Abrading – Frame or mount – Portable abrader
Reexamination Certificate
1998-09-08
2001-02-27
Young, Lee (Department: 3729)
Abrading
Frame or mount
Portable abrader
C451S358000, C451S194000
Reexamination Certificate
active
06193592
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a hand-held material-removing tool in general, and more particularly, to a grinding tool for working sheet material.
In recent years, spot welding has been increasingly used in the field of special body repair, because of the pressure on the automobile producers. Advantages provided by spot welding are in particular that a repair can be carried out according to the standards of the respective automobile producer, and this corresponds exactly to the production process of the vehicle. Particular advantages thereby accrue, that e.g. crash behavior of a vehicle corresponds to the original vehicle, even when the vehicle is extensively provided with new material in elements which are load bearing and those which are not.
Furthermore, the problem arises when the new kinds of high strength steel are used that the conventional protective gas welding process lead to embrittlement because of their high heat content, and can thus limit the strength of the whole vehicle structure.
Furthermore, insuring rust protection after the repair can only be guaranteed by using the spot welding process.
However, a prerequisite for satisfactory spot welding it that all surfaces are metallically bare before the welding process.
2. Description of Relevant Art
The grinding process preceding welding is up to now carried out in the workshops with the tools available there. Angle grinders, belt grinders, wire brushes or similar appliances, which remove the primer and paint in the region of the zone of apposition, are in particular used for this purpose. The process of exposing the sheet metal is however very uneven when working freehand, and therefore it cannot be insured that the existing material thickness is maintained, and the material cannot be prevented from being impermissibly weakened by excessive grinding. Furthermore, sparks which arise, particularly in angle grinding, present a danger to the operator.
Since the work appliances mentioned hereinabove were not originally provided for sheet metal grinding, the ease of handling them can also be expected to give rise to problems when material is to be ground away in small corners or angles. The desired uniform exposing of the sheet metal regions to be welded can then only be attained, if at all, by the use of several tools.
SUMMARY OF THE INVENTION
The invention consequently has as its object to avoid the abovementioned disadvantages. A further object of the invention is to provide a material removing tool which is ergonomic to operate, light and easy to handle, and which insures a constant grinding quality in the whole weld region.
This object is attained in a very surprising manner by a hand-held, material removing tool for processing sheet material, with at least a first abrasive body having on the outer surface thereof a material-remover for processing of sheet material, a drive device for driving the abrasive body, and a second abrasive body driven by the drive device, such that a double-sided simultaneous processing by both abrasive bodies of the sheet material arranged between the abrasive bodies is enabled.
A grinding appliance which can be handled in a simple manner, and which makes possible a simultaneous two-sided sheet metal processing, can be provided by the use of two abrasive wheels which can be driven by the drive device. Not only does a time advantage of at least
50
% as against all known hand-held tools result, but also a metal sheet to be welded can as a rule be finish processed in a single machining process.
In a particularly advantageous manner, the metal sheet to be machined can be securely grasped on both sides by the abrasive wheels, when a respective one of two drive shafts each holding a respective abrasive wheel is arranged to be pivotable toward the other. By this means, the metal sheet to be processed can be gripped as if by tongs by the tool according to the invention, and a substantially equal pressing force is provided on both sides of the metal sheet. In a further advantageous embodiment, one or both of the drive spindles can be constructed as swing axles, thereby decoupling the abrasive wheels from pivoting motions of the operator.
The quality of grinding is greatly improved and kept very constant by means of a control device by which the contact pressure of the drive spindles on the abrasive wheels can be limited or automatically set, independently of the operating pressure of an operator. An always very high quality grinding result can be insured, nearly independently of the actuation by the operator, by the pre-defined contact pressure of the drive spindles, in correspondence with predetermined rpm and/or torque values.
Simple sweeping with the tool according to the invention over the place on the metal sheet which is later to be welded is sufficient to obtain, in a single working process, a precisely defined exposed sheet surface on both sides of a metal sheet to be processed.
Although the invention could in principle also be carried out with abrasive wheels which swing back and forth, the most preferred embodiment includes a drive device with a rotary drive. Furthermore, the abrasive wheels are rotationally symmetrical abrasive wheels, such as are described in the German Utility Model of MV Marketing und Vertriebs-GmbH & Co. KG Wieländer+Schill with the title “Tool for Material-Removing Processing,” with the same filing date as the priority application for the present invention which Utility Model is incorporated herein by reference. This abrasive wheel is substantially characterized by an outer jacket which is automatically aligned parallel to the surface to be processed. With an abrasive wheel of this kind, the tool according to the invention can have a pendular axle and a rigid axle for driving the abrasive wheels. A reliable grinding result is always achieved over the whole width of the abrasive wheel, even when a tilting of the tool occurs.
If the hand-held material-removing grinding tool has at least one axial stop that forms a guide device for the abrasive wheel relative to the edge of the metal sheet to be processed, preferably together with a suitable choice of the width of the abrasive wheel, precisely defined regions of the sheet surfaces to be exposed can thereby be predetermined in a very simple manner. The operator only has to pull the tool according to the invention along, with the axial stop on the metal sheet, and thereby achieves exposed sheet regions which very exactly correspond to the weld points predetermined by the respective automobile producer.
If the drive shaft of the abrasive wheel, or the abrasive wheel itself, is removably attached to the tool, a rapid change of used abrasive wheels is thereby made possible. If, however, one of the two abrasive wheels is removed together with its associated drive shaft, the tool according to the invention can be used for single-sided processing, such as at places of a vehicle body which are accessible from only one side, or with difficulty. A universal tool is thereby provided which can process nearly all seams on body parts, and avoids the recourse to additional tools.
A further lightening of the work of the operator results from an actuating element which is arranged laterally on the tool according to the invention and which can be operated with one hand and makes all the operating processes possible with one handle.
In a particularly advantageous manner, the actuating element can be secured against switching on when in the switched-off basic position, the abrasive wheels can be pivoted toward each other in the position with the safety device released, and the drive motor can be switched on before or during the pivoting of the abrasive wheels. In a preferred manner, the release of the safety device can take place by a simple longitudinal displacement of the actuating element, and the pivoting of the abrasive wheels can be effected by pressing this element in.
In an embodiment which is suitable for use in a professional workshop, the drive motor is a pneumatic motor
MV Marketing und Vertribes-GmbH & Co. KG Wielander + Schill
Smith Sean
Young Lee
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