US3900914A

US3900914A - Rotary brush core assembly

Info

Publication number: US3900914A
Application number: US440369A
Authority: US
Inventors: Susan H Lewand
Original assignee: Danline Manufacturing Co
Current assignee: Danline Manufacturing Co
Priority date: 1974-02-07
Filing date: 1974-02-07
Publication date: 1975-08-26
Anticipated expiration: 1992-08-26

Abstract

A brush core for supporting and rotatably driving a brush or series of parallel brush rings carrying radially extending brush filaments includes a plurality of flat surfaces forming a polygon tangentially circumscribing a central supporting shaft coplanarly extended outwardly to the inner surface of the brush, the flat surfaces rotatably driven by means engaging an end flange.

Description

United States Patent [191 Lewand Aug. 26, 1975 1 ROTARY BRUSH CORE ASSEMBLY [75] Inventor: Susan H. Lewand, Colonia, NJ.

[73] Assignee: Danline Manufacturing Company, Kenilworth, NJ.

22 Filed: Feb. 7, 1974 21 Appl. N01: 440,369

[52] US. Cl 15/181; 300/21 [51] Int. Cl A46b 7/10 [58] Field of Search 15/179, 181, 182, 183,

[56] References Cited UNITED STATES PATENTS 3,321,799 5/1967 Hackworth 15/182 3,471,889 10/1969 Mikke1sen..... 29/129 X 3,481,017 12/1969 Hunt 29/123 3,839,763 10/l974 Gould 15/181 FOREIGN v PATENTS OR APPLICATIONS 1,032,286 6/1966 United Kingdom 15/181 Primary Examiner-Peter Feldman Attorney, Agent, or FirmLitt1epage, Quaintance, Murphy & Dobyns [5 7 ABSTRACT A brush core for supporting and rotatably driving a brush or series of parallel brush rings carrying radially extending brush filaments includes a plurality of flat surfaces forming a polygon tangentially circumscribing a central supporting shaft coplanarly extended outwardly to the inner surface of the brush, the flat surfaces rotatably driven by means engaging an end flange.

6 Claims, 9 Drawing Figures PATENTEB AUG 2 6 I975 ROTARY BRUSH CORE ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the Invention NL N (A (tan 1r/N tan (arccos A/B) -T (cot 2rr/N cot (arccos A/B) and E (A T) sec rr/N T 1% sec ar/N -l). Generally, the considerations of strength of materials This invention relates to rotary heads and casings of requires that B 5 5A.

brushes and brooms and more particularly to assemblies for supporting and driving a brush or series of brushes carrying radially extending bristles.

2. Prior Art Circular tubes have been suggested as cores for radially extending brushes, but have been generally considered as too heavy. An example of such an apparatus is found in US. Pat. Nos. 2,757,401 and 3,481,017.

A plurality of angle members fixed parallel to a rotation axis by radially extending cross-member plates has also been suggested as a brush core. Such a structure is not only expensive to produce and assemble, but is susceptible to misalignment during use. An example of such an apparatus if found in US. Pat. No. 3,321,799.

Another previously known structure consists of a plurality of inwardly opening U-shaped plates joined together by flat plates fixed to the tops of the Us, the tube formed thereby supported by end plates extending from a central axis into the U openings. While some advantages are to be realized, the core is subject to unwanted flexing and bending during operation, possibly resulting in permanent misalignment. An example of this structure is to be found in US. Pat. No. 3,471,889.

Flat plates have also been joined in more simple polygonal tube shapes with projecting plate flanges, the tubes supported again by end plates fixed to the polygon and to the central axis. Again, unwanted flexing and bending possibly resulting in permanent misalignment or metal fatigue contributing to structural failure can result. An example of this structure is to be found in British Pat. No. 1,032,286.

SUMMARY OF THE INVENTION A brush core which resists flexing and bending without resorting to costly cross-member construction consists of a plurality of flat surfaces joined to form a regular polygon tangentially circumscribing a central supporting shaft. Each surface is geometrically produced or coplanarly extended at an apex of the polygon to the inside surface of the brushes supported and rotatably driven by the brush core. End flanges fixed to the surfaces are rotatably driven by engaging means, typically pins, rotated by a motor means.

The preferred polygon is determined by minimizing the materials necessary to form the polygonal shape, thus reducing the weight as much as possible, while retaining the basic structural features which prevent unwanted displacement of the core. The parameters to be considered are the radius of the central shaft, the inside radius of the brushes, and the strength of the material under consideration.

