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The kinematic design of a planar-cam type pick-and-place device
Wen-Tung Chang,Long-Iong Wu,Chun-Hsien Liu 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.12
The planar-cam type pick-and-place device can clearly and effectively achieve the desired curvilinear motion of its end effector, and it can be designed and fabricated easily. By employing the concept of velocity instant center, the cam profiles, the paths of cutters, the pressure angles and the radii of curvature of the dual cams of the planar-cam type pickand- place device can be expressed parametrically. The cam profiles may have concave portions, and each minimum radius of curvature of the concave portion of the dual cam profiles is the upper bound of the grinding-wheel radius that may not cause undercutting.
Mechanical Error Analysis of Disk Cam Mechanisms with a Flat-Faced Follower
Wen-Tung Chang,Long-Iong Wu 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.3
By employing the concept of equivalent linkage, this paper presents an analytical method for analyzing the mechanical errors of disk cam mechanisms with a flat-faced follower. The resulting error equations do not really involve the location of the curvature center of the cam profile, and locating the curvature center of the cam profile is not essential. The resulting errors are significantly affected by the pressure angle, and the smaller pressure angle will result in the smaller mechanical error. In the worst case, owing to the joined effects of various design parameters, the accuracy of the follower motion may degrade considerably. For the oscillating follower case, all acceleration error functions have a sudden change at every beginning and at every end of the motion even though the theoretical follower displacement is cycloidal motion.
Wen-Tung Chang,Sheng-Yan Lu,Shui-Fa Chuang,Geo-Ry Tang,Fang-Jung Shiou 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
In this paper, an optical-based method and system for measuring web thickness of microdrills considering runout compensation is introduced. The presented measuring method is a nondestructive and noncontact means based on the use of an optical micrometer (OM) and a surface scanning laser confocal displacement meter (LCDM). The OM is used to determine the runout amount and the cross-sectional outer diameter of the microdrill, and the surface scanning LCDM is used to scan the cross-sectional profile of the microdrill to further determine its dual cross-sectional flute depths with runout-related deviation amounts being excluded. Then, the cross-sectional web thickness of the microdrill is calculated through the difference between the determined cross-sectional outer diameter and dual cross-sectional flute depths. An optical-based measuring system, for implementing the presented method, was constructed. Experiments meant to measure web thickness of microdrill samples were conducted. It showed that the presented measuring method, combined with the constructed measuring system, was feasible for the runout compensation of the web thickness measurement for certain microdrills.
Calculating actual profiles of conjugate disk cams by means of conjugate variation measurement
Wen-Tung Chang,Long-Iong Wu 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.12
For an assembled conjugate cam mechanism with two separate oscillating roller followers serving as a conjugation measuring fixture,when the cams rotate, the variation of the subtending angle between the two follower arms can indicate the variation of the cam profile errors. The profile errors of the assembled conjugate disk cams can be indirectly calculated by means of the conjugate variation measurement and the inverse conjugate variation analysis. That is, if a pair of master conjugate cams with known profile errors is available, by means of the measured subtending angle variations of the follower arms induced by a pair of assembled conjugate cams that consists of one master cam and the other being the inspected cam, then the actual profile of the inspected cam can be calculated by applying the inverse conjugate variation analysis. In order to verify the presented concept, experiments meant to calculate the profile errors of a pair of machined conjugate cams were conducted to compare with the measuring results obtained by using a coordinate measuring machine. The experimental results showed that the calculated cam profiles were well consistent with those of the measured ones. The presented method can be an effective alternative means for examining profile errors of assembled conjugate disk cams and could be useful for the quality control in mass production of conjugate cams.
Mechanical Error Analysis of Disk Cam Mechanisms with a Flat-Faced Follower
Chang Wen-Tung,Wu Long-Iong The Korean Society of Mechanical Engineers 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.3
By employing the concept of equivalent linkage, this paper presents an analytical method for analyzing the mechanical errors of disk cam mechanisms with a flat-faced follower. The resulting error equations do not really involve the location of the curvature center of the cam profile, and locating the curvature center of the cam profile is not essential. The resulting errors are significantly affected by the pressure angle, and the smaller pressure angle will result in the smaller mechanical error. In the worst case, owing to the joined effects of various design parameters, the accuracy of the follower motion may degrade considerably. For the oscillating follower case, all acceleration error functions have a sudden change at every beginning and at every end of the motion even though the theoretical follower displacement is cycloidal motion.
Chen, Wen-Kwei,Liu, Ingrid Y,Chang, Ya-Ting,Chen, Yong-Cyuan,Chen, Chih-Cheng,Yen, Chen-Tung,Shin, Hee-Sup,Chen, Chien-Chang The Society 2010 The Journal of neuroscience Vol.30 No.31
<P>Treatments for chronic musculoskeletal pain, such as lower back pain, fibromyalgia, and myofascial pain syndrome, remain inadequate because of our poor understanding of the mechanisms that underlie these conditions. Although T-type Ca(2+) channels (T-channels) have been implicated in peripheral and central pain sensory pathways, their role in chronic musculoskeletal pain is still unclear. Here, we show that acid-induced chronic mechanical hyperalgesia develops in Ca(v)3.1-deficient and wild-type but not in Ca(v)3.2-deficient male and female mice. We also show that T-channels are required for the initiation, but not maintenance, of acid-induced chronic muscle pain. Blocking T-channels using ethosuximide prevented chronic mechanical hyperalgesia in wild-type mice when administered intraperitoneally or intracerebroventricularly, but not intramuscularly or intrathecally. Furthermore, we found an acid-induced, Ca(v)3.2 T-channel-dependent activation of ERK (extracellular signal-regulated kinase) in the anterior nucleus of paraventricular thalamus (PVA), and prevention of the ERK activation abolished the chronic mechanical hyperalgesia. Our findings suggest that Ca(v)3.2 T-channel-dependent activation of ERK in PVA is required for the development of acid-induced chronic mechanical hyperalgesia.</P>
Design of disk cam mechanisms with a translating follower having symmetrical double-concave faces
Yu-Hsuan Chuang,Kuan-Lun Hsu,Wen-Tung Chang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8
This paper presents an analytical approach for designing disk cam mechanisms with an improved translating follower having symmetrical double-concave faces. The doubleconcave faces of such a follower can increase the actual contact area between the cam and the follower. Additionally, during the dwell periods of the follower motion, both the concave faces of the follower can simultaneously contact the cam profile so as to share the carried loading. Such beneficial characteristics can result in a lower level of contact stress between the cam and the follower. Numerical examples are provided to illustrate the nature and the advantage of this improved follower.