WO1996016586A1

WO1996016586A1 - Scraping tool

Info

Publication number: WO1996016586A1
Application number: PCT/SE1995/001387
Authority: WO
Inventors: Karl-Erik Forsberg; Erik Sundström
Original assignee: Sandvik Ab
Priority date: 1994-11-30
Filing date: 1995-11-22
Publication date: 1996-06-06
Also published as: SE502445C2; SE9404143D0; SE9404143L

Abstract

Scraper and blade for removal of paint or rust, where the blade has one center hole (23) and a contour comprising portions of different curvature, and with several points (24) along the contour having a maximum distance to the center of the hole which is nowhere exceeded, and the scraper having a contact surface with a hole for a screw and an arcuate support step (15) the center of curvature of which coincides with the center of the hole for the screw.

Description

Scraping tool Background

Scraping tools have long been known for removal of rust or old paint from surfaces, with exchangeable blades, usually with straight edges, such as shown in the patent US 4,768,254, US 4,890,351 and US 5,056,226. It is also known to make scrapers with circular edges or with two adjoining edges at an angle for scraping concave mouldings and corners as described in DE G90 05799.6. Scrapers with cutting blades of thin steel which can be ground to any desired shape and located in a number of distinct positions by means of multiple holes and a locating peg are also known from US 5,440,811.

However, scrapers and blades suited for a greater variety of surfaces with different curvature such as occur on decorative mouldings, reliefs or inscriptions, have been missing. Nor has there been available blades suited for scraping flat surfaces merging into curved surfaces. The present invention concerns a type of blade useable for convex or concave or flat surfaces, and a scraper adapted to hold such blades. One desirable feature of this scraper is that the blades can be set at any angle, not only a number of distinct positions.

Description

The invention is described with reference to the figures, where figure 1 shows a scraper, and figures 2 - 4 show different types of scraper blades according to the invention.

A scraper as shown in figure 1 has a handle (11) , a neck (12) extending from the handle and blade holder comprising a contact surface (13) , a screw (14) and an arcuate support step (15) . The contact surface shall form a non-zero angle with the neck (12) , preferably from 40 to 80 degrees. The support step (15) is rising from the contact surface and comprises at least 60 degrees of a circle, preferably from 90 to 150 degrees, and is located between the contact surface and the neck. The screw (14) is inserted in a threaded hole in the contact surface, at the center of curvature of the support step, or close to this point. It is preferably provided with a conical head, pressing the blade against both the contact surface and the support step.

A scraper blade according to the invention has two flat sides (21,22) and one central through hole (23) . The blade is made from a hard wear-resistant material, preferably tungsten carbide or hardened steel . Along the contour of th blade runs an edge surface, which depending on the field of application can be at right angles to the flat sides, or form an acute angle to one side, or be hourglass shaped to form acute angles to both sides. A sharp edge is formed where the edge surface meets one or both sides.

The contour of the blade should be such that the distance to the center of the hole (23) from several points (24) of the contour should be the same, and nowhere larger, and thi distance should be equal to the radius of curvature of the support step (15) . A circle with that radius can then be circumscribed around the contour. The number of points (24) with this maximum radius and their distribution along the preiphery should be such that in any intended operational position of the blade there is at least one point touching the support step. If the whole contour of the blade is to b used in arbitrary positions, this means that such points (24) should not be missing from any part of the contour longer than the support step.

Figure 2 shows a blade to be used for scraping the surface of metal wires, rods or tubes clean, the contour of which comprises convex arcuate portions (25) with the same radius as the circumscribed circle interspersed with concave portions (26) with smaller radius.

Figure 3 shows a blade where the contour comprises some straight portions (27) merging into convex portions (28) with lesser radius than the circumscribed circle, some concave portions (29) with much smaller radius and a sharp convex corner (30) . The points (24) with equal maximum distance to the center are located on convex portions of the contour. Such a blade can be used to scrape flat surfaces merging into concave surfaces, where it is important to avoid scratching the concave surface. The concave portions can be used for rounding of external corners or for deburring of sheet or panel materials. The sharp convex corner, the angle of which should be slightly less than 90 degrees can be used to scrape internal corners.

Figure 4 shows a blade, the contour of which comprises a concave portion (31) with large radius, a convex portion (32) and a portion with undulating shape (33) . The concave portion (31) is to be used for cylindrical items such as pillars or handrails and has the advantage of being self- centering without tendency to slip off to the side, and without risk of scratching the item. The portion with undulating shape (33) is to be used for a first rough scraping of very thick layers of paint or rust, on flat or curved surfaces.

The invention is not restricted to the blade shapes shown in the figures 2 - 4, and the blades can be shaped for various purposes with different combinations of convex, straight or concave edges, as long as there are several points (24) of the contour touching the circumscribed circle. The support step (15) of the scraper need not be continuous, but may have one or more short interruptions (34) to make it possible to locate triangular blades stiffly in defined positions. The handle can be made to fit one or two hands, as is known in prior art.

Claims

1. Blade for a scraper for removing of paint or rust, havin two sides (21,22), one central hole (23) and a contour, characterized by the contour comprising portions with different radius of curvature, and by several points (24) along the contour having a maximum distance to the center o the hole which is not exceeded at any point.

2. Blade according to claim 1, characterized by the contour comprising convex (25) as well as concave (26) portions.

3. Blade according to claim 1, characterized by the contour comprizing convex (28) as well as straight (27) portions.

4. Blade according to claim 1, characterized by the contour comprising sharp convex or concave corners.

5. Blade according to claim 1, characterized by having a heart-shaped contour with two convex portions (28) , two straight portions (27) , one convex corner (30) and one concave corner (29) .

6. Blade according to any of claims 1 to 5, characterized b being made from tungsten carbide.

7. Blade according to any of claims 1 to 5, characterized b being made from hardened steel.

8. Scraper for removal of paint or rust, comprising a handl (11) , a neck (12) , a replaceable blade with two parallel sides (21,22) and one hole (23), characterized by having a flat contact surface with a hole for a screw and an arcuate support step (15) the center of curvature of which coincide with the center of the hole for tha screw.