CN102538700B - Helical Rotor Profile Error Measuring Instrument - Google Patents

Abstract

The invention discloses a profile error measuring instrument for a helical rotor, which is characterized in that the measured rotor is supported between a headstock thimble and a tailstock thimble, and a rotary table drives the measured helical rotor to rotate; a mobile worktable is provided, A measuring unit is arranged on the mobile workbench, and a long grating sensor for detecting the position of the moveable workbench is arranged in the measure unit, and a laser displacement sensor is fixedly arranged on the electric turntable. The invention utilizes a laser displacement sensor to obtain the original measurement data of the surface characteristics of the helical rotor under the cooperation of two rotary tables and a one-dimensional translation table, and then obtains the helical rotor profile after corresponding data processing and coordinate transformation. Surface profile error data and error evaluation results are given. It has a simple structure and good processing and assembly capabilities. It can measure the surface profile error of various helical surfaces and is compatible with other types of sensors for precise measurement of other parameters.

Description

Helical Rotor Profile Error Measuring Instrument

technical field

The invention relates to a measuring device, more specifically, it is used to measure the relevant parameters of various curved surfaces with helical characteristics, and can be applied to helical gears, precision screw rods, compressor helical rotors, helical pump rotors, gear processing tools Devices for precision measurement of parts and components.

Background technique

In the modern machinery industry, many kinds of surface error measurement problems with spiral characteristics are involved. For example, the screw rotor, the core component of the screw compressor, its shape and precision directly affect the working efficiency, noise and vibration level and service life of the compressor; for example, the hob for processing gears, its contour surface error will be directly and periodically reproduced on the machined gears. Therefore, the surface error measurement technology and evaluation technology with spiral characteristics are increasingly concerned and valued by domestic academic circles and business circles. At present, the detection method of most domestic enterprises is to use a general-purpose three-coordinate measuring machine to reflect the quality of the entire screw rotor by detecting the cross-section lines at different axial cross-section positions of the rotor. This measurement method has the following problems:

1. The price of the three-coordinate measuring machine is high, and the rotor measurement requires corresponding special detection software. The price of the software is also high, and the operation is relatively complicated, and the technical requirements for the operator are also relatively high. All of these have restricted the popularization and promotion of the method itself.

2. Three-coordinate measuring machines generally use high-precision trigger ball probes. Due to the complex structure of the end surface profile and large curvature changes, the error compensation of the probe ball radius becomes complicated. So far, there are still theoretical difficulties and deficiencies in the academic field. ;

3. The measurement time is long, which is only suitable for random inspection, not suitable for rapid detection and online detection, and it is difficult to meet the needs of rotor manufacturing enterprises.

4. It can only measure the linear error of the two-dimensional section profile in the rotor shaft section, but cannot measure the profile of the entire spiral profile from the perspective of three-dimensional space, let alone evaluate the profile error of the measured rotor surface.

Contents of the invention

In order to avoid the shortcomings of the above-mentioned prior art, the present invention provides a screw rotor profile error measuring instrument to realize the efficient, automatic and accurate detection of the screw rotor profile error parameters, and promote the related three-dimensional profile error measurement instrument. The further development of the theory of profile error evaluation.

The present invention solves technical problem and adopts following technical scheme:

The structural features of the screw rotor profile error measuring instrument of the present invention are:

On the base, a headstock and a tailstock are respectively arranged at the two ends of the "T"-shaped long slot arranged along the X direction, and on the opposite end faces between the headstock and the tailstock, on the same axis, there are respectively arranged A headstock thimble and a tailstock thimble, the rotor to be tested is supported between the headstock thimble and the tailstock thimble;

An electric rotary table is fixedly arranged on the head frame, and the center of rotation of the rotary table located in the electric rotary table and driven by the electric rotary table coincides with the axis of the thimble of the head frame. The front end surface of the fork is connected to a shift fork through a shift lever, and a pair of fork heads of the shift fork are respectively provided with clamping screws for driving the measured helical rotor, and the clamping screws are radially clamped on the Measure the first shaft end of the helical rotor;

An electric translation platform is set on the base, and a mobile workbench driven by a stepping motor through a ball screw pair and can slide on a linear track is set on the electric translation platform. The linear track and the "T" shape The long slots are arranged in parallel; a column is fixedly arranged in the Z direction on the mobile workbench, and a beam is installed on the top of the column as a cantilever, and the front end of the beam is above the rotor to be tested; the front end of the beam is set An electric turntable, the rotating shaft of the electric turntable is arranged in the X direction;

The measuring unit is set up, including configuring a circular grating sensor in the electric rotary table for measuring the rotation angle of the rotary table; a long grating sensor for detecting the position of the mobile worktable is set on the electric translation table; A laser displacement sensor is fixedly arranged on the electric turntable; the optical axis of the laser displacement sensor passes through the rotation axis of the electric turntable.

