Stem brush and method for making same
US 3124823 A
Abstract available in
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Description (OCR text may contain errors)
March 17, 1964 v. K. CHARVAT 3,124,823
STEM BRUSH AND METHOD FOR MAKING SAME Filed April 19, 1961 FIG I WWII/WMQMl/MI FIG2 F|G3 INVENTOR.
VERNON K. CHARVAT 0111mm, a/Donndly ATTORNEYS United States Patent 3,124,823 STEM BRUSH AND METHOD FOR MAKING SAME Vernon K. Charvat, Bay Village, Ohio, assignor to The Osborn Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Filed Apr. 19, 1961, Ser. No. 104,152 21 Claims. (Cl. -206) This invention relates as indicated to a brushing tool, and more particularly to a brush having a generally helically arranged layer of brush material secured between two twisted wire stem members. Brushes of this type are frequently employed for the cleaning of boiler tubes and the like and are often known as tube brushes.
In the usual twisted stem brush utilizing wire brush bristle material clamped between the twisted stem members, the harsh treatment to which the brush is subjected generally causes premature failure of the brush long be fore such brush is actually worn out. Due to the localized region in which the wire bristles are gripped, such bristles are subjected to concentrations of stress in use which result in long fracture of the bristles and consequent deterioration and destruction of the brush while the bristle ends have been subjected to relatively little wear. Vibration of the fill wires also causes migration of the latter with consequent occurrence of local voids resulting in uneven brushing action and eventual loosening and escape of some of the bristles. In Peterson Patent 2,895,155, there is disclosed an improved wire stern brush construction which represents a substantial improvement over the prior art, and the present invention may be considered a further improvement on such Peterson disclosure. More particularly, I bond the layer of bristle material to the supporting stem members in a novel manner to prevent shifting of the latter and also flexibly resiliently to reinforce such bristles in a gradual manner so that the supporting effect is gradually reduced outwardly toward the working ends of the bristles; in consequence, there is no localized region of attachment of the bristles where working stresses may be concentrated and the bristles are not subject to abrupt bending in any such local region.
It is accordingly an object of this invention to provide a wire stem brush in which the bristles are firmly secured and supported in a manner to avoid localized flexing of the same.
Another object is to provide such brush, and particularly twisted stem brush in which the bristles may be arranged and secured in a single row.
A. further object is to provide such brush in which the stern wires are adhered together in a manner to prevent their spreading apart in use.
Still another object is to provide such brush in which such stem wires are secured together in a manner to prevent such wires from shifting laterally relative to one another.
A still further object is to provide such brush having much increased working life and improved brushing efficiency.
Other objects of the invention will appear as the description proceeds.
To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.
In said annexed drawing:
FIG. 1 is a side elevational view of a twisted stern brush in accordance with this invention but showing different amounts of supporting material for the brush bristles in longitudinally spaced regions;
FIG. 2 is a -fragmentary transverse section on an enlarged scale through such twisted stem brush taken on the line 22 on FIG. 1; and
FIG. 3 is a similar transverse section of a modification utilizing half-round stem wires and a thicker layer of brush bristle material.
Referring now more particularly to such drawing, the embodiment of the invention shown in FIG. 1 may comprise two stem wires 1 and 2 having a layer of bristles 3 interposed therebetween, such stem wires being twisted tightly together as shown to grip the brush material and dispose the latter in a generally helical layer. The stem wires will ordinarily be steel wire although other materials such as brass, stainless steel and aluminum wire, for example, may be utilized as desired. Likewise, the brush material employed will ordinarily be steel wire either straight or crimped, but may be other metallic wire, or plastic filaments such as nylon.
