Method of manufacturing a foam buffing pad of string-like...

Abrasive tool making process – material – or composition – With rubber or reaction product thereof

Reexamination Certificate

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Details

C451S527000, C451S528000, C451S532000

Reexamination Certificate

active

06312485

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention pertains to the field of foam buffing and pads. More specifically, the invention is a rotary pad made from foam string material for buffing and polishing painted or similarly finished surfaces.
Foam buffing pads are now used in many buffing and polishing operations where synthetic or natural fiber pads, such as tufted wool pads, had previously been used. In particular, open cell polyurethane foam pads, with both reticulated and non-reticulated cell structures, have become particularly popular. However, despite certain advantages of polymer foam pads over fibrous and tufted pads, there are still a number of inherent disadvantages attendant the use of foam pads. These disadvantages include the “chatter” or jumping of the pad by excess frictional surface contact between flat working surface portions of the pad and the surface of the work being finished; splattering of the polish or other finishing compound as a result of the compound being thrown radially outwardly by centrifugal force; and, burning of the surface of the work being finished by the high speed outer edge portions of the rotary pad.
Attempts have been made to minimize or eliminate these problems by varying the type and density of foam used and by changing the working surface of the pads. Initially, foam pads were made of a generally cylindrical disc with a flat planar working face and, typically, with a radiused outer edge providing the transition between the working face and the outer cylindrical edge face. However, flat pads are particularly subject to chatter and provide little deterrent to the splatter of polish. Flat faced pads also give the operator little control over variations in the working surface actually in contact with the work surface being finished or polished. One attempt at solving the problems presented by flat foam buffing pads was the introduction of buffing pads having working surfaces with a convoluted or waffle shape. One such pad was previously made by Lake Country Manufacturing, Inc. Although this pad provided variable working surface contact by varying operator-applied pressure, surface contact was somewhat difficult to control and the pad did little to prevent splatter. A different approach to solving the prior art problem is shown in U.S. Pat. No. 5,527,215 where a cylindrical foam pad has a recessed center portion or portions within which the polishing compound may be trapped against radial splatter. This pad also provides the ability the alter the working surface contact by varying operator-applied pressure. However, neither of the foregoing pads adequately solves all of the prior art problems.
One recent attempt to solve the remaining problems inherent in foam buffing pads has resulted in the introduction of a pad having a working face comprising a concave central contact surface which increases radially inwardly with increasing pad compression by the operator. This pad has helped reduce chatter and improved operator control of the working surface contact area.
However, all of the foregoing foam pads are characterized by their monolithic body construction in which the foam bodies are made of a single uniform layer of foam material and, as a result, have an uninterrupted working face regardless of variations in face contour. As a result, monolithic polymeric foam pads remain subject to pad chatter, relatively rapid working surface contamination, undesirable swirl marks, and susceptibility to tearing out of large pieces of the foam body as a result of contact with obstructions during finishing operation.
Therefore, foam buffing and finishing pads have never completely replaced pads made with tufted wool fibers or other natural or synthetic fibers. U.S. Pat. No. 2,690,661 shows an attempt to provide a hybrid pad comprising a tufted construction of cotton strands to which an outer layer of cellulose material is intimately bonded. If a pad of this construction was ever commercialized, its use today is not known.
SUMMARY OF THE INVENTION
In accordance with the present invention, a surface finishing pad and its method of manufacture are provided which combine all of the best features of foam pads and tufted pads and, as a result, provide a pad capable of providing a superior finish, substantially extended wear life, superior performance, and substantially extended service time between cleanings.
In a preferred embodiment of the invention, a surface finishing pad includes a support substrate and a plurality of fingers of polymeric foam material with the fingers having outer tips which define a pad finishing surface. The fingers may be joined to the support substrate in one of several manners. In the presently preferred embodiment for use as a rotary finishing pad, the support substrate is circular. Preferably, the support substrate is formed from a plastic material having a plurality of openings.
The polymeric foam material preferably comprises polyurethane. More preferably, the material is an open cell polyurethane which may or may not be reticulated. The outer tips of the fingers may be loaded with an abrasive material, such as abrasive particles. The abrasive particles may be adhesively attached to the fingers or may be incorporated directly into the foam material.
In a presently preferred embodiment of the subject invention, a surface finishing pad comprises a support substrate and a plurality of individual fingers of polymeric foam disposed i the support substrate. Each of the foam fingers has an attachment portion that extends through the substrate and is affixed to the back face of the support substrate. Each of the fingers includes an outer tip that extends from a front face of the support substrate, such that the outer tips of the fingers define the pad finishing surface. Preferably, the surface finishing pad is formed from a plurality of individual foam members that are disposed in a dense array on the support substrate.
Each of the foam members includes a first outer tip and a second outer tip. The foam member is folded along an attachment portion positioned between the first and second outer tips. The attachment portion of each foam member is pressed through the support substrate such that the attachment portion of the foam member extends from the back face of the support substrate. In the preferred embodiment of the invention, the attachment portion is adhesively attached to the back face of the support substrate.
In a preferred embodiment, each of the first and second outer tips of the foam member includes a pair of slits extending into the body of the foam member from the respective outer tip. The pair of slits divide each of the outer tips into four contact tips, thereby increasing the amount of surface contact between the surface finishing pad and the painted surface to be finished.
One embodiment of a method for manufacturing a surface finishing pad, in accordance with the present invention, includes the steps of (1) providing a support substrate having a front face and a back face, (2) forming a plurality of individual foam members each having a first outer tip and a second outer tip, (3) folding each of the foam members to form an attachment portion between the first and second outer tips, (4) pushing the attachment portion of each foam member through an opening in the support substrate, and (5) securing the attachment portion to the back face of the support substrate. The foam members may be attached to the support substrate by an adhesive layer, a series of staples, the friction fit between the foam members and the support substrate, or an equivalent method.
Additionally, the method of manufacturing the surface finishing pad can include the step of slitting the outer tip of each foam finger along a pair of orthogonally disposed slit lines. After each outer tip has been slit, each outer tip will include a plurality of contact tips that can be used in surface finishing.
In accordance with a particularly preferred method of manufacturing a surface finishing pad, the steps include (1) providing a continuous strip of polymeri

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