The structural features of the screw rotor profile error measuring instrument of the present invention also lie in:

A tailstock positioning mechanism is provided, which is to set a pull rod bushing on one side of the tailstock. The pull rod runs through the pull rod bushing and can slide axially in the pull rod bushing. A pressure block is fixedly connected to the front end of the pull rod. The rear end of the pull rod is fixedly connected with a handle, and a compression spring is installed between the sleeve of the pull rod and the handle, and the pressing block is pressed against the positioning groove in the base by the pressure of the compression spring; an anti-rotation pin is set, and the anti-rotation pin One end of the revolving pin is threadedly connected with the briquetting block, and the other end is inserted in the pin hole on the bottom surface of the tailstock.

Each positioning surface is set on the base, including: the first elevation A and the second elevation D parallel to each other; the first plane E, the second plane F and the third plane G of the same height, and each elevation and The planes are perpendicular to each other; the electric translation platform is fixed on the third plane G by bolts, and the side of the electric translation platform is in contact with the second facade D and positioned; the headstock and the tailstock are respectively fixed on the first plane E and the second plane. On the second plane F, the sides of the headstock and the tailstock are against the first facade A.

The invention utilizes the laser displacement sensor to obtain the original measurement data about the surface characteristics of the helical rotor under the cooperation of the motion of the two rotary tables and the one-dimensional translation table, and then obtains the surface profile of the helical rotor through corresponding data processing and coordinate transformation Degree error data and error evaluation results are given. Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. The present invention upgrades the rotor measurement from two-dimensional line profile measurement and evaluation to the surface profile error measurement and evaluation of the full helical surface of the rotor in three-dimensional space, and the acquired measurement data can realize the three-dimensional reconstruction of the rotor profile.

2. The invention adopts machine vision non-contact measurement to realize automatic high-precision measurement of the key profile parameters of the helical rotor, avoids the problem of probe radius compensation in the measurement of the three-coordinate measuring machine, and is conducive to improving the measurement accuracy.

3. The present invention uses a shift fork to drive the measured rotor, and uses two dead centers to position the measured rotor. Compared with the direct drive of the main shaft, the influence of the main shaft motion error on the measurement accuracy is well eliminated.

4. The present invention can not only measure the two-dimensional linear profile of the rotor in any shaft section, but also measure and evaluate the surface profile error of the rotor helical surface in the three-dimensional space, and realize the three-dimensional reconstruction of the helical characteristic surface.

5. The present invention can be used to measure the error of any helix on the helical surface when the laser displacement sensor is removed, the inductance sensor or other types of sensors are replaced. The methods are consistent and have direct significance and value for analyzing the processing technology.

6. The present invention can be widely used in the measurement of precision mechanical parts such as helical gears, precision helical screw rods, and gear processing tools;

Including the measurement of parameters such as helicoid lead, lift angle, and pitch circle diameter.

7. The present invention has good detection repeatability, high precision and high detection efficiency.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention;

Fig. 2 is the top view of Fig. 1;

Fig. 3 is the left view of Fig. 1;

Fig. 4 is the right view of Fig. 1;

Fig. 5 is a structural schematic diagram of the head frame in the present invention;

Fig. 6 is the left view of Fig. 5;

Fig. 7 is a structural diagram of a tailstock in the present invention;

Fig. 8 is the left view of Fig. 7;

Fig. 9 is a schematic diagram of the positioning surface of the base in the present invention;

Fig. 10 is a schematic diagram of laser displacement sensor measurement in the present invention;

Fig. 11 is a schematic diagram of a cylindrical coordinate measuring system in the present invention.

Labels in the figure: 1 head frame; 2 measured rotor; 3 tail frame; 4 base; 5 leveling feet; 6 electric translation platform; 7 screws; 8 T-bolts; ;12 column, 13 mobile table; 14 shift fork; 15 lever; 16 head frame thimble; 17 electric rotary table; Repin, 23 handles, 24 pull rods, 25 clip springs, 26 pull rod bushings, 27 pressure blocks, 28 standard arc surfaces; 29 standard parts brackets.

