In this paper, LabVIEW is used as a software development tool and design platform for the development of virtual instruments for cycloidal gear error measuring instruments. A virtual measuring instrument for measuring cycloidal gears has been developed. The computer software is used to realize some hardware functions of the analog instrument, and combined with the general data acquisition device to realize the real instrument function, it can continuously and automatically measure the tooth profile of the full gear, and realize the evaluation and display of multiple errors.
1 The error evaluation index determines the evaluation index of the cycloidal gear error. It must consider the use requirements, determine the items and tolerances of the user acceptance, and consider the possibility of manufacturing. Provide the manufacturer with inspection items and tolerances for process error analysis. , organically combine manufacturing and use. Since the process factors caused by the cycloidal gear error and the involute cylindrical gear error and its influence on the transmission have many similarities, most of the error items for evaluating the involute cylindrical gear can be used to evaluate the cycloidal gear error.
The main difference between the cycloidal gear and the involute gear is that the parameters of the tooth profile are different, and the influence of process factors such as trimming, machine tools and tools makes the tooth profile error a basic error of the cycloidal gear. In addition, the tooth tip and root of the cycloid gear participate in the meshing process, and the design tooth height is twice the eccentricity of the two sections of the transmission pair. Therefore, the tooth height deviation represents one of the important design parameters of the cycloidal gear. Error. At the same time, considering the tangential and radial error integrated surface generated by the cycloidal gear machining process and the repaired surface together form a complete parting surface, and TotalFaces=CavityFaces CoreFaces, (3) after checking, click OK. Go to the CreateCavityCore process.
(4) First create the cavity part, check whether the trimming direction of the parting surface is correct. If it is not correct, it can be reverse trimmed to complete the cavity and core.
3 Conclusion In the three-dimensional design and numerical control machining of injection molds, parting is a complicated and critical problem. In addition to being familiar with the corresponding functions of UGMdWizard modules, it also has design experience and compliance with design specifications. This paper takes the UMMoldWizard module as the platform, and takes the mobile Phone Case as an example, expounds and summarizes the injection molding process and principle of the injection mold, and provides the technical basis for the three-dimensional design of the injection mold and the subsequent CNC machining.
The possibility of influence and detection is therefore selected as the comprehensive index error, pitch cumulative error, pitch deviation and tooth height deviation as the evaluation index of cycloidal gear error detection. Here, a definition of each error and deviation is made. 1) Cross-section comprehensive error: On the axial section of the cycloidal wheel, the normal distance between the two nearest design tooth profiles of the actual tooth profile is included in the full tooth profile range.
2) Accumulated error of pitch: the absolute value of the difference between the actual arc length and the nominal arc length between any two identical flanks on the upper average circle of the cycloidal gear. 3) Pitch deviation: The difference between the actual pitch and the nominal pitch on the upper average circle of the cycloidal gear. 4) Tooth shape error: the normal distance between the two nearest design tooth shapes of the actual tooth profile in the range of the pitch angle of the cycloidal wheel. 5) Tooth height deviation: the difference between the actual tooth height of the cycloidal wheel and the nominal tooth height.
2 Mathematical model establishes the cycloidal profile curve, rc is the pitch radius of the cycloidal wheel, rb is the pitch radius of the pin gear, Rz is the radius of the center circle of the pin tooth, and rz is the radius of the pin gear. The equation of any point M on the theoretical tooth profile curve of the cycloidal wheel is: xo=Rz[sin-(K1/zb)sin(zb)]yo=Rz(cos-(K1/zb)cos(zb)] where K1 It is the short-width coefficient; zb is the number of needle teeth; it is the angle that the discussion point on the theoretical tooth profile of the cycloidal wheel is rotated relative to the center of the needle gear pitch circle.
Let the number of teeth of the cycloidal wheel be zc, and the angle between the common normal line MP and the X axis of the discussion point on the theoretical tooth profile of the cycloidal wheel is v, then the coordinate of the corresponding point K on the standard tooth profile is: x=xo rzcosvy=yo- Rzsinv (1) is the standard tooth profile rectangular coordinate equation of the cycloidal wheel. Where: cosv=[K1sin(zb)-sin]/1 K21-2K1cos(zc)sinv=[-K1cos(zb) cos]/1 K21-2K1cos(zc) is a comparison between convenient measured data and theoretical design values And the data processing of the detection error of the cycloidal wheel, the rectangular coordinate of the formula (1) is converted into polar coordinates, and the following conversion relationship is followed: =x2 y2=arccos(x/)3 Construction of the virtual instrument The detection system adopts a microcomputer as The core virtual measurement system uses a motor to drive the measured gear for rotational motion. The DC differential and angular encoders are picked up by the DC differential transformer displacement sensor and an incremental photoelectric shaft encoder. The angular encoder and the measured pendulum are respectively measured. The line gear is coaxially mounted, the spherical probe and the high-precision displacement sensor are mounted on the bracket that can be adjusted up and down, and the spherical contact is kept in contact with the tooth profile under the action of the radial measurement force, and the two signals are sent by the A/D digital-analog conversion card. In the microcomputer, the software program calculates and calculates various errors.
