2014-15

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Browsing 2014-15 by Subject "Abrar Ahmed A"

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    Design Of Auto Drilling Mechanism For Dynamic
    (2015-12-23T13:34:36Z) Abrar Ahmed, A; Adil Asharaf, K; Aswin John, Cherian; Mahesh, Madhavan
    Unbalance is the most common source of vibration in machines with rotating parts. Unbalance exists in a rotor when the mass centre axis is different to its running centre axis. Practically all newly machined parts are non-symmetrical due to blow holes in castings, parts fitted off-centre, machined diameters eccentric to the bearing locations etc. An unbalanced rotor, when rotating, wants to revolve around its mass centre axis. Because the bearings restrict this movement, the centrifugal force due to the unbalance causes the rotor to vibrate. This vibration causes wear to the bearings, creates unnecessary noise and in extreme cases disintegration of the rotor itself can be experienced. It is therefore necessary to reduce the unbalance to an acceptable limit. The aim of rotor balancing is to achieve satisfactory running when installed on site. To identify the position and amount of unbalance, balancing machines are used to correct any unbalance that exists. To correct the unbalance material removal by drilling is preferred. After measuring the unbalance, the software calculates the depth of cut that the machine must drill in order to compensate the unbalance. The balancing machine indicates the operator how much material to remove from each lobe (claw) of the rotor. The operator does not have to calculate or vector this amount himself. Based on the specifications, the balancing machine will display the amount to be removed from each lobe of the rotor. The main objective of the present work is to develop and implement a mechanism to drill the holes automatically by using limit switches and timer pulley arrangement so that the drill depth is accurate and the operator can successively operate three machines instead of one thereby reducing the cycle time for balancing operation. This increases the production rate, reduces rework and increases the profit to the company. In the current scenario, the operator manually places the rotor on to the drilling machine and adjusts the depth of cut as specified on the balancing machine using the scale provided on the drilling machine operated by a timer pulley arrangement. A hole is drilled on the lobe where unbalance exists and the operator continues the same until the required depth is achieved. Therefore by automating the drilling operation, an accurate drilling is obtained in addition to the benefits of reduced rework and cycle time for each operation, which ultimately leads to an increase in the production rate.