Detailed ways

Referring to Fig. 1, Fig. 2 and Fig. 3, the conical hole at the front end of the head frame 1 and the thimble pin 16 of the head frame are precisely matched with the conical surface. The head frame 1 is fixed on the base 4 with T-shaped screws 8, and the bottom of the base 4 is provided with leveling feet 5. It is used to adjust the levelness of the base 4; the driving rod 15 is fixedly connected to the rotary table 19 through the external thread at the front end, the cylindrical hole on the upper surface of the shifting fork 14 is in clearance with the driving rod 15, and a pair of the lower end is arranged to match the rotor to be tested. A threaded hole with the same axis position, the clamping screw 18 is screwed and passed through the threaded hole to clamp the measured helical rotor, so that the electric rotating table 17 drives the measured rotor 2 to rotate to achieve precise indexing.

Referring to Figures 5 and 6, the electric rotary table 17 fixed on the front end of the head frame by the electric rotary table base 20 is a commercially available standard component, driven by a stepping motor, and driven by a worm gear to drive its rotary table 19 Rotation, motorized rotary table 17 is equipped with a precision circular grating sensor to achieve angle measurement and precise graduation. In specific implementation, the electric rotating table 17 is fixed on the front end surface of the head frame 1 with screws, and its rotation axis coincides with the axis of the head frame thimble 16 .

Referring to Fig. 4, Fig. 7 and Fig. 8, the tapered surface of the tailstock thimble 21 is precisely matched with the tapered hole at the front end of the tailstock 3; a tailstock positioning mechanism is provided, which is to set the rod bushing 26 on one side of the tailstock 3 with screws, The pull rod 24 runs through the pull rod sleeve 26, and the cylindrical surface of the pull rod 24 fits with the cylindrical hole of the pull rod sleeve 26. The pull rod 24 can slide axially in the pull rod sleeve 26, and the front end of the pull rod 24 is fixedly connected with a pressure block 27. 24 rear ends are fixedly connected with handle 23 by screw thread, stage clip 25 is housed between pull rod bushing 26 and handle 23, press block 27 in the positioning groove in base 4 with the pressure of stage clip 25; Anti-rotation pin 22, one end of anti-rotation pin 22 is threadedly connected with briquetting block 27, and the other end is inserted in the pin hole of tailstock 3 bottom surface, and briquetting block 27 expands and contracts under the rotation of handle 23, thereby clamps or releases tailstock, prevents simultaneously The briquetting block 27 rotates.

Referring to Fig. 2, an electric translation platform 6 is set on the base 4, and a mobile workbench 13 driven by a stepping motor through a ball screw pair to slide on a linear track is set on the electric translation platform 6, and the linear track is in line with "T" "Type long grooves are arranged in parallel; on the mobile workbench 13, a column 12 is fixed in the Z direction, and a beam 11 is installed on the top of the column 12 as a cantilever, and the front end of the beam 11 is above the rotor to be tested; the front end of the beam 11 is set An electric turntable 9, the rotating shaft of the electric turntable 9 is arranged in the X direction;

As shown in Figure 2, in this embodiment, the rolling guide rail pairs are symmetrically arranged on both sides of the ball screw, parallel to the axis of the ball screw, the precision length measuring grating scale is arranged between the two guide rails, and the grating reading head is fixed on the moving The bottom of the workbench 13 is adjacent to the guide rail slider and the rolling nut; the mobile workbench 13 is connected with the slide block on the rolling guide rail and connected with the rolling nut by screws, and the column 12 is vertically fastened on the mobile workbench 13 by screws.

As shown in Figure 4, the bottom flange of the column 12 has four waist-shaped holes along the transverse direction, which are threadedly connected with the mobile workbench 13 on the electric translation platform 6, and the afterbody of the crossbeam 11 has an opening, which is clamped with the screw 7 On the column 12, so that the height of the crossbeam 11 can be adjusted according to the measurement needs; on the electric turntable 9, a laser displacement sensor 10 is fixed through an intermediate adapter plate; the optical axis of the laser displacement sensor 10 passes through the rotation axis of the electric turntable 9; The measuring principle of the displacement sensor 10 is the triangulation method. A beam of laser light is sent to a point on the surface to be measured, and the light is received by the CCD after the light turns back to know the displacement from the point to the sensor.