In general if N is the number of sides of the regular polygon to be chosen, each side made of a plate having a thickness T much thinner than the radius A of the central shaft, and B is the inside radius of the brush rings then the number of sides of the core is determined approximately by the following relations NL NA (tan vr/N tan (arccos A/B) and E A sec (Tr/N).

considering the variation due to the thickness of the flat plates, the relations become If the radii A and B are free to be chosen, the strongest structure is presented by a core of triangular crosssection and A and B should be appropriately chosen to satisfy the parameters when N 3.

Each of these relations will become apparent from the following discussion of the Figures.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a rotary brush core assembly with the removable end flange removed.

FIG. 2 is an end view of the brush core of FIG. 1.

FIG. 3 is a perspective view of a brush ring usable with a brush core according to this invention.

FIG. 4 is a geometric simplification of a square brush core.

FIG. 5 is a geometric simplification of a triangular brush core.

FIG. 6 is a diagrammatic representation of a portion of an N-sided brush core.

FIG. 7 is a detail of a portion of FIG. 6 modified to some extent.

FIG. 8 is a detail of another portion of FIG. 6.

FIG. 9 is an end view of an extruded brush core according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows in perspective a rotary brush core assembly 10 according to this invention which is composed of a plurality of flat rectangular metallic sheets 12. The sheets are skip-welded or otherwise fixedly joined at the plate junctions 14. The junctions can be viewed as the apices of a regular polygon, the sides of which are formed by the plates 12. Each plate 12 extends coplanarly from the apex 14 to the inside of the brush rings. The plates are each tangent to a central shaft 16 which supports the core and is easily slidably removable therefrom. The shaft may be either solid or tubular, depending on the strength of materials selected for use as well as other parameters.

Welded or otherwise secured to one end of the polyg onal core 10 is a fixed end flange 18 having a plurality of holes or other means 20 for engaging a motor-driven element (not shown) adapted'to rotate the brush core. At the opposite end from the fixed end flange 18 is a removable end flange 22 removably secured to the core by bolts or screws 24. The removable end flange 22 can also have slots or holes 26 adapting the end flange to a number of drive means not shown.

An end view of the brush core assembly of FIG. 1 is shown in FIG. 2 with the removable end flange 22 removed. The flat metal plates 12 are each slidably tangent to the central shaft 16, the shaft being in general a part of a larger apparatus utilizing the brush core and not an integral part of the brush core as such. Nuts 28 can be secured to the flat plates 12 to receive the bolts or screws 24 securing the removable flange 22 to the rest of the core assembly. The dotted line 30 indicates the position of the inside surface of the brush ring shown in FIG. 3. i

The brush ring 32 is of standard conventional design having a metallic hub 34 crimped or otherwise securing the brush fiber material 36. Adrive pin 38 fixed to'the hub 34 is used to rotate the whole brush ring by contacting the extended portionsof the brush core flat plates 12.- j i I The use of flat plates which are readily. available and require no special forming or bending operations simplify and speed the fabrication of the brush:core. The resulting core is easierto use in that the tangencyof the plates 12 to the central shaft 16 ensures centeringof the core on the shaft and eliminates the needfor manual alignment of the core and end plates. The whole brush core with brush rings in place thereon can be slidably removed from the central supporting shaft or alternatively the core can be left in place and the brush rings changed by removing the end flange 22 and sliding the brush rings off the core. As well as minimizing the weight of the core by selectingthe optimum number; of flat plates consistent with the relations herein developed, the weight is additionally'reduced by eliminating the need for separate H brush-retaining end flanges and core supporting end 38 of the brush ring to be contacted at the base of the pin next to theirlside surface of the brush ring, thereby minimizing the bending load applied to the pin. A brush core according to this invention can also be formed of a plastic resin or metal by conventional continuousextrusion methods. Such a core 210 shown in FIG. 9 has a plurality of flat surfaces 212 which form unitarily a regular polygon and coplanarly extend from fthe'apices 214 of the polygon to the inside of a brush 230 rotatably carried by the core. A drive pin or bar 238 fixed to the brush 230 is contacted at its base by one of the flat surfaces 212 to rotatably drive the brush 230. The extruded core 210 is supported by a central shaft 216 which may be solid or hollow. The flat surfaces 212 are tangent to theshaft 216, but easily slidably. removable therefrom. Where tangenfand tangentially a're iu sed in this specification and iri the claims, it is to include v not only strong frictional e'ngagement between a curvedsurface and a flat plane, but

also the substantial physical equivalent considering the dimensional tolerances which are necessary to permit easy removal and replacement of the elements concerned. Brush is used herein generically to include a single element or a plurality of elements whether in cylindrieal, ring, spiral strip, or other form.

