Belt surfacing tool

An endless-belt surfacing tool is disclosed, consisting of a perforated metal sheet with burrs formed by the perforations, the sheet being welded to form a belt, where the weld is made on the same side of the sheet as the burrs formed by the perforations, the height of the weld being less than that of the burrs, and where the ends of the belt are welded at an angle to the length of the belt.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention is in the field of devices for finishing surfaces; more 
specifically, this invention is in the field of abrading means for belt 
sanders and the like. 
2. Description of the Prior Art 
In my U.S. Pat. No. 4,028,781, I disclose and claim a metal sheet having 
perforations therein, the sheet being useful in place of sandpaper for 
reciprocal and orbital sanding machines. While such a sheet has utility 
and a much greater durability and life than conventional sandpaper or 
emery cloth, it is by its very nature restricted to the general line of 
machines which provide a reciprocating motion, and obviously cannot be 
used on a belt sander. 
There have been other attempts to provide abrasive means useful with a 
rotary application. Bertrand, in U.S. Pat. No. 1,789,298, shows an 
abrading strip helically wound on a drum, the ends of the strip being 
secured to the drum at the ends thereof in such a fashion that the surface 
of the drum is effectively covered with the strip. By this arrangement, 
the drum can be used as an abrading device operating in the rotational 
mode as opposed to the reciprocal. Bertrand, however, has no provision for 
the application of any part of the abrading surface in the planar 
conformation, the strip conforming to the curved drum surface. 
Caston, in U.S. Pat. No. 2,518,448, makes provision for both a rotary 
application and the possibility of applying a planar portion of the device 
to the work. Caston discloses an endless belt made of flexible steel, 
being carried between two drums, whereby either a planar or a curvilinear 
surface may be presented to the work. There is no disclosure in the '448 
patent, however, of the nature of the joinder of the ends of the original 
metal band to form the endless belt. 
In using endless metal belts, one problem which has been observed is that 
the weld area causes the belt surface to rise in relation to the drum as 
that area of the belt passes over the drum. In the planar portion of the 
belt, the problem is not so acute, but a different problem arises when the 
weld line is perpendicular to the direction of travel of the belt, that 
problem being that there is a gap in the abrading surface. 
SUMMARY OF THE INVENTION 
The present invention is an endless-belt abrading tool consisting of a 
metal sheet from about 0.2 to about 5 millimeters (mm) thick, perforated 
with punched holes, the burrs from the punching forming an abrasive 
surface. The total area of the perforations is not greater than one-half 
of the total area of the original sheet surface. The ends of the sheet are 
joined by a butt weld where the welding operation is performed on the burr 
side of the sheet, the weld line being at an angle to the direction of 
travel of the finished belt, the height of the weld being less than the 
height of the burrs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The preferred embodiment of the present invention consists of a metal belt 
of a thickness from about 2 to about 5 mm. The sheet from which the belt 
is made is perforated with punched holes whereby the burrs from the 
punching operation form an abrasive surface. The total area of the punched 
holes or perforations must be no greater than the total area of the 
remaining non-perforated metal, preferably no greater than about one-half 
the total area of non-perforated metal, and the distance between the edge 
of any given perforation and any other edges such as the nearest 
perforations or the edge of the metal sheet is no less than about 0.75 
times the smallest lateral dimension, e.g., diameter of the smaller of the 
two perforations, nor more than about four times the minimum lateral 
dimension of the larger of the two perforations. The minimum lateral 
dimension of any perforation is about 0.75 mm, and the maximum lateral 
dimension of any perforation is about 4 mm. Preferably, these lateral 
dimensions range from about 1.5 to about 2.5 mm, and the length of each of 
the burrs surrounding said perforations is in the range of from about 0.75 
to about 3 mm, more preferably from about 1.5 to about 2.5 mm. Preferably, 
all the perforations are substantially the same size, and the areas of the 
perforations range from about 0.5 to about 12 square mm. 
FIG. 1 shows the belt of the present invention, partially cut away to show 
the features of the invention. Belt 11 is formed of a material capable of 
being punched or otherwise worked to produce holes 12, where the edges of 
the holes then become burrs 13 which collectively make an abrasive 
surface. Metal is a convenient material, with steel being preferred, and 
stainless steel being most preferred. Holes 12 are punched in such a 
manner as to provide burrs 13 oriented all in one direction on surface 14 
of belt 11. Holes 12 are shown as circular, but can as well be elliptical, 
polygonal or irregular. 
