Dynamic performance improvement like less vibration, smooth motor torque requirement, etc. of a carpet scrappingmachine to enhance productivity and quality of Indian hand knotted carpets is presented. A complete dynamic analysis is carried out, along with optimum balancing of shakingforce and shaking moment of the machine. To do this, its inertia properties are re presented by dynamically equivalent systems, referred as equimomental systems,of point-masses to identify the design variables, and formulate the associatedconstraints. Mass redistribution and counterweights are suggested methods to improve dynamic performances of existing carpet scrapping machine.

Key words: Carpet Scrapping machine,Dynamic performances, Optimization, Shaking force, Shaking moment.

1 Introduction

Carpet weaving is facing a toughcompetition from other exporting countries of Asia-Pacific region due to marketliberalization (1). A project (1, 2) with the aims to improve processes, tools and machines involved in the manufacturing of carpets was initiated by IIT Delhi in 2000. In the project, optimisation of a metallic loom (3) was carried out for itsreduced weight and cost. A way to balance any mechanism is to trade-off betweenall the competing dynamic quantities (4-10). Since shaking force, shaking moment,input-torque, etc., depend on the mass and inertias of each link, and its mass centrelocations (8), it is required to optimally distribute the link masses fordynamic balancing. A convenient way to represent the inertia properties of the links is treating them as dynamically equivalent systems of point massesreferred to as equimomental system (11). Using the concept ofequimomental system, Sherwood & Hockey (8) presented optimization of massdistribution in mechanisms. Using the two point-mass models, Wiederrich &Roth (9) presented momentum balancing of four-bar linkages. Optimum balancingof combined shaking force, shaking moment, and torque fluctuations in linkageswas later reported in Lee & Cheng (10), where a two point-mass model was used.In this paper, concept of equimomental system is used to balance the carpet scrappingmachine in order to minimize shaking force and shaking moment so that vibrationsand fluctuation in driving torque are reduced. Two methods are presented; the first is for the design of new scrapping machine using mass redistribution movinglinks and the second for reducing the unbalance of an existing one using counterweights.The methodology is quite general and not restricted only to singleloop four-barlinkage as reported in Refs (9, 10, 13). The dynamic analysis presented in Ref (13) is extended in this paper for Carpet scarping mechanism which is amultiloop mechanism.


Read FullArticle

Aboutthe Authors

The authorsare associated with Department of Mechanical Engineering, MLV Textile and Engineering College, Bhilwara and IIT Delhi, New Delhi, India, respectively.