2nd ICAI 2022

International Conference on Automotive Industry 2022

Mladá Boleslav, Czech Republic

Clutch design includes two load situations. The first load situation is a clutch engaging. While clutch engaging clutch transfers energy from running drive side to still standing machine side. Energy transfer is accompany by clutch slip where energy is lost - heat generation. Clutch overheating must be controlled. Second load situation is a maximum torque which occurs during forging (technology operation). High forces and torque in machine side occurs with forging technology. 2. Details of a 25MN forging press In following chapters there are friction energy loss calculations. These calculations are all performed for the same press, with the same clutch. Technical description of such press is in Table 1.

Table 1: Technical parameters of the press Nominal pressing force F

25

[MN]

Transmitted torque

M A u

1.75 225 100 7.33

[MNm]

[kJ] [kJ]

Useful work

Kinetic energy of a machine side Angular velocity of the flywheel Number of friction surfaces

E kmech

ω n

[rad/s]

4

[-]

2.1 Empirical approach According to (Kamelander, 2019) the start-up work A start , which is lost during clutch engagement, is approximately equal twice the amount of the braking work. This it because it composes of energy to start-up the mechanism, which is the same as the energy that needs to be withdrawn from the mechanism in order to stop it, and energy ∆E lost by clutch engagement. This energy ∆E is then dissipated in heat. Results of this approach of calculations are valid only for ideal state. In reality the start up work A start is higher due to slippage that occurs while the actuating force is not yet high enough to engage the clutch. 2.2 Analytical approach The clutch in the drive of press typically serves to connect and disconnect the flywheel (A) to the press mechanism (B) (Figure 3). Usually a dry friction air-operated disk clutch is used. Assume that: I A [kg . m 2 ] Moment of inertia – drive side I B [kg . m 2 ] Moment of inertia – machine side ɷ A [s -1 ] Angular velocity – drive side ɷ B [s -1 ] Angular velocity – machine side

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