Riassunto analitico
In this elaborate the assembly process of the cylinder head covers of a high-performance Ferrari 3.0L V6 engine is investigated. Initially, the research provides an overview of the engine’s most important features to contextualize its market position and the engineering decisions shaping its design. Subsequently, the thesis more deeply analyses the valvetrain system, with particular attention in the valve springs and levers, given their critical role in the definition of the assembly process of the upper parts of cylinder head. In way to better understand the project environment, the industrial assembly process of the engine is summarized, with particular attention on the principal “make” components of the engine.
The key object of the study is to define the assembly procedure of the cylinder head cover: a crucial structural component of the engine with in-built camshaft bushings. A critical aspect in the process definition is the design choice of integrating camshaft bushing supports in the casted aluminium structure of cylinder head cover. This avoids applying a preload on valve springs by mounting the camshafts before the cylinder head cover, thus requiring the compression valve springs while approaching the cover to the cylinder head.
Since only some of the valves must be engaged during the assembly, a mounting fixed position was defined for the camshafts, in way to ensure a pre-determined valve lift pattern. This allowed a study of the asymmetric loads exerted on the component by the compression of the valve springs, leading to the calculation of the resultant force applied to the cylinder head cover in relation with the distance between the components. The main limitations of the possible assembly scenarios are inherent in the industrial plant structure and in the properties of silicone sealant, especially about curing time and contact boundaries.
Further analysis of the component and of the assembly conditions prescribed in technical drawings leads to the development of two different equipment concepts aimed at efficiently accessing the most robust assembly process. The first prototype is acting through a lever mechanism with a position control approach, while the second one is based on threaded connection with torque-force relation in way to obtain an objectivation of the contact.
Finally, a novel assembly concept is proposed, with the elimination of any specific equipment. Basing on a detailed analysis of forces, a new tightening strategy is defined with the aim of balancing the reactant force of the springs simply with a defined tightening pattern/torque strategy. This new approach showed to ensure precise component placement, while promising big improvements in cycle time, cost, and equipment efficiency.
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