DE20112293U1 - Polishing pad - Google Patents

Description

Eisenführ, Speiser & Partner

Bremen, Our sign:

July 24, 2001

H 3446 MAN/be

Applicant/Owner: HOLBROS LTD.,
Official reference number: New registration

·»· ■· · · · · Hamburg • · · · · eremen · · · Patent Attorney European Patent Attorney European Patent Attorneys Dipl.-Phys. Frank Meier Dipl.-Ing. Günther Eisenführ Dipl.-Ing. Dieter K. Speiser Lawyer Dr.-Ing. Werner W. Rabus Rainer Boehm Dipl.-Ing. Jürgen Brügge Dipl.-Ing. Jürgen Klinghardt Munich Dipl.-Ing. Klaus G. Göken Patent attorneys Jochen Ehlers European Patent Attorneys Dipl.-Ing. Mark Andres Dipl.-Phys. Heinz Nöth Dipl.-Chem. Dr. Uwe Stilkenböhmer Dipl.-Wirt.-Ing, Rainer Fritsche Dipl.-Ing. Stephan Keck Lbm.-Chem. Gabriele Leißler-Gerst Dipl.-Ing. Johannes M. B. Wasiljeff Dipl.-Ing. Olaf Ungerer Patent Attorney Patent Attorney Dr.-Ing. Stefan Sasse Dipl.-Chem. Dr. Peter Schuler Lawyers Berlin Ulrich H.Sander Patent attorneys Christian Spintig European Patent Attorneys Sabine Richter Dipl.-Ing. Henning Christiansen Dipl.-Ing., Joachim von Oppen Martinistrasse 24 Dipl.-Ing. Jutta Kaden D-28195 Bremen Dipl.-Ing. Mathias Karlhuber Tel.+49-10)421-36 35 0 Fax +49-10)421-337 8788 (G3) Alicante Fax +49-10)421-328 8631 (G4) European Trademark Attorney mail@eisenfuhr.com Dipl.-Ing. Jürgen Klinghardt http://www.eisenfuhr.com

Holbros Ltd., Morvil House, Darent Industrial Park, Erith, UK - Kent DA8 2JZ
Polishing pad

The present invention relates to the structure of a new polishing pad, particularly for use in the finishing of paintwork on vehicles. In particular, it relates to use in polishing away defects left on the paintwork of a vehicle immediately after it has left the spray room during manufacture. This process is known as de-nibbing. As with many manufacturing processes, the requirements for increased productivity require that the de-nibbing step be carried out in as short a time as possible and with minimal risk of causing damage to the paintwork. The de-nibbing tool will of course have applications beyond vehicle manufacture, for example in vehicle repair shops or elsewhere where it is necessary to produce a polish on a painted surface.

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Conventional repolishing pads are polyurethane foam disks manufactured by molding. A well-known pad, manufactured by the Minnesota Manufacturing and Mining Company (3M), and described in detail in U.S. Patents 5,396,737, 5,185,964, and 5,007,128, is 15 cm in diameter and 2.5 cm thick. This particular 3M product is molded to produce rows of curved, gently rounded protruding spheres on the work surface. Each sphere is centered on a node of a rhomboidal lattice so that each protrusion is evenly spaced from each adjacent sphere. In operation, the repolishing pad is attached to a rotary polisher so that its work surface rotates rapidly about the axis of the disk. The work surface is then pressed against the paint surface, often in conjunction with a polishing compound, to polish away imperfections. As explained in the 3M patents, it is very easy to apply the pad to a particular area of the paint for too long a time, which can lead to overheating of the paint, causing serious damage to the paintwork (sometimes referred to as blooming) and consequently large expenditures to repair the damage. The present invention seeks to improve the properties of the previously known repolishing pads.

The present invention features a foam repolishing pad having a work surface, the surface having a pattern of intersecting recesses formed therein, each recess having sides that are perpendicular to the work surface where the sides meet the work surface. In a preferred embodiment of the invention, the work surface is nominally flat.

Preferably, the pattern of intersecting recesses is rectangular, and most preferably square, such that each recess intersects every other recess at a right angle. The pattern may be other than rectangular, but a rectangular pattern produces the best performance in use.

