TECHNICAL ARTICLE 3) Working speed of machine. 4) Maintenance of machine. 5) Design of other machine parts like blowers, ducts and pipes etc. 6) Material handling system. Overview of noise levels in Different departments: 1) Spinning: Because of high spindle speeds reached on new machines (ring spindles up to 20000 rpm, rotor speed up to 11000 rpm) spinning mills can generally be assumed to generate a great noise. Noise levels of 70 to 100 dB are commonly recorded in workrooms. 2) Weaving and knitting: Although considerable progress has been made in the weaving sector over the last 20 year, the whole area of noise nuisance and, closely associated with it, vibration coming from looms, cause major problems. Noise levels of 100 to 120 dB must be expected in weaving rooms, according to the design, type of loom. Fitting and erection and number looms used, fabric structure etc. The following table shows the noise levels in various departments. Table 2: Noise level in textile industry (Texturing, spinning and Weaving) Process
Noise level (dB)
Texturizing Plant
95-100
Spinning 1.Ring Frame
80
2.Rotor spinning
84
3.Two for one twister
100-110
4.Weaving
100-120
Today’s machine scenario against conventional one with respect to noise generation: All modern machines are far differing than conventional one with respect to noise generation. The conventional practice of designing of machines was based on pure mechanical concepts rather than combination of mechanical and electronics, since the development in the electronics industries was not up to the level that today it is. Today we are talking about the automated machines purely based on mechatronics concept and it offers following advantage. 1) Reduction in the mechanical parts and accessories with electronic base mechanisms.
ing machines offers efficient control on various parameters like yarn, fabric tension on spinning and weaving machines, speed control devices, Building mechanism on speed frame and ring frame as it was traditionally based on cam and linkage mechanism etc. Shows pronounced impact on noise reduction. The development in material handling system also offers positive contribution towards noise reduction this is especially while handling of plastic cops during doffing operation similarly beams handling system in weaving unit with monorail arrangement [6]. The handling of spare parts also shows some good correlation with noise level which involves proper storage of parts like boxes and bines etc. The following points show some features of modern machine. Sturdy design of machines Use of minimum number of linkages More focus on mechatronics which relates to minimum number of metallic parts Proper design of Jig & fixer shows reduction in vibration up to 20 dB Use of proper bearings and centralized lubrication system reduces friction Improved metallurgy of metallic parts in other words use of light weight parts Provision of suction systems at various points results in dust reduction by 30-35% Enclosed machine parts minimizes accidental cases by 50% Machines are equipped with safety panels and sensors to sense the abnormalities Design aspects to control the noise: Behavior of sound: When designing engineering control to reduce the noise exposure it is important to have basic understanding of sound and its impact. Sound is always produced by change in the speed or force. Basic principle of sound includes, 1) More noise is produced when great force is used for longer time than small force with shorter time. 2) Airborne sound is caused by vibration of solid parts or turbulence in case of fluid. 3) Vibration can produce sound after traveling a great distance. 4) High frequency sound is more reflective.
2) High and efficient accuracy
5) Low frequency noise is travels through object and through opening.
3) Offers flexibility in the working.
6) Audible range of human ear is up to 80-90 dB.[7]
4)Ease of maintenance.
Design and planning: first step in effective noise control is design and purchase in noise control in mind. Take noise control in account when designing new facilities renovating existing buildings. Isolate noisy operations in design
5) Low mechanical complicity. Also introduction of hydraulics, pneumatics with solenoid valves and PLC operating system on spinning on weav-
December 2017
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