsP，ZsP)；
Then point laser is respectively irradiated on a second lip curve L by adjusting the lifting supportMAnd a third lip curve LNRespectively forming a measuring pointM and N, the readings of the transverse laser range finder are respectively L at the positions of the two measuring points M and N1MAnd L1NThe readings of the longitudinal laser range finder are L respectively2MAnd L2NThe lower macro camera takes a photo A respectivelyMAnd ANThe upper macro camera takes a picture B respectivelyMAnd BNThe position coordinates corresponding to the lower macro cameras are respectively (X)sM，YsM，ZsM) And (X)sN，YsN，ZsN)；
By using the method, the position coordinate values corresponding to the macro cameras at different measuring points are determined by the following formula:
in the formula: i represents different measuring points when P, M or N is taken respectively; c1The distance from the center line of the threaded upright column to the center of the transverse laser range finder is obtained; c2The distance from the central line of the threaded upright post to the origin O of the fixed coordinate system; c3The distance from the origin O of the fixed coordinate system to the plane of the working platform; c4The distance from the center of the lower macro camera to the center of the longitudinal laser range finder;
the distance between the upper macro camera and the lower macro camera in the Z-axis direction is T, and the position coordinate of the upper macro camera is (X) on the premise that the position coordinate of the lower macro camera is determinedsi,Ysi,Zsi+T)；
(3) Single measurement position photo data processing, photo A taken by following macro cameraiExpounded, picture B taken by macro cameraiProcessing according to the same method, wherein when the I is respectively P, M or N, different measurement points are represented; because the image point in the photo is in pixel unit, the pixel image coordinate system { o, u, v } and the physical image coordinate system { o in millimeter unit are established1X, z }; wherein the origin o of the image coordinate system in pixel units is located at the lower left corner of the photograph, the u-axis is horizontally to the right, the v-axis is vertically upward, wherein the origin o of the physical image coordinate system1Is located on the imageThe element coordinate is (u)0，v0) The x axis is horizontally towards the right, the z axis is vertically towards the upper, and the conversion relation between the two image coordinates is shown as the following formula:
in the formula: k multiplied by l is the size of a pixel point, and k and l are millimeters and belong to internal parameters of a macro camera;
known photograph APThe pixel coordinate of the middle measurement point P is (u)p，vp) Converted to the physical image coordinate system { o } by equation (II)1And the coordinate value under x, z is (x)p，zp) The coordinates of the corresponding measuring points in the other photos in the physical image coordinate system can also be obtained by the formula (II);
to further convert the coordinates of the measurement points into the camera coordinate system, a lower camera coordinate system { O } is establishedx1,Xx1,Yx1,Zx1}: origin Ox1At the center of the lower macro camera, Xx1Axis and Zx1The axes being parallel to the x-and z-axes, respectively, Yx1The axis is vertically intersected with the image plane, and the intersection point is the origin of the physical image coordinate system; simultaneously establishing an upper camera coordinate system (O)x2,Xx2,Yx2,Zx2}: origin Ox2At the center of the upper macro camera, Xx2Axis and Zx2The axes being parallel to the x-and z-axes, respectively, Yx2The axis is perpendicularly intersected with the image plane, and the intersection point is the picture BiThe origin of the physical image coordinate system;
coordinate Y of measuring point in lower camera coordinate systemx1iThe binocular vision distance measurement principle is obtained by the following formula:
in the formula: f is the focal length of the macro camera and belongs to the internal parameters of the camera; | zAiI and I zBiI is the measurement point in photograph AiAnd photograph BiWhen the absolute value of the z coordinate in the physical image coordinate system, i is P, M or N respectively, different measuring points are represented;
coordinate value X of any measuring point in lower camera coordinate system at single indexing positionx1iAnd Zx1iThe value can be obtained by back-calculation from:
in the formula: when the i is respectively P, M or N, the measuring points with different indexing positions are represented;
after the calculation is completed, the coordinates of any measuring point in the lower camera coordinate system can be expressed as (X)x1i,Yx1i,Zx1i)；
