88218 - Mechanical Drives P

Learning outcomes

The student acquires basic knowledge about: the operation and modeling of advanced mechanical components used in machines; modelling, analysis and synthesis problems related to motor-user coupling; pneumatic components and circuits.

Course contents

POWER TRANSMISSION DEVICES

1. Couplings, clutches and brakes.

• Rigid, compliant and mobile shaft couplings.
• Positive-contact and friction mechanical clutches. Overrunning clutches (freewheels). Fluid couplings.
• Disk, drum and band mechanical brakes.

2. Power transmission devices with variable transmission ratio.

• Motion laws with periodic transmission ratio. The motion law and its properties: velocity, acceleration and torque coefficients. Criteria for the choice of the displacement function: limitation of velocity, acceleration and driving torque. Qualitative comparison between displacement functions.
• Planar linkages. RRRR, RRRP and RRPP kinematic chains. Special positions: stationary and singular configurations. Coupler curves. Dwell mechanisms and force amplifiers. Quick-return mechanisms. Mechanisms for linear and translatory motions.
• Intermittent-motion mechanisms: Geneva mechanisms, indexers.

CONNECTION BETWEEN DRIVING AND OPERATED MACHINES

5. Dynamics of a single-degree-of-freedom machine.

− Equation of motion. Energetically-equivalent reduced machine. Steady-state operation. Steady-state torque-speed characteristics of driving and operating machines. Speed regulation.

6. Choice of the motor/reducer group.

• Choice of the electric motor: the thermal problem, duty cycles, influence of the start-up transient. Selection and verification of the brake. Selection and verification of the clutch. Selection and verification of the gear reducer: service factor, peak torque, radial and axial loads, bearing reactions.
• Selection and verification of gearmotors for static loads and single-speed operations. Selection and verification of gearmotors for periodic steady-state operations: criteria of maximum and root-mean-square torques. Limitation of nonuniformity: the flywheel.

FUNDAMENTALS OF PNEUMATIC POWER TRANSMISSIONS

8. General principles and components.

• Fluid transmission of power. Main components of pneumatic circuits.

9. Pneumatic circuits.

10. Safety

11. Electrovalve island integration

Readings/Bibliography

1. LEZIONI DI MECCANICA APPLICATA ALLE MACCHINE, Parte II: Elementi di Meccanica degli Azionamenti. E. Funaioli, A. Maggiore, U. Meneghetti. Pàtron Editore, 2009 (testo principale del corso).
2. MECCANISMI PER MACCHINE AUTOMATICHE. P.L. Magnani, G. Ruggieri. Utet, 1986 (testo di approfondimento consigliato per la tematica "Trasmissioni a rapporto di trasmissione variabile").
3. MECCANICA DEGLI AZIONAMENTI, Vol. 1: Azionamenti Elettrici. G. Legnani, M. Tiboni, R. Adamini, D. Tosi. Ed. Esculapio, 2008 (testo di approfondimento consigliato per la tematica "Accoppiamento motore-utilizzatore").
4. MANUALE DI PNEUMATICA. G. Belforte. Ed. Tecniche Nuove, 2005 (testo di approfondimento consigliato per la tematica "Fondamenti di pneumatica").

Teaching methods

Classes are based on theoretical lectures with application examples.

Assessment methods

The examination is based on an oral interview.

According to the University Regulations, each examination determines a positive or negative evaluation. A positive assessment involves the assignment of a numeric grade equal to or greater than 18/30. A negative assessment does not result in a numeric grade, but in a descriptor (i.e. withdrawn or rejected) reported on the examination record. The negative evaluation is not included in the student academic record and it does not affect the average score that determines her or his final degree grade.

If a positive grade does not meet the expectations of a student, the latter may ask its cancellation and the repetition of the examination. The instructors of the course Complements of mechanical drives P comply, in general, with the following rules:

• a student may request the cancellation of a positive grade only within the date specified in the public communication of the examination outcome;
• a cancelled positive grade can in no way be recovered;
  
• a student may request the cancellation of a positive grade at most once.

Teaching tools

On the E-learning Platform, students may find:

- slides of the course lectures;
- exercises and application examples.

Office hours

See the website of Marco Carricato

See the website of Michele Ferrari