Referring to Fig. 9, in this embodiment, various positioning surfaces are set on the base 4, including: a first elevation A and a second elevation D parallel to each other; a first plane E, a second plane F and a third plane of equal height Plane G, and each facade and each plane are perpendicular to each other; the electric translation platform 6 is fixed on the third plane G by bolts, and the side of the electric translation platform 6 is offset and positioned against the second facade D; the head frame 1 and the tail frame 3 are respectively fixed on the first plane E and the second plane F, the side of the headstock 1 is used as the reference plane B and is against the first elevation A on the base 4, when the tailstock 3 is in the locked state, it acts as The side of the reference plane C is offset against the first elevation surface A of the base 4; the headstock 1 and the tailstock 3 have a common positioning surface, so as to ensure that the axes of the headstock thimble 16 and the tailstock thimble 21 coincide; in this embodiment, The third plane G of the electric translation stage 6 is coplanar with the positioning surfaces of the headstock 1 and the tailstock 3, that is, the first plane E and the second plane F, so that the direction of motion of the measuring unit driven by the electric translation stage can be guaranteed It is parallel to the axis determined by the top of the headstock and the top of the tailstock to form the reference movement required for measurement.

The hardware part of the computer processing unit has a data acquisition card, a motion control card and a conditioning circuit; the software components include measurement software and interface operation software, and the measurement software realizes data acquisition, coordinate change processing and measurement result evaluation; the operation interface mainly includes three stepping motors Motion control settings, measurement process operation control and other parts.

Measurement methods:

Before testing, the instrument needs to be calibrated with the standard arc surface 28 of the standard part; the standard part can be directly placed on one side of the base 4 with the standard part bracket 29 for ease of use; it can also be placed separately.

When testing, install the rotor under test between the thimble of the headstock and the thimble of the tailstock, and lock the tailstock. Move the mobile table 13 to one end of the rotor under test, turn the electric rotary table 17, and align the laser beam of the laser displacement sensor with the starting point of the axial section of the rotor under test. After the measurement starts, the electric rotary table 17 drives the rotor under test to rotate, and at the same time The electric translation table 6 drives the mobile worktable 13 to move from one end of the rotor under test to the other section, the rotation of the electric rotary table 14 and the movement of the electric translation table 6 are controlled by the computer and the speed ratio of the two is guaranteed; the measured rotor rotates once, The mobile table moves one lead of the helical rotor. According to the actual measurement needs of the helical rotor, the number of measurement sections within one lead can be set. For example, a male rotor of a certain type has five teeth, the lead angle is 240 degrees, and the lead is 278 mm. If m sections are selected in each tooth for measurement, the measurement starts in the first section at one end of the rotor under test. , the electric rotary table 17 rotates step by step during measurement, for example, every 0.1°, the linear displacement sensor obtains the distance r _i from it to a point on the measured surface, so that the rotation angle θ _i of the electric rotary table 17 corresponds to r _i one by one A set of polar coordinates is formed, which can accurately describe the shape line characteristics of the helical rotor in a section. After the first section is tested, the electric rotary table and the electric displacement table move synchronously, so that the second section to be tested enters the measurement position, realizing The second molded line profile is measured, and this cycle is performed until all m sections are measured. After the first tooth is measured, the electric turntable rotates n° (n=360/number of teeth) to measure the second tooth until all five teeth are measured.

同时一维电动位移台内的长光栅会记录测头的位移值，这样就构成了一个柱坐标测量系统，如图10和图11所示。在评定一个齿内的螺旋面的面轮廓度误差时，需要将前面所测得的每个截面内的极坐标参数(r_i，θ_i)经过坐标转换，统一到柱坐标内再进行单齿螺旋面的面轮廓度误差评定，同时也可以分析和判断出各齿面之间相互的位置误差。这种面轮廓度的评定和齿面相互位置误差的分析和测量是采用三坐标测量机无法办到的。也正是因为需要在两个坐标系之间进行转换和统一，为了保证测量精度的需要，仪器才需要用标准件进行上述的标定和校准。也可以利用一个齿内m个截面的轮廓参数重构出该齿的三维轮廓，从面轮廓度层面上对误差进行评定。甚至可以实现五个齿轮廓相对位置误差的评定和计算。After the measurement is completed, the designed measurement and error evaluation software first evaluates the profile error of m sections in a tooth and gives the result. The result given here is the line profile reflecting the rotor profile in a single shaft section. In fact, the rotation axis O ₁ O ₂ formed by the top of the headstock and the tailstock can be regarded as the X axis, and the circular grating sensor inside the concentrically arranged electric rotary table (17) on the headstock can record and measure the rotation angle of the rotor in real time