For purposes of illustration, several different forms of the invention have been shown in the single FIG. 1 of the drawing although it will be appreciated that ordinarily.
the entire length of any individual brush will be uniform in accordance with one or another of the embodiments described below. Thus, at the extreme left end of FIG. 1 as viewed in the drawing, the brush bristle material 3 is shown gripped between the twisted stern members 1 and 2 in conventional manner without provision of the special bristle supporting material of this invention. As shown at 4, however, such stem wires may be bonded together by an adhesive elastomeric material which also extends -a short distance outwardly along the bristles to reinforce the latter. In the regions successively indicated by the numerals 5, 6, '7 and 8, the stem wires are similarly bonded together and the supporting material extends progressively greater distances radially outwardly of the layer of brush material, filling the space between the latter, and in the region denoted by the numeral 8, the outer working bristle ends protrude only a relatively short distance beyond such supporting material.
.As better shown in FIG. 2 of the drawing, such supporting material 9, which may, for example, preferably be an elastomeric material such as polyurethane, is shown bonding the stem wires 1 and 2 together and also extending a relatively short distance approximately equal to the diameter of an individual stem wire outwardly in each direction along the bristles 3 which are gripped between such wires. By thus bonding the stem wires together, the latter are substantially prevented from springing Iapart as they may otherwise tend to do following the twisting operation, the wires being mechanically held tightly twisted until the strongly adherent polyurethane resin has set. Such resin likewise serves to prevent spreading apart of the stem wires when the tool is placed in use and thereby ensures that the layer of brush bristles remains firmly gripped and will not be loosened and shed in use. Therehas in the past also frequently been a tendency for the twisted stem wires to shift laterally of one another so that they are no longer directly opposed to one another in the most effective position to grip the brush bristle layer, and this undesired action is similarly prevented by the bonding medium 9. Furthermore, such bonding medium extends an appreciable distance longitudinally outwardly along the brush bristles to afford progressively diminishing support for the latter while at the same time bonding such bristles to the stem wires themselves. In consequence, the bristles are resiliently supported adjacent the region where they are gripped by the stem wires in a manner preventing longitudinal concentrations of stress in the bristles when the brush is placed in use, regardless of whether such use involves axial reciprocation of the brush or rotation about the axis of the central support, or a combination of such actions. In effect, due to the gradually diminishing thickness of the bristle supporting medium 9 outwardly along the bristles, a gradually uniformly diminishing degree of flexure is permitted to such bristles radially inwardly toward the central support and there is no localized point or region where the bristles tend to be sharply flexed when the brush is placed in use.
A generally similar situation prevails in the regions indicated at 6, 7 and 8 on FIG. 1 except that the elastomeric bonding material, which bonds strongly both to the stem wires and the brush material, extends outwardly a substantially greater distance with the outer end portions of the bristles projecting a shorter distance therebeyond and with the elastomeric bonding material completely enclosing and protecting the central twisted stem wire members 1 and 2. The brush bristles accordingly are capable of a stronger or harsher brushing action but are still supported in the general manner described above in that such supporting material extends outwardly along each layer of bristles in a manner to support the latter to a gradually diminishing extent so that there is no sudden or abrupt release of the bristles thereby which would tend to promote sharply localized bending of the bristles in use.
Now referring more specifically in FIG. 3, the embodiment of the invention there illustrated is generally similar to that shown in FIG. 2 but half round stem wires 16 and D1 are employed to grip the layer of brush bristle material 12 between their opposed fiat faces, thereby affording a more secure clamping action on the latter. While the layer of brush bristle material 12 is shown as being several bristles in thickness, it will be understood that this form of construction may be utilized when clamping but a single row of bristles therebetween (as in FIG. 2), and that, equally, the FIG. 2 embodiment may likewise be utilized when clamping a layer of bristles of greater thickness than illustrated. The elastomeric material 13 serves to bond the twisted stem wires 10 and 11 together and also to bond the bristles 12 together and to such stem wires in the same general manner as in the FIG. 2 embodiment.