(4) After the operation is finished, the surface of the inner ring of the oil seal is subjected to indexing measurement along the circumferential direction, and the coordinates of all measurement points are calculated, wherein the indexing angle is
The value range is 5-10 degrees, then correspondingly haveObtaining n measuring positions by indexing positions, wherein the default initial measuring position is the 0 th indexing position; the oil seal is driven to rotate by the working circular table to realize the photographing measurement of each indexing position, and after all the measurements are completed, specific measurement points P, M and N are expanded to the whole circumferential surface and can be expressed as Pj，Mj，NjJ denotes an index position number j of 0,1,2,3 · n-1; the coordinates (X) of each specific measurement point in the fixed coordinate systemij，Yij，Zij) The relationship between the camera coordinate system and the fixed coordinate system can be inversely calculated by the following equation:
in the formula: when the i is respectively P, M or N, the measuring points with different indexing positions are represented; j denotes an index position number j of 0,1,2,3 · n-1;
(5) and (4) evaluating the shape error of the curved surface, and obtaining a 3 xn type value data dot matrix U after the measurement is completed according to the step (4), wherein the method is specifically as follows:
U＝[Pj,Mj,Nj]T (Ⅵ)
the lattice U can construct a lip surface by utilizing a B spline surface interpolation method, and the equation of the B spline surface is as follows:
in the formula: u is more than or equal to 0 and less than or equal to 1, v is more than or equal to 0 and less than or equal to 1, Bi,1(u) and Bj,3(v) Is a basis function, ri,jThe data dot matrix U of the model value is obtained;
two closed lip curved surfaces S on the oil seal main lip in the fixed coordinate system can be obtained after the curved surface equation (VII) is solved1，S2；
Creating a standard lip surface S under a fixed coordinate system01，S02(ii) a Because the lip curved surface is sine wave, the lip curved surface S is rotated through coordinate transformation1，S2Peak point of the waveform and standard lip curved surface S01，S02The model peak value reference is coincident, and the rotated lip curved surface is recorded as S11，S21；
For evaluating lip camber S11，S21Taking the lip curved surface S as the curved surface shape error11For example, at the lip curved surface S11Two parameter points are inserted between every two model value points obtained by measuring in the u and v directions, so that a 7 x 3n dot matrix on the lip curved surface is obtained; respectively calculating the distance D from each point to the standard lip curved surfaces1iIs a lip curved surface S11The curved surface deviation i is 1,2,3 … 7 multiplied by 3n, a curved surface deviation cloud picture can be drawn by utilizing the deviation value of each point, the shape error of the curved surface is visually shown, and the curved surface deviation is evaluated in a specific numerical valueTaking the maximum D of the deviations of the curved surfaces1maxAnd average value Ds1eTwo indexes are used for evaluating the shape error of the lip curved surface.
2. The method for measuring the shape error of the curved surface of the lip of the wave lip oil seal according to claim 1, wherein a moving slide rail is arranged on the working circular table in the radial direction, a right-angle positioning block is arranged on the moving slide rail, the right-angle positioning block is driven by a linear motor to translate along the moving slide rail, and the linear motor is further connected with a computer.
3. The method for measuring the waveform lip oil seal lip shape error measurement device according to claim 1, wherein a column knob is arranged at the bottom end of the threaded column, and a positioning nut is arranged on the guide sleeve.
4. The method for measuring the waveform lip oil seal lip mouth curved surface shape error of claim 1, wherein the tail end of the telescopic cross frame is provided with a telescopic cross frame knob.
5. The method for measuring the waveform lip oil seal lip mouth curved surface shape error measuring device according to claim 1, wherein the shape of the working platform is rectangular, and the shapes of the angle index plate support platform, the angle index plate and the working circular platform are circular; the centers of the working circular table, the angle index plate supporting table and the working platform are on the same vertical line.
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