' 'The triangular cores shown in FIGS. 1, 2 and 9 have the preferred configuration as it represents the strongest of thepossible polygon-cross sections. If either the inside radius of the brush or the outside radius of the central shaft are not subject to other conflicting constraints, they should be chosen such that the other parameters herein developed can be used with N 3.

" In FIGS. 4 and 5, a square 110 and a triangle 112 respectively are circumscribed about a. circle. of radiu'sA. The square 110 and the triangle 112 are each tangenttothe inscribed circle 114'at points 116. Each side of the regular polygons 1il0-and 112 are geometrically produced at an apex of the polygon to a concentric circle 118 of radius B, each line segment so pro..

duced indicated by the numeral 12 If C is a radius vector to an apex 117 of the polygon and A is a radius vector to an adjacent point on the polygon tangent to the inscribed circle 114 then the angle between the two vectors is 'rr/3 in the case of the triangle, 'rr/4 in the case of the square or, in general, 'Ir/N in the case of a regular polygon having N sides.

Toinsure that the polygon is in fact a closed figure, the radius B of the circle 118 must be greater than the length of the' vector C.

The length of half of a side-of the polygon (the length of the line segment between the tips of the vectors A and C) is equal to A tan rr/N. The length of a side of a polygon is then 2A tan 'lT/N.

If B is a radius vector to a point of intersection on circle 118 with a produced side 120 of the concentric polygon, and A is a radius vector to the point of tangency on the same side of the polygon, then the angle 6 between the two vectors is equal to arccos A/B and the length of the line segment opposite that angle is equal to A tan (arccos A/ B).

The total length L; of a side of a polygon and the line segment produced therefrom to circle 1 18 is then given by L A tan rr/N A tan (arccos A/B). The total length of all such line segments forming the N sides of the polygon and the single segments 120 produced therefrom is NL NA (tan 7T/N tan (arccos A/B) A rotary brush core assembly as shown in FIGS. 1-3 can be constructed based upon the geometric relations herein developed where the circle 114 represents the central supporting shaft 16 and circle 118 represents the inner surface 30 of rings, cylinders, or helical closewound strips carrying radially extending bristles. The sides of the regular polygon and the single segments extending therefrom represent a plurality of. flat surfaces 12 circumscribing the supporting shaft 16. Since the weight of the flat surfaces 12 is largely dependent upon their dimensions and it is desirable to build as light weight a core as possible consistent with strength requirements, the quantity NL should be minimized for any particular sizes of A and B by selecting a polygon of the proper number of sides N. For example, if B 3A then for a triangular core NL 13.7A

while for a square core NL 15.3A, and since the triangular core has the smaller linear dimension, it would be selected.

If B is too small as compared to A, then a triangular core cannot be used as the triangle will not be completed inside the circle 118 and still remain outside t e circle 114. The radius B must be greater than C to retain the general configuration intended. C in general is equal to A sec Tr/N. If for example B 1.8A, for a triangular core NL 9.69A, for a square core NL 10.0A, for a pentagonal core NL z 11.15A, and for a hexagonal core NL z 12.48A. While the triangular core would appear to be the best selection, B A see 'rr/N or in this example see w/N 1.8 and if N 3, sec *rr/N 2.00; if N 4, sec 'rr/N 1.42; if N 5, sec 1r/N 1.24; and if N 6, sec 1r/N 1.16. The core must then have 4 or more sides to satisfy all the requirements present in this example.

7 lateral triangle which is congruent with any triangle formed by joining an apex with the two closest points of tangency. The four triangles thus formed represent a superior configuration from the standpoint of strength. In all such configurations, the central figure formed by joining the points of tangency is reflective of the polygon circumscribing the circle 114.

FIG. 6 shows a portion of a brush core having N sides circumscribed about circle 114 and produced out to a concentric circle 118 representing similar portions of structure as in previous figures. The lines of the polygon and segments produced therefrom in FIGS. 4 and 5 have been replaced with elements 112 having a thickness T. Vectors A, B, and C are similarly situated as in FIGS. 4 and 5. Vector B is a radius vector to the point of intersection between element 122 and circle 118. The angle between vectors A and C is 1r/N, while the angle 0 between vectors A and B is arccos A/B.

The thickness of element 122 changes the relations previously determined. FIG. 7 is an enlargement of the section of FIG. 6 showing the intersection of the two shown elements 122 modified by the requirement that the elements just meet. This condition specifies the minimum radius B for the outer circle 1 l8 and the minimum is shown as the dotted extension of the vector C to the circle 118. That is, B C A" to retain the general structure intended.