As will be noted from an inspection of FIGS. 2 and 3, the elastomeric material may desirably assume a meniscus shape in the region between each stem wire and the layer of brush material to achieve the gradually diminishing flexible support for such brush material which it is an object of this invention to obtain. In some cases, and particularly when the elastomeric bristle supporting material extends a substantial distance radially outwardly of the tool as shown at 6, 7 and 8 in FIG. 1, it is desirable that such elastomeric supporting material be of cellular structure having a multitude of small cells therein, the term cellular being employed to include both structures where the cells intercommunicate with one another and where such cells are entirely separated from one another by intervening webs. Foamed polyurethane has been found satisfactory inasmuch as it has a high heat distortion point, good flexibility, tensile and compressive strength, good adhesive properties, and may be applied in liquid form without the necessity of employing molds to produce the desired meniscus mentioned above. Inasmuch as the outer working portions of the bristles protrude appreciably beyond the body of the supporting material, unnecessary rubbing of such supporting material against the work being brushed is avoided which would otherwise tend to generate undesirable heat.
In a sense, it appears that the elastomeric supporting material as shown in FIG. 2, for example, acts like wedges interposed between the layer of brush fill material and the stem wires 1 and 2, with the additional factor that these elastomeric wedges are adhered both to the stem wires and the fill material and accordingly act in tension as well as in compression. As long as the stem wires are not permitted to shift relative to one another, the brushing load will not be transmitted to such wires in any multiplying manner as does occur when such stem wires move apart and a moment arm is provided. Once the stem wires move somewhat apart, the forces tending to separate them in use become very much larger.
While polyurethane is ordinarily much preferred as the bonding and supporting medium, other elastomeric materials such as neoprene (polychloroprene), polyurethane rubber, and vinyl resins may be utilized in a similar manner. Liquid or semi-liquid resins which will form the desired meniscus will usually be selected, and such liquid resins which are capable of rapid gelling are desirable. The stem wires and bristle wires may be treated with an appropriate primer such as an epoxy resin to enhance the bonding effect of the resiliently deformable elastomeric material. The liquid resin is placed on the brush and the latter rotated slowly (e.g. 25-35 r.p.m.) about its axis while the resin gells. The operation is facilitated if such resin is one having a fairly high surface tension.
In a typical preferred example, the bristles may be carbon steel wire having a diameter of .0O2.0l0 inch and a Knoop hardness in excess of 600, the elastomeric material being polyurethane. The stem wires need not necessarily be twisted together but may instead extend closely parallel to one another as shown in Peterson Patent 2,465,396, for example, with the brush material forming a straight flat layer. Flat faced stern wires as shown in FIG. 3 are especially suitable for use in this manner. As taught herein, relatively small amounts of resiliently deformable elastomeric material employed in a strategic location, of proper shape, and bonded to the bristles, serve greatly to extend the region where the principal bristle bending takes place and hence increases the serviceable life of the brushing tool.
In another example, a brushing tool in accordance with this invention was produced utilizing .8 grams of fill Wire, and a twisted wire stem 7 inches in length, the brush being /1. inch in diameter and having a brush face 1 /2 inches long. The brush was heated to about 200 F. before applying a heated polyurethane rubber composition and then rotated at 25-35 r.p.m. until such composition gelled. After complete gellation, the brush was baked in an oven at 212 F. for two hours.
Other modes of applying the principle of the invention may be employed, change being made as regards the de tails described, provided the features stated in any of the following claims or the equivalent of such be employed.
I therefore particularly point out and distinctly claim as my invention:
1. A twisted wire stem brush comprising two stem wires twisted together with brush material clamped therebetween, and elastomeric material strongly adhesively bonded both to said stem wires and to said brush material effective to retain said stem wires in close direct opposition to one another for continued tight gripping of said brush material and also effective to prevent shifting of said brush material, said elastomeric material penetrating said brush material to effect a direct connection between said respective stem wires.
