Stress and Fatigue Analysis of Picking Device Gears for a 2.6 kW Automatic Pepper Transplanter

A seedling picking device is an essential component for an automatic transplanter to automatically convey the seedling to the dibbling part. It is necessary to find the appropriate material and dimensions for the picking device gears to avoid mechanical damage and increase their durability. Therefore, the objectives of this research were to analyze the stress of a picking device gear mechanism in order to select suitable materials and dimensions, and to predict the fatigue life by considering the damage level. The picking device gear shaft divided the input power into two categories, i.e., crank and cam gear sets. Finite element analysis simulation and American Gear Manufacturers Association standard stress analysis theory tests were conducted on both of the crank and cam gear sets for different materials and dimensions. A test bench was fabricated to collect the load (torque) data at different gear operating speeds. The torque data were analyzed using the load duration distribution method to observe the cyclic load patterns. The Palmgren–Miner cumulative damage rule was used to determine the damage level of the picking mechanism gears with respect to the operating speed. The desired lifespan of the transplanter was 255 h to meet the real field service life requirement. Predicted fatigue life range of the picking mechanism gears was recorded as from 436.65 to 4635.97 h, making it higher (by approximately 2 to 18 times) than the lifespan of the transplanter. According to the analyses, the “Steel Composite Material 420H carbon steel” material with a 5 mm face width gear was suitable to operate the picking device for a 10-year transplanter service life. The analysis of stress and fatigue presented in this study will guide the design of picking device gears with effective material properties to maintain the recommended service life of the pepper transplanter.

Nonlinear Dynamic Analysis of a Trochoid Cam Gear

A trochoid cam gear (TCG) is a kind of precise transmission device with high performance, such as non-backlash, high-precision, low noise, etc. However, the nonlinear dynamics has not been studied. In the present paper, the nonlinear dynamic differential equation of the TCG is constructed. First, the trochoid equation and the tooth profile equation are deduced to satisfy the conditions of the continuous transmission. Second, a pure torsional nonlinear dynamic model is established to further construct the nonlinear model of the TCG according to a Lagrange equation. Finally, the dynamic characteristics of the TCG are investigated. For the short amplitude coefficient K, break of quasiperiodic torus is the main reason for the chaotic vibration. By increasing K, the performance of TCG can be improved to maintain stable motion.

Improved Design of Driller Based on the Variable Drilling Speed Damping Mechanism

To improve the driller design using the variable drilling speed technology, by attaching to the cam gear mechanism on the driller spindle, adding a mandatory axial vibration to the driller. The vibration of the drilling speed at a certain waveform and within the scope of a certain amplitude of periodic change, in order to achieve the purpose of reducing the radial drill cutting chatter, ensuring processing quality of hole. Based on variable ​​cutting speed technology and the use of vibration damping mechanism, a variable speed apparatus and a cam gear are attached to achieve a vibration damping, to improve hole drilling parts dimension, shape and position of the precision of the accuracy.

The Optimization Design of High Precision Long-Range Cartesian Coordinate Robots’ Drive System

At present, Cartesian Coordinate Robot driving systems have several ways, such as timing-belt, screw, rack-pinion and chain. But, they are difficult to synchronously meet needs of high precision, long range and heavy load. In this paper, Trochoid Cam Gear (TCG) was used as main transmission mechanism to implement high precision and long range motion of the secondary girder of a Cartesian Coordinate Robot, and disposed reasonably the space positions of linear rails and servo motors to meet the needs of heavy load.

Effects of Eccentricity on Transmission Errors of Trochoidal Gears

This article deals with the effects of eccentricity on transmission errors of trochoidal gears (consisting of a roller gear and cam gear). For the tests, three types of roller gears and three types of cam gears (which had different eccentricity) were used. The experimental results showed that the peak to peak values of transmission errors had a tendency to be greater under a larger eccentricity. The measured transmission error waveforms fluctuated with periods 1/fr, 1/fc and 1/zrfr (in which fr and fc are the rotational frequencies of the roller gears and cam gears, while zr is the number of rollers). The peaks with nfr (n = 1, 2, 3, …), nfc, nzrfr, nzrfr ± mfr (m = 1, 2, 3, …) and nzrfr ± mfc appeared in the measured transmission error spectra. The amplitudes of peaks with fr and nzrfr ± mfr increased as er increased, while the amplitudes of peaks with fc and nzrfr ± mfc increased as ec increased. The transmission errors of test gears with eccentricity were estimated by the multibody analysis (MBA). A reasonable correlation exits between the calculated results obtained by the MBA and the measured experimental results.