As shown in the detail of FIG. 7, the length A'is the hypotenuse of a right triangle having one leg 124 of length T, the thickness of the element 122. The leg 124 is parallel to vector A which, similarly to vector A, is at an angle 7T/N from vector C. The angle between leg 124 and length A is then also vr/N and A =T sec IT/N.

The length A is a leg in yet another right triangle with the angle opposite that leg equal to 1r/N The hypotenuse 126 of the triangle has a length equal to the length of the hypotenuse 128 of the triangle having 6 for a leg-minus leg 130 of the triangle having A as a hypotenuse. The leg 130 has length T csc 'rr/N, while hypotenuse 128 has length T csc 21r/N. I-Iypotenuse 126 must therefore have a length of T( csc 21r/N csc 1r/N) and A T (csc 21r/N csc rr/N) sin vr/N. This may be simplified to A T /2 sec 'rr/N 1) and thus B (A T) sec 'rr/N T( /zsec1r/N 1).

FIG. 8 is an enlargement of that portion of FIG. 6 showing the element 122 contacting the circle 118. At the circle 118 contacting end, each element 122 is shortened by a length 6 from the line segments 120 of FIGS. 4 and 5. Since the angle between the line segment e, and the circle 118 is equal to angle 6 of FIG. 6, e, z Tcot (arccos A/B). The element 122 is shortened on the other end by a length 6 shown in FIG. 7 given by 6 T cot 21r/ N. Thus the length L of each element is L A(tan 'n/N tan (arccos A/B)) T(cot 21r/N cot (arccos A/B)).

What is claimed is:

1. In a rotatably driven brush assembly comprising a central supporting shaft, a brush core slidably mounted on the supporting shaft, and a brush circumferentially encompassing the core and carrying radially extending brush filaments, an improved brush core comprising a plurality of flat plates forming a regular polygon tangentially circumscribing said supporting shaft, each plate coplanarly extended at an apex of the polygon to the inside surface of said brush.

2. The brush core of claim 1 further comprising end flanges fixed to said plurality of flat surfaces having a diameter greater than the inside diameter of the brush for retaining the brush on the core.

3. The brush core of claim 2 wherein at least one of said flanges is removably fixed to the plurality of flat surfaces for allowing replacement of the brush.

4. The brush core of claim 3 wherein at least one of said flanges further comprises means for receiving motive power and thereby rotatably driving said brush.

5. In a rotatably driven brush assembly comprising a central supporting shaft, a brush core slidably mounted on the supporting shaft, a brush core slidably mounted on the supporting shaft, and a brush circumferentially encompassing the core and carrying radially extending brush filaments, an improved brush core comprising three flat plates forming a regular triangle tangentially circumscribing said supporting shaft, each plate coplanarly extended at an apex of the triangle to the inside surface of said brush, and two flanges, one fixed to each opposite end of the three plates for retaining the brush on the core, at least one of said flanges having engaging means for receiving motive power, and at least one of said flanges being removably fixed to the joined flat plates for allowing replacement of the brush.

6. In a rotatably driven brush assembly comprising a central supporting shaft of radius A, a brush core slidably mounted on the supporting shaft, and a brush having an inside radius of B circumferentially encompassing the core and carrying radially extending brush filaments, an improved brush core comprising a plurality of flat plates of thickness T and of equal length L forming a regular polygon having N sides tangentially circumscribing said supporting shaft, each plate coplanarly extended at an apex of the polygon to the inside surface of said brush and the values of B, N, T, L and A determined by the relations B (A T)sec 'rr/B T /2 sec rr/N 1) and NL N (A (tan qr/N tan (arccos A/B)) T (cot 2'rr/N cot (arccos A/B))).

Claims

6. In a rotatably driven brush assembly comprising a central supporting shaft of radius A, a brush core slidably mounted on the supporting shaft, and a brush having an inside radius of B circumferentially encompassing the core aNd carrying radially extending brush filaments, an improved brush core comprising a plurality of flat plates of thickness T and of equal length L forming a regular polygon having N sides tangentially circumscribing said supporting shaft, each plate coplanarly extended at an apex of the polygon to the inside surface of said brush and the values of B, N, T, L and A determined by the relations BN > (A + T)sec pi /B + T ( 1/2 sec pi /N - 1) and NL N (A (tan pi /N + tan (arccos A/B)) - T (cot 2 pi /N + cot (arccos A/B))).