The mechanical system mainly includes a base (with guide rail), a cycloidal wheel positioning and clamping device, a cycloidal rotary drive device, a horizontal and vertical carriage adjustment device, a sensor positioning clamp device and the like.
4Program design and data processing LabVIEW is a graphical programming platform with high modularity and hierarchical features. It is relatively easy to implement the algorithm with hierarchical module, and the structure is clear. Therefore, the data acquisition program, the cycloid gear theoretical curve program and the tooth are used. Data processing programs for errors such as shape error, tooth height deviation, and pitch deviation are respectively made into subroutines (SubVI). The function of the main program is to coordinate the management of other subroutines and organically combine the subroutines. Block diagram of the program structure.
The signal picked up by the detection system enters the computer system through the sensor, signal demodulator, and A/D card. In addition to the useful information of the measured gear itself, it also contains various noise interferences and effects due to measurement force and mechanical transmission. The generated information, in order to eliminate the interference of various noises, weaken the excess components in the information, and improve the signal-to-noise ratio, it is necessary to pre-process the collected signals. The preprocessing is divided into two stages: phase sampling such as data and data smoothing. The data acquisition subroutine is called by the main program. LabVIEW can easily define the data sampling frequency of the A/D card for isochronous sampling. The pulse signal of the angular encoder is used to reduce the cutting force and the surface of the hole. Roughness.
3) Post design. The connecting rod is made of seamless steel pipe with a wall thickness of 3mm and a diameter of 18mm. The length depends on the depth of the hole. The drill bit and the post are connected by a rectangular thread. The rectangular threaded joint has high strength, is simple to manufacture, and is convenient for sharpening the drill bit. It is not advisable to use welded joints (not easy to sharpen after welding and to ensure the accuracy of the drill pipe).
3 The machining process firstly roughs the outer circle of the part and then installs it on the spindle of the lathe (three-jaw clamping at one end and one end with the center frame). When drilling the deep hole, the center drill and the twist drill are used to pre-drill the workpiece. Holes are then equipped using the above process. The length of the drill bit is gradually lengthened, and the drilling depth is slightly larger than one-half of the length of the workpiece. The U-turn uses the same clamping and machining method to drill the hole. Pay attention to the following issues when using:
1) The cutting speed should be between 3263r/min. The feed rate should be determined according to the cutting condition (determined by the sound generated by cutting), chip shape, machine load and other factors. The distance determined by each feed depth is filled with chips. Full drill chip pockets prevail.
2) It is advisable to trim the length of the cutting part of the drill bit to 6080mm, which is too long to cause drilling deviation and vibration.
3) Install the drill bit to be coaxial with the center of the workpiece, otherwise the hole will be drilled and the drill bit will be broken when it is severe.
4) The clamping length of the drill pipe is segmented according to the depth of the drill hole, which is beneficial to increase the processing speed.
5) The coolant is selected from the emulsion and the extreme pressure additive. The cooling should be sufficient. If the abnormal sound is heard, the drill bit should be withdrawn. Otherwise, the drill bit will be easily broken.
The measured data stream of the measured gear is equally phase-sampled to form a new measured data stream, thereby eliminating the existence of the lateral resistance of the measured gear due to the measuring rod, resulting in uneven rotation of the measured gear and cycle with the pitch angle. The systematic error is then smoothed by a digital filtering program.
The measured data after preprocessing enters the main program through the input and output terminal ports set by the subroutine, and then flows into each error processing subroutine for data processing. For example, in the pitch deviation and pitch cumulative error subroutine, use Threshold1DArray to find the pitch angle corresponding to the intersection of the actual tooth profile and the tooth height average circle, and compare it with the nominal pitch angle (360/zc) to find each The deviation of the pitch angle of the tooth on the average circle of the tooth height is converted into the deviation of the pitch. The larger the absolute value of the deviation is taken as the single pitch deviation. Note that the deviation of the pitch has positive and negative points. The pitch deviations are sequentially added, and the difference between the maximum and minimum accumulated values ​​is the cumulative total error of the pitch. Finally, the processing results of each subroutine are returned to the main program and displayed on the front panel in the form of images and values.
LabVIEW provides a rich set of interface control objects that make it easy to design a user interface that is dynamic, intuitive, and easy to use. Use the front panel of the main program as the operation panel of the instrument. The operation panel of the cycloidal gear error detector.
5 Conclusion In the cycloidal gear error detector system, the software that fully applies the virtual instrument is the core technology of the instrument and LabVIEW's rich resource library, which reduces the hidden time cost of the test and greatly improves the efficiency of design and development. Through the production application practice, the system has good reliability, operability, high detection accuracy, good maintainability, and easy modification and expansion.
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