Abrading – Precision device or process - or with condition responsive... – Computer controlled
Patent
1993-06-21
1994-11-29
Rose, Robert A.
Abrading
Precision device or process - or with condition responsive...
Computer controlled
451307, B24B 2102
Patent
active
053678354
DESCRIPTION:
BRIEF SUMMARY
This invention relates to polishing apparatus and in particular to such apparatus for polishing the dished heads of processing vessels.
Processing vessels used in industries such as food, pharmaceutical and chemical industries often have the requirement that all contact surfaces must be thoroughly cleanable. This is achieved by polishing the contact surfaces of the vessel. Many such vessels are constructed by rolling prepolished flat plate into a cylinder then welding one dished head on either end and inserting the various necessary inlet/outlet pipes and manways. It is the dished heads of a vessel which incur the greatest time and expense in achieving a finish comparable to that of the rolled sections of the cylinder. Such dish heads have in general always been finished by hand which is very costly and time consuming, as well as dirty, noisy and tedious for the personnel carrying out the work.
The invention seeks to provide an apparatus capable of polishing such dished ends automatically.
According to the present invention there is provided a polishing apparatus which comprises a main arm mounted for movement in horizontal and vertical directions, the arm being provided with a rotating belt of abrasive material for polishing purposes, and means for mounting and rotating a dish to be polished characterised in that the arm carries a mechanism, including a contact wheel, movable relative to the arm along two orthogonal axes and an associated pneumatic cylinder providing biasing force.
The invention further comprises a method of polishing a dished end which comprises placing a dished end in the above apparatus, moving the arm so that one radius of the dished end is followed by the contact wheel, storing the trajectory in memory, raising the arm a fixed amount above the dished end surface, and traversing the arm from the center to the periphery and back repeatedly while the dished end is rotated, pressure being applied to the contact wheel by the pneumatic cylinder in accordance with information stored in the memory.
The apparatus and method of the invention allow dished ends to be accurately polished quickly and simply without resorting to manual methods. The machine may be used for a variety of dished ends of different sizes one after another since in each case it simply "maps" a single radius of the dished end and stores this in memory for the subsequent polishing operation. A unique feature of the invention is that minor irregularities which are bound to occur in such objects as dished ends are compensated for through the "offset" mechanism as described more fully hereinafter.
The mechanism, or "X-Y plate", is movable relative to the main arm in two axes. It is urged towards the surface to be polished and therefore urges the contact wheel carrying the abrasive belt into contact with the surface to be polished, by means of a pneumatic cylinder. The travel of the pneumatic cylinder is arranged such that it has sufficient stroke as to be greater than any of the irregularities in the surface likely to be encountered. This means that although the main arm will follow a fixed path according to the radius stored in memory the X-Y plate, and abrasive contact wheel, can "ride" irregularities while maintaining a constant pressure of the belt on the surface. In this way, the surface is smoothly polished and yet irregularities are allowed for without having to map the entire surface. The fact that only a single radius needs to be "mapped" means that this operation takes only a few seconds rather than many minutes or hours as with certain programmable grinding machines.
It will be appreciated that the apparatus of the invention can also be used for grinding operations, i.e. where the surface finish of the workpiece is initially too rough for final polishing. This may be accomplished by employing successive belts of increasingly fine abrasive material up to and including the final polishing stage. This process is known as "finishing.
The invention will be described further, by way of example, with reference to the accom
REFERENCES:
patent: 2573220 (1951-10-01), Riedesel
patent: 2901871 (1959-09-01), Kluge, Jr.
patent: 3149441 (1964-09-01), Hess
patent: 3488891 (1970-01-01), Kissling
patent: 4886529 (1989-12-01), Hashimoto et al.
Crawford-Swift Limited
Rose Robert A.
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