2. The brush of claim 1, wherein said stem wires have opposed fiat faces.
3. The brush of claim 1, wherein said brush material is steel wire.
4. The brush of claim 1, wherein said brush material comprises a single row of parallel wire bristles.
5. The brush of claim 1, wherein said elastomeric material is polyurethane.
6. The brush of claim 1, wherein said elastomeric material is foamed polyurethane.
7. The brush of claim 1, wherein said elastomeric material extends only a portion of the length of said brush material outwardly from said stem wires and is of gradually diminishing thickness to afford progressively less support for such brush material toward the outer working ends of the latter.
8. A twisted wire stem brush comprising two stem wires twisted together with brush material clamped therebetween, and elastomeric material bonded both to said stem wires and to said brush material and penetrating the latter effective directly to retain said stem wires in close direct opposition to one another for continued tight gripping of said brush material and also efiective to prevent shifting of said brush material, said elastomeric material extending only a portion of the length of said brush material outwardly from said stem wires and being of gradually diminishing thickness to afiord progressively less support for said brush material toward the outer working ends of the latter, said elastomeric material having a general meniscus surface contour between said stem wires and the exposed outer portions of said brush material.
9. The brush of claim 8, wherein said elastomeric material is polyurethane.
10. The brush of claim 8, wherein said elastomeric material is a foamed elastomer.
11. The brush of claim 8, wherein said brush material is straight Wire bristles.
12. In a brush comprising two stem members and a fiat layer of brush material held therebetween, strong adhesive bonding material embedding said brush material in the region of said stern members and also adhesively bonding said two stem members directly together to prevent separation of the latter.
13. The brush of claim 12, wherein said bonding material is an elastomeric material.
14. The brush of claim 12, wherein said bonding material is polyurethane.
15. The brush of claim 12, wherein said bonding material is foamed polyurethane.
16. In a brush comprising two stem members and a flat layer of brush material held therebetween, elasto meric material adhesively bonded directly to both said stem members and to said brush material eifective to re tain said stem members in close direct opposition to one another for continued tight engagement with said brush material and also effective to prevent shifting of said brush material.
17. The brush of claim 16, wherein said elastomeric material extends only a portion of the length of said brush material outwardly from said stem members and is of gradually diminishing thickness to afford progressively less support for said brush material toward the outer working ends of the latter.
18. In a twisted wire stem brush having two stem wires twisted together and a helical generally flat layer of brush material clamped therebetween, elastomeric material interposed between the helical turns of brush material and embedding the inner portions of the latter adjacent said stem wires, said elastomeric material being adhesively bonded to said stem'wires and all said brush material and being of gradually diminishing thickness outwardly toward the working ends of said brush material to afford progressively diminishing support for said brush material toward such outer ends.
19. The brush of claim 18, wherein said elastomeric material completely fills the space between such helical turns of brush material in the region adjacent said stem wires.
20. The method of producing a brushing tool which comprises securing spaced layers of brush bristle material to a central support with such bristles extending generally radially outwardly from the latter, applying a rapid gelling liquid elastomeric resin to such assembled brush in contact with such support, and then rotating such brush about the longitudinal axis of such support uniformly circumferentially to distribute such resin while the resin gels to meniscus conformation on each side of each such layer of bristle material.
21. A brushing tool comprising a central support and spaced layers of brush material secured thereto and extending generally radially outwardly therefrom, and elastomeric material bonded to said bristles and also to said support intermediate said layers, said elastomeric material being formed in general meniscus shape so that it extends outwardly along such layers in gradually diminishing thickness while still bonded thereto.
References Cited in the file of this patent UNITED STATES PATENTS 2,190,206 Churchill Feb. 13, 1940 2,634,167 Bible Apr. 7, 1953 2,895,155 Peterson July 21, 1959 2,950,495 Stingly Aug. 30, 1960 2,995,401 Peterson Aug. 8, 1961 FOREIGN PATENTS 409,462 Great Britain May 3, 1934 827,928 Great Britain Feb. 10, 1960