US1974795A - Brush - Google Patents

Description

` sept. 25, 1934. c; CAHEN ET AL 1,974,795

BRUSH Original Filed Dec. 16. 1931 Patented Sept. 25, 1934 UNITED STATES PATENT OFFICE Renewed May 7, 1934.

3 Claims.

The present invention relates to the manufacture of brushes both large and small, and to the resulting manufactured products. It particularly concerns an arrangement which permits maintaining the hairs or bristles firmly assembled in a bunch or tuft.

In the known arrangements, -the hairs are maintained by a sheet metal piece or ferrule, by which they are surrounded over a considerable length. The length of the hairs thus surrounded cannot be used, forming a drawback, since the commercial value or price of the brushes depends, as is well known, upon the effective length of the hairs or bristles. The present invention permits firmly assembling the hairs by contact over only a small part of their length, and thus the effective length of the hairs is greater than when the known methods of manufacture are used.

I-Iitherto, the assembly was made by winding around the set of hairs a sheet metal band which was tightly pressed against the hairs, and as the band had a certain width, the hairs were retained by friction. On the contrary, according to our invention, the hairs are mounted in a ring in such manner that the butt ends of the hairs are all contained in the said ring or are near the same. It is a known fact that a hair or bristle has a tapered shape, thus having a top or small end and a bottom or butt end. Our new ring has but a small height, and thus it would be insufficient to retain the hairs by friction, and for this reason, rods of large diameter are driven into the ring, these being in the same plane and perpendicular to the axis of the bunch of bristles. The diameter of the rods is such that when they are inserted, they will reduce by at least 15 per cent the surface of the cross section of the bunch in the interior of the ring; and preferably, the section is reduced by 25 per cent. The space between any two rods and the inner wall of the ring thus forms a recess in which the bristles are firmly pressed and from which they cannot escape, owing to their tapered form.

It has already been proposed to: drive small nails into a bunch of bristles, and such nails serve only to secure the bunch of bristles to the wood handle. The diameter of these nails and their number in a given plane are, however, insufficient to reduce the surface of the bristles in this plane by 15 per cent; thus the bristles are not maintained in place, and in order to hold them it is necessary to employ a ring or ferrule of considerable height in order to hold the bristles by friction, or else a tapered ferrule must be used,

In Germany December whose smallest cross section is distant from the "r plane vof the nails. In another arrangement, nails of small diameter have been used in order to give the ferrule a shape different from that of a ring, for instance in the flat brushes; and herein the nails extend clear through the ferrule and are riveted at their ends in such manner as to maintain the proper spacing between the opposite walls of the ferrule. This arrangement is not as satisfactory as the present, as in the known 55 construction the diameter and number of the nails are insufficient to produce the desired effect, while on the other hand the sheet metal of the ferrule is very thin, and is not sufficiently rigid to withstand the high pressures produced in the 7.0 present arrangement.

The ring preferably has a circular shape, as this will prevent all distortions due to high pressure.

It is advantageous to give the ring the form of a truncated cone whose small base is quite close g5 to the plane of the rods, and thus the ring will add its effect to that of the rods.

In the accompanying drawing:

Figure 1 is a section on the axis of a bunch of bristles, according to the invention. Figure 2 is a horizontal section on the line II-II of Figure 1.

For the manufacture of the set of bristles shown in Figures 1 and 2, the bristles 1 are first assembled in such manner that all the small ends are at the top, the butt ends being at the bottom at 3. The bottom part of the bunch is then inserted into a ring 4 having the shape of a truncated cone. The ring consists of copper, and has a diameter of 34 mm. and a thickness of 1 mm.; 90 so that it will be strong enough to resist all distortion. Holes are pierced in the ring 4 near its narrowest part 6; the wedging rods 5 are inserted through the said holes and have the radial position, all the rods being situated in the same plane. The rods have a circular cross section and are 2 mm. in diameter.

In this manner the bristles are distributed among the spaces which are formed in each case by a part of the wall of the ring 4 and of any 100 two adjacent rods 5; in each space, the cross secf tion available for the bristles increases when approaching the butt ends of the bristles, and thus the latter are wedged into place.

On the other hand, they are rmly held in .105 place, as the cross section available for the bristles before inserting the rods, that is, the surface within the ring and adjacentv the rods, is 910 sq. mm.; the total surface covered by the rods in the common plane passing through their axes is ,110

192 sq. mm.; or 21 per cent of the surface of the rod, and thus after inserting the rods, the surface left for the bristles is only '718 sq. mm. Hence the reduction of the cross section is 21 per cent. To this must be added the tightening action due to the narrowest part 6 of the ring. It will be noted that a very small part of the length of the bristles is made ineffective by the ring 4; this part is equal to the height of the ring, or about '7 sq. mm.

Obviously, the ring 4 may consist of a sheet metal strip or of a Wire Winding, without departing from the principle of the invention or the method of manufacture.

What We claim is:

1. A bunch of bristles comprising a tapering ring enclosing the butt ends of the bristles, and nails of large diameter extending through the ring and part Way across the bristles, the said nails extending perpendicularly to the major axis of the bunch of bristles and being all situated in substantially the same plane, perpendicular to the said axis.

2. A bunch of bristles according to claim 1 in which the plane of the said nails is closely adjacent to the small base of the tapering ring.

3. A bunch of bristles following claim 1, in which the rods have a diameter such that the total surface occupied by the rods in the plane common to their axes, represents more than a sixth of the total surface of the circular area of the ring in the said plane.

GEORGES CAI-IEN. PAUL CHEVALIER.

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