Investigation of complex surfaces of propellers of vehicles by a mechatronic profilograph

OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. No. 4 2021 – electric motors, (a brushed motor TETRIX® MAX TorqueNADO ® Motor W44260 (12 V, DC with a speed of 100 rpm and a torque of 4.9 Nm) and a stepper motor NEMA 17 42HS48-1684-08AF (rated cur- rent: 1 , 68 A, torque: 5.0 kg/cm, rated voltage: 2.8 V, swing angle / step: 1.8 °) are used); – an accelerometer; – a gyroscope. A stepper motor was chosen to move the carriage, since a high torque is not required, but it is necessary to rotate the console. The housing is mounted on a rack by means of rolling bearings. Fixed support wheel, a satellite and a motor located on the movable housing are used to rotate it. The laptop is connected with the control unit, sensors and electric motors via Bluetooth radio modules built-in into the laser sensor, a control unit and a laptop. To perform a structure consisting of a carriage with a laser position sensor, a guide and a screw, a backlash-free bronze nut with manufacturing accuracy H7 , and a trapezoidal screw with a diameter of 8 mm were used. Moreover, the nut consists of two elements between which a spring is installed. The spring force pushes the elements of the nut away from each other reducing the backlash and the progressive rotation error. The guide, made of T-shaped grooves in an aluminum pro fi le simpli fi es fi xing of the movable carriage during translational movement. Preliminary calculations of the structure strength showed that at a distance of 1 meter with a cantilever mounting of the guide, the deformation grade caused by its own weight is 1.12 mm, and when exposed to a carriage with a sensor weighing 0.15 kg the linear deformation is 1.79 mm. When checking the mechatronic pro fi lograph, these errors are taken into account, and an external inspection, testing, software check and determination of metrological characteristics are carried out. The mechatronic pro fi lograph was tested using a calibration plate. The laser sensor is based on the principle of optical triangulation (the maximum data update rate is 2 kHz, the resolution is 0.01 % of the range), and the angular encoder records the cycle of passage of the magnetic pole of a rotating magnet located near the sensing element. The metrological characteristics of the information and measuring system are established: the measuring range of the distance from the sensor to the surface is 100…500 mm, the limits of the permissible absolute measurement error are ± 0.05 % of the range, the measurement range along the circumference is from 0 to 360 degrees, the limits of the permissible error of the angular encoder are ± 30”. The performance of the mechatronic pro fi lograph: overall dimensions are 1,450x25x550 mm; the change range in the angular velocity of the sensor is 0.1...2.5 rad/s; the change range in the radial velocity of the sensor is 0.0001...0.01 m/s; the supply voltage of the angular encoder of the E60H series is 5 V DC, the current consumption is ≤ 80 mA; the number of pulses per revolution is 1,024…8,192, the operating temperature range is –10...+70 °C, the response frequency is up to 300 kHz. Thus, to implement the pro fi ling of a complex surface, a mechatronic pro fi lograph equipped with an information measurement system is used as a mechatronic measurement system. To pro fi le a complex surface of parts, a mechatronic pro fi lograph is placed on or near the studied surface on a horizontally positioned table, if the part is small. Accelerometer and gyroscope are used to determine accurately the horizontal surface the laser sensor moves on. For example, compact laser sensors were used during the study. Accelerometer and gyroscope are similar in a way and complement each other, increasing the accuracy of the obtained data. The gyroscope is used to track the position of the laser sensor in space by determining its own angle of inclination relative to the Earth surface. The accelerometer at rest allows calculating the angle of inclination relative to the vector of the Earth gravity. The deviation of the rotation surface of the laser sensor from the level in two perpendicular directions is displayed on the monitor screen in digital form. To correct the horizontal position, the rack is de fl ected, achieving zero deviations from the horizontal in the longitudinal and transverse directions. For this purpose, for example, the MPU6050 is used, which is a 3-axis gyroscope and a 3-axis accelerometer in the same housing. First, a pro fi lograph equipped with an information system determines the pro fi le of a complex surface of a part along a circle that limits the area to be measured. For this purpose the program is run on a laptop