The pad is made by forming a disk with a roughly flat surface that will become the work surface. A recess forming tool consists of a rectangular grid of parallel, stiff wires supported on a support structure. The surface of the pad is then pressed into the grid to a desired depth so that the rectangular pattern of intersecting recesses is formed. The roughly finished surface is then cleanly cut to expose the work surface. The result is recesses that have side walls that meet the flat work surface at right angles. Finally, a conventional reinforcing structure is attached to the back of the repolishing pad, which also provides means for attaching the pad to the polishing tool.

The re-polishing tool according to the invention is thus designed with a flat working surface in which a large number of sharp edges and corners are formed. These edges and corners cooperate to de-nibble the paint much faster than a conventional tool. There is thus no time in which the paint could be overheated and the re-polishing process can be completed more quickly with less effort and with greater reliability than before.

A polishing tool designed in accordance with the invention will now be described by way of example with reference to the accompanying drawings, in which:

Fig. 1 a top view of the work surface,
Fig. 2 a section along AA,
Fig. 3 an enlarged detail C.

The figures show a polishing pad made of polyester foam of the specification "V8 fine" as manufactured by Wilhelm Reisgies GmbH

& Co. KG. The specification for V8 Fine is; Density according to DIN 53420, ISO 845 = 45 kg/m ³ , Compression force deflection DIN 53577, ISO DIS 3386 (40%) = 15 kPa, Yield stress at break DIN 53571, ISO 1798 = 450 kPa, Elongation at break DIN 53571, ISO 1798 = 380%, Compression DIN 53572, ISO 1856 = 11%. This is a non-abrasive foam. Foams with characteristics similar to V8 Fine, particularly polyester foams, have not previously been seen as suitable candidates for use in re-polishing pads or similar applications, they have generally been used for various applications such as sound insulation in vehicles. Polyester foams of this type do not have the high elasticity and, consequently, rapid recovery from deformation as conventional polyurethane foams used in traditional repolishing pads. High elasticity and low density have previously been considered desirable characteristics that allow the pad to conform to the painted surface. Polyester foams are also more expensive than polyurethanes, so there was no obvious reason for a person of ordinary skill in the art to try such foams for the purpose of repolishing.

Special polyurethane foams can also be used in this application such as PPF8 from the source mentioned above. This foam is a polyurethane foam that has been modified for this application by the addition of polyester polyols and other additives to obtain density properties and compression force deflection similar to the V8 fine foam mentioned above. For the reasons mentioned above, the use of such foams in conventional polishing pads is not obvious.

The repolishing pad in the example is a disk 16 cm in diameter and 3 cm thick. The pad has a working surface 1 which is nominally flat. A square cross pattern of recesses 2 is formed in the working surface 1. Parallel recesses are spaced 1 cm apart and each recess is 0.5 cm wide and approximately 0.5 cm deep. The horizontal recesses meet the vertical recesses at right angles and it is

It has been found that this leads to improved properties of the repolishing pad. It is important that the walls 3 of the recesses meet the work surface 1 at a right angle B (90°). The main purpose of the recesses is to create a work surface with a large number of cutting edges.

The pad has a reinforcing structure 4 which is connected to the back and further comprises the means for attaching the polishing pad to a polishing tool.

Claims (9)

1. A foam polishing pad having a working surface ( 1 ), characterized in that the surface has a pattern of intersecting recesses formed therein, each recess having sides which are perpendicular to the working surface where the sides meet the working surface. 2. Polishing pad according to claim 1, characterized in that the working surface is flat. 3. A polishing pad according to claim 1 or claim 2, characterized in that the intersecting pattern of recesses is rectangular. 4. Polishing pad according to one of the preceding claims, characterized in that the cross pattern of recesses is square. 5. Polishing pad according to one of the preceding claims, characterized in that the foam has a density between 40 and 50 kg/m ³ . 6. Polishing pad according to claim 4, characterized in that the foam density is 45 kg/m ³ . 7. Polishing pad according to one of the preceding claims, characterized in that the pad is formed from a foam having a compressive force deflection between 10 kPa and 20 kPa. 8. Polishing pad according to claim 6, characterized in that the compressive force deflection is 15 kPa. 9. A polishing pad according to any preceding claim, wherein the parallel recesses are separated by 1 cm and the recesses are 0.5 cm wide.