At the same time, the long grating in the one-dimensional electric translation stage will record the displacement value of the probe, thus forming a cylindrical coordinate measurement system, as shown in Figure 10 and Figure 11. When evaluating the surface profile error of the helical surface in a tooth, it is necessary to convert the polar coordinate parameters (r _i , θ _i ) in each section measured before into the cylindrical coordinates and then carry out the single tooth The surface profile error evaluation of the helical surface can also analyze and judge the mutual position error between the tooth surfaces. The evaluation of the surface profile and the analysis and measurement of the mutual position error of the tooth surface cannot be done by using a three-coordinate measuring machine. It is precisely because of the need to convert and unify between the two coordinate systems, in order to ensure the measurement accuracy, the instrument needs to use the standard parts for the above calibration and calibration. The three-dimensional profile of the tooth can also be reconstructed by using the profile parameters of m sections in a tooth, and the error can be evaluated from the surface profile level. It is even possible to evaluate and calculate the relative position error of the five tooth profiles.

Claims (3)

1. A screw rotor profile error measuring instrument, characterized in that: On the base (4), a headstock (1) and a tailstock (3) are respectively arranged at the two ends of the "T"-shaped long groove arranged along the X direction, and on the opposite end faces between the headstock and the tailstock 1. A headstock thimble (16) and a tailstock thimble (21) are respectively arranged on the same axis, and the measured rotor (2) is supported between the headstock thimble and the tailstock thimble; An electric rotary table (17) is fixedly arranged on the head frame (1), and the rotation of the rotary table (19) located in the electric rotary table (17) and driven by the electric rotary table (17) The center coincides with the axis of the headstock thimble (16), and a shift fork (14) is connected through a shift lever (15) on the front end face of the rotary table (19), on the shift fork (14) Clamping screws (18) for driving the measured helical rotor are respectively arranged on a pair of forks, and the clamping screws (18) are radially clamped on the first axial end of the measured helical rotor; An electric translation platform (6) is arranged on the base (4), and a mobile workbench ( 13), the linear track is arranged parallel to the "T"-shaped long slot; a column (12) is fixedly arranged in the Z direction on the mobile workbench (13), and a beam is arranged on the top of the column (12) in a cantilevered manner (11), the front end of the crossbeam (11) is above the measured rotor; an electric turntable (9) is arranged at the front end of the crossbeam (11), and the rotating shaft of the electric turntable (9) is arranged in the X direction ; Setting up a measuring unit includes configuring a circular grating sensor in the electric rotary table (17) for measuring the rotation angle of the rotary table (19); A long grating sensor that detects the position of the mobile worktable (13); a laser displacement sensor (10) is fixedly installed on the electric turntable (9); the optical axis of the laser displacement sensor (10) passes through the electric turntable (9) axis of rotation. 2. The screw rotor profile error measuring instrument according to claim 1, characterized in that a tailstock positioning mechanism is provided, which is to set a pull rod bushing (26) on one side of the tail stock (3), and a pull rod (24) It runs through the pull rod bushing (26) and can slide axially in the pull rod bushing (26). A pressure block (27) is fixedly connected to the front end of the pull rod (24), and the rear end of the pull rod (24) is fixedly connected to There is a handle (23), and a compression spring (25) is installed between the pull rod bushing (26) and the handle (23), and the press block (27) is pressed against the base (4) by the pressure of the compression spring (25). ) in the positioning groove; set an anti-rotation pin (22), one end of the anti-rotation pin (22) is threaded with the pressure block (27), and the other end is inserted into the pin hole on the bottom surface of the tailstock (3). 3. The screw rotor profile error measuring instrument according to claim 1, characterized in that each positioning surface is set on the base (5), including: a first elevation A and a second elevation D parallel to each other ; The first plane E, the second plane F and the third plane G of the same height, and each facade and each plane are perpendicular to each other; the electric translation platform (6) is fixed on the third plane G by bolts, and the electric translation The side of the platform (6) is against the second facade D and positioned; the headstock (1) and the tailstock (3) are respectively fixed on the first plane E and the second plane F, and the headstock (1) and the tailstock ( 3) The side faces against the first facade A.

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