The manner of piercing or punching belt 11 is well known to those skilled 
in the art, and forms no part of this invention as such. Such operations 
include, e.g., die punching, explosive methods, and electric-arc piercing. 
The ends 17 and 18 of belt 11 are joined at weld line 15 to produce an 
endless belt. Those skilled in the art will realize that the joinder must 
be made with ends 17 and 18 juxtaposed to permit belt 11 to run true on a 
plurality of drums or other rotational means. 
FIG. 2 shows belt 11 in a side view, the belt having been formed into an 
endless belt. Weld 16, shown in more detail in FIG. 3, is made on the side 
of surface 14 of the belt, the same side as the protrusion of burrs 13. 
FIG. 3 is an enlargement of the view at reference character 16, showing the 
weld 16 in greater detail. The belt is welded at line 15 by any means 
known to those skilled in the art, such as, e.g., automatic arc or 
resistance welding, which means form no part of this invention. However, 
it is important to the proper operation of the belt that the weld 16 
produce no impediment to the abrading function of the belt for a 
substantial portion of the life of the belt. Therefore, the weld 16 must 
have no material projecting from surface 14 more than the length of the 
shortest burr, or about 0.3 mm, and preferably not more than about half 
that amount. 
To prevent irregular motion of the belt around a drive or idler drum, such 
as found in a drum sander or the like, no weld metal may be deposited on 
the interior surface of the belt, where such additional material would 
produce a hump on the belt surface. That is to say, the interior surface 
of the belt must be without substantial irregularity. 
Referring again to FIG. 1, weld line 15 is shown as being at an angle to 
the length of the belt. If line 15 is perpendicular to the length of belt 
11, too much stress is imparted to weld 16, causing unacceptably early 
fatigue failure of the weld, or of the material close to it, due to 
excessive flexing. Further, because of the physical necessity of access to 
the weld line of the equipment used to perform the welding function, there 
is necessarily a gap in the burrs in that area. By joining ends 17 and 18 
at an angle to the length of the belt, stress on the weld line is reduced, 
and the effective region of decreased burrs is spread over a larger area 
when the belt is in use. 
Those skilled in the art will realize that the belt 11 herein described can 
be formed initially in a belt configuration without any seam or weld, by 
extruding, drawing or other convenient operation to produce the belt, 
which is then made of the lateral dimension desired by appropriate means 
such as cutting. The formation of the burrs 13 is then accomplished by 
means such as described herein. 
The angle formed by line 15 and the long line of the belt shown in FIG. 1 
is 70.degree., and is a preferred angle for joinder. However, angles of 
from about 30.degree. to about 80.degree. are useful, and within the 
spirit and scope of this invention. 
In the embodiment shown in FIG. 1, circular perforations of about 2 mm in 
diameter have been punched in a substantially rectangular pattern spaced 
on about 4.5-mm centers, with no perforations closer than about 2.5 mm to 
any edge of the belt, either before or after weld 16 is made. In this 
fashion, the holes made in the belt comprise about 30 percent of the total 
belt surface. The total area of the holes in belt 11 preferably comprise 
less than about half of the total area of the belt, to resist distortion 
and stretching. 
If 4-mm holes are punched in the belt rows having axes at about 60 to the 
length of the belt, with about 6 mm between centers, the area of the holes 
comprises about 45 percent of the total area. As described hereinabove, no 
hole should have its center closer than about 2.5 mm to the edge of the 
belt, in order to avoid tearing the belt. The arrangement of holes in rows 
at 60.degree. to the length of the belt is preferred, providing the 
greatest amount of abrading surface consistent with belt integrity. 
The thickness of the belt is necessarily dependent upon the material from 
which it is made. If the belt is formed from stainless steel, the 
practical minimum is about 0.2 mm. If it is greater than about 0.5 mm, the 
material appears to be too stiff for practical utility as an abrading 
belt. 
Modifications, changes and improvements to the preferred forms of the 
invention herein disclosed, described and illustrated may occur to those 
skilled in the art who come to understand the principles and precepts 
thereof. Accordingly, the scope of the patent to be issued hereon should 
not be limited to the particular embodiments of the invention set forth 
herein, but rather should be limited by the advance by which the invention 
has promoted the art.