US2409490A - Tuft anchoring means for brushes - Google Patents

Description

Oct. 15, 1946. c. Jo BsT TUFT ANCHORING MEANS FOR BRUSHES Filed May 11, 1944 INVENTOR. CONRAD JOBST ATTORNEYS Patented Oct. 15, 1946 UNIT-El) STATES; PATENT OFFICE TUFT ANCHORING MEANS FOR BRUSHES Conradlobst, Toledo, Ohio, a ssig nor to The Toe ledo Automatic Brush Machine Company, To-

ledo, Ohio, a corporation of Ohio Application May 11, 1944, Serial No. 535,166

1 Claim.

The invention relates to means for anchoring tufts in brush backs and has more particular application to brush backs formed of molded plastic material. In the present state of the brush art, molded synthetic plastics have been extensively used for the forming of backs and handles of brushes. The tufts are set in such backs in much the same way as in the earlier type of backs formed of other materials. Also it has been the practice to secure the tufts by staples or other metallic anchoring members.

I have discovered that tufts may be secured within the bores of a plastic brush back by means of an anchor formed of certain types of plastic materials and that these anchors may be applied by a tuft setting mechanism such as described in my previous Patent No. 2,084,345 of June 22, 1937. The essential features of the mechanism shown and described in this patent are, first, that a strip or ribbon is intermittently advanced to shearing means which severs an anchor length therefrom, after which the severed portion is moved laterally into the path of a driver by which it is driven through the tuft setting nozzle into a registering bore of the brush back carrying the tuft therewith. While the metallic anchor described in my patent is of slightly greater length than the diameter of the bore so that it forms grooves on diametrically opposite sides of the latter, I have found that the plastic anchor of the present invention need be no larger than the hole.

When the plastic anchor is driven into the hole in the brush back, the plastic material of the anchor softens by means of the heat generated during the impact with the brush back and it is deformed into a shape which interlocks with the brush back and forms a bond. therewith, thus firmly holding the bristles in the bore.

The invention will be more fully appreciated by reference to the accompanying drawing, in which Figure 1 is a cross section through a brush back showing the bristle tuft and plastic anchor as it enters the bore;

Figure 2 is a similar view showing the tuft and anchor after it is inserted in the bore;

Figure 3 is a transverse section on line.3--3 of Figure 2;

Figure 4 is a section on line l-d of Figure 2;

Figure 5 is a side view of an anchor after insertion showing on an exaggerated scale the deformation of the material to conform to the bristles of the tuft;

Figure 6 is a section on the line 6-6 of Figure 5.

I0 is a brush back having a series of tuft-receiving bores ll formed therein in the usual manner. A tuft of bristles l2 doubled over an anchor I3 is inserted in the bore by means of the driver or inserter M of a suitable tuft-setting mechanism such as described in my Patent No. 2,084,345.

Theanchor is preferably a rectangular slug of a length substantially the same as the diameter of the bore and of a lesser width. It is severed from a strip of relatively thin material in the same manner as set forth in my prior patent.

However, instead of using a corrosion-resistant metal alloy as has been done in the past, I use a plastic material of a type that will soften or even melt under the influence of the heat generated by the impact when the tuft is inserted in the brush back.

Thus, as shown in Figure 2, the force of the impact causes the ends N5 of the anchor to be deformed and to penetrate the side walls of the bore as indicated at I6, thereby forming a mechanical interlock. Moreover, the softening or melting of the ends of the anchor results in the formation of a bond between the anchor and the brush back, which assists in retaining the anchor in its set position and firmly securing the bristle tuft.

While the anchor is in its softened condition during the insertion, the individual bristles of the tuft become embedded in the leading edge ll of the anchor and to a certain extent in the side faces 18 of the anchor, thereby forming grooves ill in the edge and grooves 20 in the side faces. This is diagrammatically illustrated in Figure 5 where the grooves are shown on an exaggerated scale.

In the broader phases of my invention, the anchor may be made of any non-metallic plastic material which is capable of being so influenced by the impact of the insertion as to form a mechanical interlock or bond with the brush back to securely hold the tuft in position. More specifically, I have found that it is desirable to use a resin which may be identified as a viny1 chloride-vinyl acetate copolymer containing -95% vinyl chloride and having an average molecular weight of 10,000 to 25,000 as determined by the Staudinger method. As an example of resins'of this type, reference may be made to U. S. Patent No. 1,935,577 and to an article by Curme 8; Douglas, published in the October 1936 issue of Industrial and Engineering Chemistry.

The material of the brush back may be any of the usual types of plastics commonly used for this purpose such as Celluloid, cellulose acetate, butyrate, etc.

through the transparent back. A very important advantage is the interlock which is produced by the lateral expansion of the anchor during the setting operation. A further advantage is that the material is not subject to corrosion as is the case with certain metals from which anchors have been formed. An important advantage is that the plastic anchor forms abufier between the driver l4 and the bristle tuft, thus preventing the injury of the bristles during the setting of the tuft in the brush back.

While I have disclosed a preferred embodiment of the invention, it is to be understood that it is not limited to the specific construction herein defined, but covers various modifications coming within the purview of the appended claim.

What I claim as my invention is:

In combination with a brush back of a polymerized synthetic plastic material and having a bore therein and a bristle tuft within said bore, of an anchor formed of a copolymer of vinyl chloride and vinyl acetate, said anchor having the ends thereof laterally expanded to be embedded in the walls of said bore and bonded to

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