Building Drum Speed Control via PWM for Tire Conformation

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Solution Overview

Problem

Existing methods for building tires using elementary semifinished products face challenges in precision and accuracy due to limitations in controlling the revolution speed of the building drum, particularly when the desired speed is not an integer value, leading to uneven tire conformation and performance issues.

Innovation Solution

A method and working station that utilize an anthropomorphic robotized arm with a control apparatus to determine a target speed for the building drum, calculate a PWM profile for non-integer speed values, and apply it over a short drive interval to precisely control the drum's rotation, ensuring accurate tire component formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the building drum rotation speed is controlled using integer values only, then the control system is simple, but the tire conformation precision deteriorates

Engineering Contradiction:

Improvecontrol system complexityVSAvoidtire conformation precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent changes the speed control parameter from discrete integer values to continuous values through PWM modulation. The control system now accepts non-integer speed values (e.g., 1.5 Hz, 2.3 Hz) by converting them into pulse width modulated signals that adjust the motor drive duty cycle, enabling precise speed control while maintaining system simplicity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic speed adjustment capability where the building drum rotation speed can be continuously varied during operation. The PWM control allows real-time modification of the motor drive signal width, enabling the system to adapt the rotation speed dynamically to achieve precise tire conformation without being constrained by fixed integer steps

Inventive Principle:

Principle #15Dynamics

2Productivity

If the building drum rotation speed is increased to improve productivity, then the production rate increases, but the tire conformation uniformity deteriorates

Engineering Contradiction:

Improveproduction rateVSAvoidtire conformation uniformity

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback control mechanism where the actual building drum rotation speed is monitored and compared against the target speed. The PWM control system adjusts the motor drive duty cycle based on this feedback to maintain precise speed control even at higher rotation rates, ensuring uniform tire conformation is maintained throughout the deposition process

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent uses periodic PWM pulses to control the motor drive, where the duty cycle of the periodic pulses determines the average power delivered to the motor. This periodic action with variable duty cycle allows smooth speed control across a wide range, enabling high productivity while maintaining conformation uniformity through precise average speed control

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS12257795B2Working station for deposition of elementary semifinished products for building tyres

Publication Date: 2025.03.25 PIRELLI TYRE SPA

AI summary

A working station for deposition of elementary semifinished products for building tyres is, the working station includes an anthropomorphic robotized arm for moving an output end effector, a building drum, a feeding apparatus and a control apparatus. The control apparatus is configured to calculate, in a drive interval, a pulse with modulation (PWM) profile for a speed parameter and controlling the output end effector as a function of the PWM.