No description available.

No description available.

No description available.

No description available.

Precision cold forming process modelling, thermal contact conductance and optimum shrink-fitted die with profiled interference were studied. The aims of this work have been achieved using analytical, numerical and experimental approaches to the relevant subjects. Several features of the work are presented: (i) an application of systematic modelling IDEFO language, (ii) an equivalent asperity of surface that enables FE simulation of surface deformation and (iii) a shrink-fitted die with profiled interference, which enables compensation for component-error and necessary die surface pre-stresses. Cold forming process was modelled systematically by IDEFO language in general. The most often used iterations, including design and error-compensation procedures, were constructed; basic activities, inputs, resources and constraints were defined and decomposed. These provide a general procedure for precision cold forming design and a base for the following research of this work. A thermal contact conductance (h -value) experimental investigation was conducted based on steady-temperature measurements and devices. h -value as a function of surface texture and interfacial pressure was experimentally investigated; typically, the value changes from 10 kWm⁻²K⁻¹ to 150 kWm⁻²K⁻¹ for changes in surface texture from Ra = 0.3 0.5 , um to Ra =3-5, um , depending on interfacial pressure (<180 MPa). Based on surface measurements and mathematical work, an equivalent asperity for isotropic surface was presented to represent surface geometry. Uniqueness of the equivalent asperity enables simulation of surface deformation by FE technology. Surface textures under interfacial pressure up to 300 MPa were successfully predicted by FE simulations, results being in agreement with surface measurements. h -value is defined as a function of either contact area ratio or local interfacial pressure; a FE model and an approach of integration of local h -value were dev eloped; value of h was successfully predicted by the established FE model and integration. A profiled interference for shrink-fitting die was designed for component-errors compensation and die surface pre-stress. This was achieved by considering the relationship between die pre-deflection and the profiled interference by FE simulations and a minimisation procedure. Both, the equation and minimisation procedure to determine the profiled interference were established analytically. Uniform die surface direct compensation is combined with shrink-fitted die. Component-errors can be controlled to within a few microns.

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No description available.

No description available.

A new manufacturing process has been developed for reducing the diameter of one end of a tinplate can by over 30%. Conventional processes are limited to a maximum of 10% reduction and typically operate at less than 5%. The improvement was achieved by using special tooling and ultrasonic excitation of the die to reduce the forming force. Ultrasonics have been used in this way before but without a full understanding of the numerous modes of vibration of the die, and how they interact, the efficiency of earlier systems was low. Finite element analysis has been used to characterize the natural modes and frequencies of radial-mode ultrasonic dies and this has led to the development of highly efficient systems. In special cases a non-round die has been required to overcome undesirable modal characteristics; optimum shapes have been developed. A completely new method of mounting the ultrasonic dies was designed and its geometry optimized (again using finite element analysis) to further improve the efficiency of the system. The new system operates at an amplitude under load approximately three times greater than the earlier equipment. The reduction in forming force (between 30 and 60%) makes the difference between success and failure for the manufacturing process.

The thesis is concerned with the conception and design of a FLEXIBLE MANUFACTURING SYSTEM (FMS) for the automation of the manufacture of lawnmower cutting cylinders at Suffolk Lawnmowers Ltd. A review of FMS definitions, planning methods and current systems is carried out for the development of a suitable FMS configuration for the final stages of manufacture of grass cutting cylinders having 21 different design specifications. This involves examination of the capabilities of robotics and microcontrollers to automate the technologies used in cylinder production. The company's current manual batch production system is analysed to determine the suitable form and requirements of the FMS. This includes analyses of annual volumes, throughputs, batch sizes, product and process mixes. Long term objectives to automate the system are identified from which short term objectives are derived. The FMS recommended for immediate development encompasses the short term objectives for the welding, hardening, grinding and transfer processes of 8 cutting cylinder specifications. It is shown that the MIG (Argon/C02) are welding, progressive flame hardening and wide-face cylindrical grinding processes can be developed successfully to automate cylinder production. The recommended system integrates these processes into an FMS through the'automatic handling of cylinders (through three process routes) by a robotic manipulator utilising a double gripper. 'A robotic welding station, manually loaded, is also recommended. ' The system is controlled overall by a 32K microcontroller with the process machines individually controlled by programmahle logic controllers with up to 6K of memory each. The economic appraisal of the FMS indicates a 4.4 year payback based on direct labour and material cost savings. The company's application for grant aid to implement the FMS design has led to an offer of a Department of Industry grant to cover 50% of all capital and revenue costs. The grant of £166,943 reduces the payback period to 2.3 years.