Power brush

Details Power brush Power brush

2001-09-17

2002-12-10

Till, Terrence R. (Department: 1744)

Brushing, scrubbing, and general cleaning

Implements

Brush or broom

C015S230000, C015S230170

Reexamination Certificate

active

06490750

ABSTRACT:

TECHNICAL FIELD
The present invention relates generally to improved brushes used for surface conditioning. More specifically, the present invention relates to a power brush having an improved tube assembly system. The present invention also relates to an improved power brush adapter that permits the power brush to accommodate a variety of mounting shaft sizes and also permits the shaft to provide positive transmission of torque to the power brush.
BACKGROUND OF THE INVENTION
High speed rotary brushing is well known as a means for surface conditioning, particularly for metallic objects, and is suitable in a diverse array of applications in areas such as the automotive, farm, and hardware industries. Brushing is an effective technique for cleaning a surface, altering a surface finish, and limited material removal. Brushing permits surface roughening as well as surface smoothing as for deburring or radiusing. The use of a rotary power brush on an object results in a surface with generally uniform scratches, and this surface finish is often acceptable for a given application. Objects that require a scratch-free surface may be subjected to a variety of secondary polishing operations in order to achieve the desired surface finish, such as buffing the object with a cloth wheel charged with a polishing rouge. Brushing is typically accomplished by manually bringing a workpiece in contact with the rotating power brush, or conversely by bringing the power brush in contact with the workpiece. In more sophisticated operations, the brushing task may be automated.
Brush construction features can directly impact the expected brush service life and performance level. Generally, the more rigid and structurally solid a power brush is constructed, the finer the surface finish and the longer the service life of the power brush. A dynamically-balanced power brush assembly transmits less vibration to the equipment and the workpiece, thereby providing enhanced performance.
An important design consideration for a rotary power brush is the choice of central hub construction. Because power brushes generate heat during operation, effective means for heat dissipation must be provided. Metal hub assemblies, which have large contact areas with the mounting shaft, permit thermal conduction from the power brush through the hub and mounting shaft, facilitating heat dissipation.
Filament density, or the number of working filament tips per unit area (commonly referred to as points per square inch), impacts performance as well. Increasing brush filament density results in a finer, more uniform surface finish. A denser-filled brush is more aggressive to the work-piece due to reduced filament flexibility as well as increased working points in contact with the surface per brush revolution. Increased brush filament density also provides longer brush life. Brush filament density can be increased by adding more fill material to an existing design or by reducing the ratio of brush section outside diameter to brush section inside diameter. Brushes having smaller individual filament diameters tend to follow the contours of the workpiece more closely and to produce a more uniform surface, whereas as the density of filaments increases, the brush loses some of its ability to follow contours. Finer diameter filaments are less aggressive toward the workpiece and may result in longer cycle times.
The modern approach to designing and manufacturing power brushes typically involves combining individual, narrow sections together to form a wider face width, thereby producing a generally consistent brush filament density over a large area. Typically, power brushes are formed by mounting a plurality of brush sections on an arbor tube and then mounting a face plate at each end of the arbor tube to maintain the brush sections therebetween. Each brush section is formed by wrapping the brush filaments (e.g., wires) about a retaining ring (which may resemble a washer). The filaments are typically held in place about the retaining ring by friction, such as through the use of an eyelet, so that welding or use of adhesives is not necessary. Once the face plates are positioned at each end of the arbor tube, surrounding the brush sections, the ends of the arbor tube are flanged over the face plates, such as through the use of a hydraulic press which cold-works the material, to secure the face plates in place on the arbor tube. But, internal friction between the component parts and minor variations in section thickness result in a finished power brush assembly with an overall thickness that varies with each power brush produced. In particular, the brush sections are not necessarily brought together in a uniform manner from finished brush to finished brush. Thus, although the number of filaments on each retaining ring typically is set, and the number of brush sections mounted on the arbor tube is set, the stacking of the brush sections against one another and the distance between the face plates is not readily controllable. Accordingly, the packing of the brush sections, and hence the density of the brush filaments of the finished power brush may vary from brush to brush. Thickness variations on the order of 75 to 100 thousandths of an inch may occur potentially resulting in uneven cleaning action may be imparted to a workpiece due to the variation in brush packing.
While the above-described rotary power brush developments permit a rotary power brush to be produced with a reliable construction, it is desirable to manufacture an improved rotary power brush with a structure that provides a more consistent brush filament density.
Certain operating factors also can significantly impact brushing quality and service life. In particular, a more secure connection of the power brush to the drive shaft results in a better surface finish, longer brush service life, and reduced vibration and chatter which cause surface imperfections. Furthermore, by minimizing relative motion between the internal components of the power brush, decreased component wear and degradation are realized.
In rotating machinery, torque may be transmitted from shafts to coupling hubs (or vice versa) through keys, friction, or a combination thereof. A solid connection must be maintained between the driving and the driven components in such a mechanical power transmission system in order to achieve satisfactory performance. Because keyed designs typically are not used in power brush equipment, a relatively tight fit is desirable to achieve frictional engagement to drive the power brush. A true interference fit would contribute to the transmission of torque and also would help to prevent the hub from rocking on the shaft. However, a tight interference fit is not desirable because of the difficulty users experience with changing or removing power brushes from shafts. Thus, coupling hubs, such as arbor tubes, instead are generally installed on shafts with a small amount of clearance to facilitate installation and removal. To secure the power brush on the drive shaft more securely and to prevent relative rotation, a drive flange is clamped on either side of the power brush to engage the face plates of the power brush frictionally so that the power brush may be driven by friction. Such clamping further maintains a secure connection between the power brush and the associated shaft, particularly because keyed systems have not been used between the shaft and arbor tube.
An example of suitable means for holding and centering grinding and polishing wheels or the like on a drive shaft is disclosed in U.S. Pat. No. 1,584,835 to Sven Blanch. The grinding wheels include a central ring that has a passage therethrough which is larger than any arbor on which it is likely to be placed. To center the wheels on arbor tubes of different diameters, a set of two sheet metal discs of the same size is provided, with one disc fitting on each side of the passage through the central ring. Each disc is provided with an annular projection having a cylindrical shoulder that fits the inner wall of the passage through

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