THE CONCEPT OF KINEMATIC PAIRS OF QUASI-HIGH CLASSES AND THEIR USE IN ELIMINATION OF REDUNDANT LINKS IN ARTICULATED MECHANISMS

The creation of mechanisms free from redundant links in them is one of the most urgent tasks of modern engineering. Planar articulated mechanisms are most widely used in the practice of mechanical engineering. In his work “Mechanisms in modern technology” Academician I.I. Artobolevsky described more than two thousand mechanisms, at least 70% were planar ones with redundant links in their chains. The appearance of redundant links in the articulated mechanisms leads to a decrease in the efficiency, contributes to the wear of parts in their joints, and reduces the service life of machines. The main direction in mechanical engineering should be the direction of creating adaptive, self-aligning (not containing redundant links) machines. To date, the method for eliminating redundant links proposed by L.N. Reshetov has been thoroughly studied. However, this technique makes it possible to determine only the total number of classical kinematic pairs of the fifth, fourth and third classes to satisfy the condition of the absence of redundant links in the articulated mechanisms. In this paper, we consider the issue of using such kinematic pairs that can provide the required displacement (or rotation) in the desired direction only by a certain predetermined insignificant amount. Such pairs should be called kinematic pairs of a quasi-high class, that is, close in possible movements to classical pairs of high classes. This approach to solving the problem of eliminating redundant links in articulated link mechanisms, which are widely used in the metallurgical industry, will significantly improve the operation of the rolling and clamping mechanisms of the mold, the movement of tables of medium and large-section mills, flying shears, actuators of forging and stamping machines, etc. 

1. Машины и агрегаты металлургических за-водов. В 3-х т. Т. 1. Машины и агрегаты доменных цехов / Ф.К. Иванченко, М.А. Тылкин, А.А. Королев и др. – М.: Металлургия, 1987. – 440 с.

2. Артоболевский И.И. Теория механизмов и машин. – М.: Наука. Гл. ред. физ.-мат. лит., 1988. – 640 с.

3. Uicker J.J., Pennock G.R. Theory of Mechanisms. – New York: Oxford Univ. Press, 2003. – – 928 p.

4. Родионов Н.А. Исследование долговечности подшипников шарнирно-рычажного механизма качения кристаллизатора МНЛЗ. – В кн.: Современное машиностроение. Наука и образование. Материалы 3-й Междунар. науч.-практ. конференции / Под ред. М.М. Радкевича, А.Н. Евграфова. – СПб.: изд. Политехн. ун-та, 2013. С. 371 – 378.

5. Живаго Э.Я. Основные принципы классификации и создания кинематических пар. – В кн.: Труды Междунар. Науч.-техн. конференции. Вопросы проектирования, эксплуатации технических систем в металлургии, машиностроении, строительстве. Ч. II. – Старый Оскол: 1999. С. 142 – 144.

6. Butcher E.A., Hartman C. Efficient enumeration and hierarchical classification of planar simple-jointed kinematic chains: Application to 12- and 14-bar single degree-of-freedom chains // Mechanism and Machine Theory. 2005. Vol. 40. No. 9. P. 1030 – 1050.

7. Евграфов А.Н., Петров Г.Н. Расчет геометрических и кинематических параметров пространственного рычажного механизма с избыточной связью // Проблемы машиностроения и надежности машин. 2013. № 3. С. 3 – 8.

8. Евграфов А.Н., Терешин В.А., Хростицкий А.А. Геометрия и кинематика пространственного шестизвенника с избыточными связями // Научно-технические ведомости СПбГПУ. 2011. № 2. С. 170 – 176.

9. Евграфов А.Н., Хростицкий А.А. Терёшин В.А. Особенности задачи исследования геометрии механизма с избыточными связями // Научно-технические ведомости СПбГПУ. 2011. № 135. С. 122 – 126.

10. Хростицкий А.А., Евграфов А.Н., Терё-шин В.А. Методика силового расчета парадоксальных механизмов с избыточными связями. – – В кн.: XL Неделя науки СПбГПУ. Материалы междунар. науч.-прак. конференции. Ч. IV. – СПб.: изд. Политехн. ун-та, 2011. С. 136 – 138.

11. About preparation of new section of terminology IFToMM on MMS: Chapter 16 “Compliant Mechanisms” / N.T. Pavlovic et al. – In book: Terminology for the mechanism and machine science: Proceedings of the Scientific Seminar (Saint-Petersburg, Russia, June 23-29, 2014). 25th Working Meeting of IFToMM Permanent Commission on MMS. – Gomel – Saint-Petersburg, 2016. P. 47 – 49.

12. Audi R. The Cambridge dictionary of phi-losophy. – Cambridge University Press, 1999. – 1031 p.

13. Boegelsack G. Twenty-five years IFToMM Commission A “Standardization of Terminology” – history, methodology, results and future work // Mech. Mach. Theory. 1998. Vol. 33. No. 1/2. P. 1 – 5.

14. Khurmi R.S., Gupta J.K. Theory of ma-chines. – Ram Nagar, New Delhi, India, 2011. – 1071 p.

15. Saura M., Celdran A., Dopico D., Cuadrado I. Computational structural analysis of planar multibody systems with lower and higher kinematic pairs. Mechanism and Mashine Theory, 71. – Elsevier, 2014. P. 79 – 92.